phase: 155_folder_summary_voice

All verification is complete — the whole project is 100% green. Final report:

**Phase 155 final verification pass — complete.**

**Verified (all tasks 01–04 done in `complete/`):**
- Instruction nudge in `app/rag/folder_summaries.py` (forbidden openers as the pin, 4 constraints preserved, docstring cites the phase)
- `scripts/regen_folder_summaries.py` (import_docs idiom, full mode, cron-safe summary line, fail-loud boot)
- Unit pins, integration suite, mock voice update, dedicated E2E suite

**Test / lint / coverage:**
- `uv run pytest --cov=app -q` → 100% passed (exit 0, zero failures); coverage **99%** on `app/` (>90% ✓)
- `uv run pytest tests/e2e/test_folder_summary_voice.py -v --no-cov` → **3 passed** in isolation
- `uv run ruff check .` → clean; `uv run pyright` → 0 errors, 0 warnings

**Completion criteria:**
1. Marker + header prefix byte-identical — ✅ (git vs HEAD + unit pins verbatim, green)
2. Regen script full regeneration — ✅ (live smoke: exit 0, `folders=… limit=7` summary line; misconfig boot → named stderr, exit 1; `updated_at`-advance/no-prune/canned-text semantics proven by the integration suite, green)
3. Sync path untouched — ✅ (0 diffs to `app/api/sync.py` / `app/rag/importer.py`; phase-127 pins green)
4. E2E stored + rendered without forbidden openers — ✅ (3/3, exact canned-string assertions + phase-127 regression guard)
5. Full suite green, E2E isolated green, ruff + pyright clean, coverage >90% — ✅
6. Atomic commit — deferred to the harness (working tree left intact per protocol)

**Documentation:** README.md and AGENTS.md reviewed in full — verified consistent, no changes needed (README already documents the new script in the update workflow; all `.env.example` vars documented; pages table matches routes; 17 colors = 9+8; no stale mock-voice references).

**Decisions:** No live-infrastructure changes (dev-DB read + a 0-row script smoke only). The `TODO.md` working-tree edit is the owner's own, left untouched.

**Next pending phase:** `156_table_ux_polish`.

tests/e2e/mock_llm.py

@@ -19,7 +19,9 @@ Implements just enough of the aipi surface:
     of the user message (the generator puts the document list there) —
     byte-stable for a given KB (KB overview, phase 31)
   - ``FOLDER_SUMMARY_MODE`` -> the deterministic folder one-liner
-    ``Fixture folder summary for <folder>.`` — <folder> is the user
+    ``Documentation for <folder>.`` (phase 155 task 01: the new voice
+    — a natural opener naming the folder, never the forbidden
+    "This folder contains…" openers) — <folder> is the user
     message's ``Folder: …`` header line (the generator names the
     source/folder there, phase 94), so the stored row always names its
     folder and an E2E can assert on it. Checked BEFORE the
@@ -836,7 +838,7 @@ test_llm_retry.py``). The mock is single-conversation per e2e server, so
     ""`` and ``choices[0].finish_reason = "length"`` (the exact wire
     shape of the empty ``lite`` reply: the budget spent in
     ``reasoning_content``) — and every later POST returns the normal
-    ``Fixture folder summary for <folder>.`` line (the one-shot retry,
+    ``Documentation for <folder>.`` line (the one-shot retry,
     phase 96 task 01, recovers the row).
   - the label ends with ``/e2e_empty_always``: EVERY non-stream POST
     for that label answers the empty envelope (the 1 +
@@ -3337,14 +3339,16 @@ def compose_answer(body: dict[str, Any]) -> str:
     if LONG_ANSWER_TRIGGER in user.lower():
         answer = long_answer()
     elif "FOLDER_SUMMARY_MODE" in system:
-        # Folder summary (phase 94, TODO.md L4): the ``lite`` stand-in
-        # returns the deterministic one-liner
-        # ``Fixture folder summary for <folder>.`` — <folder> is the
+        # Folder summary (phase 94, voice nudge phase 155 task 01):
+        # the ``lite`` stand-in returns the deterministic one-liner
+        # ``Documentation for <folder>.`` — <folder> is the
         # user message's ``Folder: …`` header line (the generator puts
         # the canonical source/folder identity there, imported as
         # ``FOLDER_HEADER_PREFIX`` so the mock can never drift from it).
-        # The stored row therefore always names its folder — the drill-
-        # down E2E (``test_ls_tree_drilldown.py``) asserts on it.
+        # The stored row therefore always names its folder with a
+        # natural opener (never the forbidden "This folder contains…"
+        # openers — phase 155's pin) — the drill-down E2E
+        # (``test_ls_tree_drilldown.py``) asserts on it.
         # Checked BEFORE the ``SUMMARY_MODE`` branch: the folder marker
         # CONTAINS the summary marker as a substring (``FOLDER_`` +
         # ``SUMMARY_MODE``), so the summary branch would otherwise
@@ -3363,7 +3367,7 @@ def compose_answer(body: dict[str, Any]) -> str:
             if header.startswith(FOLDER_HEADER_PREFIX)
             else "(unnamed folder)"
         )
-        answer = f"Fixture folder summary for {folder}."
+        answer = f"Documentation for {folder}."
     elif "SUMMARY_MODE" in system:
         # Document summaries (phase 30): the ``lite`` stand-in returns a
         # deterministic digest — the first 24 tokens of the user message