To Plan

Turn a source (a file or this session's discussion), and its spec if one exists, into plan.md: ordered vertical slices, each with the outcomes it must reach, the slices it waits on, and the exact interfaces it shares with its neighbours. Plan outcomes, not steps; the to-tasks skill later turns one slice at a time into tasks against live code. Write the plan; don't build it.

Stop and ask. Follow the source as given, but when something is missing, contradictory, or looks like the wrong design, tell the user and wait. Don't fill the gap with a guess.

1. Pick the source. Use the file the user names. With none, use this session's discussion: capture the plan worked out there rather than starting over. Use the spec the user or calling skill names, or spec.md in the source's project folder; plan without one when neither exists. If the source names a spec you can't find, ask for its path. Done when you know the source and whether there's a spec.