What it may solve
Fork companion that auto-relinks subagent session records to the forked child: listens for the official session/created event and rewrites only the durable parentSession header frame of cold subagent children (with trash backups), so forked conversations keep their subagent panel, agent routing, and descriptors — the whole subtree follows, filtered by what the fork seed references.
Imported third-party catalog description; not a Registry verification conclusion.