fix(demo): mingwX64 compile — currentResidentMb via expect/actual

platform.posix.popen/pclose don't exist on mingw (Windows uses _popen/_pclose),
so the soak-test RSS helper failed :demo:compileKotlinMingwX64 (broke the v0.2.0
publish). Make currentResidentMb() an expect: posix (appleMain/linuxMain) reads
`ps -o rss=`, mingw returns -1 (the soak gate runs on macOS/Linux). Verified
:demo:compileKotlinMacosArm64 green.

.gitignore

@@ -61,3 +61,6 @@ bin/
 ### Python ###
 __pycache__/
 *.pyc
+
+# Probe artifacts written to the repo root by demo --nav3test / --searchesctest / --dialoganimtest
+/*.bmp

CLAUDE.md

@@ -3,6 +3,21 @@
 Guidance for Claude Code working in this repository. This is the primary
 context — read it first, then look at the files it points to.
 
+## Documentation map
+
+- [README.md](README.md) — public overview + quickstart (bridge plugin,
+  `nativeComposeWindow`, sample apps).
+- [RENDERER.md](RENDERER.md) — the rendering layer: architecture, the retained-
+  layer engine, convergence decisions, learnings, and open work. Read it before
+  touching any renderer, graphics-actual, or layer-engine code.
+- [TOOLING.md](TOOLING.md) — build/vendor/verify scripts and workflows
+  (build-sdl, sync + drift checks, parity, probe, profiler, coverage,
+  verify-mac) + the version map and the ref-bump / release runbooks.
+- [TODO.md](TODO.md) — audited list of no-ops, stubs, and hardcodes left in the
+  port, with severity, plus what's missing for a stable 1.12 release.
+- This file — architecture, module layout, vendoring rules, source-set
+  hierarchy, density flow, conventions, and common pitfalls.
+
 ## What this project is
 
 **ComposeNativeSDL3** — a Kotlin/Native port of Compose Multiplatform running
@@ -228,10 +243,23 @@ Two categories of code live in each module:
    NON-IDEMPOTENT.** Move it OUT of `src/vendor/` into the corresponding
    `src/{commonMain,nativeMain,…}` tree, add a header comment noting
    which upstream file it derived from and what changed, and comment
-   its line out of `compose-fork.txt`. Now it's a project file — the
-   next sync won't overwrite it, and future upstream changes to that
-   file need to be reconciled by hand. This is fine; do it when the
-   edit is small and the file is unlikely to churn upstream.
+   its line out of `compose-fork.txt`. **ALWAYS also add the
+   machine-readable provenance line** so the copy can be diffed against
+   its base and against later upstream versions:
+
+   ```
+   // VENDOR-BASE: <upstream-repo-relative-path> @ <pinned-tag>
+   // VENDOR-BASE(COMPOSE_REF): <path> @ <tag>     ← for umbrella-repo files
+   ```
+
+   `scripts/compose-fork/check-vendor-drift.py` reads these at every ref
+   bump: it flags any file whose recorded base lags the current pin and
+   (with the local clone) reports whether the upstream base ACTUALLY
+   changed base..pin — i.e. whether the copy needs hand-reconciling or
+   just a ref re-stamp. Now it's a project file — the next sync won't
+   overwrite it, and future upstream changes to that file need to be
+   reconciled by hand. This is fine; do it when the edit is small and
+   the file is unlikely to churn upstream.
 
 4. **Skiko-specific things go in `:ui/src/skikoRendererMain/`, with
    an SDL3 equivalent in `:ui/src/sdlRendererMain/`.** When upstream
@@ -354,19 +382,10 @@ gradlew.bat :apidemo:runDebugExecutableMingwX64
 
 SDL3 + SDL3_ttf + SDL3_image + FreeType (+ image codecs) are **built from
 source as static libraries on every OS** and linked straight into the
-executable — no brew/apt SDL packages, no runtime .dll/.so/.dylib;
-a distributable is `<app>` + `data.kres`. One script does it all:
-`python scripts/build-sdl/build-all.py` (plain Python 3, no Git Bash needed)
-builds into the gitignored, in-repo `libs/` folder. Versions/URLs pinned in
-`scripts/build-sdl/build-sdl.properties`. Steps run in order freetype → sdl3
-→ sdl3-image → sdl3-ttf; pass step names to rebuild a subset
-(`python scripts/build-sdl/build-all.py sdl3-ttf`).
-
-Needs everywhere: git, cmake, python 3 (ninja fetched automatically). Per
-host: macOS = Xcode CLT (Skia default; Skiko klibs from Maven); Linux =
-gcc/g++ + the X11/Wayland/audio dev headers SDL3's configure detects (apt
-list in .github/workflows/publish.yml); Windows = mingw-w64 g++ on PATH
-(C compiles with K/N's bundled mingw).
+executable — no brew/apt SDL packages, no runtime .dll/.so/.dylib; a
+distributable is `<app>` + `data.kres`. Build them once per host with
+`python scripts/build-sdl/build-all.py`. Per-host toolchain requirements and
+the step breakdown are in [TOOLING.md](TOOLING.md#native-libraries).
 
 ## Runtime bundling — data.kres
 
@@ -392,19 +411,13 @@ executable, loaded via `SDL_GetBasePath()`). Contents:
 ```bash
 # Sync every module's compose-fork.txt against the pinned upstream ref.
 scripts/compose-fork/sync.sh
-
-# Sync one module by direct manifest path (module names use ':' → '/' → skip
-# 'compose/' prefix — nested modules like compose/sdl/window pass the full path).
-scripts/compose-fork/sync.sh compose/ui/compose-fork.txt
-
-# Re-format a manifest (align columns, group by upstream folder).
-scripts/compose-fork/format-manifest.py --discover ../cmp-ref \
-    --manifest compose/ui/compose-fork.txt
 ```
 
-Upstream ref: `scripts/compose-fork/compose.properties` — set to a specific commit
+Upstream ref: `scripts/compose-fork/compose.properties` — set to a durable tag
 of `JetBrains/compose-multiplatform-core`. Bump the ref → re-sync → let the
-build tell you what broke.
+build tell you what broke. Per-module sync, manifest re-formatting, and the
+drift / vendor-clean guardrails are in
+[TOOLING.md](TOOLING.md#vendoring-upstream-compose).
 
 ## Key files by area — start here when you need to find something
 
@@ -458,95 +471,20 @@ build tell you what broke.
   `Dialog` / `DropdownMenu` / `DropdownMenuItem` / `TooltipBox` (m3 doesn't
   ship drop-in equivalents for our anchor / scrim patterns).
 
-## Tooling — what's available and when to reach for it
+## Tooling
 
-Index of the repo's tooling. Each entry says when to use it and points at its
-own README for detail; the parity/profiler/probe entries are expanded below
-since they're newer.
+The full tooling reference is [TOOLING.md](TOOLING.md): the static-lib build,
+vendor sync + drift/clean guardrails, API coverage, the `verify-mac` runbook,
+the native-vs-JVM parity harness, the interaction probe, and the frame
+profiler. Quick rules of thumb:
 
-| Tool | Reach for it when | Detail |
-|------|-------------------|--------|
-| `python scripts/build-sdl/build-all.py` | building/refreshing the static SDL3/TTF/image/FreeType libs under `libs/` (once per host, or after bumping `build-sdl.properties`) | "Building" above |
-| `scripts/compose-fork/sync.sh` | re-syncing vendored upstream `androidx.compose.*` after a fresh checkout or a `compose.properties` ref bump; `format-manifest.py` to re-align a `compose-fork.txt` | "Vendor sync workflow" above + `scripts/compose-fork/README.md` |
-| `./gradlew apiDump && python scripts/compose-coverage.py` | measuring how much upstream public API the port actually covers, per module (`--missing <module>` lists uncovered decls) | "Vendoring" above |
-| `scripts/generate-material-symbols.py` / `subset-material-symbols.py` | regenerating the Material Symbols codepoints, or hb-subsetting bundled icon fonts to used glyphs (the latter runs automatically in app Zip tasks under `-PsubsetIcons`) | — |
-| **`scripts/parity/parity.py`** | after ANY renderer/layout change: catch a screen that visually diverged native-vs-JVM (missing content, wrong shape/colour, broken clip) | `scripts/parity/README.md` + below |
-| **`scripts/probe/probe.py`** | reproducing a specific interaction bug (click/hover/hold at a point) or grabbing one screen's pixels deterministically | `scripts/probe/README.md` + below |
-| **`CDN_PROFILE=1 <app>`** | finding where a slow frame goes (per-phase main-loop timings) before optimizing | below |
-| bridge plugin (`com.bitsycore.compose-desktop-native.bridge`) | consuming the published klibs from a third-party app | `gradle-plugin/compose-desktop-native-bridge/README.md` |
-| `demo --screen=<Name>` / `--screenshot=` / `--nav3test` / `--backtest` / `--multiwintest` | driving one screen headless, or the regression probes for nav3 / predictive-back / multi-window | `demo/src/nativeMain/kotlin/MainNative.kt` |
+- Whole-project renderer/layout change → run **parity** (`scripts/parity/parity.py`),
+  the broad net.
+- Chasing one reported interaction → run the **probe** (`scripts/probe/`), targeted.
+- Slow frame → **profiler** first (`CDN_PROFILE=1`), optimize second.
+- Any renderer change → the **`verify-mac`** runbook gates both legs before commit.
 
-Whole-project renderer-touching change → run **parity** (broad net). Chasing
-one reported interaction → **probe** (targeted). Slow → **profiler** first,
-optimize second. See `ROADMAP.md` for the renderer work these support.
-
-### Frame profiler — `CDN_PROFILE=1`
-
-Set the env var (`CDN_PROFILE=1`, or `=<path>` for a specific file) and run any
-native app; every ~2 s of rendered frames it writes avg/max ms per main-loop
-phase (`events` / `app` pump / `pump` per-window / `render`) to a FILE
-(`cdn_profile.log` by default — works for GUI-subsystem apps like the demo that
-have no console). The line also carries render SUB-phases (`layout` / `draw` /
-`present`) and per-frame DRAW COUNTERS from `DrawStats` (`geo` =
-SDL_RenderGeometry submits, `verts`, `masks` = rounded-clip offscreen passes,
-`text`, `img` blits) — so you can see WHAT `draw` is doing, not just that it's
-slow. `CDN_FORCERENDER=1` renders every frame (bypasses idle-skip) so
-steady-state timings can be read on otherwise-idle static screens.
-
-**Caveat learned the hard way:** `present` is vsync-blocking, so every timing is
-capped by the DISPLAY refresh of the machine running the app. A 75 Hz dev
-display makes every app look "75 fps, present-bound" no matter what — so profile
-on the TARGET refresh rate before concluding anything about a frame-rate gap
-(the demo-70 / apidemo-144 report could not be reproduced on a 75 Hz box, where
-both pinned at 75 fps and the demo's `draw` was actually the lighter of the two).
-
-### Interaction probe — `scripts/probe/`
-
-Launches a native app, sends **window-client-relative** input (click / hover /
-hold, fractional coords addressed by process name so it ignores window
-position/focus) and captures the client area via `PrintWindow` (works even
-when occluded). The packaged form of the rigs that reproduced the
-square-on-click and TLS-chain bugs. Windows-only. See its README.
-
-### Parity harness — native-vs-JVM screenshot diff (`scripts/parity/`)
-
-`:demo` renders the **same commonMain screens** on two stacks: native
-(SDL/Skia, Kotlin/Native) and a `jvm()` target on upstream Compose Desktop.
-`scripts/parity/parity.py` screenshots every screen on both and pixel-diffs
-them, so a screen that visually diverges is a **port regression** (missing
-content, wrong shape/colour, broken clip). Several past renderer regressions
-would have been caught here.
-
-```bash
-python scripts/parity/parity.py                 # all screens (builds first)
-python scripts/parity/parity.py Buttons Shapes  # a subset
-python scripts/parity/parity.py --no-build      # reuse the last renders
-```
-
-Mechanics: the JVM leg renders all screens headlessly via `ImageComposeScene`
-in ONE process (`:demo:run --args=--screenshot-all=<dir>`, wired in
-`MainJvm.kt`); the native leg launches the exe once per screen
-(`--screen=<Name> --screenshot=<x>.bmp`). Output lands in **`build/parity/`
-(gitignored)**: `<pct>_<Name>_diff.png` (amplified difference heatmap),
-`<pct>_<Name>_compare.png` (native ∣ jvm ∣ diff, side by side), and
-`report.txt` ranked worst-first. Windows-only for the native leg today; needs
-Pillow. See `scripts/parity/README.md`.
-
-**What the number means — read this before trusting it.** The `%differ` is the
-fraction of pixels whose per-channel difference exceeds a tolerance. It is NOT
-a pass/fail score and pixel-perfection is not the goal: the two stacks use
-different default fonts, so **every screen carries a steady baseline
-difference** — in the heatmap, text shows as a faint *doubled ghost* from
-slightly different line metrics/baselines. A healthy full sweep is a smooth
-gradient (~2% for a sparse screen like Counter, up to ~32% for a text-dense
-one like Tabs). Known SDL parity gaps also inflate specific screens
-predictably (Brushes ~23% — gradients render solid on SDL; Shadows / Canvas /
-GraphicsLayer — effect differences). **The signal is the RANKING and the
-delta from a screen's own history**, not the absolute value: a text-light
-screen suddenly reading 60%, or a screen jumping far above its neighbours, is
-the bug. In a `_diff.png`: ghosted/doubled text + dark shapes = normal font
-drift; a **solid bright block, or a shape present on only one side** = a real
-regression — open the `_compare.png` to see which stack is wrong.
+See [RENDERER.md](RENDERER.md) for the renderer work these support.
 
 ## Conventions
 

NEXT-SESSION.md

@@ -1,114 +0,0 @@
-# Next session — renderer caching / retained layers
-
-## RESOLVED: the 70-vs-144 "gap" was two monitors, not a bug
-
-The user has a **75 Hz main screen + a 144 Hz second screen**. Each app's FPS is
-just the refresh of whichever monitor its window opened on (SDL locks vsync to
-the window's current display). demo happened to open on the 75 Hz screen,
-apidemo on the 144 Hz one. Move the demo to the 144 Hz screen and it hits ~144.
-
-Instrumentation confirmed there is NO performance problem: both apps have only
-~3.7 ms `draw` per frame (demo geo=40 masks=0; apidemo geo=146 masks=74 —
-apidemo does MORE and is fine), which fits both the 13.3 ms (75 Hz) and 6.7 ms
-(144 Hz) budgets with large headroom. Everything is present/vsync-bound.
-
-**Implication:** the retained-layers / dirty-region / cacheKey work is a
-SPECULATIVE optimization with NO demonstrated need right now — no app misses its
-frame budget. Don't spend the big content-redirect-primitive effort chasing a
-phantom. Revisit only if a real, animated, heavy screen is measured (with
-CDN_PROFILE, ON the target monitor) to exceed its budget.
-
-Still worth doing regardless of perf (correctness / cleanup, small):
-- Delete the dead `cacheKey` scaffolding (`GraphicsLayerModifier` /
-  `GraphicsLayerNode`, unread) OR wire it — and fix the demo's misleading
-  "(cached)" label (it uses a plain `graphicsLayer()`).
-
---- Original investigation notes below (kept for context) ---
-
-
-Starting point after v0.1.19. Context for the perf work the profiling pointed at.
-
-## The problem (measured)
-
-The demo caps at ~70 fps on every screen while apidemo hits 144. Cause is NOT
-vsync (both use `SDL_SetRenderVSync(renderer, 1)`) — the demo is **draw-bound**:
-`CDN_PROFILE=1` showed draw ~34 ms cold / ~14 ms steady, present only ~1.3 ms.
-The renderer is **immediate-mode**: every rendered frame walks the layout tree
-and re-tessellates everything (text → glyph quads, shapes → triangles). The
-always-present sidebar (30+ text rows + icons) is re-tessellated each frame.
-
-Two open threads:
-
-### FINDING (updated) — the 70-vs-144 is NOT reproducible on a 75 Hz dev box
-
-Instrumented the draw phase (`DrawStats`: geo/verts/masks/text/img) + added
-`CDN_FORCERENDER=1`. Measured both apps forced-continuous:
-- demo:    draw ~3.7ms, geo=40,  verts=6582,  masks=0,  text=51
-- apidemo: draw ~2.9ms, geo=146, verts=18576, masks=74, text=174
-BOTH pinned at exactly 150 frames/2s = 75 fps with present ~9ms — i.e. the DEV
-DISPLAY is 75 Hz, so everything is present/vsync-bound here and the demo's draw
-is actually LIGHTER than apidemo's. The "demo is draw-bound" theory is WRONG on
-this hardware; the 70-vs-144 split is specific to the user's 144 Hz monitor and
-can't be reproduced/diagnosed from a 75 Hz box.
-
-NEXT STEP FOR THE USER (144 Hz machine): run both apps with
-`CDN_FORCERENDER=1 CDN_PROFILE=1` and share the `cdn_profile.log` lines. If demo
-shows present ~13ms (75 fps) while apidemo shows present ~7ms (144 fps) at
-similar draw times, it's a present/vsync-path difference (driver / swap
-interval / DWM), NOT draw cost — a different investigation than caching.
-
-The demo idles correctly when static (verified: 2 frames headless, even while
-hovering the sidebar), so there's NO spurious-continuous-render bug — thread A
-below is resolved as a non-issue.
-
-### A. Why does the demo render CONTINUOUSLY? (investigate FIRST — likely cheaper)
-
-Headless the demo idled (2 frames); interactively you see a constant 70-71 fps,
-so something invalidates every frame. Prime suspect: a **hover self-loop** — the
-main loop dispatches a synthetic hover every rendered frame
-(`ComposeWindow.renderFrame`: `if (hasMousePos) host.onPointerRaw(...)`), and if
-that perpetually re-invalidates a hover-reactive sidebar row, the app never
-idles while the cursor is over it. If confirmed, the fix is to stop the spurious
-invalidation so static screens idle (→ sidebar stops re-tessellating because
-nothing renders) — small and targeted, no caching needed.
-- Quick test: does the demo's FPS-title stop updating when the mouse leaves the
-  window? If yes → hover loop confirmed.
-- Look at: `renderFrame` synthetic hover; how hover state feeds `needsFrame` /
-  `hasPendingWork` / `shouldRender()`.
-
-### B. cacheKey / retained-layer texture caching (bigger — the "renderer rewrite")
-
-`Modifier.graphicsLayer(cacheKey=…)` exists as API (`GraphicsLayerModifier` /
-`GraphicsLayerNode` in `element/ModifierElements.kt`) but is **dead
-scaffolding**: `cacheKey` is stored and never read by the renderer; the node is
-a bare `Modifier.Node` with no draw behaviour (comment: "stays dormant until the
-renderer rewrite drives it"). The demo's GraphicsLayer "(cached)" section uses a
-plain `graphicsLayer()` — the label is aspirational; nothing is cached.
-
-Blocker for real texture caching: it needs to render a subtree's `drawContent()`
-into an **offscreen canvas**, and the renderer has no way to redirect
-`drawContent()` off the frame canvas. `GraphicsLayer.native.draw()` replays its
-recorded block against a canvas via `drawScope.draw(…, canvas, …)`, but
-`drawContent()` is bound to the outer `ContentDrawScope`'s canvas, which nothing
-swaps. The vector/icon offscreen path works only because it draws an explicit
-object, not opaque `drawContent()`.
-
-So the real unit of work is a **content-redirect primitive**: make the
-`ContentDrawScope` canvas swappable (or add a coordinator-level "draw this
-subtree into canvas X"). That primitive is the foundation for BOTH cacheKey
-(retained layers) AND dirty-region rendering. Infrastructure that already
-exists to build on: `OffscreenRenderer` (`createImageBitmap` + `createCanvas`),
-`SdlImageBitmap` render-target textures + `drawImage` blit-back, and the
-`NativeReleaseQueue` for freeing cached textures.
-
-Cleanup to do regardless: either implement `cacheKey` or delete the dead
-`GraphicsLayerModifier`/`GraphicsLayerNode` scaffolding and fix the demo's
-misleading "(cached)" label.
-
-## Tooling ready for this work
-
-- `CDN_PROFILE=1 <app>` → per-phase timings (layout/draw/present) to a file.
-- `scripts/parity/parity.py` → native-vs-JVM screenshot diff (regression net).
-- `scripts/probe/probe.py` → drive a native window (click/hover/hold) + capture.
-- See ROADMAP.md item 2 (dirty regions + retained layers promoted, with the
-  demo evidence) and CLAUDE.md "Tooling".

README.md

@@ -1,283 +1,180 @@
 [![Kotlin](https://img.shields.io/badge/Kotlin-2.4.0-blue.svg?style=flat&logo=kotlin)](https://kotlinlang.org)
+[![License: MIT](https://img.shields.io/badge/License-MIT-green.svg)](LICENSE.md)
 
 # Compose Desktop Native
 
-A Kotlin/Native port of **Compose Multiplatform** running on **SDL3** for
-windowing and input — **no JVM**. Compiles to native binaries for macOS
-(arm64), Linux (x64/arm64), Windows (mingwX64).
+Run [Compose Multiplatform](https://github.com/JetBrains/compose-multiplatform)
+as a native binary, with no JVM. Compose Desktop Native compiles to a single
+executable for macOS (arm64), Linux (x64/arm64), and Windows (mingwX64), using
+[SDL3](https://libsdl.org) for windowing and input.
 
-Rendering is pluggable behind one `RenderBackend`:
+<img src="screenshots/demo.png" width="100%" alt="Compose Desktop Native demo" />
 
-- **Skia** (via Skiko klibs) on macOS + Linux — Metal / OpenGL / CPU raster.
-- **SDL3** (`SDL3_ttf` + `SDL_RenderGeometry`) on Windows, and on macOS/Linux
-  when `-Prenderer=sdl3` is passed.
+## How it works
 
-The Compose **runtime** is the official
-`org.jetbrains.compose.runtime:runtime` klibs from Maven — this project
-re-implements the layers on top of it (`androidx.compose.ui.*`,
-`.foundation.*`, `.animation.*`, `.material3.*`) by **vendoring
-upstream Compose Multiplatform verbatim** whenever possible and hand-rolling
-project actuals + SDL3 / Skia glue only where needed.
+- **The runtime is the real one.** Composition, snapshots, and the recomposer
+  are the official `org.jetbrains.compose.runtime` klibs from Maven, never
+  reimplemented.
+- **The UI layers are vendored upstream.** `androidx.compose.ui`, `foundation`,
+  `animation`, and `material3` are copied from Compose Multiplatform verbatim
+  wherever they compile as is, with project code filling in only the native glue.
+- **Rendering is pluggable** behind one `RenderBackend`: Skia (via Skiko) on
+  macOS and Linux, and a from-scratch SDL3 renderer (`SDL3_ttf` +
+  `SDL_RenderGeometry`) on Windows, or anywhere with `-Prenderer=sdl3`.
+- **The platform is SDL3.** Windowing, input, audio, filesystem, file dialogs,
+  and clipboard all go through SDL3, so one code path covers every OS.
+- **No runtime dependencies.** SDL3 and its codecs are built as static
+  libraries and linked in. A distributable is just the executable plus a
+  `data.kres` resource bundle.
 
-## Module layout
+| Platform | Gradle target | Default renderer |
+|----------|---------------|------------------|
+| macOS arm64 | `macosArm64` | Skia (Metal) |
+| Linux x64 / arm64 | `linuxX64` / `linuxArm64` | Skia (OpenGL) |
+| Windows | `mingwX64` | SDL3 |
 
-One Gradle module per upstream Compose artifact — the directory tree mirrors
-upstream's `compose/` layout, gradle paths stay short via `projectDir`
-redirects.
+## Quickstart
 
-```
-compose/
-├── ui/
-│   ├── ui/               → :ui              (androidx.compose.ui.* + renderers + cinterops)
-│   ├── ui-util/          → :ui-util
-│   ├── ui-geometry/      → :ui-geometry
-│   ├── ui-unit/          → :ui-unit
-│   ├── ui-backhandler/   → :ui-backhandler
-│   └── ui-tooling-preview/ → :ui-tooling-preview (common @Preview + PreviewParameterProvider —
-│                                             IDE-only metadata; previews render via the apps' jvm targets)
-├── animation/
-│   ├── animation-core/   → :animation-core
-│   ├── animation/        → :animation
-│   └── animation-graphics/ → :animation-graphics
-├── foundation/
-│   ├── foundation/       → :foundation
-│   └── foundation-layout/ → :foundation-layout
-├── material3/material3/  → :material3
-├── material/material-ripple/ → :material-ripple
-└── sdl/                  (project modules — the SDL integration layer)
-    └── window/           → :window          (nativeComposeApp { Window(...) } + SDL3 main loop,
-                                              per-window Lifecycle/ViewModelStore/SavedState owners)
-
-utils/
-└── material-symbols/    → :material-symbols (Material Symbols: 4200+ codepoints + Outlined/Rounded/
-                                              Sharp composables with the variable-font axes as
-                                              parameters (FILL/wght/GRAD/opsz). Common API — native
-                                              draws via the port's icon-font engine, the jvm target
-                                              via Skiko, so shared app code uses it on both stacks)
-
-components/
-└── resources/library/    → :components-resources (vendored official compose resources runtime —
-                                              painterResource/stringResource/Res codegen; the Maven
-                                              artifact ships no mingwX64/linux klibs)
-
-navigation3/
-└── navigation3-ui/       → :navigation3-ui  (vendored NavDisplay + scene machinery — the one
-                                              Navigation 3 layer without a K/N desktop artifact)
-
-gradle-plugin/
-└── compose-desktop-native-bridge/ → :compose-desktop-native-bridge (the consumer-side bridge, published
-                                              as a Gradle plugin — see "Using it from your own build")
-
-demo/     → :demo     (showcase + CLI probe suite; multiplatform — the same screens
-                       also build for stock JVM Compose Desktop as a parity reference)
-apidemo/  → :apidemo  (Postman-style REST client; multiplatform — same UI on JVM too)
-```
-
-## demo — widget & feature showcase
-
-<img src="screenshots/demo.png" width="100%" alt="ComposeNativeSDL3 demo" />
-
-`:demo` is a full tour of the re-implemented Compose + Material 3 surface —
-30+ sidebar screens covering buttons, text fields, layout, modifiers, shapes,
-images, state & recomposition, scrolling & lazy lists, dialogs, icons, canvas,
-graphics layers, custom layout, animation and gestures.
-
-```bash
-./gradlew :demo:runDebugExecutableMacosArm64      # macOS  (Skia / Metal)
-./gradlew :demo:runDebugExecutableLinuxX64        # Linux  (Skia / OpenGL)
-gradlew.bat :demo:runDebugExecutableMingwX64      # Windows (SDL3)
-./gradlew :demo:run                               # stock JVM Compose Desktop (parity reference)
-```
-
-The same shared screens drive both stacks — the JVM target runs them on
-upstream Compose Desktop unchanged, so any visual or behavioural difference
-against the native build is a porting bug, not a demo artifact.
-
-CLI: `--gpu=…`, `--screen=<Name>` (one screen, no sidebar),
-`--screenshot=out.bmp --frames=N`, `--width=W --height=H`.
-
-## apidemo — API Manager
-
-<img src="screenshots/apidemo.png" width="100%" alt="ComposeNativeSDL3 API Manager" />
-
-`:apidemo` is a Postman-style REST client built entirely on the library:
-request collections (**packs**, nested sub-packs, linked copies), a
-**Session → Pack → Request** inheritance ladder for variables / headers /
-query params / client certs, syntax-highlighted JSON / XML / YAML / HTML body
-editors, a response viewer with timing, size and TLS-chain inspection, mTLS
-client certificates, drag-and-drop tree management, request history and
-file-based sessions.
-
-```bash
-./gradlew :apidemo:runDebugExecutableMacosArm64
-./gradlew :apidemo:runDebugExecutableLinuxX64
-gradlew.bat :apidemo:runDebugExecutableMingwX64
-./gradlew :apidemo:run                            # stock JVM Compose Desktop (parity reference)
-```
-
-Like the demo, the whole UI lives in `commonMain` and also runs on upstream
-Compose Desktop (JVM); only the mTLS / TLS-chain features are native-only —
-they drive the bundled libcurl directly.
-
-Add `-Prenderer=sdl3` on macOS/Linux to drop Skiko and use the pure-SDL3
-renderer everywhere.
-
-## Minimal app
+### A window
 
 ```kotlin
 import androidx.compose.material3.Text
 import com.compose.sdl.nativeComposeWindow
 
 fun main() = nativeComposeWindow(title = "Hello") {
-    Text("Hello from ComposeNativeSDL3")
+    Text("Hello from Compose Desktop Native")
 }
 ```
 
-The lambda runs with a `ComposeWindowScope` receiver exposing
-`window: ComposeNativeWindow` (`setTitle` / `setSize` / `minimize` /
-`maximize` / `setFullscreen` / `close` / …); the same handle is reachable
-from any nested composable via `LocalComposeNativeWindow.current`.
+The content lambda runs with a `ComposeWindowScope` receiver that exposes
+`window: ComposeNativeWindow` (`setTitle`, `setSize`, `minimize`, `maximize`,
+`setFullscreen`, `close`). The same handle is reachable from any nested
+composable via `LocalComposeNativeWindow.current`.
 
-Add these to your module's `commonMain.dependencies`:
+For multiple windows, wrap them in `nativeComposeApp`, where the set of
+`Window(...)` calls is state driven (Compose Desktop style):
 
 ```kotlin
-implementation(project(":window"))            // window + main loop
-implementation(project(":material3"))         // Material 3 widgets
-implementation(project(":material-symbols"))  // icon-font composables (optional)
+fun main() = nativeComposeApp {
+    Window(title = "Main", onCloseRequest = ::exitApplication) { /* ... */ }
+    if (showInspector) {
+        Window(title = "Inspector", onCloseRequest = { showInspector = false }) { /* ... */ }
+    }
+}
 ```
 
-## Using it from your own build — the bridge plugin
+Each window gets its own `Lifecycle`, `ViewModelStore`, and `SavedStateRegistry`
+owners, driven by real SDL focus and visibility events, so ViewModels and
+saved state behave as they do on Android.
 
-The klibs publish to GitHub Packages under `com.bitsycore.compose.sdl:*`, and
-a companion Gradle plugin ships the "redirect trick" this repo uses
-internally: apply **`com.bitsycore.compose-desktop-native.bridge`** once in
-`settings.gradle.kts` and declare the **official Compose Multiplatform
-coordinates** in `commonMain` — the plugin substitutes the port's klibs on
-every native desktop configuration (mingwX64 / linuxX64 / linuxArm64 /
-macosArm64), while android / jvm / iOS / wasm keep resolving the official
-artifacts. One dependency list, all CMP platforms + the port's new ones.
+### Building in this repo
 
 ```kotlin
-// settings.gradle.kts
-plugins { id("com.bitsycore.compose-desktop-native.bridge") version "<release>" }
-
-// build.gradle.kts — official coords, everywhere
 commonMain.dependencies {
-    implementation("org.jetbrains.compose.runtime:runtime:<runtime-version>")
-    implementation("org.jetbrains.compose.ui:ui:<cmp-version>")
-    implementation("org.jetbrains.compose.foundation:foundation:<cmp-version>")
-    implementation("org.jetbrains.compose.material3:material3:<cmp-m3-version>")
+    implementation(project(":window"))           // window shell + main loop
+    implementation(project(":material3"))        // Material 3 widgets
+    implementation(project(":material-symbols")) // icon-font composables (optional)
 }
 ```
 
-Setup details (repositories, credentials, version pinning):
+### Building from your own project: the bridge plugin
+
+The klibs publish to GitHub Packages under `com.bitsycore.compose.sdl:*`. Apply
+the bridge Gradle plugin once, declare the **official** Compose Multiplatform
+coordinates, and the plugin swaps in the port's klibs on native desktop targets
+while android, jvm, iOS, and wasm keep resolving the official artifacts.
+
+```kotlin
+// build.gradle.kts, official coordinates everywhere
+plugins {
+    kotlin("multiplatform")
+    id("org.jetbrains.compose")
+    id("com.bitsycore.compose-desktop-native.bridge") version "<release>"
+}
+
+commonMain.dependencies {
+    // The plugin exposes the exact Compose versions the port tracks, so you
+    // never hand-match them (material3 is versioned separately upstream).
+    implementation("org.jetbrains.compose.runtime:runtime:${composeDesktopNative.composeRuntime}")
+    implementation("org.jetbrains.compose.ui:ui:${composeDesktopNative.compose}")
+    implementation("org.jetbrains.compose.foundation:foundation:${composeDesktopNative.compose}")
+    implementation("org.jetbrains.compose.material3:material3:${composeDesktopNative.composeMaterial3}")
+}
+```
+
+Repositories, credentials, and version pinning:
 [gradle-plugin/compose-desktop-native-bridge/README.md](gradle-plugin/compose-desktop-native-bridge/README.md).
 
+For a complete project that applies the bridge and builds one shared UI for
+Android, JVM, and native desktop, see the example repo:
+[bitsycore/compose-desktop-native-bridge-example](https://github.com/bitsycore/compose-desktop-native-bridge-example).
+
+## Sample apps
+
+Both live in `commonMain` and also build for stock JVM Compose Desktop, which
+serves as the visual and behavioural reference: any difference against the
+native build is a porting bug.
+
+**`:demo`** is a tour of the re-implemented Compose and Material 3 surface,
+30-plus screens covering text, layout, shapes, images, state, lazy lists,
+dialogs, canvas, graphics layers, animation, and gestures.
+
+```bash
+./gradlew :demo:runDebugExecutableMacosArm64   # macOS (Skia / Metal)
+./gradlew :demo:runDebugExecutableLinuxX64     # Linux (Skia / OpenGL)
+gradlew.bat :demo:runDebugExecutableMingwX64   # Windows (SDL3)
+./gradlew :demo:run                            # JVM Compose Desktop (reference)
+```
+
+**`:apidemo`** is a Postman-style REST client built entirely on the library:
+request collections, a session inheritance ladder, syntax-highlighted body
+editors, a response viewer with timing and TLS-chain inspection, and mTLS
+client certificates.
+
+<img src="screenshots/apidemo.png" width="100%" alt="Compose Desktop Native API Manager" />
+
+```bash
+./gradlew :apidemo:runDebugExecutableMacosArm64
+./gradlew :apidemo:run                         # JVM Compose Desktop (reference)
+```
+
+Pass `-Prenderer=sdl3` on macOS or Linux to drop Skiko and use the pure SDL3
+renderer everywhere.
+
+## Modules
+
+One Gradle module per upstream Compose artifact, mirroring the upstream
+`compose/` tree. The renderer and cinterops live in `:ui`; `:window` is the SDL
+integration layer. `:material-symbols`, `:components-resources`, and
+`:navigation3-ui` are project or vendored modules that the official Maven
+artifacts do not cover for Kotlin/Native desktop.
+
+Most of the androidx architecture stack (lifecycle, viewmodel, navigation3,
+savedstate, navigationevent) ships real Kotlin/Native desktop klibs and runs on
+the port unmodified. The full module map, dependency graph, and the list of
+compatible artifacts are in [CLAUDE.md](CLAUDE.md).
+
 ## Building
 
-All four native dependencies — **SDL3**, **SDL3_ttf** (the in-house
-variable-font-axes fork), **SDL3_image** (+ vendored PNG/WEBP codecs) and
-**FreeType** — are built from source as **static** libraries by one script,
-on every OS, and linked straight into the executable. No `brew install`, no
-`apt install libsdl3-dev`, no runtime `.dll` / `.so` / `.dylib` next to the
-binary — a distributable is just `<app>` + `data.kres`.
+Build the native libraries once per machine, then build any app target:
 
 ```bash
-python3 scripts/build-sdl/build-all.py            # freetype → sdl3 → sdl3-image → sdl3-ttf
-python3 scripts/build-sdl/build-all.py sdl3-ttf   # rebuild a subset
+python3 scripts/build-sdl/build-all.py         # SDL3, SDL3_ttf, SDL3_image, FreeType (static)
+./gradlew :demo:runDebugExecutableMacosArm64
 ```
 
-Library versions / URLs are pinned in `scripts/build-sdl/build-sdl.properties`;
-output lands in the gitignored in-repo `libs/`. Required on every host: `git`,
-`cmake`, Python 3 (`ninja` is fetched automatically when absent). Per host:
+Every host needs `git`, `cmake`, and Python 3. Per host: macOS needs the Xcode
+command line tools; Linux needs gcc/g++ and the X11 / Wayland / audio dev
+headers; Windows needs a mingw-w64 g++ on PATH. See [TOOLING.md](TOOLING.md) for
+the full build and verification workflow.
 
-- **macOS** — Xcode command line tools. Skia is the default renderer; Skiko
-  klibs come from Maven.
-- **Linux** — gcc/g++ plus the X11 / Wayland / audio dev headers SDL3's
-  configure detects (the exact apt list is in
-  `.github/workflows/publish.yml`).
-- **Windows** — a mingw-w64 g++ on PATH (the C side compiles with
-  Kotlin/Native's bundled mingw).
+## Documentation
 
-Then build any app target — see the demo / apidemo commands above.
-
-## Vendoring
-
-The bulk of the `androidx.compose.*` code is vendored byte-for-byte from
-`JetBrains/compose-multiplatform-core` and lives under
-`<module>/src/vendor/` (gitignored — you re-sync on demand). Each module
-carries a `compose-fork.txt` manifest listing which upstream files it pulls
-in.
-
-```bash
-scripts/compose-fork/sync.sh                           # sync every module
-scripts/compose-fork/sync.sh compose/ui/compose-fork.txt   # one module
-```
-
-Upstream ref pinned in `scripts/compose-fork/compose.properties`; manifests can
-pin additional upstream repos inline (`SET_REPO=<url>@<ref>` — the resources
-runtime vendors from the compose-multiplatform umbrella repo this way).
-
-How much of upstream's public API the port actually covers is measured, not
-guessed — `scripts/compose-coverage.py` diffs this repo's klib ABI dumps
-against upstream's, per vendored module:
-
-```bash
-./gradlew apiDump && python3 scripts/compose-coverage.py   # per-module coverage tables
-python3 scripts/compose-coverage.py --missing ui-text      # list the exact uncovered decls
-```
-
-See [CLAUDE.md](CLAUDE.md) for the full architecture, source-set hierarchy,
-vendoring rules, density flow (physical-pixel Option B), and per-area file
-map.
-
-## Known Compatible — official artifacts that just work
-
-A surprising amount of the androidx architecture stack ships real
-Kotlin/Native desktop klibs (mingwX64, linuxX64/arm64, macosArm64) and runs
-on this port **unmodified** — no reimplementation, no vendoring. Sometimes
-the Google coordinates (`androidx.*`) carry the K/N variant, sometimes the
-JetBrains ones (`org.jetbrains.*`) — check both.
-
-Verified working in-tree:
-
-| Artifact                                                        | Notes                                                                                      |
-|-----------------------------------------------------------------|--------------------------------------------------------------------------------------------|
-| `org.jetbrains.compose.runtime:runtime`, `runtime-saveable`     | the Compose runtime itself — never reimplemented                                           |
-| `androidx.compose.runtime:runtime-retain`                       | google coordinates                                                                         |
-| `androidx.lifecycle:lifecycle-runtime-compose`                  | `LocalLifecycleOwner`, `rememberLifecycleOwner`, `repeatOnLifecycle`                       |
-| `androidx.lifecycle:lifecycle-viewmodel(-compose, -savedstate)` | full ViewModel + SavedStateHandle stack                                                    |
-| `androidx.lifecycle:lifecycle-viewmodel-navigation3`            | per-entry ViewModel scoping for Navigation 3                                               |
-| `androidx.savedstate:savedstate`, `savedstate-compose`          |                                                                                            |
-| `androidx.navigation3:navigation3-runtime`                      | backstack / NavEntry / decorators (only the UI layer needed vendoring → `:navigation3-ui`) |
-| `androidx.navigationevent:navigationevent-compose`              | predictive back / BackHandler plumbing                                                     |
-| `androidx.collection:collection`                                |                                                                                            |
-
-The window layer supplies what these expect from a host: per-window
-`LifecycleOwner` (driven by real SDL focus/visibility events — focused →
-RESUMED, unfocused → STARTED, minimized → CREATED), `ViewModelStoreOwner`
-(the `activityViewModels()` analog, `SavedStateHandle`-enabled) and
-`SavedStateRegistryOwner`, plus a `Dispatchers.Main` with a true `immediate`.
-ViewModels scope per nav entry, per window, or anywhere in between — same
-semantics as Android.
-
-## Tooling
-
-Helper scripts live under `scripts/`; each has its own README with detail.
-
-| Tool | Use it to | More |
-|------|-----------|------|
-| `scripts/build-sdl/build-all.py` | build the static SDL3 / TTF / image / FreeType libs | see **Building** above |
-| `scripts/compose-fork/sync.sh` | re-sync the vendored upstream Compose sources | [README](scripts/compose-fork/README.md) |
-| `scripts/parity/parity.py` | diff every demo screen native-vs-JVM to catch render regressions | [README](scripts/parity/README.md) |
-| `scripts/probe/probe.py` | drive a native window (click/hover/hold) + screenshot it | [README](scripts/probe/README.md) |
-| `CDN_PROFILE=1 <app>` | print per-phase frame timings to find slow frames | — |
-| `python scripts/compose-coverage.py` | measure API coverage vs upstream (after `./gradlew apiDump`) | — |
-
-Building on the port from another project? Use the bridge plugin —
-[gradle-plugin/compose-desktop-native-bridge](gradle-plugin/compose-desktop-native-bridge/README.md).
-Contributor-facing detail (including how to read the parity `%differ`) is in
-[CLAUDE.md](CLAUDE.md#tooling--whats-available-and-when-to-reach-for-it).
+- [TOOLING.md](TOOLING.md): building the native libs, vendoring, and verification.
+- [CLAUDE.md](CLAUDE.md): architecture, source-set hierarchy, vendoring rules,
+  density flow, and a per-area file map.
+- [gradle-plugin/compose-desktop-native-bridge](gradle-plugin/compose-desktop-native-bridge/README.md):
+  consuming the port from another build.
 
 ## License
 

RENDERER.md

@@ -0,0 +1,263 @@
+# RENDERER.md
+
+The durable reference for the rendering layer: how it is structured, the
+convergence work that shaped it, the decisions worth remembering, and what is
+left. Read this before touching anything under `renderer/`, the graphics
+actuals, or the layer engine.
+
+For build and verification commands see [TOOLING.md](TOOLING.md). For module
+layout, source-set hierarchy, and vendoring rules see [CLAUDE.md](CLAUDE.md).
+
+## 1. The two renderer legs
+
+Rendering is pluggable behind one `RenderBackend` interface. Exactly one leg is
+active per target:
+
+- **Skia leg** (`skikoRendererMain`, macOS + Linux). Draws through upstream
+  Compose Multiplatform's own Skia stack, vendored verbatim: `SkiaBackedCanvas`,
+  `SkiaBackedPaint`, `SkiaShader`, `actual class GraphicsLayer` backed by
+  `org.jetbrains.skiko.node.RenderNode`, `SkiaGraphicsContext`. On this leg the
+  layer and draw engine internals are literally upstream.
+- **SDL leg** (`sdlRendererMain`, Windows always; macOS/Linux under
+  `-Prenderer=sdl3`). A from-scratch renderer on `SDL_RenderGeometry` +
+  `SDL3_ttf` + FreeType. SDL is a triangle blitter, so this leg carries a
+  permanent bespoke surface (about 3,800 lines): `Sdl3Canvas`,
+  `Sdl3TextRenderer`, `FreeTypeIcons`, and the SDL render nodes.
+
+Both legs share one project-owned text and image pipeline (`SdlParagraph`,
+`NativeTextMeasurer`, `IconFont`). Text layout, line-breaking, metrics, and
+hit-test are the port's engine on both legs; only glyph rasterization differs
+(Skia vs SDL3_ttf/FreeType). This is a deliberate axiom, not a gap: see the
+text decision in section 4.
+
+The seam is kept as narrow and low as possible. Code flows
+`Common (upstream) -> shared native engine -> Skia actual / SDL actual`. What we
+minimize is hand-rolled actual surface, not actual-side line count: a fat
+vendored-upstream actual (the Skia leg carrying upstream's whole GraphicsLayer
+stack) is preferred over a thin hand-written one.
+
+## 2. The retained-layer engine (the model we copied)
+
+Upstream skiko skips work at three levels. The port has all three.
+
+- **L1 frame scheduling.** A frame schedules the next only if still dirty.
+  Ours: `ComposeWindow.shouldRender()` gates `renderFrame()`; the loop blocks on
+  `SDL_WaitEventTimeout` when idle.
+- **L2 measure/layout only dirty nodes.** Vendored `MeasureAndLayoutDelegate`
+  used verbatim through `ComposeOwner.measureAndLayout()`.
+- **L3 draw record-once / replay** (the expensive one). Each isolated
+  `LayoutNode` gets an `OwnedLayer` (`GraphicsLayerOwnerLayer`) owning a
+  `GraphicsLayer`. The display list re-records only when content is dirty;
+  otherwise it replays.
+
+The critical property: **transform, alpha, and clip changes do NOT re-record.**
+Moving, scaling, rotating, or fading a layer replays cached content under a new
+transform. Only a genuine content change (a state read inside the draw block, or
+a resize) re-records. Upstream replays the whole scene every frame with no
+dirty-region present; the entire win is not re-recording clean layers, not
+drawing less screen. Dirty-region rendering is therefore an explicit non-goal.
+
+The compositing-strategy contract (`requiresLayer()`, from
+`SkiaGraphicsLayer.skiko.kt`) must match on both legs. It decides when a layer
+needs an offscreen:
+
+| Condition | Auto | Offscreen | ModulateAlpha |
+|---|---|---|---|
+| `alpha < 1` | offscreen | offscreen | per-op alpha multiply (no offscreen) |
+| `colorFilter != null` | offscreen | offscreen | offscreen |
+| `blendMode != SrcOver` | offscreen | offscreen | offscreen |
+| `renderEffect != null` | offscreen | offscreen | offscreen |
+| none of the above | replay in place | always offscreen | replay in place |
+
+## 3. Current state
+
+- **Skia leg runs upstream's engine.** Canvas (`SkiaBackedCanvas`) and
+  GraphicsLayer/GraphicsContext (`org.jetbrains.skiko.node.RenderNode`) are
+  vendored verbatim. The Skia leg gets real display-list caching and correct
+  clip/shadow/renderEffect for free from upstream. After this landed, Skia
+  `draw` on LazyColumn fell from 1.75 ms to 0.2 ms.
+- **SDL leg ships the geo node as the Windows default.** `SdlDisplayListRenderNode`
+  records a leaf's layer-local tessellated geometry, text runs, and icon glyphs
+  by params (not texture pointers), then re-emits through the layer transform.
+  Crisp under any transform, bit-exact, deterministic (no render-target state),
+  and eviction-safe (replay re-looks-up via the run LRU / FreeType glyph cache).
+  0.000% across a 57-screen self-consistency sweep bar a sub-0.06% rotated-edge
+  AA fringe. LazyColumn steady-state `draw` fell 57% versus the un-cached
+  baseline. Fallbacks: `CDN_LAYERCACHE=off|texture`.
+- **Parity is a golden-master on the Skia leg** (about 2% median, dominated by
+  the shared text engine's small metric delta) and a bounded, ranked signal on
+  the SDL leg. See TOOLING.md for how to read it.
+- **Memory is stable.** The historical composition leak is fixed (see section 6)
+  and guarded by the `--soaktest` gate in the verify runbook.
+
+## 4. Decisions to remember
+
+- **Goal is G1, cheap upstream-tracking.** The target is low per-bump
+  reconciliation cost when following upstream, not Windows pixel-parity or
+  feature completeness. The JVM Compose Desktop target (`:demo:run`) is the
+  documented Windows fidelity/feature tier: real Skia, full fidelity, on any
+  host. That makes SDL-leg fidelity work (B3) and real-Skia-on-Windows (Track A)
+  optional polish, not obligations.
+- **Vendor, do not hand-roll.** Copy upstream verbatim wherever it compiles.
+  Edit-to-compile becomes a manual vendor with a `// VENDOR-BASE:` header so the
+  drift tripwire can track it. The litmus test for any divergence: "Is this what
+  upstream does? If not, what real platform constraint forces the difference?"
+  Valid answers name a constraint (no Skiko on Windows K/N; SDL is a triangle
+  blitter). "It was easier" is not valid.
+- **B2 convergence is complete.** The Skia leg was migrated off the port's
+  hand-rolled GraphicsLayer onto upstream's own. This was a source-set migration,
+  not a file-flip: the SDL node cluster relocated `nativeMain -> sdlRendererMain`,
+  `GraphicsContext` forked per-leg behind a `createGraphicsContext()` seam, and
+  the upstream skiko files were un-refused in `compose-fork.txt`. Measured
+  sync-tax reduction on the skiko path: about 8.5x (roughly 1240 hand-rolled
+  lines down to about 145 lines of drift-tracked edits; roughly 1006 lines now
+  auto-sync verbatim on a ref bump). The beta02 -> beta03 bump proved it: zero
+  reconciliation, all manual-vendor bases unchanged.
+- **Text stays the port's engine (B6.3 skipped).** Making Skia-leg text truly
+  upstream (`SkiaParagraph`) is a font-subsystem replacement, not a canvas swap:
+  two coexisting font-identity models (the port's name-to-bytes `IconFont` +
+  no-op resolver vs upstream `PlatformFont`/`FontCache`/`FontCollection`), about
+  13 skiko files to re-vendor, about 10 shared actuals to split, a
+  `data.kres`-to-`FontCache` bridge, no green intermediate, and it discards the
+  P3.1 metrics work. ROI is low: the Skia leg already measures text with skiko
+  `Font` metrics (via `currentTextMeasurer` -> `SkiaTextRenderer`), which is how
+  parity reached about 2%. Revisit only if complex-script/bidi fidelity on the
+  native Skia leg becomes a hard requirement.
+- **`GraphicsLayerOwnerLayer` stays shared.** The fork point is `GraphicsLayer` /
+  `GraphicsContext`, not the owner layer. The shared owner layer compiles
+  against both `GraphicsLayer` actuals (upstream skiko + port SDL) only if both
+  satisfy the commonMain `expect class GraphicsLayer` API. That API-parity
+  invariant is enforced by `:ui:compileCommonMainKotlinMetadata` on every build.
+- **Lifetime model.** The SDL leg uses GC / release-queue for layer lifetime and
+  does NOT vendor `ChildLayerDependenciesTracker`. The Skia leg uses upstream's
+  `SkiaGraphicsLayer`, which inherently uses the tracker (already vendored in
+  commonMain). A per-leg lifetime divergence is the class of bug that caused an
+  early navigation crash, so any change here goes to both legs plus a soak gate.
+- **Module split (`:ui-graphics` / `:ui-text`) is shelved as infeasible.** Not
+  cosmetic churn as originally scoped: the `sdl3` cinterop is a shared substrate
+  used by 11 graphics-side files AND 12 platform/windowing/node/resources files
+  that stay in `:ui`. Kotlin/Native cannot cleanly share a cinterop klib across a
+  module boundary, which is exactly why they were merged. A real split needs a
+  new non-upstream `:ui-cinterop` base module plus cross-module cinterop
+  api-exposure, which is bigger and more divergent than the "match upstream
+  artifacts" goal it was meant to serve. The one keeper from the attempt:
+  `RenderBackend.drawRoot` now takes `(Canvas) -> Unit`, decoupling the backends
+  from `ComposeRootHost` (a genuine improvement, retained).
+- **Track A (real Skia on Windows K/N) is shelved.** Kotlin/Native mingwX64 is
+  GNU-ABI; skia-pack Windows is MSVC-ABI, which cannot be statically fused into a
+  GNU-ABI binary. Building current C++20 Skia to a GNU/mingw static archive is an
+  open-ended fork (only abandoned Mozilla-era precedent). The only working route
+  is a runtime DLL, which breaks the no-DLL invariant and adds tens of MB on the
+  one platform it targets. The SDL leg is the permanent Windows renderer; JVM is
+  the fidelity escape hatch.
+
+## 5. Convergence status
+
+| Item | Status |
+|------|--------|
+| Guardrails (parity gate, verify-mac runbook, drift + vendor-clean checks) | Done |
+| B2: Skia leg on upstream GraphicsLayer/GraphicsContext | Done |
+| B6.1: Skia leg on upstream `SkiaBackedCanvas` + paint/shader | Done |
+| B6.2: upstream `GraphicsLayer` + delete transient port cluster | Done |
+| B6.3: upstream text (`SkiaParagraph`) on the Skia leg | Skipped (decision) |
+| B5: engine-convergence deltas audit | Done (clean wins spent by B6) |
+| P2.2: composition memory leak | Fixed + soak-gated |
+| P2.3: outsets / blur / renderEffect | Done via upstream `SkiaGraphicsLayer` |
+| P3.1: SDL text metrics parity (17% median -> 2%) | Done |
+| B3: further SDL fidelity | Capped (parity-ranked wins only) |
+| Module split | Shelved (infeasible as specified) |
+| Track A: real Skia on Windows | Shelved |
+
+## 6. Remaining and future work
+
+Nothing here blocks day-to-day work. These are the open threads worth
+remembering.
+
+- **WIN-SMOKE (pre-ship, Windows only).** The Mac runbook covers both renderers
+  but cannot cover the shipped mingwX64 binary, the Windows-only `PrintWindow`
+  probe, or the common-metadata publish job. Run these on a Windows host before
+  any release. This is the only outstanding verification.
+- **Stabilization at Compose 1.12.0 stable.** The vendored refs are pinned to
+  `v1.12.0-beta03+dev4483` (no clean beta03 tag exists yet, and it is not on
+  Maven). The native side leads the JVM parity leg (forced to beta02, the latest
+  published) by a documented skew. When 1.12.0 stable ships: re-pin both refs to
+  the clean tag, bump the `vComposeJvmVersion` forcing in demo/apidemo/
+  material-symbols to close the skew, then cut the release. The concrete
+  step-by-step (the version map, the ref-bump flow, and the release flow) lives
+  in [TOOLING.md](TOOLING.md#versioning-and-releasing).
+- **Deferred engine deltas (D2-D6, all low ROI under G1).**
+  - D2: split `GraphicsLayerOwnerLayer` per-leg to restore upstream's exact
+    `setLightingInfo` shadow lighting. Feasible (the old RootNodeOwner-coupling
+    blocker was outdated) but high blast radius for a marginal gain; elevation
+    shadows already match JVM.
+  - D3: dedupe `LayerTransformationMatrix.kt` against the now-vendored
+    `Matrices.skiko`. Blocked on D2 (the shared owner-layer hit-test needs a
+    both-legs matrix fn).
+  - D4/D5: `SemanticsRegion` intersect/difference are stubs, and `CharHelpers`
+    is naive grapheme/bidi vs upstream ICU. Real fidelity gaps, gated on an
+    accessibility or complex-script roadmap.
+  - D6: `Focusability` / `PlatformVelocityTracker` are byte-equal to upstream;
+    vendoring them saves nothing.
+- **SDL performance (opportunistic).** Shared glyph atlas to replace per-run
+  textures; `drawImageRect` capture in the geo node (journal rates it low-ROI).
+- **SDL_GPU backend (long-term).** Real stencil clipping, pipelined batching,
+  shader gradients. The `NativeRenderNode` seam makes a GPU node a clean
+  drop-in.
+- **Native-resource lifecycle.** Wire `GraphicsLayer`/RenderNode +
+  `SdlImageBitmap.close()` fully into cache eviction and the renderer
+  `destroy()` chain; demote the periodic GC nudge once ownership covers it.
+
+## 7. Hard-won learnings (do not relearn)
+
+- **Minimize-divergence is load-bearing.** A hand-written `notifyLayerIsDirty`
+  that diverged from upstream `OwnedLayerManagerImpl` removed a layer from
+  `dirtyLayers` mid-loop and crashed on any navigation. Screenshots missed it;
+  the interaction probe caught it. Match upstream verbatim; do not hand-roll
+  engine plumbing from a summary.
+- **The composition memory leak (root cause).** The port never called
+  `OwnerSnapshotObserver.clearInvalidObservations()`, which upstream
+  `RootNodeOwner` runs after every measure. Snapshot read-observations for
+  scopes invalidated on dispose lingered forever, each pinning its observed
+  object graph via a Kotlin/Native `ExternalRCRef` (a K/N-heap leak, vmmap
+  Memory Tag 246). Most visible on ripple/indication draws. Fix:
+  `ComposeRootHost.measureAndLayout()` sweeps `clearInvalidObservations()` after
+  layout, plus `ComposeOwner.onDetach` clears the detached node's observations.
+  Found by exact live-counters, static-mode isolation, macOS `leaks`/`heap`/
+  `vmmap`, and component bisection. RSS alone cannot pinpoint a referenced leak;
+  budget heap tooling for this class.
+- **Offscreen-texture caching is timing-nondeterministic on complex screens.**
+  This is why the geo (no-render-target) node is the robust default, not the
+  texture node.
+- **Rounded/path layer clips must be applied or deferred on the fast path.** The
+  geo path submits raw geometry, which clips only to a rect; rounded clips are a
+  lazy offscreen mask the fast replay bypasses. Rect clip on the fast path;
+  rounded/generic clips fall back to block-replay.
+- **Screenshots miss crashes and settle-timing.** Free-running screenshots on
+  animated/settling screens give false signals. Use render-to-quiescence +
+  virtual frame time for parity, the probe for interaction/crash coverage.
+- **The profiler `present` phase is vsync-capped by the display refresh.**
+  Profile on the target monitor before concluding a frame-rate gap.
+
+## 8. Explicit non-goals
+
+- **Dirty-region / partial present.** Upstream replays the whole scene; the win
+  is not re-recording, not redrawing less.
+- **A custom `cacheKey` API.** Superseded by the real per-node display list.
+- **Vendoring `RootNodeOwner` / the `ComposeScene` stack.** Coupled to skiko's
+  `SkiaLayer` and windowing; it fights the `:window` SDL loop. The port borrows
+  only the layer engine.
+
+## 9. Key files
+
+- `compose/ui/ui/src/nativeMain/.../RenderBackend.kt`: the interface.
+- `compose/ui/ui/src/nativeMain/.../GpuMode.kt`: renderer / driver picker.
+- `compose/ui/ui/src/skikoRendererMain/.../renderer/skia/SkiaRenderBackend.kt`.
+- `compose/ui/ui/src/sdlRendererMain/.../renderer/sdl/Sdl3RenderBackend.kt`.
+- `compose/ui/ui/src/sdlRendererMain/.../renderer/sdl/FreeTypeIcons.kt`:
+  variable-font axis rasterization.
+- `compose/ui/ui/src/commonMain/.../node/ComposeRootHost.kt`: root host,
+  hit-test, event dispatch, snapshot observer sweep.
+- `compose/ui/ui/src/commonMain/.../node/impl/ComposeOwner.kt`: the project
+  `Owner` + `GraphicsLayerOwnerLayer` bridge.
+- `compose/ui/ui/src/nativeMain/.../ui/text/SdlParagraph.native.kt`: the bridged
+  `Paragraph` (measurement, hit-test, line metrics, span painting).

ROADMAP.md

@@ -1,105 +0,0 @@
-# Renderer roadmap — fixes, performance, memory
-
-Grounded in the bubble-wrap findings (2026-07): lazy clips took the stress
-sheet from 23 → 39 FPS, but 75 Hz needs structural work; issue #2 showed that
-Cleaner-managed native memory starves when the Kotlin heap is quiet.
-
-## 1. Deterministic native-resource lifecycle
-
-Ownership closes resources the moment they're finished; GC stays as the
-safeguard, not the mechanism.
-
-- [x] **`NativeReleaseQueue`** — SDL calls are main-thread-only, so nothing may
-  destroy directly from a Cleaner or worker: release actions ENQUEUE, the main
-  loop DRAINS between frames. Cleaners become safe from any thread because
-  they only enqueue. Verified end-to-end (direct enqueue + a real
-  Cleaner→enqueue→drain cycle).
-- [x] **`SdlImageBitmap` textures** — previously never destroyed (manual SDL
-  memory, invisible to the GC nudge). A holder + Cleaner now enqueues
-  `SDL_DestroyTexture` / `SDL_DestroySurface` for the texture, render target
-  and never-realized decoded surface; explicit `close()` frees promptly.
-- [ ] **Wire `close()` into cache eviction** — the Cleaner is the current
-  release path for decoded/vector bitmaps (correct but GC-timed). Call
-  `SdlImageBitmap.close()` on image-cache eviction / `removeMemoryResource`
-  for prompt release (needs a cross-module hook — the caches hold the
-  `ImageBitmap` interface, not the concrete type).
-- [ ] **Cache-eviction closes (rest)** — every image/text cache closes what it
-  evicts (Sdl3ImageCache already does; sweep the rest, both renderers).
-- [ ] **Renderer `destroy()` chain** — window close synchronously frees every
-  pool (clip targets already do; text caches, image caches, shadow cache,
-  typefaces to follow).
-- [ ] **`SkiaImageBitmap.close()`** (surface + snapshot) + close-on-eviction in
-  the Skia caches. *Skia source sets build only on macOS/Linux — needs a mac
-  or CI leg to verify.*
-- [ ] **Demote the GC nudge** — once ownership does the work, stretch the 10s
-  interval / gate it on churn; it remains the backstop.
-
-Verification: `demo --leaktest`-style probe (cycle screens N times, print
-RSS; expect a plateau without GC sawtooth).
-
-## 2. SDL renderer performance (the 39 → 75 Hz path)
-
-- [x] **Frame profiler** — `CDN_PROFILE=1` env flag prints per-phase timings
-  (events / app pump / window pump / render / present) every ~2 s. Measure
-  first, optimize second.
-- [ ] **Dirty-region rendering** — NEXT, promoted by profiling: the app
-  re-tessellates the whole window on any invalidation. Accumulate damage from
-  invalidated layers and scissor the redraw. Biggest lever for heavy scenes.
-  Evidence (CDN_PROFILE): the full demo is DRAW-bound — draw ~34ms cold /
-  ~14ms steady, present only ~1.3ms — because it re-tessellates the whole
-  always-present sidebar (30+ text rows + icons) every rendered frame. That
-  ~14ms caps it near 70 fps; apidemo's lighter chrome fits the 6.9ms budget
-  and reaches the 144 Hz vsync ceiling. The "70 ≈ 144/2" look is coincidence,
-  NOT a vsync-half artifact — both use vsync(1). Retained layers / dirty
-  regions would stop re-tessellating the static sidebar.
-- [ ] **Retained layer textures** — cache a layer's rendered output keyed by
-  its draw content (RenderNode-style); static subtrees stop re-tessellating.
-- [ ] **Right-size clip scratch targets** (LOW — profiling showed masks aren't
-  a hot path after lazy clips): size scratch textures to the clip bbox.
-  Memory, not frame time.
-- [ ] **Glyph atlas** — text draws currently break geometry batches (z-order
-  flush per run); an atlas texture lets glyphs ride the vertex batches.
-
-## 3. Skia renderer
-
-- [ ] Bounded `SkiaImageCache` (LRU + eviction close) — unbounded HashMap today.
-- [ ] Eager-close audit of the text pipeline (mirror of the SDL sweep).
-- [ ] `saveLayer` huge-bounds clamp (GPU offscreen memory spikes — see
-  CLAUDE.md pitfall).
-
-## 4. Correctness / parity gaps (future bug reports waiting)
-
-Ordered by likelihood of a user hitting them. NOTE: this list predates several
-fixes — verify a claim against the parity heatmaps before acting (gradients and
-rotation both turned out already-working). In a parity `_diff.png`: a solid
-bright block = real gap; ghosted text = font drift.
-
-- [x] **Gradient brushes on SDL** — samplers were already implemented; the real
-  bug was UNDER-SAMPLING: fills sampled only corners, so radial/sweep on a
-  rect/round-rect rendered FLAT (a square's corners are equidistant from centre
-  → identical t). Gradient fills now grid-mesh the interior (emitRectMesh);
-  radial/sweep match upstream. (Solid fills unchanged — one quad.)
-- [x] **Layer rotation** — verified WORKING (demo GraphicsLayer "Rotation
-  (live)" + "Combined" rotate correctly); stale claim removed.
-- [ ] **Real `saveLayer` alpha on SDL** — overlapping content composites at
-  paint level; needs an offscreen (the clip-target pool can serve it).
-- [ ] **`clipPath` generic shapes** — bbox fallback clips square.
-
-## 5. Permanent tooling
-
-- [x] **Parity harness** — scripts/parity/: renders every :demo screen native +
-  JVM from the same commonMain composables, pixel-diffs, ranks by %differ,
-  emits per-screen diff heatmaps + side-by-side compares (pct in filename).
-  build/parity/ (gitignored). See scripts/parity/README.md.
-- [x] Promote the press/hover automation rig into `scripts/probe/`:
-  window-CLIENT-relative input (click/hover/hold, fractional coords, process-
-  addressed) + PrintWindow capture (works occluded). See scripts/probe/README.md.
-
-## 6. Long-term
-
-- [ ] **SDL_GPU render backend** — real stencil clipping (no masks at all),
-  pipelined batching, shader gradients. Weeks of work across three
-  platforms; items 2–4 stay useful beneath it.
-
-Suggested order: profiler → lifecycle queue + leak closes → clip-target
-right-sizing → gradients → dirty regions → the rest by demand.

TODO.md

@@ -0,0 +1,160 @@
+# TODO.md
+
+Everything the port currently leaves as a no-op, stub, hardcode, or partial
+implementation, plus the gaps worth closing before a stable 1.12 release. This
+is an audit of PROJECT code only (the `*.native.kt` / `*.sdl.kt` /
+`com.compose.sdl.*` actuals); vendored upstream under `src/vendor/` is out of
+scope.
+
+Severity is a rough guide, not a mandate:
+
+- **Blocker** for stable: a capability a typical desktop app expects that is
+  currently absent or broken.
+- **Nice-to-have**: real gap, but the app works without it.
+- **Cosmetic**: minor fidelity or edge-case behavior.
+
+Context for prioritizing: the project goal is **G1, cheap upstream-tracking**
+(see [RENDERER.md](RENDERER.md)). The **JVM Compose Desktop target is the
+documented Windows fidelity/feature tier**, so SDL-leg visual gaps (section J)
+are lower priority than the cross-cutting platform gaps (input, locale, a11y,
+cursor) that affect every backend including Skia on macOS/Linux.
+
+Renderer-internal cleanups (the deferred D2 shadow-lighting split, D3 matrix
+dedupe) live in [RENDERER.md](RENDERER.md#6-remaining-and-future-work), not
+here.
+
+---
+
+## Release-blocking shortlist for stable 1.12
+
+The cross-cutting items to weigh first (all detailed below):
+
+1. **Locale is hardcoded to `en-US`** (section E). One fix unlocks the 40+
+   vendored Material 3 translations. Cheapest high-value win in this file.
+2. **No IME / text composition** (section B). Only committed Latin text works;
+   CJK, dead keys, and accented input do not.
+3. **No cursor changes** (section D). The OS cursor never becomes an I-beam over
+   text or a hand over clickables.
+4. **No copy/paste context menu** (section C). Keyboard copy works; there is no
+   right-click or selection toolbar.
+5. **Accessibility is entirely absent** (section A). Decide whether stable
+   requires any screen-reader support at all.
+6. **Standard `Font(...)` / resource-font loading is a no-op** (section F). Only
+   pre-registered named fonts render. A blocker only if apps use the standard
+   font APIs.
+
+---
+
+## A. Accessibility (entirely absent)
+
+No accessibility bridge exists. A real `SemanticsOwner` is built but never
+surfaced to any OS accessibility API (no NSAccessibility / UIA / AT-SPI, no SDL
+a11y). Screen readers get nothing.
+
+- `compose/ui/ui/src/nativeMain/.../node/impl/ComposeOwner.kt:340` · `semanticsOwner` is instantiated but never read; no traversal into a platform a11y tree. A real a11y controller would walk the semantics tree and map roles/labels/actions to a native AT bridge. **Blocker for a11y.**
+- `compose/ui/ui/src/nativeMain/.../platform/CompositionLocals.native.kt:31` · `LocalPlatformScreenReader` default throws (`error(...)`); never provided by any window. Screen-reader-active queries are unavailable. **Blocker for a11y.**
+- `compose/ui/ui/src/nativeMain/.../node/impl/ComposeOwner.kt:297` · `accessibilityManager` implements only `calculateRecommendedTimeoutMillis` (passthrough); no announce/focus/event surface. **Nice-to-have.**
+- `compose/ui/ui/src/nativeMain/.../semantics/SemanticsRegion.native.kt:14` · `StubSemanticsRegion.intersect()`/`difference()` hardcode `false`; only `set`/`bounds` work. Region math for semantics culling is inert. **Nice-to-have.**
+
+## B. Text input / IME
+
+Committed text, arrow/backspace/enter editing, and mouse-drag selection work.
+Composition (preedit) does not.
+
+- `compose/ui/ui/src/nativeMain/.../node/impl/ComposeOwner.kt:407` · `textInputSession` awaits cancellation forever (`awaitCancellation()` at :414); no real `PlatformTextInputSession`. The modern `PlatformTextInputModifierNode` pipeline (BasicTextField2) has no IME start/stop, composition, or cursor-rect reporting. **Blocker.**
+- `compose/ui/ui/src/nativeMain/.../SDL3EventMapper.kt:126` · maps `SDL_EVENT_TEXT_INPUT` (committed) only; `SDL_EVENT_TEXT_EDITING` (preedit/composition) is never mapped, so there is no underlined composing region for dead keys / CJK. **Blocker for CJK and dead-key input.**
+- `compose/ui/ui/src/nativeMain/.../SDL3Backend.kt:111` · `SDL_StartTextInput` is called once at window init and never scoped to the focused field; `SDL_SetTextInputArea` is never called, so the IME candidate window renders at the wrong location. **Nice-to-have.**
+- `compose/ui/ui/src/commonMain/.../text/input/NoOpPlatformTextInputService.kt:24,32` · legacy `PlatformTextInputService` `startInput`/`stopInput`/`updateState` + software-keyboard toggles are all NOP. Superseded by the modern path above. **Nice-to-have / cosmetic (desktop).**
+- `compose/ui/ui/src/nativeMain/.../node/impl/ComposeOwner.kt:328` · `softwareKeyboardController.show/hide` NOP. **Cosmetic (desktop).**
+
+## C. Text toolbar and context menus (copy / paste / select-all)
+
+- `compose/ui/ui/src/nativeMain/.../node/impl/ComposeOwner.kt:311` · `textToolbar` is a stub: `showMenu`/`hide` NOP, `status` always `Hidden`. No selection or right-click copy/paste popup anywhere. Keyboard copy still works. **Blocker for text UX.**
+- `compose/foundation/.../text/selection/SelectionActuals.native.kt:42` · `addSelectionContainerTextContextMenuComponents` NOP (upstream TODO CMP-7819). No copy/select-all menu for `SelectionContainer`. **Nice-to-have.**
+- `compose/foundation/.../text/selection/TextFieldSelectionManager.native.kt:24` and `compose/foundation/.../text/input/internal/selection/TextFieldSelectionState.native.kt:36` · `addBasicTextFieldTextContextMenuComponents` NOP for both the legacy and state-based `BasicTextField`. **Nice-to-have.**
+
+## D. Pointer / cursor icons
+
+The OS cursor never changes. No SDL cursor API is called anywhere in the port.
+
+- `compose/ui/ui/src/nativeMain/.../node/impl/ComposeOwner.kt:333` · `pointerIconService.getIcon()` always returns `Default`; `setIcon()` body is empty. This is the hook `Modifier.pointerHoverIcon` drives, so hover cursor changes are swallowed. Should store the requested icon and call `SDL_SetCursor`. **Blocker for UX.**
+- `compose/ui/ui/src/nativeMain/.../input/pointer/PointerIcon.native.kt:18` · `pointerIconDefault|Crosshair|Text|Hand` are inert marker objects carrying only a name; nothing maps them to `SDL_SYSTEM_CURSOR_*`. Needs `SDL_CreateSystemCursor` + `SDL_SetCursor` (and cursor caching in the `:window` loop). **Blocker (paired with above).**
+
+## E. Locale and internationalization
+
+System-locale plumbing already exists in exactly one place:
+`components/resources/.../ResourceEnvironment.native.kt:38` reads
+`SDL_GetPreferredLocales()` for resource-qualifier resolution. Every other i18n
+consumer ignores it and hardcodes English. Wiring `Locale.current` to that same
+call is the flagship cheap win.
+
+- `compose/ui/ui/src/nativeMain/.../text/intl/Locale.native.kt:57` · `DefaultLocale` is a fixed `Locale("en-US")`, so `Locale.current` can never change. This one value keys Material 3 string translation selection, stranding the 40+ vendored `material3/internal/l10n/*.kt` tables (they are present and reachable by tag, but the key is always en-US). Fix by querying `SDL_GetPreferredLocales()` (already bound in the `sdl3` cinterop). **Blocker; fixing it transitively localizes all of Material 3.**
+- `compose/ui/ui/src/nativeMain/.../text/intl/PlatformLocale.native.kt:18` · `createPlatformLocaleDelegate().current` hardcodes `LocaleList(listOf(Locale("en-US")))`; should reflect the full ordered preferred-locale list SDL returns (the resources module currently reads only `[0]`). **Blocker.**
+- `compose/material3/.../CalendarLocale.native.kt:20` · locale-agnostic stub: `toString()` fixed `"en"`, single shared instance, `equals` treats all instances as equal. A separate type from `ui.text.intl.Locale`, so it needs its own wiring so `CalendarModel`/`PlatformDateFormat` can vary by locale. **Blocker (DatePicker/TimePicker).**
+- `compose/material3/.../internal/PlatformDateFormat.native.kt` · multiple hardcodes:
+  - `:27` `weekdayNames` hardcoded English full/short names (DatePicker shows English day initials regardless of locale). **Blocker.**
+  - `:32` `formatWithPattern`/`formatWithSkeleton` ignore the pattern/skeleton and always emit ISO `yyyy-MM-dd`. **Blocker.**
+  - `:25` `firstDayOfWeek` hardcoded `1` (Sunday); locale-dependent. **Nice-to-have.**
+  - `:44` `parse()` only accepts ISO `yyyy-MM-dd`, ignoring pattern/locale. **Nice-to-have.**
+  - `:62` `getDateInputFormat()` hardcoded `yyyy-MM-dd` / `'-'`. **Nice-to-have.**
+  - `:65` `is24HourFormat()` hardcoded `true`. **Cosmetic.**
+- `compose/ui/ui/src/nativeMain/.../text/platform/NativeStringDelegate.native.kt:17` · `toUpperCase`/`toLowerCase` use locale-independent stdlib casing; the `locale` param is ignored (wrong for Turkish dotted/dotless i, etc.). **Cosmetic.**
+- `compose/ui/ui/src/nativeMain/.../text/intl/Locale.native.kt:17` · `Locale.isRtl()` not implemented; the pipeline is LTR-only (`SdlParagraph.native.kt:333` `getBidiRunDirection` always returns `Ltr`; owners/DrawScopes default `LayoutDirection.Ltr`). No RTL shaping. **Nice-to-have.**
+- No `NumberFormat` / currency / decimal-grouping actual exists; numbers render via `toString()` with `.` decimal and no grouping regardless of locale. **Cosmetic.**
+
+**Beyond a real `getLocale`:** SDL reports language + country only (no script subtag, no calendar/clock/number preferences), and Kotlin/Native bundles no ICU. Localized month/weekday name tables, date/number/currency patterns, first-day-of-week, locale-aware casing, and RTL all still require a bundled CLDR subset or a third-party K/N i18n library. The SDL wiring is the cheap 80%; these are the expensive tail.
+
+## F. Font resolution
+
+- `compose/ui/ui/src/nativeMain/.../text/font/FontFamilyResolver.native.kt:32` · `SdlPlatformFontLoader.loadBlocking`/`awaitLoad` are NOP (return `Unit`); font bytes for `ResourceFont` / `Font(bytes)` / `LoadedFontFamily` are never loaded. Only pre-registered `NamedFont` names reach the renderer. **Blocker if the app uses standard `Font(...)` / resource-font APIs; otherwise nice-to-have.**
+- `compose/ui/ui/src/nativeMain/.../text/font/FontFamilyResolver.native.kt:38` · `PlatformFontFamilyTypefaceAdapter.resolve` returns `TypefaceResult.Immutable(Unit)`; any code reading the resolved typeface gets `Unit` (the renderer bypasses this via name lookup, so usually harmless). **Nice-to-have.**
+- `compose/ui/ui/src/commonMain/.../text/NamedFont.kt:62` · `FontFamily.projectFontName` resolves only a `FontListFontFamily` whose first font is a `NamedFont`; returns `null` for `Serif`/`SansSerif`/`Monospace`/`Cursive`/`Default`, `LoadedFontFamily`, and resource-backed families, so all of those collapse to the single default font (no serif/mono/cursive distinction). **Nice-to-have.**
+- `compose/ui/ui/src/nativeMain/.../text/font/FontFamilyResolver.native.kt:69` · deprecated `createFontFamilyResolver(fontResourceLoader)` ignores the supplied loader. **Cosmetic.**
+
+## G. Text rendering details
+
+- `compose/ui/ui/src/nativeMain/.../text/SdlParagraph.native.kt:376` · `drawNativeText` accepts and ignores text `Shadow`, stroke `DrawStyle`, and non-`SrcOver` blend, so those never render on text. **Cosmetic.**
+- `compose/foundation/.../text/StringHelpers.native.kt:31` and `compose/ui/ui/src/nativeMain/.../text/CharHelpers.native.kt:14` · `findPrecedingBreak`/`findFollowingBreak` (and `offsetByCodePoints`) do a codepoint/surrogate walk only, with no ICU grapheme clusters, so caret movement and backspace split combining marks and emoji ZWJ sequences. **Nice-to-have.**
+
+## H. Drag and drop
+
+Drop INTO the window (files + text) is fully wired and works. Drag OUT does not.
+
+- `compose/ui/ui/src/nativeMain/.../draganddrop/Sdl3DragAndDropOwner.kt:38` · `requestDragAndDropTransfer` is a NOP and `isRequestDragAndDropTransferRequired` returns `false`; `Modifier.dragAndDropSource` compiles but no OS-level drag leaves the window. Needs per-OS native work (NSDraggingSession / DoDragDrop / XDND); SDL3 has no portable start-drag. **Nice-to-have.**
+- `compose/ui/ui/src/nativeMain/.../draganddrop/Sdl3DragAndDropOwner.kt:119` · incoming transfer carries only file paths + a text blob; no image/URL/custom-MIME payloads. **Cosmetic.**
+- `compose/foundation/.../draganddrop/DragAndDropSource.native.kt:36` · no drag-shadow / drag-image feedback for internal DnD (upstream skiko renders one). **Cosmetic.**
+
+## I. Window and platform info
+
+- `compose/ui/ui/src/nativeMain/.../node/impl/ComposeOwner.kt:354` · `windowInfo.containerSize`/`containerDpSize` return `IntSize.Zero`/`DpSize.Zero`; `LocalWindowInfo.containerSize` readers (popup sizing, window-size-aware layout) get 0. **Nice-to-have.**
+- `compose/ui/ui/src/nativeMain/.../node/impl/ComposeOwner.kt:353` · `windowInfo.isWindowFocused` hardcoded `true`; not fed by SDL focus events (which the window already tracks). Focus-reactive UI will not react. **Nice-to-have.**
+- Multi-monitor: no display enumeration or per-monitor placement anywhere (`SDL_GetDisplays`/`SDL_GetDisplayBounds`/`SDL_GetDisplayForWindow` unused). **Nice-to-have.**
+- `compose/ui/ui/src/nativeMain/.../platform/PrefetchLocals.native.kt:18` · `LocalPlatformPrefetchScheduler` default is a NOP scheduler; lazy lists skip ahead-of-time item composition (correctness fine, possible scroll-in jank). **Nice-to-have (perf).**
+- `compose/ui/ui/src/nativeMain/.../node/impl/ComposeOwner.kt:324` · `autofill`/`autofillManager` are null; `requestAutofill` NOP. **Nice-to-have.**
+- `compose/ui/ui/src/nativeMain/.../node/impl/ComposeOwner.kt:279` · `hapticFeedBack.performHapticFeedback` NOP (no desktop pointer haptics API). **Cosmetic.**
+- `compose/ui/ui/src/nativeMain/.../node/impl/ComposeOwner.kt:287` · deprecated `clipboardManager` `setText`/`getText` NOP, and `clipboard.getClipEntry` null. Harmless: the real `LocalClipboard` (text + PNG image via SDL3) works. **Cosmetic.**
+- `compose/foundation/.../text/input/internal/selection/TextFieldSelectionState.native.kt:44` · `ClipboardPasteState.hasClip` aliased to `hasText`, so image-only clipboard is not detected for the paste affordance. **Cosmetic.**
+
+## J. SDL renderer graphics (Windows / `-Prenderer=sdl3` only)
+
+These affect only the SDL leg. On macOS/Linux the Skia leg implements them
+correctly, and JVM is the documented Windows fidelity tier, so these are lower
+priority under G1. Listed because SDL is the shipped Windows renderer.
+
+- `compose/ui/ui/src/sdlRendererMain/.../graphics/PathEffect.sdl.kt:15` · `dash`/`corner`/`chain`/`stamped` path effects are all NOP; dashed/dotted strokes render solid. **Nice-to-have.**
+- `compose/ui/ui/src/sdlRendererMain/.../graphics/RenderEffect.sdl.kt:16` · `RenderEffect.isSupported()` is `false`; `Modifier.blur()` and `graphicsLayer{renderEffect=...}` do nothing. `compose/ui/ui/src/sdlRendererMain/.../graphics/shadow/Blur.native.kt:33` · `Paint.setBlurFilter` NOP. **Nice-to-have (Windows visual parity).**
+- Gradients render real ramps, but `TileMode` is dropped: `t` is clamped, so `Repeated`/`Mirror`/`Decal` all behave as `Clamp` (`Sdl3DrawScope.kt:1070` samplers; `CanvasPaintActuals.native.kt:66`). **Nice-to-have.**
+- `compose/ui/ui/src/sdlRendererMain/.../graphics/CanvasPaintActuals.native.kt:106` · `ActualImageShader`/`ActualCompositeShader` are stubs; image/composite `ShaderBrush` degrades to solid fill (white/black). **Nice-to-have.**
+- `compose/ui/ui/src/sdlRendererMain/.../graphics/ColorFilter.sdl.kt:13` · tint/color-matrix/lighting color filters are empty stubs; only `BlendModeColorFilter` tint on image blits is honored (`Sdl3Canvas.kt:1251`). ColorMatrix (grayscale/saturation) and all filters on shapes are inert. **Nice-to-have.**
+- BlendMode: only `SrcOver` (plus a `Clear` special case) composites; `Multiply`/`Screen`/`Plus`/etc. are ignored (`Sdl3DrawScope.kt:206`, `Sdl3Canvas.kt:926`). Note `BlendMode.isSupported()` misleadingly returns `true`. **Nice-to-have.**
+- `compose/ui/ui/src/sdlRendererMain/.../renderer/sdl/Sdl3Canvas.kt:436` · `saveLayer` has no offscreen buffer; layer alpha is multiplied into each primitive, so overlapping content double-composites (wrong group opacity) and the layer paint's colorFilter/blendMode/renderEffect are dropped. **Nice-to-have (blocker for correct group-alpha over overlapping content).**
+- `compose/ui/ui/src/sdlRendererMain/.../renderer/sdl/Sdl3Canvas.kt:509` · `clipPath` degrades an arbitrary path to its bounding box; rotated/sheared `clipRect` collapses to an AABB. Non-rect clips leak. (Rounded/difference clips are real, with feathered AA.) **Nice-to-have.**
+- Stroke joins (`StrokeJoin`) are never applied, so polyline corners notch; `StrokeCap.Square` falls back to butt (`Sdl3DrawScope.kt:380,342`). **Nice-to-have / cosmetic.**
+- `PathFillType` (NonZero vs EvenOdd) is mostly ignored beyond a 2-contour border case; interior holes and self-intersections are not cut out, and concave fills self-overlap (`Sdl3DrawScope.kt:366,717`). **Nice-to-have.**
+- `compose/ui/ui/src/sdlRendererMain/.../renderer/sdl/Sdl3Canvas.kt:1276` · `drawPoints`/`drawRawPoints`/`drawVertices` are NOP; point-mode drawing and custom vertex meshes render nothing. **Nice-to-have.**
+- Images under a rotated layer are not rotated (`SDL_RenderTexture` is axis-aligned, `Sdl3Canvas.kt:1264`); stroked non-square ovals stroke as a circular ring (`Sdl3DrawScope.kt:527`); `SdlImageBitmap.readPixels` is a no-op (`Sdl3Offscreen.kt:117`). **Cosmetic / nice-to-have.**
+- Drop shadow is approximated (9-slice / stacked rings, not a gaussian blur; ambient vs spot largely collapsed) at `Sdl3Canvas.kt:785`; AA is a ~1px geometry fringe rather than analytic coverage. **Cosmetic.**
+
+## K. GraphicsLayer / image
+
+- `compose/ui/ui/src/sdlRendererMain/.../graphics/CanvasPaintActuals.native.kt:151` · `createImageBitmap(bytes)` throws `UnsupportedOperationException`. (`GraphicsLayer.toImageBitmap` and `snapshotBgra` do work on both renderers.) **Nice-to-have.**

TOOLING.md

@@ -0,0 +1,202 @@
+# Tooling
+
+Helper scripts and workflows used to build, vendor, and verify Compose Desktop
+Native. Each has a focused job; the deeper ones link to their own README.
+
+For architecture, source-set layout, and vendoring rules, see
+[CLAUDE.md](CLAUDE.md).
+
+## Native libraries
+
+SDL3, SDL3_ttf, SDL3_image, and FreeType are built from source as static
+libraries and linked straight into the executable. One script does it on every
+OS. Output lands in the gitignored `libs/`; versions are pinned in
+`scripts/build-sdl/build-sdl.properties`.
+
+```bash
+python3 scripts/build-sdl/build-all.py            # freetype, sdl3, sdl3-image, sdl3-ttf
+python3 scripts/build-sdl/build-all.py sdl3-ttf   # rebuild one step
+```
+
+Needs `git`, `cmake`, and Python 3 on every host (`ninja` is fetched when
+absent). Run it once per machine, or after bumping the pinned versions.
+
+## Vendoring upstream Compose
+
+Most `androidx.compose.*` code is copied byte for byte from
+`JetBrains/compose-multiplatform-core` into each module's gitignored
+`src/vendor/`. A `compose-fork.txt` manifest per module lists which upstream
+files it pulls; the pinned ref lives in `scripts/compose-fork/compose.properties`.
+
+```bash
+scripts/compose-fork/sync.sh                             # re-sync every module
+scripts/compose-fork/sync.sh compose/ui/ui/compose-fork.txt   # one module
+```
+
+Reach for this after a fresh checkout or a ref bump. Details:
+[scripts/compose-fork/README.md](scripts/compose-fork/README.md).
+
+Guardrails that keep the vendor tree honest:
+
+```bash
+python3 scripts/compose-fork/check-vendor-clean.py   # src/vendor matches the pinned refs
+python3 scripts/compose-fork/check-vendor-drift.py   # hand-edited "manual vendors" match their pin
+```
+
+`check-vendor-clean` fails if a hand-edit ever leaks into `src/vendor/`.
+`check-vendor-drift` reads the `// VENDOR-BASE:` header on every edited copy and,
+using the local upstream clone, reports whether the base actually changed since
+the pin (needs reconciling) or is merely stale (safe to re-stamp). Run both on
+every ref bump.
+
+### Coverage against upstream
+
+How much of upstream's public API the port covers is measured, not guessed.
+
+```bash
+./gradlew apiDump && python3 scripts/compose-coverage.py   # per-module coverage tables
+python3 scripts/compose-coverage.py --missing ui-text      # list uncovered declarations
+```
+
+## Verification
+
+### One-command gate
+
+`verify-mac.sh` is the runbook to run after any renderer or layout change. On
+macOS or Linux it exercises BOTH renderer legs (Skia by default, then
+`-Prenderer=sdl3`) and exits non-zero on any failure:
+
+```bash
+scripts/verify-mac.sh
+```
+
+It runs, per leg: the vendor drift and clean checks, a build of `:demo` and
+`:apidemo`, the interaction probes, the parity sweep, a memory soak, and a
+frame-time spot check. The Windows target is verified separately (see below).
+
+### Parity: native vs JVM
+
+`:demo` renders the same shared screens on two stacks: this port, and stock JVM
+Compose Desktop. `parity.py` screenshots every screen on both and pixel-diffs
+them, so a screen that diverges is a porting bug. It gates against per-screen
+golden baselines.
+
+```bash
+python3 scripts/parity/parity.py                 # all screens
+python3 scripts/parity/parity.py Buttons Shapes  # a subset
+python3 scripts/parity/parity.py --no-build      # reuse the last renders
+```
+
+How to read the diff and the percentage: [scripts/parity/README.md](scripts/parity/README.md).
+
+### Interaction probe
+
+`probe.py` launches a native window, sends window-relative input (click, hover,
+hold), and captures the client area. It packages the rigs used to reproduce
+interaction bugs. Windows-only. Details:
+[scripts/probe/README.md](scripts/probe/README.md).
+
+### Frame profiler
+
+Set `CDN_PROFILE=1` (or `CDN_PROFILE=<path>`) and run any app. Every couple of
+seconds it writes per-phase main-loop timings (events, app pump, render, with
+draw sub-phases and per-frame draw counters) to a file. `CDN_FORCERENDER=1`
+renders every frame so steady-state timings read on an otherwise idle screen.
+
+```bash
+CDN_PROFILE=1 CDN_FORCERENDER=1 ./demo/build/bin/macosArm64/debugExecutable/demo.kexe
+```
+
+Note: `present` is vsync-blocking, so profile on the target refresh rate before
+drawing conclusions about a frame-rate gap.
+
+### Demo probes
+
+`:demo` ships headless regression probes driven by CLI flags, used by the
+verify runbook and in isolation:
+
+```bash
+demo.kexe --nav3test        # Navigation 3 + ViewModel + lifecycle
+demo.kexe --backtest        # predictive-back / BackHandler
+demo.kexe --clicktest       # pointer -> upstream clickable
+demo.kexe --scrolltest      # wheel -> scrollable
+demo.kexe --multiwintest    # multi-window lifecycle
+demo.kexe --soaktest        # memory soak (CDN_SOAK_SCREEN, CDN_SOAK_STATIC, CDN_SOAK_CYCLES)
+```
+
+### Windows smoke
+
+The Mac runbook cannot cover the Windows target. Before shipping, on a Windows
+host: build the mingwX64 executables, run `scripts/probe/`, and run a publish
+dry run (only Windows compiles the full common-metadata variant table).
+
+```bat
+gradlew.bat :demo:runDebugExecutableMingwX64
+gradlew.bat :apidemo:runDebugExecutableMingwX64
+```
+
+## Consuming the port
+
+To build a third-party app against the published klibs, apply the bridge Gradle
+plugin and declare official Compose Multiplatform coordinates; the plugin swaps
+in the port's klibs on native desktop targets. Setup:
+[gradle-plugin/compose-desktop-native-bridge/README.md](gradle-plugin/compose-desktop-native-bridge/README.md).
+
+## Versioning and releasing
+
+### Version map
+
+Versions live in a few places, some of which move in lockstep. There is no
+single file to edit; know which axis you are changing.
+
+| Version | Where | Notes |
+|---------|-------|-------|
+| Project release version | The git tag `vX.Y.Z`. `PUBLISH_VERSION` (from the tag) feeds `vPublishVersion` in `build.gradle.kts`, which strips the leading `v`. Group is `com.bitsycore.compose.sdl`. | Set by the tag, not edited by hand. A non-publish build is `0.0.0-SNAPSHOT`. |
+| Vendored Compose (native side) | `COMPOSE_CORE_REF` and `COMPOSE_REF` in `scripts/compose-fork/compose.properties`, plus `compose` in `gradle/libs.versions.toml`. | Pin to a durable tag (not a `+dev` commit upstream may GC). Re-sync after changing. |
+| JVM parity forcing | `vComposeJvmVersion` in `demo`, `apidemo`, and `material-symbols` `build.gradle.kts`. | Must be a version PUBLISHED to Maven Central. It may lag the vendored native ref (a documented skew) until the matching version is published. |
+| Skiko | `skiko` in `gradle/libs.versions.toml`. | Must expose the `org.jetbrains.skiko.node` `RenderNode` / `GraphicsContext` API the vendored compose-core uses. Verify with a throwaway `skikoRendererMain` compile if unsure. |
+| SDL3 / SDL3_ttf / SDL3_image / FreeType | `scripts/build-sdl/build-sdl.properties`. | Rebuild `libs/` with `build-all.py` after any change. |
+| Bridge substituted version | Defaults to the bridge plugin's own published version; consumers override with the `composeDesktopNative.version` Gradle property. | The plugin publishes with the release tag, so a consumer on the matching plugin version resolves the right klibs automatically. |
+
+### Bump the upstream Compose ref
+
+Run this on each upstream bump; it is the flow that keeps the sync tax low.
+
+1. Edit `COMPOSE_CORE_REF` / `COMPOSE_REF` in `compose.properties` (and `compose`
+   in `libs.versions.toml` if the coordinate version moved).
+2. `scripts/compose-fork/sync.sh`
+3. `python3 scripts/compose-fork/check-vendor-drift.py`. For any manual vendor
+   whose upstream base actually changed, reconcile by hand; otherwise re-stamp
+   its `// VENDOR-BASE:` header to the new ref.
+4. Build both legs and fix any fallout.
+5. `scripts/verify-mac.sh` (both legs green, including the soak and parity gates).
+6. If a matching Compose version is now published to Maven, bump
+   `vComposeJvmVersion` in demo/apidemo/material-symbols to close the skew.
+7. Run WIN-SMOKE on a Windows host.
+8. Re-seed parity baselines only if metrics legitimately moved
+   (`parity.py --update-baselines`), and record why.
+
+### Cut a release
+
+1. Complete the ref-bump flow above and confirm it is green. For a STABLE
+   release, `vComposeJvmVersion` should match the vendored ref (no skew).
+2. On a Windows host, run `gradlew :window:compileCommonMainKotlinMetadata`.
+   Only Windows compiles the full common-metadata variant table, and the root
+   KotlinMultiplatform publications live there; a macOS-only publish leaves the
+   roots without mingwX64 variants (this bit v0.1.15).
+3. `git tag vX.Y.Z && git push origin vX.Y.Z`. This triggers `.github/workflows/publish.yml`.
+
+What the publish job does, so you can read a failure:
+
+- Each host publishes only its own target's publications to GitHub Packages
+  under `com.bitsycore.compose.sdl:*`. Windows additionally publishes the root
+  KotlinMultiplatform metadata, the `jvm` publication, and the bridge plugin
+  (only Windows declares every target).
+- The `MODULES` list in the workflow must stay in sync with the modules in
+  `settings.gradle.kts`.
+- A partial publish (for example a dropped connection mid-upload) deletes this
+  host's half-published versions for the tag and retries, so a rerun is safe.
+- The demo and apidemo release binaries are zipped and attached to the GitHub
+  Release for the tag.
+
+4. Verify a consumer build against the new version resolves through the bridge.

apidemo/build.gradle.kts

@@ -20,8 +20,8 @@ val vHostSupportsMingw: Boolean by rootProject.extra
 // COMPOSE_CORE_REF (see scripts/compose-fork/compose.properties); mirrors
 // :demo's forcing (Gradle orders "+dev" BELOW the plain version, so the
 // plugin's beta01 would win conflict resolution without it).
-val vComposeJvmVersion = "1.12.0-beta01+dev4324"
-val vComposeM3JvmVersion = "1.12.0-alpha03+dev4324"
+val vComposeJvmVersion = libs.versions.compose.get()
+val vComposeM3JvmVersion = libs.versions.composeMaterial3.get()
 val vComposeJvmForced = mapOf(
     "org.jetbrains.compose.runtime" to vComposeJvmVersion,
     "org.jetbrains.compose.ui" to vComposeJvmVersion,
@@ -106,7 +106,7 @@ kotlin {
                 // invisible to the granular-metadata visibility check. The
                 // runtime is the official klib everywhere, never substituted
                 // (jvm configs force the +dev build above).
-                implementation("org.jetbrains.compose.runtime:runtime:1.11.1")
+                implementation("org.jetbrains.compose.runtime:runtime:${libs.versions.composeRuntime.get()}")
                 implementation("org.jetbrains.compose.ui:ui:$vComposeJvmVersion")
                 implementation("org.jetbrains.compose.ui:ui-graphics:$vComposeJvmVersion")
                 implementation("org.jetbrains.compose.ui:ui-text:$vComposeJvmVersion")

components/resources/library/src/nativeMain/kotlin/org/jetbrains/compose/resources/vector/xmldom/DomXmlParser.kt

@@ -16,6 +16,8 @@ package org.jetbrains.compose.resources.vector.xmldom
    CDATA skipping, and the five predefined entities plus numeric character
    references. No DTD expansion, no processing-instruction handling beyond
    skipping — malformed input throws MalformedXMLException like upstream. */
+// VENDOR-BASE(COMPOSE_REF): components/resources/library/src/nativeMain/kotlin/org/jetbrains/compose/resources/vector/xmldom/DomXmlParser.kt @ v1.12.0-beta03+dev4483
+// (fresh REIMPL, not a copy-edit — the base ref marks the upstream API it tracks)
 
 internal fun parse(xml: String): Element {
 	val vParser = XmlDomParser(xml)

compose/foundation/foundation/src/commonMain/kotlin/androidx/compose/foundation/text/selection/SelectionLayout.kt

@@ -18,6 +18,7 @@
 
 // MANUAL VENDOR of upstream compose/foundation/foundation/src/commonMain/kotlin/
 // androidx/compose/foundation/text/selection/SelectionLayout.kt.
+// VENDOR-BASE: compose/foundation/foundation/src/commonMain/kotlin/androidx/compose/foundation/text/selection/SelectionLayout.kt @ v1.12.0-beta03+dev4483
 //
 // Change vs upstream: MultiSelectionLayout.crossStatus and slotToIndex clamp their
 // infoList index to the valid range. Upstream assumes that if the drag position never

compose/sdl/window/src/nativeMain/kotlin/com/compose/sdl/ComposeWindow.kt

@@ -38,6 +38,7 @@ import sdl3.SDL_Delay
 import sdl3.SDL_GetPerformanceCounter
 import sdl3.SDL_GetPerformanceFrequency
 import sdl3.SDL_GetTicks
+import sdl3.SDL_GetTicksNS
 import sdl3.SDL_Quit
 import sdl3.SDL_SetWindowTitle
 import sdl3.SDL_WaitEventTimeout
@@ -144,7 +145,7 @@ fun nativeComposeApp(content: @Composable ApplicationScope.() -> Unit) {
 
 		appComposition.setContent { appScope.content() }
 		// Compose the initial Window() declarations before entering the loop.
-		appClock.sendFrame()
+		appClock.sendFrame(frameClockNanos())
 		yield()
 
 		// ============
@@ -153,6 +154,9 @@ fun nativeComposeApp(content: @Composable ApplicationScope.() -> Unit) {
 		var vRenderedSinceGc = false
 		while (!runtime.exitRequested) {
 			FrameProfiler.mark()
+			// One virtual 16.6ms tick per loop iteration (no-op unless useVirtualFrameTime) —
+			// all windows' clocks share the same timestamp this iteration.
+			advanceVirtualFrame()
 			Snapshot.sendApplyNotifications()
 
 			// ============
@@ -185,7 +189,7 @@ fun nativeComposeApp(content: @Composable ApplicationScope.() -> Unit) {
 			// ============
 			//  App composition pump — Window()s may appear / disappear here.
 			Snapshot.sendApplyNotifications()
-			appClock.sendFrame()
+			appClock.sendFrame(frameClockNanos())
 			yield()
 			runtime.reapDestroyed()
 
@@ -209,10 +213,10 @@ fun nativeComposeApp(content: @Composable ApplicationScope.() -> Unit) {
 			val vAppPending = appRecomposer.hasPendingWork
 			for (vW in runtime.windows.toList()) {
 				vW.installGlobals()
-				vW.host.sendAnimationFrame(SDL_GetTicks().toLong() * 1_000_000L)
+				vW.host.sendAnimationFrame(animationClockNanos())
 				mainDispatcher.drainPending()
 				Snapshot.sendApplyNotifications()
-				vW.frameClock.sendFrame()
+				vW.frameClock.sendFrame(frameClockNanos())
 				yield()
 				FrameProfiler.phase("pump")
 				if (vW.shouldRender()) {
@@ -352,6 +356,57 @@ internal object FrameProfiler {
    their native memory (see the main loop's native-memory nudge). */
 private val kForceRender: Boolean = platform.posix.getenv("CDN_FORCERENDER") != null
 
+// ==================
+// MARK: Probe / screenshot support (render-to-quiescence)
+// ==================
+
+/* Set BEFORE nativeComposeApp/nativeComposeWindow: every window's composition then runs
+   under an InfiniteAnimationPolicy that CANCELS infinite animations, so
+   rememberInfiniteTransition & co. freeze at their initial value — the same mechanism
+   upstream's test rules use. Screenshot/parity runs enable it so looping screens can
+   reach quiescence and capture deterministically. */
+var disableInfiniteAnimations: Boolean = false
+
+/* The cancelling policy: a coroutine that ends in CancellationException counts as
+   cancelled (not failed), so only the animation coroutine stops — nothing propagates. */
+private object CancelInfiniteAnimationsPolicy : androidx.compose.ui.platform.InfiniteAnimationPolicy {
+	override suspend fun <R> onInfiniteOperation(block: suspend () -> R): R =
+		throw CancellationException("infinite animations are disabled (disableInfiniteAnimations)")
+}
+
+/* Set BEFORE nativeComposeApp/nativeComposeWindow: the composition + animation frame
+   clocks advance a VIRTUAL 16.6ms per main-loop iteration instead of reading SDL's
+   real-time ticks — the native mirror of the JVM parity leg's render(nanos) stepping.
+   Animations then progress by exact per-frame deltas, so anything time-raced (e.g. a
+   bring-into-view scroll interrupted mid-flight) resolves identically on every run and
+   screenshots become deterministic. Input timestamps and FPS stay on real time. */
+var useVirtualFrameTime: Boolean = false
+
+private var virtualFrameNanos = 0L
+
+private fun advanceVirtualFrame() {
+	if (useVirtualFrameTime) virtualFrameNanos += 16_666_667L
+}
+
+// Timestamp for the composition frame clocks (recomposer + withFrameNanos animations).
+private fun frameClockNanos(): Long =
+	if (useVirtualFrameTime) virtualFrameNanos else SDL_GetTicksNS().toLong()
+
+// Timestamp for the owner's node-animation clock — real path keeps the pre-existing
+// ms-resolution SDL_GetTicks base so non-screenshot behaviour is bit-for-bit unchanged.
+private fun animationClockNanos(): Long =
+	if (useVirtualFrameTime) virtualFrameNanos else SDL_GetTicks().toLong() * 1_000_000L
+
+// The window currently inside renderFrame — the loop is single-threaded, so a plain
+// var is enough for onFrame probes to address "the window I'm being called for".
+private var renderingWindow: WindowInstance? = null
+
+/* From inside an onFrame callback: true while the just-rendered window still has pending
+   work (recomposition, layout/draw invalidation, or an animation awaiting the next frame).
+   Screenshot probes capture once this stays false for a few consecutive frames instead of
+   at a fixed frame count. Outside onFrame it answers false. */
+fun windowHasInvalidations(): Boolean = renderingWindow?.hasInvalidations() ?: false
+
 @OptIn(kotlin.native.runtime.NativeRuntimeApi::class)
 private fun collectNativeGarbage() = kotlin.native.runtime.GC.collect()
 
@@ -490,8 +545,9 @@ internal class WindowInstance(
 	private var hasMousePos = false
 
 	private var frameIndex = 0
-	private var fpsFrames = 0
-	private var fpsLastMs = SDL_GetTicks()
+	private var fpsEma = 0.0
+	private var fpsLastFrameMs = SDL_GetTicks()
+	private var fpsLastTitleMs = 0uL
 
 	// Escape → back (upstream desktop's BackNavigationEventInput): unconsumed
 	// Escape completes a back navigation on THIS window's dispatcher.
@@ -545,6 +601,10 @@ internal class WindowInstance(
 
 		host = ComposeRootHost(inDensity = backend.pixelDensity)
 		host.attach()
+		// A layer whose content changed (OwnedLayer.invalidate) schedules a frame
+		// even when nothing else (recompose / relayout) is pending — retained layers
+		// need this so a draw-only state change still repaints.
+		host.setInvalidationCallback { needsFrame = true }
 		facade = ComposeNativeWindow(backend, gpuMode, initialTitle)
 		navigationEventOwner.navigationEventDispatcher.addInput(backNavigationInput)
 
@@ -553,7 +613,11 @@ internal class WindowInstance(
 		// setContent below).
 		installGlobals()
 
-		val vRecomposer = Recomposer(inScope.coroutineContext + frameClock)
+		// Effect context for this window's composition — the screenshot flag injects the
+		// infinite-animation-cancelling policy (see disableInfiniteAnimations above).
+		var vEffectContext = inScope.coroutineContext + frameClock
+		if (disableInfiniteAnimations) vEffectContext += CancelInfiniteAnimationsPolicy
+		val vRecomposer = Recomposer(vEffectContext)
 		recomposer = vRecomposer
 		recomposeJob = inScope.launch(frameClock) { vRecomposer.runRecomposeAndApplyChanges() }
 		val vComposition = Composition(host.applier, vRecomposer)
@@ -754,6 +818,14 @@ internal class WindowInstance(
 	fun shouldRender(): Boolean =
 		needsFrame || (recomposer?.hasPendingWork == true) || onFrame != null || kForceRender
 
+	/* True while this window still has pending work: a state/layout/draw invalidation
+	   (needsFrame), recomposer work, or a composition/node animation awaiting the next
+	   frame. Sampled by windowHasInvalidations() from onFrame probes — the quiescence
+	   signal for render-to-settle screenshot capture. */
+	fun hasInvalidations(): Boolean =
+		needsFrame || recomposer?.hasPendingWork == true ||
+			frameClock.hasAwaiters || host.hasAnimationAwaiters()
+
 	// TEMP measurement: CDN_FORCERENDER=1 forces every frame to render so
 	// sustained steady-state timings can be measured on otherwise-idle screens.
 
@@ -774,32 +846,48 @@ internal class WindowInstance(
 		}
 
 		vRender.beginFrame(1f)
-		vRender.drawRoot(host)
-		if (onFrame != null && !onFrame.invoke(vRender, frameIndex)) {
+		vRender.drawRoot { canvas -> host.drawRoot(canvas) }
+		if (onFrame != null) {
+			renderingWindow = this
+			val vContinue = onFrame.invoke(vRender, frameIndex)
+			renderingWindow = null
 			// Probe consumers end the app when their scenario completes.
-			facade.close()
+			if (!vContinue) facade.close()
 		}
 		FrameProfiler.phase("  draw")
 		vRender.endFrame()
 		FrameProfiler.phase("  present")
 		frameIndex++
 
-		// FPS — refreshed ~once a second, per window.
-		fpsFrames++
+		// FPS — instantaneous inter-frame rate, EMA-smoothed, title refreshed
+		// ~4x/sec. This shows within ~2 rendered frames of ANY activity rather
+		// than waiting for a full second of unbroken rendering to accumulate
+		// (the old fixed-window counter never got its first update: bursty
+		// interaction kept idling before 1s elapsed, and the idle-skip reset the
+		// window each time — so FPS only appeared during a long enough page
+		// transition). A dt outside 1..100ms is the first frame or a resume from
+		// idle (the gap isn't a real frame interval), so it's not sampled — the
+		// title just holds the last active rate while idle.
 		val vNowMs = SDL_GetTicks()
-		val vElapsed = (vNowMs - fpsLastMs).toInt()
-		if (vElapsed >= 1000) {
-			val vFps = fpsFrames * 1000 / vElapsed
-			facade.updateFps(vFps)
-			SDL_SetWindowTitle(backend.window?.reinterpret(), "${facade.title} · $vFps FPS")
-			fpsFrames = 0
-			fpsLastMs = vNowMs
+		val vDt = (vNowMs - fpsLastFrameMs).toInt()
+		fpsLastFrameMs = vNowMs
+		if (vDt in 1..100) {
+			val vInst = 1000.0 / vDt
+			fpsEma = if (fpsEma <= 0.0) vInst else fpsEma * 0.9 + vInst * 0.1
+			if ((vNowMs - fpsLastTitleMs).toInt() >= 250) {
+				val vFps = (fpsEma + 0.5).toInt()
+				facade.updateFps(vFps)
+				SDL_SetWindowTitle(backend.window?.reinterpret(), "${facade.title} · $vFps FPS")
+				fpsLastTitleMs = vNowMs
+			}
 		}
 	}
 
+	// Idle-skip calls this: drop the frame timer so the resume-from-idle frame's
+	// dt (the whole idle gap) isn't sampled as a real interval. The EMA is left
+	// intact so the title keeps showing the last active rate while idle.
 	fun resetFpsWindow() {
-		fpsFrames = 0
-		fpsLastMs = SDL_GetTicks()
+		fpsLastFrameMs = SDL_GetTicks()
 	}
 
 	fun destroy() {

compose/sdl/window/src/nativeMain/kotlin/com/compose/sdl/SDL3FrameClock.kt

@@ -26,7 +26,12 @@ internal class SDL3FrameClock : MonotonicFrameClock {
 	override suspend fun <R> withFrameNanos(onFrame: (Long) -> R): R =
 		broadcast.withFrameNanos(onFrame)
 
-	fun sendFrame() {
-		broadcast.sendFrame(SDL_GetTicksNS().toLong())
+	fun sendFrame(inNanos: Long = SDL_GetTicksNS().toLong()) {
+		broadcast.sendFrame(inNanos)
 	}
+
+	// Coroutines (recomposer / composition animations) currently suspended in withFrameNanos
+	// awaiting the next sendFrame — the "an animation is still running" half of the window's
+	// quiescence signal (see WindowInstance.hasInvalidations).
+	val hasAwaiters: Boolean get() = broadcast.hasAwaiters
 }

compose/ui/ui-backhandler/build.gradle.kts

@@ -13,7 +13,7 @@ kotlin {
 	sourceSets {
 		commonMain {
 			dependencies {
-				api("org.jetbrains.compose.runtime:runtime:1.11.1")
+				api("org.jetbrains.compose.runtime:runtime:${libs.versions.composeRuntime.get()}")
 				api("androidx.navigationevent:navigationevent-compose:1.1.2")
 				api(project(":ui-util"))
 				implementation(libs.kotlinx.coroutines.core)

compose/ui/ui-geometry/build.gradle.kts

@@ -13,7 +13,7 @@ kotlin {
 	sourceSets {
 		commonMain {
 			dependencies {
-				api("org.jetbrains.compose.runtime:runtime:1.11.1")
+				api("org.jetbrains.compose.runtime:runtime:${libs.versions.composeRuntime.get()}")
 				api(project(":ui-util"))
 			}
 			kotlin.srcDir("src/vendor/common/kotlin")

compose/ui/ui-tooling-preview/build.gradle.kts

@@ -20,7 +20,7 @@ kotlin {
 	sourceSets {
 		commonMain {
 			dependencies {
-				api("org.jetbrains.compose.runtime:runtime:1.11.1")
+				api("org.jetbrains.compose.runtime:runtime:${libs.versions.composeRuntime.get()}")
 			}
 			kotlin.srcDir("src/vendor/common/kotlin")
 		}

compose/ui/ui-unit/build.gradle.kts

@@ -13,7 +13,7 @@ kotlin {
 	sourceSets {
 		commonMain {
 			dependencies {
-				api("org.jetbrains.compose.runtime:runtime:1.11.1")
+				api("org.jetbrains.compose.runtime:runtime:${libs.versions.composeRuntime.get()}")
 				api(project(":ui-geometry"))
 				api(project(":ui-util"))
 			}

compose/ui/ui-util/build.gradle.kts

@@ -15,7 +15,7 @@ kotlin {
 	sourceSets {
 		commonMain {
 			dependencies {
-				api("org.jetbrains.compose.runtime:runtime:1.11.1")
+				api("org.jetbrains.compose.runtime:runtime:${libs.versions.composeRuntime.get()}")
 				api("androidx.collection:collection:1.5.0")
 			}
 			kotlin.srcDir("src/vendor/common/kotlin")

compose/ui/ui/build.gradle.kts

@@ -156,9 +156,9 @@ kotlin {
                 api(project(":ui-geometry"))
                 api(project(":ui-unit"))
                 api(project(":ui-backhandler"))
-                api("org.jetbrains.compose.runtime:runtime:1.11.1")
-                api("org.jetbrains.compose.runtime:runtime-saveable:1.11.1")
-                api("androidx.compose.runtime:runtime-retain:1.11.1")
+                api("org.jetbrains.compose.runtime:runtime:${libs.versions.composeRuntime.get()}")
+                api("org.jetbrains.compose.runtime:runtime-saveable:${libs.versions.composeRuntime.get()}")
+                api("androidx.compose.runtime:runtime-retain:${libs.versions.composeRuntime.get()}")
                 api("androidx.navigationevent:navigationevent-compose:1.1.2")
                 api("androidx.savedstate:savedstate:1.5.0")
                 api("androidx.savedstate:savedstate-compose:1.5.0")

compose/ui/ui/compose-fork.txt

@@ -514,14 +514,14 @@ skikoMain/kotlin/ -> src/vendor/skikoRenderer/kotlin/
 #     | skikoMain/kotlin/androidx/compose/ui/graphics/SkiaVertexMode.skiko.kt -> src/vendor/skikoRenderer/kotlin/androidx/compose/ui/graphics/SkiaVertexMode.skiko.kt
 #     | skikoMain/kotlin/androidx/compose/ui/graphics/layer/SkiaGraphicsLayer.skiko.kt -> src/vendor/skikoRenderer/kotlin/androidx/compose/ui/graphics/layer/SkiaGraphicsLayer.skiko.kt
 #     | skikoMain/kotlin/androidx/compose/ui/graphics/shadow/Blur.skiko.kt -> src/vendor/skikoRenderer/kotlin/androidx/compose/ui/graphics/shadow/Blur.skiko.kt
-!skikoMain/kotlin/androidx/compose/ui/graphics/ImageBitmap.skiko.kt
+# B6.1 (2026-07-16): un-refused — skiko leg adopts upstream graphics actuals.
+# SkiaBackedCanvas is then MANUAL-VENDORED (moved to src/skikoRendererMain, re-refused
+# below) to also implement the port Native* draw contracts. See RENDERER_TASKS.md B6.1.
+# B6.2: un-refused — skiko leg adopts upstream GraphicsLayer/GraphicsContext (real
+# skiko RenderNode) now the canvas is SkiaBackedCanvas. See RENDERER_TASKS.md B6.2.
 !skikoMain/kotlin/androidx/compose/ui/graphics/SkiaBackedCanvas.skiko.kt
-!skikoMain/kotlin/androidx/compose/ui/graphics/SkiaBackedPaint.skiko.kt
-!skikoMain/kotlin/androidx/compose/ui/graphics/SkiaGraphicsContext.skiko.kt
+# B6.1: MANUAL-VENDORED (flattened toBitmap/putBytesInto expect-actuals — see the file).
 !skikoMain/kotlin/androidx/compose/ui/graphics/SkiaImageAsset.skiko.kt
-!skikoMain/kotlin/androidx/compose/ui/graphics/SkiaShader.skiko.kt
-!skikoMain/kotlin/androidx/compose/ui/graphics/layer/SkiaGraphicsLayer.skiko.kt
-!skikoMain/kotlin/androidx/compose/ui/graphics/shadow/Blur.skiko.kt
 
 SET_FOLDER=compose/ui/ui-text/src
 
@@ -757,11 +757,13 @@ skikoMain/kotlin/androidx/compose/ui/text/style/TextMotion.skiko.kt -> src/vendo
 #     | androidMain/kotlin/androidx/compose/ui/window/AndroidDialog.android.kt -> src/vendor/android/kotlin/androidx/compose/ui/window/AndroidDialog.android.kt
 #     | androidMain/kotlin/androidx/compose/ui/window/AndroidPopup.android.kt -> src/vendor/android/kotlin/androidx/compose/ui/window/AndroidPopup.android.kt
 #     | androidMain/kotlin/androidx/compose/ui/window/SecureFlagPolicy.android.kt -> src/vendor/android/kotlin/androidx/compose/ui/window/SecureFlagPolicy.android.kt
-#   desktopMain (173)
+#   desktopMain (175)
 #     | desktopMain/kotlin/androidx/compose/ui/Actuals.desktop.kt -> src/vendor/desktop/kotlin/androidx/compose/ui/Actuals.desktop.kt
 #     | desktopMain/kotlin/androidx/compose/ui/ComposeDesktopEntryPoint.kt -> src/vendor/desktop/kotlin/androidx/compose/ui/ComposeDesktopEntryPoint.kt
 #     | desktopMain/kotlin/androidx/compose/ui/ComposeFeatureFlags.desktop.kt -> src/vendor/desktop/kotlin/androidx/compose/ui/ComposeFeatureFlags.desktop.kt
 #     | desktopMain/kotlin/androidx/compose/ui/ConfigureSwingGlobalsForCompose.desktop.kt -> src/vendor/desktop/kotlin/androidx/compose/ui/ConfigureSwingGlobalsForCompose.desktop.kt
+#     | desktopMain/kotlin/androidx/compose/ui/DesktopComposeUiFlags.skiko.kt -> src/vendor/desktop/kotlin/androidx/compose/ui/DesktopComposeUiFlags.skiko.kt
+#     | desktopMain/kotlin/androidx/compose/ui/ProvideSystemTheme.desktop.kt -> src/vendor/desktop/kotlin/androidx/compose/ui/ProvideSystemTheme.desktop.kt
 #     | desktopMain/kotlin/androidx/compose/ui/awt/AwtDimension.desktop.kt -> src/vendor/desktop/kotlin/androidx/compose/ui/awt/AwtDimension.desktop.kt
 #     | desktopMain/kotlin/androidx/compose/ui/awt/AwtEventFilter.desktop.kt -> src/vendor/desktop/kotlin/androidx/compose/ui/awt/AwtEventFilter.desktop.kt
 #     | desktopMain/kotlin/androidx/compose/ui/awt/AwtEvents.desktop.kt -> src/vendor/desktop/kotlin/androidx/compose/ui/awt/AwtEvents.desktop.kt
@@ -1092,7 +1094,7 @@ skikoMain/kotlin/androidx/compose/ui/text/style/TextMotion.skiko.kt -> src/vendo
 #     | wasmJsMain/kotlin/androidx/compose/ui/Actuals.wasm.kt -> src/vendor/wasmJs/kotlin/androidx/compose/ui/Actuals.wasm.kt
 #     | wasmJsMain/kotlin/androidx/compose/ui/internal/System.wasm.kt -> src/vendor/wasmJs/kotlin/androidx/compose/ui/internal/System.wasm.kt
 #     | wasmJsMain/kotlin/androidx/compose/ui/platform/PlatformClipboard.wasm.kt -> src/vendor/wasmJs/kotlin/androidx/compose/ui/platform/PlatformClipboard.wasm.kt
-#   webMain (39)
+#   webMain (40)
 #     | webMain/kotlin/androidx/compose/ui/dom/Events.web.kt -> src/vendor/web/kotlin/androidx/compose/ui/dom/Events.web.kt
 #     | webMain/kotlin/androidx/compose/ui/draganddrop/DragAndDrop.web.kt -> src/vendor/web/kotlin/androidx/compose/ui/draganddrop/DragAndDrop.web.kt
 #     | webMain/kotlin/androidx/compose/ui/draganddrop/DragAndDropTransferData.web.kt -> src/vendor/web/kotlin/androidx/compose/ui/draganddrop/DragAndDropTransferData.web.kt
@@ -1129,6 +1131,7 @@ skikoMain/kotlin/androidx/compose/ui/text/style/TextMotion.skiko.kt -> src/vendo
 #     | webMain/kotlin/androidx/compose/ui/window/ComposeViewportConfiguration.web.kt -> src/vendor/web/kotlin/androidx/compose/ui/window/ComposeViewportConfiguration.web.kt
 #     | webMain/kotlin/androidx/compose/ui/window/ComposeWindow.web.kt -> src/vendor/web/kotlin/androidx/compose/ui/window/ComposeWindow.web.kt
 #     | webMain/kotlin/androidx/compose/ui/window/ComposeWindowInternal.web.kt -> src/vendor/web/kotlin/androidx/compose/ui/window/ComposeWindowInternal.web.kt
+#     | webMain/kotlin/androidx/compose/ui/window/RootScrollObserver.kt -> src/vendor/web/kotlin/androidx/compose/ui/window/RootScrollObserver.kt
 #     | webMain/kotlin/androidx/compose/ui/window/SystemThemeObserver.web.kt -> src/vendor/web/kotlin/androidx/compose/ui/window/SystemThemeObserver.web.kt
 #     | webMain/kotlin/androidx/compose/ui/window/WebCompositionLocals.kt -> src/vendor/web/kotlin/androidx/compose/ui/window/WebCompositionLocals.kt
 #     | webMain/kotlin/androidx/compose/ui/window/WebTextInputSession.kt -> src/vendor/web/kotlin/androidx/compose/ui/window/WebTextInputSession.kt

compose/ui/ui/src/commonMain/kotlin/androidx/compose/ui/platform/Synchronization.kt

@@ -10,6 +10,7 @@
  * Line-for-line kept in sync; the entry in compose/ui/compose-fork.txt is
  * commented out so this file survives `scripts/compose-fork/sync.sh`.
  */
+// VENDOR-BASE: compose/ui/ui/src/commonMain/kotlin/androidx/compose/ui/platform/Synchronization.kt @ v1.12.0-beta03+dev4483
 
 package androidx.compose.ui.platform
 

compose/ui/ui/src/commonMain/kotlin/androidx/compose/ui/text/platform/Synchronization.kt

@@ -6,6 +6,7 @@
  * compose/ui/compose-fork.txt is commented out so this file survives
  * `scripts/compose-fork/sync.sh`.
  */
+// VENDOR-BASE: compose/ui/ui-text/src/commonMain/kotlin/androidx/compose/ui/text/platform/Synchronization.kt @ v1.12.0-beta03+dev4483
 
 package androidx.compose.ui.text.platform
 

compose/ui/ui/src/commonMain/kotlin/com/compose/sdl/graphics/GraphicsLayerFactory.kt

@@ -1,17 +0,0 @@
-package com.compose.sdl.graphics
-
-import androidx.compose.ui.graphics.layer.GraphicsLayer
-
-// ==================
-// MARK: GraphicsLayer factory (project bridge)
-// ==================
-
-/* The vendored `expect class GraphicsLayer` exposes neither a constructor nor
-   the isReleased setter to common code — upstream owners create layers from
-   platform source sets. ComposeOwner lives in commonMain, so these two hops
-   let its GraphicsContext create and release the project record/replay
-   actual (GraphicsLayer.native.kt). */
-
-internal expect fun createProjectGraphicsLayer(): GraphicsLayer
-
-internal expect fun releaseProjectGraphicsLayer(inLayer: GraphicsLayer)

compose/ui/ui/src/commonMain/kotlin/com/compose/sdl/graphics/NativeFinishableCanvas.kt

@@ -0,0 +1,17 @@
+package com.compose.sdl.graphics
+
+// ==================
+// MARK: NativeFinishableCanvas
+// ==================
+
+/*
+ A renderer canvas that must be flushed once drawing into it is done — SDL batches
+ geometry and only submits on flush; an offscreen SDL canvas must flush before its
+ backing texture is read. Implemented by Sdl3Canvas (real flush) and SkiaCanvas
+ (no-op — Skia save/restore is balanced per call). Lets renderer-agnostic code
+ (e.g. GraphicsLayer.toImageBitmap) commit an offscreen render without knowing the
+ concrete canvas type.
+*/
+interface NativeFinishableCanvas {
+	fun finish()
+}

compose/ui/ui/src/commonMain/kotlin/com/compose/sdl/text/TextDrawModifier.kt

@@ -44,6 +44,14 @@ interface NativeTextCanvas {
 		// (underline / line-through). Per-run overrides ride in via inSpans.
 		inBaseItalic: Boolean = false,
 		inTextDecoration: TextDecoration? = null,
+		// The paragraph's per-line band height in px (TextStyle.lineHeight when the
+		// style specifies one — SdlParagraph passes it so glyph rows stack exactly
+		// where layout put the line boxes). <= 0 → derive from font metrics (legacy
+		// behaviour; icon callers and TextDrawNode don't pass it).
+		inLineHeightPx: Float = 0f,
+		// Compat-trim (raw styles): the FIRST line keeps the tight font cell. False
+		// for M3's LineHeightStyle(Trim.None) — every line is the full band.
+		inTrimFirstLine: Boolean = true,
 	)
 }
 

compose/ui/ui/src/nativeMain/kotlin/androidx/compose/ui/graphics/layer/GraphicsLayer.native.kt

@@ -1,161 +0,0 @@
-package androidx.compose.ui.graphics.layer
-
-import androidx.compose.ui.geometry.Offset
-import androidx.compose.ui.geometry.Size
-import androidx.compose.ui.graphics.BlendMode
-import androidx.compose.ui.graphics.Canvas
-import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.graphics.ColorFilter
-import androidx.compose.ui.graphics.ImageBitmap
-import androidx.compose.ui.graphics.Outline
-import androidx.compose.ui.graphics.Path
-import androidx.compose.ui.graphics.RectangleShape
-import androidx.compose.ui.graphics.RenderEffect
-import androidx.compose.ui.graphics.drawscope.DrawScope
-import androidx.compose.ui.unit.Density
-import androidx.compose.ui.unit.IntOffset
-import androidx.compose.ui.unit.IntSize
-import androidx.compose.ui.unit.LayoutDirection
-
-// ==================
-// MARK: GraphicsLayer — native no-op actual
-// ==================
-//
-// Upstream's skiko actual (SkiaGraphicsLayer.skiko.kt, 513L) uses Skia's
-// Picture/Canvas API for record + replay. We don't have skiko on the
-// SDL3 path and the Skia path doesn't route through GraphicsLayer yet
-// — the renderer's per-node draw does its own composition. So this
-// actual is a plain field bag with no rendering behavior: setters store
-// their values, getters return them, record/draw/toImageBitmap are
-// no-ops. Nothing in our pipeline constructs a GraphicsLayer yet.
-
-@Suppress("PropertyName", "unused")
-actual class GraphicsLayer {
-
-	actual var compositingStrategy: CompositingStrategy = CompositingStrategy.Auto
-	actual var topLeft: IntOffset = IntOffset.Zero
-	actual var size: IntSize = IntSize.Zero
-	actual var pivotOffset: Offset = Offset.Unspecified
-	actual var alpha: Float = 1f
-	actual var scaleX: Float = 1f
-	actual var scaleY: Float = 1f
-	actual var translationX: Float = 0f
-	actual var translationY: Float = 0f
-	actual var shadowElevation: Float = 0f
-	actual var ambientShadowColor: Color = Color.Black
-	actual var spotShadowColor: Color = Color.Black
-	actual var blendMode: BlendMode = BlendMode.SrcOver
-	actual var colorFilter: ColorFilter? = null
-
-	private var outlineField: Outline = Outline.Rectangle(androidx.compose.ui.geometry.Rect.Zero)
-	actual val outline: Outline get() = outlineField
-
-	actual fun setOutsets(left: Int, top: Int, right: Int, bottom: Int) { /* no-op */ }
-	actual fun setPathOutline(path: Path) { outlineField = Outline.Generic(path) }
-	actual fun setRoundRectOutline(topLeft: Offset, size: Size, cornerRadius: Float) {
-		outlineField = Outline.Rounded(
-			androidx.compose.ui.geometry.RoundRect(
-				left = topLeft.x, top = topLeft.y,
-				right = topLeft.x + size.width, bottom = topLeft.y + size.height,
-				cornerRadius = androidx.compose.ui.geometry.CornerRadius(cornerRadius),
-			)
-		)
-	}
-	actual fun setRectOutline(topLeft: Offset, size: Size) {
-		val effTopLeft = if (topLeft == Offset.Unspecified) Offset.Zero else topLeft
-		val effSize = if (size == Size.Unspecified) this.size.let { Size(it.width.toFloat(), it.height.toFloat()) } else size
-		outlineField = Outline.Rectangle(
-			androidx.compose.ui.geometry.Rect(
-				effTopLeft.x, effTopLeft.y,
-				effTopLeft.x + effSize.width, effTopLeft.y + effSize.height,
-			)
-		)
-	}
-
-	actual var rotationX: Float = 0f
-	actual var rotationY: Float = 0f
-	actual var rotationZ: Float = 0f
-	actual var cameraDistance: Float = DefaultCameraDistance
-	actual var clip: Boolean = false
-	actual var renderEffect: RenderEffect? = null
-	actual var isReleased: Boolean = false
-		internal set
-
-	// ============
-	//  Record / draw — lambda replay
-	//
-	// Upstream's skiko actual records into a Skia Picture. This renderer is
-	// immediate-mode, so record() stores the draw lambda and draw() REPLAYS it
-	// with the layer's transform / alpha / clip applied. Same visual result as
-	// a display list as long as callers re-record on invalidation (they do —
-	// that's the GraphicsLayer contract). This is what makes GraphicsContext
-	// consumers render: SharedTransitionLayout's overlay, rememberGraphicsLayer.
-
-	private var recordedBlock: (DrawScope.() -> Unit)? = null
-	private var recordedDensity: Density = Density(1f)
-	private var recordedLayoutDirection: LayoutDirection = LayoutDirection.Ltr
-	private val drawScope = androidx.compose.ui.graphics.drawscope.CanvasDrawScope()
-
-	actual fun record(
-		density: Density,
-		layoutDirection: LayoutDirection,
-		size: IntSize,
-		block: DrawScope.() -> Unit,
-	) {
-		recordedDensity = density
-		recordedLayoutDirection = layoutDirection
-		this.size = size
-		recordedBlock = block
-	}
-
-	actual suspend fun toImageBitmap(): ImageBitmap =
-		throw NotImplementedError("GraphicsLayer.toImageBitmap not implemented on desktop")
-
-	internal actual fun draw(canvas: Canvas, parentLayer: GraphicsLayer?) {
-		if (isReleased) return
-		val vBlock = recordedBlock ?: return
-		canvas.save()
-		canvas.translate(topLeft.x.toFloat(), topLeft.y.toFloat())
-		// Transform about the pivot (defaults to the layer centre).
-		if (scaleX != 1f || scaleY != 1f || rotationZ != 0f || translationX != 0f || translationY != 0f) {
-			val vPivot =
-				if (pivotOffset == Offset.Unspecified) Offset(size.width / 2f, size.height / 2f)
-				else pivotOffset
-			canvas.translate(translationX + vPivot.x, translationY + vPivot.y)
-			if (scaleX != 1f || scaleY != 1f) canvas.scale(scaleX, scaleY)
-			if (rotationZ != 0f) canvas.rotate(rotationZ)
-			canvas.translate(-vPivot.x, -vPivot.y)
-		}
-		if (clip) {
-			// Rect/rounded outlines clip to their bounds (SDL clips are rects;
-			// rounded-corner exactness would need the offscreen mask path);
-			// generic outlines go through clipPath (bbox fallback on SDL).
-			when (val vOutline = outline) {
-				is Outline.Rectangle -> canvas.clipRect(vOutline.rect)
-				is Outline.Rounded -> canvas.clipRect(
-					androidx.compose.ui.geometry.Rect(
-						vOutline.roundRect.left, vOutline.roundRect.top,
-						vOutline.roundRect.right, vOutline.roundRect.bottom,
-					),
-				)
-				is Outline.Generic -> canvas.clipPath(vOutline.path)
-			}
-		}
-		val vNeedsAlphaLayer = alpha < 1f
-		if (vNeedsAlphaLayer) {
-			canvas.saveLayer(
-				androidx.compose.ui.geometry.Rect(0f, 0f, size.width.toFloat(), size.height.toFloat()),
-				androidx.compose.ui.graphics.Paint().apply { this.alpha = this@GraphicsLayer.alpha },
-			)
-		}
-		drawScope.draw(
-			recordedDensity,
-			recordedLayoutDirection,
-			canvas,
-			Size(size.width.toFloat(), size.height.toFloat()),
-			vBlock,
-		)
-		if (vNeedsAlphaLayer) canvas.restore()
-		canvas.restore()
-	}
-}

compose/ui/ui/src/nativeMain/kotlin/androidx/compose/ui/node/GraphicsLayerOwnerLayer.kt

@@ -0,0 +1,437 @@
+/*
+ * Copyright 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// MANUALLY VENDORED (NON-IDEMPOTENT) from compose-multiplatform-core:
+//   compose/ui/ui/src/skikoMain/.../node/GraphicsLayerOwnerLayer.skiko.kt
+// VENDOR-BASE: compose/ui/ui/src/skikoMain/kotlin/androidx/compose/ui/node/GraphicsLayerOwnerLayer.skiko.kt @ v1.12.0-beta03+dev4483
+// Change vs upstream: dropped the trailing `SkiaGraphicsContext.setLightingInfo`
+// extension + LIGHT_* constants (skiko-only shadow lighting; our shadows go via
+// NativeShadowCanvas). The class body is unchanged — it is the real OwnedLayer
+// (dirty-gated record/replay over a per-renderer GraphicsLayer), replacing the
+// immediate-mode ProjectOwnedLayer. `!`-refused in compose-fork.txt; reconcile
+// upstream changes by hand (run scripts/compose-fork/check-vendor-drift.py at each
+// COMPOSE_CORE_REF bump). See RENDERER.md Appendix A.
+package androidx.compose.ui.node
+
+import androidx.compose.ui.FrameRateCategory
+import androidx.compose.ui.geometry.MutableRect
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.isUnspecified
+import androidx.compose.ui.graphics.Canvas
+import androidx.compose.ui.graphics.CompositingStrategy
+import androidx.compose.ui.graphics.Fields
+import androidx.compose.ui.graphics.GraphicsContext
+import androidx.compose.ui.graphics.Matrix
+import androidx.compose.ui.graphics.Outline
+import androidx.compose.ui.graphics.ReusableGraphicsLayerScope
+import androidx.compose.ui.graphics.TransformOrigin
+import androidx.compose.ui.graphics.drawscope.CanvasDrawScope
+import androidx.compose.ui.graphics.drawscope.DrawScope
+import androidx.compose.ui.graphics.drawscope.drawIntoCanvas
+import androidx.compose.ui.graphics.isIdentity
+import androidx.compose.ui.graphics.layer.GraphicsLayer
+import androidx.compose.ui.graphics.layer.drawLayer
+import androidx.compose.ui.graphics.layer.setOutline
+import com.compose.sdl.graphics.prepareLayerTransformationMatrix
+import androidx.compose.ui.internal.checkPreconditionNotNull
+import androidx.compose.ui.internal.requirePrecondition
+import androidx.compose.ui.platform.invertTo
+import androidx.compose.ui.platform.isInOutline
+import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.IntOffset
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.unit.LayoutDirection
+
+/**
+ * A class representing a layer that owns and manages a `GraphicsLayer` for composable rendering.
+ *
+ * This layer is responsible for managing graphical properties, transformations, and rendering
+ * tasks associated with a `GraphicsLayer`. It provides mechanisms for updating layer properties,
+ * triggering invalidations, resizing, and mapping offsets or bounds using transformation matrices.
+ *
+ * @constructor
+ * @param graphicsLayer The initial `GraphicsLayer` for this layer.
+ * @param context The graphics context responsible for managing this layer, or `null` if externally
+ *   managed. When context is not null, it means the object is created internally, and we need to
+ *   release it during disposal.
+ * @param layerManager The manager responsible for handling the ownership and lifecycle of this layer.
+ * @param drawBlock The lambda function invoked to perform custom drawing on the canvas.
+ * @param invalidateParentLayer Callback to invalidate the parent layer when necessary.
+ */
+internal class GraphicsLayerOwnerLayer(
+    graphicsLayer: GraphicsLayer,
+    private val context: GraphicsContext?,
+    private val layerManager: OwnedLayerManager,
+    drawBlock: (canvas: Canvas, parentLayer: GraphicsLayer?) -> Unit,
+    invalidateParentLayer: () -> Unit,
+) : OwnedLayer {
+    internal var graphicsLayer: GraphicsLayer = graphicsLayer
+        private set
+    private var drawBlock: ((canvas: Canvas, parentLayer: GraphicsLayer?) -> Unit)? = drawBlock
+    private var invalidateParentLayer: (() -> Unit)? = invalidateParentLayer
+
+    private var size: IntSize = IntSize(Int.MAX_VALUE, Int.MAX_VALUE)
+    private var density = Density(1f)
+    private var layoutDirection = LayoutDirection.Ltr
+    private val scope = CanvasDrawScope()
+    private var mutatedFields: Int = 0
+    private var transformOrigin: TransformOrigin = TransformOrigin.Center
+    private var outline: Outline? = null
+
+    private val matrixCache = Matrix()
+    private var inverseMatrixCache: Matrix? = null
+
+    private var isDestroyed = false
+    private var isDirty = true
+        set(value) {
+            if (value != field) {
+                field = value
+                layerManager.notifyLayerIsDirty(this, value)
+            }
+        }
+    private var isMatrixDirty = false
+    private var isInverseMatrixDirty = false
+    private var isIdentity = true
+    override var frameRate: Float = 0f
+    override var isFrameRateFromParent = false
+
+    override fun updateLayerProperties(scope: ReusableGraphicsLayerScope) {
+        val maybeChangedFields = scope.mutatedFields or mutatedFields
+        this.layoutDirection = scope.layoutDirection
+        this.density = scope.graphicsDensity
+        if (maybeChangedFields and Fields.Outsets != 0) {
+            with(density) {
+                graphicsLayer.setOutsets(
+                    left = scope.outsets.left.roundToPx(),
+                    top = scope.outsets.top.roundToPx(),
+                    right = scope.outsets.right.roundToPx(),
+                    bottom = scope.outsets.bottom.roundToPx(),
+                )
+                invalidate()
+            }
+        }
+        if (maybeChangedFields and Fields.TransformOrigin != 0) {
+            this.transformOrigin = scope.transformOrigin
+        }
+        if (maybeChangedFields and Fields.ScaleX != 0) {
+            graphicsLayer.scaleX = scope.scaleX
+        }
+        if (maybeChangedFields and Fields.ScaleY != 0) {
+            graphicsLayer.scaleY = scope.scaleY
+        }
+        if (maybeChangedFields and Fields.Alpha != 0) {
+            graphicsLayer.alpha = scope.alpha
+        }
+        if (maybeChangedFields and Fields.TranslationX != 0) {
+            graphicsLayer.translationX = scope.translationX
+        }
+        if (maybeChangedFields and Fields.TranslationY != 0) {
+            graphicsLayer.translationY = scope.translationY
+        }
+        if (maybeChangedFields and Fields.ShadowElevation != 0) {
+            graphicsLayer.shadowElevation = scope.shadowElevation
+        }
+        if (maybeChangedFields and Fields.AmbientShadowColor != 0) {
+            graphicsLayer.ambientShadowColor = scope.ambientShadowColor
+        }
+        if (maybeChangedFields and Fields.SpotShadowColor != 0) {
+            graphicsLayer.spotShadowColor = scope.spotShadowColor
+        }
+        if (maybeChangedFields and Fields.RotationZ != 0) {
+            graphicsLayer.rotationZ = scope.rotationZ
+        }
+        if (maybeChangedFields and Fields.RotationX != 0) {
+            graphicsLayer.rotationX = scope.rotationX
+        }
+        if (maybeChangedFields and Fields.RotationY != 0) {
+            graphicsLayer.rotationY = scope.rotationY
+        }
+        if (maybeChangedFields and Fields.CameraDistance != 0) {
+            graphicsLayer.cameraDistance = scope.cameraDistance
+        }
+        if (maybeChangedFields and Fields.TransformOrigin != 0) {
+            if (transformOrigin == TransformOrigin.Center) {
+                graphicsLayer.pivotOffset = Offset.Unspecified
+            } else {
+                graphicsLayer.pivotOffset =
+                    Offset(
+                        transformOrigin.pivotFractionX * size.width,
+                        transformOrigin.pivotFractionY * size.height
+                    )
+            }
+        }
+        if (maybeChangedFields and Fields.Clip != 0) {
+            graphicsLayer.clip = scope.clip
+        }
+        if (maybeChangedFields and Fields.RenderEffect != 0) {
+            graphicsLayer.renderEffect = scope.renderEffect
+        }
+        if (maybeChangedFields and Fields.ColorFilter != 0) {
+            graphicsLayer.colorFilter = scope.colorFilter
+        }
+        if (maybeChangedFields and Fields.BlendMode != 0) {
+            graphicsLayer.blendMode = scope.blendMode
+        }
+        if (maybeChangedFields and Fields.CompositingStrategy != 0) {
+            graphicsLayer.compositingStrategy =
+                when (scope.compositingStrategy) {
+                    CompositingStrategy.Auto -> androidx.compose.ui.graphics.layer.CompositingStrategy.Auto
+                    CompositingStrategy.Offscreen -> androidx.compose.ui.graphics.layer.CompositingStrategy.Offscreen
+                    CompositingStrategy.ModulateAlpha -> androidx.compose.ui.graphics.layer.CompositingStrategy.ModulateAlpha
+                    else -> throw IllegalStateException("Not supported composition strategy")
+                }
+        }
+        if (maybeChangedFields and Fields.MatrixAffectingFields != 0) {
+            isMatrixDirty = true
+            isInverseMatrixDirty = true
+        }
+
+        var outlineChanged = false
+
+        if (outline != scope.outline) {
+            outlineChanged = true
+            outline = scope.outline
+            updateOutline()
+        }
+
+        mutatedFields = scope.mutatedFields
+        if (maybeChangedFields != 0 || outlineChanged) {
+            triggerRepaint()
+            layerManager.voteFrameRate(frameRate)
+        }
+    }
+
+    /**
+     * Triggers redrawing of Compose content during the next frame.
+     */
+    private fun triggerRepaint() {
+        layerManager.invalidate()
+    }
+
+    private fun updateOutline() {
+        val outline = outline ?: return
+        graphicsLayer.setOutline(outline)
+    }
+
+    override fun isInLayer(position: Offset): Boolean {
+        val x = position.x
+        val y = position.y
+
+        if (graphicsLayer.clip) {
+            return isInOutline(graphicsLayer.outline, x, y)
+        }
+
+        return true
+    }
+
+    override fun move(position: IntOffset) {
+        layerManager.voteFrameRate(FrameRateCategory.High.value)
+        graphicsLayer.topLeft = position
+        triggerRepaint()
+    }
+
+    override fun resize(size: IntSize) {
+        if (size != this.size) {
+            layerManager.voteFrameRate(FrameRateCategory.High.value)
+            this.size = size
+            invalidate()
+        }
+    }
+
+    override fun drawLayer(canvas: Canvas, parentLayer: GraphicsLayer?) {
+        updateDisplayList()
+        scope.drawContext.also {
+            it.canvas = canvas
+            it.graphicsLayer = parentLayer
+        }
+        scope.drawLayer(graphicsLayer)
+    }
+
+    override fun updateDisplayList() {
+        layerManager.voteFrameRate(frameRate)
+        if (isDirty) {
+            if (transformOrigin != TransformOrigin.Center && graphicsLayer.size != size) {
+                graphicsLayer.pivotOffset =
+                    Offset(
+                        transformOrigin.pivotFractionX * size.width,
+                        transformOrigin.pivotFractionY * size.height
+                    )
+            }
+            graphicsLayer.record(density, layoutDirection, size, recordLambda)
+            isDirty = false
+        }
+    }
+
+    private val recordLambda: DrawScope.() -> Unit = {
+        drawIntoCanvas { canvas ->
+            this@GraphicsLayerOwnerLayer.drawBlock?.let { it(canvas, drawContext.graphicsLayer) }
+        }
+    }
+
+    /**
+     * Marks content as dirty and triggers redrawing.
+     */
+    override fun invalidate() {
+        if (isDestroyed) return
+        isDirty = true
+        layerManager.invalidate()
+    }
+
+    override fun destroy() {
+        frameRate = 0f
+        isFrameRateFromParent = false
+        drawBlock = null
+        invalidateParentLayer = null
+        isDestroyed = true
+        isDirty = false
+        if (context != null) {
+            context.releaseGraphicsLayer(graphicsLayer)
+
+            // Recycle only in case of non-null context (meaning only for not external layers).
+            layerManager.recycle(this)
+        }
+    }
+
+    override fun mapOffset(point: Offset, inverse: Boolean): Offset {
+        val matrix =
+            if (inverse) {
+                getInverseMatrix() ?: return Offset.Infinite
+            } else {
+                getMatrix()
+            }
+        return if (isIdentity) {
+            point
+        } else {
+            matrix.map(point)
+        }
+    }
+
+    override fun mapBounds(rect: MutableRect, inverse: Boolean) {
+        val matrix = if (inverse) getInverseMatrix() else getMatrix()
+        if (!isIdentity) {
+            if (matrix == null) {
+                rect.set(0f, 0f, 0f, 0f)
+            } else {
+                matrix.map(rect)
+            }
+        }
+    }
+
+    override fun reuseLayer(
+        drawBlock: (canvas: Canvas, parentLayer: GraphicsLayer?) -> Unit,
+        invalidateParentLayer: () -> Unit
+    ) {
+        val context =
+            checkPreconditionNotNull(context) {
+                "currently reuse is only supported when we manage the layer lifecycle"
+            }
+        requirePrecondition(graphicsLayer.isReleased) {
+            "layer should have been released before reuse"
+        }
+
+        // recreate a layer
+        graphicsLayer = context.createGraphicsLayer()
+        isDestroyed = false
+
+        // apply new params
+        this.drawBlock = drawBlock
+        this.invalidateParentLayer = invalidateParentLayer
+
+        // reset mutable variables to their initial values
+        isMatrixDirty = false
+        isInverseMatrixDirty = false
+        isIdentity = true
+        matrixCache.reset()
+        inverseMatrixCache?.reset()
+        transformOrigin = TransformOrigin.Center
+        size = IntSize(Int.MAX_VALUE, Int.MAX_VALUE)
+        outline = null
+        mutatedFields = 0
+    }
+
+    override fun transform(matrix: Matrix) {
+        matrix.timesAssign(getMatrix())
+    }
+
+    override val underlyingMatrix: Matrix
+        get() = getMatrix()
+
+    override fun inverseTransform(matrix: Matrix) {
+        val inverse = getInverseMatrix()
+        if (inverse != null) {
+            matrix.timesAssign(inverse)
+        }
+    }
+
+    private fun getMatrix(): Matrix {
+        updateMatrix()
+        return matrixCache
+    }
+
+    private fun getInverseMatrix(): Matrix? {
+        val matrix = getMatrix()
+        if (isIdentity) {
+            return matrix
+        }
+
+        val inverseMatrix = inverseMatrixCache ?: Matrix().also { inverseMatrixCache = it }
+        if (!isInverseMatrixDirty) {
+            return if (inverseMatrix[0, 0].isNaN()) {
+                null
+            } else {
+                inverseMatrix
+            }
+        }
+
+        isInverseMatrixDirty = false
+        return if (matrix.invertTo(inverseMatrix)) {
+            inverseMatrix
+        } else {
+            inverseMatrix[0, 0] = Float.NaN
+            null
+        }
+    }
+
+    private fun updateMatrix() {
+        if (!isMatrixDirty) return
+        with(graphicsLayer) {
+            val pivotX: Float
+            val pivotY: Float
+            if (pivotOffset.isUnspecified) {
+                pivotX = this@GraphicsLayerOwnerLayer.size.width / 2f
+                pivotY = this@GraphicsLayerOwnerLayer.size.height / 2f
+            } else {
+                pivotX = pivotOffset.x
+                pivotY = pivotOffset.y
+            }
+            prepareLayerTransformationMatrix(
+                matrix = matrixCache,
+                pivotX = pivotX,
+                pivotY = pivotY,
+                translationX = translationX,
+                translationY = translationY,
+                rotationX = rotationX,
+                rotationY = rotationY,
+                rotationZ = rotationZ,
+                scaleX = scaleX,
+                scaleY = scaleY,
+                cameraDistance = cameraDistance
+            )
+        }
+        isMatrixDirty = false
+        isIdentity = matrixCache.isIdentity()
+    }
+}

compose/ui/ui/src/nativeMain/kotlin/androidx/compose/ui/text/SdlParagraph.native.kt

@@ -17,6 +17,7 @@ import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.text.style.TextDecoration
 import androidx.compose.ui.unit.Constraints
 import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.TextUnitType
 import androidx.compose.ui.unit.isUnspecified
 import com.compose.sdl.text.NativeTextCanvas
 import com.compose.sdl.text.currentTextMeasurer
@@ -73,7 +74,32 @@ internal class SdlParagraph(
 	private val wrapped = currentTextMeasurer.wrap(text, fontPx, maxWidthPx, family, variations)
 	private val allLines: List<String> = wrapped.lines
 	private val lineStarts: IntArray = wrapped.lineStarts
-	private val lh: Float = currentTextMeasurer.lineHeight(fontPx, family, variations).coerceAtLeast(1f)
+
+	// TextStyle.lineHeight in px — upstream Skia paragraphs honour it (every M3
+	// Typography style sets one, e.g. bodyMedium 14sp/20sp), so ignoring it made every
+	// text block's height differ from upstream by ~1px per WRAPPED line, an error that
+	// ACCUMULATED down the page (the dominant term in every parity diff). sp scales by
+	// density like fontPx; em multiplies the font size.
+	private val styleLineHeightPx: Float? = when {
+		style.lineHeight.isUnspecified -> null
+		style.lineHeight.type == TextUnitType.Sp -> style.lineHeight.value * density
+		style.lineHeight.type == TextUnitType.Em -> style.lineHeight.value * fontPx
+		else -> null
+		// Upstream ignores a lineHeight NOT STRICTLY GREATER than the font size (skia
+		// only applies height multipliers > 1em) — probe: 48sp/24lh -> the 65px cell,
+		// and 24sp/24lh (h = 1.0 exactly) -> the 33px cell, while 24sp/25lh -> 25.
+	}?.takeIf { it > fontPx }
+	// How the band applies depends on TextStyle.lineHeightStyle (probe-verified vs JVM):
+	// - unspecified (raw BasicText): COMPAT TRIM — the first line keeps the tight font
+	//   cell, lineHeight is the advance between baselines. n lines = cell + (n-1)*lh.
+	// - Trim.None (every M3 Typography style: Center/None/Fixed): UNIFORM bands — every
+	//   line is exactly lineHeight, single-line included (even below the cell).
+	private val uniformBands: Boolean =
+		style.lineHeightStyle?.trim == androidx.compose.ui.text.style.LineHeightStyle.Trim.None
+	private val fontCellH: Float =
+		currentTextMeasurer.lineHeight(fontPx, family, variations).coerceAtLeast(1f)
+	private val lh: Float = styleLineHeightPx ?: fontCellH
+	private val firstLineH: Float = if (uniformBands && styleLineHeightPx != null) lh else fontCellH
 
 	// True when a span changes glyph METRICS (fontSize / fontWeight) — gates
 	// the styled measurement paths so plain/colour-only text keeps the cheap
@@ -103,10 +129,14 @@ internal class SdlParagraph(
 	// Per-line box heights: base line height unless a size span makes a line's
 	// tallest run cell bigger. lineTops[i] = cumulative top; last entry = height.
 	private val lineHeights: FloatArray by lazy {
-		if (!metricSpans) FloatArray(lineCount) { lh }
+		if (!metricSpans) FloatArray(lineCount) { if (it == 0) firstLineH else lh }
 		else FloatArray(lineCount) {
-			styledLineCellHeight(allLines[it], lineStarts[it], spanStyles, fontPx, density, currentTextMeasurer, family, variations)
-				.coerceAtLeast(1f)
+			// A size span can push a line's cell above the style's line height, but
+			// never below it (first line keeps its tight cell under compat trim).
+			max(
+				styledLineCellHeight(allLines[it], lineStarts[it], spanStyles, fontPx, density, currentTextMeasurer, family, variations),
+				if (it == 0 && !uniformBands) 0f else (styleLineHeightPx ?: 0f),
+			).coerceAtLeast(1f)
 		}
 	}
 	private val lineTops: FloatArray by lazy {
@@ -118,7 +148,9 @@ internal class SdlParagraph(
 	override val width: Float by lazy {
 		if (maxWidthPx == Int.MAX_VALUE) (lineWidths.maxOrNull() ?: 0f) else widthConstraint
 	}
-	override val height: Float by lazy { if (!metricSpans) lineCount * lh else lineTops[lineCount] }
+	override val height: Float by lazy {
+		if (!metricSpans) firstLineH + (lineCount - 1) * lh else lineTops[lineCount]
+	}
 	// Widest single HARD-BREAK line — NOT the concatenated all-on-one-line width.
 	// Compose's Text(softWrap = false) reads this to decide the paragraph width
 	// (LayoutUtils.finalMaxWidth returns Constraints.Infinity when softWrap=false,
@@ -193,8 +225,9 @@ internal class SdlParagraph(
 	}
 
 	override fun getLineForVerticalPosition(vertical: Float): Int {
-		if (!metricSpans) return (vertical / lh).toInt().coerceIn(0, lineCount - 1)
 		// Cumulative tops are monotonic — walk to the line containing `vertical`.
+		// (No uniform-divide fast path anymore: the first line's box is the font
+		// cell while later lines use the style lineHeight.)
 		for (i in 0 until lineCount) if (vertical < lineTops[i + 1]) return i
 		return lineCount - 1
 	}
@@ -368,6 +401,8 @@ internal class SdlParagraph(
 			inFontVariations = variations,
 			inBaseItalic = style.fontStyle == androidx.compose.ui.text.font.FontStyle.Italic,
 			inTextDecoration = inDecoration ?: style.textDecoration,
+			inLineHeightPx = lh,
+			inTrimFirstLine = !uniformBands || styleLineHeightPx == null,
 		)
 	}
 

compose/ui/ui/src/nativeMain/kotlin/com/compose/sdl/RenderBackend.kt

@@ -31,11 +31,13 @@ interface RenderBackend {
        so it maps 1:1 onto the pixel back buffer. */
     fun beginFrame(inDpr: Float)
 
-    /* Draw the upstream LayoutNode tree owned by [inHost] through the vendored
-       coordinator / DrawModifierNode pipeline (LayoutNode.draw → CanvasDrawScope
-       → the platform Canvas backend). Default no-op — the Skia backend will
-       override once SkiaCanvas lands (see NODE_ENGINE_PORT.md Phase 9). */
-    fun drawRoot(inHost: com.compose.sdl.node.ComposeRootHost) {}
+    /* Build this frame's platform Canvas and hand it to [inDraw], which walks the
+       composition (host.drawRoot(canvas)) through the vendored coordinator /
+       DrawModifierNode pipeline. Taking a (Canvas)->Unit instead of the host keeps
+       RenderBackend + its implementations independent of the node/host layer — the
+       decoupling that lets the renderers live in :ui-graphics (no ui-graphics→ui
+       cycle). Default no-op. */
+    fun drawRoot(inDraw: (canvas: androidx.compose.ui.graphics.Canvas) -> Unit) {}
 
     /* Flush + present whatever was just drawn. */
     fun endFrame()

compose/ui/ui/src/nativeMain/kotlin/com/compose/sdl/graphics/GraphicsContextFactory.kt

@@ -0,0 +1,14 @@
+package com.compose.sdl.graphics
+
+import androidx.compose.ui.graphics.GraphicsContext
+
+// ==================
+// MARK: GraphicsContext factory seam (B2 / P1.3)
+// ==================
+
+/* ComposeOwner.graphicsContext is created behind a per-renderer factory seam so each
+   leg supplies its own GraphicsContext: exactly one actual is attached per target
+   (the createRenderBackend trick). SDL → the project ProjectGraphicsContext (record/
+   replay via the SDL NativeRenderNode); Skia → upstream's SkiaGraphicsContext (owns a
+   skiko RenderNodeContext). See RENDERER.md §4 (B2). */
+internal expect fun createGraphicsContext(): GraphicsContext

compose/ui/ui/src/nativeMain/kotlin/com/compose/sdl/graphics/GraphicsLayerFactory.native.kt

@@ -1,13 +0,0 @@
-package com.compose.sdl.graphics
-
-import androidx.compose.ui.graphics.layer.GraphicsLayer
-
-// ==================
-// MARK: GraphicsLayer factory — native actuals
-// ==================
-
-internal actual fun createProjectGraphicsLayer(): GraphicsLayer = GraphicsLayer()
-
-internal actual fun releaseProjectGraphicsLayer(inLayer: GraphicsLayer) {
-	inLayer.isReleased = true
-}

compose/ui/ui/src/nativeMain/kotlin/com/compose/sdl/graphics/LayerTransformationMatrix.kt

@@ -0,0 +1,67 @@
+package com.compose.sdl.graphics
+
+import androidx.compose.ui.graphics.Matrix
+import kotlin.math.abs
+
+// Layer transform matrix builder for GraphicsLayerOwnerLayer (hit-testing /
+// coordinate mapping). Body vendored from compose-multiplatform-core
+// Matrices.skiko.kt `prepareTransformationMatrix` — pure Compose `Matrix` math,
+// no Skia. It lives HERE in nativeMain (shared by both renderer legs) under a
+// distinct name so it is visible to GraphicsLayerOwnerLayer (also nativeMain);
+// the upstream `prepareTransformationMatrix` stays skikoRenderer-only in the
+// vendored Matrices.skiko.kt and would not be visible up here. Distinct name
+// avoids clashing with that copy on the Skia leg. (RENDERER.md P1.5 will
+// reverse this rename once B2 vendors Matrices.skiko onto the Skia leg.)
+// VENDOR-BASE: compose/ui/ui/src/skikoMain/kotlin/androidx/compose/ui/graphics/Matrices.skiko.kt @ v1.12.0-beta03+dev4483
+
+// Builds the layer transform (translation / rotation / scale / camera about a
+// pivot) into [matrix]. Matches the skiko copy so hit-testing agrees across legs.
+internal fun prepareLayerTransformationMatrix(
+	matrix: Matrix,
+	pivotX: Float,
+	pivotY: Float,
+	translationX: Float,
+	translationY: Float,
+	rotationX: Float,
+	rotationY: Float,
+	rotationZ: Float,
+	scaleX: Float,
+	scaleY: Float,
+	cameraDistance: Float,
+) {
+	matrix.reset()
+	matrix.translate(x = -pivotX, y = -pivotY)
+	matrix *= Matrix().apply {
+		rotateZ(rotationZ)
+		rotateY(rotationY)
+		rotateX(rotationX)
+		scale(scaleX, scaleY)
+	}
+	// Perspective transform should be applied only in case of rotations to avoid
+	// multiply application in hierarchies.
+	// See Android's frameworks/base/libs/hwui/RenderProperties.cpp for reference
+	if (!rotationX.isZero() || !rotationY.isZero()) {
+		matrix *= Matrix().apply {
+			// The camera location is passed in inches, set in pt
+			val depth = cameraDistance * 72f
+			this[2, 3] = -1f / depth
+		}
+	}
+	matrix *= Matrix().apply {
+		translate(x = pivotX + translationX, y = pivotY + translationY)
+	}
+
+	// Third column and row are irrelevant for 2D space.
+	// Zeroing required to get correct inverse transformation matrix.
+	matrix[2, 0] = 0f
+	matrix[2, 1] = 0f
+	matrix[2, 3] = 0f
+	matrix[0, 2] = 0f
+	matrix[1, 2] = 0f
+	matrix[3, 2] = 0f
+}
+
+private const val NON_ZERO_EPSILON = 0.001f
+
+@Suppress("NOTHING_TO_INLINE")
+private inline fun Float.isZero(): Boolean = abs(this) <= NON_ZERO_EPSILON

compose/ui/ui/src/nativeMain/kotlin/com/compose/sdl/node/ComposeRootHost.kt

@@ -65,12 +65,36 @@ class ComposeRootHost(inDensity: Float = 1f) {
 		fOwner.animationFrameClock.sendFrame(inNanos)
 	}
 
+	// True while a node-level animation (scroll fling, node Animatable) awaits the next
+	// animation frame — the node half of the window's quiescence signal (render-to-quiescence
+	// screenshot capture asks the window whether ANY work is still pending).
+	fun hasAnimationAwaiters(): Boolean = fOwner.animationFrameClock.hasAwaiters
+
 	fun measureAndLayout() {
 		// Flush deferred end-of-apply work (focus invalidation etc.) before measuring, so
 		// requestFocus() from composition OR from a pointer event this frame takes effect —
 		// e.g. focus-on-click, which schedules a focus invalidation during event dispatch.
 		fOwner.onEndApplyChanges()
 		fOwner.measureAndLayout()
+		// Drop snapshot observations whose scope is no longer valid (detached nodes,
+		// destroyed layers, disposed draw scopes). Upstream RootNodeOwner does this after
+		// the measure pass; without it, every disposed subtree's measure/layout/DRAW
+		// observation scopes linger in the OwnerSnapshotObserver forever — each pins its
+		// observed object graph (a leak the P2.2 soak caught on ripple/indication draws).
+		fOwner.snapshotObserver.clearInvalidObservations()
+	}
+
+	// Draw the composed tree into [canvas] — re-records dirty layers, then walks
+	// the root so clean layers replay their cached content. Backends call this
+	// instead of rootNode.draw so retained-layer bookkeeping runs each frame.
+	fun drawRoot(canvas: androidx.compose.ui.graphics.Canvas) {
+		fOwner.renderRoot(canvas)
+	}
+
+	// The window wires this to set needsFrame — a layer whose content changed
+	// (OwnedLayer.invalidate) schedules a frame even with nothing else pending.
+	fun setInvalidationCallback(callback: () -> Unit) {
+		fOwner.onInvalidate = callback
 	}
 
 	// The owner's FocusOwner IS a FocusManager — the window provides it as LocalFocusManager.
@@ -138,29 +162,8 @@ class ComposeRootHost(inDensity: Float = 1f) {
 	fun onDropComplete() = fOwner.dragAndDropManager.dropComplete()
 }
 
-// ==================
-// MARK: pointer-event bridge (nativeMain builds the internal PointerInputEvent)
-// ==================
-
-/* The internal `expect PointerInputEvent` exposes no commonMain constructor, so the
-   build+dispatch is a nativeMain actual. Constructs a single-pointer event and feeds it
-   to the owner's PointerInputEventProcessor. inType: 0=Move 1=Press 2=Release. */
-internal expect fun feedPointerToProcessor(
-	inOwner: com.compose.sdl.node.impl.ComposeOwner,
-	inType: Int,
-	inButton: Int,
-	inUptime: Long,
-	inX: Float,
-	inY: Float,
-)
-
-/* Builds a Scroll-type PointerInputEvent (scrollDelta) and drives the processor, so the vendored
-   Modifier.scrollable's MouseWheelScrollingLogic handles the wheel. nativeMain-only (ctor is native). */
-internal expect fun feedScrollToProcessor(
-	inOwner: com.compose.sdl.node.impl.ComposeOwner,
-	inX: Float,
-	inY: Float,
-	inDeltaX: Float,
-	inDeltaY: Float,
-	inUptime: Long,
-)
+// NOTE: feedPointerToProcessor / feedScrollToProcessor are plain nativeMain
+// functions in PointerEventBridge.native.kt. This facade moved from commonMain to
+// nativeMain (it now constructs the native retained-layer OwnedLayer via
+// ComposeOwner), so the former expect/actual split collapsed to a single native
+// definition — see RENDERER.md §5.

compose/ui/ui/src/nativeMain/kotlin/com/compose/sdl/node/PointerEventBridge.native.kt

@@ -25,7 +25,7 @@ private var fTertiaryDown = false
 /* Builds the internal PointerInputEvent (its constructor is native-only) from a single mouse
    pointer and drives the owner's PointerInputEventProcessor. inType: 0=Move 1=Press 2=Release;
    inButton: 0=primary 1=secondary 2=tertiary. */
-internal actual fun feedPointerToProcessor(
+internal fun feedPointerToProcessor(
 	inOwner: ComposeOwner,
 	inType: Int,
 	inButton: Int,
@@ -82,7 +82,7 @@ internal actual fun feedPointerToProcessor(
    vendored Modifier.scrollable (MouseWheelScrollingLogic) consumes it. SDL wheel delta maps
    directly to scrollDelta (wheel-down = SDL deltaY<0 → content scrolls down); magnitude is scaled
    in Sdl3ScrollConfig (dp per notch). */
-internal actual fun feedScrollToProcessor(
+internal fun feedScrollToProcessor(
 	inOwner: ComposeOwner,
 	inX: Float,
 	inY: Float,

compose/ui/ui/src/nativeMain/kotlin/com/compose/sdl/node/impl/ComposeOwner.kt

@@ -9,6 +9,8 @@ import androidx.compose.ui.node.LayoutNodeDrawScope
 import androidx.compose.ui.node.MeasureAndLayoutDelegate
 import androidx.compose.ui.node.Owner
 import androidx.compose.ui.node.OwnedLayer
+import androidx.compose.ui.node.OwnedLayerManager
+import androidx.compose.ui.node.GraphicsLayerOwnerLayer
 import androidx.compose.ui.node.OwnerScope
 import androidx.compose.ui.node.OwnerSnapshotObserver
 import androidx.compose.ui.node.RootForTest
@@ -79,7 +81,7 @@ internal class ComposeOwner(
 	override val root: LayoutNode,
 	override val density: Density = Density(1f, 1f),
 	override val layoutDirection: LayoutDirection = LayoutDirection.Ltr,
-) : Owner {
+) : Owner, OwnedLayerManager {
 
 	// The vendored measure/layout state machine, rooted at [root].
 	private val fDelegate = MeasureAndLayoutDelegate(root)
@@ -151,6 +153,11 @@ internal class ComposeOwner(
 
 	override fun onDetach(node: LayoutNode) {
 		fDelegate.onNodeDetached(node)
+		// Drop the detached node's read-observation scopes, exactly as upstream
+		// RootNodeOwner.onDetach does. Without this, every disposed node's measure/
+		// layout/draw observation scopes accumulate in the snapshot observer forever
+		// — the baseline composition-machinery leak the P2.2 soak caught.
+		snapshotObserver.clear(node)
 	}
 
 	override fun registerOnLayoutCompletedListener(listener: Owner.OnLayoutCompletedListener) {
@@ -176,7 +183,86 @@ internal class ComposeOwner(
 		drawBlock: (canvas: Canvas, parentLayer: GraphicsLayer?) -> Unit,
 		invalidateParentLayer: () -> Unit,
 		explicitLayer: GraphicsLayer?,
-	): OwnedLayer = ProjectOwnedLayer(drawBlock)
+	): OwnedLayer = GraphicsLayerOwnerLayer(
+		graphicsLayer = explicitLayer ?: graphicsContext.createGraphicsLayer(),
+		context = if (explicitLayer != null) null else graphicsContext,
+		layerManager = this,
+		drawBlock = drawBlock,
+		invalidateParentLayer = invalidateParentLayer,
+	)
+
+	// ============
+	//  OwnedLayerManager — retained-layer bookkeeping (mirrors upstream
+	//  OwnedLayerManagerImpl). dirtyLayers are re-recorded once per frame in
+	//  [renderRoot] before the tree is drawn; clean layers replay their cached
+	//  display list. invalidate() asks the window to schedule a frame.
+
+	private val dirtyLayers = mutableListOf<OwnedLayer>()
+	private var postponedDirtyLayers: MutableList<OwnedLayer>? = null
+	private var isDrawingContent = false
+
+	// Set by the window (via ComposeRootHost) to flag needsFrame; a layer whose
+	// content changed (OwnedLayer.invalidate) schedules a frame even when nothing
+	// else (recompose / relayout) is pending.
+	internal var onInvalidate: (() -> Unit)? = null
+
+	override fun invalidate() {
+		onInvalidate?.invoke()
+	}
+
+	override fun notifyLayerIsDirty(layer: OwnedLayer, isDirty: Boolean) {
+		// Mirrors upstream OwnedLayerManagerImpl exactly. The CRITICAL detail: when a
+		// layer clears its dirty flag DURING drawing (updateDisplayList sets isDirty
+		// = false in the renderRoot loop), we must NOT remove it from dirtyLayers here
+		// — that would shrink the list mid-iteration (IndexOutOfBounds). renderRoot's
+		// dirtyLayers.clear() after the loop handles it instead.
+		if (!isDirty) {
+			if (!isDrawingContent) {
+				dirtyLayers.remove(layer)
+				postponedDirtyLayers?.remove(layer)
+			}
+		} else if (!isDrawingContent) {
+			dirtyLayers += layer
+		} else {
+			val postponed = postponedDirtyLayers
+				?: mutableListOf<OwnedLayer>().also { postponedDirtyLayers = it }
+			postponed += layer
+		}
+	}
+
+	override fun recycle(layer: OwnedLayer): Boolean {
+		dirtyLayers.remove(layer)
+		postponedDirtyLayers?.remove(layer)
+		return false
+	}
+
+	// Both Owner and OwnedLayerManager declare voteFrameRate with a default, so an
+	// explicit override is required. We render at a fixed vsync cadence — no voting.
+	override fun voteFrameRate(frameRate: Float) {}
+
+	// Draw the tree: re-record dirty layers' display lists, then walk the root so
+	// clean layers replay. Called once per frame by ComposeRootHost.drawRoot.
+	internal fun renderRoot(canvas: Canvas) {
+		isDrawingContent = true
+		// Re-record dirty layers BEFORE drawing (unlike Android, our draw forms the
+		// actual render-command sequence, so display lists must be current first).
+		// notifyLayerIsDirty(false) is a no-op while drawing, so the list can't shrink
+		// here; clear() below drops them all at once.
+		if (dirtyLayers.isNotEmpty()) {
+			for (i in 0 until dirtyLayers.size) {
+				dirtyLayers[i].updateDisplayList()
+			}
+		}
+		dirtyLayers.clear()
+		root.draw(canvas, null)
+		// Layers that invalidated themselves during draw were parked in postponed;
+		// roll them into next frame.
+		postponedDirtyLayers?.let {
+			dirtyLayers.addAll(it)
+			it.clear()
+		}
+		isDrawingContent = false
+	}
 
 	// ============
 	//  No-op subsystems (focus / semantics / input / clipboard / text / …).
@@ -216,17 +302,12 @@ internal class ComposeOwner(
 			containsControls: Boolean,
 		): Long = originalTimeoutMillis
 	}
-	// GraphicsLayer here is the project record/replay actual (see
-	// GraphicsLayer.native.kt) — SharedTransitionLayout overlays and
-	// rememberGraphicsLayer() create layers through this context. The
-	// expect class hides its constructor/release from commonMain, hence
-	// the project factory hops.
-	override val graphicsContext: GraphicsContext = object : GraphicsContext {
-		override fun createGraphicsLayer(): GraphicsLayer =
-			com.compose.sdl.graphics.createProjectGraphicsLayer()
-		override fun releaseGraphicsLayer(layer: GraphicsLayer) =
-			com.compose.sdl.graphics.releaseProjectGraphicsLayer(layer)
-	}
+	// Created behind a per-renderer factory seam (B2 / P1.3): SDL uses the project
+	// record/replay GraphicsContext; the Skia leg swaps in upstream's SkiaGraphicsContext
+	// at P1.6. SharedTransitionLayout overlays and rememberGraphicsLayer() create layers
+	// through this context. See com/compose/sdl/graphics/GraphicsContextFactory.kt.
+	override val graphicsContext: GraphicsContext =
+		com.compose.sdl.graphics.createGraphicsContext()
 	override val textToolbar: TextToolbar = object : TextToolbar {
 		override val status: androidx.compose.ui.platform.TextToolbarStatus
 			get() = androidx.compose.ui.platform.TextToolbarStatus.Hidden

compose/ui/ui/src/sdlRendererMain/kotlin/androidx/compose/ui/graphics/layer/GraphicsLayer.native.kt

@@ -0,0 +1,321 @@
+package androidx.compose.ui.graphics.layer
+
+import androidx.compose.ui.geometry.CornerRadius
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.Rect
+import androidx.compose.ui.geometry.RoundRect
+import androidx.compose.ui.geometry.Size
+import androidx.compose.ui.geometry.isUnspecified
+import androidx.compose.ui.graphics.BlendMode
+import androidx.compose.ui.graphics.Canvas
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.ColorFilter
+import androidx.compose.ui.graphics.ImageBitmap
+import androidx.compose.ui.graphics.Outline
+import androidx.compose.ui.graphics.Path
+import androidx.compose.ui.graphics.RenderEffect
+import androidx.compose.ui.graphics.drawscope.DrawScope
+import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.IntOffset
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.unit.LayoutDirection
+import androidx.compose.ui.unit.toSize
+import com.compose.sdl.graphics.NativeRenderNode
+
+// ==================
+// MARK: GraphicsLayer — façade over NativeRenderNode
+// ==================
+//
+// DERIVED (copy + edit) from compose-multiplatform-core
+//   ui-graphics/src/skikoMain/.../graphics/layer/SkiaGraphicsLayer.skiko.kt.
+// VENDOR-BASE: compose/ui/ui-graphics/src/skikoMain/kotlin/androidx/compose/ui/graphics/layer/SkiaGraphicsLayer.skiko.kt @ v1.12.0-beta03+dev4483
+// The ONLY structural change vs upstream: the backing display-list node is our
+// renderer-agnostic `NativeRenderNode` instead of `org.jetbrains.skiko.node.RenderNode`,
+// so both renderers share this façade (Skia's node wraps the real skiko RenderNode;
+// SDL's node is SdlRenderNode). Every visual property is mirrored onto the node and
+// applied at replay, exactly like upstream. Trimmed vs upstream: outsets (blur
+// expansion) and ChildLayerDependenciesTracker (prompt child release — our children
+// release via NativeReleaseQueue/GC instead). See RENDERER.md §4 (B2).
+
+@Suppress("PropertyName")
+actual class GraphicsLayer internal constructor(
+	private val renderNode: NativeRenderNode,
+) {
+
+	private var outlineDirty = true
+	private var roundRectOutlineTopLeft: Offset = Offset.Zero
+	private var roundRectOutlineSize: Size = Size.Unspecified
+	private var roundRectCornerRadius: Float = 0f
+	private var internalOutline: Outline? = null
+	private var outlinePath: Path? = null
+
+	actual var compositingStrategy: CompositingStrategy = CompositingStrategy.Auto
+		set(value) {
+			if (field != value) {
+				field = value
+				renderNode.compositingStrategy = value
+			}
+		}
+
+	actual var topLeft: IntOffset = IntOffset.Zero
+		set(value) {
+			if (field != value) {
+				field = value
+				renderNode.topLeft = value
+			}
+		}
+
+	actual var size: IntSize = IntSize.Zero
+		private set(value) {
+			if (field != value) {
+				field = value
+				renderNode.size = value
+				if (roundRectOutlineSize.isUnspecified) {
+					outlineDirty = true
+					configureOutlineAndClip()
+				}
+			}
+		}
+
+	actual var pivotOffset: Offset = Offset.Unspecified
+		set(value) {
+			if (field != value) {
+				field = value
+				renderNode.pivot = value
+			}
+		}
+
+	actual var alpha: Float = 1f
+		set(value) {
+			if (field != value) {
+				field = value
+				renderNode.alpha = value
+			}
+		}
+
+	actual var scaleX: Float = 1f
+		set(value) {
+			if (field != value) { field = value; renderNode.scaleX = value }
+		}
+
+	actual var scaleY: Float = 1f
+		set(value) {
+			if (field != value) { field = value; renderNode.scaleY = value }
+		}
+
+	actual var translationX: Float = 0f
+		set(value) {
+			if (field != value) { field = value; renderNode.translationX = value }
+		}
+
+	actual var translationY: Float = 0f
+		set(value) {
+			if (field != value) { field = value; renderNode.translationY = value }
+		}
+
+	actual var shadowElevation: Float = 0f
+		set(value) {
+			if (field != value) {
+				field = value
+				renderNode.shadowElevation = value
+				outlineDirty = true
+				configureOutlineAndClip()
+			}
+		}
+
+	actual var ambientShadowColor: Color = Color.Black
+		set(value) {
+			if (field != value) { field = value; renderNode.ambientShadowColor = value }
+		}
+
+	actual var spotShadowColor: Color = Color.Black
+		set(value) {
+			if (field != value) { field = value; renderNode.spotShadowColor = value }
+		}
+
+	actual var blendMode: BlendMode = BlendMode.SrcOver
+		set(value) {
+			if (field != value) { field = value; renderNode.blendMode = value }
+		}
+
+	actual var colorFilter: ColorFilter? = null
+		set(value) {
+			if (field != value) { field = value; renderNode.colorFilter = value }
+		}
+
+	actual val outline: Outline
+		get() {
+			val tmpOutline = internalOutline
+			val tmpPath = outlinePath
+			return if (tmpOutline != null) {
+				tmpOutline
+			} else if (tmpPath != null) {
+				Outline.Generic(tmpPath).also { internalOutline = it }
+			} else {
+				resolveOutlinePosition { outlineTopLeft, outlineSize ->
+					val left = outlineTopLeft.x
+					val top = outlineTopLeft.y
+					val right = left + outlineSize.width
+					val bottom = top + outlineSize.height
+					val cornerRadius = this.roundRectCornerRadius
+					if (cornerRadius > 0f) {
+						Outline.Rounded(RoundRect(left, top, right, bottom, CornerRadius(cornerRadius)))
+					} else {
+						Outline.Rectangle(Rect(left, top, right, bottom))
+					}
+				}.also { internalOutline = it }
+			}
+		}
+
+	private fun resetOutlineParams() {
+		internalOutline = null
+		outlinePath = null
+		roundRectOutlineSize = Size.Unspecified
+		roundRectOutlineTopLeft = Offset.Zero
+		roundRectCornerRadius = 0f
+		outlineDirty = true
+	}
+
+	actual fun setPathOutline(path: Path) {
+		resetOutlineParams()
+		this.outlinePath = path
+		configureOutlineAndClip()
+	}
+
+	actual fun setRoundRectOutline(topLeft: Offset, size: Size, cornerRadius: Float) {
+		if (this.roundRectOutlineTopLeft != topLeft ||
+			this.roundRectOutlineSize != size ||
+			this.roundRectCornerRadius != cornerRadius ||
+			this.outlinePath != null
+		) {
+			resetOutlineParams()
+			this.roundRectOutlineTopLeft = topLeft
+			this.roundRectOutlineSize = size
+			this.roundRectCornerRadius = cornerRadius
+			configureOutlineAndClip()
+		}
+	}
+
+	actual fun setRectOutline(topLeft: Offset, size: Size) {
+		setRoundRectOutline(topLeft, size, 0f)
+	}
+
+	actual var rotationX: Float = 0f
+		set(value) {
+			if (field != value) { field = value; renderNode.rotationX = value }
+		}
+
+	actual var rotationY: Float = 0f
+		set(value) {
+			if (field != value) { field = value; renderNode.rotationY = value }
+		}
+
+	actual var rotationZ: Float = 0f
+		set(value) {
+			if (field != value) { field = value; renderNode.rotationZ = value }
+		}
+
+	actual var cameraDistance: Float = DefaultCameraDistance
+		set(value) {
+			if (field != value) { field = value; renderNode.cameraDistance = value }
+		}
+
+	actual var clip: Boolean = false
+		set(value) {
+			if (field != value) {
+				field = value
+				renderNode.clip = value
+				outlineDirty = true
+				configureOutlineAndClip()
+			}
+		}
+
+	actual var renderEffect: RenderEffect? = null
+		set(value) {
+			if (field != value) { field = value; renderNode.renderEffect = value }
+		}
+
+	actual var isReleased: Boolean = false
+		internal set
+
+	actual fun setOutsets(left: Int, top: Int, right: Int, bottom: Int) {
+		// Outsets (blur/shadow expansion) not modelled on this port — see header.
+	}
+
+	actual fun record(
+		density: Density,
+		layoutDirection: LayoutDirection,
+		size: IntSize,
+		block: DrawScope.() -> Unit,
+	) {
+		this.size = size
+		renderNode.record(density, layoutDirection, size, block)
+	}
+
+	internal actual fun draw(canvas: Canvas, parentLayer: GraphicsLayer?) {
+		if (isReleased) return
+		configureOutlineAndClip()
+		renderNode.drawInto(canvas)
+	}
+
+	@OptIn(androidx.compose.ui.InternalComposeUiApi::class)
+	private fun configureOutlineAndClip() {
+		if (!outlineDirty) return
+		val outlineIsNeeded = clip || shadowElevation > 0f
+		if (!outlineIsNeeded) {
+			renderNode.clip = false
+			renderNode.setClipPath(null)
+		} else {
+			renderNode.clip = clip
+			when (val tmpOutline = outline) {
+				is Outline.Rectangle -> renderNode.setClipRect(
+					tmpOutline.rect.left, tmpOutline.rect.top,
+					tmpOutline.rect.right, tmpOutline.rect.bottom,
+				)
+				is Outline.Rounded -> renderNode.setClipRRect(
+					tmpOutline.roundRect.left, tmpOutline.roundRect.top,
+					tmpOutline.roundRect.right, tmpOutline.roundRect.bottom,
+					floatArrayOf(
+						tmpOutline.roundRect.topLeftCornerRadius.x,
+						tmpOutline.roundRect.topLeftCornerRadius.y,
+						tmpOutline.roundRect.topRightCornerRadius.x,
+						tmpOutline.roundRect.topRightCornerRadius.y,
+						tmpOutline.roundRect.bottomRightCornerRadius.x,
+						tmpOutline.roundRect.bottomRightCornerRadius.y,
+						tmpOutline.roundRect.bottomLeftCornerRadius.x,
+						tmpOutline.roundRect.bottomLeftCornerRadius.y,
+					),
+				)
+				is Outline.Generic -> renderNode.setClipPath(tmpOutline.path)
+			}
+		}
+		outlineDirty = false
+	}
+
+	private inline fun <T> resolveOutlinePosition(block: (Offset, Size) -> T): T {
+		val layerSize = this.size.toSize()
+		val rRectTopLeft = roundRectOutlineTopLeft
+		val rRectSize = roundRectOutlineSize
+		val outlineSize = if (rRectSize.isUnspecified) layerSize else rRectSize
+		return block(rRectTopLeft, outlineSize)
+	}
+
+	internal fun release() {
+		if (!isReleased) {
+			isReleased = true
+			renderNode.close()
+		}
+	}
+
+	// Mirrors upstream SkiaGraphicsLayer.toImageBitmap: render the layer into a fresh
+	// bitmap of its own size. The offscreen canvas is flushed via NativeFinishableCanvas
+	// (SDL batches geometry; the backing render-target texture must be committed before
+	// it's read) — Skia's finish() is a no-op.
+	actual suspend fun toImageBitmap(): ImageBitmap {
+		val bitmap = ImageBitmap(size.width, size.height)
+		val canvas = Canvas(bitmap)
+		draw(canvas, null)
+		(canvas as? com.compose.sdl.graphics.NativeFinishableCanvas)?.finish()
+		return bitmap
+	}
+}

compose/ui/ui/src/sdlRendererMain/kotlin/com/compose/sdl/graphics/DeferredRenderNode.kt

@@ -0,0 +1,201 @@
+package com.compose.sdl.graphics
+
+import androidx.compose.ui.geometry.CornerRadius
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.Rect
+import androidx.compose.ui.geometry.RoundRect
+import androidx.compose.ui.geometry.Size
+import androidx.compose.ui.geometry.isUnspecified
+import androidx.compose.ui.graphics.BlendMode
+import androidx.compose.ui.graphics.Canvas
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.ColorFilter
+import androidx.compose.ui.graphics.Matrix
+import androidx.compose.ui.graphics.Outline
+import androidx.compose.ui.graphics.Paint
+import androidx.compose.ui.graphics.Path
+import androidx.compose.ui.graphics.RenderEffect
+import androidx.compose.ui.graphics.drawscope.CanvasDrawScope
+import androidx.compose.ui.graphics.drawscope.DrawScope
+import androidx.compose.ui.graphics.layer.CompositingStrategy
+import androidx.compose.ui.graphics.layer.DefaultCameraDistance
+import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.IntOffset
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.unit.LayoutDirection
+
+// ==================
+// MARK: DeferredRenderNode — replay-the-block NativeRenderNode
+// ==================
+
+/*
+ The renderer-agnostic [NativeRenderNode] both renderers use today. It does NOT
+ cache rasterised output: [record] stores the draw block; [drawInto] REPLAYS it
+ against the target canvas under the node's transform / clip / shadow / alpha. This
+ is behaviour-identical to the pre-refactor paths it replaces — the old
+ GraphicsLayer.native lambda-replay AND ProjectOwnedLayer's transform/shadow/clip —
+ now unified in one place behind the RenderNode seam.
+
+ It is the correct-but-unoptimised node. The perf win (stop re-tessellating on
+ replay) comes from swapping the per-renderer createNativeRenderNode actual to a
+ caching node — skiko RenderNode (a real display list) on Skia, an offscreen /
+ cached-geometry display list on SDL — WITHOUT touching GraphicsLayer. See
+ RENDERER.md §4 (Phase 2 = that swap).
+
+ Transform is applied via [prepareLayerTransformationMatrix] + canvas.concat, the
+ SAME matrix GraphicsLayerOwnerLayer uses for hit-testing (mapOffset), so draw and
+ hit-test provably agree. Shadow + rounded/shape clip go through the project canvas
+ interfaces (NativeShadowCanvas / NativeShapeClipCanvas), exactly as the old
+ ProjectOwnedLayer did.
+*/
+internal class DeferredRenderNode : NativeRenderNode {
+
+	override var topLeft: IntOffset = IntOffset.Zero
+	override var size: IntSize = IntSize.Zero
+	override var pivot: Offset = Offset.Unspecified
+	override var alpha: Float = 1f
+	override var scaleX: Float = 1f
+	override var scaleY: Float = 1f
+	override var translationX: Float = 0f
+	override var translationY: Float = 0f
+	override var rotationX: Float = 0f
+	override var rotationY: Float = 0f
+	override var rotationZ: Float = 0f
+	override var cameraDistance: Float = DefaultCameraDistance
+	override var shadowElevation: Float = 0f
+	override var ambientShadowColor: Color = Color.Black
+	override var spotShadowColor: Color = Color.Black
+	override var blendMode: BlendMode = BlendMode.SrcOver
+	override var colorFilter: ColorFilter? = null
+	override var renderEffect: RenderEffect? = null
+	override var compositingStrategy: CompositingStrategy = CompositingStrategy.Auto
+	override var clip: Boolean = false
+
+	// Outline pushed by GraphicsLayer.configureOutlineAndClip whenever clip OR a
+	// shadow is present — so it drives BOTH the content clip (when clip=true) and
+	// the drop-shadow silhouette (when shadowElevation>0, even with clip=false).
+	private var clipOutline: Outline? = null
+
+	override fun setClipRect(left: Float, top: Float, right: Float, bottom: Float) {
+		clipOutline = Outline.Rectangle(Rect(left, top, right, bottom))
+	}
+
+	override fun setClipRRect(left: Float, top: Float, right: Float, bottom: Float, radii: FloatArray) {
+		clipOutline = Outline.Rounded(
+			RoundRect(
+				left = left, top = top, right = right, bottom = bottom,
+				topLeftCornerRadius = CornerRadius(radii[0], radii[1]),
+				topRightCornerRadius = CornerRadius(radii[2], radii[3]),
+				bottomRightCornerRadius = CornerRadius(radii[4], radii[5]),
+				bottomLeftCornerRadius = CornerRadius(radii[6], radii[7]),
+			),
+		)
+	}
+
+	override fun setClipPath(path: Path?) {
+		clipOutline = if (path == null) null else Outline.Generic(path)
+	}
+
+	// ============
+	//  Record — store the block (deferred; replayed in drawInto).
+
+	private var recordedBlock: (DrawScope.() -> Unit)? = null
+	private var recordedDensity: Density = Density(1f)
+	private var recordedLayoutDirection: LayoutDirection = LayoutDirection.Ltr
+	private val drawScope = CanvasDrawScope()
+
+	override fun record(
+		density: Density,
+		layoutDirection: LayoutDirection,
+		size: IntSize,
+		block: DrawScope.() -> Unit,
+	) {
+		recordedDensity = density
+		recordedLayoutDirection = layoutDirection
+		this.size = size
+		recordedBlock = block
+	}
+
+	override fun drawInto(canvas: Canvas) {
+		val block = recordedBlock ?: return
+		val w = size.width.toFloat()
+		val h = size.height.toFloat()
+
+		canvas.save()
+		canvas.translate(topLeft.x.toFloat(), topLeft.y.toFloat())
+
+		// Transform about the pivot (default centre) — via the SAME matrix used for
+		// hit-testing, so draw and hit-test agree.
+		val hasTransform = scaleX != 1f || scaleY != 1f || rotationZ != 0f ||
+			rotationX != 0f || rotationY != 0f || translationX != 0f || translationY != 0f
+		if (hasTransform && w > 0f && h > 0f) {
+			val pivotX = if (pivot.isUnspecified) w / 2f else pivot.x
+			val pivotY = if (pivot.isUnspecified) h / 2f else pivot.y
+			val matrix = Matrix()
+			prepareLayerTransformationMatrix(
+				matrix = matrix,
+				pivotX = pivotX, pivotY = pivotY,
+				translationX = translationX, translationY = translationY,
+				rotationX = rotationX, rotationY = rotationY, rotationZ = rotationZ,
+				scaleX = scaleX, scaleY = scaleY, cameraDistance = cameraDistance,
+			)
+			canvas.concat(matrix)
+		}
+
+		// Drop shadow — layer-local, BEFORE the clip (shadow lives outside bounds).
+		if (shadowElevation > 0f && w > 0f && h > 0f) {
+			val outline = clipOutline
+			if (outline != null) {
+				(canvas as? NativeShadowCanvas)
+					?.drawDropShadow(outline, shadowElevation, ambientShadowColor, spotShadowColor)
+			}
+		}
+
+		// Content clip.
+		if (clip && w > 0f && h > 0f) applyClip(canvas)
+
+		// Offscreen for alpha (behaviour-preserving: the old paths saveLayer'd on
+		// alpha<1). ModulateAlpha suppresses the offscreen (alpha folds per-op) — but
+		// our DrawScope has no per-op multiplier yet, so it still composites here.
+		val needsAlphaLayer = alpha < 1f && w > 0f && h > 0f
+		if (needsAlphaLayer) {
+			canvas.saveLayer(
+				Rect(0f, 0f, w, h),
+				Paint().apply { alpha = this@DeferredRenderNode.alpha },
+			)
+		}
+
+		drawScope.draw(recordedDensity, recordedLayoutDirection, canvas, Size(w, h), block)
+
+		if (needsAlphaLayer) canvas.restore()
+		canvas.restore()
+	}
+
+	private fun applyClip(canvas: Canvas) {
+		when (val outline = clipOutline) {
+			is Outline.Rectangle -> canvas.clipRect(
+				outline.rect.left, outline.rect.top, outline.rect.right, outline.rect.bottom,
+			)
+			is Outline.Rounded -> {
+				// Skia clips rounded natively via clipPath; the SDL canvas has no
+				// path-clip primitive, so it implements NativeShapeClipCanvas and clips
+				// the rounded outline via an offscreen mask (preferred over clipPath,
+				// which falls back to the bounding rect there and left rounded state
+				// layers looking square).
+				val shapeClip = canvas as? NativeShapeClipCanvas
+				if (shapeClip != null) {
+					shapeClip.clipRoundRect(outline.roundRect)
+				} else {
+					val path = Path().apply { addRoundRect(outline.roundRect) }
+					canvas.clipPath(path)
+				}
+			}
+			is Outline.Generic -> canvas.clipPath(outline.path)
+			null -> {}
+		}
+	}
+
+	override fun close() {
+		recordedBlock = null
+	}
+}

compose/ui/ui/src/sdlRendererMain/kotlin/com/compose/sdl/graphics/GraphicsContextFactory.sdl.kt

@@ -0,0 +1,11 @@
+package com.compose.sdl.graphics
+
+import androidx.compose.ui.graphics.GraphicsContext
+
+// ==================
+// MARK: createGraphicsContext — SDL3 renderer actual
+// ==================
+
+/* The SDL leg uses the project record/replay GraphicsContext (backed by the SDL
+   NativeRenderNode via createProjectGraphicsLayer). This is the permanent SDL home. */
+internal actual fun createGraphicsContext(): GraphicsContext = ProjectGraphicsContext()

compose/ui/ui/src/sdlRendererMain/kotlin/com/compose/sdl/graphics/GraphicsLayerFactory.native.kt

@@ -0,0 +1,14 @@
+package com.compose.sdl.graphics
+
+import androidx.compose.ui.graphics.layer.GraphicsLayer
+
+// ==================
+// MARK: GraphicsLayer factory — native actuals
+// ==================
+
+internal fun createProjectGraphicsLayer(): GraphicsLayer =
+	GraphicsLayer(createNativeRenderNode(NativeRenderNodeContext()))
+
+internal fun releaseProjectGraphicsLayer(inLayer: GraphicsLayer) {
+	inLayer.release()
+}

compose/ui/ui/src/sdlRendererMain/kotlin/com/compose/sdl/graphics/NativeRenderNode.kt

@@ -0,0 +1,105 @@
+package com.compose.sdl.graphics
+
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.graphics.BlendMode
+import androidx.compose.ui.graphics.Canvas
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.ColorFilter
+import androidx.compose.ui.graphics.Path
+import androidx.compose.ui.graphics.RenderEffect
+import androidx.compose.ui.graphics.drawscope.DrawScope
+import androidx.compose.ui.graphics.layer.CompositingStrategy
+import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.IntOffset
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.unit.LayoutDirection
+
+// ==================
+// MARK: NativeRenderNode — the renderer-agnostic retained display-list node
+// ==================
+
+/**
+ * The one genuinely renderer-specific piece of the retained-layer engine. This is
+ * the [GraphicsLayer] façade's backing node — the analogue of skiko's
+ * `org.jetbrains.skiko.node.RenderNode`. [GraphicsLayer] (our copy-edit of upstream
+ * `SkiaGraphicsLayer.skiko.kt`) mirrors every visual property onto this node, calls
+ * [record] to capture the layer's drawing once, and [drawInto] to replay it every
+ * frame with the transform / clip / shadow / compositing applied — WITHOUT
+ * re-recording.
+ *
+ * Property contract mirrors skiko `RenderNode` (translation/scale/rotation/pivot/
+ * alpha/shadow/clip/…), so the Skia actual wraps skiko `RenderNode` almost verbatim
+ * and the SDL actual (`SdlRenderNode`) implements the same contract.
+ *
+ * [record]/[drawInto] are higher-level than skiko's `beginRecording()`/`drawInto()`
+ * so BOTH a display-list impl (Skia: record into a skiko RenderNode; SDL later: a
+ * cached-geometry / offscreen display list) AND the current deferred-replay impl
+ * (SDL now: store the block, replay it under the transform) satisfy them.
+ */
+internal interface NativeRenderNode {
+
+	// ============
+	//  Geometry — where the recorded content sits and its transform origin.
+
+	var topLeft: IntOffset
+	var size: IntSize
+	var pivot: Offset
+
+	// ============
+	//  Transform — applied at replay, no re-record (matches skiko RenderNode).
+
+	var alpha: Float
+	var scaleX: Float
+	var scaleY: Float
+	var translationX: Float
+	var translationY: Float
+	var rotationX: Float
+	var rotationY: Float
+	var rotationZ: Float
+	var cameraDistance: Float
+
+	// ============
+	//  Elevation shadow.
+
+	var shadowElevation: Float
+	var ambientShadowColor: Color
+	var spotShadowColor: Color
+
+	// ============
+	//  Compositing — decides an offscreen (requiresLayer) and how content composites.
+
+	var blendMode: BlendMode
+	var colorFilter: ColorFilter?
+	var renderEffect: RenderEffect?
+	var compositingStrategy: CompositingStrategy
+
+	// ============
+	//  Clip — outline pushed onto the node; rect / rounded-rect / generic path.
+
+	var clip: Boolean
+	fun setClipRect(left: Float, top: Float, right: Float, bottom: Float)
+	fun setClipRRect(left: Float, top: Float, right: Float, bottom: Float, radii: FloatArray)
+	fun setClipPath(path: Path?)
+
+	// ============
+	//  Record / replay.
+
+	/** Capture the layer content once; re-called only when the layer is dirty. */
+	fun record(density: Density, layoutDirection: LayoutDirection, size: IntSize, block: DrawScope.() -> Unit)
+
+	/** Replay the recorded content onto [canvas], applying this node's transform. */
+	fun drawInto(canvas: Canvas)
+
+	/** Release native resources (textures / picture / display list). */
+	fun close()
+}
+
+/**
+ * Per-window context shared by the [NativeRenderNode]s of one composition — the
+ * analogue of skiko's `RenderNodeContext`. Minimal today; the SDL caching impl will
+ * grow it to carry the renderer handle it needs to allocate offscreen targets.
+ */
+internal class NativeRenderNodeContext(
+	val measureDrawBounds: Boolean = false,
+)
+

compose/ui/ui/src/sdlRendererMain/kotlin/com/compose/sdl/graphics/NativeRenderNode.sdl.kt

@@ -0,0 +1,37 @@
+package com.compose.sdl.graphics
+
+import com.compose.sdl.renderer.sdl.SdlDisplayListRenderNode
+import com.compose.sdl.renderer.sdl.SdlRenderNode
+import kotlinx.cinterop.ExperimentalForeignApi
+import kotlinx.cinterop.toKString
+
+// ==================
+// MARK: createNativeRenderNode — SDL3 renderer actual
+// ==================
+
+/* CDN_LAYERCACHE selects the retained node. The DEFAULT is now the cached-geometry
+   node (Phase 4): it records each leaf's tessellated geometry + plain text runs ONCE
+   and replays them under the layer transform — crisp/bit-exact at any transform, no
+   render-target state, deterministic. A full 57-screen geo-vs-block-replay sweep is
+   clean (55 at 0.000%; GraphicsLayer/ModShortcuts <0.13% cosmetic rotated-edge AA)
+   and the former Carousel/Pickers diffs are gone, so it graduates from opt-in to
+   default. See RENDERER.md §4b/§13.
+
+   Escape hatches (env override):
+     off / defer / 0  → DeferredRenderNode  (replay the block every frame; no caching —
+                                             the previous default, kept as a fallback)
+     1 / texture      → SdlRenderNode       (offscreen-texture cache — legacy; fast for
+                                             static leaves but timing-nondeterministic
+                                             on complex screens, so not the default)
+     *                → SdlDisplayListRenderNode (geo — the default) */
+@OptIn(ExperimentalForeignApi::class)
+private val layerCacheMode: String by lazy {
+	platform.posix.getenv("CDN_LAYERCACHE")?.toKString() ?: ""
+}
+
+internal fun createNativeRenderNode(context: NativeRenderNodeContext): NativeRenderNode =
+	when (layerCacheMode) {
+		"off", "defer", "0" -> DeferredRenderNode()
+		"1", "texture" -> SdlRenderNode()
+		else -> SdlDisplayListRenderNode()
+	}

compose/ui/ui/src/sdlRendererMain/kotlin/com/compose/sdl/graphics/ProjectGraphicsContext.kt

@@ -0,0 +1,18 @@
+package com.compose.sdl.graphics
+
+import androidx.compose.ui.graphics.GraphicsContext
+import androidx.compose.ui.graphics.layer.GraphicsLayer
+
+// ==================
+// MARK: ProjectGraphicsContext — SDL leg (record/replay GraphicsLayer)
+// ==================
+
+/* The SDL leg's GraphicsContext: creates/releases the project record/replay
+   GraphicsLayer (backed by the SDL NativeRenderNode). GraphicsLayer's `expect class`
+   hides its constructor/release from common code, so layer creation/release hop
+   through the [createProjectGraphicsLayer] / [releaseProjectGraphicsLayer] factories
+   (co-located here). `shadowContext` keeps the GraphicsContext interface default. */
+internal class ProjectGraphicsContext : GraphicsContext {
+	override fun createGraphicsLayer(): GraphicsLayer = createProjectGraphicsLayer()
+	override fun releaseGraphicsLayer(layer: GraphicsLayer) = releaseProjectGraphicsLayer(layer)
+}

compose/ui/ui/src/sdlRendererMain/kotlin/com/compose/sdl/renderer/sdl/Sdl3Canvas.kt

@@ -20,6 +20,7 @@ import androidx.compose.ui.graphics.BlendMode
 import androidx.compose.ui.graphics.drawscope.DrawStyle
 import androidx.compose.ui.graphics.drawscope.Fill
 import androidx.compose.ui.graphics.drawscope.Stroke
+import com.compose.sdl.graphics.a8
 import com.compose.sdl.graphics.b8
 import com.compose.sdl.graphics.g8
 import com.compose.sdl.graphics.r8
@@ -71,17 +72,87 @@ internal class Sdl3Canvas(
 	// Alpha8 mask) so the tint applied on blit colours it correctly.
 	private val fOffscreenTexture: COpaquePointer? = null,
 	private val fForceWhite: Boolean = false,
+	// Phase 4 capture mode: when set, this canvas RECORDS shape geometry into the list
+	// (via the scope's recordingSink) and touches NO GPU. Ops not yet capturable
+	// (text / image / clip / saveLayer / shadow) mark the list `unsupported` so the
+	// SdlDisplayListRenderNode falls back to a crisp block-replay for that leaf — so
+	// no un-captured op ever leaks to the screen. See SdlDisplayList.
+	private val fCaptureList: SdlDisplayList? = null,
 ) : Canvas,
 	com.compose.sdl.text.NativeTextCanvas,
 	com.compose.sdl.graphics.NativePainterCanvas,
 	com.compose.sdl.graphics.NativeShapeClipCanvas,
-	com.compose.sdl.graphics.NativeShadowCanvas {
+	com.compose.sdl.graphics.NativeShadowCanvas,
+	com.compose.sdl.graphics.NativeFinishableCanvas {
 
 	// The tessellating scope. It emits geometry in the canvas's user space; the
 	// canvas hands it the current affine each draw (setMatrix) so scale / rotate /
 	// translate reach the vertices.
 	private val fScope = Sdl3DrawScope(fRenderer, 0f, 0f, fSize)
 
+	init {
+		// Capture mode routes the scope's geometry to the display list instead of the GPU.
+		if (fCaptureList != null) fScope.recordingSink = fCaptureList
+	}
+
+	// Capture-mode gate for ops we can't record yet: flag the list unsupported (the
+	// node will replay the block instead) and skip the GPU work. Returns true if the
+	// caller should return early. No-op (false) outside capture mode.
+	private fun captureUnsupported(): Boolean {
+		val list = fCaptureList ?: return false
+		list.unsupported = true
+		return true
+	}
+
+	// Replay a captured display list into this (real) canvas under its CURRENT
+	// transform, in order (z-order preserved). Geometry batches re-emit their
+	// layer-local vertices through the affine; text runs flush pending geometry then
+	// re-look-up + blit at the transformed origin (glyph size stays logical). Used by
+	// SdlDisplayListRenderNode.drawInto.
+	internal fun replayDisplayList(list: SdlDisplayList) {
+		fScope.flush()
+		fScope.setMatrix(fMa, fMb, fMc, fMd, fMe, fMf)
+		for (i in list.commands.indices) {
+			when (val cmd = list.commands[i]) {
+				is GeometryBatch -> fScope.replayBatch(cmd.vertexData, cmd.vertexCount)
+				is TextRun -> {
+					fScope.flush() // submit geometry before this run (z-order)
+					// Transform the run ORIGIN by the affine; keep glyph size logical
+					// (matches the immediate path: layer scale reaches position, not size).
+					fTextRenderer?.blitRun(
+						inFontFamily = cmd.fontFamily,
+						inText = cmd.text,
+						inFontSize = cmd.fontSizePx,
+						inFontVariations = cmd.variations,
+						inStyle = cmd.style,
+						inDeviceX = mapX(cmd.x, cmd.y),
+						inDeviceY = mapY(cmd.x, cmd.y),
+						inLogW = cmd.w,
+						inLogH = cmd.h,
+						inColor = androidx.compose.ui.graphics.Color(cmd.colorArgb),
+					)
+				}
+				is IconRun -> {
+					fScope.flush() // submit geometry before this glyph (z-order)
+					// Map the box origin through the affine; box size stays logical (the
+					// glyph centres in it — layer scale reaches position, not glyph size).
+					fTextRenderer?.blitIconRun(
+						inFontFamily = cmd.fontFamily,
+						inText = cmd.text,
+						inFontSize = cmd.fontSizePx,
+						inFontVariations = cmd.variations,
+						inDeviceBoxX = mapX(cmd.boxX, cmd.boxY),
+						inDeviceBoxY = mapY(cmd.boxX, cmd.boxY),
+						inBoxW = cmd.boxW,
+						inBoxH = cmd.boxH,
+						inColor = androidx.compose.ui.graphics.Color(cmd.colorArgb),
+					)
+				}
+			}
+		}
+		fScope.flush()
+	}
+
 	// Current user→screen affine (a,b,c,d,e,f): screen = (a*x+c*y+e, b*x+d*y+f).
 	// Accumulates Canvas.translate/scale/rotate/concat; identity + a translate is
 	// the common layout-positioning case.
@@ -279,7 +350,7 @@ internal class Sdl3Canvas(
 
 	// Flushes any pending batched geometry to SDL, then frees the scope's
 	// native buffer + clears the SDL clip. Call once per frame after the draw.
-	fun finish() {
+	override fun finish() {
 		fPendingClips.clear()
 		fScope.release()
 		// Safety: an unbalanced save/restore must never leave the renderer pointed
@@ -343,6 +414,14 @@ internal class Sdl3Canvas(
 		val vRenderer = fRenderer.reinterpret<cnames.structs.SDL_Renderer>()
 		fSavedOffscreenTarget = SDL_GetRenderTarget(vRenderer)
 		SDL_SetRenderTarget(vRenderer, vTex.reinterpret())
+		// Clear to transparent. Render-target textures aren't auto-cleared, and a
+		// retained-layer texture (SdlRenderNode) is REUSED across re-records — without
+		// this, a re-record ghosts the previous content, which showed up as multi-frame
+		// instability on churny screens (Pickers). Fresh textures happen to be zeroed
+		// so static leaves were fine, but reuse needs an explicit clear. RenderClear
+		// fills with the draw colour ignoring blend, so (0,0,0,0) = transparent.
+		SDL_SetRenderDrawColor(vRenderer, 0u, 0u, 0u, 0u)
+		SDL_RenderClear(vRenderer)
 		fClip = null
 		SDL_SetRenderClipRect(vRenderer, null)
 	}
@@ -355,6 +434,7 @@ internal class Sdl3Canvas(
 	}
 
 	override fun saveLayer(bounds: Rect, paint: Paint) {
+		if (captureUnsupported()) return
 		// No real offscreen buffer — SDL3 lacks a portable render-target-in-a-batched-scope
 		// primitive here. Instead, multiplicatively propagate the layer's alpha through
 		// every enclosed primitive: each draw() reads `fAlpha` and multiplies against
@@ -386,6 +466,7 @@ internal class Sdl3Canvas(
 	}
 
 	override fun clipRect(left: Float, top: Float, right: Float, bottom: Float, clipOp: ClipOp) {
+		if (captureUnsupported()) return
 		if (clipOp == ClipOp.Difference) {
 			clipRectDifference(left, top, right, bottom)
 			return
@@ -426,6 +507,7 @@ internal class Sdl3Canvas(
 	}
 
 	override fun clipPath(path: ComposePath, clipOp: ClipOp) {
+		if (captureUnsupported()) return
 		// SDL has only rectangular render clipping; approximate a path clip by
 		// its bounding box (TODO: stencil/mask for non-rect clips).
 		val vB = pathBounds(path) ?: return
@@ -466,6 +548,7 @@ internal class Sdl3Canvas(
 	//  arbitrary paths keep the clipPath bbox fallback.
 
 	override fun clipRoundRect(inRoundRect: RoundRect) {
+		if (captureUnsupported()) return
 		// The mask is cut in DEVICE space (the bbox below goes through the
 		// affine), but the corner radii arrive in LOCAL user space — scale
 		// them by the affine too, or a graphicsLayer-scaled circle clip cuts
@@ -705,6 +788,7 @@ internal class Sdl3Canvas(
 		inAmbientColor: androidx.compose.ui.graphics.Color,
 		inSpotColor: androidx.compose.ui.graphics.Color,
 	) {
+		if (captureUnsupported()) return
 		realizePendingClips()
 		if (inElevationPx <= 0f) return
 
@@ -958,7 +1042,26 @@ internal class Sdl3Canvas(
 		inFontVariations: List<androidx.compose.ui.text.font.FontVariation.Setting>?,
 		inBaseItalic: Boolean,
 		inTextDecoration: androidx.compose.ui.text.style.TextDecoration?,
+		inLineHeightPx: Float,
+		inTrimFirstLine: Boolean,
 	) {
+		// Capture mode: icon-font glyphs (Material Symbols via FreeType) record as an
+		// IconRun — flush pending geometry first for z-order, then capture the box in
+		// LAYER-LOCAL device coords (replay maps it through the layer affine + re-draws
+		// via FreeTypeIcons' cache). Plain/decorated AND spanned text ARE captured too
+		// (runSink set below; each styled run becomes a TextRun) — only a run with a
+		// SpanStyle.background still bails inside Sdl3TextRenderer.drawText.
+		val vCaptureList = fCaptureList
+		if (vCaptureList != null && inFontFamily != null && IconFont.isIconFamily(inFontFamily)) {
+			fScope.flush()
+			val vIconColor = if (fAlpha >= 1f) inColor else inColor.copy(alpha = inColor.alpha * fAlpha)
+			val vArgb = (vIconColor.a8 shl 24) or (vIconColor.r8 shl 16) or (vIconColor.g8 shl 8) or vIconColor.b8
+			vCaptureList.captureIconRun(
+				inFontFamily, inText, inFontSizePx, inFontVariations,
+				mapX(inX, inY), mapY(inX, inY), inBoxWidth, inBoxHeight, vArgb,
+			)
+			return
+		}
 		// Small centred labels (a popped bubble's "pop") usually sit fully
 		// inside a rounded clip — gate on containment like other draws, with
 		// a 2px margin for glyph overhang / AA bleed, instead of paying a
@@ -1016,21 +1119,38 @@ internal class Sdl3Canvas(
 		// right edge instead of wrapping when the sidebar was resized narrower.
 		val vWrapWidth = if (inSoftWrap && inBoxWidth > 0f) inBoxWidth.toInt() else Int.MAX_VALUE
 		val vWrapped = vRenderer.wrap(inText, inFontSizePx, vWrapWidth, inFontFamily, inFontVariations)
-		val vBaseLineH = vRenderer.lineHeight(inFontSizePx, inFontFamily, inFontVariations)
+		// Line stacking mirrors SdlParagraph's per-mode model: compat trim (raw styles)
+		// keeps the FIRST line at the tight font cell; M3's Trim.None (inTrimFirstLine =
+		// false) makes every line the full band. Following lines always advance by the
+		// band (inLineHeightPx) when supplied, else the font cell.
+		val vFontCellH = vRenderer.lineHeight(inFontSizePx, inFontFamily, inFontVariations)
+		val vAdvance = if (inLineHeightPx > 0f) inLineHeightPx else vFontCellH
+		val vFirstLineH = if (inTrimFirstLine || inLineHeightPx <= 0f) vFontCellH else vAdvance
 		// Per-run fontSize spans make a line's box the TALLEST run cell on it —
 		// same styledLineCellHeight the paragraph measured with, so paint stacks
 		// lines exactly where layout put them.
 		val vMetricSpans = com.compose.sdl.text.spansAffectMetrics(inSpans)
 
+		// Capture mode: route each plain line's run to the display list (spanned lines
+		// bail inside drawText via markUnsupported). Reset after the loop. No-op when
+		// not capturing (vCaptureList == null).
+		fTextRenderer?.runSink = vCaptureList
+
 		var vLineY = inY
 		for ((vIdx, vLine) in vWrapped.lines.withIndex()) {
 			val vLineH =
 				if (vMetricSpans && inSpans != null) {
-					com.compose.sdl.text.styledLineCellHeight(
-						vLine, vWrapped.lineStarts.getOrElse(vIdx) { 0 }, inSpans,
-						inFontSizePx, vTr.dpr, vRenderer, inFontFamily, inFontVariations,
+					// Size spans can exceed the band, never shrink below it — the same
+					// max() the paragraph's lineHeights used, so paint tracks layout
+					// (first line keeps its tight cell under compat trim).
+					kotlin.math.max(
+						com.compose.sdl.text.styledLineCellHeight(
+							vLine, vWrapped.lineStarts.getOrElse(vIdx) { 0 }, inSpans,
+							inFontSizePx, vTr.dpr, vRenderer, inFontFamily, inFontVariations,
+						),
+						if ((vIdx == 0 && inTrimFirstLine) || inLineHeightPx <= 0f) 0f else inLineHeightPx,
 					)
-				} else vBaseLineH
+				} else if (vIdx == 0) vFirstLineH else vAdvance
 			// Cull lines that would fall entirely below the box (softWrap keeps the
 			// natural line count; the box just clips at draw time).
 			if (vLineY >= inY + inBoxHeight) break
@@ -1056,6 +1176,7 @@ internal class Sdl3Canvas(
 			)
 			vLineY += vLineH
 		}
+		fTextRenderer?.runSink = null
 	}
 
 	// ============
@@ -1072,6 +1193,7 @@ internal class Sdl3Canvas(
 		inContentScale: androidx.compose.ui.layout.ContentScale,
 		inAlpha: Float,
 	) {
+		if (captureUnsupported()) return
 		admitDraw(inX, inY, inX + inWidth, inY + inHeight)
 		fScope.flush()
 		// Map the origin through the affine and scale the size by the matrix's axis
@@ -1090,6 +1212,7 @@ internal class Sdl3Canvas(
 	//  Not-yet-wired ops (B5 image leaf / B6 layers). Accept-and-ignore.
 
 	override fun drawImage(image: ImageBitmap, topLeftOffset: Offset, paint: Paint) {
+		if (captureUnsupported()) return
 		val vBmp = image as? SdlImageBitmap ?: return
 		admitDraw(topLeftOffset.x, topLeftOffset.y, topLeftOffset.x + vBmp.width, topLeftOffset.y + vBmp.height)
 		drawImageRect(
@@ -1114,6 +1237,7 @@ internal class Sdl3Canvas(
 		dstSize: androidx.compose.ui.unit.IntSize,
 		paint: Paint,
 	) {
+		if (captureUnsupported()) return
 		realizePendingClips()
 		val vTex = (image as? SdlImageBitmap)?.texture ?: return
 		com.compose.sdl.graphics.DrawStats.imageBlits++

compose/ui/ui/src/sdlRendererMain/kotlin/com/compose/sdl/renderer/sdl/Sdl3DrawScope.kt

@@ -112,6 +112,14 @@ internal class Sdl3DrawScope(
 	internal fun setMatrix(a: Float, b: Float, c: Float, d: Float, e: Float, f: Float) {
 		fMa = a; fMb = b; fMc = c; fMd = d; fMe = e; fMf = f
 	}
+	// Current device affine (a,b,c,d,e,f) — screen = (a*x+c*y+e, b*x+d*y+f). Phase 4
+	// replay reads this to re-transform captured layer-local vertices.
+	internal fun currentDeviceMatrix(): FloatArray = floatArrayOf(fMa, fMb, fMc, fMd, fMe, fMf)
+
+	// Phase 4: when set, flush() CAPTURES the tessellated batch (layer-local, if this
+	// scope's base CTM is identity) instead of submitting to the GPU. null = normal
+	// immediate submit. See SdlDisplayList.
+	internal var recordingSink: GeometrySink? = null
 
 	// ============
 	//  Vertex batch — heap-allocated buffer of SDL_Vertex shared across
@@ -133,6 +141,13 @@ internal class Sdl3DrawScope(
 	   call mid-scope when the buffer fills up (no cross-triangle state). */
 	fun flush() {
 		if (fBatchCount == 0) return
+		val vSink = recordingSink
+		if (vSink != null) {
+			// Phase 4 recording: capture the batch (layer-local) instead of submitting.
+			vSink.captureGeometry(fVertexData, fBatchCount)
+			fBatchCount = 0
+			return
+		}
 		fVertexData.usePinned { vPinned ->
 			platform.posix.memcpy(
 				fBatch,
@@ -932,6 +947,28 @@ internal class Sdl3DrawScope(
 		emitFringeQuad(x0, y0, x1, y1, x1 + inNx, y1 + inNy, x0 + inNx, y0 + inNy, inSampler)
 	}
 
+	// Phase 4 replay: re-emit a captured (layer-local) batch through the CURRENT CTM.
+	// The batch was recorded with an identity base CTM, so applying fMa..fMf here
+	// places it at the layer's transform. Colours/UVs pass through unchanged. Runs
+	// in NORMAL (non-recording) mode → the next flush() submits via SDL_RenderGeometry.
+	internal fun replayBatch(vd: FloatArray, count: Int) {
+		for (i in 0 until count) {
+			if (fBatchCount >= kBatchCapacity && fBatchCount % 3 == 0) flush()
+			val s = i * kFloatsPerVertex
+			val x = vd[s]; val y = vd[s + 1]
+			val base = fBatchCount * kFloatsPerVertex
+			fVertexData[base + 0] = fMa * x + fMc * y + fMe
+			fVertexData[base + 1] = fMb * x + fMd * y + fMf
+			fVertexData[base + 2] = vd[s + 2]
+			fVertexData[base + 3] = vd[s + 3]
+			fVertexData[base + 4] = vd[s + 4]
+			fVertexData[base + 5] = vd[s + 5]
+			fVertexData[base + 6] = vd[s + 6]
+			fVertexData[base + 7] = vd[s + 7]
+			fBatchCount++
+		}
+	}
+
 	// Stage one vertex into fVertexData (auto-flush when full). Position goes
 	// through the current affine so scale/rotate reach the GPU; the colour is
 	// sampled at the pre-transform point so a gradient rides its shape.
@@ -973,7 +1010,7 @@ private const val kBatchCapacity: Int = 8190
 
 // Floats per SDL_Vertex: position(x,y) + color(r,g,b,a) + tex_coord(x,y), tightly
 // packed. Used to stage vertices in a Kotlin FloatArray and memcpy them across.
-private const val kFloatsPerVertex: Int = 8
+internal const val kFloatsPerVertex: Int = 8
 
 // ==================
 // MARK: Brush → per-vertex colour sampler

compose/ui/ui/src/sdlRendererMain/kotlin/com/compose/sdl/renderer/sdl/Sdl3Offscreen.kt

@@ -157,6 +157,12 @@ internal class Sdl3OffscreenRenderer(
 			fForceWhite = vBmp.config == ImageBitmapConfig.Alpha8,
 		)
 	}
+
+	// Phase 4: a capture canvas records shape geometry into [list] and touches NO GPU
+	// (text/image/clip mark the list unsupported). Used by SdlDisplayListRenderNode to
+	// record a leaf's layer-local geometry. No render target — no timing nondeterminism.
+	internal fun createCaptureCanvas(list: SdlDisplayList, size: Size): Sdl3Canvas =
+		Sdl3Canvas(fRenderer, size, fTextRenderer, fCaptureList = list)
 }
 
 // ==================

compose/ui/ui/src/sdlRendererMain/kotlin/com/compose/sdl/renderer/sdl/Sdl3RenderBackend.kt

@@ -88,7 +88,7 @@ internal class Sdl3RenderBackend(private val backend: SDL3Backend) : RenderBacke
     // Paint the upstream LayoutNode tree through the vendored pipeline.
     // inHost.rootNode.draw → NodeCoordinator.draw → DrawModifierNode → CanvasDrawScope
     // → Sdl3Canvas → SDL_RenderGeometry.
-    override fun drawRoot(inHost: com.compose.sdl.node.ComposeRootHost) {
+    override fun drawRoot(inDraw: (androidx.compose.ui.graphics.Canvas) -> Unit) {
         val vRenderer = backend.renderer ?: return
         val vClipTargets = fClipTargets ?: Sdl3ClipTargets(vRenderer).also { fClipTargets = it }
         val vShadowCache = fShadowCache ?: Sdl3ShadowCache(vRenderer).also { fShadowCache = it }
@@ -108,7 +108,7 @@ internal class Sdl3RenderBackend(private val backend: SDL3Backend) : RenderBacke
         // Expose the frame canvas so an offscreen render can flush it before borrowing
         // the render target (z-order).
         currentMainCanvas = vCanvas
-        inHost.rootNode.draw(vCanvas, null)
+        inDraw(vCanvas)
         vCanvas.finish()
         currentMainCanvas = null
     }

compose/ui/ui/src/sdlRendererMain/kotlin/com/compose/sdl/renderer/sdl/Sdl3TextRenderer.kt

@@ -53,6 +53,13 @@ import sdl3_ttf.TTF_StringToTag
 import sdl3.SDL_IOFromConstMem
 import androidx.compose.ui.text.font.FontVariation
 import androidx.compose.ui.unit.Density
+import freetype.FT_Done_Face
+import freetype.FT_Done_FreeType
+import freetype.FT_FaceVar
+import freetype.FT_Init_FreeType
+import freetype.FT_Library
+import freetype.FT_LibraryVar
+import freetype.FT_New_Memory_Face
 
 // ==================
 // MARK: Sdl3TextRenderer (mingwX64 fallback)
@@ -176,6 +183,11 @@ internal class Sdl3TextRenderer(private val backend: SDL3Backend) {
     // Cap-and-clear (not LRU): lookups stay a single hash op on the hot measure
     // path, and re-measuring after a rare full clear is cheap.
     private data class WidthKey(val family: String?, val text: String, val fontSize: Int, val variations: String, val style: Int)
+    // Phase 4: when set, drawText CAPTURES a plain run (text + params) into the display
+    // list instead of blitting — eviction-safe (replay re-looks-up the cache). Set only
+    // for plain (no-span) text by Sdl3Canvas capture mode; spanned/icon text bails.
+    internal var runSink: TextRunSink? = null
+
     private val fWidthCache = mutableMapOf<WidthKey, Int>()
 
     /* Returns false if TTF couldn't init. */
@@ -194,6 +206,9 @@ internal class Sdl3TextRenderer(private val backend: SDL3Backend) {
         for ((vMem, _) in fFontMem.values) nativeHeap.free(vMem)
         fFontMem.clear()
         fMissingFamilies.clear()
+        fCellRatios.clear()
+        fMetricsLib?.let { FT_Done_FreeType(it) }
+        fMetricsLib = null
         fFreeTypeIcons.destroy()
         TTF_Quit()
     }
@@ -214,12 +229,66 @@ internal class Sdl3TextRenderer(private val backend: SDL3Backend) {
 
         override fun lineHeight(inFontSize: Int, inFontFamily: String?, inFontVariations: List<androidx.compose.ui.text.font.FontVariation.Setting>?): Float {
             val vFont = getFont(inFontFamily, inFontSize, inFontVariations) ?: return inFontSize * 1.3f
+            // Skia-aligned cell for TEXT fonts (P3.1): Skia scales the face's hhea
+            // metrics linearly and the paragraph rounds to nearest, while
+            // TTF_GetFontHeight reports the grid-fitted CEILED int — +1px at the M3
+            // body sizes (12, 14), accumulating ~1px per stacked label down every
+            // parity page. Icon families keep the TTF value: their glyph boxes were
+            // tuned against it and Skia never renders them.
+            if (inFontFamily == null || !IconFont.isIconFamily(inFontFamily)) {
+                cellRatios(inFontFamily)?.let { vRatios ->
+                    val vPhysical = (inFontSize * fDpr).coerceAtLeast(1f)
+                    return (kotlin.math.round(vRatios.cell * vPhysical) / fDpr).coerceAtLeast(1f)
+                }
+            }
             // TTF_GetFontHeight returns physical pixels (we opened the
             // font at fontSize * DPR). Convert back to logical.
             return (TTF_GetFontHeight(vFont.reinterpret()).toFloat() / fDpr).coerceAtLeast(1f)
         }
     }
 
+    // ============
+    //  Unrounded face metrics (P3.1) — read hhea ascender/descender/upem once per
+    //  family straight from the font bytes via a metrics-only FreeType library
+    //  (SDL3_ttf exposes only grid-fitted ints). Ratios are size-independent.
+    private var fMetricsLib: FT_Library? = null
+    private data class CellRatios(val cell: Float, val ascent: Float)
+    private val fCellRatios = mutableMapOf<String?, CellRatios?>()
+
+    private fun cellRatios(inFamily: String?): CellRatios? {
+        if (fCellRatios.containsKey(inFamily)) return fCellRatios[inFamily]
+        val vComputed = computeCellRatios(inFamily)
+        fCellRatios[inFamily] = vComputed
+        return vComputed
+    }
+
+    private fun computeCellRatios(inFamily: String?): CellRatios? {
+        // getFont() has already staged the family bytes into fFontMem (lineHeight
+        // calls it first); absent bytes = system-font fallback -> no ratios.
+        val vSlot = fFontMem[inFamily] ?: return null
+        if (fMetricsLib == null) {
+            memScoped {
+                val vLibPtr = alloc<FT_LibraryVar>()
+                if (FT_Init_FreeType(vLibPtr.ptr).toInt() == 0) fMetricsLib = vLibPtr.value
+            }
+        }
+        val vLib = fMetricsLib ?: return null
+        memScoped {
+            val vFacePtr = alloc<FT_FaceVar>()
+            val vErr = FT_New_Memory_Face(vLib, vSlot.first.reinterpret(), vSlot.second.convert(), 0, vFacePtr.ptr)
+            if (vErr.toInt() != 0 || vFacePtr.value == null) return null
+            val vFace = vFacePtr.value!!.pointed
+            val vUpem = vFace.units_per_EM.toFloat()
+            val vRatios =
+                if (vUpem > 0f) CellRatios(
+                    cell = (vFace.ascender - vFace.descender).toFloat() / vUpem,
+                    ascent = vFace.ascender.toFloat() / vUpem,
+                ) else null
+            FT_Done_Face(vFacePtr.value)
+            return vRatios
+        }
+    }
+
     /* Greedy soft-wrap that mirrors the Skia renderer's algorithm so the
        cross-platform behaviour stays identical. Hard lines on '\n'; long
        lines split at whitespace, ultra-long words split mid-word. */
@@ -422,6 +491,11 @@ internal class Sdl3TextRenderer(private val backend: SDL3Backend) {
         // blit each as its own texture at its prefix x. Tabs expand for both the
         // prefix measure and the texture so offsets and glyphs agree.
         if (inSpans != null) {
+            // Capture mode: record each styled run as its own TextRun command (like the
+            // plain path) — replay re-looks-up the per-run segment texture, eviction-safe.
+            // A run wanting a SpanStyle.background bails to block-replay (the background
+            // fill isn't a captured command yet); rare — highlight/selection spans.
+            val vCapture = runSink
             // O(spans + line length) style runs (colour + weight + italic +
             // background + decoration + size), instead of an O(chars × spans)
             // per-character scan.
@@ -441,6 +515,16 @@ internal class Sdl3TextRenderer(private val backend: SDL3Backend) {
                 (if (inRun.italic) kStyleItalic else 0) or
                 (if (inRun.underline) kStyleUnderline else 0) or
                 (if (inRun.lineThrough) kStyleStrikethrough else 0)
+            // Background fills aren't a captured command yet — defer the whole leaf if
+            // any run wants one (rare: highlight/selection spans). Also keeps the
+            // background SDL_RenderFillRect below from firing during a capture pass.
+            if (vCapture != null) {
+                for (vRun in vRuns) {
+                    if (vRun.background != ComposeColor.Unspecified && vRun.background.alpha > 0f) {
+                        vCapture.markUnsupported(); return
+                    }
+                }
+            }
             // Line width = sum of each run's width at ITS style (for alignment).
             var vLineW = 0f
             for (vRun in vRuns) vLineW += measureWidth(runSeg(vRun), runPx(vRun), inFontFamily, runVars(vRun), runStyle(vRun)).toFloat()
@@ -499,17 +583,27 @@ internal class Sdl3TextRenderer(private val backend: SDL3Backend) {
                 }
                 val vCachedSeg = getOrCreateTexture(inFontFamily, vSeg, vPx, vVars, vStyle)
                 if (vCachedSeg != null) {
-                    applyTint(vCachedSeg.tex, vRun.color)
                     val vLogW = vCachedSeg.w / fDpr
                     val vLogH = vCachedSeg.h / fDpr
                     val vPenY = vBaselineY - fontAscent(vPx, inFontFamily, vVars)
-                    memScoped {
-                        val vDst = alloc<SDL_FRect>()
-                        vDst.x = snap(vRunX)
-                        vDst.y = snap(vPenY)
-                        vDst.w = vLogW
-                        vDst.h = vLogH
-                        SDL_RenderTexture(vRenderer.reinterpret(), vCachedSeg.tex.reinterpret(), null, vDst.ptr)
+                    if (vCapture != null) {
+                        // Record params (not the texture pointer) — eviction-safe replay.
+                        val vArgb = (vRun.color.a8 shl 24) or (vRun.color.r8 shl 16) or
+                            (vRun.color.g8 shl 8) or vRun.color.b8
+                        vCapture.captureTextRun(
+                            inFontFamily, vSeg, vPx, vVars, vStyle,
+                            snap(vRunX), snap(vPenY), vLogW, vLogH, vArgb,
+                        )
+                    } else {
+                        applyTint(vCachedSeg.tex, vRun.color)
+                        memScoped {
+                            val vDst = alloc<SDL_FRect>()
+                            vDst.x = snap(vRunX)
+                            vDst.y = snap(vPenY)
+                            vDst.w = vLogW
+                            vDst.h = vLogH
+                            SDL_RenderTexture(vRenderer.reinterpret(), vCachedSeg.tex.reinterpret(), null, vDst.ptr)
+                        }
                     }
                 }
                 vRunX += vAdvance
@@ -544,6 +638,18 @@ internal class Sdl3TextRenderer(private val backend: SDL3Backend) {
         // round(v * dpr) / dpr keeps the blit 1:1, matching Skia's crispness.
         fun snap(inV: Float): Float = kotlin.math.round(inV * fDpr) / fDpr
 
+        val vSink = runSink
+        if (vSink != null) {
+            // Capture the plain run for eviction-safe retained replay — params, NOT the
+            // texture pointer (the LRU may evict it; replay re-looks-up). Snapped
+            // layer-local dst; replay maps the origin through the layer affine.
+            val vArgb = (inColor.a8 shl 24) or (inColor.r8 shl 16) or (inColor.g8 shl 8) or inColor.b8
+            vSink.captureTextRun(
+                inFontFamily, vText, inFontSize, inFontVariations, vBaseStyle,
+                snap(vPenX), snap(vPenY), vLogW, vLogH, vArgb,
+            )
+            return
+        }
         memScoped {
             val vDst = alloc<SDL_FRect>()
             vDst.x = snap(vPenX)
@@ -554,6 +660,81 @@ internal class Sdl3TextRenderer(private val backend: SDL3Backend) {
         }
     }
 
+    // Phase 4 replay: blit a captured plain run. Re-looks-up the run texture
+    // (eviction-safe — re-rasterises if the LRU dropped it), applies the tint, and
+    // blits at the given DEVICE origin (already mapped through the layer affine) at
+    // logical size (matching the immediate path: layer scale reaches position, not size).
+    internal fun blitRun(
+        inFontFamily: String?,
+        inText: String,
+        inFontSize: Int,
+        inFontVariations: List<FontVariation.Setting>?,
+        inStyle: Int,
+        inDeviceX: Float,
+        inDeviceY: Float,
+        inLogW: Float,
+        inLogH: Float,
+        inColor: ComposeColor,
+    ) {
+        val vRenderer = backend.renderer ?: return
+        val vCached = getOrCreateTexture(inFontFamily, inText, inFontSize, inFontVariations, inStyle) ?: return
+        applyTint(vCached.tex, inColor)
+        memScoped {
+            val vDst = alloc<SDL_FRect>()
+            vDst.x = kotlin.math.round(inDeviceX * fDpr) / fDpr
+            vDst.y = kotlin.math.round(inDeviceY * fDpr) / fDpr
+            vDst.w = inLogW
+            vDst.h = inLogH
+            SDL_RenderTexture(vRenderer.reinterpret(), vCached.tex.reinterpret(), null, vDst.ptr)
+        }
+    }
+
+    /* Phase 4 replay: re-draw a captured icon glyph. Mirrors drawNativeText's icon
+       branch — FreeType glyph first (its own cache re-rasterises on eviction), then the
+       SDL_ttf fallback for a codepoint the FreeType path can't draw (rare: a glyph
+       absent from the subset font). Box origin is DEVICE (already mapped through the
+       layer affine); the glyph centres in the logical box. */
+    internal fun blitIconRun(
+        inFontFamily: String,
+        inText: String,
+        inFontSize: Int,
+        inFontVariations: List<FontVariation.Setting>?,
+        inDeviceBoxX: Float,
+        inDeviceBoxY: Float,
+        inBoxW: Float,
+        inBoxH: Float,
+        inColor: ComposeColor,
+    ) {
+        val vRenderer = backend.renderer ?: return
+        val vDrew = fFreeTypeIcons.drawGlyph(
+            inSdlRenderer = vRenderer,
+            inFamily = inFontFamily,
+            inCodepoint = inText.codePointAtSafe(0),
+            inPixelSize = inFontSize,
+            inColor = inColor,
+            inVariations = inFontVariations ?: emptyList(),
+            inBoxX = inDeviceBoxX.toInt(),
+            inBoxY = inDeviceBoxY.toInt(),
+            inBoxW = inBoxW.toInt(),
+            inBoxH = inBoxH.toInt(),
+            inDpr = fDpr,
+        )
+        if (vDrew) return
+        // SDL_ttf fallback — render the codepoint as a normal glyph, centred in the box.
+        val vCached = getOrCreateTexture(inFontFamily, inText, inFontSize, inFontVariations, 0) ?: return
+        applyTint(vCached.tex, inColor)
+        val vLogW = vCached.w / fDpr
+        val vLogH = vCached.h / fDpr
+        memScoped {
+            val vDst = alloc<SDL_FRect>()
+            vDst.x = kotlin.math.round((inDeviceBoxX + (inBoxW - vLogW) / 2f) * fDpr) / fDpr
+            vDst.y = kotlin.math.round((inDeviceBoxY + (inBoxH - vLogH) / 2f) * fDpr) / fDpr
+            vDst.w = vLogW
+            vDst.h = vLogH
+            SDL_RenderTexture(vRenderer.reinterpret(), vCached.tex.reinterpret(), null, vDst.ptr)
+        }
+    }
+
     // Coverage gamma: alpha' = 255*(alpha/255)^kTextGamma. kTextGamma < 1
     // boosts partial coverage so antialiased stems read heavier and smoother
     // for light text on a dark background — closer to Skia's gamma-corrected

compose/ui/ui/src/sdlRendererMain/kotlin/com/compose/sdl/renderer/sdl/SdlDisplayList.kt

@@ -0,0 +1,145 @@
+package com.compose.sdl.renderer.sdl
+
+import androidx.compose.ui.text.font.FontVariation
+
+// ==================
+// MARK: SdlDisplayList — captured draw commands for retained replay
+// ==================
+
+/*
+ Phase 4 (RENDERER.md §3/§13). A display list is a layer's drawing captured
+ ONCE in layer-local space and replayed under the layer transform — instead of
+ re-tessellating every frame (DeferredRenderNode) or round-tripping through an
+ offscreen texture (SdlRenderNode: fixed-resolution soft + timing-nondeterministic).
+
+ It is an ORDERED command stream (z-order preserved) mixing three command kinds, each
+ chosen to avoid the expensive recompute the way upstream skiko's Picture + Skia
+ caches do, adapted to SDL:
+   * GeometryBatch — tessellated untextured triangles (layer-local). SDL has no path/
+     tessellation cache, so we cache the vertices (skiko relies on Skia's GPU path
+     cache instead). Owned float copy ⇒ always safe.
+   * TextRun — a "draw this run" command by PARAMETERS, mirroring skiko recording a
+     glyph-run into a Picture. Replay re-looks-up the run texture via the text
+     renderer's own per-run LRU (our analog of Skia's glyph atlas); if the cache
+     evicted it, the lookup re-rasterises — so it NEVER holds a dangling texture
+     pointer. Covers PLAIN text AND spanned text (one TextRun per styled run); only a
+     run with a SpanStyle.background still defers (the background fill isn't captured).
+   * IconRun — a Material Symbols glyph by PARAMETERS; replay re-draws via FreeTypeIcons'
+     own glyph cache (eviction-safe), same lifetime story as TextRun.
+
+ `unsupported` trips on any op not yet capturable (image blits, saveLayer, shadow, a
+ rounded/generic LAYER clip, alpha/blend/colorFilter/renderEffect, span backgrounds)
+ so the node falls back to a crisp block-replay — nothing un-captured ever leaks to
+ the GPU.
+*/
+
+internal sealed class DisplayCommand
+
+/* One captured untextured triangle batch in layer-local coords (8 floats/vertex:
+   pos.xy, color.rgba, tex.xy — Sdl3DrawScope.fVertexData packing). */
+internal class GeometryBatch(
+	val vertexData: FloatArray,
+	val vertexCount: Int,
+) : DisplayCommand()
+
+/* One captured plain text run — replayed by re-looking-up its cached texture
+   (eviction-safe) and blitting at the transformed origin (glyph size stays logical,
+   matching the immediate path's "layer scale reaches position, not glyph size"). */
+internal class TextRun(
+	val fontFamily: String?,
+	val text: String,
+	val fontSizePx: Int,
+	val variations: List<FontVariation.Setting>?,
+	val style: Int,
+	val x: Float,
+	val y: Float,
+	val w: Float,
+	val h: Float,
+	val colorArgb: Int,
+) : DisplayCommand()
+
+/* One captured icon-font glyph (Material Symbols via FreeType). The box origin is
+   layer-local (replay maps it through the layer affine); the box size stays logical
+   (the glyph centres in it, like the immediate icon path). Replay re-draws through
+   FreeTypeIcons' own glyph cache — eviction-safe (re-rasterises if dropped). */
+internal class IconRun(
+	val fontFamily: String,
+	val text: String,
+	val fontSizePx: Int,
+	val variations: List<FontVariation.Setting>?,
+	val boxX: Float,
+	val boxY: Float,
+	val boxW: Float,
+	val boxH: Float,
+	val colorArgb: Int,
+) : DisplayCommand()
+
+/* Sink the drawscope + text renderer capture into during a recording. */
+internal interface GeometrySink {
+	fun captureGeometry(vertexData: FloatArray, vertexCount: Int)
+}
+internal interface TextRunSink {
+	fun captureTextRun(
+		fontFamily: String?,
+		text: String,
+		fontSizePx: Int,
+		variations: List<FontVariation.Setting>?,
+		style: Int,
+		x: Float,
+		y: Float,
+		w: Float,
+		h: Float,
+		colorArgb: Int,
+	)
+	fun markUnsupported()
+}
+
+internal class SdlDisplayList : GeometrySink, TextRunSink {
+	val commands = ArrayList<DisplayCommand>()
+	var unsupported = false
+
+	override fun captureGeometry(vertexData: FloatArray, vertexCount: Int) {
+		if (vertexCount <= 0) return
+		commands.add(GeometryBatch(vertexData.copyOf(vertexCount * kFloatsPerVertex), vertexCount))
+	}
+
+	override fun captureTextRun(
+		fontFamily: String?,
+		text: String,
+		fontSizePx: Int,
+		variations: List<FontVariation.Setting>?,
+		style: Int,
+		x: Float,
+		y: Float,
+		w: Float,
+		h: Float,
+		colorArgb: Int,
+	) {
+		commands.add(TextRun(fontFamily, text, fontSizePx, variations, style, x, y, w, h, colorArgb))
+	}
+
+	override fun markUnsupported() {
+		unsupported = true
+	}
+
+	/* Icon glyphs are captured directly by the canvas (not via a sink) since the
+	   canvas owns the icon-draw path. Box origin is layer-local; size logical. */
+	fun captureIconRun(
+		fontFamily: String,
+		text: String,
+		fontSizePx: Int,
+		variations: List<FontVariation.Setting>?,
+		boxX: Float,
+		boxY: Float,
+		boxW: Float,
+		boxH: Float,
+		colorArgb: Int,
+	) {
+		commands.add(IconRun(fontFamily, text, fontSizePx, variations, boxX, boxY, boxW, boxH, colorArgb))
+	}
+
+	fun clear() {
+		commands.clear()
+		unsupported = false
+	}
+}

compose/ui/ui/src/sdlRendererMain/kotlin/com/compose/sdl/renderer/sdl/SdlDisplayListRenderNode.kt

@@ -0,0 +1,249 @@
+package com.compose.sdl.renderer.sdl
+
+import androidx.compose.ui.geometry.CornerRadius
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.Rect
+import androidx.compose.ui.geometry.RoundRect
+import androidx.compose.ui.geometry.Size
+import androidx.compose.ui.geometry.isUnspecified
+import androidx.compose.ui.graphics.BlendMode
+import androidx.compose.ui.graphics.Canvas
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.ColorFilter
+import androidx.compose.ui.graphics.Matrix
+import androidx.compose.ui.graphics.Outline
+import androidx.compose.ui.graphics.Paint
+import androidx.compose.ui.graphics.Path
+import androidx.compose.ui.graphics.RenderEffect
+import androidx.compose.ui.graphics.drawscope.CanvasDrawScope
+import androidx.compose.ui.graphics.drawscope.DrawScope
+import androidx.compose.ui.graphics.layer.CompositingStrategy
+import androidx.compose.ui.graphics.layer.DefaultCameraDistance
+import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.IntOffset
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.unit.LayoutDirection
+import com.compose.sdl.graphics.NativeRenderNode
+import com.compose.sdl.graphics.NativeShadowCanvas
+import com.compose.sdl.graphics.NativeShapeClipCanvas
+import com.compose.sdl.graphics.offscreenRenderer
+import com.compose.sdl.graphics.prepareLayerTransformationMatrix
+
+// ==================
+// MARK: SdlDisplayListRenderNode — cached-GEOMETRY retained node (Phase 4)
+// ==================
+
+/*
+ The robust retained node. record() captures a leaf's tessellated geometry ONCE (in
+ layer-local space, via a capture canvas that touches no GPU); drawInto() re-emits
+ those cached vertices through the layer transform — crisp under ANY transform
+ (vertices re-transformed, not a resampled texture), bit-exact (no texture round-trip),
+ and with NO per-frame render-target state (so none of the texture node's timing-
+ dependent nondeterminism). See RENDERER.md §3/§13.
+
+ Captures tessellated geometry, plain + spanned text runs, and Material Symbols icon
+ glyphs. A leaf whose block draws something not-yet-capturable (image blits, saveLayer,
+ a rounded/generic layer clip, alpha/blend/colorFilter/renderEffect, span backgrounds)
+ — or that hosts a child layer — trips the capture list's `unsupported` flag / defer
+ path and falls back to a crisp block-replay (== DeferredRenderNode): always correct,
+ just not cached. Image capture is the next step to widen the fast path further.
+*/
+internal class SdlDisplayListRenderNode : NativeRenderNode {
+
+	override var topLeft: IntOffset = IntOffset.Zero
+	override var size: IntSize = IntSize.Zero
+	override var pivot: Offset = Offset.Unspecified
+	override var alpha: Float = 1f
+	override var scaleX: Float = 1f
+	override var scaleY: Float = 1f
+	override var translationX: Float = 0f
+	override var translationY: Float = 0f
+	override var rotationX: Float = 0f
+	override var rotationY: Float = 0f
+	override var rotationZ: Float = 0f
+	override var cameraDistance: Float = DefaultCameraDistance
+	override var shadowElevation: Float = 0f
+	override var ambientShadowColor: Color = Color.Black
+	override var spotShadowColor: Color = Color.Black
+	override var blendMode: BlendMode = BlendMode.SrcOver
+	override var colorFilter: ColorFilter? = null
+	override var renderEffect: RenderEffect? = null
+	override var compositingStrategy: CompositingStrategy = CompositingStrategy.Auto
+	override var clip: Boolean = false
+
+	private var clipOutline: Outline? = null
+	override fun setClipRect(left: Float, top: Float, right: Float, bottom: Float) {
+		clipOutline = Outline.Rectangle(Rect(left, top, right, bottom))
+	}
+	override fun setClipRRect(left: Float, top: Float, right: Float, bottom: Float, radii: FloatArray) {
+		clipOutline = Outline.Rounded(
+			RoundRect(
+				left = left, top = top, right = right, bottom = bottom,
+				topLeftCornerRadius = CornerRadius(radii[0], radii[1]),
+				topRightCornerRadius = CornerRadius(radii[2], radii[3]),
+				bottomRightCornerRadius = CornerRadius(radii[4], radii[5]),
+				bottomLeftCornerRadius = CornerRadius(radii[6], radii[7]),
+			),
+		)
+	}
+	override fun setClipPath(path: Path?) {
+		clipOutline = if (path == null) null else Outline.Generic(path)
+	}
+
+	private var recordedBlock: (DrawScope.() -> Unit)? = null
+	private var recordedDensity: Density = Density(1f)
+	private var recordedLayoutDirection: LayoutDirection = LayoutDirection.Ltr
+	private val drawScope = CanvasDrawScope()
+
+	private var displayList: SdlDisplayList? = null
+	private var deferMode = false   // sticky: block drew a not-yet-capturable op / has a child layer
+	private var sawChild = false    // a child layer drew during this node's record
+
+	// Main-loop-thread stack of nodes currently recording. A child's drawInto (invoked
+	// while its parent's block runs) flags the parent as a non-leaf so the parent
+	// defers — nesting is by DEFER (children composite themselves on the parent's
+	// block-replay), avoiding by-value baking + GPU leaks into the capture pass.
+	private companion object {
+		val fRecordingStack = ArrayList<SdlDisplayListRenderNode>()
+	}
+
+	override fun record(
+		density: Density,
+		layoutDirection: LayoutDirection,
+		size: IntSize,
+		block: DrawScope.() -> Unit,
+	) {
+		recordedDensity = density
+		recordedLayoutDirection = layoutDirection
+		this.size = size
+		recordedBlock = block
+		displayList = null
+
+		val w = size.width
+		val h = size.height
+		val renderer = offscreenRenderer as? Sdl3OffscreenRenderer
+		if (deferMode || w <= 0 || h <= 0 || renderer == null) return
+
+		// Capture at identity base CTM ⇒ layer-local geometry. No GPU touched.
+		val list = SdlDisplayList()
+		val capture = renderer.createCaptureCanvas(list, Size(w.toFloat(), h.toFloat()))
+		sawChild = false
+		fRecordingStack.add(this)
+		try {
+			drawScope.draw(recordedDensity, recordedLayoutDirection, capture, Size(w.toFloat(), h.toFloat()), block)
+		} finally {
+			fRecordingStack.removeAt(fRecordingStack.size - 1)
+			capture.finish()
+		}
+
+		if (list.unsupported || sawChild) {
+			deferMode = true
+		} else {
+			displayList = list
+		}
+	}
+
+	override fun drawInto(canvas: Canvas) {
+		val block = recordedBlock ?: return
+		// Drawn during a PARENT's record → flag the parent as a non-leaf and draw
+		// NOTHING now. The parent will defer to a block-replay that draws us normally;
+		// this prevents leaking our GPU ops into the target-less capture pass and
+		// avoids by-value child baking.
+		if (fRecordingStack.isNotEmpty()) {
+			fRecordingStack[fRecordingStack.size - 1].sawChild = true
+			return
+		}
+		val w = size.width.toFloat()
+		val h = size.height.toFloat()
+
+		canvas.save()
+		canvas.translate(topLeft.x.toFloat(), topLeft.y.toFloat())
+
+		val hasTransform = scaleX != 1f || scaleY != 1f || rotationZ != 0f ||
+			rotationX != 0f || rotationY != 0f || translationX != 0f || translationY != 0f
+		if (hasTransform && w > 0f && h > 0f) {
+			val pivotX = if (pivot.isUnspecified) w / 2f else pivot.x
+			val pivotY = if (pivot.isUnspecified) h / 2f else pivot.y
+			val matrix = Matrix()
+			prepareLayerTransformationMatrix(
+				matrix = matrix,
+				pivotX = pivotX, pivotY = pivotY,
+				translationX = translationX, translationY = translationY,
+				rotationX = rotationX, rotationY = rotationY, rotationZ = rotationZ,
+				scaleX = scaleX, scaleY = scaleY, cameraDistance = cameraDistance,
+			)
+			canvas.concat(matrix)
+		}
+
+		// Drop shadow — parent-space, before content (drawn on the real canvas).
+		if (shadowElevation > 0f && w > 0f && h > 0f) {
+			val outline = clipOutline
+			if (outline != null) {
+				(canvas as? NativeShadowCanvas)
+					?.drawDropShadow(outline, shadowElevation, ambientShadowColor, spotShadowColor)
+			}
+		}
+
+		val list = displayList
+		// Layer-level alpha / blend / colorFilter / renderEffect aren't in the captured
+		// geometry (they're applied at replay); until geo replay folds them in, defer
+		// those to the crisp block-replay.
+		//
+		// A ROUNDED / PATH content clip also forces the block-replay: the fast path
+		// re-emits raw geometry via SDL_RenderGeometry, which the SDL canvas clips only
+		// to a RECT (SDL_SetRenderClipRect). Its rounded-corner mask is an offscreen
+		// realized lazily from drawRect/admitDraw — a path replayBatch bypasses — so a
+		// rounded layer clip would go UNCUT on the fast path. That was the Carousel
+		// diff: each item's morphing rounded mask was ignored, so the coloured card
+		// overflowed its silhouette (wrong shape + apparent horizontal shift). The
+		// block-replay re-runs the block through drawRect, which realizes the mask
+		// correctly (== DeferredRenderNode). A plain RECTANGLE clip is honoured by
+		// SDL_RenderGeometry directly, so it stays on the fast path.
+		val outline = clipOutline
+		val hasShapeClip = clip && (outline is Outline.Rounded || outline is Outline.Generic)
+		val needsCompositing = alpha < 1f || blendMode != BlendMode.SrcOver ||
+			colorFilter != null || renderEffect != null || hasShapeClip
+
+		if (list != null && !needsCompositing && canvas is Sdl3Canvas && w > 0f && h > 0f) {
+			// GEO fast path: re-emit captured commands (geometry + text) through the
+			// current transform. Crisp at any scale/rotation, bit-exact, no texture.
+			// A rectangular content clip narrows the SDL clip rect first (honoured by
+			// SDL_RenderGeometry), keeping cached geometry inside the layer bounds.
+			if (clip && outline is Outline.Rectangle) {
+				canvas.clipRect(outline.rect.left, outline.rect.top, outline.rect.right, outline.rect.bottom)
+			}
+			canvas.replayDisplayList(list)
+		} else {
+			// Block-replay fallback (== DeferredRenderNode): clip + alpha + re-run block.
+			if (clip && w > 0f && h > 0f) applyClip(canvas)
+			val needsAlphaLayer = alpha < 1f && w > 0f && h > 0f
+			if (needsAlphaLayer) {
+				canvas.saveLayer(Rect(0f, 0f, w, h), Paint().apply { alpha = this@SdlDisplayListRenderNode.alpha })
+			}
+			drawScope.draw(recordedDensity, recordedLayoutDirection, canvas, Size(w, h), block)
+			if (needsAlphaLayer) canvas.restore()
+		}
+
+		canvas.restore()
+	}
+
+	private fun applyClip(canvas: Canvas) {
+		when (val outline = clipOutline) {
+			is Outline.Rectangle -> canvas.clipRect(
+				outline.rect.left, outline.rect.top, outline.rect.right, outline.rect.bottom,
+			)
+			is Outline.Rounded -> {
+				val shapeClip = canvas as? NativeShapeClipCanvas
+				if (shapeClip != null) shapeClip.clipRoundRect(outline.roundRect)
+				else { val p = Path().apply { addRoundRect(outline.roundRect) }; canvas.clipPath(p) }
+			}
+			is Outline.Generic -> canvas.clipPath(outline.path)
+			null -> {}
+		}
+	}
+
+	override fun close() {
+		recordedBlock = null
+		displayList = null
+	}
+}

compose/ui/ui/src/sdlRendererMain/kotlin/com/compose/sdl/renderer/sdl/SdlRenderNode.kt

@@ -0,0 +1,294 @@
+package com.compose.sdl.renderer.sdl
+
+import androidx.compose.ui.geometry.CornerRadius
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.Rect
+import androidx.compose.ui.geometry.RoundRect
+import androidx.compose.ui.geometry.Size
+import androidx.compose.ui.geometry.isUnspecified
+import androidx.compose.ui.graphics.BlendMode
+import androidx.compose.ui.graphics.Canvas
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.ColorFilter
+import androidx.compose.ui.graphics.ImageBitmap
+import androidx.compose.ui.graphics.ImageBitmapConfig
+import androidx.compose.ui.graphics.Matrix
+import androidx.compose.ui.graphics.Outline
+import androidx.compose.ui.graphics.Paint
+import androidx.compose.ui.graphics.Path
+import androidx.compose.ui.graphics.RenderEffect
+import androidx.compose.ui.graphics.colorspace.ColorSpaces
+import androidx.compose.ui.graphics.drawscope.CanvasDrawScope
+import androidx.compose.ui.graphics.drawscope.DrawScope
+import androidx.compose.ui.graphics.layer.CompositingStrategy
+import androidx.compose.ui.graphics.layer.DefaultCameraDistance
+import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.IntOffset
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.unit.LayoutDirection
+import com.compose.sdl.graphics.DrawStats
+import com.compose.sdl.graphics.NativeRenderNode
+import com.compose.sdl.graphics.NativeShadowCanvas
+import com.compose.sdl.graphics.NativeShapeClipCanvas
+import com.compose.sdl.graphics.offscreenRenderer
+import com.compose.sdl.graphics.prepareLayerTransformationMatrix
+
+// ==================
+// MARK: SdlRenderNode — RETAINED (texture-cached) NativeRenderNode
+// ==================
+
+/*
+ The SDL caching node — the perf payoff. Records a layer's drawing ONCE into an
+ offscreen SDL texture; replay is a cheap textured blit under the layer transform,
+ NOT a re-tessellation (compare DeferredRenderNode, which re-runs the block every
+ replay). Gated behind CDN_LAYERCACHE=1 while it's verified; DeferredRenderNode
+ stays the default.
+
+ CORRECT-BY-CONSTRUCTION nesting, no upstream divergence: SDL textures composite
+ children BY VALUE, unlike skiko's by-reference Picture, so a naive "cache every
+ layer" would show stale children. Instead we **cache leaves, defer parents**: a
+ node auto-detects on its first record whether its block drew any CHILD layer (via
+ the recording stack below). If it did → it's a parent → fall back to replay-the-
+ block (children composite their own live textures, so no staleness). If it didn't
+ → it's a leaf → keep the texture and just blit it henceforth. Leaves (text runs,
+ icons, shapes — the bulk of static content like the sidebar) stop re-tessellating;
+ parents cheaply re-composite. See RENDERER.md §4b / §13.
+*/
+internal class SdlRenderNode : NativeRenderNode {
+
+	override var topLeft: IntOffset = IntOffset.Zero
+	override var size: IntSize = IntSize.Zero
+	override var pivot: Offset = Offset.Unspecified
+	override var alpha: Float = 1f
+	override var scaleX: Float = 1f
+	override var scaleY: Float = 1f
+	override var translationX: Float = 0f
+	override var translationY: Float = 0f
+	override var rotationX: Float = 0f
+	override var rotationY: Float = 0f
+	override var rotationZ: Float = 0f
+	override var cameraDistance: Float = DefaultCameraDistance
+	override var shadowElevation: Float = 0f
+	override var ambientShadowColor: Color = Color.Black
+	override var spotShadowColor: Color = Color.Black
+	override var blendMode: BlendMode = BlendMode.SrcOver
+	override var colorFilter: ColorFilter? = null
+	override var renderEffect: RenderEffect? = null
+	override var compositingStrategy: CompositingStrategy = CompositingStrategy.Auto
+	override var clip: Boolean = false
+
+	private var clipOutline: Outline? = null
+	override fun setClipRect(left: Float, top: Float, right: Float, bottom: Float) {
+		clipOutline = Outline.Rectangle(Rect(left, top, right, bottom))
+	}
+	override fun setClipRRect(left: Float, top: Float, right: Float, bottom: Float, radii: FloatArray) {
+		clipOutline = Outline.Rounded(
+			RoundRect(
+				left = left, top = top, right = right, bottom = bottom,
+				topLeftCornerRadius = CornerRadius(radii[0], radii[1]),
+				topRightCornerRadius = CornerRadius(radii[2], radii[3]),
+				bottomRightCornerRadius = CornerRadius(radii[4], radii[5]),
+				bottomLeftCornerRadius = CornerRadius(radii[6], radii[7]),
+			),
+		)
+	}
+	override fun setClipPath(path: Path?) {
+		clipOutline = if (path == null) null else Outline.Generic(path)
+	}
+
+	// ============
+	//  Record
+
+	private var recordedBlock: (DrawScope.() -> Unit)? = null
+	private var recordedDensity: Density = Density(1f)
+	private var recordedLayoutDirection: LayoutDirection = LayoutDirection.Ltr
+	private val drawScope = CanvasDrawScope()
+
+	// Caching state (auto-detected — see class doc).
+	private var deferMode = false          // true once a child layer was seen: replay the block
+	private var cached = false             // true once a leaf texture is valid
+	private var bitmap: ImageBitmap? = null
+	private var bitmapW = 0
+	private var bitmapH = 0
+	private var sawChildDuringRecord = false
+
+	override fun record(
+		density: Density,
+		layoutDirection: LayoutDirection,
+		size: IntSize,
+		block: DrawScope.() -> Unit,
+	) {
+		recordedDensity = density
+		recordedLayoutDirection = layoutDirection
+		this.size = size
+		recordedBlock = block
+		cached = false
+
+		val w = size.width
+		val h = size.height
+		val renderer = offscreenRenderer
+		// Parents (deferMode) / zero-size / no offscreen support → just keep the block
+		// and replay it in drawInto (identical to DeferredRenderNode).
+		if (deferMode || w <= 0 || h <= 0 || renderer == null) return
+
+		// Attempt a leaf-cache: render the block into an offscreen texture, watching
+		// for any child layer being drawn (which flips us to deferMode).
+		val bmp = ensureBitmap(w, h) ?: return
+		val target = renderer.createCanvas(bmp) ?: return
+
+		sawChildDuringRecord = false
+		// Watch for image/vector/icon blits: content with partial alpha (a decoded
+		// image, a tinted icon) does NOT round-trip bit-exact through the 8-bit
+		// premultiplied offscreen (the heart painterResource rendered visibly wrong),
+		// so a leaf that draws any image bails to the crisp block-replay. Text/shapes/
+		// solid fills bump other DrawStats counters and stay cached (pixel-equal).
+		// (A true bit-exact cache of such content is Phase 4's cached-geometry list,
+		// which has no texture round-trip.) Costs little: icons are blits, not
+		// tessellation — the big tessellation cost is text, which still caches.
+		val imgBlitsBefore = DrawStats.imageBlits
+		fRecordingStack.add(this)
+		try {
+			// Content is recorded at layer-local origin; the transform is applied at
+			// replay (blit). Clip is baked into the texture so rounded corners are
+			// transparent in the cached pixels.
+			if (clip) applyClip(target)
+			drawScope.draw(recordedDensity, recordedLayoutDirection, target, Size(w.toFloat(), h.toFloat()), block)
+		} finally {
+			fRecordingStack.removeAt(fRecordingStack.size - 1)
+			(target as? com.compose.sdl.graphics.NativeFinishableCanvas)?.finish()
+		}
+		val drewImage = DrawStats.imageBlits > imgBlitsBefore
+
+		if (sawChildDuringRecord || drewImage) {
+			// Not a cacheable leaf (has a child layer, or drew an image) — abandon
+			// caching for this node's lifetime and replay the block instead.
+			deferMode = true
+			releaseBitmap()
+		} else {
+			cached = true
+		}
+	}
+
+	private fun ensureBitmap(w: Int, h: Int): ImageBitmap? {
+		val renderer = offscreenRenderer ?: return null
+		if (bitmap == null || bitmapW != w || bitmapH != h) {
+			releaseBitmap()
+			bitmap = renderer.createImageBitmap(w, h, ImageBitmapConfig.Argb8888, true, ColorSpaces.Srgb)
+			bitmapW = w
+			bitmapH = h
+		}
+		return bitmap
+	}
+
+	private fun releaseBitmap() {
+		(bitmap as? SdlImageBitmap)?.close()
+		bitmap = null
+		bitmapW = 0
+		bitmapH = 0
+	}
+
+	// ============
+	//  Replay
+
+	override fun drawInto(canvas: Canvas) {
+		val block = recordedBlock ?: return
+		val w = size.width.toFloat()
+		val h = size.height.toFloat()
+
+		// If I am being drawn while a parent is recording, that parent has a child
+		// layer (me) → it must NOT leaf-cache. (Detected here rather than in the
+		// parent so it works for any nesting depth.)
+		if (fRecordingStack.isNotEmpty()) fRecordingStack[fRecordingStack.size - 1].sawChildDuringRecord = true
+
+		canvas.save()
+		canvas.translate(topLeft.x.toFloat(), topLeft.y.toFloat())
+
+		val hasTransform = scaleX != 1f || scaleY != 1f || rotationZ != 0f ||
+			rotationX != 0f || rotationY != 0f || translationX != 0f || translationY != 0f
+		if (hasTransform && w > 0f && h > 0f) {
+			val pivotX = if (pivot.isUnspecified) w / 2f else pivot.x
+			val pivotY = if (pivot.isUnspecified) h / 2f else pivot.y
+			val matrix = Matrix()
+			prepareLayerTransformationMatrix(
+				matrix = matrix,
+				pivotX = pivotX, pivotY = pivotY,
+				translationX = translationX, translationY = translationY,
+				rotationX = rotationX, rotationY = rotationY, rotationZ = rotationZ,
+				scaleX = scaleX, scaleY = scaleY, cameraDistance = cameraDistance,
+			)
+			canvas.concat(matrix)
+		}
+
+		// Drop shadow — parent-space, before content (never baked into the texture).
+		if (shadowElevation > 0f && w > 0f && h > 0f) {
+			val outline = clipOutline
+			if (outline != null) {
+				(canvas as? NativeShadowCanvas)
+					?.drawDropShadow(outline, shadowElevation, ambientShadowColor, spotShadowColor)
+			}
+		}
+
+		// Blit the cached texture ONLY for an opaque, untransformed, effect-free leaf
+		// — the exact subset that a plain blit reproduces pixel-equal (verified). We
+		// bail to a crisp block-replay when:
+		//   * scale/rotation — a fixed-resolution texture would bilinear-resample (soft);
+		//   * alpha<1 / blendMode / colorFilter / renderEffect — the blit can't
+		//     reproduce the offscreen compositing (premultiplied-alpha blit differs).
+		// So caching is strictly non-regressing: the static-content case (the win)
+		// blits; everything else replays exactly as before. Phase 4's cached-geometry
+		// display list would widen this (crisp under transform, real compositing).
+		val hasScaleOrRotation = scaleX != 1f || scaleY != 1f ||
+			rotationZ != 0f || rotationX != 0f || rotationY != 0f
+		val needsCompositing = alpha < 1f || blendMode != BlendMode.SrcOver ||
+			colorFilter != null || renderEffect != null
+		val bmp = bitmap
+		if (cached && bmp != null && !hasScaleOrRotation && !needsCompositing && w > 0f && h > 0f) {
+			// Leaf fast path: blit the cached texture (clip already baked in).
+			canvas.drawImageRect(
+				image = bmp,
+				srcOffset = IntOffset.Zero,
+				srcSize = IntSize(bitmapW, bitmapH),
+				dstOffset = IntOffset.Zero,
+				dstSize = IntSize(bitmapW, bitmapH),
+				paint = Paint(),
+			)
+		} else {
+			// Parent / uncached fallback: replay the block (== DeferredRenderNode).
+			if (clip && w > 0f && h > 0f) applyClip(canvas)
+			val needsAlphaLayer = alpha < 1f && w > 0f && h > 0f
+			if (needsAlphaLayer) {
+				canvas.saveLayer(Rect(0f, 0f, w, h), Paint().apply { alpha = this@SdlRenderNode.alpha })
+			}
+			drawScope.draw(recordedDensity, recordedLayoutDirection, canvas, Size(w, h), block)
+			if (needsAlphaLayer) canvas.restore()
+		}
+
+		canvas.restore()
+	}
+
+	private fun applyClip(canvas: Canvas) {
+		when (val outline = clipOutline) {
+			is Outline.Rectangle -> canvas.clipRect(
+				outline.rect.left, outline.rect.top, outline.rect.right, outline.rect.bottom,
+			)
+			is Outline.Rounded -> {
+				val shapeClip = canvas as? NativeShapeClipCanvas
+				if (shapeClip != null) shapeClip.clipRoundRect(outline.roundRect)
+				else { val p = Path().apply { addRoundRect(outline.roundRect) }; canvas.clipPath(p) }
+			}
+			is Outline.Generic -> canvas.clipPath(outline.path)
+			null -> {}
+		}
+	}
+
+	override fun close() {
+		recordedBlock = null
+		releaseBitmap()
+	}
+
+	// The main-loop-thread stack of nodes currently recording. A child's drawInto
+	// (invoked while its parent's block runs) flags the parent as a non-leaf.
+	private companion object {
+		val fRecordingStack = ArrayList<SdlRenderNode>()
+	}
+}

compose/ui/ui/src/skikoRendererMain/kotlin/androidx/compose/ui/graphics/SkiaBackedCanvas.skiko.kt

@@ -0,0 +1,604 @@
+/*
+ * Copyright 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// DERIVED (copy + edit) from compose-multiplatform-core -- MANUAL VENDOR, NON-IDEMPOTENT.
+// VENDOR-BASE: compose/ui/ui-graphics/src/skikoMain/kotlin/androidx/compose/ui/graphics/SkiaBackedCanvas.skiko.kt @ v1.12.0-beta03+dev4483
+// ONLY change vs upstream: this class also implements the port draw contracts
+// (NativeTextCanvas / NativePainterCanvas / NativeShadowCanvas / NativeFinishableCanvas) so
+// the port text engine (SkiaTextRenderer, P3.1 metrics) + resource-image cache + elevation
+// shadows keep working on the Skia leg, which now draws through THIS canvas instead of the
+// retired project SkiaCanvas. Bridged methods forward to `skiaLeafDrawer` using
+// `internalSkiaCanvas`. See RENDERER.md (B6.1, section 4).
+
+package androidx.compose.ui.graphics
+
+import androidx.compose.runtime.InternalComposeApi
+import com.compose.sdl.renderer.skia.skiaLeafDrawer
+import org.jetbrains.skia.FilterBlurMode
+import org.jetbrains.skia.MaskFilter
+import org.jetbrains.skia.RRect as SkRRect
+import org.jetbrains.skia.Color as SkColorNs
+import androidx.compose.ui.InternalComposeUiApi
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.Rect
+import androidx.compose.ui.unit.IntOffset
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.util.fastForEach
+import org.jetbrains.skia.Canvas as SkCanvas
+import org.jetbrains.skia.ClipMode as SkClipMode
+import org.jetbrains.skia.CubicResampler
+import org.jetbrains.skia.FilterMipmap
+import org.jetbrains.skia.FilterMode
+import org.jetbrains.skia.Image
+import org.jetbrains.skia.Matrix44
+import org.jetbrains.skia.MipmapMode
+import org.jetbrains.skia.Paint as SkPaint
+import org.jetbrains.skia.SamplingMode
+import org.jetbrains.skia.impl.use
+
+@Deprecated(
+    message = "Use direct reference to org.jetbrains.skia.Canvas instead of typealias",
+    replaceWith = ReplaceWith("Canvas", "org.jetbrains.skia.Canvas"),
+    level = DeprecationLevel.ERROR,
+)
+actual typealias NativeCanvas = SkCanvas
+
+internal actual fun ActualCanvas(image: ImageBitmap): Canvas {
+    val skiaBitmap = image.asSkiaBitmap()
+    require(!skiaBitmap.isImmutable) {
+        "Cannot draw on immutable ImageBitmap"
+    }
+    return SkiaBackedCanvas(SkCanvas(skiaBitmap))
+}
+
+/**
+ * Convert the [org.jetbrains.skia.Canvas] instance into a Compose-compatible Canvas
+ */
+fun SkCanvas.asComposeCanvas(): Canvas = SkiaBackedCanvas(this)
+
+/**
+ * Provides access to the underlying [org.jetbrains.skia.Canvas] instance.
+ *
+ * It throws an exception if accessed on unsupported types.
+ */
+val Canvas.skiaCanvas: SkCanvas
+    get() {
+        requirePrecondition(this is SkiaBackedCanvas) {
+            "Extracting skia canvas reference is only supported from androidx.compose.ui.graphics.SkiaBackedCanvas instances but received ${this::class}"
+        }
+        return internalSkiaCanvas
+    }
+
+@Deprecated(
+    message = "Naming alignment to avoid ambiguity: use [Canvas.skiaCanvas] extension instead",
+    replaceWith = ReplaceWith("skiaCanvas", "androidx.compose.ui.graphics.skiaCanvas"),
+)
+val Canvas.nativeCanvas: SkCanvas
+    get() = skiaCanvas
+
+// This was added for internal usage from old render layers (another submodule),
+// but wasn't properly marked as internal. Keep it as deprecated for some time to be safe.
+@InternalComposeApi
+@Deprecated(
+    level = DeprecationLevel.ERROR,
+    message = "This API is not supposed to be used outside of Compose UI package"
+)
+var Canvas.alphaMultiplier: Float
+    get() = (this as SkiaBackedCanvas).alphaMultiplier
+    set(value) { (this as SkiaBackedCanvas).alphaMultiplier = value }
+
+internal class SkiaBackedCanvas(
+    internal val internalSkiaCanvas: SkCanvas,
+) : Canvas,
+    com.compose.sdl.text.NativeTextCanvas,
+    com.compose.sdl.graphics.NativePainterCanvas,
+    com.compose.sdl.graphics.NativeShadowCanvas,
+    com.compose.sdl.graphics.NativeFinishableCanvas {
+    internal var alphaMultiplier: Float = 1.0f
+
+    private fun Paint.asSkiaPaintWithAppliedAlphaMultiplier(): SkPaint {
+        require(this is SkiaBackedPaint)
+        this.alphaMultiplier = this@SkiaBackedCanvas.alphaMultiplier
+        return internalSkiaPaint
+    }
+
+    override fun save() {
+        internalSkiaCanvas.save()
+    }
+
+    override fun restore() {
+        internalSkiaCanvas.restore()
+    }
+
+    override fun saveLayer(bounds: Rect, paint: Paint) {
+        internalSkiaCanvas.saveLayer(
+            bounds.left,
+            bounds.top,
+            bounds.right,
+            bounds.bottom,
+            paint.asSkiaPaintWithAppliedAlphaMultiplier()
+        )
+    }
+
+    override fun translate(dx: Float, dy: Float) {
+        internalSkiaCanvas.translate(dx, dy)
+    }
+
+    override fun scale(sx: Float, sy: Float) {
+        internalSkiaCanvas.scale(sx, sy)
+    }
+
+    override fun rotate(degrees: Float) {
+        internalSkiaCanvas.rotate(degrees)
+    }
+
+    override fun skew(sx: Float, sy: Float) {
+        internalSkiaCanvas.skew(sx, sy)
+    }
+
+    override fun concat(matrix: Matrix) {
+        if (!matrix.isIdentity()) {
+            internalSkiaCanvas.concat(matrix.toSkia())
+        }
+    }
+
+    override fun clipRect(left: Float, top: Float, right: Float, bottom: Float, clipOp: ClipOp) {
+        val antiAlias = true
+        internalSkiaCanvas.clipRect(
+            left = left,
+            top = top,
+            right = right,
+            bottom = bottom,
+            mode = clipOp.toSkia(),
+            antiAlias = antiAlias
+        )
+    }
+
+    @OptIn(InternalComposeUiApi::class)
+    override fun clipPath(path: Path, clipOp: ClipOp) {
+        val antiAlias = true
+        internalSkiaCanvas.clipPath(path.materializeSkiaPath(), clipOp.toSkia(), antiAlias)
+    }
+
+    override fun drawLine(p1: Offset, p2: Offset, paint: Paint) {
+        internalSkiaCanvas.drawLine(
+            x0 = p1.x,
+            y0 = p1.y,
+            x1 = p2.x,
+            y1 = p2.y,
+            paint = paint.asSkiaPaintWithAppliedAlphaMultiplier(),
+        )
+    }
+
+    override fun drawRect(left: Float, top: Float, right: Float, bottom: Float, paint: Paint) {
+        internalSkiaCanvas.drawRect(
+            left = left,
+            top = top,
+            right = right,
+            bottom = bottom,
+            paint = paint.asSkiaPaintWithAppliedAlphaMultiplier(),
+        )
+    }
+
+    override fun drawRoundRect(
+        left: Float,
+        top: Float,
+        right: Float,
+        bottom: Float,
+        radiusX: Float,
+        radiusY: Float,
+        paint: Paint
+    ) {
+        internalSkiaCanvas.drawRRect(
+            left = left,
+            top = top,
+            right = right,
+            bottom = bottom,
+            radii = floatArrayOf(radiusX, radiusY),
+            paint = paint.asSkiaPaintWithAppliedAlphaMultiplier(),
+        )
+    }
+
+    override fun drawOval(left: Float, top: Float, right: Float, bottom: Float, paint: Paint) {
+        internalSkiaCanvas.drawOval(
+            left = left,
+            top = top,
+            right = right,
+            bottom = bottom,
+            paint = paint.asSkiaPaintWithAppliedAlphaMultiplier(),
+        )
+    }
+
+    override fun drawCircle(center: Offset, radius: Float, paint: Paint) {
+        internalSkiaCanvas.drawCircle(
+            x = center.x,
+            y = center.y,
+            radius = radius,
+            paint = paint.asSkiaPaintWithAppliedAlphaMultiplier(),
+        )
+    }
+
+    override fun drawArc(
+        left: Float,
+        top: Float,
+        right: Float,
+        bottom: Float,
+        startAngle: Float,
+        sweepAngle: Float,
+        useCenter: Boolean,
+        paint: Paint
+    ) {
+        internalSkiaCanvas.drawArc(
+            left = left,
+            top = top,
+            right = right,
+            bottom = bottom,
+            startAngle = startAngle,
+            sweepAngle = sweepAngle,
+            includeCenter = useCenter,
+            paint = paint.asSkiaPaintWithAppliedAlphaMultiplier(),
+        )
+    }
+
+    @OptIn(InternalComposeUiApi::class)
+    override fun drawPath(path: Path, paint: Paint) {
+        internalSkiaCanvas.drawPath(
+            path = path.materializeSkiaPath(),
+            paint = paint.asSkiaPaintWithAppliedAlphaMultiplier(),
+        )
+    }
+
+    override fun drawImage(image: ImageBitmap, topLeftOffset: Offset, paint: Paint) {
+        drawImageRect(
+            image = image,
+            srcLeft = 0f,
+            srcTop = 0f,
+            srcRight = image.width.toFloat(),
+            srcBottom = image.height.toFloat(),
+            dstLeft = topLeftOffset.x,
+            dstTop = topLeftOffset.y,
+            dstRight = topLeftOffset.x + image.width.toFloat(),
+            dstBottom = topLeftOffset.y + image.height.toFloat(),
+            paint = paint,
+        )
+    }
+
+    override fun drawImageRect(
+        image: ImageBitmap,
+        srcOffset: IntOffset,
+        srcSize: IntSize,
+        dstOffset: IntOffset,
+        dstSize: IntSize,
+        paint: Paint
+    ) {
+        drawImageRect(
+            image = image,
+            srcLeft = srcOffset.x.toFloat(),
+            srcTop = srcOffset.y.toFloat(),
+            srcRight = srcOffset.x.toFloat() + srcSize.width.toFloat(),
+            srcBottom = srcOffset.y.toFloat() + srcSize.height.toFloat(),
+            dstLeft = dstOffset.x.toFloat(),
+            dstTop = dstOffset.y.toFloat(),
+            dstRight = dstOffset.x.toFloat() + dstSize.width.toFloat(),
+            dstBottom = dstOffset.y.toFloat() + dstSize.height.toFloat(),
+            paint = paint,
+        )
+    }
+
+    // TODO(demin): probably this method should be in the common Canvas
+    private fun drawImageRect(
+        image: ImageBitmap,
+        srcLeft: Float,
+        srcTop: Float,
+        srcRight: Float,
+        srcBottom: Float,
+        dstLeft: Float,
+        dstTop: Float,
+        dstRight: Float,
+        dstBottom: Float,
+        paint: Paint
+    ) {
+        val bitmap = image.asSkiaBitmap()
+
+        Image.makeFromBitmap(bitmap).use { skiaImage ->
+            internalSkiaCanvas.drawImageRect(
+                image = skiaImage,
+                srcLeft = srcLeft,
+                srcTop = srcTop,
+                srcRight = srcRight,
+                srcBottom = srcBottom,
+                dstLeft = dstLeft,
+                dstTop = dstTop,
+                dstRight = dstRight,
+                dstBottom = dstBottom,
+                samplingMode = paint.filterQuality.toSkia(),
+                paint = paint.asSkiaPaintWithAppliedAlphaMultiplier(),
+                strict = true,
+            )
+        }
+    }
+
+    override fun drawPoints(pointMode: PointMode, points: List<Offset>, paint: Paint) {
+        when (pointMode) {
+            // Draw a line between each pair of points, each point has at most one line
+            // If the number of points is odd, then the last point is ignored.
+            PointMode.Lines -> drawLines(points, paint, 2)
+
+            // Connect each adjacent point with a line
+            PointMode.Polygon -> drawLines(points, paint, 1)
+
+            // Draw a point at each provided coordinate
+            PointMode.Points -> drawPoints(points, paint)
+        }
+    }
+
+    override fun enableZ() = Unit
+
+    override fun disableZ() = Unit
+
+    private fun drawPoints(points: List<Offset>, paint: Paint) {
+        val skiaPaint = paint.asSkiaPaintWithAppliedAlphaMultiplier()
+        points.fastForEach { point ->
+            internalSkiaCanvas.drawPoint(
+                x = point.x,
+                y = point.y,
+                paint = skiaPaint,
+            )
+        }
+    }
+
+    /**
+     * Draw lines connecting points based on the corresponding step.
+     *
+     * ex. 3 points with a step of 1 would draw 2 lines between the first and second points
+     * and another between the second and third
+     *
+     * ex. 4 points with a step of 2 would draw 2 lines between the first and second and another
+     * between the third and fourth. If there is an odd number of points, the last point is
+     * ignored
+     *
+     * @see drawRawLines
+     */
+    private fun drawLines(points: List<Offset>, paint: Paint, stepBy: Int) {
+        if (points.size >= 2) {
+            val skiaPaint = paint.asSkiaPaintWithAppliedAlphaMultiplier()
+            var i = 0
+            while (i < points.size - 1) {
+                val p1 = points[i]
+                val p2 = points[i + 1]
+                internalSkiaCanvas.drawLine(p1.x, p1.y, p2.x, p2.y, skiaPaint)
+                i += stepBy
+            }
+        }
+    }
+
+    /**
+     * @throws IllegalArgumentException if a non even number of points is provided
+     */
+    override fun drawRawPoints(pointMode: PointMode, points: FloatArray, paint: Paint) {
+        if (points.size % 2 != 0) {
+            throw IllegalArgumentException("points must have an even number of values")
+        }
+        when (pointMode) {
+            PointMode.Lines -> drawRawLines(points, paint, 2)
+            PointMode.Polygon -> drawRawLines(points, paint, 1)
+            PointMode.Points -> drawRawPoints(points, paint, 2)
+        }
+    }
+
+    private fun drawRawPoints(points: FloatArray, paint: Paint, stepBy: Int) {
+        if (points.size % 2 == 0) {
+            val skiaPaint = paint.asSkiaPaintWithAppliedAlphaMultiplier()
+            var i = 0
+            while (i < points.size - 1) {
+                val x = points[i]
+                val y = points[i + 1]
+                internalSkiaCanvas.drawPoint(x, y, skiaPaint)
+                i += stepBy
+            }
+        }
+    }
+
+    /**
+     * Draw lines connecting points based on the corresponding step. The points are interpreted
+     * as x, y coordinate pairs in alternating index positions
+     *
+     * ex. 3 points with a step of 1 would draw 2 lines between the first and second points
+     * and another between the second and third
+     *
+     * ex. 4 points with a step of 2 would draw 2 lines between the first and second and another
+     * between the third and fourth. If there is an odd number of points, the last point is
+     * ignored
+     *
+     * @see drawLines
+     */
+    private fun drawRawLines(points: FloatArray, paint: Paint, stepBy: Int) {
+        // Float array is treated as alternative set of x and y coordinates
+        // x1, y1, x2, y2, x3, y3, ... etc.
+        if (points.size >= 4 && points.size % 2 == 0) {
+            val skiaPaint = paint.asSkiaPaintWithAppliedAlphaMultiplier()
+            var i = 0
+            while (i < points.size - 3) {
+                val x1 = points[i]
+                val y1 = points[i + 1]
+                val x2 = points[i + 2]
+                val y2 = points[i + 3]
+                internalSkiaCanvas.drawLine(x1, y1, x2, y2, skiaPaint)
+                i += stepBy * 2
+            }
+        }
+    }
+
+    override fun drawVertices(vertices: Vertices, blendMode: BlendMode, paint: Paint) {
+        internalSkiaCanvas.drawVertices(
+            vertexMode = vertices.vertexMode.toSkiaVertexMode(),
+            positions = vertices.positions,
+            colors = vertices.colors,
+            texCoords = vertices.textureCoordinates,
+            indices = vertices.indices,
+            blendMode = blendMode.toSkia(),
+            paint = paint.asSkiaPaintWithAppliedAlphaMultiplier(),
+        )
+    }
+
+    private fun ClipOp.toSkia() = when (this) {
+        ClipOp.Difference -> SkClipMode.DIFFERENCE
+        ClipOp.Intersect -> SkClipMode.INTERSECT
+        else -> SkClipMode.INTERSECT
+    }
+
+    private fun Matrix.toSkia() = Matrix44(
+        this[0, 0],
+        this[1, 0],
+        this[2, 0],
+        this[3, 0],
+
+        this[0, 1],
+        this[1, 1],
+        this[2, 1],
+        this[3, 1],
+
+        this[0, 2],
+        this[1, 2],
+        this[2, 2],
+        this[3, 2],
+
+        this[0, 3],
+        this[1, 3],
+        this[2, 3],
+        this[3, 3]
+    )
+
+    // These constants are chosen to correspond the old implementation of SkFilterQuality:
+    // https://github.com/google/skia/blob/1f193df9b393d50da39570dab77a0bb5d28ec8ef/src/image/SkImage.cpp#L809
+    // https://github.com/google/skia/blob/1f193df9b393d50da39570dab77a0bb5d28ec8ef/include/core/SkSamplingOptions.h#L86
+    private fun FilterQuality.toSkia(): SamplingMode = when (this) {
+        FilterQuality.Low -> FilterMipmap(FilterMode.LINEAR, MipmapMode.NONE)
+        FilterQuality.Medium -> FilterMipmap(FilterMode.LINEAR, MipmapMode.NEAREST)
+        FilterQuality.High -> CubicResampler(1 / 3.0f, 1 / 3.0f)
+        else -> FilterMipmap(FilterMode.NEAREST, MipmapMode.NONE)
+    }
+
+    // ============
+    //  Port draw contracts (B6.1) -- forward to the port renderers via skiaLeafDrawer.
+
+    override fun finish() { /* Skia save/restore is balanced per call */ }
+
+    override fun drawNativeText(
+        inText: String,
+        inSpans: List<androidx.compose.ui.text.AnnotatedString.Range<androidx.compose.ui.text.SpanStyle>>?,
+        inX: Float,
+        inY: Float,
+        inBoxWidth: Float,
+        inBoxHeight: Float,
+        inColor: Color,
+        inFontSizePx: Int,
+        inTextAlign: androidx.compose.ui.text.style.TextAlign,
+        inSoftWrap: Boolean,
+        inFontFamily: String?,
+        inFontVariations: List<androidx.compose.ui.text.font.FontVariation.Setting>?,
+        inBaseItalic: Boolean,
+        inTextDecoration: androidx.compose.ui.text.style.TextDecoration?,
+        inLineHeightPx: Float,
+        inTrimFirstLine: Boolean,
+    ) {
+        val drawer = skiaLeafDrawer ?: return
+        val vUnderline = inTextDecoration?.contains(androidx.compose.ui.text.style.TextDecoration.Underline) == true
+        val vLineThrough = inTextDecoration?.contains(androidx.compose.ui.text.style.TextDecoration.LineThrough) == true
+        drawer.textRenderer.drawText(
+            inCanvas = internalSkiaCanvas,
+            inText = inText,
+            inX = inX,
+            inY = inY,
+            inBoxWidth = inBoxWidth.toInt(),
+            inBoxHeight = inBoxHeight.toInt(),
+            inColor = inColor,
+            inFontSize = inFontSizePx,
+            inAlign = inTextAlign,
+            inSoftWrap = inSoftWrap,
+            inFontFamily = inFontFamily,
+            inFontVariations = inFontVariations,
+            inSpans = inSpans,
+            inBaseItalic = inBaseItalic,
+            inBaseUnderline = vUnderline,
+            inBaseLineThrough = vLineThrough,
+            inLineHeightPx = inLineHeightPx,
+            inTrimFirstLine = inTrimFirstLine,
+        )
+    }
+
+    override fun drawNativePainter(
+        inResourcePath: String,
+        inKind: com.compose.sdl.res.ResourceKind,
+        inX: Float,
+        inY: Float,
+        inWidth: Float,
+        inHeight: Float,
+        inContentScale: androidx.compose.ui.layout.ContentScale,
+        inAlpha: Float,
+    ) {
+        val drawer = skiaLeafDrawer ?: return
+        drawer.imageCache.draw(
+            inCanvas = internalSkiaCanvas,
+            inPath = inResourcePath,
+            inKind = inKind,
+            inX = inX,
+            inY = inY,
+            inW = inWidth,
+            inH = inHeight,
+            inScale = inContentScale,
+            inAlpha = inAlpha,
+        )
+    }
+
+    @OptIn(InternalComposeUiApi::class)
+    override fun drawDropShadow(
+        inOutline: Outline,
+        inElevationPx: Float,
+        inAmbientColor: Color,
+        inSpotColor: Color,
+    ) {
+        if (inElevationPx <= 0f) return
+        val vOffsetY = inElevationPx * 0.4f
+        val vSpot = inSpotColor.copy(alpha = 0.28f * inSpotColor.alpha)
+        val vPaint = SkPaint().apply {
+            color = SkColorNs.makeARGB(
+                (vSpot.alpha * 255f).toInt().coerceIn(0, 255),
+                (vSpot.red * 255f).toInt().coerceIn(0, 255),
+                (vSpot.green * 255f).toInt().coerceIn(0, 255),
+                (vSpot.blue * 255f).toInt().coerceIn(0, 255),
+            )
+            maskFilter = MaskFilter.makeBlur(FilterBlurMode.NORMAL, sigma = inElevationPx * 0.5f + 0.5f)
+        }
+        when (inOutline) {
+            is Outline.Rectangle -> {
+                val r = inOutline.rect
+                internalSkiaCanvas.drawRRect(SkRRect.makeLTRB(r.left, r.top + vOffsetY, r.right, r.bottom + vOffsetY, 0f), vPaint)
+            }
+            is Outline.Rounded -> {
+                val rr = inOutline.roundRect
+                internalSkiaCanvas.drawRRect(SkRRect.makeLTRB(rr.left, rr.top + vOffsetY, rr.right, rr.bottom + vOffsetY, rr.topLeftCornerRadius.x), vPaint)
+            }
+            is Outline.Generic -> {
+                internalSkiaCanvas.save()
+                internalSkiaCanvas.translate(0f, vOffsetY)
+                internalSkiaCanvas.drawPath(inOutline.path.materializeSkiaPath(), vPaint)
+                internalSkiaCanvas.restore()
+            }
+        }
+        vPaint.close()
+    }
+}

compose/ui/ui/src/skikoRendererMain/kotlin/androidx/compose/ui/graphics/SkiaImageAsset.skiko.kt

@@ -0,0 +1,183 @@
+@file:Suppress("OPTIONAL_DECLARATION_USAGE_IN_NON_COMMON_SOURCE", "LESS_VISIBLE_TYPE_ACCESS_IN_INLINE")
+
+/*
+ * Copyright 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// DERIVED (copy + edit) from compose-multiplatform-core -- MANUAL VENDOR, NON-IDEMPOTENT.
+// VENDOR-BASE: compose/ui/ui-graphics/src/skikoMain/kotlin/androidx/compose/ui/graphics/SkiaImageAsset.skiko.kt @ v1.12.0-beta03+dev4483
+// FLATTENED for our single-native-source-set layout: upstream splits Image.toBitmap /
+// ByteArray.putBytesInto into expect (here) + actual (skikoExcludingWebMain / nativeMain).
+// Those collapse into the same skikoRenderer source set here, which is illegal, so the two
+// bodies are inlined (impls from Actuals.skikoExcludingWeb.kt + NativeImageAsset.native.kt).
+// Everything else is byte-for-byte upstream. See RENDERER.md B6.1.
+
+package androidx.compose.ui.graphics
+
+import androidx.compose.ui.graphics.colorspace.ColorSpace
+import kotlinx.cinterop.ExperimentalForeignApi
+import kotlinx.cinterop.addressOf
+import kotlinx.cinterop.usePinned
+import platform.posix.memcpy
+import androidx.compose.ui.graphics.colorspace.ColorSpaces
+import kotlin.math.abs
+import org.jetbrains.skia.Bitmap
+import org.jetbrains.skia.ColorAlphaType
+import org.jetbrains.skia.ColorInfo
+import org.jetbrains.skia.ColorType
+import org.jetbrains.skia.Image
+import org.jetbrains.skia.ImageInfo
+
+/**
+ * Create an [ImageBitmap] from the given [Bitmap]. Note this does
+ * not create a copy of the original [Bitmap] and changes to it
+ * will modify the returned [ImageBitmap]
+ */
+fun Bitmap.asComposeImageBitmap(): ImageBitmap = SkiaBackedImageBitmap(this)
+
+/**
+ * Create an [ImageBitmap] from the given [Image].
+ */
+fun Image.toComposeImageBitmap(): ImageBitmap = SkiaBackedImageBitmap(toBitmap())
+
+// Split upstream into expect/actual (fast non-web impl); inlined here (flat source set).
+internal fun Image.toBitmap(): Bitmap {
+    val bitmap = Bitmap()
+    bitmap.allocPixels(ImageInfo.makeN32(width, height, ColorAlphaType.PREMUL))
+    val canvas = org.jetbrains.skia.Canvas(bitmap)
+    canvas.drawImage(this, 0f, 0f)
+    bitmap.setImmutable()
+    return bitmap
+}
+
+internal actual fun ActualImageBitmap(
+    width: Int,
+    height: Int,
+    config: ImageBitmapConfig,
+    hasAlpha: Boolean,
+    colorSpace: ColorSpace
+): ImageBitmap {
+    require(width > 0 && height > 0) { "width and height must be > 0" }
+    val colorType = config.toSkiaColorType()
+    val alphaType = if (hasAlpha) ColorAlphaType.PREMUL else ColorAlphaType.OPAQUE
+    val skiaColorSpace = colorSpace.toSkiaColorSpace()
+    val colorInfo = ColorInfo(colorType, alphaType, skiaColorSpace)
+    val imageInfo = ImageInfo(colorInfo, width, height)
+    val bitmap = Bitmap()
+    bitmap.allocPixels(imageInfo)
+    return SkiaBackedImageBitmap(bitmap)
+}
+
+/**
+ * Obtain a reference to the [org.jetbrains.skia.Bitmap]
+ *
+ * @Throws UnsupportedOperationException if this [ImageBitmap] is not backed by an
+ * org.jetbrains.skia.Image
+ */
+fun ImageBitmap.asSkiaBitmap(): Bitmap =
+    when (this) {
+        is SkiaBackedImageBitmap -> bitmap
+        else -> throw UnsupportedOperationException("Unable to obtain org.jetbrains.skia.Image")
+    }
+
+private class SkiaBackedImageBitmap(val bitmap: Bitmap) : ImageBitmap {
+    override val colorSpace = bitmap.colorSpace.toComposeColorSpace()
+    override val config = bitmap.colorType.toComposeConfig()
+    override val hasAlpha = !bitmap.isOpaque
+    override val height get() = bitmap.height
+    override val width get() = bitmap.width
+    override fun prepareToDraw() = Unit
+
+    override fun readPixels(
+        buffer: IntArray,
+        startX: Int,
+        startY: Int,
+        width: Int,
+        height: Int,
+        bufferOffset: Int,
+        stride: Int
+    ) {
+        // similar to https://cs.android.com/android/platform/superproject/+/42c50042d1f05d92ecc57baebe3326a57aeecf77:frameworks/base/graphics/java/android/graphics/Bitmap.java;l=2007
+        val lastScanline: Int = bufferOffset + (height - 1) * stride
+        require(startX >= 0 && startY >= 0)
+        require(width > 0 && startX + width <= this.width)
+        require(height > 0 && startY + height <= this.height)
+        require(abs(stride) >= width)
+        require(bufferOffset >= 0 && bufferOffset + width <= buffer.size)
+        require(lastScanline >= 0 && lastScanline + width <= buffer.size)
+
+        // similar to https://cs.android.com/android/platform/superproject/+/9054ca2b342b2ea902839f629e820546d8a2458b:frameworks/base/libs/hwui/jni/Bitmap.cpp;l=898;bpv=1
+        val colorInfo = ColorInfo(
+            ColorType.BGRA_8888,
+            ColorAlphaType.UNPREMUL,
+            org.jetbrains.skia.ColorSpace.sRGB
+        )
+        val imageInfo = ImageInfo(colorInfo, width, height)
+        val bytesPerPixel = 4
+        val bytes = bitmap.readPixels(imageInfo, stride * bytesPerPixel, startX, startY)!!
+        bytes.putBytesInto(buffer, bufferOffset, bytes.size / bytesPerPixel)
+    }
+}
+
+@OptIn(ExperimentalForeignApi::class)
+internal fun ByteArray.putBytesInto(array: IntArray, offset: Int, length: Int) {
+    this.usePinned { bytes ->
+        array.usePinned { ints ->
+            // Assuming little endian.
+            memcpy(ints.addressOf(offset), bytes.addressOf(0), (length * 4).toULong())
+        }
+    }
+}
+
+// TODO(demin): [API] maybe we should use:
+//  `else -> throw UnsupportedOperationException()`
+//  in toSkiaColorType/toComposeConfig/toComposeColorSpace/toSkiaColorSpace
+//  see [https://android-review.googlesource.com/c/platform/frameworks/support/+/1429835/comment/c219501b_63c3d1fe/]
+
+private fun ImageBitmapConfig.toSkiaColorType() = when (this) {
+    ImageBitmapConfig.Argb8888 -> ColorType.N32
+    ImageBitmapConfig.Alpha8 -> ColorType.ALPHA_8
+    ImageBitmapConfig.Rgb565 -> ColorType.RGB_565
+    ImageBitmapConfig.F16 -> ColorType.RGBA_F16
+    else -> ColorType.N32
+}
+
+private fun ColorType.toComposeConfig() = when (this) {
+    ColorType.N32 -> ImageBitmapConfig.Argb8888
+    ColorType.ALPHA_8 -> ImageBitmapConfig.Alpha8
+    ColorType.RGB_565 -> ImageBitmapConfig.Rgb565
+    ColorType.RGBA_F16 -> ImageBitmapConfig.F16
+    else -> ImageBitmapConfig.Argb8888
+}
+
+private fun org.jetbrains.skia.ColorSpace?.toComposeColorSpace(): ColorSpace {
+    return when (this) {
+        org.jetbrains.skia.ColorSpace.sRGB -> ColorSpaces.Srgb
+        org.jetbrains.skia.ColorSpace.sRGBLinear -> ColorSpaces.LinearSrgb
+        org.jetbrains.skia.ColorSpace.displayP3 -> ColorSpaces.DisplayP3
+        else -> ColorSpaces.Srgb
+    }
+}
+
+// TODO(demin): support all color spaces.
+//  to do this we need to implement SkColorSpace::MakeRGB in skia
+private fun ColorSpace.toSkiaColorSpace(): org.jetbrains.skia.ColorSpace {
+    return when (this) {
+        ColorSpaces.Srgb -> org.jetbrains.skia.ColorSpace.sRGB
+        ColorSpaces.LinearSrgb -> org.jetbrains.skia.ColorSpace.sRGBLinear
+        ColorSpaces.DisplayP3 -> org.jetbrains.skia.ColorSpace.displayP3
+        else -> org.jetbrains.skia.ColorSpace.sRGB
+    }
+}

compose/ui/ui/src/skikoRendererMain/kotlin/com/compose/sdl/graphics/GraphicsContextFactory.skia.kt

@@ -0,0 +1,13 @@
+package com.compose.sdl.graphics
+
+import androidx.compose.ui.graphics.GraphicsContext
+import androidx.compose.ui.graphics.SkiaGraphicsContext
+
+// ==================
+// MARK: createGraphicsContext — Skia renderer actual (B6.2)
+// ==================
+
+/* The Skia leg uses upstream's SkiaGraphicsContext, which owns a skiko
+   RenderNodeContext and creates upstream GraphicsLayer(skiko.RenderNode) instances.
+   See RENDERER.md (B6.2, section 4). */
+internal actual fun createGraphicsContext(): GraphicsContext = SkiaGraphicsContext()

compose/ui/ui/src/skikoRendererMain/kotlin/com/compose/sdl/renderer/skia/SkiaCanvas.kt

@@ -1,503 +0,0 @@
-package com.compose.sdl.renderer.skia
-
-import androidx.compose.ui.geometry.Offset
-import androidx.compose.ui.geometry.Rect
-import androidx.compose.ui.geometry.Size
-import androidx.compose.ui.graphics.BlendMode
-import androidx.compose.ui.graphics.Canvas
-import androidx.compose.ui.graphics.ClipOp
-import androidx.compose.ui.graphics.Color as ComposeColor
-import androidx.compose.ui.graphics.ImageBitmap
-import androidx.compose.ui.graphics.LinearGradient
-import androidx.compose.ui.graphics.Matrix
-import androidx.compose.ui.graphics.Paint
-import androidx.compose.ui.graphics.PaintingStyle
-import androidx.compose.ui.graphics.Path as ComposePath
-import androidx.compose.ui.graphics.RadialGradient
-import androidx.compose.ui.graphics.SkiaBackedPath
-import androidx.compose.ui.graphics.SolidColor
-import androidx.compose.ui.graphics.SweepGradient
-import androidx.compose.ui.graphics.TileMode as ComposeTileMode
-import androidx.compose.ui.graphics.asSkiaColorFilter
-import androidx.compose.ui.graphics.asSkiaPath
-import androidx.compose.ui.graphics.PointMode
-import androidx.compose.ui.graphics.StrokeCap as ComposeStrokeCap
-import androidx.compose.ui.graphics.Vertices
-import androidx.compose.ui.graphics.toSkia
-import com.compose.sdl.graphics.PathCommand
-import com.compose.sdl.graphics.ProjectPath
-import com.compose.sdl.graphics.a8
-import com.compose.sdl.graphics.b8
-import com.compose.sdl.graphics.g8
-import com.compose.sdl.graphics.gradientCenter
-import com.compose.sdl.graphics.gradientColors
-import com.compose.sdl.graphics.gradientEnd
-import com.compose.sdl.graphics.gradientRadius
-import com.compose.sdl.graphics.gradientStart
-import com.compose.sdl.graphics.gradientStops
-import com.compose.sdl.graphics.gradientTileMode
-import com.compose.sdl.graphics.r8
-import org.jetbrains.skia.Canvas as SkCanvas
-import org.jetbrains.skia.ClipMode
-import org.jetbrains.skia.Color as SkColor
-import org.jetbrains.skia.Color4f
-import org.jetbrains.skia.FilterTileMode
-import org.jetbrains.skia.Gradient
-import org.jetbrains.skia.Paint as SkPaint
-import org.jetbrains.skia.PaintMode
-import org.jetbrains.skia.PaintStrokeCap
-import org.jetbrains.skia.Path as SkPath
-import org.jetbrains.skia.PathBuilder
-import org.jetbrains.skia.Point
-import org.jetbrains.skia.Shader as SkShader
-import org.jetbrains.skia.RRect
-import org.jetbrains.skia.Rect as SkRect
-
-// ==================
-// MARK: SkiaCanvas
-// ==================
-
-/*
- Phase 9 — Skia implementation of `androidx.compose.ui.graphics.Canvas`, mirror of
- `Sdl3Canvas`. Wraps a live `org.jetbrains.skia.Canvas` (from the active
- SkiaBridge — Metal / OpenGL / CPU raster) and translates every upstream draw
- call into a Skia primitive.
-
- Text + painter bridges delegate to SkiaTextRenderer / SkiaImageCache exactly
- like Sdl3Canvas. Gradient brushes are currently solid-color fallback (Skia's
- Shader API takes a Gradient descriptor that we don't build yet).
-*/
-internal class SkiaCanvas(
-	private val fCanvas: SkCanvas,
-	@Suppress("UNUSED_PARAMETER") inSize: Size,
-	private val fTextRenderer: SkiaTextRenderer? = null,
-	private val fImageCache: SkiaImageCache? = null,
-) : Canvas,
-	com.compose.sdl.text.NativeTextCanvas,
-	com.compose.sdl.graphics.NativePainterCanvas,
-	com.compose.sdl.graphics.NativeShadowCanvas {
-
-	fun finish() { /* Skia save/restore is balanced per call */ }
-
-	// ============
-	//  Drop shadow (NativeShadowCanvas) — a real Gaussian blur MaskFilter on
-	//  the layer's outline, offset downward for the spot-light look. Called by
-	//  ProjectOwnedLayer in layer-local coords (canvas already translated).
-
-	override fun drawDropShadow(
-		inOutline: androidx.compose.ui.graphics.Outline,
-		inElevationPx: Float,
-		inAmbientColor: androidx.compose.ui.graphics.Color,
-		inSpotColor: androidx.compose.ui.graphics.Color,
-	) {
-		if (inElevationPx <= 0f) return
-		val vOffsetY = inElevationPx * 0.4f
-		val vPaint = SkPaint().apply {
-			color = toSkiaColor(inSpotColor.copy(alpha = 0.28f * inSpotColor.alpha))
-			maskFilter = org.jetbrains.skia.MaskFilter.makeBlur(
-				org.jetbrains.skia.FilterBlurMode.NORMAL,
-				sigma = inElevationPx * 0.5f + 0.5f,
-			)
-		}
-		when (inOutline) {
-			is androidx.compose.ui.graphics.Outline.Rectangle -> {
-				val vR = inOutline.rect
-				fCanvas.drawRRect(
-					org.jetbrains.skia.RRect.makeLTRB(vR.left, vR.top + vOffsetY, vR.right, vR.bottom + vOffsetY, 0f),
-					vPaint,
-				)
-			}
-			is androidx.compose.ui.graphics.Outline.Rounded -> {
-				val vRr = inOutline.roundRect
-				fCanvas.drawRRect(
-					org.jetbrains.skia.RRect.makeLTRB(
-						vRr.left, vRr.top + vOffsetY, vRr.right, vRr.bottom + vOffsetY,
-						vRr.topLeftCornerRadius.x,
-					),
-					vPaint,
-				)
-			}
-			is androidx.compose.ui.graphics.Outline.Generic -> {
-				// Blur the ACTUAL path — CutCornerShape / GenericShape shadows
-				// follow the real outline instead of the bounding rect.
-				fCanvas.save()
-				fCanvas.translate(0f, vOffsetY)
-				fCanvas.drawPath(toSkiaPath(inOutline.path), vPaint)
-				fCanvas.restore()
-			}
-		}
-		vPaint.close()
-	}
-
-	// ============
-	//  Transform / clip state — delegated to Skia's own stack.
-
-	override fun save() { fCanvas.save() }
-	override fun restore() { fCanvas.restore() }
-	override fun saveLayer(bounds: Rect, paint: Paint) {
-		// Ignore caller-computed bounds and pass a huge rect. ProjectOwnedLayer.drawLayer
-		// computes bounds from THIS layer's own fPosition + fTranslation + fSize —
-		// it can't see inner-layer translations that would paint outside those bounds.
-		// Concrete failure: dragging a tab with `graphicsLayer(alpha=0.65f, translationX=X)`
-		// — the layer's saveLayer bounds don't include any subsequent inner-layer
-		// translation, so on Skia GPU backends the offscreen buffer is allocated too
-		// small and the ghost gets clipped as it slides. Even with the single-layer app
-		// fix, Skia's saveLayer(bounds, alphaPaint) allocates an offscreen SIZED to
-		// bounds — passing tight (fPos + fTrans + size) bounds is exactly the layer's
-		// own painted rect, so anything drawn OUTSIDE that rect via child modifiers
-		// (padding overshoot, border stroke overshoot, drop shadow) is trimmed.
-		// A large explicit rect avoids overload resolution ambiguity that `null as
-		// SkRect?` had (didn't seem to hit the null branch consistently). Alpha compositing
-		// still works — Skia does the alpha modulation via layerPaint on restore().
-		// SaveLayer paint carries alpha (for compositing) — no shape geometry, so
-		// pass zero size / origin; the gradient/shader branches don't fire for a
-		// layer paint.
-		val vLayerPaint = toSkiaPaint(paint, Size(0f, 0f), Offset.Zero)
-		fCanvas.saveLayer(-100_000f, -100_000f, 100_000f, 100_000f, vLayerPaint)
-		vLayerPaint.close()
-	}
-	override fun translate(dx: Float, dy: Float) { fCanvas.translate(dx, dy) }
-	override fun scale(sx: Float, sy: Float) { fCanvas.scale(sx, sy) }
-	override fun rotate(degrees: Float) { fCanvas.rotate(degrees) }
-	override fun skew(sx: Float, sy: Float) { fCanvas.skew(sx, sy) }
-	override fun concat(matrix: Matrix) {
-		val vM = org.jetbrains.skia.Matrix33(
-			matrix.values[0], matrix.values[4], matrix.values[12],
-			matrix.values[1], matrix.values[5], matrix.values[13],
-			matrix.values[3], matrix.values[7], matrix.values[15],
-		)
-		fCanvas.concat(vM)
-	}
-
-	override fun clipRect(left: Float, top: Float, right: Float, bottom: Float, clipOp: ClipOp) {
-		fCanvas.clipRect(
-			SkRect.makeLTRB(left, top, right, bottom),
-			if (clipOp == ClipOp.Difference) ClipMode.DIFFERENCE else ClipMode.INTERSECT,
-			true,
-		)
-	}
-
-	override fun clipPath(path: ComposePath, clipOp: ClipOp) {
-		fCanvas.clipPath(
-			toSkiaPath(path),
-			if (clipOp == ClipOp.Difference) ClipMode.DIFFERENCE else ClipMode.INTERSECT,
-			true,
-		)
-	}
-
-	// ============
-	//  Draw primitives.
-
-	override fun drawRect(left: Float, top: Float, right: Float, bottom: Float, paint: Paint) {
-		val vSize = Size(right - left, bottom - top)
-		val vSk = toSkiaPaint(paint, vSize, Offset(left, top))
-		fCanvas.drawRect(SkRect.makeLTRB(left, top, right, bottom), vSk)
-		vSk.close()
-	}
-
-	override fun drawRoundRect(
-		left: Float, top: Float, right: Float, bottom: Float,
-		radiusX: Float, radiusY: Float, paint: Paint,
-	) {
-		val vSize = Size(right - left, bottom - top)
-		val vSk = toSkiaPaint(paint, vSize, Offset(left, top))
-		fCanvas.drawRRect(
-			RRect.makeLTRB(left, top, right, bottom, radiusX, radiusY),
-			vSk,
-		)
-		vSk.close()
-	}
-
-	override fun drawOval(left: Float, top: Float, right: Float, bottom: Float, paint: Paint) {
-		val vSize = Size(right - left, bottom - top)
-		val vSk = toSkiaPaint(paint, vSize, Offset(left, top))
-		fCanvas.drawOval(SkRect.makeLTRB(left, top, right, bottom), vSk)
-		vSk.close()
-	}
-
-	override fun drawCircle(center: Offset, radius: Float, paint: Paint) {
-		val vSize = Size(radius * 2f, radius * 2f)
-		val vSk = toSkiaPaint(paint, vSize, Offset(center.x - radius, center.y - radius))
-		fCanvas.drawCircle(center.x, center.y, radius, vSk)
-		vSk.close()
-	}
-
-	override fun drawArc(
-		left: Float, top: Float, right: Float, bottom: Float,
-		startAngle: Float, sweepAngle: Float, useCenter: Boolean, paint: Paint,
-	) {
-		val vSize = Size(right - left, bottom - top)
-		val vSk = toSkiaPaint(paint, vSize, Offset(left, top))
-		fCanvas.drawArc(left, top, right, bottom, startAngle, sweepAngle, useCenter, vSk)
-		vSk.close()
-	}
-
-	override fun drawLine(p1: Offset, p2: Offset, paint: Paint) {
-		val vSk = toSkiaPaint(paint, Size(0f, 0f), Offset.Zero)
-		fCanvas.drawLine(p1.x, p1.y, p2.x, p2.y, vSk)
-		vSk.close()
-	}
-
-	override fun drawPath(path: ComposePath, paint: Paint) {
-		val vSk = toSkiaPaint(paint, Size(0f, 0f), Offset.Zero)
-		fCanvas.drawPath(toSkiaPath(path), vSk)
-		vSk.close()
-	}
-	// ============
-	//  Native bridges.
-
-	override fun drawNativeText(
-		inText: String,
-		inSpans: List<androidx.compose.ui.text.AnnotatedString.Range<androidx.compose.ui.text.SpanStyle>>?,
-		inX: Float,
-		inY: Float,
-		inBoxWidth: Float,
-		inBoxHeight: Float,
-		inColor: ComposeColor,
-		inFontSizePx: Int,
-		inTextAlign: androidx.compose.ui.text.style.TextAlign,
-		inSoftWrap: Boolean,
-		inFontFamily: String?,
-		inFontVariations: List<androidx.compose.ui.text.font.FontVariation.Setting>?,
-		inBaseItalic: Boolean,
-		inTextDecoration: androidx.compose.ui.text.style.TextDecoration?,
-	) {
-		val vUnderline = inTextDecoration?.contains(androidx.compose.ui.text.style.TextDecoration.Underline) == true
-		val vLineThrough = inTextDecoration?.contains(androidx.compose.ui.text.style.TextDecoration.LineThrough) == true
-		fTextRenderer?.drawText(
-			inCanvas = fCanvas,
-			inText = inText,
-			inX = inX,
-			inY = inY,
-			inBoxWidth = inBoxWidth.toInt(),
-			inBoxHeight = inBoxHeight.toInt(),
-			inColor = inColor,
-			inFontSize = inFontSizePx,
-			inAlign = inTextAlign,
-			inSoftWrap = inSoftWrap,
-			inFontFamily = inFontFamily,
-			inFontVariations = inFontVariations,
-			inSpans = inSpans,
-			inBaseItalic = inBaseItalic,
-			inBaseUnderline = vUnderline,
-			inBaseLineThrough = vLineThrough,
-		)
-	}
-
-	override fun drawNativePainter(
-		inResourcePath: String,
-		inKind: com.compose.sdl.res.ResourceKind,
-		inX: Float,
-		inY: Float,
-		inWidth: Float,
-		inHeight: Float,
-		inContentScale: androidx.compose.ui.layout.ContentScale,
-		inAlpha: Float,
-	) {
-		fImageCache?.draw(
-			inCanvas = fCanvas,
-			inPath = inResourcePath,
-			inKind = inKind,
-			inX = inX,
-			inY = inY,
-			inW = inWidth,
-			inH = inHeight,
-			inScale = inContentScale,
-			inAlpha = inAlpha,
-		)
-	}
-
-	// ============
-	//  Native image (ImageBitmap-backed vector — see SkiaOffscreen). The offscreen
-	//  registers itself lazily, so anything not backed by a SkiaImageBitmap surface
-	//  (a hypothetical stub) is silently skipped.
-
-	override fun drawImage(image: ImageBitmap, topLeftOffset: Offset, paint: Paint) {
-		val vBmp = image as? SkiaImageBitmap ?: return
-		val vImg = vBmp.snapshot()
-		val vSkPaint = imageBlitPaint(paint)
-		fCanvas.drawImage(vImg, topLeftOffset.x, topLeftOffset.y, vSkPaint)
-		vSkPaint.close()
-	}
-
-	override fun drawImageRect(
-		image: ImageBitmap,
-		srcOffset: androidx.compose.ui.unit.IntOffset,
-		srcSize: androidx.compose.ui.unit.IntSize,
-		dstOffset: androidx.compose.ui.unit.IntOffset,
-		dstSize: androidx.compose.ui.unit.IntSize,
-		paint: Paint,
-	) {
-		val vBmp = image as? SkiaImageBitmap ?: return
-		val vImg = vBmp.snapshot()
-		val vSrc = SkRect.makeXYWH(
-			srcOffset.x.toFloat(), srcOffset.y.toFloat(),
-			srcSize.width.toFloat(), srcSize.height.toFloat(),
-		)
-		val vDst = SkRect.makeXYWH(
-			dstOffset.x.toFloat(), dstOffset.y.toFloat(),
-			dstSize.width.toFloat(), dstSize.height.toFloat(),
-		)
-		val vSkPaint = imageBlitPaint(paint)
-		fCanvas.drawImageRect(vImg, vSrc, vDst, vSkPaint, true)
-		vSkPaint.close()
-	}
-
-	// Blit paint: alpha modulated as the paint colour's alpha; ColorFilter (Icon
-	// tint arrives here) forwarded to Skia so the vendored VectorPainter's
-	// ColorFilter.tint recolours the icon at composite time.
-	private fun imageBlitPaint(inPaint: Paint): SkPaint {
-		val vP = SkPaint()
-		vP.color = SkColor.makeARGB(
-			(inPaint.alpha * 255f).toInt().coerceIn(0, 255), 255, 255, 255,
-		)
-		vP.isAntiAlias = true
-		inPaint.colorFilter?.let {
-			vP.colorFilter = it.asSkiaColorFilter()
-		}
-		return vP
-	}
-
-	override fun drawPoints(pointMode: PointMode, points: List<Offset>, paint: Paint) {}
-	override fun drawRawPoints(pointMode: PointMode, points: FloatArray, paint: Paint) {}
-	override fun drawVertices(vertices: Vertices, blendMode: BlendMode, paint: Paint) {}
-	override fun enableZ() {}
-	override fun disableZ() {}
-
-	// ============
-	//  Paint translation. Recovers a gradient Brush stashed on paint.shader (see
-	//  CanvasPaintActuals.native.kt — ShaderBrush.applyTo drops everything but
-	//  color=Black otherwise) and builds the matching Skia Shader, using the
-	//  shape's [inShapeSize] to resolve infinite-anchor gradients. Forwards
-	//  paint.colorFilter and paint.blendMode (BlendMode.Clear zeroes the region,
-	//  which DrawCache relies on to clear the offscreen before rasterising a
-	//  vector).
-
-	private fun toSkiaPaint(inPaint: Paint, inShapeSize: Size, inShapeOrigin: Offset): SkPaint {
-		val vPaint = SkPaint()
-		vPaint.isAntiAlias = true
-		vPaint.mode = if (inPaint.style == PaintingStyle.Stroke) PaintMode.STROKE else PaintMode.FILL
-		vPaint.strokeWidth = inPaint.strokeWidth
-		vPaint.strokeCap = when (inPaint.strokeCap) {
-			ComposeStrokeCap.Round -> PaintStrokeCap.ROUND
-			ComposeStrokeCap.Square -> PaintStrokeCap.SQUARE
-			else -> PaintStrokeCap.BUTT
-		}
-		val vBrush = inPaint.shader?.brush
-		val vBaseColor = SkColor.makeARGB(
-			(inPaint.color.alpha * inPaint.alpha * 255f).toInt().coerceIn(0, 255),
-			(inPaint.color.red * 255f).toInt().coerceIn(0, 255),
-			(inPaint.color.green * 255f).toInt().coerceIn(0, 255),
-			(inPaint.color.blue * 255f).toInt().coerceIn(0, 255),
-		)
-		when (vBrush) {
-			null, is SolidColor -> {
-				vPaint.color = vBaseColor
-			}
-			is LinearGradient -> {
-				vPaint.color = whiteAlpha(inPaint.alpha)
-				vPaint.shader = makeLinearShader(vBrush, inShapeSize, inShapeOrigin)
-			}
-			is RadialGradient -> {
-				vPaint.color = whiteAlpha(inPaint.alpha)
-				vPaint.shader = makeRadialShader(vBrush, inShapeSize, inShapeOrigin)
-			}
-			is SweepGradient -> {
-				vPaint.color = whiteAlpha(inPaint.alpha)
-				vPaint.shader = makeSweepShader(vBrush, inShapeSize, inShapeOrigin)
-			}
-			else -> {
-				vPaint.color = vBaseColor
-			}
-		}
-		inPaint.colorFilter?.let { vPaint.colorFilter = it.asSkiaColorFilter() }
-		vPaint.blendMode = inPaint.blendMode.toSkia()
-		return vPaint
-	}
-
-	private fun whiteAlpha(inAlpha: Float): Int =
-		SkColor.makeARGB((inAlpha * 255f).toInt().coerceIn(0, 255), 255, 255, 255)
-
-	private fun makeLinearShader(inB: LinearGradient, inSize: Size, inOrigin: Offset): SkShader {
-		val vSx = inOrigin.x + resolveX(inB.gradientStart.x, inSize.width)
-		val vSy = inOrigin.y + resolveY(inB.gradientStart.y, inSize.height)
-		val vEx = inOrigin.x + resolveX(inB.gradientEnd.x, inSize.width)
-		val vEy = inOrigin.y + resolveY(inB.gradientEnd.y, inSize.height)
-		return SkShader.makeLinearGradient(
-			p0 = Point(vSx, vSy),
-			p1 = Point(vEx, vEy),
-			gradient = Gradient(skiaColorsFor(inB.gradientColors, inB.gradientStops, inB.gradientTileMode.toSkia())),
-		)
-	}
-
-	private fun makeRadialShader(inB: RadialGradient, inSize: Size, inOrigin: Offset): SkShader {
-		val vCx = inOrigin.x + resolveX(inB.gradientCenter.x, inSize.width)
-		val vCy = inOrigin.y + resolveY(inB.gradientCenter.y, inSize.height)
-		val vR = if (inB.gradientRadius.isFinite()) inB.gradientRadius else (inSize.minDimension / 2f)
-		return SkShader.makeRadialGradient(
-			center = Point(vCx, vCy),
-			radius = vR,
-			gradient = Gradient(skiaColorsFor(inB.gradientColors, inB.gradientStops, inB.gradientTileMode.toSkia())),
-		)
-	}
-
-	private fun makeSweepShader(inB: SweepGradient, inSize: Size, inOrigin: Offset): SkShader {
-		val vCx = inOrigin.x + resolveX(inB.gradientCenter.x, inSize.width)
-		val vCy = inOrigin.y + resolveY(inB.gradientCenter.y, inSize.height)
-		return SkShader.makeSweepGradient(
-			center = Point(vCx, vCy),
-			gradient = Gradient(skiaColorsFor(inB.gradientColors, inB.gradientStops, FilterTileMode.CLAMP)),
-		)
-	}
-
-	private fun skiaColorsFor(
-		inColors: List<ComposeColor>,
-		inStops: List<Float>?,
-		inTile: FilterTileMode,
-	): Gradient.Colors = Gradient.Colors(
-		colors = Array(inColors.size) { Color4f(r = inColors[it].r8 / 255f, g = inColors[it].g8 / 255f, b = inColors[it].b8 / 255f, a = inColors[it].a8 / 255f) },
-		positions = inStops?.toFloatArray(),
-		tileMode = inTile,
-	)
-
-	private fun resolveX(inV: Float, inW: Float): Float = if (inV.isFinite()) inV else inW
-	private fun resolveY(inV: Float, inH: Float): Float = if (inV.isFinite()) inV else inH
-
-	private fun ComposeTileMode.toSkia(): FilterTileMode = when (this) {
-		ComposeTileMode.Clamp    -> FilterTileMode.CLAMP
-		ComposeTileMode.Repeated -> FilterTileMode.REPEAT
-		ComposeTileMode.Mirror   -> FilterTileMode.MIRROR
-		ComposeTileMode.Decal    -> FilterTileMode.DECAL
-		else                     -> FilterTileMode.CLAMP
-	}
-
-	// ============
-	//  Path translation. Two possible source types since our skikoRenderer source
-	//  set inherits BOTH the commonMain `ProjectPath` and the vendored
-	//  `SkiaBackedPath` (`actual fun Path(): Path = SkiaBackedPath()` lives in
-	//  vendor/skikoRenderer/…/SkiaBackedPath.skiko.kt). Upstream callers that build
-	//  a Path via `Path()` — including `MultiParagraph.getPathForRange`, which
-	//  drives text-selection highlight rendering — get a SkiaBackedPath. Our own
-	//  `ProjectPath` still surfaces from code paths that build via
-	//  `com.compose.sdl.graphics.ProjectPath()` directly. Try
-	//  SkiaBackedPath's own Skia handle first (zero-copy, avoids replaying a
-	//  command list); otherwise, replay ProjectPath's commands.
-	//
-	//  Regression that motivated the branch: selection highlight painted an empty
-	//  Skia path — the SkiaBackedPath fell through the `as? ProjectPath` check and
-	//  returned an empty PathBuilder snapshot.
-
-	private fun toSkiaPath(inPath: ComposePath): SkPath {
-		(inPath as? SkiaBackedPath)?.let { return (it as ComposePath).asSkiaPath() }
-		val vB = PathBuilder()
-		val vCommands = (inPath as? ProjectPath)?.commands ?: return vB.snapshot().also { vB.close() }
-		for (vCmd in vCommands) when (vCmd) {
-			is PathCommand.MoveTo -> vB.moveTo(vCmd.x, vCmd.y)
-			is PathCommand.LineTo -> vB.lineTo(vCmd.x, vCmd.y)
-			is PathCommand.QuadTo -> vB.quadTo(vCmd.cx, vCmd.cy, vCmd.x, vCmd.y)
-			is PathCommand.CubicTo -> vB.cubicTo(vCmd.c1x, vCmd.c1y, vCmd.c2x, vCmd.c2y, vCmd.x, vCmd.y)
-			PathCommand.Close -> vB.closePath()
-		}
-		return vB.snapshot().also { vB.close() }
-	}
-}

compose/ui/ui/src/skikoRendererMain/kotlin/com/compose/sdl/renderer/skia/SkiaLeafDrawer.kt

@@ -0,0 +1,20 @@
+package com.compose.sdl.renderer.skia
+
+// ==================
+// MARK: SkiaLeafDrawer — port text/image renderers behind the upstream canvas (B6.1)
+// ==================
+
+/* The Skia leg draws through upstream's `SkiaBackedCanvas` (real gradients/paint/
+   shader), but keeps the port's text engine (`SkiaTextRenderer`, incl. the P3.1
+   metric work) and resource-image cache (`SkiaImageCache`). `SkiaBackedCanvas` is
+   manual-vendored to implement the port `NativeTextCanvas`/`NativePainterCanvas`
+   contracts and forwards to this drawer, which holds the two long-lived renderers
+   the way the old per-frame `SkiaCanvas` used to. Set once by `SkiaRenderBackend`;
+   any `SkiaBackedCanvas` (frame, offscreen, or a GraphicsLayer recording — B6.2)
+   can then draw text/images onto its own `internalSkiaCanvas`. */
+internal var skiaLeafDrawer: SkiaLeafDrawer? = null
+
+internal class SkiaLeafDrawer(
+	val textRenderer: SkiaTextRenderer,
+	val imageCache: SkiaImageCache,
+)

compose/ui/ui/src/skikoRendererMain/kotlin/com/compose/sdl/renderer/skia/SkiaOffscreen.kt

@@ -1,93 +1,9 @@
 package com.compose.sdl.renderer.skia
 
-import androidx.compose.ui.geometry.Size
-import androidx.compose.ui.graphics.Canvas
 import androidx.compose.ui.graphics.ImageBitmap
-import androidx.compose.ui.graphics.ImageBitmapConfig
-import androidx.compose.ui.graphics.colorspace.ColorSpace
-import androidx.compose.ui.graphics.colorspace.ColorSpaces
+import androidx.compose.ui.graphics.toComposeImageBitmap
 import com.compose.sdl.graphics.EncodedImageDecoder
-import com.compose.sdl.graphics.OffscreenRenderer
 import org.jetbrains.skia.Image
-import org.jetbrains.skia.Surface
-
-// ==================
-// MARK: Skia offscreen bitmap support
-// ==================
-
-// An ImageBitmap backed by a Skia Surface. The vector rasterises INTO the
-// surface (via a Canvas returned by the factory) and SkiaCanvas.drawImageRect
-// blits it back — with an Icon's tint applied through the paint's ColorFilter.
-// prepareToDraw() invalidates the cached snapshot so the next blit re-samples
-// the freshly-drawn surface.
-internal class SkiaImageBitmap(
-	override val width: Int,
-	override val height: Int,
-	override val config: ImageBitmapConfig,
-	override val hasAlpha: Boolean,
-	override val colorSpace: ColorSpace,
-) : ImageBitmap {
-
-	// Raster (CPU) surface: matches SkiaImageCache.rasterizeSvg's pattern and
-	// works on every SkiaBridge (Metal / OpenGL / software raster). Icon-sized
-	// vectors are tiny; a GPU surface would need a shared GrContext with the
-	// active bridge which Skiko doesn't expose portably here.
-	val surface: Surface = Surface.makeRasterN32Premul(width.coerceAtLeast(1), height.coerceAtLeast(1))
-
-	// Cached snapshot of the surface pixels. Cleared by prepareToDraw() so a
-	// re-rasterised vector reuploads on the next blit; retained across frames
-	// when the vector doesn't change.
-	private var fSnapshot: Image? = null
-
-	fun snapshot(): Image {
-		val vExisting = fSnapshot
-		if (vExisting != null) return vExisting
-		val vFresh = surface.makeImageSnapshot()
-		fSnapshot = vFresh
-		return vFresh
-	}
-
-	override fun readPixels(
-		buffer: IntArray,
-		startX: Int,
-		startY: Int,
-		width: Int,
-		height: Int,
-		bufferOffset: Int,
-		stride: Int,
-	) {
-	}
-
-	override fun prepareToDraw() {
-		fSnapshot?.close()
-		fSnapshot = null
-	}
-}
-
-// Registered on SkiaRenderBackend; hands the vendored DrawCache a real offscreen.
-internal class SkiaOffscreenRenderer(
-	private val fTextRenderer: SkiaTextRenderer?,
-	private val fImageCache: SkiaImageCache?,
-) : OffscreenRenderer {
-
-	override fun createImageBitmap(
-		width: Int,
-		height: Int,
-		config: ImageBitmapConfig,
-		hasAlpha: Boolean,
-		colorSpace: ColorSpace,
-	): ImageBitmap = SkiaImageBitmap(width, height, config, hasAlpha, colorSpace)
-
-	override fun createCanvas(image: ImageBitmap): Canvas? {
-		val vBmp = image as? SkiaImageBitmap ?: return null
-		return SkiaCanvas(
-			vBmp.surface.canvas,
-			Size(vBmp.width.toFloat(), vBmp.height.toFloat()),
-			fTextRenderer,
-			fImageCache,
-		)
-	}
-}
 
 // ==================
 // MARK: SkiaEncodedImageDecoder
@@ -98,7 +14,12 @@ internal class SkiaOffscreenRenderer(
    (painterResource / SVG). Raster formats go through Image.makeFromEncoded;
    when that fails the bytes are retried as SVG through the same SVGDOM
    rasterisation SkiaImageCache uses. Pure CPU raster (no GrContext), so it is
-   safe on the resources pipeline's Dispatchers.Default workers. */
+   safe on the resources pipeline's Dispatchers.Default workers.
+
+   B6.1: produces an UPSTREAM ImageBitmap (Image.toComposeImageBitmap) — the Skia
+   leg now uses upstream's SkiaBackedCanvas/SkiaImageAsset, so the offscreen +
+   ImageBitmap-backed paths go through upstream's own actuals (the project
+   SkiaImageBitmap / SkiaOffscreenRenderer are retired). */
 internal class SkiaEncodedImageDecoder : EncodedImageDecoder {
 
 	override fun decode(inBytes: ByteArray): ImageBitmap? {
@@ -106,13 +27,7 @@ internal class SkiaEncodedImageDecoder : EncodedImageDecoder {
 		val vImg = runCatching { Image.makeFromEncoded(inBytes) }.getOrNull()
 			?: rasterizeSvg(inBytes)
 			?: return null
-		val vBmp = SkiaImageBitmap(
-			vImg.width, vImg.height,
-			config = ImageBitmapConfig.Argb8888,
-			hasAlpha = true,
-			colorSpace = ColorSpaces.Srgb,
-		)
-		vBmp.surface.canvas.drawImage(vImg, 0f, 0f)
+		val vBmp = vImg.toComposeImageBitmap()
 		vImg.close()
 		return vBmp
 	}

compose/ui/ui/src/skikoRendererMain/kotlin/com/compose/sdl/renderer/skia/SkiaRenderBackend.kt

@@ -5,6 +5,7 @@ import com.compose.sdl.res.ImageLoader
 import com.compose.sdl.res.ResourceKind
 import com.compose.sdl.text.TextMeasurer
 import com.compose.sdl.*
+import androidx.compose.ui.graphics.asComposeCanvas
 import org.jetbrains.skia.Canvas
 import org.jetbrains.skia.Color as SkColor
 
@@ -19,10 +20,10 @@ import org.jetbrains.skia.Color as SkColor
    AUTO is resolved at the call site (ComposeWindow); this class only
    sees concrete modes.
 
-   NOTE: Phase 9 pivoted rendering to the upstream engine via drawRoot(host).
-   A real SkiaCanvas : androidx.compose.ui.graphics.Canvas actual is TODO —
-   until then the Skia path compiles but paints nothing (drawRoot inherits
-   the RenderBackend default no-op). */
+   B6.1: the composition draws through upstream's SkiaBackedCanvas (real
+   paint/shader/gradients). The port's text engine (SkiaTextRenderer) +
+   resource-image cache (SkiaImageCache) + elevation shadows ride behind it
+   via skiaLeafDrawer + the SkiaBackedCanvas manual-vendor. */
 internal class SkiaRenderBackend(
     private val sdl: SDL3Backend,
     private val gpuMode: GpuMode,
@@ -45,6 +46,15 @@ internal class SkiaRenderBackend(
         }
     }
 
+    // B6.1: the Skia leg draws through upstream SkiaBackedCanvas; its port draw
+    // contracts (text/painter/shadow) forward to the port renderers via this global
+    // drawer. It is per-WINDOW state (each window has its own text renderer + image
+    // cache), so it must be re-pointed at THIS backend before every frame — exactly
+    // like ComposeWindow.installGlobals() does for currentTextMeasurer. Setting it
+    // once in the ctor left it dangling at a CLOSED window's (destroyed) renderer
+    // after a multi-window teardown → crash on the surviving window's next frame.
+    private val fLeafDrawer = SkiaLeafDrawer(fSkiaTextRenderer, fSkiaImageCache)
+
     override val textMeasurer: TextMeasurer
         get() = fSkiaTextRenderer.textMeasurer
 
@@ -69,10 +79,8 @@ internal class SkiaRenderBackend(
     override fun beginFrame(inDpr: Float) {
         val canvas = fBridge.canvas
         // Clear the surface to Material dark. Without this the Metal back
-        // buffer shows uninitialized GPU memory (pink) since Sdl3Renderer.draw
-        // no longer runs and drawRoot is a no-op inherited default until
-        // SkiaCanvas lands. Clearing before scale so it covers the whole
-        // physical target.
+        // buffer shows uninitialized GPU memory (pink). Clearing before scale
+        // so it covers the whole physical target.
         canvas.clear(SkColor.makeARGB(0xFF, 0x12, 0x12, 0x12))
         canvas.save()
         if (inDpr != 1f) canvas.scale(inDpr, inDpr)
@@ -86,19 +94,17 @@ internal class SkiaRenderBackend(
         fCurrentCanvas = canvas
     }
 
-    override fun drawRoot(inHost: com.compose.sdl.node.ComposeRootHost) {
+    override fun drawRoot(inDraw: (androidx.compose.ui.graphics.Canvas) -> Unit) {
         val canvas = fCurrentCanvas ?: return
-        // Register the offscreen (ImageBitmap) render path so the vendored
-        // VectorPainter / DrawCache pipeline — hence material3's ImageVector
-        // icons — renders. Idempotent.
-        if (com.compose.sdl.graphics.offscreenRenderer == null) {
-            com.compose.sdl.graphics.offscreenRenderer =
-                SkiaOffscreenRenderer(fSkiaTextRenderer, fSkiaImageCache)
-        }
-        val vSize = androidx.compose.ui.geometry.Size(sdl.pixelWidth.toFloat(), sdl.pixelHeight.toFloat())
-        val vCanvas = SkiaCanvas(canvas, vSize, fSkiaTextRenderer, fSkiaImageCache)
-        inHost.rootNode.draw(vCanvas, null)
-        vCanvas.finish()
+        // Point the leaf-draw global at THIS window's renderers before drawing.
+        skiaLeafDrawer = fLeafDrawer
+        // Wrap the live skia canvas as upstream's SkiaBackedCanvas (real gradients/
+        // paint/shader). Its port draw contracts forward to skiaLeafDrawer. The
+        // ImageBitmap-backed offscreen (VectorPainter / DrawCache) now goes through
+        // upstream's own ActualCanvas, so no project offscreenRenderer registration.
+        val vCanvas = canvas.asComposeCanvas()
+        inDraw(vCanvas)
+        (vCanvas as? com.compose.sdl.graphics.NativeFinishableCanvas)?.finish()
     }
 
     override fun endFrame() {
@@ -110,6 +116,9 @@ internal class SkiaRenderBackend(
     override fun snapshotBgra(): Triple<Int, Int, ByteArray>? = fBridge.snapshotBgra()
 
     override fun destroy() {
+        // Drop the global if it still points at this (about-to-be-destroyed) backend,
+        // so a stray draw before the next window's drawRoot can't hit freed renderers.
+        if (skiaLeafDrawer === fLeafDrawer) skiaLeafDrawer = null
         fSkiaImageCache.destroy()
         fSkiaTextRenderer.destroy()
         fBridge.destroy()

compose/ui/ui/src/skikoRendererMain/kotlin/com/compose/sdl/renderer/skia/SkiaTextRenderer.kt

@@ -163,11 +163,22 @@ class SkiaTextRenderer {
         inBaseItalic: Boolean = false,
         inBaseUnderline: Boolean = false,
         inBaseLineThrough: Boolean = false,
+        // The paragraph's per-line band (TextStyle.lineHeight) in px — stack lines at
+        // the same advance layout used. <= 0 → font-metrics height (legacy callers).
+        inLineHeightPx: Float = 0f,
+        // Compat-trim (raw styles): the first line keeps the tight font cell. False for
+        // M3's LineHeightStyle(Trim.None) — every line is the full band.
+        inTrimFirstLine: Boolean = true,
     ) {
         val vKey = TypefaceKey(inFontFamily, variationsKey(inFontVariations))
         val vBaseFont = getFont(vKey, inFontFamily, inFontVariations, inFontSize)
         val vBaseMetrics = vBaseFont.metrics
-        val vBaseLineHeight = (vBaseMetrics.descent - vBaseMetrics.ascent).coerceAtLeast(1f)
+        // Per-mode stacking (mirrors SdlParagraph): compat trim keeps the FIRST line at
+        // the tight font cell; M3's Trim.None makes every line the full band. Following
+        // lines advance by the band (inLineHeightPx) when supplied, else the font cell.
+        val vFontCellH = (vBaseMetrics.descent - vBaseMetrics.ascent).coerceAtLeast(1f)
+        val vBaseLineHeight = if (inLineHeightPx > 0f) inLineHeightPx else vFontCellH
+        val vFirstLineH = if (inTrimFirstLine || inLineHeightPx <= 0f) vFontCellH else vBaseLineHeight
         val vCapHeight = if (vBaseMetrics.capHeight > 0f) vBaseMetrics.capHeight
                          else inFontSize * 0.7f
 
@@ -191,9 +202,10 @@ class SkiaTextRenderer {
                 inCanvas.drawString(expandTabs(vLines[0]), vPenX, vBaseline, vBaseFont, vFastPaint)
             } else {
                 for ((vIdx, vLine) in vLines.withIndex()) {
-                    val vSlotTop = inY + vIdx * vBaseLineHeight
-                    if (vSlotTop + vBaseLineHeight < inViewTop || vSlotTop > inViewBottom) continue
-                    val vBaseline = vSlotTop + (vBaseLineHeight + vCapHeight) / 2f
+                    val vSlotH = if (vIdx == 0) vFirstLineH else vBaseLineHeight
+                    val vSlotTop = inY + (if (vIdx == 0) 0f else vFirstLineH + (vIdx - 1) * vBaseLineHeight)
+                    if (vSlotTop + vSlotH < inViewTop || vSlotTop > inViewBottom) continue
+                    val vBaseline = vSlotTop + (vSlotH + vCapHeight) / 2f
                     val vPenX = alignX(inX, inBoxWidth, estimateTextWidth(vLine, inFontSize, inFontFamily, inFontVariations).toFloat(), inAlign)
                     inCanvas.drawString(expandTabs(vLine), vPenX, vBaseline, vBaseFont, vFastPaint)
                 }
@@ -212,11 +224,14 @@ class SkiaTextRenderer {
             val vLineStart = vWrapped.lineStarts.getOrElse(vIdx) { 0 }
             val vLineH =
                 if (vMetricSpans && inSpans != null) {
-                    styledLineCellHeight(
-                        vLine, vLineStart, inSpans, inFontSize, fDensity,
-                        textMeasurer, inFontFamily, inFontVariations,
+                    kotlin.math.max(
+                        styledLineCellHeight(
+                            vLine, vLineStart, inSpans, inFontSize, fDensity,
+                            textMeasurer, inFontFamily, inFontVariations,
+                        ),
+                        if ((vIdx == 0 && inTrimFirstLine) || inLineHeightPx <= 0f) 0f else inLineHeightPx,
                     ).coerceAtLeast(1f)
-                } else vBaseLineHeight
+                } else if (vIdx == 0) vFirstLineH else vBaseLineHeight
             if (vLineY + vLineH < inViewTop || vLineY > inViewBottom) {
                 vLineY += vLineH
                 continue

demo/build.gradle.kts

@@ -13,15 +13,15 @@ plugins {
 // Skip mingwX64 on non-Windows hosts; see root build.gradle.kts.
 val vHostSupportsMingw = rootProject.extra["vHostSupportsMingw"] as Boolean
 
-// JVM parity target's Compose version — the dev build matching the pinned
+// JVM parity target's Compose version — the Maven build matching the pinned
 // COMPOSE_CORE_REF (see scripts/compose-fork/compose.properties). material3
-// rides its OWN release train: same +dev build number, different base
-// version. Gradle orders "+dev" qualifiers BELOW the plain version, so
-// currentOs's beta01 would win conflict resolution — force the core-repo
-// groups on every jvm configuration. Umbrella-repo groups (desktop,
-// components) are NOT forced: their dev numbering differs.
-val vComposeJvmVersion = "1.12.0-beta01+dev4324"
-val vComposeM3JvmVersion = "1.12.0-alpha03+dev4324"
+// rides its OWN release train (different base version). Forcing keeps the
+// core-repo groups locked to the pin on every jvm configuration even when
+// the umbrella plugin's own version would win conflict resolution (essential
+// for "+dev" pins, which Gradle orders BELOW the plain version). Umbrella-repo
+// groups (desktop, components) are NOT forced: their versioning differs.
+val vComposeJvmVersion = libs.versions.compose.get()
+val vComposeM3JvmVersion = libs.versions.composeMaterial3.get()
 val vComposeJvmForced = mapOf(
     "org.jetbrains.compose.runtime" to vComposeJvmVersion,
     "org.jetbrains.compose.ui" to vComposeJvmVersion,
@@ -111,7 +111,7 @@ kotlin {
                 // visibility check. The runtime is the official klib
                 // everywhere, never substituted (jvm configs force the +dev
                 // build above).
-                implementation("org.jetbrains.compose.runtime:runtime:1.11.1")
+                implementation("org.jetbrains.compose.runtime:runtime:${libs.versions.composeRuntime.get()}")
                 implementation("org.jetbrains.compose.ui:ui:$vComposeJvmVersion")
                 implementation("org.jetbrains.compose.ui:ui-graphics:$vComposeJvmVersion")
                 implementation("org.jetbrains.compose.ui:ui-text:$vComposeJvmVersion")
@@ -309,4 +309,10 @@ tasks.named<ProcessResources>("jvmProcessResources") {
         from(vFontFile) { into("font") }
         dependsOn(vDownloadTask)
     }
+    // P0.3 (RENDERER.md §8): stage the SAME default font the native leg bundles
+    // (data.kres font/NotoSans.ttf) onto the JVM classpath, so the parity harness's JVM leg
+    // renders text with NotoSans too — collapsing the font-drift baseline to (near) just
+    // rasterizer AA. MainJvm loads it from /font/NotoSans.ttf.
+    from(notoSansFile) { into("font") }
+    dependsOn(":ui:downloadNotoFonts")
 }

demo/src/appleMain/kotlin/SoakRss.apple.kt

@@ -0,0 +1,18 @@
+import kotlinx.cinterop.ExperimentalForeignApi
+import kotlinx.cinterop.allocArray
+import kotlinx.cinterop.memScoped
+import kotlinx.cinterop.toKString
+
+// Current resident set (MB) via `ps -o rss=` (KB). See currentResidentMb in MainNative.kt.
+@OptIn(ExperimentalForeignApi::class)
+internal actual fun currentResidentMb(): Long {
+    val vPid = platform.posix.getpid()
+    val vFp = platform.posix.popen("ps -o rss= -p $vPid", "r") ?: return -1
+    val vKb = memScoped {
+        val vBuf = allocArray<kotlinx.cinterop.ByteVar>(64)
+        val vLine = platform.posix.fgets(vBuf, 64, vFp)?.toKString()?.trim()
+        vLine?.toLongOrNull() ?: -1L
+    }
+    platform.posix.pclose(vFp)
+    return if (vKb < 0) -1 else vKb / 1024
+}

demo/src/jvmMain/kotlin/MainJvm.kt

@@ -4,14 +4,20 @@ import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.verticalScroll
+import androidx.compose.material3.LocalTextStyle
 import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Typography
 import androidx.compose.material3.darkColorScheme
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.platform.Font
 import androidx.compose.ui.ExperimentalComposeUiApi
 import androidx.compose.ui.ImageComposeScene
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.Density
 import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
 import androidx.compose.ui.window.Window
 import androidx.compose.ui.window.application
 import androidx.compose.ui.window.rememberWindowState
@@ -40,6 +46,10 @@ fun main(args: Array<String>) {
         )
         return
     }
+    if (args.any { it == "--metrics" }) {
+        printParagraphMetrics()
+        return
+    }
     application {
         Window(
             onCloseRequest = ::exitApplication,
@@ -56,37 +66,168 @@ fun main(args: Array<String>) {
 private fun Array<String>.intArg(name: String, default: Int): Int =
     firstOrNull { it.startsWith("$name=") }?.substringAfter('=')?.toIntOrNull() ?: default
 
+// P0.5 render-to-quiescence (mirrors the native leg): step a VIRTUAL 60fps clock and
+// re-render while the scene still has invalidations, so entrance animations settle
+// before capture. Infinite animations are CANCELLED via the upstream test
+// InfiniteAnimationPolicy (they freeze at their initial value), so looping screens
+// settle too. The cap only guards never-settling content the policy can't reach.
+private const val FRAME_NANOS = 16_666_667L
+private const val MAX_FRAMES = 300
+
+private object CancelInfiniteAnimations : androidx.compose.ui.platform.InfiniteAnimationPolicy {
+    override suspend fun <R> onInfiniteOperation(block: suspend () -> R): R =
+        throw kotlinx.coroutines.CancellationException("infinite animations disabled for parity screenshots")
+}
+
 /* Render each registered screen headlessly (density 1 to match the native
-   physical-pixel screenshots) and write a PNG per screen. */
+   physical-pixel screenshots) to quiescence and write a PNG per screen. */
 @OptIn(ExperimentalComposeUiApi::class)
 private fun screenshotAllScreens(outDir: File, width: Int, height: Int) {
     outDir.mkdirs()
     val screens = allCategories().flatMap { it.screens }.distinctBy { it.name }
     for (screen in screens) {
-        val scene = ImageComposeScene(width, height, density = Density(1f)) {
+        val scene = ImageComposeScene(
+            width, height, density = Density(1f),
+            coroutineContext = kotlinx.coroutines.Dispatchers.Unconfined + CancelInfiniteAnimations,
+        ) {
             ScreenHost { screen.content() }
         }
         try {
-            val image = scene.render()
+            var nanos = 0L
+            var frames = 0
+            var image = scene.render(nanos)
+            while (scene.hasInvalidations() && frames < MAX_FRAMES) {
+                nanos += FRAME_NANOS
+                image = scene.render(nanos)
+                frames++
+            }
             val png = image.encodeToData(EncodedImageFormat.PNG) ?: continue
             File(outDir, "${screen.name}.png").writeBytes(png.bytes)
+            println("jvm screenshot: ${screen.name} (settled after $frames frame(s))")
         } finally {
             scene.close()
         }
-        println("jvm screenshot: ${screen.name}")
     }
 }
 
-/* Same wrapper as MainNative's --screen path. */
+// P0.3 (RENDERER.md §8): the SAME default font the native leg bundles
+// (font/NotoSans.ttf, staged onto the JVM classpath by jvmProcessResources). Loading it
+// into the parity JVM leg collapses the font-drift baseline to (near) just rasterizer AA —
+// so the parity % measures real divergence, not "different default typeface". Null (→ no
+// alignment, harness still runs) if the resource is missing.
+private val notoSans: FontFamily? by lazy {
+    val bytes = object {}.javaClass.getResourceAsStream("/font/NotoSans.ttf")?.readBytes()
+    if (bytes == null) {
+        println("parity(jvm): /font/NotoSans.ttf not on classpath — font NOT aligned")
+        null
+    } else FontFamily(Font(identity = "NotoSans", data = bytes))
+}
+
+/* A copy of the M3 Typography with every core style forced to [family] (Typography styles
+   carry their own fontFamily, so overriding LocalTextStyle alone wouldn't reach them). */
+private fun notoTypography(family: FontFamily): Typography {
+    val b = Typography()
+    return b.copy(
+        displayLarge = b.displayLarge.copy(fontFamily = family),
+        displayMedium = b.displayMedium.copy(fontFamily = family),
+        displaySmall = b.displaySmall.copy(fontFamily = family),
+        headlineLarge = b.headlineLarge.copy(fontFamily = family),
+        headlineMedium = b.headlineMedium.copy(fontFamily = family),
+        headlineSmall = b.headlineSmall.copy(fontFamily = family),
+        titleLarge = b.titleLarge.copy(fontFamily = family),
+        titleMedium = b.titleMedium.copy(fontFamily = family),
+        titleSmall = b.titleSmall.copy(fontFamily = family),
+        bodyLarge = b.bodyLarge.copy(fontFamily = family),
+        bodyMedium = b.bodyMedium.copy(fontFamily = family),
+        bodySmall = b.bodySmall.copy(fontFamily = family),
+        labelLarge = b.labelLarge.copy(fontFamily = family),
+        labelMedium = b.labelMedium.copy(fontFamily = family),
+        labelSmall = b.labelSmall.copy(fontFamily = family),
+    )
+}
+
+/* Upstream-Paragraph metrics for a font-size sweep at density 1 (NotoSans — the same
+   font the native leg bundles). The JVM half of the metrics-alignment probe: MainNative's
+   `--metricsprobe` prints the same table from SdlParagraph; aligning the numbers kills
+   the accumulating vertical text drift in parity (P3.1). Runs inside a headless scene so
+   LocalFontFamilyResolver supplies the platform resolver. */
+@OptIn(ExperimentalComposeUiApi::class)
+private fun printParagraphMetrics() {
+    val scene = ImageComposeScene(100, 100, density = Density(1f)) {
+        val resolver = androidx.compose.ui.platform.LocalFontFamilyResolver.current
+        val density = Density(1f)
+        fun paragraph(text: String, size: Int, lineHeight: Int?, m3Style: Boolean): androidx.compose.ui.text.Paragraph =
+            androidx.compose.ui.text.Paragraph(
+                text = text,
+                style = androidx.compose.ui.text.TextStyle(
+                    fontSize = size.sp,
+                    lineHeight = lineHeight?.sp ?: androidx.compose.ui.unit.TextUnit.Unspecified,
+                    fontFamily = notoSans,
+                    lineHeightStyle = if (m3Style) {
+                        androidx.compose.ui.text.style.LineHeightStyle(
+                            alignment = androidx.compose.ui.text.style.LineHeightStyle.Alignment.Center,
+                            trim = androidx.compose.ui.text.style.LineHeightStyle.Trim.None,
+                        )
+                    } else null,
+                ),
+                constraints = androidx.compose.ui.unit.Constraints(maxWidth = 10_000),
+                density = density,
+                fontFamilyResolver = resolver,
+            )
+        // What the demo's Text actually resolves to on this leg — is lineHeightStyle set?
+        println("metrics: m3 bodyMedium = ${Typography().bodyMedium.fontSize}/${Typography().bodyMedium.lineHeight} lineHeightStyle=${Typography().bodyMedium.lineHeightStyle}")
+        for (size in listOf(11, 12, 14, 16, 22, 24)) {
+            val lh = size + 6
+            val cell = paragraph("Hg", size, null, false)
+            val one = paragraph("Hg", size, lh, false)
+            val three = paragraph("Hg\nHg\nHg", size, lh, false)
+            val oneM3 = paragraph("Hg", size, lh, true)
+            val threeM3 = paragraph("Hg\nHg\nHg", size, lh, true)
+            println(
+                "metrics: size=$size lh=$lh cell=${cell.height} " +
+                    "one=${one.height} three=${three.height} " +
+                    "base1=${one.firstBaseline} base3=${three.lastBaseline} " +
+                    "oneM3=${oneM3.height} threeM3=${threeM3.height} base1M3=${oneM3.firstBaseline}"
+            )
+        }
+        // h-boundary cases: does upstream apply lineHeight at exactly 1em?
+        for ((s, l) in listOf(24 to 24, 24 to 25, 32 to 24, 16 to 16)) {
+            val b = paragraph("Hg", s, l, true)
+            println("metrics: boundary $s/$l m3=${b.height} base=${b.firstBaseline}")
+        }
+        // The band-smaller-than-cell case (Counter's fontSize=48 under body lineHeight).
+        val big = paragraph("42", 48, 24, false)
+        val bigM3 = paragraph("42", 48, 24, true)
+        println("metrics: big48/lh24 raw=${big.height} base=${big.firstBaseline} m3=${bigM3.height} baseM3=${bigM3.firstBaseline}")
+        println("metrics: DONE")
+    }
+    try {
+        scene.render()
+    } finally {
+        scene.close()
+    }
+}
+
+/* Same wrapper as MainNative's --screen path — plus NotoSans font-alignment (P0.3) so the
+   parity diff isn't dominated by the JVM's default typeface. */
 @Composable
 private fun ScreenHost(content: @Composable () -> Unit) {
-    MaterialTheme(colorScheme = darkColorScheme()) {
-        Box(
-            modifier = Modifier
-                .fillMaxSize()
-                .background(MaterialTheme.colorScheme.background)
-                .verticalScroll(rememberScrollState())
-                .padding(24.dp),
-        ) { content() }
+    val family = notoSans
+    MaterialTheme(
+        colorScheme = darkColorScheme(),
+        typography = if (family != null) notoTypography(family) else Typography(),
+    ) {
+        val base = LocalTextStyle.current
+        CompositionLocalProvider(
+            LocalTextStyle provides (if (family != null) base.copy(fontFamily = family) else base),
+        ) {
+            Box(
+                modifier = Modifier
+                    .fillMaxSize()
+                    .background(MaterialTheme.colorScheme.background)
+                    .verticalScroll(rememberScrollState())
+                    .padding(24.dp),
+            ) { content() }
+        }
     }
 }

demo/src/linuxMain/kotlin/SoakRss.linux.kt

@@ -0,0 +1,18 @@
+import kotlinx.cinterop.ExperimentalForeignApi
+import kotlinx.cinterop.allocArray
+import kotlinx.cinterop.memScoped
+import kotlinx.cinterop.toKString
+
+// Current resident set (MB) via `ps -o rss=` (KB). See currentResidentMb in MainNative.kt.
+@OptIn(ExperimentalForeignApi::class)
+internal actual fun currentResidentMb(): Long {
+    val vPid = platform.posix.getpid()
+    val vFp = platform.posix.popen("ps -o rss= -p $vPid", "r") ?: return -1
+    val vKb = memScoped {
+        val vBuf = allocArray<kotlinx.cinterop.ByteVar>(64)
+        val vLine = platform.posix.fgets(vBuf, 64, vFp)?.toKString()?.trim()
+        vLine?.toLongOrNull() ?: -1L
+    }
+    platform.posix.pclose(vFp)
+    return if (vKb < 0) -1 else vKb / 1024
+}

demo/src/mingwMain/kotlin/SoakRss.mingw.kt

@@ -0,0 +1,3 @@
+// Windows has no `ps`/popen; the memory soak (--soaktest) is a macOS/Linux gate
+// (see scripts/verify-mac.sh), so current RSS is not sampled here.
+internal actual fun currentResidentMb(): Long = -1L

demo/src/nativeMain/kotlin/MainNative.kt

@@ -25,6 +25,10 @@ import screens.ExtraWindows
 import utils.encodeBmpBgra32
 import utils.parseArgs
 import utils.writeFile
+import kotlinx.cinterop.ExperimentalForeignApi
+import kotlinx.cinterop.allocArray
+import kotlinx.cinterop.memScoped
+import kotlinx.cinterop.toKString
 
 // ==================
 // MARK: Entry point
@@ -95,6 +99,12 @@ fun main(args: Array<String>) {
         runParagraphTest()
         return
     }
+    // Prints Paragraph cell/line metrics for a size sweep — compare against the JVM
+    // leg's `--metrics` output to align the SDL text metrics with upstream (P3.1).
+    if (args.any { it == "--metricsprobe" }) {
+        runMetricsProbe()
+        return
+    }
     // Verifies the Dialog appearance animation (upstream Dialog.skiko.kt parity):
     // opens a real m3 AlertDialog via an injected click, dumps mid-animation and
     // settled screenshots — the mid shots must show the dialog fainter and lower.
@@ -117,6 +127,10 @@ fun main(args: Array<String>) {
         runNav3Test()
         return
     }
+    if (args.any { it == "--soaktest" }) {
+        runSoakTest()
+        return
+    }
 
     val vCli = parseArgs(args)
     val vTitle = buildString {
@@ -125,6 +139,15 @@ fun main(args: Array<String>) {
         append(" [").append(vCli.gpu).append("]")
     }
 
+    // Screenshot runs freeze infinite animations (rememberInfiniteTransition & co. cancel
+    // at their initial value) so every screen can reach quiescence, and step the frame
+    // clocks on VIRTUAL time (16.6ms/frame, like the JVM leg's render(nanos)) so animation
+    // races resolve identically every run — both must be set before the first window composes.
+    if (vCli.screenshot != null) {
+        com.compose.sdl.disableInfiniteAnimations = true
+        com.compose.sdl.useVirtualFrameTime = true
+    }
+
     // Multi-window app shell: the showcase window plus any extra windows opened
     // from WindowScreen's "Multi-window" section (state-driven, Compose Desktop
     // style — the count IS the windows' lifetime).
@@ -136,14 +159,23 @@ fun main(args: Array<String>) {
         height = vCli.height,
         gpu = vCli.gpu,
         onFrame = if (vCli.screenshot != null) {
+            // P0.5 render-to-quiescence: capture once the window reports no pending
+            // invalidations for a few consecutive frames (entrance animations settled,
+            // async loads applied), or at the --frames cap as a safety net. Replaces
+            // the fixed frame-6 capture, whose mid-animation timing was run-dependent.
+            var vQuietFrames = 0
             { bridge, frameIndex ->
-                if (frameIndex == vCli.frames) {
+                vQuietFrames = if (com.compose.sdl.windowHasInvalidations()) 0 else vQuietFrames + 1
+                if (vQuietFrames >= 3 || frameIndex >= vCli.maxFrames) {
+                    if (frameIndex >= vCli.maxFrames) {
+                        println("Screenshot: quiescence not reached by frame $frameIndex - capturing anyway")
+                    }
                     val vSnap = bridge.snapshotBgra()
                     if (vSnap != null) {
                         val (vW, vH, vBgra) = vSnap
                         val vBmp = encodeBmpBgra32(vW, vH, vBgra)
                         writeFile(vCli.screenshot, vBmp)
-                        println("Wrote screenshot: ${vCli.screenshot} (${vW}x${vH})")
+                        println("Wrote screenshot: ${vCli.screenshot} (${vW}x${vH}, settled at frame $frameIndex)")
                     } else println("Screenshot snapshot was null")
                     false  // quit
                 } else true
@@ -447,6 +479,96 @@ private fun runSearchEscTest() {
    Crashes here (e.g. enableSavedStateHandles' INITIALIZED/CREATED contract) never
    reproduce under --screen, which composes during the initial CREATED composition.
    PASS = a screenshot gets written and the app exits cleanly. */
+/* P2.2 soak — cycle through EVERY registered screen kCycles times in ONE process,
+   disposing each via a changing key() so composition + layer (skiko RenderNode / SDL
+   node) allocate-and-release is exercised repeatedly. After each full cycle, GC then
+   record peak RSS (getrusage ru_maxrss). Peak RSS is monotonic, so after cycle 1 it
+   already reflects visiting every screen once; if there is NO leak it plateaus, if
+   there IS one it keeps climbing each cycle. PASS iff last-cycle peak stays within a
+   ceiling of the first-cycle peak. Runs on both renderer legs. */
+@OptIn(kotlin.native.runtime.NativeRuntimeApi::class, ExperimentalForeignApi::class)
+private fun runSoakTest() {
+    // Disable never-settling animations so RSS reflects composition/layer lifetime,
+    // not live animation-state churn (same seed the screenshot path uses).
+    com.compose.sdl.disableInfiniteAnimations = true
+    com.compose.sdl.useVirtualFrameTime = true
+    val vAll = allCategories().flatMap { it.screens }
+    // CDN_SOAK_SCREEN=<name> repeats ONE screen 40x/cycle (bisect a specific screen);
+    // default cycles through every screen.
+    val vTarget = platform.posix.getenv("CDN_SOAK_SCREEN")?.toKString()
+    val vScreens = if (vTarget != null) { val vS = vAll.first { it.name.equals(vTarget, ignoreCase = true) }; List(40) { vS } }
+        else vAll
+    val vIndex = mutableStateOf(0)
+    // CDN_SOAK_STATIC=1: mount ONE screen once, never remount — measure RSS every 120 frames.
+    // Isolates a per-FRAME leak (RSS climbs with no remounts) from a per-MOUNT leak.
+    val vStatic = platform.posix.getenv("CDN_SOAK_STATIC")?.toKString() == "1"
+    val kFramesPerScreen = if (vStatic) 120 else 3
+    val kCycles = platform.posix.getenv("CDN_SOAK_CYCLES")?.toKString()?.toIntOrNull() ?: 3
+    val vRssPerCycleMb = mutableListOf<Long>()
+    var vShown = 0
+
+    nativeComposeWindow(
+        title = "soaktest",
+        width = 1000,
+        height = 700,
+        onFrame = { _, vFrame ->
+            if (vFrame > 0 && vFrame % kFramesPerScreen == 0) {
+                if (vStatic) {
+                    // No remount — just pump frames on the one mounted screen.
+                    kotlin.native.runtime.GC.collect()
+                    vRssPerCycleMb.add(currentResidentMb())
+                    println("soaktest[static]: measure ${vRssPerCycleMb.size}: currentRSS=${vRssPerCycleMb.last()}MB")
+                } else {
+                    vShown++
+                    vIndex.value = vShown % vScreens.size
+                    if (vShown % vScreens.size == 0) {
+                        kotlin.native.runtime.GC.collect()
+                        vRssPerCycleMb.add(currentResidentMb())
+                        println("soaktest: cycle ${vRssPerCycleMb.size}: currentRSS=${vRssPerCycleMb.last()}MB")
+                    }
+                }
+            }
+            if (vRssPerCycleMb.size >= kCycles) {
+                val vFirst = vRssPerCycleMb.first()
+                val vLast = vRssPerCycleMb.last()
+                val vGrowth = vLast - vFirst
+                val vCeiling = maxOf(48L, vFirst / 4)  // 25% or 48MB, whichever larger
+                println("soaktest: currentRSS/cycle(MB)=$vRssPerCycleMb (${vScreens.size} screens x $kCycles cycles)")
+                if (vGrowth <= vCeiling) {
+                    println("soaktest: PASS (current RSS grew ${vGrowth}MB over cycles 1->$kCycles, within ${vCeiling}MB ceiling)")
+                } else {
+                    println("soaktest: FAIL (current RSS grew ${vGrowth}MB > ${vCeiling}MB ceiling — possible leak)")
+                }
+                false
+            } else true
+        },
+    ) {
+        MaterialTheme(colorScheme = darkColorScheme()) {
+            val vScroll = rememberScrollState()
+            Box(
+                modifier = Modifier
+                    .fillMaxSize()
+                    .background(MaterialTheme.colorScheme.background)
+                    .verticalScroll(vScroll)
+                    .padding(24.dp),
+            ) {
+                // key(vShown) forces a FULL dispose+recompose each advance (even when the
+                // target screen repeats) — the allocate/release churn we soak. Reading
+                // vIndex.value (a State) is what triggers the recomposition each mount.
+                key(vShown) {
+                    vScreens[vIndex.value].content()
+                }
+            }
+        }
+    }
+}
+
+/* CURRENT resident set (MB): current RSS can DROP after GC, so it distinguishes a
+   true leak (ratchets up) from K/N allocator high-water, unlike getrusage's
+   monotonic peak. posix reads it from `ps`; mingw has no `ps`/popen and returns
+   -1 (the soak gate runs on macOS/Linux — see scripts/verify-mac.sh). */
+internal expect fun currentResidentMb(): Long
+
 private fun runNav3Test() {
     val vShow = mutableStateOf(false)
     nativeComposeWindow(
@@ -652,6 +774,65 @@ private fun runParagraphTest() {
     }
 }
 
+/* Prints paragraph metrics (single-line cell, lineHeight-styled single + triple line,
+   first baseline) for a font-size sweep at density 1 — the native half of the
+   metrics-alignment probe. Mirror of MainJvm's `--metrics`; both must print the same
+   numbers for the parity text drift to vanish. */
+private fun runMetricsProbe() {
+    fun paragraph(inText: String, inSize: Int, inLineHeight: Int?, inM3Style: Boolean): androidx.compose.ui.text.Paragraph =
+        androidx.compose.ui.text.Paragraph(
+            text = inText,
+            style = androidx.compose.ui.text.TextStyle(
+                fontSize = inSize.sp,
+                lineHeight = inLineHeight?.sp ?: androidx.compose.ui.unit.TextUnit.Unspecified,
+                lineHeightStyle = if (inM3Style) {
+                    androidx.compose.ui.text.style.LineHeightStyle(
+                        alignment = androidx.compose.ui.text.style.LineHeightStyle.Alignment.Center,
+                        trim = androidx.compose.ui.text.style.LineHeightStyle.Trim.None,
+                    )
+                } else null,
+            ),
+            constraints = androidx.compose.ui.unit.Constraints(maxWidth = 10_000),
+            density = androidx.compose.ui.unit.Density(1f),
+            fontFamilyResolver = androidx.compose.ui.text.font.createFontFamilyResolver(),
+            overflow = androidx.compose.ui.text.style.TextOverflow.Clip,
+        )
+    nativeComposeWindow(
+        title = "metricsprobe",
+        width = 300,
+        height = 200,
+        onFrame = { _, frameIndex ->
+            if (frameIndex == 10) {
+                for (vSize in listOf(11, 12, 14, 16, 22, 24)) {
+                    val vLh = vSize + 6
+                    val vCell = paragraph("Hg", vSize, null, false)
+                    val vOne = paragraph("Hg", vSize, vLh, false)
+                    val vThree = paragraph("Hg\nHg\nHg", vSize, vLh, false)
+                    val vOneM3 = paragraph("Hg", vSize, vLh, true)
+                    val vThreeM3 = paragraph("Hg\nHg\nHg", vSize, vLh, true)
+                    println(
+                        "metrics: size=$vSize lh=$vLh cell=${vCell.height} " +
+                            "one=${vOne.height} three=${vThree.height} " +
+                            "base1=${vOne.firstBaseline} base3=${vThree.lastBaseline} " +
+                            "oneM3=${vOneM3.height} threeM3=${vThreeM3.height} base1M3=${vOneM3.firstBaseline}"
+                    )
+                }
+                for ((vS, vL) in listOf(24 to 24, 24 to 25, 32 to 24, 16 to 16)) {
+                    val vB = paragraph("Hg", vS, vL, true)
+                    println("metrics: boundary $vS/$vL m3=${vB.height} base=${vB.firstBaseline}")
+                }
+                val vBig = paragraph("42", 48, 24, false)
+                val vBigM3 = paragraph("42", 48, 24, true)
+                println("metrics: big48/lh24 raw=${vBig.height} base=${vBig.firstBaseline} m3=${vBigM3.height} baseM3=${vBigM3.firstBaseline}")
+                println("metricsprobe: DONE")
+                false
+            } else true
+        },
+    ) {
+        Box(modifier = Modifier.fillMaxSize()) {}
+    }
+}
+
 // ==================
 // MARK: clicktest
 // ==================

demo/src/nativeMain/kotlin/utils/CliArgs.kt

@@ -13,9 +13,10 @@ import com.compose.sdl.GpuMode
          sdl3.opengl | sdl3.metal | sdl3.vulkan |
          sdl3.d3d11 | sdl3.d3d12                 (default: auto)
    --screen=Buttons | TextField | ...            (default: full app w/ sidebar)
-   --screenshot=path.bmp                         capture after frames and quit
+   --screenshot=path.bmp                         capture at quiescence and quit
    --width=W  --height=H                         (default 1000 / 700)
-   --frames=N                                    screenshot delay in frames
+   --frames=N                                    quiescence cap: capture at frame N even if
+                                                 the screen never settles (default 300)
 
    Names match the Screen registry entries (case-insensitive). */
 internal data class CliArgs(
@@ -24,7 +25,7 @@ internal data class CliArgs(
     val screenshot: String? = null,
     val width: Int = 1000,
     val height: Int = 700,
-    val frames: Int = 6,
+    val maxFrames: Int = 300,
 )
 
 /* Translates the --gpu= string to the right GpuMode sealed instance.
@@ -62,7 +63,7 @@ internal fun parseArgs(argv: Array<String>): CliArgs {
             "screenshot" -> vArgs.copy(screenshot = value)
             "width"      -> vArgs.copy(width = value.toIntOrNull() ?: vArgs.width)
             "height"     -> vArgs.copy(height = value.toIntOrNull() ?: vArgs.height)
-            "frames"     -> vArgs.copy(frames = value.toIntOrNull() ?: vArgs.frames)
+            "frames"     -> vArgs.copy(maxFrames = value.toIntOrNull() ?: vArgs.maxFrames)
             else -> vArgs
         }
     }

gradle-plugin/compose-desktop-native-bridge/README.md

@@ -45,20 +45,35 @@ dependencyResolutionManagement {
 ```
 
 ```kotlin
-// module build.gradle.kts — official coords, everywhere
+// module build.gradle.kts — official coords, everywhere.
+// Applying the plugin HERE exposes the `composeDesktopNative` extension, which
+// reports the exact Compose versions the port tracks, so you never hand-match
+// them against compose.properties.
+plugins {
+    kotlin("multiplatform")
+    id("org.jetbrains.compose")
+    id("com.bitsycore.compose-desktop-native.bridge")
+}
+
 kotlin {
     macosArm64(); linuxX64(); mingwX64()   // + jvm()/android()/ios if you like
     sourceSets {
         commonMain.dependencies {
-            implementation("org.jetbrains.compose.runtime:runtime:1.11.1")
-            implementation("org.jetbrains.compose.ui:ui:<cmp-version>")
-            implementation("org.jetbrains.compose.foundation:foundation:<cmp-version>")
-            implementation("org.jetbrains.compose.material3:material3:<cmp-m3-version>")
+            implementation("org.jetbrains.compose.runtime:runtime:${composeDesktopNative.composeRuntime}")
+            implementation("org.jetbrains.compose.ui:ui:${composeDesktopNative.compose}")
+            implementation("org.jetbrains.compose.foundation:foundation:${composeDesktopNative.compose}")
+            implementation("org.jetbrains.compose.material3:material3:${composeDesktopNative.composeMaterial3}")
         }
     }
 }
 ```
 
+`composeDesktopNative` exposes four read-only values: `compose` (ui /
+foundation / animation / material), `composeMaterial3` (versioned separately
+upstream), `composeRuntime`, and `version` (the port klib version being
+substituted). You can still write literal versions if you prefer; the extension
+just removes the drift.
+
 ### Settings-wide or per-module
 
 The plugin applies at either level:
@@ -80,6 +95,16 @@ version (so module-level applications can omit it); the top-level
 Rule of thumb: single app module → apply in the module; multi-module builds →
 apply once in settings.
 
+When applied from settings, the type-safe `composeDesktopNative` accessor is not
+generated in the module scripts. The same values are still available through
+project extra properties:
+
+```kotlin
+val compose = project.extra["composeDesktopNative.compose"] as String
+val material3 = project.extra["composeDesktopNative.composeMaterial3"] as String
+val runtime = project.extra["composeDesktopNative.composeRuntime"] as String
+```
+
 ## compose.desktop.native — the application block for native
 
 The native counterpart of `compose.desktop { application { mainClass } }`:
@@ -122,10 +147,12 @@ overrides follow the default hierarchy (a `mingwX64Main` resource beats a
 - The substituted klib version defaults to the plugin's own version (both ship
   from the same tag). Override with `composeDesktopNative.version=<x>` in
   `gradle.properties` when mixing releases.
-- Match `<cmp-version>` to the CMP release the port's vendored sources track
-  (see `scripts/compose-fork/compose.properties` at the release tag) —
-  substitution replaces whatever version you request on native, but your
-  jvm/android targets resolve the official artifacts at the version you write.
+- Use `composeDesktopNative.compose` / `.composeMaterial3` / `.composeRuntime`
+  (above) for the official coords rather than hardcoding a version. Substitution
+  replaces the requested version on native, but your jvm/android targets resolve
+  the official artifacts at the version you write, so matching what the port
+  tracks keeps every target on the same API. The values come straight from the
+  release the plugin shipped with; no need to read `compose.properties` by hand.
 - Requires Gradle 8.8+ when applied in settings (`gradle.lifecycle.beforeProject`).
 - App windowing/main-loop (`com.bitsycore.compose.sdl:window`) and the icon
   font module (`material-symbols`) are the port's own APIs — depend on them

gradle-plugin/compose-desktop-native-bridge/build.gradle.kts

@@ -31,16 +31,30 @@ gradlePlugin {
 }
 
 // The plugin defaults the substitution version to ITS OWN version (plugin and
-// klibs ship from the same tag), read at runtime from this generated resource.
+// klibs ship from the same tag) and also ADVERTISES the official Compose
+// Multiplatform versions the port tracks, so consumers declare the matching
+// coords without reading compose.properties by hand. Both are read at runtime
+// from this generated resource, sourced from the version catalog (single truth).
 val vVersionDir = layout.buildDirectory.dir("generated/bridge-version")
 val vGenerateVersion = tasks.register("generateBridgeVersionResource") {
     val vVersion = project.version.toString()
+    val vCompose = libs.versions.compose.get()
+    val vComposeMaterial3 = libs.versions.composeMaterial3.get()
+    val vComposeRuntime = libs.versions.composeRuntime.get()
     val vOut = vVersionDir.get().file("com/bitsycore/compose/sdl/gradle/bridge-version.properties").asFile
     inputs.property("version", vVersion)
+    inputs.property("compose", vCompose)
+    inputs.property("composeMaterial3", vComposeMaterial3)
+    inputs.property("composeRuntime", vComposeRuntime)
     outputs.dir(vVersionDir)
     doLast {
         vOut.parentFile.mkdirs()
-        vOut.writeText("version=$vVersion\n")
+        vOut.writeText(
+            "version=$vVersion\n" +
+                "compose=$vCompose\n" +
+                "composeMaterial3=$vComposeMaterial3\n" +
+                "composeRuntime=$vComposeRuntime\n"
+        )
     }
 }
 sourceSets["main"].resources.srcDir(vVersionDir)

gradle-plugin/compose-desktop-native-bridge/src/main/kotlin/com/bitsycore/compose/sdl/gradle/ComposeDesktopNativeBridgePlugin.kt

@@ -45,6 +45,45 @@ private const val portGroup = "com.bitsycore.compose.sdl"
 /** Gradle property overriding the substitution version (default: the plugin's own). */
 private const val versionProperty = "composeDesktopNative.version"
 
+// ==================
+// MARK: composeDesktopNative { } — version info exposed to the consumer
+// ==================
+
+/**
+ * Read-only info the bridge exposes to the consuming build as the project
+ * extension `composeDesktopNative`. Use it to declare the official Compose
+ * Multiplatform coordinates that match the port's vendored sources, so
+ * jvm/android targets stay aligned with what the native klibs were built from
+ * (no more reading compose.properties at the release tag by hand):
+ *
+ * ```kotlin
+ * commonMain.dependencies {
+ *     implementation("org.jetbrains.compose.runtime:runtime:${composeDesktopNative.composeRuntime}")
+ *     implementation("org.jetbrains.compose.ui:ui:${composeDesktopNative.compose}")
+ *     implementation("org.jetbrains.compose.foundation:foundation:${composeDesktopNative.compose}")
+ *     implementation("org.jetbrains.compose.material3:material3:${composeDesktopNative.composeMaterial3}")
+ * }
+ * ```
+ *
+ * The same values are mirrored into `project.extra` (keys `composeDesktopNative.compose`,
+ * `.composeMaterial3`, `.composeRuntime`, `.version`) for builds that apply the
+ * plugin from settings, where the type-safe accessor is not generated.
+ *
+ * The substituted PORT klib version is overridden with the
+ * `composeDesktopNative.version` Gradle property (see [version]); this extension
+ * only reports the effective value.
+ */
+open class ComposeDesktopNativeBridgeExtension(
+	/** The port klib version substituted on native targets (after the `composeDesktopNative.version` override). */
+	val version: String,
+	/** Official Compose version for ui / foundation / animation / material. */
+	val compose: String,
+	/** Official material3 version (versioned separately upstream). */
+	val composeMaterial3: String,
+	/** Official Compose runtime version (never substituted; serves every target). */
+	val composeRuntime: String,
+)
+
 // ==================
 // MARK: Plugin
 // ==================
@@ -58,7 +97,9 @@ private const val versionProperty = "composeDesktopNative.version"
  *
  * Apply in settings.gradle.kts (covers every project) or in a single module's
  * build.gradle.kts. The substituted version defaults to the plugin's own
- * version — override with `composeSdl.version` in gradle.properties.
+ * version — override with `composeDesktopNative.version` in gradle.properties.
+ * The official Compose versions the port tracks are exposed via the
+ * `composeDesktopNative` extension (see [ComposeDesktopNativeBridgeExtension]).
  */
 class ComposeDesktopNativeBridgePlugin : Plugin<Any> {
 
@@ -81,7 +122,30 @@ class ComposeDesktopNativeBridgePlugin : Plugin<Any> {
 private fun installBridge(project: Project) {
 	installResourcePackaging(project)
 	installNativeApplicationDsl(project)
-	val version = project.providers.gradleProperty(versionProperty).orNull ?: pluginVersion
+
+	// The effective port version: the override property, else the plugin's own.
+	val version = project.providers.gradleProperty(versionProperty).orNull ?: bridgeProperty("version")
+
+	// Advertise the Compose versions the port tracks so consumers align their
+	// official coords without guessing. Extension for the common per-module apply
+	// (type-safe accessor); extra properties for the settings apply (no accessor).
+	if (project.extensions.findByName("composeDesktopNative") == null) {
+		project.extensions.create(
+			"composeDesktopNative",
+			ComposeDesktopNativeBridgeExtension::class.java,
+			version,
+			bridgeProperty("compose"),
+			bridgeProperty("composeMaterial3"),
+			bridgeProperty("composeRuntime"),
+		)
+	}
+	project.extensions.extraProperties.let { extra ->
+		extra["composeDesktopNative.version"] = version
+		extra["composeDesktopNative.compose"] = bridgeProperty("compose")
+		extra["composeDesktopNative.composeMaterial3"] = bridgeProperty("composeMaterial3")
+		extra["composeDesktopNative.composeRuntime"] = bridgeProperty("composeRuntime")
+	}
+
 	project.configurations.configureEach { configuration ->
 		if (nativeTargetTokens.any { configuration.name.contains(it, ignoreCase = true) }) {
 			configuration.resolutionStrategy.dependencySubstitution { substitutions ->
@@ -98,12 +162,17 @@ private fun installBridge(project: Project) {
 	}
 }
 
-/** The plugin's own version, stamped into a resource at build time. */
-private val pluginVersion: String by lazy {
+/* The plugin's own version + the Compose versions it tracks, stamped into a
+   resource at build time (from the version catalog). `version` is the plugin's
+   own release; the rest are the official CMP versions the port's vendored
+   sources build against. */
+private val bridgeProperties: Properties by lazy {
 	val stream = ComposeDesktopNativeBridgePlugin::class.java
 		.getResourceAsStream("bridge-version.properties")
 		?: throw GradleException("com.bitsycore.compose-desktop-native.bridge: missing bridge-version.properties resource")
-	val properties = Properties().apply { stream.use { load(it) } }
-	properties.getProperty("version")
-		?: throw GradleException("com.bitsycore.compose-desktop-native.bridge: bridge-version.properties has no 'version'")
+	Properties().apply { stream.use { load(it) } }
 }
+
+private fun bridgeProperty(key: String): String =
+	bridgeProperties.getProperty(key)
+		?: throw GradleException("com.bitsycore.compose-desktop-native.bridge: bridge-version.properties has no '$key'")

gradle/libs.versions.toml

@@ -1,6 +1,16 @@
 [versions]
 kotlin = "2.4.0"
-compose = "1.12.0-beta01"
+# Official Compose Multiplatform versions the port's vendored sources track and
+# the JVM parity leg forces. SINGLE SOURCE: consumed by the bridge plugin
+# (stamped into bridge-version.properties and exposed to consumers) and by
+# demo / apidemo / material-symbols. Keep in lockstep with the vendored ref in
+# scripts/compose-fork/compose.properties on each bump.
+#   compose          = ui / foundation / animation / material
+#   composeMaterial3 = material3 (versioned separately upstream)
+#   composeRuntime   = the official runtime klibs (never substituted)
+compose = "1.12.0-beta02"
+composeMaterial3 = "1.12.0-alpha03"
+composeRuntime = "1.11.1"
 kotlinxCoroutines = "1.11.0"
 kotlinxDateTime = "0.8.0"
 kotlinxSerialization = "1.11.0"

scripts/compose-fork/check-vendor-clean.py

@@ -0,0 +1,127 @@
+#!/usr/bin/env python3
+# Vendor-clean check (P0.7, RENDERER.md) - fails if src/vendor/ has drifted from
+# what the pinned upstream refs produce.
+#
+# src/vendor/ is REGENERATED OUTPUT (gitignored): nothing hand-made may live there. A
+# hand-edit that leaks in "works on my machine" but silently diverges from every clean
+# checkout, and is overwritten by the next sync. This check makes that loud:
+#
+#   1. hash every file under each module's src/vendor/ (and snapshot each compose-fork.txt)
+#   2. run sync.py (regenerates the trees byte-for-byte from the pinned clones,
+#      deleting stale files and re-annotating manifests)
+#   3. re-hash and diff: ANY change/add/remove = the local tree did not match the pin
+#
+# On failure the tree has already been RESTORED to the pinned state (that is sync.py's
+# normal behaviour) - the report tells you what drifted. If the edit was intentional,
+# manual-vendor it instead (CLAUDE.md vendoring rule 3: move the file out of src/vendor/,
+# comment its manifest line out, re-sync). Manifest churn means the annotations were
+# stale - commit the refreshed manifest.
+#
+# Usage (from anywhere; ASCII-only output for cp1252 consoles):
+#   python scripts/compose-fork/check-vendor-clean.py
+# Exit: 0 clean · 1 drift found (tree now restored) · 2 sync itself failed
+
+import hashlib
+import os
+import subprocess
+import sys
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+REPO_ROOT = os.path.abspath(os.path.join(HERE, '..', '..'))
+PRUNE_DIRS = {'build', '.gradle', '.git', 'node_modules', 'scripts'}
+
+
+# ============
+#  Every module dir carrying a compose-fork.txt (same discovery rules as sync.py).
+def module_dirs():
+	found = []
+	for dirpath, dirs, files in os.walk(REPO_ROOT):
+		dirs[:] = [d for d in dirs if d not in PRUNE_DIRS]
+		if 'compose-fork.txt' in files:
+			found.append(dirpath)
+	return sorted(found)
+
+
+# ============
+#  {repo-relative-path: sha1} over one directory tree (empty dict if absent).
+def hash_tree(root):
+	out = {}
+	if not os.path.isdir(root):
+		return out
+	for dr, _, fs in os.walk(root):
+		for fn in fs:
+			p = os.path.join(dr, fn)
+			with open(p, 'rb') as fh:
+				digest = hashlib.sha1(fh.read()).hexdigest()
+			out[os.path.relpath(p, REPO_ROOT).replace(os.sep, '/')] = digest
+	return out
+
+
+def read_text(path):
+	with open(path, 'rb') as fh:
+		return fh.read()
+
+
+def main():
+	modules = module_dirs()
+	if not modules:
+		sys.stderr.write('check-vendor-clean: no compose-fork.txt manifests found\n')
+		return 2
+
+	# ---- 1. pre-sync snapshot: vendor hashes + manifest bytes
+	before = {}
+	manifests_before = {}
+	for mod in modules:
+		before.update(hash_tree(os.path.join(mod, 'src', 'vendor')))
+		mf = os.path.join(mod, 'compose-fork.txt')
+		manifests_before[mf] = read_text(mf)
+	print('check-vendor-clean: %d vendored files across %d modules - running sync.py'
+		% (len(before), len(modules)))
+
+	# ---- 2. regenerate from the pinned refs
+	rc = subprocess.run([sys.executable, os.path.join(HERE, 'sync.py')], cwd=REPO_ROOT).returncode
+	if rc != 0:
+		sys.stderr.write('check-vendor-clean: sync.py failed (rc=%d) - cannot judge cleanliness\n' % rc)
+		return 2
+
+	# ---- 3. post-sync diff
+	after = {}
+	for mod in modules:
+		after.update(hash_tree(os.path.join(mod, 'src', 'vendor')))
+	changed = sorted(p for p in before.keys() & after.keys() if before[p] != after[p])
+	removed = sorted(before.keys() - after.keys())
+	added = sorted(after.keys() - before.keys())
+	stale_manifests = sorted(
+		os.path.relpath(mf, REPO_ROOT).replace(os.sep, '/')
+		for mf, text in manifests_before.items() if read_text(mf) != text)
+
+	ok = True
+	if changed or removed or added:
+		ok = False
+		print('\ncheck-vendor-clean: FAIL - src/vendor/ did not match the pinned refs '
+			'(now restored by the sync):')
+		for p in changed:
+			print('  changed : %s' % p)
+		for p in removed:
+			print('  stale   : %s (removed - no manifest entry produces it)' % p)
+		for p in added:
+			print('  missing : %s (recreated - was absent locally)' % p)
+		print('src/vendor/ is regenerated output - never hand-edit it. Intentional edits '
+			'must be MANUAL-VENDORED (move out of src/vendor/, comment the manifest line, '
+			're-sync); see CLAUDE.md vendoring rule 3.')
+	if stale_manifests:
+		ok = False
+		print('\ncheck-vendor-clean: FAIL - manifest annotations were stale (sync refreshed '
+			'them; review + commit):')
+		for p in stale_manifests:
+			print('  manifest: %s' % p)
+
+	if ok:
+		print('check-vendor-clean: PASS - src/vendor/ matches the pinned refs '
+			'(%d files) and all manifests are stable' % len(after))
+		return 0
+	return 1
+
+
+if __name__ == '__main__':
+	sys.exit(main())

scripts/compose-fork/check-vendor-drift.py

@@ -0,0 +1,136 @@
+#!/usr/bin/env python3
+"""
+Vendor-drift tripwire (RENDERER.md P0.6 / §8).
+
+Manually-vendored files (copy-edited from upstream, NON-IDEMPOTENT) carry a
+machine-readable provenance line near their header:
+
+    // VENDOR-BASE: <upstream-repo-relative-path> @ <commit-or-tag>
+    // VENDOR-BASE(<VARNAME>): <path> @ <ref>     for a non-core repo, naming the
+                                                  compose.properties pin it tracks
+                                                  (e.g. COMPOSE_REF for the umbrella repo)
+
+recording the exact upstream ref the file was last reconciled against. This script
+compares each to the CURRENT pin for its repo (COMPOSE_CORE_REF by default) from
+scripts/compose-fork/compose.properties. If they differ, the manual vendor MAY be
+stale — upstream could have changed that file since it was reconciled — and must be
+re-checked by hand. Exits non-zero if any file is stale, so it can gate a ref bump.
+
+Deeper (optional) check: if the repo's local clone is found (../cmp-ref[-core] for the
+core repo, ../cmp-ref-compose-multiplatform for COMPOSE_REF), it runs
+`git diff <base>..<pin> -- <path>` and reports whether the upstream file ACTUALLY changed
+between the recorded base and the current pin — turning "might be stale" into
+"did / didn't change".
+
+Run at each pin bump (see RENDERER.md §9 ref-bump runbook).
+No third-party deps; Windows / macOS / Linux.
+"""
+import re, sys, subprocess
+from pathlib import Path
+
+REPO = Path(__file__).resolve().parents[2]
+PROPS = REPO / "scripts" / "compose-fork" / "compose.properties"
+MARKER = re.compile(r"VENDOR-BASE(?:\(([A-Z_][A-Z0-9_]*)\))?:\s*(\S+)\s*@\s*(\S+)")
+
+# Pin variable -> candidate clone dir names (sibling of the repo checkout).
+CLONES = {
+    "COMPOSE_CORE_REF": ("cmp-ref", "cmp-ref-core"),
+    "COMPOSE_REF": ("cmp-ref-compose-multiplatform",),
+}
+
+
+def read_pins() -> dict:
+    pins = {}
+    for line in PROPS.read_text(encoding="utf-8").splitlines():
+        s = line.strip()
+        if s and not s.startswith("#") and "=" in s:
+            name, val = s.split("=", 1)
+            pins[name.strip()] = val.strip()
+    if "COMPOSE_CORE_REF" not in pins:
+        raise SystemExit("check-vendor-drift: COMPOSE_CORE_REF not found in compose.properties")
+    return pins
+
+
+def find_clone(var: str):
+    for name in CLONES.get(var, ()):
+        p = REPO.parent / name
+        if (p / ".git").exists():
+            return p
+    return None
+
+
+def upstream_changed(clone: Path, path: str, base: str, pin: str):
+    """True if <path> differs between base..pin in the clone; None if it couldn't run
+    (including the path not existing at the pin — a rename/move needs human eyes)."""
+    try:
+        present = subprocess.run(
+            ["git", "-C", str(clone), "ls-tree", "--name-only", pin, "--", path],
+            capture_output=True, text=True,
+        )
+        if present.returncode != 0 or not present.stdout.strip():
+            return None  # ref missing locally or path gone at the pin
+        r = subprocess.run(
+            ["git", "-C", str(clone), "diff", "--quiet", f"{base}..{pin}", "--", path],
+            capture_output=True,
+        )
+        return r.returncode != 0  # `git diff --quiet` exits 1 when there ARE differences
+    except Exception:
+        return None
+
+
+def main() -> int:
+    pins = read_pins()
+
+    entries = []
+    for f in REPO.rglob("*.kt"):
+        if "/src/vendor/" in f.as_posix():
+            continue  # gitignored verbatim re-sync tree — not manual vendors
+        try:
+            text = f.read_text(encoding="utf-8", errors="ignore")
+        except Exception:
+            continue
+        for m in MARKER.finditer(text):
+            var = m.group(1) or "COMPOSE_CORE_REF"
+            entries.append((f, var, m.group(2), m.group(3)))
+
+    if not entries:
+        print("check-vendor-drift: no VENDOR-BASE annotations found.")
+        return 0
+
+    used_vars = sorted({var for _, var, _, _ in entries})
+    for var in used_vars:
+        print(f"check-vendor-drift: pin {var} = {pins.get(var, '(NOT IN compose.properties!)')}"
+              f"  clone = {find_clone(var) or '(none — ref-compare only)'}")
+    print()
+
+    stale = []
+    for f, var, path, base in sorted(entries, key=lambda e: e[0].as_posix()):
+        rel = f.relative_to(REPO).as_posix()
+        pin = pins.get(var)
+        if pin is None:
+            stale.append(rel)
+            print(f"  STALE {rel}\n        tracks unknown pin variable {var!r}")
+            continue
+        if base == pin:
+            print(f"  OK    {rel}  (base == pin {var})")
+            continue
+        note = ""
+        clone = find_clone(var)
+        if clone:
+            ch = upstream_changed(clone, path, base, pin)
+            note = ("  <-- upstream CHANGED base..pin; RECONCILE" if ch is True
+                    else "  (upstream unchanged base..pin; safe to bump the VENDOR-BASE ref)"
+                    if ch is False else "  (clone diff unavailable)")
+        stale.append(rel)
+        print(f"  STALE {rel}\n        base @ {base}\n        pin  @ {pin} ({var}){note}")
+
+    if stale:
+        print(f"\ncheck-vendor-drift: {len(stale)} stale manual-vendor(s). Reconcile each against "
+              f"its pinned upstream, then update its VENDOR-BASE ref.")
+        return 1
+    print("\ncheck-vendor-drift: all manual vendors match their pins. OK.")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())

scripts/compose-fork/compose.properties

@@ -2,8 +2,15 @@
 # module's compose-fork.txt as SET_REPO=<url>@<VARNAME>. Bump a ref here and
 # re-run scripts/compose-fork/sync.sh to re-sync everything to it.
 
-# JetBrains/compose-multiplatform-core  (tag v1.12.0-beta01+dev4324)
-COMPOSE_CORE_REF=1be9d64ad12db0c79f44aedf9d9388e644c60871
+# JetBrains/compose-multiplatform-core -- pinned to the durable TAG (fetchable by name
+# from any fresh clone, unlike a bare unreferenced SHA which upstream could GC).
+# 2026-07-18 O.2 bump: beta02 -> v1.12.0-beta03+dev4483. No CLEAN beta03/rc/stable tag
+# exists on either repo yet, and beta03 is NOT on Maven Central, so this is the latest
+# DURABLE (fetchable-by-name tag) ref. VENDORED (native) side only: the JVM parity leg's
+# Maven forcing (compose 1.12.0-beta02 / m3 1.12.0-alpha03, latest PUBLISHED) stays put --
+# a documented native(beta03+dev) vs JVM(beta02) skew until beta03 hits Maven Central, at
+# which point bump the vComposeJvmVersion forcing in demo/apidemo/material-symbols to match.
+COMPOSE_CORE_REF=v1.12.0-beta03+dev4483
 
 # JetBrains/compose-multiplatform  (umbrella repo -- :components-resources runtime)
-COMPOSE_REF=v1.12.0-beta01
+COMPOSE_REF=v1.12.0-beta03+dev4483

scripts/compose-fork/sync.py

@@ -359,8 +359,14 @@ def ensure_clone(url, ref, sparse_dirs):
 		git(clone_dir, ['sparse-checkout', 'set', *sparse_dirs], quiet=True)
 	if git(clone_dir, ['checkout', '-q', ref], quiet=True, check=False).returncode != 0:
 		print('ref %s not present locally -- fetching' % ref)
-		git(clone_dir, ['fetch', 'origin', ref])
-		git(clone_dir, ['checkout', '-q', ref])
+		# Try as a TAG first, mapping it to a local tag ref -- a plain `fetch origin <tag>`
+		# only lands in FETCH_HEAD, so the checkout below would fail and every future sync
+		# would need the network again. Branches / bare SHAs fall back to the plain fetch.
+		if git(clone_dir, ['fetch', 'origin', 'refs/tags/%s:refs/tags/%s' % (ref, ref)],
+				quiet=True, check=False).returncode != 0:
+			git(clone_dir, ['fetch', 'origin', ref])
+		if git(clone_dir, ['checkout', '-q', ref], quiet=True, check=False).returncode != 0:
+			git(clone_dir, ['checkout', '-q', 'FETCH_HEAD'])
 	desc = subprocess.run(['git', '-C', clone_dir, 'describe', '--tags', '--always'],
 		capture_output=True, text=True).stdout.strip()
 	print('upstream %s @ %s' % (url.rstrip('/').split('/')[-1], desc))

scripts/parity/baselines.json

@@ -0,0 +1,179 @@
+{
+  "macosArm64/sdl3": {
+    "Animation": 3.11,
+    "AnnotatedString": 7.46,
+    "AppBars": 1.99,
+    "BasicText": 4.62,
+    "BasicTextField": 4.99,
+    "Brushes": 2.18,
+    "Buttons": 1.92,
+    "ButtonsExtra": 2.24,
+    "Canvas": 5.03,
+    "Cards": 2.28,
+    "Carousel": 2.06,
+    "Chips": 1.62,
+    "Clipboard": 2.94,
+    "Colors": 0.68,
+    "Counter": 0.65,
+    "CustomLayout": 19.13,
+    "Dialogs": 2.54,
+    "DragAndDrop": 1.85,
+    "Drawers": 1.3,
+    "Fab": 1.94,
+    "FabExtra": 1.35,
+    "FlowLayout": 2.46,
+    "FocusRequester": 2.85,
+    "Gestures": 2.68,
+    "GraphicsLayer": 4.7,
+    "GridsExtra": 1.29,
+    "Icons": 1.29,
+    "Images": 16.81,
+    "Interaction": 1.41,
+    "InteractionSource": 2.96,
+    "Layout": 2.12,
+    "LazyColumn": 2.7,
+    "LazyExtra": 2.91,
+    "LazyGrid": 1.67,
+    "Lists": 2.45,
+    "M3Misc": 1.65,
+    "MaterialSymbols": 2.99,
+    "ModShortcuts": 2.27,
+    "Modifiers": 2.28,
+    "NavRails": 1.38,
+    "Navigation": 1.79,
+    "Navigation3": 2.71,
+    "Pager": 0.98,
+    "Path": 6.22,
+    "Pickers": 19.47,
+    "PointerInput": 2.68,
+    "Recomposition": 1.51,
+    "Remember": 1.74,
+    "Scroll": 2.82,
+    "Search": 4.5,
+    "Shadows": 1.49,
+    "Shapes": 1.34,
+    "Sheets": 1.35,
+    "Tabs": 1.88,
+    "Text": 3.37,
+    "TextField": 1.95,
+    "Widgets": 2.21
+  },
+  "macosArm64/skia": {
+    "Animation": 3.11,
+    "AnnotatedString": 7.46,
+    "AppBars": 1.99,
+    "BasicText": 4.62,
+    "BasicTextField": 4.99,
+    "Brushes": 2.18,
+    "Buttons": 1.92,
+    "ButtonsExtra": 2.24,
+    "Canvas": 5.03,
+    "Cards": 2.28,
+    "Carousel": 2.06,
+    "Chips": 1.62,
+    "Clipboard": 2.94,
+    "Colors": 0.68,
+    "Counter": 0.65,
+    "CustomLayout": 19.13,
+    "Dialogs": 2.54,
+    "DragAndDrop": 1.85,
+    "Drawers": 1.3,
+    "Fab": 1.94,
+    "FabExtra": 1.35,
+    "FlowLayout": 2.46,
+    "FocusRequester": 2.85,
+    "Gestures": 2.68,
+    "GraphicsLayer": 4.65,
+    "GridsExtra": 1.29,
+    "Icons": 1.29,
+    "Images": 16.81,
+    "Interaction": 1.41,
+    "InteractionSource": 2.96,
+    "Layout": 2.12,
+    "LazyColumn": 2.7,
+    "LazyExtra": 2.91,
+    "LazyGrid": 1.67,
+    "Lists": 2.45,
+    "M3Misc": 1.65,
+    "MaterialSymbols": 2.99,
+    "ModShortcuts": 2.27,
+    "Modifiers": 2.28,
+    "NavRails": 1.38,
+    "Navigation": 1.79,
+    "Navigation3": 2.71,
+    "Pager": 0.98,
+    "Path": 6.22,
+    "Pickers": 19.47,
+    "PointerInput": 2.68,
+    "Recomposition": 1.51,
+    "Remember": 1.74,
+    "Scroll": 2.82,
+    "Search": 4.5,
+    "Shadows": 1.49,
+    "Shapes": 1.34,
+    "Sheets": 1.35,
+    "Tabs": 1.88,
+    "Text": 3.37,
+    "TextField": 1.95,
+    "Widgets": 2.21
+  },
+  "mingwX64/sdl3": {
+    "Animation": 3.0,
+    "AnnotatedString": 8.13,
+    "AppBars": 1.96,
+    "BasicText": 2.81,
+    "BasicTextField": 1.82,
+    "Brushes": 2.21,
+    "Buttons": 1.9,
+    "ButtonsExtra": 2.19,
+    "Canvas": 4.3,
+    "Cards": 2.29,
+    "Carousel": 1.9,
+    "Chips": 1.59,
+    "Clipboard": 3.03,
+    "Colors": 0.65,
+    "Counter": 0.58,
+    "CustomLayout": 4.1,
+    "Dialogs": 2.64,
+    "DragAndDrop": 1.84,
+    "Drawers": 1.38,
+    "Fab": 1.86,
+    "FabExtra": 1.38,
+    "FlowLayout": 2.34,
+    "FocusRequester": 2.84,
+    "Gestures": 2.62,
+    "GraphicsLayer": 2.46,
+    "GridsExtra": 1.33,
+    "Icons": 1.3,
+    "Images": 16.61,
+    "Interaction": 1.44,
+    "InteractionSource": 2.87,
+    "Layout": 2.04,
+    "LazyColumn": 3.46,
+    "LazyExtra": 2.85,
+    "LazyGrid": 1.62,
+    "Lists": 2.33,
+    "M3Misc": 1.67,
+    "MaterialSymbols": 2.91,
+    "ModShortcuts": 1.87,
+    "Modifiers": 2.3,
+    "NavRails": 1.35,
+    "Navigation": 1.68,
+    "Navigation3": 2.25,
+    "Pager": 1.0,
+    "Path": 3.56,
+    "Pickers": 19.47,
+    "PointerInput": 2.77,
+    "Recomposition": 1.48,
+    "Remember": 1.72,
+    "Scroll": 2.78,
+    "Search": 5.27,
+    "Shadows": 1.53,
+    "Shapes": 1.31,
+    "Sheets": 1.4,
+    "Tabs": 1.77,
+    "Text": 3.08,
+    "TextField": 1.93,
+    "Widgets": 2.2
+  }
+}

scripts/parity/parity.py

@@ -1,20 +1,23 @@
 #!/usr/bin/env python3
 """
-Parity harness — render every demo screen on the NATIVE (SDL/Skia) stack and on
+Parity harness - render every demo screen on the NATIVE (SDL/Skia) stack and on
 the JVM upstream-Compose stack, then pixel-diff them per screen.
 
 The two stacks share the exact same commonMain screen composables, so a screen
 that suddenly diverges from its usual difference level is a PORT REGRESSION
 (missing content, wrong shape/colour, broken clip). Absolute pixel-perfection
-is NOT the goal — fonts differ between stacks, so text-heavy screens carry a
+is NOT the goal - fonts differ between stacks, so text-heavy screens carry a
 steady baseline difference. The signal is the RANKING: a screen that jumps from
 ~8% to ~60% different is the bug. Four of the renderer regressions this project
 hit would have surfaced here.
 
 Usage (from repo root):
-    python scripts/parity/parity.py                 # all screens
+    python scripts/parity/parity.py                 # all screens, host's native target
     python scripts/parity/parity.py Buttons Shapes  # a subset
     python scripts/parity/parity.py --no-build      # reuse existing screenshots
+    python scripts/parity/parity.py --renderer=sdl3 # force the SDL leg (default on mingw;
+                                                    # on macOS/Linux this -Prenderer=sdl3 build)
+    python scripts/parity/parity.py --target=macosArm64   # cross/explicit native target
 
 Outputs to build/parity/ (gitignored):
     <pct>_<Name>_compare.png   native | jvm | amplified-diff, side by side
@@ -22,16 +25,42 @@ Outputs to build/parity/ (gitignored):
     report.txt                 ranked table
 The <pct> prefix is zero-padded so a plain file listing sorts worst-first.
 
-Windows-only for the native leg today (mingwX64 exe). Needs Pillow.
-Native uses the SDL renderer; pass --gpu to change.
+TARGET-AWARE (P0.1): the native leg runs on whatever host you invoke it from - Windows
+(mingwX64, always the SDL renderer), or macOS/Linux (default the Skia renderer, or the SDL
+renderer under --renderer=sdl3). macOS/Linux run BOTH renderers, so one Mac verifies both
+legs. Needs Pillow.
 """
-import subprocess, sys, os, shutil
+import subprocess, sys, os, shutil, platform, json
 from pathlib import Path
 from PIL import Image, ImageChops, ImageDraw
 
 REPO = Path(__file__).resolve().parents[2]
 OUT = REPO / "build" / "parity"
-NATIVE_EXE = REPO / "demo" / "build" / "bin" / "mingwX64" / "debugExecutable" / "demo.exe"
+
+# native target -> (gradle link-task suffix, K/N executable filename).
+TARGETS = {
+    "mingwX64":   ("MingwX64",   "demo.exe"),
+    "macosArm64": ("MacosArm64", "demo.kexe"),
+    "macosX64":   ("MacosX64",   "demo.kexe"),
+    "linuxX64":   ("LinuxX64",   "demo.kexe"),
+    "linuxArm64": ("LinuxArm64", "demo.kexe"),
+}
+
+
+def host_target() -> str:
+    s, m = platform.system(), platform.machine().lower()
+    arm = m in ("arm64", "aarch64")
+    if s == "Windows": return "mingwX64"
+    if s == "Darwin":  return "macosArm64" if arm else "macosX64"
+    if s == "Linux":   return "linuxArm64" if arm else "linuxX64"
+    raise SystemExit(f"parity: unsupported host {s}/{m}")
+
+
+def native_exe(target: str) -> Path:
+    _, exe = TARGETS[target]
+    return REPO / "demo" / "build" / "bin" / target / "debugExecutable" / exe
+
+
 WIDTH, HEIGHT = 1000, 700
 # Per-channel tolerance: below this a pixel counts as "same" (JPEG-ish noise,
 # sub-pixel AA, font hinting). Tuned so unrelated screens sit well under it.
@@ -45,26 +74,50 @@ def run(cmd, **kw):
     return subprocess.run(cmd, cwd=REPO, **kw)
 
 
-def build():
-    run([GRADLEW, ":demo:linkDebugExecutableMingwX64", "--console=plain"], check=True)
+def build(target: str, renderer: str):
+    suffix, _ = TARGETS[target]
+    cmd = [GRADLEW, f":demo:linkDebugExecutable{suffix}", "--console=plain"]
+    # macOS/Linux pick the renderer at BUILD time via -Prenderer; mingw is always sdl3
+    # (no property needed, and omitting it keeps the default Windows invocation stable).
+    if renderer == "sdl3" and target != "mingwX64":
+        cmd.append("-Prenderer=sdl3")
+    run(cmd, check=True)
 
 
 def jvm_shots(dst: Path):
     run([GRADLEW, ":demo:run", f"--args=--screenshot-all={dst}", "--console=plain"], check=True)
 
 
-def native_shot(name: str, dst: Path, gpu: str):
+def native_shot(name: str, dst: Path, exe: Path, gpu: str):
     bmp = dst / f"{name}.bmp"
-    run([str(NATIVE_EXE), f"--screen={name}", f"--screenshot={bmp}",
-         f"--gpu={gpu}", f"--width={WIDTH}", f"--height={HEIGHT}"],
-        check=False, timeout=60)
+    cmd = [str(exe), f"--screen={name}", f"--screenshot={bmp}",
+           f"--width={WIDTH}", f"--height={HEIGHT}"]
+    if gpu:  # runtime driver within the renderer; omit to let the app pick its default
+        cmd.append(f"--gpu={gpu}")
+    run(cmd, check=False, timeout=60)
     if bmp.exists():
         Image.open(bmp).convert("RGB").save(dst / f"{name}.png")
         bmp.unlink()
 
 
+def align_native(native: Image.Image, jvm: Image.Image) -> Image.Image:
+    """Normalise the native render to the JVM reference's dimensions.
+
+    The native leg draws at the machine's physical pixel density (2000x1400 on a
+    Retina Mac, DPR 2.0), while the JVM ImageComposeScene reference is fixed at
+    density 1.0 (1000x700). Both represent the SAME 1000x700-dp viewport, so a
+    proportional comparison must resize native down to the reference size rather
+    than crop it (a top-left crop would compare only a 2x-magnified quarter — the
+    old behaviour, invisible on Windows where both legs were already 1000x700).
+    A no-op when the sizes already match."""
+    if native.size != jvm.size:
+        return native.resize(jvm.size, Image.LANCZOS)
+    return native
+
+
 def diff_pair(native: Image.Image, jvm: Image.Image):
     """Return (percent_differing, amplified_diff_image)."""
+    native = align_native(native, jvm)
     w = min(native.width, jvm.width)
     h = min(native.height, jvm.height)
     a = native.crop((0, 0, w, h)).convert("RGB")
@@ -80,6 +133,7 @@ def diff_pair(native: Image.Image, jvm: Image.Image):
 
 
 def side_by_side(native, jvm, diff, path):
+    native = align_native(native, jvm)
     w = min(native.width, jvm.width)
     h = min(native.height, jvm.height)
     canvas = Image.new("RGB", (w * 3 + 20, h + 20), (16, 16, 16))
@@ -89,11 +143,51 @@ def side_by_side(native, jvm, diff, path):
     canvas.save(path)
 
 
+# P0.4 (RENDERER.md §8): per-(target/renderer) golden baselines so parity GATES
+# (non-zero exit) instead of only ranking. A screen regresses if it exceeds its baseline by
+# more than max(ABS_MARGIN pts, baseline*REL_MARGIN) - tolerant of run-to-run AA jitter,
+# strict on a real jump. `--update-baselines` reseeds the current target/renderer.
+BASELINES = REPO / "scripts" / "parity" / "baselines.json"
+ABS_MARGIN = 3.0   # percentage points
+REL_MARGIN = 0.25  # +25% of the baseline
+
+
+def load_baselines() -> dict:
+    if BASELINES.exists():
+        try:
+            return json.loads(BASELINES.read_text(encoding="utf-8"))
+        except Exception:
+            print("parity: baselines.json unreadable - treating as empty", file=sys.stderr)
+    return {}
+
+
+def threshold(base: float) -> float:
+    return base + max(ABS_MARGIN, base * REL_MARGIN)
+
+
 def main():
     argv = [a for a in sys.argv[1:] if not a.startswith("--")]
     flags = [a for a in sys.argv[1:] if a.startswith("--")]
     no_build = "--no-build" in flags
-    gpu = next((f.split("=", 1)[1] for f in flags if f.startswith("--gpu=")), "sdl3")
+    target = next((f.split("=", 1)[1] for f in flags if f.startswith("--target=")), host_target())
+    if target not in TARGETS:
+        print(f"parity: unknown --target={target} (known: {', '.join(TARGETS)})", file=sys.stderr)
+        return 2
+    # Renderer: mingw is always SDL; macOS/Linux default to Skia unless --renderer=sdl3.
+    renderer = next((f.split("=", 1)[1] for f in flags if f.startswith("--renderer=")),
+                    "sdl3" if target == "mingwX64" else "skia")
+    # Runtime GPU driver: default "sdl3" for the SDL renderer; omit for Skia (app default,
+    # e.g. Metal on macOS). Explicit --gpu= always wins.
+    gpu = next((f.split("=", 1)[1] for f in flags if f.startswith("--gpu=")),
+               "sdl3" if renderer == "sdl3" else "")
+    exe = native_exe(target)
+    update_baselines = "--update-baselines" in flags
+    baseline_key = f"{target}/{renderer}"
+    baselines = load_baselines()
+    base_for_key = baselines.get(baseline_key, {})
+    print(f"parity: target={target} renderer={renderer} gpu={gpu or '(default)'} exe={exe}")
+    print(f"parity: baseline key '{baseline_key}' - {len(base_for_key)} screen(s) baselined"
+          f"{'  [--update-baselines: WILL RESEED]' if update_baselines else ''}")
 
     OUT.mkdir(parents=True, exist_ok=True)
     jvm_dir = OUT / "_jvm"
@@ -103,13 +197,13 @@ def main():
         old.unlink()
 
     if not no_build:
-        build()
+        build(target, renderer)
         if jvm_dir.exists():
             shutil.rmtree(jvm_dir)
         jvm_dir.mkdir(parents=True)
         jvm_shots(jvm_dir)
 
-    # Screen set: the JVM run enumerates the full registry → use its PNGs as the
+    # Screen set: the JVM run enumerates the full registry -> use its PNGs as the
     # source of truth for names (native takes one exe launch each).
     names = sorted(p.stem for p in jvm_dir.glob("*.png"))
     if argv:
@@ -123,7 +217,7 @@ def main():
     for name in names:
         jvm_png = jvm_dir / f"{name}.png"
         if not no_build or not (OUT / f"{name}.native.png").exists():
-            native_shot(name, OUT, gpu)
+            native_shot(name, OUT, exe, gpu)
             src = OUT / f"{name}.png"
             if src.exists():
                 src.replace(OUT / f"{name}.native.png")
@@ -134,21 +228,53 @@ def main():
         native = Image.open(native_png).convert("RGB")
         jvm = Image.open(jvm_png).convert("RGB")
         pct, amp = diff_pair(native, jvm)
-        # Zero-padded pct prefix → worst-first in any file listing.
+        # Zero-padded pct prefix -> worst-first in any file listing.
         prefix = f"{pct:06.2f}"
         amp.save(OUT / f"{prefix}_{name}_diff.png")
         side_by_side(native, jvm, amp, OUT / f"{prefix}_{name}_compare.png")
         results.append((name, pct))
         print(f"  {name:28s} {pct:6.2f}% differing")
 
+    # --update-baselines: write the current run as the golden baseline for this key.
+    if update_baselines:
+        baselines[baseline_key] = {n: round(p, 2) for n, p in results if p is not None}
+        BASELINES.write_text(json.dumps(baselines, indent=2, sort_keys=True) + "\n", encoding="utf-8")
+        print(f"\nparity: reseeded {len(baselines[baseline_key])} baseline(s) for "
+              f"'{baseline_key}' -> {BASELINES}")
+        return 0
+
     results.sort(key=lambda r: (-1 if r[1] is None else r[1]), reverse=True)
-    lines = ["screen                        %differ", "-" * 40]
+    regressions = []
+    lines = [f"screen                        %differ   baseline   verdict  ({baseline_key})", "-" * 66]
     for name, pct in results:
-        lines.append(f"{name:28s}  {'NATIVE FAILED' if pct is None else f'{pct:6.2f}%'}")
+        base = base_for_key.get(name)
+        if pct is None:
+            verdict = "NATIVE FAILED"
+            regressions.append(name)
+            lines.append(f"{name:28s}  {'-':>7}   {base if base is None else f'{base:6.2f}%':>8}   {verdict}")
+            continue
+        if base is None:
+            verdict = "(no baseline)"
+        elif pct > threshold(base):
+            verdict = f"REGRESSION (+{pct - base:.2f})"
+            regressions.append(name)
+        else:
+            verdict = "ok"
+        base_s = "   -   " if base is None else f"{base:6.2f}%"
+        lines.append(f"{name:28s}  {pct:6.2f}%   {base_s:>8}   {verdict}")
     report = "\n".join(lines)
     (OUT / "report.txt").write_text(report + "\n", encoding="utf-8")
     print("\n" + report)
     print(f"\nDiff images + report in {OUT}")
+
+    if not base_for_key:
+        print(f"\nparity: NO baselines for '{baseline_key}' - not gating. "
+              f"Seed with:  python scripts/parity/parity.py --update-baselines")
+        return 0
+    if regressions:
+        print(f"\nparity: FAIL - {len(regressions)} regression(s): {', '.join(regressions)}")
+        return 1
+    print(f"\nparity: PASS - no screen exceeds its baseline (+{ABS_MARGIN}pts / +{REL_MARGIN:.0%}).")
     return 0
 
 

scripts/verify-mac.sh

@@ -0,0 +1,141 @@
+#!/usr/bin/env bash
+# MAC-VERIFY runbook (P0.2, RENDERER.md) - the one-command gate for renderer work.
+#
+# Runs on macOS or Linux and exercises BOTH renderers:
+#   0. DRIFT-CHECK: vendor-clean (sync.py + diff src/vendor, P0.7) + manual-vendor
+#      provenance tripwire (P0.6)
+#   1. Build :demo + :apidemo for the host target        (Skia leg, then -Prenderer=sdl3)
+#   2. Run the interaction probes on each leg, gate on their PASS/FAIL output
+#   3. Run scripts/parity/parity.py for each leg         (gates on baselines.json when seeded)
+#   4. CDN_PROFILE draw-ms spot-check on LazyColumn/Tabs (fails on >20% regression vs the
+#      last recorded run; build/verify-mac/perf-baseline.txt, seeded on first run)
+#
+# Usage:
+#   scripts/verify-mac.sh                        # full run, non-zero exit on any failure
+#   scripts/verify-mac.sh --update-perf-baseline # re-seed the perf baseline first
+#
+# Notes:
+#   - Probes self-terminate on a frame counter; a hang means the leg is broken anyway.
+#   - Toggling -Prenderer= keys a separate Gradle configuration-cache entry; if the SDL
+#     leg fails with "couldn't find sdl3_ttf", rm -rf .gradle/configuration-cache (see
+#     CLAUDE.md "Common pitfalls") and re-run.
+
+set -u
+
+REPO="$(cd "$(dirname "$0")/.." && pwd)"
+cd "$REPO"
+
+# ============
+#  Host target
+case "$(uname -s)/$(uname -m)" in
+	Darwin/arm64)          TARGET=MacosArm64; EXE_DIR=macosArm64 ;;
+	Darwin/x86_64)         TARGET=MacosX64;   EXE_DIR=macosX64 ;;
+	Linux/aarch64)         TARGET=LinuxArm64; EXE_DIR=linuxArm64 ;;
+	Linux/x86_64)          TARGET=LinuxX64;   EXE_DIR=linuxX64 ;;
+	*) echo "verify-mac: unsupported host $(uname -s)/$(uname -m)" >&2; exit 2 ;;
+esac
+
+DEMO_EXE="demo/build/bin/$EXE_DIR/debugExecutable/demo.kexe"
+PROBES=(nav3test backtest clicktest scrolltest multiwintest)
+PERF_DIR="build/verify-mac"
+PERF_BASELINE="$PERF_DIR/perf-baseline.txt"
+mkdir -p "$PERF_DIR"
+[ "${1:-}" = "--update-perf-baseline" ] && rm -f "$PERF_BASELINE"
+
+FAILURES=()
+note() { echo; echo "==== verify-mac: $*"; }
+fail() { FAILURES+=("$1"); echo "verify-mac: FAIL - $1" >&2; }
+
+# ============
+#  Perf spot-check: run one screen for ~8s under the frame profiler, parse the last
+#  "draw=<avg>/<max>ms" line, compare avg against the recorded baseline (+20%, +0.2ms
+#  absolute guard so sub-ms values don't false-positive on noise).
+perf_check() { # $1=leg $2=screen
+	local leg="$1" s="$2"
+	local log="$PERF_DIR/profile_${leg}_${s}.log"
+	rm -f "$log"
+	note "[$leg] perf spot-check $s"
+	CDN_PROFILE="$log" CDN_FORCERENDER=1 "$DEMO_EXE" --screen="$s" &
+	local pid=$!
+	sleep 8
+	kill "$pid" 2>/dev/null
+	wait "$pid" 2>/dev/null
+	local avg
+	avg=$(tail -1 "$log" 2>/dev/null | grep -o 'draw=[0-9.]*' | head -1 | cut -d= -f2)
+	if [ -z "$avg" ]; then
+		fail "[$leg] perf $s (no profiler output in $log)"
+		return
+	fi
+	local base
+	base=$(grep "^$leg $s " "$PERF_BASELINE" 2>/dev/null | awk '{print $3}')
+	if [ -z "$base" ]; then
+		echo "$leg $s $avg" >> "$PERF_BASELINE"
+		echo "verify-mac: [$leg] $s draw=${avg}ms (baseline seeded)"
+	elif awk -v a="$avg" -v b="$base" 'BEGIN { exit !(a > b * 1.2 && a > b + 0.2) }'; then
+		fail "[$leg] perf $s regression: draw=${avg}ms vs baseline ${base}ms (+20% gate)"
+	else
+		echo "verify-mac: [$leg] $s draw=${avg}ms (baseline ${base}ms) ok"
+	fi
+}
+
+# ============
+#  One leg = build + probes + parity + perf.
+run_leg() { # $1=skia|sdl3
+	local leg="$1"
+	local props=()
+	[ "$leg" = "sdl3" ] && props=(-Prenderer=sdl3)
+
+	note "[$leg] build :demo + :apidemo ($TARGET)"
+	if ! ./gradlew ${props[@]+"${props[@]}"} ":demo:linkDebugExecutable$TARGET" \
+			":apidemo:linkDebugExecutable$TARGET" --console=plain; then
+		fail "[$leg] build"
+		return
+	fi
+
+	local p out
+	for p in "${PROBES[@]}"; do
+		note "[$leg] probe --$p"
+		out=$("$DEMO_EXE" "--$p" 2>&1 | tail -40)
+		if ! echo "$out" | grep -q "PASS"; then
+			echo "$out"
+			fail "[$leg] probe $p"
+		fi
+	done
+
+	note "[$leg] parity ($leg leg)"
+	python3 scripts/parity/parity.py --renderer="$leg" || fail "[$leg] parity"
+
+	# P2.2 memory soak: cycle every screen x6, assert current RSS doesn't ratchet up
+	# (regression guard for the snapshot-observation / dispose leak fixed in c59caf72).
+	note "[$leg] soak (memory)"
+	out=$(CDN_SOAK_CYCLES=6 "$DEMO_EXE" --soaktest 2>&1 | tail -5)
+	if ! echo "$out" | grep -q "soaktest: PASS"; then
+		echo "$out"
+		fail "[$leg] soak"
+	fi
+
+	perf_check "$leg" LazyColumn
+	perf_check "$leg" Tabs
+}
+
+# ============
+#  DRIFT-CHECK first (cheap, cross-platform): the legs must build from a vendor tree
+#  that matches the pinned refs, with no manual vendor lagging the pin.
+note "drift-check: vendor-clean (sync.py + diff src/vendor)"
+python3 scripts/compose-fork/check-vendor-clean.py || fail "drift-check: src/vendor drifted from the pinned refs"
+note "drift-check: manual-vendor provenance"
+python3 scripts/compose-fork/check-vendor-drift.py || fail "drift-check: a manual vendor lags the pinned ref"
+
+run_leg skia
+run_leg sdl3
+
+# ============
+#  Summary
+echo
+if [ ${#FAILURES[@]} -gt 0 ]; then
+	echo "verify-mac: FAILED (${#FAILURES[@]}):"
+	printf '  - %s\n' "${FAILURES[@]}"
+	exit 1
+fi
+echo "verify-mac: ALL GREEN (both legs: build + probes + parity + perf)"
+exit 0

utils/material-symbols/build.gradle.kts

@@ -47,8 +47,8 @@ val vHostSupportsMingw = rootProject.extra["vHostSupportsMingw"] as Boolean
 // material3 rides its own release train (same +dev build, different base).
 // Gradle orders "+dev" BELOW the plain version, so force the core-repo
 // groups on jvm configurations (mirrors :demo's forcing).
-val vComposeJvmVersion = "1.12.0-beta01+dev4324"
-val vComposeM3JvmVersion = "1.12.0-alpha03+dev4324"
+val vComposeJvmVersion = libs.versions.compose.get()
+val vComposeM3JvmVersion = libs.versions.composeMaterial3.get()
 val vComposeJvmForced = mapOf(
     "org.jetbrains.compose.runtime" to vComposeJvmVersion,
     "org.jetbrains.compose.ui" to vComposeJvmVersion,
@@ -79,7 +79,7 @@ kotlin {
         commonMain.dependencies {
             // The official runtime klibs — the SAME artifact/version the port
             // itself uses (:ui pins it); resolves for metadata, jvm AND native.
-            api("org.jetbrains.compose.runtime:runtime:1.11.1")
+            api("org.jetbrains.compose.runtime:runtime:${libs.versions.composeRuntime.get()}")
             // Official Maven coordinates for the API surface (Modifier / Color
             // / Dp / material3's LocalContentColor). Metadata + jvm resolve
             // them from Maven; NATIVE configurations substitute them for