tmux

name	tmux
description	Remote control tmux sessions for interactive CLIs (python, gdb, etc.) by sending keystrokes and scraping pane output.
license	Vibecoded
script	scripts/wait-for-text.sh

tmux Skill

Use tmux as a programmable terminal multiplexer for interactive work. Works on Linux and macOS with stock tmux; avoid custom config by using a private socket.

Script location: ~/.dotfiles/mise/config/pi-coding-agent/agent/skills/tmux/scripts/

CRITICAL: Pane Safety Rules

Never kill or disrupt the pane running pi. Before killing, resizing, or replacing ANY pane:

1. Identify your own pane: Run tmux display-message -p '#{pane_id}' to get the pane pi is running in. Store this — never kill it.

2. Verify target pane before kill: Before kill-pane -t X, confirm X is not your own pane ID.

3. Verify target pane before send-keys: Before sending keys to ANY pane, verify the expected process is actually running there:

   # Check what's running in target pane
   tmux display-message -t "$TARGET" -p '#{pane_current_command}'
   # Or capture last few lines to confirm the right prompt/app
   tmux capture-pane -p -t "$TARGET" -S -5
   

4. Never send keys blindly. If the expected app (python, gdb, w3m, etc.) is NOT in the target pane, STOP and re-discover the correct pane.

5. Never assume pane layout persists. Panes can be rearranged, closed by user, or swapped. Always re-verify before interacting.

Verification pattern (use before every send-keys or kill-pane):

# Get my pane (pi's pane) — do this once at start
MY_PANE=$(tmux display-message -p '#{pane_id}')

# Before interacting with a target
TARGET_CMD=$(tmux display-message -t "$TARGET" -p '#{pane_current_command}' 2>&1)
if [ $? -ne 0 ]; then
  echo "Target pane $TARGET does not exist"
elif [ "$TARGET" = "$MY_PANE" ]; then
  echo "ABORT: target is pi's own pane"
else
  echo "Target running: $TARGET_CMD"
fi

Quickstart (isolated socket)

SOCKET_DIR=${TMPDIR:-/tmp}/claude-tmux-sockets  # well-known dir for all agent sockets
mkdir -p "$SOCKET_DIR"
SOCKET="$SOCKET_DIR/claude.sock"                # keep agent sessions separate from your personal tmux
SESSION=claude-python                           # slug-like names; avoid spaces
tmux -S "$SOCKET" new -d -s "$SESSION" -n shell
tmux -S "$SOCKET" send-keys -t "$SESSION":0.0 -- 'python3 -q' Enter
tmux -S "$SOCKET" capture-pane -p -J -t "$SESSION":0.0 -S -200  # watch output
tmux -S "$SOCKET" kill-session -t "$SESSION"                   # clean up

After starting a session ALWAYS tell the user how to monitor the session by giving them a command to copy paste:

To monitor this session yourself:
  tmux -S "$SOCKET" attach -t claude-lldb

Or to capture the output once:
  tmux -S "$SOCKET" capture-pane -p -J -t claude-lldb:0.0 -S -200

This must ALWAYS be printed right after a session was started and once again at the end of the tool loop. But the earlier you send it, the happier the user will be.

Socket convention

• Agents MUST place tmux sockets under CLAUDE_TMUX_SOCKET_DIR (defaults to ${TMPDIR:-/tmp}/claude-tmux-sockets) and use tmux -S "$SOCKET" so we can enumerate/clean them. Create the dir first: mkdir -p "$CLAUDE_TMUX_SOCKET_DIR".
• Default socket path to use unless you must isolate further: SOCKET="$CLAUDE_TMUX_SOCKET_DIR/claude.sock".

Targeting panes and naming

• Target format: {session}:{window}.{pane}, defaults to :0.0 if omitted. Keep names short (e.g., claude-py, claude-gdb).
• Use -S "$SOCKET" consistently to stay on the private socket path. If you need user config, drop -f /dev/null; otherwise -f /dev/null gives a clean config.
• Inspect: tmux -S "$SOCKET" list-sessions, tmux -S "$SOCKET" list-panes -a.

Finding sessions

• List sessions on your active socket with metadata: ~/.dotfiles/mise/config/pi-coding-agent/agent/skills/tmux/scripts/find-sessions.sh -S "$SOCKET"; add -q partial-name to filter.
• Scan all sockets under the shared directory: ~/.dotfiles/mise/config/pi-coding-agent/agent/skills/tmux/scripts/find-sessions.sh --all (uses CLAUDE_TMUX_SOCKET_DIR or ${TMPDIR:-/tmp}/claude-tmux-sockets).

Sending input safely

• Always verify the target pane has the expected process before sending keys (see Pane Safety Rules above).
• Prefer literal sends to avoid shell splitting: tmux -L "$SOCKET" send-keys -t target -l -- "$cmd"
• When composing inline commands, use single quotes or ANSI C quoting to avoid expansion: tmux ... send-keys -t target -- $'python3 -m http.server 8000'.
• To send control keys: tmux ... send-keys -t target C-c, C-d, C-z, Escape, etc.

Watching output

• Capture recent history (joined lines to avoid wrapping artifacts): tmux -L "$SOCKET" capture-pane -p -J -t target -S -200.
• For continuous monitoring, poll with the helper script (below) instead of tmux wait-for (which does not watch pane output).
• You can also temporarily attach to observe: tmux -L "$SOCKET" attach -t "$SESSION"; detach with Ctrl+b d.
• When giving instructions to a user, explicitly print a copy/paste monitor command alongside the action don't assume they remembered the command.

Spawning Processes

Some special rules for processes:

• when asked to debug, use lldb by default
• when starting a python interactive shell, always set the PYTHON_BASIC_REPL=1 environment variable. This is very important as the non-basic console interferes with your send-keys.

Synchronizing / waiting for prompts

• Use timed polling to avoid races with interactive tools. Example: wait for a Python prompt before sending code:

  ~/.dotfiles/mise/config/pi-coding-agent/agent/skills/tmux/scripts/wait-for-text.sh -t "$SESSION":0.0 -p '^>>>' -T 15 -l 4000
  

• For long-running commands, poll for completion text ("Type quit to exit", "Program exited", etc.) before proceeding.

Interactive tool recipes

• Python REPL: tmux ... send-keys -- 'python3 -q' Enter; wait for ^>>>; send code with -l; interrupt with C-c. Always with PYTHON_BASIC_REPL.
• gdb: tmux ... send-keys -- 'gdb --quiet ./a.out' Enter; disable paging tmux ... send-keys -- 'set pagination off' Enter; break with C-c; issue bt, info locals, etc.; exit via quit then confirm y.
• Other TTY apps (ipdb, psql, mysql, node, bash): same pattern—start the program, poll for its prompt, then send literal text and Enter.

Cleanup

• Kill a session when done: tmux -S "$SOCKET" kill-session -t "$SESSION".
• Kill all sessions on a socket: tmux -S "$SOCKET" list-sessions -F '#{session_name}' | xargs -r -n1 tmux -S "$SOCKET" kill-session -t.
• Remove everything on the private socket: tmux -S "$SOCKET" kill-server.

Helper: wait-for-text.sh

~/.dotfiles/mise/config/pi-coding-agent/agent/skills/tmux/scripts/wait-for-text.sh polls a pane for a regex (or fixed string) with a timeout. Works on Linux/macOS with bash + tmux + grep.

~/.dotfiles/mise/config/pi-coding-agent/agent/skills/tmux/scripts/wait-for-text.sh -t session:0.0 -p 'pattern' [-F] [-T 20] [-i 0.5] [-l 2000]

• -t/--target pane target (required)
• -p/--pattern regex to match (required); add -F for fixed string
• -T timeout seconds (integer, default 15)
• -i poll interval seconds (default 0.5)
• -l history lines to search from the pane (integer, default 1000)
• Exits 0 on first match, 1 on timeout. On failure prints the last captured text to stderr to aid debugging.