remote-tmux

Remote work via tmux (ssh exactly once)

Never use one-shot ssh host 'cmd' invocations. All remote work goes through the pattern below; the entire task chain performs ssh exactly once, at step 2.

Core idea

A local tmux session sshes into the remote host → open another tmux layer on the remote side → start a claude session inside it → from then on, all work is "send a prompt to the remote claude". If the connection drops, the remote tmux survives; attach again and continue.

One-time connection setup (once per task chain)

1. Exclusive session name: S=<agent>_<purpose> (e.g. myagent_train). Never reuse a session another agent is using — you would interleave commands, fight over the pane, and mix outputs. Check first with tmux has-session -t "$S" 2>/dev/null; if it exists and belongs to your own task chain, skip straight to "Sending prompts".

2. Open the local tmux and ssh (the only ssh of the whole workflow):

   tmux new-session -d -s "$S" -x 220 -y 50
   tmux send-keys -t "$S" 'ssh <host>' Enter
   

3. Wait for login (end-marker with bounded polling, never a fixed sleep):

   tmux send-keys -t "$S" 'echo MARK_login_END' Enter
   for i in $(seq 1 30); do
     tmux capture-pane -p -t "$S" | grep -q MARK_login_END && break; sleep 2
   done
   

4. Open the remote tmux + claude session:

   tmux send-keys -t "$S" 'tmux new -A -s '"$S" Enter
   # after a marker confirms you are inside the remote tmux:
   tmux send-keys -t "$S" 'cd <remote-workdir> && claude' Enter
   

   Wait until claude has finished starting (the input box / prompt appears in capture-pane) before sending the first prompt.

Sending prompts / commands

• Send the text and the Enter separately; send the text with -l (literal, so tmux does not interpret ;, $, etc.):

  tmux send-keys -t "$S" -l '<prompt or command text>'
  sleep 1
  tmux send-keys -t "$S" Enter
  

• When sending commands to a remote shell (not claude), append a unique marker: …; echo MARK_<uniq>_END. Use a fresh suffix for every command so you never match a stale marker from a previous one.

Reading output / detecting completion

• Read: tmux capture-pane -p -t "$S" (add -S -2000 for scrollback history).
• Completion: bounded polling for the marker (shell commands) or for claude's output state; always set an upper bound on the wait. For long jobs, judge completion by artifacts (files appearing, byte counts growing), not by guessing from pane text.

Teardown and discipline

• Keep the tmux alive: do not kill the session while the task chain is unfinished. Only after everything is confirmed done, tmux kill-session -t "$S" locally; the remote tmux is usually left in place for later inspection.
• Never pkill -f; never kill -9 remote CUDA processes.
• Never fall back to one-shot ssh host 'cmd' — even read-only probes go through the established session.