docs(skills): add parallel Codex orchestration learnings

- coding-agent: document --yolo flag, git worktree + tmux pattern
- tmux: add section on orchestrating coding agents in parallel

Learnings from running 5 parallel Codex sessions to analyze GitHub issues

skills/tmux/SKILL.md

@@ -65,6 +65,41 @@ To monitor:
 - tmux is supported on macOS/Linux. On Windows, use WSL and install tmux inside WSL.
 - This skill is gated to `darwin`/`linux` and requires `tmux` on PATH.
 
+## Orchestrating Coding Agents (Codex, Claude Code)
+
+tmux excels at running multiple coding agents in parallel:
+
+```bash
+SOCKET="${TMPDIR:-/tmp}/codex-army.sock"
+
+# Create multiple sessions
+for i in 1 2 3 4 5; do
+  tmux -S "$SOCKET" new-session -d -s "agent-$i"
+done
+
+# Launch agents in different workdirs
+tmux -S "$SOCKET" send-keys -t agent-1 "cd /tmp/project1 && codex --yolo 'Fix bug X'" Enter
+tmux -S "$SOCKET" send-keys -t agent-2 "cd /tmp/project2 && codex --yolo 'Fix bug Y'" Enter
+
+# Poll for completion (check if prompt returned)
+for sess in agent-1 agent-2; do
+  if tmux -S "$SOCKET" capture-pane -p -t "$sess" -S -3 | grep -q "❯"; then
+    echo "$sess: DONE"
+  else
+    echo "$sess: Running..."
+  fi
+done
+
+# Get full output from completed session
+tmux -S "$SOCKET" capture-pane -p -t agent-1 -S -500
+```
+
+**Tips:**
+- Use separate git worktrees for parallel fixes (no branch conflicts)
+- `pnpm install` first before running codex in fresh clones
+- Check for shell prompt (`❯` or `$`) to detect completion
+- Codex needs `--yolo` or `--full-auto` for non-interactive fixes
+
 ## Cleanup
 
 - Kill a session: `tmux -S "$SOCKET" kill-session -t "$SESSION"`.