Build a Feature, Phase by Phase

One phase, one PR, reviewed and fixed in rounds before merge. A feature built in one branch can't be tried; code merged after one review pass merges its fixes unreviewed.

main
 └─ integrate/<plan>                         cut once, before the first phase
     ├─ <plan>-phase-1 ──PR──▶ integrate     build, verify, review x2-3, fix, merge
     ├─ <plan>-phase-2 ──PR──▶ integrate
     ├─ <plan>-phase-N ──PR──▶ integrate
     └──────────────────PR──▶ main           demo, then the user merges

one phase: feat/<plan> ──PR──▶ main          no integrate branch

Start from the plan file, never memory. Path from the argument, else look under plans/ and ask if several match. Re-read it each phase. Any _open_ decision: stop, send the user back to planning. Read every Verify line and ## Demo before phase 1 — a phase with no proof and no deferral is a planning bug, cheapest to raise now.

One integration branch per feature; one branch and one PR per phase. Cut integrate/<plan-name> from up-to-date main and push it, reusing it if it exists. Every phase branches from it and targets it, so main never holds half a feature. Build the first phase with unchecked boxes. Never pull work forward from a later phase, even three lines — the boundary is what makes the PR reviewable. One-phase plan: no integrate branch — branch off main as feat/<plan-name>, target main, and after the demo stop at the green PR for the user to merge, no final PR after it.