feat: reveal all hidden shapes with Shift+H, release SAM3 VRAM on idle and on demand (REQ-191, REQ-192)

docs/tasks.md

@@ -1565,6 +1565,59 @@ read it.
   frame already holding an overlapping truck → banner `skipped K overlapping truck`, dot, count
   unchanged, while a frame holding a truck elsewhere gets its own second box.
 
+## Task — Reveal all hidden shapes with Shift+H (REQ-191) `[DONE]`
+
+- `frontend/src/pages/ReviewPage.jsx` — third piece of hide state, `revealAll`, is a boolean
+  **overlay**: `isShapeVisible` answers yes for everything while it is on, and neither
+  `hiddenShapeIds` nor `hiddenClasses`/`overriddenShapeIds` is touched, which is what makes the
+  second `Shift+H` restore the previous hidden state exactly. In the keydown handler,
+  `Shift+H` toggles the overlay, a plain `H` clears an active overlay first (so it edits the
+  real hidden state) and otherwise falls through to `toggleHideSelected()`.
+- `frontend/src/components/ReviewSidebar.jsx` — `revealing hidden` chip (SVG `EyeIcon`, accent
+  pill, `title` naming `Shift+H`) in the *Shapes on this frame* header while the overlay is on;
+  dimming of rows is unchanged, so the chip and the dims together say what is actually hidden.
+- `frontend/src/components/ShortcutsPanel.jsx` — `Shift+H` row next to `H`.
+- `frontend/src/app.css` — `.reveal-chip` on `--accent` tokens (works in both themes).
+- Docs: `requirements.md` REQ-191, `design.md` sidebar block, `ui-spec.md` keyboard table +
+  shapes-panel bullet.
+→ verify: **[DONE]** `npm run build` green; `git diff --check` clean. **Still needs a browser
+  pass:** hide a class and one shape, `Shift+H` → both drawn + chip up, `Shift+H` again → back
+  to the same dims, plain `H` → overlay drops and only then hides the selection.
+
+## Task — Free SAM3's VRAM on idle and on demand (REQ-192) `[DONE]`
+
+- Question answered first: nothing freed the model before — `release_engine()` had exactly one
+  caller (`backend/training.py`, REQ-065), so the ~3.9 GB stayed in the card until a training
+  run or the process exited. The YOLO loads elsewhere are transient locals, no leak found.
+- `backend/sam3_engine.py` — `IDLE_UNLOAD_S` (env `SAM3_IDLE_UNLOAD_S`, default 1200, `0`
+  disables), `_touch()` stamped by `get_engine()` and by the four model methods that actually
+  run inference (so a long autolabel job counts as use, not as idle), and one daemon watcher
+  started on first `get_engine()`: every `min(60 s, IDLE_UNLOAD_S)` it releases the engine,
+  but only after taking `jobs.gpu_lock` **without blocking** — a job or assist in flight just
+  postpones the release, never gets interrupted (same one-holder rule as REQ-065).
+- `backend/api/sam3.py` — `POST /api/sam3/release`: same non-blocking `gpu_lock`, `409` while
+  the GPU is busy, `{"released", "model_loaded"}` otherwise; wired in `backend/main.py`.
+- `docker-compose.yml` + `.env.example` — the variable is passed through, so the container
+  sees a value set in `.env` (empty/unset → Python falls back to 1200).
+- `frontend/src/components/Sidebar.jsx` + `api.js` + `roboflow.css` — badge is now three-state:
+  `SAM3: Loaded` (green **button**, click releases, optimistic flip, 3 s poll confirms) /
+  `SAM3: Idle` / `SAM3: Off`; a failed release shows its `detail` for 4 s instead of failing
+  silently.
+- Docs: `requirements.md` REQ-192, `design.md` module row + API contract, `ui-spec.md` badge
+  block, `.env.example` GPU section.
+→ verify: **[DONE]** `uv run python /tmp/opencode/test_idle_unload.py` — ALL PASS: unload after
+  idle, release postponed while `gpu_lock` held then fires, `0` disables the watcher, endpoint
+  answers `409` when busy and `{"released": true, "model_loaded": false}` when free; app imports
+  with `/api/sam3/release` in the OpenAPI paths; `npm run build` green; `git diff --check` clean.
+  **Live run against the rebuilt container:** assist on a batch frame loads the model (VRAM free
+  7.39 → 3.15 GB), `POST /api/sam3/release` answers `{"released": true, "model_loaded": false}`
+  and VRAM goes back to 7.32 GB (+4.2 GB freed), the next assist rebuilds in 6 s and works,
+  badge strings present in the served `index-BGbzE_yy.js`. Container env shows
+  `SAM3_IDLE_UNLOAD_S` empty → falls back to the 1200 s default as designed. **Watcher verified
+  live too:** with `SAM3_IDLE_UNLOAD_S=10` on one container run, a loaded model (3.15 GB free)
+  went to `model_loaded: false` / 7.32 GB free on its own within the 10 s tick, then the
+  container was put back on the default 1200 s.
+
 ## Known open points
 
 - *Not closed by any task, by choice:* **any rebuild kills the running job.** Task 14's resume