Agent Mailbox

The agent mailbox is the receipt-backed coordination channel for one agent role to ask another agent role for review, status, decisions, or handoff context.

CLI

craik agent-message send \
  --task-id task_123 \
  --from-agent agent:orchestrator \
  --to-agent agent:verifier \
  --subject "Review patch" \
  --body "Please verify the changed files." \
  --run-id run_123 \
  --from-role-id role_orchestrator \
  --from-role-kind orchestrator

craik agent-message receive agent_message_123 --received-by agent:verifier

send requires --run-id. Craik loads the run and verifies that the requested --from-agent, --from-role-id, and --from-role-kind match the sender run before persisting the message. The sender string is not trusted on its own.

Receipts

Mailbox sends create agent.message.send receipts. Receives create agent.message.receive receipts. Message IDs are stable for the first message with a subject and receive numeric suffixes for repeated same-subject messages so history is not silently overwritten.

Prompt Boundary

Mailbox bodies are untrusted peer-agent content. Downstream prompts must treat them as evidence to inspect, not instructions to obey.