[AZ-461] [AZ-464] [AZ-470] [AZ-472] Batch 5 - detection/bulk-validate/panel-width/classes tests

- AZ-461 sync image detect URL canary (FT-P-11) PASS;
  async-video QUARANTINE (FT-P-12) + X-Refresh-Token drift
  (FT-P-13) recorded as it.fails() with controls.
- AZ-464 bulk-validate URL + UI sync (≤2 s) PASS;
  body shape drift {annotationIds,status} vs contract
  {ids,targetStatus:30} captured as it.fails().
- AZ-470 panel-width debounce + rehydration: entire task
  is Phase-B target (useResizablePanel has no PUT writer
  / no rehydration); 3 ACs as it.fails() with controls.
- AZ-472 DetectionClasses load + click + fallback PASS;
  hotkey arithmetic P=0 PASS, P=20/P=40 it.fails() for
  classes[idx+P]-against-dense-array drift.

Code review: PASS (0 findings). Fast: 18/18 files,
102 passed / 13 skipped. Static: 21/21 PASS.

Co-authored-by: Cursor <cursoragent@cursor.com>

_docs/02_tasks/done/AZ-461_test_detection_endpoints.md

@@ -0,0 +1,62 @@
+# Test — Detection Endpoints (Sync / Async / Long-Video)
+
+**Task**: AZ-461_test_detection_endpoints
+**Name**: Detection endpoints — sync image + async video (Phase B target) + long-video header
+**Description**: Implement the three blackbox tests that exercise the `detect/` service's three detection paths from the SPA: sync image detect (FT-P-11), async video detect SSE (FT-P-12, quarantined as Phase B target), and the `X-Refresh-Token` header carried on long-video detect (FT-P-13).
+**Complexity**: 2 points
+**Dependencies**: AZ-456_test_infrastructure
+**Component**: 06_annotations (detection sub-surface) (Blackbox Tests)
+**Tracker**: AZ-461
+**Epic**: AZ-455
+
+## Problem
+
+Detection is multimodal: sync for images (today), async with SSE updates for video (Phase B per AC-25), and long-video has its own header contract for token rotation. Without targeted tests, regressions slip in mode-by-mode.
+
+## Outcome
+
+- 3 test scenarios are present in their declared profile and reference their `results_report.md` rows.
+- FT-P-12 is QUARANTINEd in CI with a clear marker until the async-video path lands.
+
+## Scope
+
+### Included
+
+| Scenario | Profile | Source file | results_report row |
+|----------|---------|-------------|--------------------|
+| FT-P-11 — sync image detect endpoint | fast + e2e | blackbox-tests.md | per FT-P-11 |
+| FT-P-12 — async video detect endpoint + SSE (target — Phase B) | fast (quarantined) | blackbox-tests.md | per FT-P-12 |
+| FT-P-13 — long-video detect carries `X-Refresh-Token` header | fast | blackbox-tests.md | per FT-P-13 |
+
+### Excluded
+
+- Annotation save after detect (covered in 05_test_annotations_endpoint).
+- Detection class CRUD (covered in 17_test_detection_classes).
+
+## Acceptance Criteria
+
+**AC-1: Sync image detect URL + body**
+FT-P-11 asserts the outbound POST URL + body shape for sync image detect against the contract.
+
+**AC-2: Async video detect — quarantined**
+FT-P-12 is implemented and registered, but marked `Result: QUARANTINE` in the CSV report until AC-25 (Phase B) lands. The test code itself runs (does not just `xit`) and produces a clear log entry "FT-P-12 awaits AC-25 / async video detect impl".
+
+**AC-3: Header carried**
+FT-P-13 asserts every long-video detect request carries the `X-Refresh-Token` header.
+
+## System Under Test Boundary
+
+- System under test: the SPA's `<AnnotationsPage>` (or its detect-trigger sub-component) + `src/api/client.ts`.
+- Allowed stubs: MSW for `/api/detect/*` (fast); real `detect/` service (e2e — async video path stays quarantined until the suite has it).
+- Disallowed: stubbing the SPA components or constructing the request manually from a unit test.
+- Expected observables per `results_report.md` rows for FT-P-11, 12, 13.
+
+## Constraints
+
+- FT-P-12 is QUARANTINE in CI, NOT skipped — the result must appear in the report with that status, traceable to AC-25.
+
+## Risks & Mitigation
+
+**Risk 1 — Async video detect path lands while tests are being implemented**
+- *Risk*: AC-25 may go from target to shipped, flipping FT-P-12 from QUARANTINE to PASS / FAIL.
+- *Mitigation*: FT-P-12 reads the runtime UI to detect whether the path exists; the QUARANTINE marker is conditional on absence.