[sonichi]

Summary

Per your "y" at 21:00Z in #dev: Sutando.app's watcher-auto-restart (PR #444) depends on a tmux-wrapped CLI pane to send watcher keystrokes when the task-watcher dies. If tmux is missing on a first-run machine, startup.sh falls back to a bare exec claude — functional, but silently drops the auto-restart feature.

Change

5-line guard in src/startup.sh:294: if tmux is missing AND Homebrew is available, install tmux before wrapping the CLI. Preserves the existing bare-exec fallback when both are absent.

  if ! command -v tmux > /dev/null 2>&1 && command -v brew > /dev/null 2>&1; then
    echo "tmux not found — installing via Homebrew (required for Sutando.app watcher-auto-restart)..."
    brew install tmux 2>&1 | tail -3
  fi

Test plan

• bash -n src/startup.sh clean
• Manual: on a machine without tmux + with Homebrew, bash src/startup.sh should auto-install then proceed to tmux wrap (no user prompt, no failed step)
• Manual: existing-tmux machines should see zero behavior change

Scope

Doesn't touch the "neither tmux nor brew" path — that branch already has a helpful warning pointing at brew install tmux, just skipped now by the Homebrew short-circuit.

🤖 Generated with Claude Code

[sonichi]

LGTM. Small, isolated, backward compatible.

Logic verified:

• Guard checks both command -v tmux missing AND command -v brew present → only auto-installs when Homebrew is available, respects existing assumptions.
• brew install tmux 2>&1 | tail -3 truncates noise.
• Subsequent if command -v tmux fallthrough still catches "install failed or brew absent" → bare exec claude with warning.
• Preserves the intent of PR #444's auto-restart feature for first-run users without tmux.

Minor nit (not blocking): brew install tmux can take 30+ seconds on first run, and | tail -3 hides progress during that window. Consider printing a one-liner before the pipe if you want to signal "this may take a moment":

echo "tmux not found — installing via Homebrew (~30s)..."

(already close to what you have — just the "~30s" hint helps users not think it's hung). Totally optional.

No behavior change when tmux is already present. bash -n clean per Mini's PR body.