Webcam resource validation + first-frame proof + CameraConflictProbe: MediaCaptureFrameSource validates post-init (VideoDeviceId match, stream properties, reader StartAsync status), subscribes Failed/CameraStreamStateChanged → SourceFailed; CameraManager.AcquireAsync requires first-frame proof (4s timeout) — silent empty box impossible; MainViewModel surfaces WebcamError chip + MessageBox with suspect-app names; fallback ladder VideoPreview → VideoRecord; 19041 SDK projection gaps documented; AGENTS.md + schema.md + HANDOFF.md memory-map rules added; 81 tests passing, 0 warnings

AGENTS.md

@@ -30,7 +30,12 @@ conventions live here and in `ai.md`.
 1. [`schema.md`](schema.md) — the memory-map conventions (what lives where, how to keep it true).
 2. [`ai.md`](ai.md) — the AI guide: architecture, patterns, decisions, current state.
 3. [`TASKS.md`](TASKS.md) — the task queue + authoritative YouTube API research.
-4. `<dir>/index.md` — the index for any directory you're about to touch.
+4. [`HANDOFF.md`](HANDOFF.md) — current operational state: what's in flight, landmines, next step.
+5. `<dir>/index.md` — the index for any directory you're about to touch.
+
+**If `HANDOFF.md` exists, trust it as current state** — no `fsck`, no branch
+hunting, no file-scanning to re-derive what it already states, unless it points
+at a problem.
 
 ## Working rules
 
@@ -38,6 +43,12 @@ conventions live here and in `ai.md`.
   and the map gets fixed in the same change (stale facts are corrected, not appended).
 - **Every feature change ships with its memory update:** `ai.md` for
   architecture/patterns, `TASKS.md` for status, index files when layout changes.
+- **Rewrite `HANDOFF.md` at session end, compaction, or any interruption.**
+  Never end a session with uncommitted work unrecorded — the handoff names the
+  branch, the dirty files, and why it stopped.
+- **The first time a fact costs a hunt (secrets path, DB path, port, recovery
+  source), record it** in `ai.md`/indexes/`HANDOFF.md` so the next session never
+  re-hunts it.
 - **Follow existing conventions** — MVVM, `RelayCommand` for actions,
   `ViewModelBase.SetProperty<T>()`, all styles in `Themes/Controls.xaml`
   (merged once in `App.xaml`; never duplicate per-window).