Firestore Migration Skill

Generate safe, idempotent migration scripts to evolve Firestore data without loss — adding fields, renaming/restructuring, transforming formats, removing deprecated fields, backfilling, or splitting and merging collections.

This file holds the rules and process. The script template and worked migrations live in the reference:

• references/examples.md — the full migration script template plus six worked examples (add field, rename, transform, backfill, remove field, conditional), CLI commands, and best practices. Start every script by copying the template from here.

Migration Principles

Every script must be: