greenfield-clean-breaks

Start by writing the uncompromised vision sentence describing the final system with no inherited constraints, then work backward to deletion waves and owner changes. Build the new path, stop importing the old path, verify with tests and typecheck, and only then delete the old code.

Build the new path first, then stop importing the old path while leaving it on disk, verify with typecheck and tests, and delete the old path last. This keeps rollback to a single import flip if verification fails.

Pause before changing durable strings, published package APIs, auth or session schemas, migration readers for on-disk user data, encryption or sync wire formats, or amending ADRs. Greenfield pressure does not authorize silent data loss or breaking published surfaces when scope is ambiguous.

Trace definitions upward through callers, exports, routes, and docs, and look for smells like fallback readers, compatibility aliases, dual writers, optional fields preserving old shapes, and helpers that hide product decisions. Count callers with ripgrep and cite files as evidence.

An asymmetric refusal is dropping a small slice of promised behavior that creates a disproportionate share of code, branching, and testing complexity. Examples include refusing rare modes, provider-specific branches, or dual readers when the user loss is small but the implementation collapse is large.