phase: 185_sync_defer_content_fast_path

All gates green. Report:

**Implemented / verified (phase 185)**
- `_doc_row_stmt` is the ONE deferral helper for all four fast-path row loads; only `Document.content` is deferred, no `raiseload`/`noload` (LOCKED A1/A2) — pinned by `tests/unit/test_importer_defer_content.py`.
- `tests/integration/test_import_fast_path_columns.py` (5), `tests/e2e/test_fast_path_deferred_content.py` (3, isolation) green; added 2 constraint pins to `test_import_session_retention.py` (summary-NULL backfill survives the cadence; both prune guards cost the same statement budget).
- **Fixed 6 pre-existing E2E failures** (all reproduce at HEAD with this phase's importer reverted): stale pins from phase 168 `Settings` nav link (`test_nav_rename_sources`), phase 182 `verbatim.js` script count (`test_steering`), phase 175 `/api/chats?limit=…` pagination breaking `endswith` counting (`test_navbar_refresh`), phase-167 lazy-drill race in the breadcrumb read (`test_modal_back_button`), nav-length tab budget (`test_suggestion_chips`).
- **Fixed a genuine flake** in `test_source_chip_quality` (passed/failed across identical runs): `ORDER BY embedding <=> q` is not a total order, so equal-cosine fixtures get a different RRF rank each run. Pinned it as an explicit tie-group (`_assert_ranked` / `_assert_related_pair`) instead of an exact order.

**Tests / lint (all 100% green)**
- `uv run pytest --cov=app --cov-report=term-missing` → **4519 passed**, `app/rag/importer.py` **99%**, `TOTAL` **99%** (>90%).
- `uv run ruff check .` → All checks passed; `uv run pyright` → 0 errors.
- Full E2E sweep, one pytest process per file (the README's sanctioned loop) → **167/167 files OK, 0 FAIL** (re-run after the fixes).

**Completion criteria**: helper shared by 4 loads ✅ · column-list + 1-SELECT + backfill pins ✅ · `test_importer_unchanged_fast_path.py` 24 passed, zero expectation edits ✅ · full suite + coverage + lint/types ✅ · phase E2E in isolation ✅ · docs accurate ✅ · commit left to the harness (no git commands run).

**Documentation**: README + AGENTS.md already carry the phase-185 rule; full pass found and fixed no doc inconsistencies (env vars: all 85 `Settings` fields documented in `.env.example` + README, no ghosts; every `app/… tests/… scripts/…` path referenced in both files exists).

**Deviations**: (1) the ranking non-determinism behind the chip-quality flake is real in `app/rag/retriever.py` — a SQL tie-break would cost pgvector index usage, so I kept the fix test-side; a follow-up phase should make vector-candidate ranking a total order. (2) Two tracked E2E screenshots were regenerated by the sweep (artifacts, left modified).

**Next pending phase**: `186_git_log_streaming_dates`.

tests/e2e/test_navbar_refresh.py

@@ -71,6 +71,7 @@ from collections.abc import Callable
 from pathlib import Path
 from threading import Thread
 from typing import Any
+from urllib.parse import urlsplit
 
 import httpx
 from playwright.sync_api import Locator, Page, Request, expect
@@ -510,7 +511,23 @@ def test_all_four_data_views_refetch_on_reshow(
     log = _get_logger(page)
 
     def count(endpoint: str) -> int:
-        return sum(1 for u in log if u.endswith(endpoint))
+        """Requests to ONE endpoint: exact path, plus every query pair the
+        pin names. Phase 175 paginated the History list
+        (``/api/chats?limit=25&offset=0``, ``history.js``), so the plain
+        ``endswith`` this suite used to count with stopped seeing the
+        view's own fetch altogether — the mount baseline never arrived and
+        the loop timed out on the FIRST view."""
+        path, _, query = endpoint.partition("?")
+        wanted = [pair for pair in query.split("&") if pair]
+        total = 0
+        for url in log:
+            parts = urlsplit(url)
+            if parts.path != path:
+                continue
+            params = parts.query.split("&") if parts.query else []
+            if all(pair in params for pair in wanted):
+                total += 1
+        return total
 
     for nav_sel, view_path, endpoint in DATA_VIEWS:
         # First show (the mount) — wait until the mount's own load