phase: 123_chat_image_questions

All gates green. Verification complete.

**Phase 123 — final verification pass (all 4 tasks already in `complete/`)**

- Verified the full implementation is in the working tree: `app/api/chat_images.py` (upload/serve pair), `ChatRequest.image`/`ChatMessage.image` (path-validated, omitted-when-None), toggle-off + stale-file hinted error frames, `build_user_content` multimodal build at both sites (chat.py deflected branch + `run_agent`), config-gated composer attach/preview/upload-then-send, restore + shared rendering, CSP `img-src 'self' data:` carve-out, mock-LLM capture buffer.
- `uv run pytest` → **2796 passed**, exit 0 (unit + integration).
- `uv run pytest --cov=app --cov-report=term-missing` → **TOTAL 99%** (29/4615 missed; phase-123 modules 99–100%).
- `uv run pytest tests/e2e/test_chat_image_questions.py -v --no-cov` → **5 passed** in isolation.
- `uv run ruff check . && uv run pyright` → clean (0 errors).

**Completion criteria:** (1) attach→send→multimodal text+image to the model, bubble/reload/shared all render it, saved chat stores the PATH with `"base64" not in json.dumps(stored)` — **verified** (E2E tests 1–4 + integration round-trip); (2) `BOR_IMAGES=false` — control hidden, exact hinted error frame, zero model calls / no query_log row — **verified** (E2E test 5 + integration); (3) text-only byte-identical (`content` stays a plain `str`) — **verified** (unit + integration); (4) all gates green — **verified**; (5) commit + phase move — left to the harness per pipeline rules (no `git add`/`commit` run).

No defects found; no live-infrastructure changes (repo + local dev DB only). **Next pending phase: none** — 123 is the last phase in `todo/`.

app/rag/agent.py

@@ -1393,7 +1393,7 @@ async def run_agent(
     db_factory: Callable[[], Session],
     *,
     system_prompt: str,
-    user_message: str,
+    user_message: str | list[dict[str, Any]],
     seed_docs: Sequence[Document],
     settings: Settings,
     holder: AgentHolder,
@@ -1424,6 +1424,20 @@ async def run_agent(
     unchanged. ``()`` (the default) keeps the pre-phase-74 two-message
     request byte-identical.
 
+    User message (phase 123, TODO L6): *user_message* is the current
+    turn's user content — the plain question string (every text-only
+    turn, byte-identical to pre-phase) OR the multimodal content list
+    ``[{type: "text", …}, {type: "image_url", …}]`` for a question that
+    carried an image. FLOW (pinned): the API layer
+    (``app.api.chat``) builds the content via its ``build_user_content``
+    helper and passes it HERE — ``run_agent`` builds its OWN
+    ``[system, *history, user]`` list from this value (it does NOT
+    receive the already-built ``messages``; the deflected branch is the
+    one that consumes chat.py's list directly), so a single value
+    covers both shapes and the tool rounds / recovery / retries operate
+    on it untouched. Prior turns' images are never replayed (LOCKED A7
+    — *history* is text-only by construction).
+
     Retries (phase 67, owner-locked A2): every model request goes through
     :func:`chat_stream_retried` — a failed round is retried **before** its
     first piece (same messages, ``settings.llm_retries`` restarts, a flat