Disciplined, architect-grade workflow for implementing, fixing, or refactoring code in an existing codebase. Use this skill for ANY task that will change source code — new features, bug fixes, refactors, integrations, migrations, performance work, or "just a small change" — and especially when the user says something is broken, duplicated, patched-over, inconsistent, or not wired together properly. It forces the agent to read the real code before writing any, trace the root cause instead of patching symptoms, reuse what already exists instead of adding near-duplicate code, and verify the change end to end. Use it even when the fix looks obvious.
