**Phase 134 final verification pass — all green** (all 3 task files already in `complete/`; no implementation was missing) - Verified: 5-state `SyncStatus` + `cancelled` terminal (error None, final counts kept), `POST /api/sync/cancel` (202/409/403), cooperative `_check_cancelled` boundaries, shutdown `CancelledError` contract preserved, `#sync-cancel-btn` show/hide + neutral "Sync cancelled" settle, 8-branch poll tree, re-attach — code, unit, integration, and E2E layers all present - `uv run pytest --cov=app --cov-report=term-missing` → **3150 passed**, `app/` coverage **99%** (gate: >90%) - `uv run pytest tests/e2e/test_sync_cancel.py -v --no-cov` (isolated) → **3 passed** (47.6 s) - `uv run ruff check .` → clean; `uv run pyright` → 0 errors, 0 warnings **Completion criteria:** ① cancel endpoint 202/409/403 ✅ (unit + E2E) ② `cancelled` terminal reported by status, error null, counts kept ✅ (integration `test_cancel_mid_run_lands_in_cancelled_then_resyncs_clean`) ③ unrequested-cancel pin ✅ (`test_unrequested_cancel_is_never_swallowed_and_never_converts`) ④ UI lifecycle + clean re-sync (sentinel row, full 40-file import) ✅ (E2E) ⑤ suite/coverage/E2E gates ✅ ⑥ uncancelled runs byte-identical ✅ (all 3150 pre-existing tests green untouched) - Docs: README.md reviewed in full against code (pages, auth endpoints, every config default vs `app/config.py`, palette 9+8, fail-loud, cancel section) — consistent, no changes needed. AGENTS.md: fixed one pre-existing inaccuracy (rule 2 "move its file" → "move its directory" — phases are directories); everything else verified accurate - No live infrastructure touched; no deviations **Next pending phase:** `135_git_source_branch`