Version

OpenClaw 2026.4.11

Summary

When calling sessions_spawn with runtime:"subagent" and omitting streamTo, the transmitted request still contains streamTo:"parent", which triggers validation failure:

streamTo is only supported for runtime=acp; got runtime=subagent

This makes subagent spawns fail even with a clean payload.

Expected behavior

• For runtime:"subagent", no streamTo should be injected.
• Omitted optional fields should remain omitted unless valid for selected runtime.

Actual behavior

• streamTo:"parent" appears to be auto-applied in transmission path/tool bridge.
• Validation rejects the request because streamTo is ACP-only.

Suggested fix

• Apply runtime-conditional defaulting: if runtime === "subagent", strip/ignore streamTo entirely.