phase: 113_source_chip_quality

All gates green — no defects found; this pass was verification only.

**Phase 113 final verification pass — report**

- Verified (no code changes needed): `select_documents_tiered` cited/related tiering + `select_documents` wrapper, `TurnPlan.related_docs`, `ChatDoneEvent.related` (additive, old payloads parse), `appendRelated` UI row (`.related-doc`, never `.source-chip`), done-frame + restore-path wiring, two settings with validators, `.env.example` entries
- `uv run pytest --cov=app --cov-report=term-missing` → 2422 passed, app/ coverage **99%** (>90% gate)
- `uv run pytest tests/e2e/test_source_chip_quality.py -v --no-cov` (isolated) → 2 passed
- Regression E2E `test_retrieval_quality.py` + `test_honest_deflection.py` + `test_chat_rag.py` + `test_sources_midstream_bug.py` → 17 passed
- `uv run ruff check . && uv run pyright` → clean (0 errors); `bash .agents/validate.sh` → "validation OK"

Completion criteria:
1. Single-doc question → exactly one `.source-chip` (E2E): ✅ passed
2. Weak 2nd doc only in de-emphasized related row, never `.source-chip` (unit + E2E): ✅ passed
3. Deflected turn → zero citation chips, weak hits in related row: ✅ passed
4. Full suite green, coverage >90%, isolated E2E green, lint/types clean: ✅ passed
5. `--no-gpg-sign` commit + phase dir move: left to harness per pass rules (task files already in `complete/`)

No deviations. Next pending phase: `114_embed_question_length`.

tests/e2e/conftest.py

@@ -98,6 +98,21 @@ def app_server(mock_llm: int) -> Iterator[str]:
     # The production default stays 0.62 (re-tuned against the real
     # `embed` model's 0.41–0.84 cosine range, PLAN A8).
     env["BOR_RELEVANCE_THRESHOLD"] = "0.30"
+    # Phase 112 (defect fix): the code-default lexical_support_floor (0.35)
+    # violates the startup validator against the mock-calibrated threshold
+    # (0.30) and the app under test refused to boot — pin the
+    # mock-calibrated value (tests/conftest.py pattern). It also pins the
+    # gate quadrant end-to-end: "Who composed Rhapsody in Blue?" (top
+    # ~0.124 with FTS hits) deflects while the corroborated-lexical
+    # kafkabridge question (top ~0.239) grounds.
+    env["BOR_LEXICAL_SUPPORT_FLOOR"] = "0.15"
+    # Phase 113: the source usefulness bar (citation slot), mock-calibrated
+    # (half the threshold, like the lexical floor): a doc earns a citation
+    # chip only when its best-chunk cosine clears it (e.g. the kafkabridge
+    # doc at ~0.20 clears; the rhapsody weak hits at ~0.12 or below do not
+    # and demote to the related tier). The production default stays 0.35
+    # (app/config.py, LOCKED A2).
+    env["BOR_SOURCE_USEFULNESS_FLOOR"] = "0.15"
     # Phase 67 (LLM retry): the e2e pins the retry MECHANISM with instant
     # waits (BOR_LLM_RETRY_DELAY=0 — the 5 s default is unit-pinned via
     # tests/unit/test_config.py). BOR_LLM_RETRIES is forced to the code