What problem does it solve? Upgrading a Motoko canister often requires changing persistent actor state — adding fields, renaming them, or changing their types — and doing this by hand with stable variables and preupgrade/postupgrade hooks is error-prone. This Skill manages state evolution as a verified chain of migration modules that the compiler checks for consistency. ## Core Features & Use Cases - Chained migration modules: Each logical state change lives in its own timestamped file under a migrations/ directory, and the compiler verifies the whole chain composes correctly. - Field transformations: Add, rename, drop, retype, or restructure actor fields, including mapping over collections and converting Bool fields to variants. - Safe upgrade semantics: On upgrade only unapplied migrations run, fast-forwarding across skipped deployments works, and a trapping migration aborts the upgrade leaving the old version intact. - Use Case: You need to change a completed : Bool field to a status variant across thousands of stored tasks. Write one migration module that maps over the collection, run mops check --fix to verify the chain, and deploy with confidence. ## Quick Start Ask the AI to set up an enhanced migration chain for your Motoko actor by creating a migrations directory with an Init module and configuring mops.toml.
