Fresh --base — Stop Dispatching Against Stale main

Broader goal

Multi-step plans dispatch many jobs with --base main. Operators were hand-guarding stale bases; intermittent BLOCKED statuses looked like implementer failure.

What shipped

--base main (and other bare branch names) now fetch origin/<branch> and anchor the worktree on the remote tip when available. Local-only refs remain a fallback with a warning. Resolved SHA is logged before worktree create. Tests cover stale local main vs advanced origin.

Related

Epic plan for job-status/cost truth + GH-write identity: docs/superpowers/plans/2026-08-09-job-truth-and-gh-write-epics.md

New goalpost

Hand --base main after fetch is no longer required for correctness; epic A/B still needed for status/cost/GH identity.