ab-reconcile

name	ab-reconcile
description	Resolve a conflicted PR by merging base into the build branch. Invoked by the build-runner as the reconcile phase; takes only the build slug.
disable-model-invocation	true

/ab-reconcile

The build's PR no longer merges cleanly: main moved. Your job is one merge commit — base merged into the build branch — that preserves both what this build was for and what landed on main since. Never rebase (SPEC §15.7: rebase re-resolves conflicts against a moving target and severs recorded SHA provenance; it is banned in this system).

Session shape

1. Run ab context. You get .ab/spec.md, .ab/plan.md, .ab/implement-notes.md, and the conflict info (baseSha in .ab/context.json). Kernel plumbing fetched the PR's configured base and resolved this SHA immediately before your session, so the commit already exists locally; it is not the older conflict-detection snapshot.

2. git merge <baseSha> in the workspace and resolve every conflict with the explicit charge to regress against neither side:

   • The spec and plan tell you what this branch's changes are for — a resolution that quietly drops the behavior they describe is a failed reconcile, even if it compiles.
   • The incoming base commits are already merged reality — a resolution that undoes them will break main.

3. Textual conflicts with one faithful resolution: resolve them. Then run the repo's checks (typecheck, tests) — a merge that compiles but fails tests is not resolved.

4. Write .ab/reconcile-notes.md — each conflicted file, what collided, how you resolved it and why that preserves both sides — then:

   ab done --notes .ab/reconcile-notes.md
   

   ab done requires the merge commit to exist and the worktree to be clean; the push is plumbing. Verification re-runs in full afterward because reconciliation changed code — that is expected, not a failure.

When not to resolve

A semantic conflict — both sides changed the same behavior's meaning, the resolution needs a decision the spec doesn't make, or preserving both sides is impossible — escalates rather than guesses:

ab escalate "main's abc123 changed the session-token format; this build's rate limiter keys on the old format. Adopt the new format (touches spec criterion 3) or key differently?" --refs src/auth.ts

A wrong guess here lands directly on main. Exactly one terminal command: ab done or ab escalate.