# Principle Migrate Callers Then Delete Legacy Apis

> Apply when introducing a new internal API while old callers still exist.

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.

- Page: https://ss33.ai/skills/michael-denyer/principle-migrate-callers-then-delete-legacy-apis-33898200162
- Publisher: michael-denyer
- Category: [Software Development](https://ss33.ai/skills/category/software-development-t44z8z) › [APIs & backend](https://ss33.ai/skills/category/software-development-t44z8z/apis-and-backend-t0x840)
- License: MIT
- Source: https://github.com/michael-denyer/pstack-claude/blob/3cff27a2dda8ab0390e3db55f4190539c5b86759/plugins/pstack/skills/principle-migrate-callers-then-delete-legacy-apis/SKILL.md

## Skill

SKILL.md: https://ss33.ai/api/v1/ss33/download/michael-denyer/principle-migrate-callers-then-delete-legacy-apis-33898200162

# Migrate Callers Then Delete Legacy APIs

- 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