Refactoring Large Code Units

Improve cohesion and readability rather than optimizing for an arbitrary line count.

Workflow

1. Read the whole unit and its important callers or tests.
2. Identify the concrete source of difficulty: mixed responsibilities, deep nesting, hidden state transitions, repeated setup, or an unstable boundary.
3. Choose extractions that have meaningful names and inputs. Follow existing repository structure rather than introducing layers solely to make units shorter.
4. Preserve behavior and public contracts unless the task explicitly changes them.
5. Verify with focused tests and the repository's normal quality gates.

A long linear function may be clearer than many tiny helpers; a short function may still combine unrelated responsibilities. Use size as a prompt to inspect, not a pass/fail threshold.

Keep the refactor scoped to what improves the current change. If a larger architectural split is justified, explain the trade-off and seek agreement before expanding scope.