phase: 187_sync_peak_memory_line

**Phase 187 — final verification pass: all criteria met, repo 100% green.**

Verified (all four tasks already in `complete/`)
- `app/core/memory.py`: `rss_mb` / `rss_peak_mb` / `cgroup_peak_mb` / `fmt_mb`, pure stdlib, never-raise, **100%** coverage, 24 branch tests.
- Lifecycle lines append-only: `sync: started … rss_mb=`, all three terminals `… rss_mb= rss_peak_mb=` (failed = sanitized one-liner beside the surviving `logger.exception`), `import: summary … rss_mb=`; prefixes byte-identical.
- `GET /api/sync/status`: additive `rss_mb`/`rss_peak_mb` (`int|null`), keyed off the ONE `_sample_rss` (run start, phase transitions, forced terminals, 5 s-throttled hook), `peak >= current` invariant, anonymous 403.
- `sources.js` `fmtSyncPeakClause`: ` · peak <N> MB` trailing the counts line / "Sync cancelled", nothing when null, no new control/live region.

Gates (exact commands)
- `uv run pytest --cov=app --cov-report=term-missing` → **4570 passed**, TOTAL **99%**, `app/api/sync.py` **100%**, `app/core/memory.py` **100%**
- `uv run ruff check .` → clean · `uv run pyright` → **0 errors**
- `uv run pytest tests/e2e/test_sync_peak_memory_visible.py -v --no-cov` → **5 passed in isolation** (ran twice)
- All 27 touched E2E families re-run **in isolation**, all green (progress_box 8, cancel 3, status_freshness 4, summary_visibility 3, sync_button 3, session_reset 4, git_freeze 2, git_log_stream_dates 5, PDF/image suites, …)

Completion criteria: every checkbox ✅ except the commit + phase-dir move, which belong to the harness.

Documentation
- README reviewed in full (pages, commands, config tables cross-checked against `app/config.py` — 85 env rows, all defaults match; phase-187 ops section, greps, process-vs-cgroup caveat): consistent, no changes needed.
- `AGENTS.md`: **fixed one pre-existing inconsistency** — rule 6 claimed the no-CDN test covers "the index page"; it actually parametrizes 10 pages (all but `/doc-edit.html`).

Notable
- Two failures early in the pass were self-inflicted by running the E2E module concurrently with the full suite on the shared Postgres (TRUNCATE deadlock + one order-dependent `test_overview` flake); both vanish under the documented serial isolation — no code defect, no change made.
- **PLAN §9 still needs the owner's reconciliation** (phase 187 adds the sync memory fields + two status keys; PLAN is never agent-edited — AGENTS rule 10 carries the spec). `TODO.md` holds an unrelated owner note, left untouched.

Next pending phase: `188_chunks_hnsw_index`.

tests/e2e/test_sync_cancel.py

@@ -93,6 +93,7 @@ from e2e.conftest import (
     USE_REAL_LLM,
     _wait_http,
 )
+from e2e.sync_helpers import PEAK_CLAUSE, counts_line
 
 REPO = Path(__file__).resolve().parents[2]
 
@@ -135,8 +136,9 @@ SYNCED_LABEL = re.compile(r"Synced \d{1,2}:\d{2}")
 
 #: The settled SUCCESS result line — "N added" or "N added · M
 #: unchanged" (sources.js's fmtSyncResult — updated/pruned are zero on
-#: the re-sync: the repo is unchanged and nothing was pruned).
-RESULT_LINE = re.compile(r"^(\d+) added(?: · (\d+) unchanged)?$")
+#: the re-sync: the repo is unchanged and nothing was pruned) with the
+#: phase-187 peak clause optional at the end (null pair → no clause).
+RESULT_LINE = re.compile(rf"^(\d+) added(?: · (\d+) unchanged)?{PEAK_CLAUSE}$")
 
 #: Settle budgets: the cancel terminal lands ~1 s after the click and
 #: the UI's 2 s poll settles at most one tick after the terminal
@@ -547,7 +549,7 @@ def test_admin_cancel_lifecycle(page: Page, app_url: str, db_ready: None) -> Non
     # Phase 150: the neutral result line rides the box (the sole sync
     # text surface — the retired announcer span is gone).
     expect(page.locator("#sync-progress-text")).to_have_text(
-        "Sync cancelled", timeout=SYNC_SETTLE_TIMEOUT_MS
+        counts_line("Sync cancelled"), timeout=SYNC_SETTLE_TIMEOUT_MS
     )
     # A1: the cancel is never rendered as a failure — no error banner,
     # no error modal in the DOM.