cursor-lookback-contract has been failing on main and was not in the last chunk's rerun set. It expected a lookback floor of 4001, the sample's third segment. That segment is written active and left unsealed, and 8f48058 moved startup to resume the highest active segment in place rather than sealing it. Upstream's LookbackFloor is computed over sealed segments only and, when every segment is older than the floor time, clamps to the freshest sealed segment's MinSeq. Upstream's ingest.Open likewise resumes the active segment. So the floor is segment 1's min_seq, 2001, and a clamped v1 cursor starts at seq 2001 -- both derived from upstream, then confirmed against the process. All three modes (default, wide, disabled) pass. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>