docs(rag): record the S1b canary pair, add packet S1d, mark S4/T4 merged

docs/branch-review-records/19c1cf380274d86de82505984d1baef6b335c14020361671fcd7b83b680aef2c.record.md

@@ -0,0 +1 @@
+| 2026-08-17 | claude/rag-d2-handover-sync | e0db503cb93ec0bc9843c91cc7b84a0e8627ea6e | docs/rag-improvement HANDOVER/COORDINATION sync after S1b canary pair + S1d packet + S4/T4 rows (docs-only) | docs-only; S1b canary root cause recorded; S1d packet added | verify:pr-local docs scope |

docs/outstanding-issues-inbox/e8a5480e-0b0e-4ab1-b7bd-6090699dd7c1.json

@@ -0,0 +1,14 @@
+{
+  "version": 2,
+  "id": "e8a5480e-0b0e-4ab1-b7bd-6090699dd7c1",
+  "createdOn": "2026-08-17",
+  "action": "add",
+  "payload": {
+    "pri": "P2",
+    "type": "task",
+    "summary": "S1d: a hedged, cited, low-confidence fast answer collapses to a citation-free provider_source_gap in the finalizer with no extractive recovery — turned the S1b canary red on summary-discharge-guidance",
+    "detail": "First post-S1b canary run 32038751592 failed one case (summary-discharge-guidance): strong_routine_retrieval; final_quality_gate:provider_source_gap, grounded false, 0 citations, citation_failure_rate 0.0227. Re-run 32039841070 and 3/3 cache-bypassed live probes took the other branch: generation_fallback:generation_quality_failed; source_backed_extractive_fallback, grounded, 4 citations. Live index unchanged (0 documents/chunks/jobs changed between runs); retrieval 36/36 identical; S1b's diff is dosing-class only. Mechanism: in src/lib/rag/rag.ts (~3580-3625) every fast-route failure shape throws into shouldRecoverFastFailureExtractively (fast + strong_routine_retrieval + results -> source-backed extractive answer), but a hedged CITED confidence:low fast answer whose lead misses providerSourceGapLeadPattern and whose body matches the broader gapLikeAnswer regex in finalizeRagAnswerQualityCore (src/lib/rag/rag-extractive-answer.ts ~3822-3845) survives the loop and is converted to a citation-free evidence_gap with NO extractive recovery. Model phrasing alone chooses the branch. Fix: give the finalizer gap conversion the same extractive recovery for fast + routine + results (or detect the broad gap in-loop); keep the citation-free terminal for genuinely empty retrieval; offline fixtures for both. Own PR, RAG impact behaviour change, canary pair, Clinical Governance Preflight. Lands BEFORE S2 (A2/A3 lengthen answers, more hedged prose). Packet: docs/rag-improvement/HANDOVER.md S1d.",
+    "source": "RAG programme coordinator, S1b canary root-cause 2026-08-17",
+    "issueUlid": "01M085NVEB2K48464KM44VGVCE"
+  }
+}

docs/rag-improvement/COORDINATION.md

@@ -67,13 +67,13 @@ their status row, and stop. They never merge, never watch CI, never dispatch can
 **Wave plan** (Track A is strictly consecutive — shared files and evidence dependencies;
 Track B is the parallel lane):
 
-| Wave | Dispatch (one fresh chat per task)                                                                | Gate to the next wave                                             |
-| ---- | ------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------- |
-| 0    | **D1** (this docs PR) + **S4** + **S1b** + **#212 T4** in parallel; **C1** post-S1 canary (done)  | D1 merged (unblocks R0); S1b merged + canary green (unblocks S1c) |
-| 1    | **R0** `issues:reconcile` (serialized) + **G1** (any time, disjoint) + **S1c** (after S1b canary) | S1c merged + canary green                                         |
-| 2    | **S2** (+S2b if split) + **S5** + **S6** (S5/S6 after S4 merges)                                  | S2 merged + canary pair + `eval:answer-quality` + Gate E          |
-| 3    | **S3** + #212 closure                                                                             | S3 merged                                                         |
-| 4    | S7+ only after explicit owner decisions (Gate B verdict, experiment appetite)                     | —                                                                 |
+| Wave | Dispatch (one fresh chat per task)                                                                                                                                        | Gate to the next wave                                             |
+| ---- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------- |
+| 0    | **D1** (this docs PR) + **S4** + **S1b** + **#212 T4** in parallel; **C1** post-S1 canary (done)                                                                          | D1 merged (unblocks R0); S1b merged + canary green (unblocks S1c) |
+| 1    | **S1c** + **S1d** + **G1** + **S5** + **S6** in parallel (disjoint files); S1c and S1d merged one at a time, each with its own canary pair (R0 reconcile landed as #2045) | S1c and S1d merged + canaries green                               |
+| 2    | **S2** (+S2b if split) + **S5** + **S6** (S5/S6 after S4 merges)                                                                                                          | S2 merged + canary pair + `eval:answer-quality` + Gate E          |
+| 3    | **S3** + #212 closure                                                                                                                                                     | S3 merged                                                         |
+| 4    | S7+ only after explicit owner decisions (Gate B verdict, experiment appetite)                                                                                             | —                                                                 |
 
 Waves 1–2 of the original plan (S1 + S4, then S2 + S5 + S6) were re-cut on 2026-08-17 after S1
 landed: the owner chose **R1 before S2** (S1's residual R1 explains most remaining lithium
@@ -174,17 +174,20 @@ Always a fresh owner ask, every single time:
 
 ## 7. Current state and next actions (update on change)
 
-- **Done:** PR #1895 (guide), PR #1899 (A1 phase 1), PR #1908 (worker handover) — merged
-  2026-08-13. **PR #2022 (S1)** merged 2026-08-17 as squash `2bd146eed`, landing verified by
-  content; canary pair baseline run 31964560921 (`8f8d111ab`) → post run 32025082010
-  (`2bd146eed`): recall 1.0/1.0, zero per-case rr regressions, answer gate 45/45. Sibling
-  `#212` T3 (PR #2023) merged as `440a34f71`.
-- **Owner decisions 2026-08-17:** R1 before S2; governance Option B.
-- **Next (Wave 0):** dispatch S4, S1b and #212 T4 as three fresh chats; merge this docs PR;
-  then R0 reconcile. G1 may start any time. Prompts: HANDOVER §7 (S1b, S1c, G1, S4) and the
-  #212 handover artifact (T4).
-- **Waiting on owner:** merges as PRs open; S1b's canary approval when it merges; later S2's
-  canary + `eval:answer-quality` + Gate E.
+- **Done (2026-08-17):** #1895, #1899, #1908 (2026-08-13); **#2022 S1** (squash `2bd146eed`);
+  **#2024 D1** (`78fe906b8`); **#2035 S1b** (merge `92f7618c0`); **#2036 S4** (`f5b093291`);
+  **#2037 #212 T4** (`1726537b7`); **#2045 R0 reconcile** (28 requests; #212 closed). Canary
+  pairs: S1 baseline 32025082010 → S1b post 32039841070, recall 1.0/1.0, zero per-case rr
+  regressions, answer gate 45/45. The first S1b post run (32038751592) was red on one non-golden
+  case; root-caused to the finalizer gap-recovery hole → packet S1d, not S1b.
+- **Owner decisions:** R1 before S2; governance Option B; S1d lands before S2.
+- **Wave 1 (dispatch now, parallel, disjoint files):** S1c (`rag-claim-support.ts`), S1d
+  (`rag-extractive-answer.ts` finalizer / `rag.ts` fast-failure block), G1 (`types.ts`,
+  `answer-stream-contract.ts`, `rag-row-contracts.ts`), S5 (harness/telemetry), S6 (`eval/docling/`).
+  Prompts: HANDOVER §7. Merge order for the RAG-behaviour ones: S1c and S1d each get their own
+  canary pair; merge one, run its canary, then the next.
+- **Wave 2:** S2 (+S2b) after S1c and S1d canaries are green. **Wave 3:** S3; S7+ owner decisions.
+- **Waiting on owner:** merges as PRs open; canary approvals for S1c, S1d, S2.
 - **Live board (artifact, owner-private):** RAG Master Plan v2 —
   `https://claude.ai/code/artifact/d5dba709-0df3-40e3-8a45-15997231533d`.