[Frameforge 6] Qualify unchanged AOT editor, 60 Hz interaction and distributable media runtime

[danwalmsley]

Dependencies and outcome

Final gate after #54, #55, #56, #57, #58, #34 and #40. Replace the current compatibility preview with a qualified working macOS Native AOT app. Existing --verify intentionally fails when required media capabilities are absent; do not relax it to API presence or rendered-scene count.

Implementation and acceptance harness

• Pin original application/source hashes and bundled demo assets; preserve application JS/WGSL and third-party notices. Build a repeatable acceptance harness with real UI gestures plus inspected app state, runtime/GPU error collection and independent pixel/audio/export checks.
• Startup: await app.ready and app.booted, WebGPU renderer, seven-clip demo and actual decoded visible content. No console/JS/device errors, blank viewer or silently skipped external video layers.
• Editorial: source/project view, play/pause/J-K-L, frame step, repeated seek across cuts/dissolves, trim/split/reorder, undo/redo, transforms/color/crop, editable title overlays, timeline zoom/pan and window/sidebar resizing. Check project state and output frames, not only handler calls.
• Media/files: import video/audio/still, waveform generation, source in/out, audio gain/fade/mute, restart recovery, portable save/open and reference relink. Qualify PNG, SRT/EDL, recorded movie and export cancellation with independent file decode/validation. Native select popup gaps are tracked by Implement real popup selection for collapsed HTML select controls #44; link any additional blocking UI gaps rather than patching the sample.
• Compare Chrome using identical assets, viewport, scale, resolution and hardware. Measure input-to-present latency, present intervals, missed vsyncs, decode/JS/layout/paint/GPU submission/completion and retained-image queues separately. A 24 fps clip may repeat frames on a 60 Hz display; do not count those intended repeats as stalled UI or claim CPU submission time is measured FPS.
• Proposed macOS 60 Hz gate: warmed 1080p preview with timeline/sidebar drag and playback, >=99% of measured interaction frames meeting the 16.67 ms presentation deadline over a repeatable 30-second trace; publish p50/p95/p99 and missed-vsync counts. Investigate any sustained drops or material Chrome gap before passing, and record agreed workload/threshold revisions. No per-frame CPU readback, unbounded queue or stale-frame stretching as a performance workaround.
• Run repeated create/close, playback/seek/resize, device loss and export/cancel stress; verify memory/decoder/texture/worker counts return to bounded baselines.
• Publish Native AOT with warning gate, retain main Avalonia 11 regressions and sample Avalonia 12 cooperative resize. Package matching V8 snapshots, Dawn, codecs and assets; validate dependencies from a clean bundle, real process name Frameforge and clean shutdown. State signing/notarization, native library/static-link layout and platform coverage honestly.

Completion checklist

• Original full workflow above passes with screenshots, traces and decoded output evidence.
• WPT/CTS project profile names, exact commands and pass/skip/fail counts attached; no unsupported path counted as success.
• 60 Hz interaction and bounded-resource gates pass on declared hardware, compared with Chrome.
• Downloadable macOS AOT app/ZIP runs without .NET, Node or developer SDK search paths.
• Windows/Linux parity remains separately tracked until tested; no cross-platform qualification implied.

Original application references

• README.md
• tests/browser-smoke.py
• tests/gpu-smoke.html
• TEST_REPORT.md

Shared delivery requirements

Parent: #53. Baseline: PR #43 / ce56d49; sample experiments/WebScene.Frameforge.
Reference application: https://github.com/wieslawsoltes/Frameforge (pin f414cd44896b659a5c6da2e4fc596a2ded055f2a, includes demo media and THIRD_PARTY_NOTICES.md).
Implement in WebScene, leaving original application JavaScript/WGSL unchanged. No fake capability objects, synthetic successful events or swallowed errors. Keep public contracts cross-platform with isolated backend implementations; qualify macOS arm64 first and explicitly track Windows/Linux follow-up. Production Avalonia 11 must remain supported; only samples opt into Avalonia 12. Native AOT/trim safety is mandatory.
Add focused native/managed regression coverage and a pinned WPT subset or clearly labeled project-owned contract for non-WebGPU behavior. Applicable WebGPU CTS cases belong with GPU work. Record exact revisions, test commands, negative cases and reproducible evidence in the implementation PR. Unsupported functionality cannot be marked passed; distinguish app coverage from standards conformance. Review existing implementation before adding overlapping infrastructure.

Native file acceptance clarification

Qualify Open/Import and Save/Save As through the actual Avalonia and Uno backend picker services from #57. For portable projects, PNG, SRT/EDL and movies, verify native dialog ownership, suggested name/type, chosen destination, overwrite/cancel/error behavior and saved bytes. Browser download UI or silently writing to Downloads does not satisfy this gate. macOS-first runtime qualification remains valid, but an unavailable Uno/platform test must be recorded as unverified until exercised.