Executing implementation plans

Uses red–green–refactor loops so behavior is pinned by tests first—ideal for new features, regressions, and refactors where you need a safety net.

Shapes REST or RPC surfaces with predictable errors, pagination, and deprecation rules before implementation locks you into brittle clients.

Coordinates subagents on slices of a larger plan—ideal when one thread would be too slow but you still need a single accountable integration point.