## TL;DR

Healing masks regressions when edits change what is verified. Prevent it with assertion-change review gates, mutation spot-checks, and monitoring for assertion churn.

## Error

```text
(Not an error; a systemic risk. The failure mode: the suite is green and the product is broken.)
```

## Steps

1. Gate assertion changes: any edit touching an assertion needs human review. Expected: the highest-risk edits are watched.
2. Run mutation spot-checks on healed tests weekly. Expected: weak healings caught.
3. Monitor assertion churn: alert when one area's assertions change often. Expected: churn signals either flaky product or sloppy healing.
4. Keep a healing log: what changed, why, and the evidence. Expected: auditability.
5. Periodically re-verify: re-break old bugs and confirm tests catch them. Expected: the suite proven, not assumed.

## When to use

- Running agent healing continuously.
- You need systemic safeguards.

## When not to use

- One-off healing (verify that test directly).
- Human-only workflows (lighter process suffices).

## Tool compatibility

- Any framework; the controls are process plus tooling.

## Variant phrasings

### Test healing safety

The general concern; gates and monitoring.

### Automated repair regression risk

The research framing; the controls are the answer.

## Why it happens

Healing optimizes for green. Without counter-pressure, green drifts away from correct, and regressions hide behind passing tests.

## Edge cases

- The review gate must be fast or it becomes the bottleneck; time-box it.
- Mutation testing is the strongest check; budget for it on healed areas.
- A healing log doubles as training data for better healing.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_TF0Ur_nchqwpSYlvEHEe9w