Description

When an agent uses the message tool during a turn AND the turn produces an auto-reply, the sends race because they use independent code paths:

• Auto-reply → core delivery pipeline → ChannelOutboundAdapter.sendText()
• Message tool → ChannelMessageAction handler → direct channel send

Both converge on the same underlying channel send function, but with no ordering coordination. On channels with timestamp-based message ordering (Matrix, potentially others), this causes messages to appear out of order.

Steps to Reproduce

1. Configure a Matrix channel
2. Have the agent send a message via the message tool (e.g. sending media)
3. Have the agent also produce a text auto-reply in the same turn
4. Observe that the auto-reply and tool-sent message appear in unpredictable order

Expected Behavior

All outbound messages to the same room/channel should be serialized to preserve send order, regardless of whether they originate from the auto-reply path or the message tool path.

Proposed Fix

Introduce a per-room/channel send queue at the channel plugin level that both the outbound adapter and tool-action handler route through. Each send awaits the previous one, ensuring consistent ordering without artificial delays.

// Conceptual example
class ChannelSendQueue {
  private queues = new Map<string, Promise<void>>();
  
  async send(roomId: string, fn: () => Promise<Result>): Promise<Result> {
    const prev = this.queues.get(roomId) ?? Promise.resolve();
    const next = prev.then(() => fn());
    this.queues.set(roomId, next.then(() => {}));
    return next;
  }
}

This could live in the core outbound layer (benefiting all channels) or be implemented per-channel plugin.

Environment

• OpenClaw 2026.2.6
• Matrix channel plugin (@openclaw/matrix 2026.2.3)
• Matrix server: Tuwunel (Conduit fork)