Entry point for a new session in a Builder Stack project. After a fetch of, or a new session in, the Builder Stack repo itself, opens with the Builder Stack welcome message and team picker. Asks what you're building in one or two sentences, then routes you into one of two lanes: 0 → 1 (full strategy stack — /office-hours, /strategic-one-pager, /eng-manager — before any code) or fast iteration (straight to /engineer, /qa, /pr-comments, or /release for a production-ready PR). Infers the lane when the reply already signals it; only re-asks when genuinely ambiguous. Invoke on the first turn of a fresh session, or re-invoke mid-session after a pivot.
