zmx Process Management Skill

zmx Process Management

Session Rules

Check zmx list --short before creating sessions — duplicates cause port conflicts and confusing output
Derive session name from git rev-parse --show-toplevel — hardcoded names collide when multiple agent instances run concurrently
Use zmx run to send commands without attaching — zmx attach blocks the agent's shell and makes it unresponsive
Use separate sessions with a common project prefix for multiple processes

One project = one session prefix. Multiple processes = multiple sessions sharing the prefix.

Session Naming

PROJECT=$(basename "$(git rev-parse --show-toplevel 2>/dev/null)" || basename "$PWD")

All subsequent examples assume PROJECT is set. Session names follow ${PROJECT}-<role>:

myapp-server, myapp-tests, myapp-tilt

Starting Processes

SESSION="${PROJECT}-server"

# Idempotent: skip if already running
if ! zmx list --short 2>/dev/null | grep -q "^${SESSION}$"; then
  zmx run "$SESSION" 'npm run dev'
fi

For multiple processes, loop over name:command pairs:

for name_cmd in "server:npm run dev" "tests:npm run test:watch"; do
  name="${name_cmd%%:*}"
  cmd="${name_cmd#*:}"
  SESSION="${PROJECT}-${name}"
  if ! zmx list --short 2>/dev/null | grep -q "^${SESSION}$"; then
    zmx run "$SESSION" "$cmd"
  fi
done

Sending Commands

# Run a command in a session (creates session if needed)
zmx run "${PROJECT}-main" 'cat README.md'

# Pipe via stdin
echo "ls -lah" | zmx r "${PROJECT}-main"

Monitoring Output

zmx history "${PROJECT}-server"                              # full scrollback
zmx history "${PROJECT}-server" | tail -50                   # last 50 lines
zmx history "${PROJECT}-server" | rg -i "error|fail"         # check for errors
zmx history "${PROJECT}-server" | rg -i "listening|ready"    # check for ready

Waiting for Completion

zmx wait "${PROJECT}-tests"                                  # block until done
zmx wait "${PROJECT}-build" "${PROJECT}-lint"                 # wait for multiple

Lifecycle

zmx list                                                     # all sessions
zmx list --short                                             # names only
zmx kill "${PROJECT}-server"                                 # kill one session

# Kill all project sessions
zmx list --short 2>/dev/null | grep "^${PROJECT}-" | while read -r s; do
  zmx kill "$s"
done

Isolation

Only kill sessions matching the current project prefix — other agent instances may have their own sessions running
Always verify the session name before kill operations

When to Use zmx

| Scenario | Use zmx? | |----------|----------| | tilt up | Yes, always | | Dev server (npm run dev, rails s) | Yes | | File watcher (npm run watch) | Yes | | Test watcher (npm run test:watch) | Yes | | Database server | Yes | | One-shot build (npm run build) | No | | Quick command (<10s) | No | | Need stdout directly in conversation | No |

Polling for Readiness

for i in {1..30}; do
  if zmx history "${PROJECT}-server" 2>/dev/null | tail -20 | rg -q "listening|ready"; then
    echo "Server ready"
    break
  fi
  sleep 1
done

Agent Skills: zmx Process Management

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