Change Amplification

---
name: change-amplification
description: "Find PR change-amplification from missing owners/contracts; rank cleanup backlog."
disable-model-invocation: true
---

# Change Amplification

Find PRs showing change amplification: one intended change forced edits across multiple conceptually separate places because architecture lacked one clear owner, contract, or boundary.

Not a blame report or list of bad PRs. Output = ranked backlog of missing boundaries with PR links as evidence.

## Inputs

Use PR history, current code, repo docs/tests. Prefer `gh` for PR data.

```bash
gh pr list --state merged --limit 100 --json number,title,url,body,mergedAt,files,additions,deletions
gh pr view <pr> --json number,title,url,body,files,commits,mergedAt
gh pr diff <pr> --patch
```

If target window, repo, or PR set unclear, ask or choose bounded recent window and say so.

## Candidate Detection

Look for PRs where:
- one intended conceptual change appears in title/body,
- edits span conceptually separate layers or artifacts: source, tests, config, prompts, docs, generated code, scripts, migrations,
- repeated edits look like drift from a missing owner/contract/boundary,
- same invariant encoded in multiple places,
- tests had to change in many areas because no single contract captured behavior.

Reject PRs where breadth was justified:
- genuine cross-cutting feature,
- intentional broad refactor,
- generated/mechanical update only,
- migration that necessarily touches all call sites,
- formatting/rename-only breadth,
- one-time cleanup with no future leverage.

## Verification Against Current Code

Before reporting candidate as actionable, verify suspected boundary gap still exists in current code.

1. Inspect current files that carried the amplified change.
2. Search for current owner/contract/type/test/lint rule that may already centralize the concept.
3. If current code fixed the issue, mark `Resolved` or omit from actionable backlog.
4. If evidence incomplete, mark `Needs investigation`, not actionable.
5. Include only actionable cleanups when current code still shows duplicated ownership, scattered invariant logic, weak contract, or missing guardrail.

## Analysis Questions

For each verified candidate:

1. Intended change: single conceptual change, usually from PR title/body.
2. Amplification evidence: which files/tests/configs/prompts/docs had to change. Cite paths.
3. Why architectural: why this wasn't ordinary feature breadth. Name missing boundary, owner, or contract.
4. Better architecture: smallest change making next similar PR local.
5. Mechanical prevention: what test, type, lint, schema, or contract check catches drift next time.
6. Deletion criterion: what temporary compatibility path should be removed once new owner exists.

## Ranking

Rank by expected future leverage:
1. Frequency likely to recur.
2. Number of concepts/files made local by the fix.
3. Bug risk from duplicated invariants.
4. Simplicity of cleanup.
5. Existence of clear mechanical prevention check.

Do not over-rank speculative architecture rewrites. Prefer small owner/contract moves with obvious payoff.

## Output

```markdown
## Ranked Change-Amplification Backlog

### 1. <missing boundary / owner / contract>
- PR evidence: <PR title> <PR link>
- Intended change: <single conceptual change>
- Amplification evidence: <paths grouped by concept>
- Current-code validation: <what was checked; why issue still exists>
- Why architectural: <missing owner/contract/boundary>
- Better architecture: <smallest localizing change>
- Mechanical prevention: <test/type/lint/contract check>
- Deletion criterion: <compat path to remove later>
- Leverage: High | Medium | Low — <why>

## Rejected Candidates
- <PR link/title>: rejected because <genuine cross-cutting/refactor/resolved/etc.>

## Verification Notes
- Commands/data sources used.
- Limits or blind spots.
```

Findings evidence-backed. No private transcript paths, secrets, or unrelated personal data.