Full frontend built against the synthetic API (no dependence on lanes A/B/D):
M4 — synchronized playback: master clock from performance.now() (never a <video>);
per-video correction via requestVideoFrameCallback (exact mediaTime) with a
currentTime+half-frame fallback — hard-seek >150ms / nudge playbackRate +/-5% 20-150ms /
lock <20ms; out-of-range videos pause+dim; single audio source; dev sync-error overlay.
Timebase mirrors config.py (lib/timebase.js). Verified: seek is exact to 0ms; continuous
inter-video desync 13ms mean / 46ms max.
M5 — 3D viewer: PLY point cloud, per-video camera paths + current-pose frusta, OrbitControls,
snap-to-camera (intrinsics->PerspectiveCamera fov) + free roam. All COLMAP->Three.js via the
frozen lib/pose.js; pose interpolation in lib/poseTrack.js (slerp+lerp of contract inputs).
M6 — anchor overlays: letterbox-correct per-video canvas; anchors projected via pose.js;
behind-camera cull. Projection agrees with an independent pinhole to 1.45e-13 px.
Timeline — colored event markers + legend, hover tooltip, click-to-jump; draggable scrubber.
Phase-3 seams (annotate.js M8, camPath.js M9) left as stubs. No frozen files edited; no new
deps; no change requests.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
ec22cbdf1f