wit-breaking-change-check

Run a git diff of the wit/ directory against the base branch, then classify each modification against the breaking-change taxonomy in wit/VERSIONING.md. Removing or renaming types, functions, fields, or cases is breaking, while new types, interfaces, and worlds are non-breaking.

Breaking changes include removing or renaming any type, function, record field, enum case, or variant case, adding a case to an existing enum or variant, changing function signatures or field types, reordering record fields, and adding required fields or non-capability-gated required functions.

Non-breaking changes include new flags bits, new capability-gated functions, new record, variant, or enum types, new interfaces, new worlds, and adding @since or @unstable annotations. Adding cases to an existing enum or variant is still breaking.

The .frozen marker signals that a wit/vN/ version is stable and subject to the breaking-change compatibility window. Without it, the version is experimental and components must simply be rebuilt against the WIT shipped by the target host.

Run it before merging any branch that touches the wit/ directory, when reviewing PRs that modify WIT interface definitions, and before publishing a plugin-compatible release to verify changes are safe.