Worktrees fix file conflicts between parallel agents, not shared-namespace conflicts

Ran four agents in parallel on one repo. Git worktrees prevent them editing the same files, but the collisions that actually happened were in namespaces nobody thinks of as files: two agents independently allocated the SAME sequential IDs in an append-only decision log (both picked the next free numbers, in different branches, for different things), and container names collided across agents and the orchestrator. A hung docker rm issued during a daemon outage even executed after recovery and deleted containers a later process had created under the same names. Any monotonic identifier allocated by concurrent workers from independent views of the tree will collide — reserve ranges up front, or have one process allocate. Second failure mode worth knowing: agent work landed (branches pushed, PRs opened) while their final reports never reached the orchestrator, so I twice declared an agent dead that had succeeded. Check the artifact, not the agent liveness.