vintlin/computer-care-skills/folder-watch

Folder Watch

Overview

Folder watchers should be explicit about what is watched, what command runs, where logs go, and how failures are reported. Prefer reversible local automation before installing persistent agents.

Workflow

1. Define watched paths and ignore rules. Exclude noisy temporary files (swap files, build artifacts, .DS_Store) by extension or glob. Debounce or filter aggressively — do not restart a service on every transient write.
2. Choose the watcher. Prefer watchexec when available; fall back to a simple polling script otherwise. Always set an explicit working directory (--workdir or cd). On macOS avoid Linux-only flags like find -newermt — use stat -f %m or a portable alternative.
3. Decide event handling. Choose debounce (coalesce rapid changes), restart (kill and re-run on each event), or queue.
4. Capture stdout/stderr to a log file. Make the log path explicit.
5. Add notification only after the command is reliable. Keep credentials out of skill files and scripts — use environment variables, keychain, or a local secret manager. Include command, exit code, log path, and changed file in notifications. Avoid sending sensitive file contents.
6. Test with a harmless file change before enabling persistent automation. Do not install a launchd or systemd watcher until a foreground test succeeds end-to-end.

Quick Examples

Run a command after changes:

watchexec --restart --watch ./src --ext py -- 'python script.py'

Debounce noisy changes:

watchexec --debounce 2s --watch ~/Downloads -- 'echo changed'

Portable recent-file check for macOS:

find . -type f -maxdepth 2 | while read -r file; do
  mtime=$(stat -f %m "$file" 2>/dev/null || stat -c %Y "$file" 2>/dev/null || echo 0)
  now=$(date +%s)
  [ $((now - mtime)) -le 60 ] && printf '%s\n' "$file"
done