# Self-Modification Diff Gate

> Every self-edit the agent proposes goes through a separate critic persona before it lands — safety constraints can't be quietly removed and bad edits stay auditable.

- **Category**: Agentic AI
- **Subcategory**: Verification & Reflection
- **Canonical URL**: https://designpattern.fyi/patterns/inner_critic/

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## Description
**Intent**: Make recursive self-improvement survivable by gating every self-edit through an independent critic.

**Context**: Your agent edits its own source code, system prompt, or rule files as part of normal operation. A bad edit can leave it broken or — worse — superficially working with safety constraints silently removed.

**Solution**: Every self-edit goes through a critic step: a separate prompt (optionally a separate model) reviews the proposed diff against criteria (safety, charter compliance, tests passing). Edits land only on critic approval. Rejected edits are logged for human review. The critic runs on a frozen checkpoint so a malformed self-edit can't corrupt the critic before it votes. Recursion guard required when the critic itself is in the edit scope.


## Use Cases
- The agent edits its own code, prompts, or rules and bad edits would be hard to reverse.
- A separate critic prompt or model can review proposed diffs against explicit criteria.
- The critic can run on a frozen checkpoint, isolated from the edit scope.





## Trade-offs


### Advantages

- Recursive self-improvement becomes survivable — bad edits don't auto-land.

- Audit trail of what was rejected is itself learning signal.




### Considerations & Drawbacks

- Critic prompt is load-bearing; a bad critic is worse than no critic.

- Two-step pipeline doubles per-edit latency.







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**Reference**: [Original Source](https://www.agentpatternscatalog.org/patterns/self-modification-diff-gate/)