principle-migrate-callers-then-delete-legacy-apis from painhardcore/pstack is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
Apply when introducing a new internal API while old callers still exist. Migrate callers and delete the old API in the same wave instead of preserving compatibility layers.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Migrate Callers Then Delete Legacy APIs
When we decide a new API is the right design, migrate callers and remove the old API in the same refactor wave instead of preserving compatibility layers.
**Rule:**
- Do not keep legacy API paths alive only because internal callers still exist
- Inventory callers, migrate them, and delete the old API immediately
- Treat temporary adapters as exceptional and time-boxed, not default architecture
- Update tests to assert the new contract, and delete tests that only protect pre-refactor implementation details
**When this applies:**
- No external users depend on backward compatibility
- The project can absorb coordinated breaking changes
- The new API is part of a simplification or refactor initiative
Keeping both old and new APIs creates dual-path complexity, slows cleanup, and makes the codebase feel append-only.
The line at the top of this page pins the label git:20260827.04830a9, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
GET https://markdownregistry.com/api/v1/artifacts/art_tre3kyltofi6hlik
GET https://markdownregistry.com/api/v1/resolve?ref=painhardcore/pstack/principle-migrate-callers-then-delete-legacy-apis
GET https://markdownregistry.com/api/v1/blob/9a91f35639fabff432f1ed8b79c2a4249d53a0a4eb7019c1aa2b8855224f27ea
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