See the [background-task runtime](../../.agents/notes/implemented/architecture/2026-06-20-generic-long-running-tool-runtime.md) and [task-registry](../../.agents/notes/implemented/architecture/2026-07-26-task-registry-seam.md) decisions.
The subsystem reference — the id scheme, the owner-fenced contract, snapshots — is [docs/subsystems/tasks.md](../../docs/subsystems/tasks.md); design in the [background-task runtime](../../.agents/notes/implemented/architecture/2026-06-20-generic-long-running-tool-runtime.md) and [task-registry contract](../../.agents/notes/implemented/architecture/2026-07-26-task-registry-seam.md) Agent Notes.