Claude Code's isolation="worktree" forks new worktrees from origin/HEAD, not
the live local HEAD. When prior local commits (e.g. an earlier quick task in
the same session, or this task's own Step 5.6 pre-dispatch plan commit)
advance local HEAD without an intervening push, origin/HEAD stays pinned to a
stale ancestor and the executor's worktree_branch_check guard halts with a
base-mismatch fatal that can be many commits behind, not just one.
Port the worktree.base-check auto-degrade pattern already used by
execute-phase (#683/#1369) into quick.md's single-dispatch path, run
immediately before EXPECTED_BASE is captured in Step 6.
3fe9a81428