Contract Field Repair

2. Classify the Failure

3. Apply the Patch

• Use Edit tool with exact old_string → new_string targeting only the mismatched field name.
• Never replace the entire contract/output block.
• Never re-run the full task to regenerate output.
• If multiple fields are wrong, apply one patch per field.

4. Verify

• Re-read the patched output.
• Validate all output_contract.required fields are now present with correct names.
• Confirm no data was lost or corrupted by the patch.

Expected Inputs

• A failed contract validation result (field names expected vs actual).
• The file path containing the output block.
• The contract schema (from SKILL.md or task spec).

Expected Outputs

• mismatched_fields: List of {expected, actual, action} tuples describing each mismatch found.
• applied_patches: List of {field, old_name, new_name, file, line} for each rename applied.
• validation_result: pass or fail after patches applied.

Error Handling

• If more than 3 fields are mismatched in a single block, flag for manual review — the output may have been generated against a wrong schema version.
• If the actual output contains no semantic equivalent for a required field, escalate rather than fabricating data.
• If the output file cannot be read or parsed, fall back to the standard task-execution retry flow.

Anti-Patterns (Do NOT)

• Do NOT regenerate the full output block to fix a single field name.
• Do NOT re-execute the entire task when only the contract envelope is wrong.
• Do NOT silently drop fields that don't match — every field must be accounted for.
• Do NOT guess field mappings without checking semantic equivalence first.

Origin

Captured from pattern observed in shift_20260331_16_evening_wrap__retry1: agent diagnosed a files_modified vs files_changed mismatch and applied a single targeted rename, avoiding full-block regeneration. This saved tokens, preserved correct data, and reduced retry latency.