pi-letscook

Shared completion workflow protocol for long-running coding tasks with canonical .agent state, one-slice execution, mandatory role dispatch, recovery, and final stop criteria. Use only after the user explicitly enters `/cook` and the main session becomes the completion workflow driver.

Ordinary-chat contract for treating `/cook` as an optional workflow mode while requiring `/cook` to synthesize a fresh primary-agent startup handoff and fail closed when that handoff is not startable.