Communication Bridge (C4)

Central message hub - ALL communication with Claude goes through C4.

Architecture

Web Console ──┐
Telegram    ───┼──► C4 Bridge ◄──► Claude
Lark        ───┘

Components

Sending Messages

# Send to Telegram DM
cat <<'EOF' | node ~/zylos/.claude/skills/comm-bridge/scripts/c4-send.js telegram 8101553026
Hello! Quotes, $vars, **markdown** — all safe via stdin.
EOF

# Send to Lark group thread
cat <<'EOF' | node ~/zylos/.claude/skills/comm-bridge/scripts/c4-send.js lark "chat_xxx|type:group|root:msg_yyy"
Report ready.
EOF

Always pipe messages via stdin heredoc — never pass as CLI arguments. See c4-send for full reference. Treat the heredoc wrapper as fixed shell syntax: only the message body goes between the start line and the closing terminator line, and the terminator itself must never be copied into the actual outgoing message.

Database

SQLite at ~/zylos/comm-bridge/c4.db:

• conversations: All messages (in/out) with priority, status, retry tracking
• checkpoints: Recovery points with conversation id ranges
• control_queue: System control messages (heartbeat, maintenance) with priority, ack deadlines, and status lifecycle

Health & Status

The activity monitor writes ~/zylos/activity-monitor/agent-status.json which includes a health field:

Fail-open semantics: If the status file is missing or malformed, health is assumed ok — intake is never blocked by a read failure.

When health is not ok, c4-receive.js rejects incoming messages and records the channel/endpoint in ~/zylos/activity-monitor/pending-channels.jsonl. Once health returns to ok, the activity monitor sends recovery notifications to all pending channels.

Keystroke Delivery

The dispatcher supports [KEYSTROKE] control messages for sending raw keystrokes to the tmux session. This is an ops-level capability — no source gating is applied.

When a control message content starts with [KEYSTROKE], the dispatcher:

• Extracts the key name (e.g., Enter, Tab, Escape)
• Sends it directly via tmux send-keys (no buffer paste, no "Meanwhile" prefix, no verification)
• Auto-acks the control immediately after delivery

Example: the permission auto-approve hook enqueues [KEYSTROKE]Enter at priority 0 with bypass-state to auto-confirm Claude Code's permission prompts.

Any process with access to c4-control.js can enqueue keystroke controls. This mirrors the existing reality that any process can call tmux send-keys directly — the C4 queue adds priority ordering and delivery guarantees, not access control.

Service Management

pm2 status c4-dispatcher
pm2 logs c4-dispatcher
pm2 restart c4-dispatcher