refactor-break-compat

# Breaking refactors ## Contract | Field | Bound contract | |---|---| | Trigger | Modernizing APIs, removing compat shims, killing feature flags, rewriting a subsystem cleanly. | | Authority | Human-gated: requires explicit human invocation, previewing target and consequence before any irreversible deletion; otherwise reversible local: writes only VCS-tracked refactor targets; rollback is version control. No remote mutation. | | Side effect | Deletes compat/adapter/flag code and rewrites every caller and test wholesale; local-delete-unrecoverable. | | Done | Zero-residue grep, all callers on new contract, tests green on new behavior (exit 0). | ## Refusals - Additive refactors that keep the old path: rejected. This skill demolishes the old path. Use a regular refactor if the old path must survive. - Shipping the intermediate state (half old, half new): rejected. Finish or revert to the version-control baseline. - Widening scope beyond the demolition manifest: rejected. Do not widen scope to resolve a finding. ## Inputs - Old API surface (required): the compat shims, legacy adapters, feature flags, version gates, and backward-compatible interfaces to demolish. - New API surface (required): the target contract every caller must adopt. - Scope (optional): file or module boundaries; when omitted, the blast-radius map determines scope. ## Procedure 1. Map the blast radius. Enumerate every file, module, and caller of the old shape using `ast-grep` or `rg`. This is the demol...