feat: GPUI desktop port foundation

- scene crate: full project/scene/element model, serde round-trip
  proven against the web SerializedProject shape
- transfer crate: .ocp zip container, cross-compat with web fflate
  archives proven in both directions
- storage crate: filesystem project store replacing IndexedDB,
  .ocp import/export
- media crate: ffmpeg-next 8 decoder (frames, audio, thumbnails,
  waveform summaries)
- playback crate: wall-clock anchored, frame-rounded playback clock
- gpu crate: native texture readback; compositor renders headless
  offscreen on Vulkan (spike test)
- flake devshell: rust toolchain, GPUI native deps, ffmpeg dev,
  bindgen clang args; GPUI hello-world builds
- port plan in notes/gpui-port.md

1 files changed, 20 insertions, 10 deletions

diff --git a/notes/roadmap.md b/notes/roadmap.md
index c886edeb..fc89bb46 100644
--- a/notes/roadmap.md
+++ b/notes/roadmap.md
@@ -1,10 +1,21 @@
 # Roadmap & session notes
 
 Working notes for the fork's development direction. Captured 2026-07-26,
-updated 2026-07-27 (roadmap feature slices implemented, last commit
-`9c3b788b`).
+updated 2026-07-28 (GPUI desktop port greenlit — see notes/gpui-port.md).
 
-## Done
+## Done (2026-07-28 session)
+
+- Freeze-duration prompt removed; freeze frame uses a fixed 3s (store, dialog, and test deleted).
+- Ripple-extend: dragging the right edge of a static element (image/freeze still/text, i.e. no `sourceDuration`) past its neighbor pushes the whole right-hand chain on that track. Same undo step as the resize; live during drag. Video/audio keep clamping. Core: `timeline/group-resize/compute-resize.ts` + `rightPushChain` from `resize-controller.ts`.
+- Timeline filmstrip: video elements render real per-position thumbnails, density adapts to zoom (power-of-two interval snapping). New `services/thumbnail-cache/` (LRU, batched mediabunny decode) + `timeline/components/video-filmstrip.tsx`. Images unchanged. Verified in browser by agent (distinct tiles, zoom density, viewport clipping, cache clear on media delete).
+- Export hardening (`services/renderer/scene-exporter.ts`, `export-encoding.ts`): bitrate is fps-aware (`w*h*fps*bpp`, high = 0.2 bpp → ~12.4 Mbps at 1080p30, was ~6 fps-blind); keyframe every 2s; export canvas rounded to even dims. A capture-timing change (wait past WebGPU present before snapshot) was tried and REVERTED the same day — the canvas is blank after present, export came out black. Synchronous same-task snapshot is the correct behavior for WebGPU canvases; the temporal-ghosting hypothesis is dead. Colorspace tagging: no API exists (verified mediabunny + lib.dom) — BT.709 vs 601 is Chrome's encoder's call.
+- MP4 export: ffmpeg.wasm + libx264 was implemented (chunked rawvideo → x264 CRF ladder) and then REVERTED at the owner's request after two wasm-side bugs (x264 auto-threading spawns 28 pthreads and hangs the worker — `-threads 4` fixes it; `@ffmpeg/ffmpeg` `writeFile` transfers/detaches the input ArrayBuffer, so chunk buffers must be single-use). The investigation notes stay here in case the idea is revisited; WebM/VP9 export is the owner's daily path and works well. MP4 stays on the mediabunny/WebCodecs avc path (which undershoots bitrate on this machine — OpenH264 ignores bitrateMode, has no quantizer mode, no hardware encoder exists; probe-verified 2026-07-28).
+- Encoder investigation (2026-07-28, probe-verified in the user's Helium): NO hardware H.264 encode exists on the machine; Chrome's OpenH264 ignores `bitrateMode` (byte-identical VBR/CBR output), has no AVC quantizer mode (`isConfigSupported` false), and undershoots to ~0.6 Mbps on real content regardless of configured bitrate (6-50 Mbps). WebCodecs H.264 is a dead end for quality export; x264 via wasm is the only in-browser path. The fps-aware `computeVideoBitrate` still serves the WebM path.
+- Next dev overlay disabled (`devIndicators: false` in `apps/web/next.config.ts`).
+- Gates green: bun test 316 pass / 1 skip, tsc, eslint on touched files, `bun build:web`.
+- Human verification still owed: freeze + ripple-extend click-through by owner.
+
+## Done (2026-07-26/27 session)
 
 - Freeze frame at playhead (snowflake button), composite canvas capture.
 - Freeze frame is a single undo step (`BatchCommand` + `ShiftSplitRemainderCommand`).
@@ -69,13 +80,12 @@ work. The GPUI desktop app sidesteps it entirely (native GPU).
 5. ~~Voice-over recording~~ done.
 6. ~~Git-like project versioning~~ done (v1). v2 candidates: diff view,
    branches, content-addressed media dedup, shipping history inside `.ocp`.
-7. **Self-contained binary, first-class Linux + BSD.** `apps/desktop` (GPUI)
-   is the vehicle but is a hello-world scaffold today; porting the editor is
-   a large effort. Caveat: GPUI's Linux support is young; BSD support is
-   unproven — spike before committing. Browser version stays regardless
-   (editing in a browser is a feature, not a compromise). Distribution:
-   AppImage/GitHub releases first; Flathub is effectively closed to us (June
-   2026 policy bans AI-assisted code in new submissions).
+7. ~~Self-contained binary, first-class Linux + BSD.~~ **GREENLIT
+   2026-07-28: full 1:1 GPUI port, Linux-first.** Decisions: in-process
+   ffmpeg (`ffmpeg-next`) for decode+encode, x264 for H.264 (licensing
+   waived, quality first), no server backend (project store moves to
+   filesystem), web version stays. BSD parked (GPUI unproven there).
+   Full plan: notes/gpui-port.md.
 
 ## Deprioritized / parked