Description

Every inbox message is delivered exactly twice to the receiving terminal. This corrupts
agent input streams in multi-agent workflows using assign + send_message.

Root Cause

In inbox_service.py, check_and_send_pending_messages() calls send_input() before
update_message_status(DELIVERED). The send_input() types into tmux, which updates the
terminal log file, which triggers the watchdog's on_modified handler. The second watchdog
invocation calls get_pending_messages() and finds the message still PENDING (because
update_message_status hasn't committed yet), so it delivers the message again.

Reproducer

1. Create a session with a supervisor agent
2. Use assign to create a worker agent
3. Worker calls send_message back to supervisor
4. Observe the message appears twice in the supervisor's tmux window

Fix

Move update_message_status(message.id, MessageStatus.DELIVERED) before
terminal_service.send_input(). PR: #

Environment

• CAO version: 2.0.0 (commit d2e9b56)
• OS: macOS
• Provider: kiro_cli

File the issue first, then reference it in the PR. Want me to help with anything else on this?