Tmux Sender

tmux Command Sending Skill

This skill provides command sending and monitoring capabilities between tmux panes.

Execution Contract

This skill follows the non-entry execution contract standard. Required contract_extensions: pane_target, command_count. See codex-execution-contract.md and non-entry-execution-contract-template.md for full rules.

input:
  objective: "Send command to target pane and monitor completion"
  contract_extensions: { pane_target: "codex-session:0.1", command_count: 2 }
output:
  status: "completed"
  quality_gate:
    # Caller-supplied; tmux-sender passes this field through without interpreting it.
    gate_id: "caller-quality-gate"
    gate_type: "implementation"
    trigger: "caller-defined validation"
    criteria:
      - "Caller provides a canonical quality gate payload"
      - "Payload is forwarded unchanged"
    result: "pass"
    evidence:
      - "Pane accepted command"
    blockers: []
    branching:
      on_pass: "handoff"
      on_fail: "caller_handles_failure"
      max_cycles: 1
  contract_extensions: { pane_target: "codex-session:0.1", command_count: 2 }

Prerequisites

IMPORTANT: For automatic completion monitoring and notification to work:

1. tmux must be running - Start a tmux session if not already running
2. Claude Code must be running inside tmux - Launch Claude Code in a tmux pane (e.g., multiagent:0.1)
3. Codex runs in a separate pane - Execute Codex in another pane (e.g., codex-session:0.1)

Typical setup:

# Create tmux session with two panes
tmux new-session -s multiagent -n main
tmux split-window -h -t multiagent

# Left pane (0.0): Claude Code
# Right pane (0.1): Codex execution

# Or use separate sessions
tmux new-session -d -s codex-session

If Claude Code is NOT running in tmux, the monitoring script can still detect completion and save results, but automatic notification will not work.

Basic Usage

Check Available Panes

tmux list-panes

Send Commands

❌ Wrong Way:

# This does NOT work
tmux send-keys -t pane:0.1 "command" Enter

✅ Correct Way:

# Send command and Enter separately
tmux send-keys -t pane:0.1 "command"
tmux send-keys -t pane:0.1 Enter

Pane Reference Formats

• pane-number: Simple pane number (e.g., 1)
• session:window.pane: Full specification (e.g., codex-session:0.1)

Common Use Cases

Execute Codex in Another Pane

# Send command to Codex pane
tmux send-keys -t codex-session:0.1 'codex exec --model gpt-5.3-codex "task description"'
tmux send-keys -t codex-session:0.1 Enter

Completion Monitoring Script

Automatically detect completion of long-running tasks (like Codex) and notify Claude Code.

Script Usage

# Basic monitoring (no notification)
scripts/monitor-completion.sh [pane-target] [search-pattern]

# With automatic Claude Code notification
scripts/monitor-completion.sh [pane-target] [search-pattern] [notify-pane]

Parameters

Example Usage

# Start monitoring in background
scripts/monitor-completion.sh \
  codex-session:0.1 \
  "codex exec" \
  multiagent:0.1 &

# Execute Codex command
tmux send-keys -t codex-session:0.1 'codex exec --skip-git-repo-check -m gpt-5.3-codex --config model_reasoning_effort="high" --sandbox workspace-write --full-auto "task description"'
tmux send-keys -t codex-session:0.1 Enter

Script Behavior

1. Process Monitoring: Waits until the specified process pattern terminates (checks every 3 seconds)
2. Result Saving: Saves tmux pane output to /tmp/codex-result-YYYYMMDD-HHMMSS.txt (if save-result=1)
3. Completion Flag: Creates /tmp/codex-completed.flag
4. Notification with Smart Retry:
   • Sends "Codex exec completed. Please check the result." to Claude Code pane
   • Skips notification when target pane is busy (Working/Thinking) if skip-when-working=1
   • Forces notification after N consecutive skips (configurable via force-notify-after-skips)
   • Continues notification loop every notify-interval-sec seconds until killed
5. Idle Detection: Intelligently detects idle state by checking for prompt markers (❯, ›, ? for shortcuts, context left) before checking busy markers

Integration Example: Codex + Auto-monitoring

# Step 1: Launch monitoring script in background
scripts/monitor-completion.sh \
  codex-session:0.1 \
  "codex exec" \
  multiagent:0.1 &

# Step 2: Execute Codex command
tmux send-keys -t codex-session:0.1 'codex exec --skip-git-repo-check -m gpt-5.3-codex --config model_reasoning_effort="high" --sandbox workspace-write --full-auto "implementation task"'
tmux send-keys -t codex-session:0.1 Enter

# On completion:
# - Results are saved automatically
# - Claude Code is awakened with "What happened?"
# - Ready to review results

Completion Notification Contract

• When monitoring detects completion, notify the caller and pass raw Codex stdout unchanged.
• tmux-sender owns completion detection, notification, and output pass-through only.
• Do not parse, validate, or gate on quality_gate in this skill.
• The caller (workflow-entry or Codex skill) is responsible for all quality_gate validation.
• Keep context aligned with non-entry-execution-contract-template.md and quality-gate-evidence-template.md.

Best Practices

1. Session Management

# Create new session
tmux new-session -d -s codex-session

# Split panes
tmux split-window -h -t codex-session

# Attach to session
tmux attach -t codex-session

# Detach (leave session running)
# Press: Ctrl+b, d

2. Error Handling

# Check command success/failure
tmux send-keys -t 1 'command && echo "Success" || echo "Failed"'
tmux send-keys -t 1 Enter

3. Send Long Commands

# Use heredoc
tmux send-keys -t 1 "cat > /tmp/script.sh << 'EOF'
#!/bin/bash
echo 'complex script'
EOF"
tmux send-keys -t 1 Enter
tmux send-keys -t 1 'bash /tmp/script.sh'
tmux send-keys -t 1 Enter

Troubleshooting

Pane Not Found

# Error: can't find pane
# Solution: Use session:window.pane format
tmux send-keys -t codex-session:0.1 "command"

Command Not Executing

# Cause: Enter not sent correctly
# Solution: Always send in two steps
tmux send-keys -t 1 "command"
tmux send-keys -t 1 Enter  # Separate command

Monitoring Script Not Working

# Check 1: Is process running?
ps aux | grep "codex exec"

# Check 2: Is pane reference correct?
tmux list-panes -t codex-session

# Check 3: Does script have execute permission?
chmod +x scripts/monitor-completion.sh

Related Skills

• codex: Codex CLI execution (references tmux execution method)

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