v2.21.0

Added

• clean-specs skill (command-only, /clean-specs) — a post-merge net that removes spec files whose work is fully shipped: every task box checked and a title/branch-matched, un-reverted merge commit that is an ancestor of the base branch. Conservative by design — it leans toward keeping a spec on any ambiguity, reports and asks for confirmation before deleting, re-checks eligibility against fresh state, and ships the removal as a reviewable PR.

Changed

• pull-requests now removes the implemented spec as a detect-and-verify step, not a from-memory delete. It finds the branch's spec from the diff against the base, removes it, and verifies no unrelated spec was swept in by a broad git add -A — closing the path by which implemented specs reached the base branch. Unrelated specs that were swept in are restored without discarding local content.
• implement-spec cleanup defers spec removal to that step instead of hand-deleting, and points at /clean-specs as the post-merge backstop.
• clarify, write-spec, and implement-spec now delegate multi-file research sweeps to a read-only research subagent, keeping the main working context small on research-heavy flows.

Full Changelog: 2.20.0...2.21.0