# Experiment 57J.70 — structuralActionRequired as Authoritative No-Op Contract

**Branch:** `feature/semantic-action-contract-v0.23`
**Starting HEAD:** `bd3c7d5` (fix(graph): make structural action contract authoritative)

## Objective

Answer and fix exactly:

> Can the validator emit only the authoritative `structuralActionRequired` contract diagnostic on the new-contract path, while preserving the old no-op behaviour only for legacy proposals that do not use the new field?

## Defect (from 57J.69)

When `structuralActionRequired=true` + zero-mutation proposal:

```
- structuralActionRequired is true but proposal contains no graph mutation
- answerMeaning.userSupportedMeaning is populated, but the proposal contains no graph mutation. answerMeaning alone does not constitute graph progress.
```

Both errors fired for the same proposal. Under the v0.23 design, only the first (new contract) error should fire when `structuralActionRequired` is present.

## Root Cause

The legacy semantic-only no-op guard at line 905 of `lib/graph/utils.js` used the condition:

```javascript
if (!hasMeaningfulChange && update.structuralActionRequired !== false) {
```

This meant the guard still fired when `structuralActionRequired === true`, because `true !== false`. The guard then checked `meaningPopulated` (which was true) and added a second, duplicate error message about userSupportedMeaning.

## Fix

Changed the guard condition to only fire when `structuralActionRequired` is **absent** (null/undefined):

```javascript
const fieldAbsent =
  update.structuralActionRequired === null ||
  update.structuralActionRequired === undefined;

if (!hasMeaningfulChange && fieldAbsent) {
  if (meaningPopulated) {
    // structuralActionRequired was missing while userSupportedMeaning exists.
    // Missing-field rejection already added above; skip semantic-only guard.
  } else if (!meaningPopulated) {
    errors.push("Update contains no meaningful change");
  }
}
```

This ensures:
- `true` / `false` → new contract owns no-op/mutation consistency; legacy guard is silent
- `null` / `undefined` → transition rule fires first (missing-field rejection), then legacy no-op for meaning-less proposals

## Contract Matrix After Fix

| structuralActionRequired | meaningful mutation | Result | Errors |
|---|---|---|---|
| true | absent | REJECT | 1: "structuralActionRequired is true but proposal contains no graph mutation" |
| true | present | PASS | 0 |
| false | absent | PASS (intentional no-op) | 0 |
| false | present | REJECT | 1: "structuralActionRequired is false but proposal contains meaningful mutations" |
| null/missing | populated meaning | REJECT | 1: "structuralActionRequired must be present when userSupportedMeaning is populated" |
| null/missing | no meaning + zero mutation | REJECT | 1: "Update contains no meaningful change" |

## Tests Added (structural-action-contract-v0.23 block)

1. `true + zero mutation + populated meaning` → exactly one contract error, no legacy duplicate ✓
2. `false + zero mutation + populated meaning` → pass (intentional no-op) ✓
3. `true + meaningful mutation` → pass ✓
4. `false + meaningful mutation` → exactly one contradiction error ✓
5. `null + populated meaning` → transition rule rejection preserved ✓
6. `null + no meaning + zero mutation` → legacy no-op rejection preserved ✓
7. `hasMeaningfulChange` definition unchanged (status change = meaningful) ✓
8. Schema shape unchanged (makeNode/makeEdge resolve correctly) ✓
9. Validator-level fix does not affect apply path ✓
10. Pure boolean + structural gating, no semantic keyword logic added ✓

## Tests Updated in Existing "semantic-to-mutation contract" Block

- Test 1: Changed to verify missing-field rejection fires (since `structuralActionRequired` was previously absent)
- Tests 4-8: Added `structuralActionRequired: true` where meaningful mutation is present (required by v0.23 transition rule)

## Files Changed

- `lib/graph/utils.js` — guard condition (line ~905)
- `tests/graph/utils.test.js` — updated 6 existing tests, added 10 new regression tests

## Ollama calls: 0
## Live API calls: 0
## Schema changed: NO
## Prompt changed: NO