Send a message between BMAD agents using the messenger system{project-root}/_bmad/core/messenger/messenger-config.yaml{project-root}/_bmad-output/messenger/message-queue.yamlLoad messenger config from {source}Validate type is one of: handoff, review, clarify, escalate, notify, collaborateCheck required_fields for message type are present in payloadHALT with validation error messageGenerate unique message_id: "MSG-{timestamp}-{random4}"Build message object:
```yaml
message_id: "{message_id}"
type: "{type}"
from: "{from_agent}"
to: "{to_agent}" or "{to_agents}"
priority: "{priority}"
created: "{timestamp}"
status: "pending"
payload: {payload}
```
Extract parent directory path from {queue_file}Create parent directory for {queue_file} if not exists (recursive)Load existing queue from {queue_file} (or create empty if not exists)Append new message to messages arraySort messages by priority (critical first)Save updated queue to {queue_file}Return message_id and status