experiment: validate controlled structural no-op live

docs/current-handoff.md

@@ -1441,3 +1441,11 @@ New branch: `feature/semantic-action-contract-v0.23`
 **What this fixes:** The self-defeating constraint from 57J.73 where Answer 2 was unreachable because Update 1 failed at proposal_compatibility when declaring `structuralActionRequired=true` with zero mutation. Now the harness can inject a pre-anchored graph as the Update input, enabling direct testing of whether the live model produces `false + no meaningful mutation → accepted` on a graph that already contains the savings-realism anchor.
 
 **What remains unproven:** Whether the live model will actually produce `false + no meaningful mutation` for Answer 2 when given this pre-anchored graph (a separate live experiment is required).
+
+### Experiment 57J.75 — Pre-Anchored No-Op Update Live Test
+
+**Objective:** Run a single controlled live test: inject the pre-anchored savings-realism fixture directly as the Update input with an answer preserving existing uncertainty, and verify the model produces `false + zero mutation → accepted`. **Classification: A — INTENTIONAL NO-OP WORKS.**
+
+**Answer:** The one controlled run shows that with an equivalent savings-realism uncertainty already present, the model directly emitted `structuralActionRequired = false`, produced zero meaningful mutation (no added/updated nodes or edges), and the production validator accepted the proposal. All four required conditions met: structuralActionRequired=false observed directly, zero meaningful mutation, HTTP 200 / update_applied, exactly one equivalent savings-realism uncertainty remained after Update.
+
+**What remains unproven:** Whether `false + zero mutation` would also be accepted for non-anchored graphs; cold-start comparison via normal Start→Update; stability across repeated runs (only one run); generalization beyond savings-realism anchors.

docs/experiment-57j75.md

@@ -0,0 +1,101 @@
+# Experiment 57J.75 — Pre-Anchored No-Op Update Live Test
+
+**Branch:** `feature/semantic-action-contract-v0.23`
+**Starting HEAD:** `8184e05` (docs: record pre-anchored update apparatus)
+**Experiment commit:** pending (`experiment: validate controlled structural no-op live`)
+
+## Objective
+
+Answer exactly:
+
+> Given a deterministic pre-existing graph fixture with a savings-realism anchor already present, does the live model produce `structuralActionRequired = false` + zero meaningful mutation when updating with an answer that preserves the existing uncertainty, and is that accepted?
+
+This is the direct follow-up to **57J.73** (Classification G), where the `false + no meaningful mutation → accepted` branch was unreachable because Update 1 failed at `proposal_compatibility`. The apparatus from **57J.74** enables this test via a pre-anchored fixture injected directly into the Update request's `situationGraph`, bypassing Start entirely.
+
+## Hypothesis
+
+If the model receives a pre-anchored graph where the savings-realism unknown already exists, and updates with an answer that preserves (rather than resolves) that uncertainty, it will:
+1. Declare `structuralActionRequired = false` (no new structure needed)
+2. Produce zero meaningful mutation (graph unchanged)
+3. Be **accepted** (not rejected by the contract validator, because the v0.23 contract validates `false + zero mutation` as a valid intentional no-op)
+
+## Tooling
+
+The pre-anchored apparatus from **57J.74** consists of:
+1. JSON fixture: `tests/fixtures/pre-anchored-update-savings-realism.json` — deterministic graph with one unresolved savings-realism unknown
+2. Harness tests: `scripts/reproduce-multi-turn-investigation.harness.test.js` — 10 deterministic tests covering anchor count, schema validity, relationship integrity, exact graph injection
+
+The live test sends the fixture's graph directly as the Update request's `situationGraph`, with an answer that preserves (not resolves) the existing uncertainty.
+
+## Test Config
+
+- **Fixture:** Pre-existing graph with savings-realism unknown (`n_savings_realism`, kind=unknown, status=unknown)
+- **Answer:** "I am still unsure whether the projected office savings from the relocation are realistic."
+- **Model:** qwen-claude:latest at http://192.168.1.111:11434
+- **Previous Question:** "Are the projected office savings from relocation realistic?" (from fixture)
+
+## Results
+
+**HTTP status: 200 — update_applied**
+
+```json
+{
+  "success": true,
+  "stage": "update_applied",
+  "proposal": {
+    "structuralActionRequired": false,
+    "answerMeaning": {
+      "userSupportedMeaning": "The user remains unsure whether the projected office savings from relocation are realistic.",
+      "possibleInference": "Proceeding with relocation without validated savings projections carries unquantified financial risk.",
+      "supportCategory": "uncertain",
+      "resolutionGuidance": "may_resolve"
+    },
+    "addedNodes": [],
+    "updatedNodes": [],
+    "addedEdges": [],
+    "resolvedUnknownNodeIds": []
+  }
+}
+```
+
+**Graph after Update:** Unchanged — still exactly 2 nodes (1 state, 1 unknown) and 1 edge. The savings-realism anchor persisted without modification.
+
+**Next Question generated:** "What would clarify are the projected office savings from relocation realistic in this situation?"
+
+## Evidence Summary
+
+This one controlled run shows that, with an equivalent savings-realism uncertainty already present in the pre-anchored graph, the model directly emitted `structuralActionRequired = false`, produced zero meaningful mutation (no added/updated nodes or edges), and the production validator accepted the proposal.
+
+## Classification: A — INTENTIONAL NO-OP WORKS
+
+All four conditions met:
+1. `structuralActionRequired = false` observed directly in the Update response
+2. Zero meaningful mutation (addedNodes=[], updatedNodes=[], addedEdges=[])
+3. HTTP 200 / update_applied
+4. Exactly one equivalent savings-realism uncertainty remained after Update
+
+## What this establishes
+
+This controlled run demonstrates that when the model receives a pre-anchored graph with an existing savings-realism unknown and produces an answer preserving that uncertainty, it correctly declares no structural action needed and is accepted by the v0.23 contract validator. The `false + zero mutation → accepted` path does exist in the contract for pre-anchored inputs.
+
+## What this does NOT prove
+
+1. Whether `false + zero mutation` would also be accepted for non-anchored graphs (where the model might legitimately need to create structure)
+2. Whether the same answer would produce different results starting from a clean Start (i.e., whether cold-start dynamics change the outcome)
+3. Stability across repeated runs — only one test run was performed
+4. Whether this generalizes to other types of anchors beyond savings-realism
+
+## What remains unproven
+
+1. **Cold-start comparison:** Run the same answer through normal Start→Update to compare whether the starting state changes the model's structural-action judgment.
+2. **Different anchors:** Test with different pre-anchored graphs (e.g., risk-constraint anchor, timeline anchor) to verify generalization.
+
+## Production code changed: NO
+
+No production logic changed. Only deterministic harness tests from 57J.74 were used as the test apparatus.
+
+## Harness restored: YES
+
+Scenario, answers, and maxUpdates in `scripts/reproduce-multi-turn-investigation.mjs` remain at canonical defaults. No fixture mode was committed to the harness.
+
+## Dev server disturbed: NO