principle-idempotent-rerunslisted

# Idempotent Re-runs A re-run converges on the same end state instead of failing or duplicating. Already-done is done, not an error; match before create; re-read before write. **Why:** Interruption is normal — a rate limit, a crash, a compaction, a user stop. When a failure mid-plan stops the run, the recovery story is "run it again", and that only works if the second pass is safe against the first pass's partial results. **Pattern:** - Deleting the already-deleted, closing the already-closed: report it as done and continue. Never treat convergence as failure. - Match by title or content before creating, so a re-run of an approved plan never duplicates an issue, a comment, or a construct. - Re-read each item immediately before writing it. An item whose state changed since the plan is skipped and reported, not overwritten. - Record landed steps as you go, so a re-run knows which steps remain rather than re-deriving them from hope. - Run mutations serially with backoff where a rate limit could shred a half-applied plan.