A critical fix ensures parent sessions receive streaming output from spawned sub-agents via ACP relay — enabling real-time visibility into background agent work.
OpenClaw's sessions_spawn feature lets a main agent create background sub-agents for specialized tasks. For example:
// Main agent spawns a research sub-agent
sessions_spawn({
task: "Research the latest A2A spec changes",
agentId: "research-agent"
})
When using the ACP (Agent Communication Protocol) relay — particularly for remote or distributed agent setups — streaming output from these spawned sessions wasn't being relayed back to the parent session. The sub-agent would do its work, but the parent would only see the final result, not the incremental progress.
For short tasks, waiting for the final result is fine. But for longer-running sub-agent work:
The ACP relay is how OpenClaw handles communication across session boundaries and network hops. It's particularly important for enterprise deployments where agents run on different machines or in different security contexts.
PR #34310 ensures that when a sub-agent streams output, those chunks are properly forwarded through the ACP relay to the parent session. The fix is in the session spawning logic, not the relay itself — the relay was already capable of streaming, but the spawn mechanism wasn't hooking into it correctly.
This was part of a burst of session and streaming fixes on March 4:
Together, these fixes suggest the OpenClaw team is working through a systematic review of inter-session communication patterns.
For users of sessions_spawn in ACP relay environments:
For OpenClaw deployers, this is another signal that the distributed agent patterns are maturing — edge cases that only appear in production relay setups are being systematically addressed.