Implement Plan

Carry the accepted plan through its slices, one at a time. A slice is done when its outcome has been demonstrated on the real system and reviewed — not when its checks turn green.

Preconditions and Authority

• Start from an accepted plan with slices. A clear, low-risk request can carry a brief inline plan with a single slice; use /plan-it when the Why, the approach, or the slices are unresolved.
• Necessary in-scope source and test changes do not need per-file approval. Get specific approval before Git actions the plan did not authorize, destructive actions, or writes to shared or production systems, and before work outside the accepted scope or a new design decision.
• Preserve unrelated user work. Adapt details when new evidence preserves the accepted outcome and boundaries; stop for a decision when evidence invalidates a load-bearing choice.

The Slice Loop

Run every slice through these steps in order. A failing step sends the slice back to implementation; do not advance past it.

1. Red. When TDD: yes, follow /tdd, working outside-in: the first failing test sits at the level of the slice's Acceptance (an integration test against the real route, the CLI invoked end to end, an e2e flow) wherever the test environment can reach it; narrower tests follow as the implementation needs them. Test judgment decides when a slice is owed no new test; record that exemption instead of manufacturing one. For a bug, reproduce the failure first — a fix without a reproduction is a guess.