# Principle Migrate Callers Then Delete Legacy Apis

> Move callers to the new shape and delete the old path in the same migration wave instead of carrying a compatibility layer. Use when when replacing an internal api.

- Skill: `theonlyfusioncube/principle-migrate-callers-then-delete-legacy-apis` (Agent Skill)
- Install (CLI): `npx skillmds@latest add theonlyfusioncube/principle-migrate-callers-then-delete-legacy-apis`
- Raw SKILL.md: https://api.skillmd.com/api/skills/theonlyfusioncube/principle-migrate-callers-then-delete-legacy-apis/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: TheOnlyFusionCube (https://skillmd.com/u/theonlyfusioncube)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/theonlyfusioncube/principle-migrate-callers-then-delete-legacy-apis

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# Migrate Callers Then Delete Legacy APIs

## Trigger

When replacing an internal API.

## Rule

Move callers to the new shape and delete the old path in the same migration wave instead of carrying a compatibility layer.

## Application

1. Name the concrete decision this principle changes.
2. Apply the rule to that decision, not as a decorative citation.
3. Prefer evidence from the current repository/runtime over generic preference.
4. If the principle conflicts with an explicit user constraint, keep the constraint and state the tradeoff.