phase: 124_image_chips_and_answers

All green. Final report:

**Phase 124 final verification pass — all criteria verified, no defects found (nothing to fix)**
- Verified the implemented phase (all 7 tasks done, changes in working tree): `BOR_ANSWER_IMAGES` toggle, `show_image` tool + refusals + `holder.shown_images`, toggle-gated prompt clause, `answer_image` frame field (None-omitting serializer) + `ChatMessage` persistence, `merge_cited_docs` auto-cite bug fix, answer-figure UI (live/restore/shared/CSS), mock triggers + E2E suite. Also confirmed the bytes route → public change matches the phase-123 shared-chat precedent (task 06 design).
- `uv run pytest --cov=app --cov-report=term-missing` → **2848 passed**, TOTAL **99%** (>90% gate)
- `bash .agents/validate.sh` → **validation OK** (tests + coverage + ruff + pyright)
- `uv run ruff check . && uv run pyright` → clean, 0 errors
- `uv run pytest tests/e2e/test_answer_images.py -v --no-cov` (isolated) → **5/5 passed**
- Mock-inert spot checks: `tests/e2e/test_image_documents.py` 4/4, `tests/e2e/test_agent_document_tools.py` 4/4

**Completion criteria:** ① zero-read suggested-tier image doc chips with figure — verified (unit matrix, integration `test_zero_read_grounded_turn_auto_cites_suggested_image_doc`, E2E bug-fix flows); ② show_image → answer figure below text/above chips, second call refused, persists + restore + shared — verified (unit handler matrix, integration round-trip, E2E feature flow); ③ default-off byte-identical (3 tools, no clause, no key) — verified (unit + integration + E2E toggle-off); ④ full suite green / >90% / lint clean — verified above; ⑤ commit + phase move — harness responsibility (changes left uncommitted in working tree, no live-infrastructure changes made).

**Next pending phase:** none — `todo/` holds only this phase; the pipeline is clear once the harness moves it.

app/config.py

@@ -412,6 +412,23 @@ class Settings(BaseSettings):
     #: (the ``upload_max_mb`` pattern).
     chat_image_max_mb: int = 10
 
+    # --- Answer images (phase 124: the LLM shows a supporting image in the answer) ---
+    #: Feature toggle for the answer-image capability (phase 124,
+    #: ``BOR_ANSWER_IMAGES``; ``0``/``false`` = off — the DEFAULT,
+    #: LOCKED A2). The single knob that turns the whole feature on or
+    #: off. Gates the ANSWER side ONLY: while on, the grounded agent is
+    #: offered the ``show_image`` tool, the HIGH prompt carries its
+    #: teaching clause, and a shown doc rides the done frame's
+    #: ``answer_image`` key (and the saved record's). While off,
+    #: behavior is byte-identical everywhere — no ``show_image`` tool
+    #: offered, no prompt clause, no ``answer_image`` key in any frame
+    #: or record. INDEPENDENT of ``images``/``BOR_IMAGES`` (LOCKED A2):
+    #: that toggle indexes image documents, this one decides whether
+    #: the model may show one in an answer — ``on`` with ``images`` off
+    #: is a coherent (if image-less) state: the tool is offered, finds
+    #: no image docs, and always refuses.
+    answer_images: bool = False
+
     # --- Docs push (phase 59: save a chat answer as documentation) ---
     #: The git repo a saved chat answer is committed to (phase 59, D3):
     #: **any** remote — a URL (``https://``, ``ssh://``, ``git@``) or a