healer-single-locator-noop-guard

Healer Single-Locator No-Op Guard

When updating agent/healer.ts, preserve these invariants for BROKEN_LOCATOR healing:

1. One issue maps to one locator and one PR.
2. The changed file must actually contain the locked locator before edit.
3. The final source must remove the old locator token and add the proposed token.
4. Do not open a PR for no-op or unrelated locator changes.

Required checks

• Derive a locked locator token from failure context / strict suggestion.
• Deterministically select target file when only one candidate contains that token.
• Validate final source using semantic locator mutation checks:
  • before contains old locator test id.
  • after does not contain old locator test id.
  • after contains proposed locator test id.
• Keep strict API guard: no new unsupported helper methods.
• Keep strict comment guard: no added inline comments.

Forbidden outcomes

• Opening a PR where diff does not change the locked locator.
• Opening a PR where another locator is changed instead.
• Opening a PR where description says one locator changed but code changed none.

Good example

if (sourceWithDeterministicFallback === selectedFile.source) {
  throw new Error('Healer produced no effective code change')
}

enforceStrictLocatorMutation({
  before: selectedFile.source,
  after: sourceWithDeterministicFallback,
  originalTestId,
  proposedTestId,
  targetFile: selectedFile.path,
})

Bad example

// ❌ Opens PR based on model text only
const prBody = `Original locator: ${fix.originalLocator}`
// ...without verifying locator mutation in final source