Proxy the background tasks of ONE of the agent’s ACP sessions live from the owning daemon, live ones first and then the daemon’s bounded settled history. sessionId is REQUIRED, unlike the workspace reads: the daemon tracks tasks per (agent, ACP session) and has no per-agent aggregate to answer with. Both the session’s own visibility rule and the agent’s apply, so a session the caller cannot see reads as absent (404) — but the session’s workspace isolation does not, because tasks are not a checkout. tracked:false means the daemon holds no tracking for that session (a runtime that reports no task lifecycle, or one that has not yet), which is data and different from an empty list; a settled task stays listed for a bounded while with its outcome. There is no cancel counterpart: no agent-protocol primitive can address a single background task, so the escape hatch is cancelling the turn. 409 when the daemon is too old to report tasks, 503 when the agent is unplaced or its daemon is offline. The control plane persists none of this.