docs: record closure metadata capture

docs/current-handoff.md

@@ -242,6 +242,14 @@ Experiment 54N tested whether an interpretation disagreement can be judged for m
 - Focused fallback case also passes: when the proposal-selected target becomes known but another real unresolved unknown remains, the terminal target is discarded and the real unresolved node is selected.
 - Focused preservation run passed via `npx vitest run tests/graph/apply-proposal.test.js -t "60B.43|60B.11|replaces downstream pricing"`; live rerun still required to prove the same outcome end-to-end under live conditions.
 
+### 60B.45 closure metadata capture in canonical harness
+
+- Extended `scripts/reproduce-multi-turn-investigation.mjs` and its deterministic harness tests to expose raw accepted-update closure metadata explicitly.
+- Harness now emits/stores `finalActiveUnknownNodeId` from the final updated graph and `finalSelectedQuestion` from the final update result.
+- Explicit `null` is now preserved for both fields rather than being omitted, closing the apparatus gap that forced 60B.44 to infer closure from absence.
+- Focused validation passed via `npx vitest run tests/reproduce-multi-turn-investigation.harness.test.js` (`67/67`).
+- The exact 60B.44 live closure case can now be rerun once with direct evidence for active-target clearing and final-question clearing.
+
 ### When This Knowledge-Management Phase Is Complete
 
 Provisional criteria for review (all confirmed met by Experiment 38 cold-start test):

docs/experiment-60b45.md

@@ -0,0 +1,82 @@
+# Experiment 60B.45 — Closure metadata capture in canonical live harness
+
+**Date:** 2026-08-14
+**Branch:** `feature/closure-metadata-capture-v0.39`
+
+## Purpose
+
+Expose `activeUnknownNodeId` and `selectedQuestion` explicitly in the canonical live harness output/capture layer so the exact 60B.44 live closure case can be rerun and classified from direct evidence rather than inference.
+
+## Why this was needed
+
+60B.44 already confirmed live graph-level closure:
+
+- customer factor resolved in place
+- decision resolved in place
+- both options preserved
+- zero new unknowns
+
+But the canonical harness did not explicitly emit/store:
+
+- final `activeUnknownNodeId`
+- final `selectedQuestion`
+
+That meant null closure had to be inferred from omission instead of being evidenced directly.
+
+## Exact harness change
+
+Modified only the canonical harness layer:
+
+- `scripts/reproduce-multi-turn-investigation.mjs`
+- `tests/reproduce-multi-turn-investigation.harness.test.js`
+
+For accepted updates, the harness now explicitly exposes:
+
+- `finalActiveUnknownNodeId`
+- `finalSelectedQuestion`
+
+### Raw source of each field
+
+- `finalActiveUnknownNodeId` ← `updatedSituationGraph.activeUnknownNodeId`
+- `finalSelectedQuestion` ← `updateResult.json.selectedQuestion`
+
+If either value is actually null, the harness now prints/stores `null` explicitly rather than omitting the field.
+
+## Explicit null distinction
+
+This was the critical apparatus gap:
+
+- `null` means the production result explicitly cleared the field
+- omitted/unavailable means the harness never captured it
+
+The updated harness now preserves that distinction.
+
+## Focused deterministic tests
+
+Added focused coverage in `tests/reproduce-multi-turn-investigation.harness.test.js` for:
+
+1. explicit null `finalActiveUnknownNodeId`
+2. explicit null `finalSelectedQuestion`
+3. populated values surviving unchanged
+4. all existing harness capture/regression behaviour remaining green
+
+## Validation
+
+Command run:
+
+```bash
+npx vitest run tests/reproduce-multi-turn-investigation.harness.test.js
+```
+
+Result:
+
+- PASS — `67/67`
+
+## What is now possible
+
+The exact 60B.44 live closure case can now be rerun once and classified from direct harness evidence for:
+
+- `finalActiveUnknownNodeId: null`
+- `finalSelectedQuestion: null`
+
+without changing any production reasoning logic or production API shape.