Oleksandr Kuzmenko, EditorPublished 7 min readAI-assisted · editor-reviewed
TL;DR
- Claude Code and Codex do not update tmux window titles dynamically; screen inspection via capture-pane is mandatory.
- Process detection must walk descendant PIDs via pgrep because CLI installers run from versioned directories.
- Rule ordering matters: Claude requires working state checks first, while Codex requires approval prompt checks first.
Key facts
- Multiplexing target
- Native tmux status line without replacing multiplexer
- Supported agents
- Claude Code, Codex, Grok, pingme
- Detection technique
- Process-tree traversal + tmux capture-pane terminal scraping
The Fragility of Title and Command Hooks
When multiplexing agent CLI sessions such as Claude Code, Codex, and Grok, developers instinctively look at pane_title or pane_current_command. However, Claude Code sets pane_title once with the session name and never modifies it, ignoring standard OSC status escape updates. Grok emits dynamic braille spinners (⠋, ⠸) in the title, but relying on titles makes cross-agent behavior inconsistent. Furthermore, checking pane_current_command fails because launchers execute versioned binaries (such as 2.1.267 or grok-1.0.30-mac), stripping the recognisable program identity.
Combining Process Trees with Screen Buffer Scraping
The robust pattern pairs process identification with direct terminal buffer inspection:
1. Identify the agent binary: Traverse descendant process IDs via pgrep -P and match the executable name (claude, codex, grok, pingme). 2. Capture visible screen state: Use tmux capture-pane on the bottom lines of the target pane. 3. Apply agent-specific state rules:
- Claude: Treat
esc to interruptasworking, a bare prompt (❯) asidle, and permission queries (do you want to proceed?,waiting for permission) asaction. - Codex: Prioritize approval prompts (
press enter to confirm or esc to cancel) before checkingesc to interruptto prevent busy states from masking user blocking. - Grok: Match interactive footer cues (
<n>/<n>:select,Allow …?) for approvals and[stop]|Ctrl+c:cancelfor execution.
By feeding these evaluation results into your window-status-format, tmux flags stalled or working tasks directly in tab headers without external UI overhead.
Try it in 2 minutes
agent_in_pane() {
local root="$1" pids="$root" queue="$root"
while [ -n "$queue" ]; do
local pid="${queue%% *}"
queue="${queue#$pid}"; queue="${queue# }"
for c in $(pgrep -P "$pid" 2>/dev/null); do
pids="$pids $c"; queue="$queue $c"
done
done
ps -o comm= -p $pids 2>/dev/null | sed -nE 's|.*/||; /^(claude|codex|grok)$/p' | head -n 1
}When to use
- When managing 3 or more concurrent autonomous CLI agents across tmux tabs.
- When coding agents block on shell permission checks out of view.
When NOT to use
- When running agent workloads exclusively within GUI IDEs such as Cursor or Windsurf.
- When you prefer standalone terminal multiplexers designed specifically for agent orchestration.
What to do today
- Add a pgrep process tree walker script to your dotfiles to identify active agent binaries per pane.
- Configure tmux capture-pane pattern matching for 'esc to interrupt' and confirmation prompts.
- Inject custom status icons into the tmux window-status-current-format configuration.
Step names are taken from What to do today.
Step names are taken from What to do today. Add a pgrep process tree walker script to your dotfiles to identify active agent binaries per pane.. Configure tmux capture-pane pattern matching for 'esc to interrupt' and confirmation prompts.. Inject custom status icons into the tmux window-status-current-format configuration.
- Add a pgrep process tree walker script to your dotfiles to identify active agent binaries per pane.
- Configure tmux capture-pane pattern matching for 'esc to interrupt' and confirmation prompts.
- Inject custom status icons into the tmux window-status-current-format configuration.