pql finds the vault by walking up for a .git *directory*; a linked
worktree's .git is a *file*, so a bare `pql plan rebuild` from a fresh
worktree resolved to the MAIN checkout and left the worktree's own pql.db
empty — breaking ticket/decision reads inside worktrees (hit during the
Layer-5 batch; agents had to rebuild by hand). Pass --vault
"$(git rev-parse --show-toplevel)": the worktree root in a worktree, the
repo root on main (no-op there). Upstream pql bug filed as FR-4.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>