docs: experiment 57J.43 record and handoff update

docs/current-handoff.md

@@ -721,3 +721,33 @@ Provider-agnostic concern: YES — CONTRACT LEVEL
 Smallest correction boundary: Two Additional Guidance bullets (~10 words total) at lines ~132 of prompt-builder.js must be removed or conditioned on rule #6 not triggering. Text-preservation-only tests do not prove prompt coherence.
 
 Configured Ollama: none used. Production code changed: NO. Prompt changed: NO. Tests changed: NO. Dev server disturbed: NO.
+
+### Experiment 57J.43 — Remove Surviving Semantic-Only/No-Op Prompt Conflict
+
+**Objective:** Apply the smallest proven correction from 57J.42: replace two Additional Guidance bullets that conflicted with rule #6's MUST rule, plus add one clarifying bullet and seven focused tests. Bounded prompt-contract task only. Not solving update-vs-add action selection.
+
+**Production changes:**
+- `lib/graph/prompt-builder.js` — Replaced two conflicting Additional Guidance bullets (line ~131-132):
+  - Old: "If the answer does not justify a change, return empty arrays for every category." → Now conditioned on rule #6 not applying.
+  - Old: "Use answerMeaning to preserve the answer's direct meaning even when the graph change remains unresolved." → Replaced with explicit semantic-fidelity vs structural-mutation separation.
+  - Added: Edge-connection requirement for new unknown nodes (clarifying bullet, consistent with existing rule #13a).
+- `tests/graph/prompt-builder.test.js` — Added 7 focused tests covering all seven required coverage areas.
+
+**What this guarantees:**
+1. Empty-array permission is explicitly subordinate to rule #6 — MUST vs PERMIT contradiction eliminated.
+2. `answerMeaning` can no longer substitute for graph mutation per the corrected bullet text.
+3. All existing contracts preserved: duplicate avoidance, genuinely-new-concepts protection, fidelity/inference separation, traceability, update/refine preference.
+
+**What is intentionally left unresolved:**
+1. Action selection under rule #6 (update vs add) — confirmed ambiguous by 57J.42.
+2. Live production validation — requires next experiment pass.
+
+**Test results:**
+- prompt-builder.test.js: 22/22 pass (7 new + 15 pre-existing)
+- utils.test.js: 68/68 pass
+- apply-proposal.test.js: 64/64 pass
+- Total: 154 tests, 0 failures
+
+**Classification: E — IMPLEMENTATION COMPLETE (prompt correction only)**
+
+Configured Ollama: none used. Production code changed: prompt + tests only. Dev server disturbed: NO.

docs/experiment-57j43.md

@@ -0,0 +1,72 @@
+# Experiment 57J.43 — Remove Surviving Semantic-Only/No-Op Prompt Conflict
+
+**Branch:** `feature/semantic-to-mutation-contract-v0.18`
+**Starting HEAD:** `0c477adea99c8b6532cd0482fd7f1a41b6afbaee` (frozen v0.17)
+**Production commit:** `359ccc4` prompt: remove semantic-only mutation conflict
+
+## Objective
+
+Apply the smallest proven correction from 57J.42's diagnosis: replace the two conflicting Additional Guidance bullets so that no surviving instruction tells the model it may preserve semantic meaning with an empty graph mutation when rule #6's structural-mutation MUST rule applies.
+
+Not solving update-vs-add action selection (confirmed unresolved by 57J.42).
+
+## What Was Changed
+
+### Prompt (lib/graph/prompt-builder.js, Additional Guidance)
+
+**Replaced two bullets:**
+
+```
+- If the answer does not justify a change, return empty arrays for every category.
+- Use answerMeaning to preserve the answer's direct meaning even when the graph change remains unresolved.
+```
+
+**With three conditional bullets:**
+
+```
+- If rule #6 does not apply (the answer contains no user-supported meaning that requires graph progress) and there is no other justification for change, return empty arrays for every category.
+- If rule #6 applies but you choose an update/refinement of existing structure, resolve an existing unknown, or add justified new structure, your structural proposal plus answerMeaning together represent the complete response — answerMeaning preserves semantic fidelity while structural mutation handles graph progress; neither replaces the other.
+- If you add a new unknown with addedNodes, connect it with at least one addedEdge to an existing updated/resolved node or to a newly added non-unknown node from the answer.
+```
+
+### Tests (tests/graph/prompt-builder.test.js)
+
+Added 7 focused tests:
+
+| # | Test | Coverage |
+|---|------|----------|
+| 1 | no direct contradiction remains | Both MUST and empty-array permission must coexist with rule #6 as a condition on the permission |
+| 2 | legitimate true no-op preserved | Empty arrays still allowed when rule #6 does not apply |
+| 3 | answerMeaning is not structural progress | Must reference "semantic fidelity" not "graph change remains unresolved" |
+| 4 | duplicate protection preserved | Rule #4, #11 + AG preference for updates intact |
+| 5 | update/refine route preserved | update/refinement still listed as valid option in both rule #6 and Additional Guidance |
+| 6 | possibleInference separation preserved | Rule #27 untouched; Additional Guidance does not reference possibleInference for mutation trigger |
+| 7 | no action-selection machinery added | No keyword routing, node-kind decision table, or provider-specific paths introduced |
+
+## Test Results
+
+- prompt-builder.test.js: **22/22 pass** (7 new + 15 pre-existing)
+- utils.test.js: **68/68 pass** (pre-existing regression)
+- apply-proposal.test.js: **64/64 pass** (pre-existing regression)
+- Total: **154 tests, 0 failures**
+
+## What This Guarantees
+
+1. The empty-array permission in Additional Guidance is now explicitly conditioned on rule #6 not applying — eliminating the MUST vs PERMIT contradiction diagnosed in Pattern E of 57J.42.
+2. `answerMeaning` can no longer be interpreted as substituting for graph mutation, because the corrected bullet explicitly separates semantic fidelity from structural mutation.
+3. All existing contracts are preserved: duplicate avoidance, genuinely-new-concepts protection, fidelity/inference separation, traceability, update/refine preference.
+
+## What Is Intentionally Left Unresolved
+
+1. **Action selection under rule #6** — when rule #6 applies and multiple structural paths exist (update vs add), the prompt still does not provide decision criteria. This was confirmed by 57J.42 as a separate ambiguity from Pattern E.
+2. **Live production validation** — this commit only corrects the prompt text and tests; whether the corrected prompt produces compliant proposals in practice requires a live regression pass (next experiment).
+
+## Stop Conditions Met
+
+- No validators changed
+- No schema changed
+- No semantic classifiers added
+- No provider-specific logic added
+- No action-selection machinery added
+
+## Documentation Updated: YES