Summary

• Removes the guard that blocked mode="session" when thread=true was not set in both sessions_spawn (subagent) and ACP spawn paths
• Enables headless persistent sub-agent sessions on all channels (Telegram, Slack, WhatsApp, Signal, etc.), not just Discord
• Thread binding remains optional — when thread=true is passed, it still attempts platform thread binding as before

Problem

sessions_spawn with mode: "session" was hardcoded to require thread: true. Since thread binding currently only works on Discord (via subagent_spawning hooks), persistent sub-agent sessions were completely unavailable on all other channels. This blocked the orchestrator pattern (main → orchestrator → workers) documented in the official docs from working on non-Discord channels.

Fix

The guard clause if (spawnMode === "session" && !requestThreadBinding) is removed from both subagent-spawn.ts and acp-spawn.ts. Session persistence and thread binding are independent concepts:

1. Session persistence (mode: "session") — session stays alive to receive announces and sessions_send
2. Thread binding (thread: true) — routes platform thread I/O to the session (Discord/Slack feature)

The rest of the code already handles the thread=false case correctly — thread binding is only attempted if (requestThreadBinding) at line 449.

Fixes openclaw#23414

Test plan

• Updated existing test to verify mode="session" without thread=true proceeds without error
• All 9 spawn hooks tests pass
• Manual: spawn sub-agent with mode: "session" on Telegram — should succeed
• Manual: spawn sub-agent with mode: "session", thread: true on Discord — should still work as before

🤖 Generated with Claude Code