phase: 183_sync_passive_delete_cascade

All gates green. Final state verified.

**Implemented / verified**
- Task 03's work was **never actually done** (its report was a stub, `tests/e2e/test_prune_cascade_cleanup.py` did not exist) → wrote it: 3 tests — 9-file local source synced from the Sources page (`9 added`), 6 files deleted upstream, re-sync (`0 added · 3 unchanged · 6 pruned`), documents vanished from the tree + `GET /api/documents/content` 404 + total 3, **0 orphan chunk rows** via the test's own SQL, survivor chunk total unchanged; partial-prune chat turn (grounded, non-deflected, `query_log` names the survivor and no pruned doc); total source removal (`DELETE /api/git-sources/{id}`) wipes every doc+chunk of the source with 0 orphans, sibling source untouched. Mock-only (`E2E_REAL_LLM=1` skipped), own port 8199, truncate before/after.
- Tasks 01/02 re-verified: `passive_deletes=True` + mapper pin, probe flipped to `EXPECTED_CHUNK_SELECTS_PER_PRUNED_DOC = 0`, `_prune`/`delete_git_source` docstrings.
- **Drift guard proven non-tautological by my own one-off run**: scratch DB (`alembic upgrade head`) → FK `confdeltype='c'`, guard PASSES, CASCADE delete leaves 0 chunks; FK recreated `ON DELETE NO ACTION` → guard FAILS verbatim and a `passive_deletes` delete raises `ForeignKeyViolation` (never silent orphans). Scratch DB dropped; shared test DB untouched (`'c'`).

**Gates**
- `uv run pytest --cov=app --cov-report=term-missing` → **4488 passed**, `app/` TOTAL **99%** (>90%)
- `uv run pytest tests/integration/test_prune_cascade_statements.py -v` → 4 passed
- `uv run pytest tests/e2e/test_prune_cascade_cleanup.py -v --no-cov` → **3 passed in isolation**; `test_source_removal_cleanup.py` 6 passed, `test_force_push_resync.py` 2 passed (both isolated)
- `uv run ruff check .` → All checks passed; `uv run pyright` → 0 errors

**Completion criteria**: passive_deletes+pin ✅ · probe post-fix ✅ · drift guard green + proven-failing variant ✅ · full suite/coverage/lint ✅ · E2E in isolation ✅ · docs consistent ✅ · commit = harness-only (per pipeline rule I ran no git write commands).

**Docs**: fixed 4 pre-existing README inconsistencies — per-module E2E ports (claim of "one pair of fixed ports" predates phase 79), debugpy `launch.json` snippet vs the shipped file (`name`/`remoteRoot`), and the page-naming wobble (navbar labels `/sources.html` **RAG**, `/git-sources.html` **Sources** — the Sync button's home is now named correctly in 4 places); added the phase-183 E2E pointer. AGENTS.md verified accurate (rule 12 matches the delete-site audit).

**Deviation**: none from the locked decisions; the E2E is a behaviour pin (byte-identical owner-visible behaviour), the statement-count probe remains the memory teeth, as phase 183 D1/A4 specify.

**Next pending phase**: `184_sync_bounded_session`.

AGENTS.md

@@ -116,6 +116,23 @@
     await; the worker thread itself runs to completion (threads are not
     interruptible) while the loop keeps serving — pinned by the same E2E
     module's cancel-during-clone test.
+12. **Never hydrate what you delete:** `Document.chunks` is
+    `passive_deletes=True` (phase 183), so deleting a document removes its
+    chunk rows **in the database** (`chunks_document_id_fkey` is
+    `ON DELETE CASCADE`, alembic 0001) and a mass prune costs
+    O(documents). The importer's prune and the source-removal endpoint both
+    rely on it. Do not remove the keyword, and do not add a delete path
+    that SELECTs `chunks` (or a `Chunk.embedding`) on its way to deleting
+    them — one hydrated 768-dim embedding is ~24.8 KiB of Python, which is
+    how the 2026-10-15 sync's 3,008-document prune reached 4 GB and locked
+    up the VM. Pinned by
+    `tests/integration/test_prune_cascade_statements.py` (statement count,
+    zero orphan chunk rows, and a live-FK drift guard that fails the suite
+    if the cascade clause ever disappears — because then
+    `passive_deletes=True` would silently orphan rows). The
+    `doc.chunks = [...]` **re-embed** path is the deliberate, documented
+    exception (collection replacement legitimately needs the loaded
+    collection; changed files only).
 
 ## Quick reference
 ```bash