feat(rag): honest deflection gate with amber UI state and alternative-question chips

README.md

@@ -210,9 +210,23 @@ served locally (no CDN), `BOR_ENVIRONMENT=production`.
   `uv run python -m scripts.llm_probe`, update `BOR_EMBEDDING_DIM`, then
   drop + recreate the chunks table (new migration or manual `TRUNCATE
   chunks, documents`).
+- **Honest deflection (the amber “I haven't done anything like that”
+  bubble)** — every question passes the honesty gate: when the best
+  cosine similarity is below `BOR_RELEVANCE_THRESHOLD` (default `0.30`),
+  Brain switches to deflection mode instead of guessing. The LLM prompt
+  then carries weak-hit *titles only* (no document content), the reply
+  opens with “I haven't done anything like that”, the bubble renders
+  amber with “Maybe try” chips derived from the closest indexed titles,
+  the SSE `done` event carries `deflected: true` + `suggestions[]`, and
+  the `query_log` row records `deflected=true` + the weak `top_score`.
+  This is a feature, not a bug — the KB simply has no notes that close;
+  the chips always point at topics Brain really covers.
 - **Answers deflect too often / too rarely** — tune
   `BOR_RELEVANCE_THRESHOLD` (lower = answers more, higher = more honest
-  deflection). Check `query_log` for the actual scores:
+  deflection): `0.0` ⇒ every question gets answered, even unknown topics
+  (expect confident-sounding guesses); `1.0` ⇒ everything deflects
+  (nothing but a perfect 1.0 score counts as relevant). After changing
+  it, check the real scores:
   `psql … -c 'SELECT question, top_score, deflected FROM query_log ORDER BY created_at DESC LIMIT 20'`
 - **KB offline banner in the chat** — Postgres isn't running:
   `podman compose up -d db`.