Summary

Replace the hardcoded PollingObserver with watchdog's platform-default Observer in the livereload server. This fixes live reload on Linux and WSL2, where PollingObserver silently fails to detect file changes on ext4 filesystems.

Problem

properdocs serve does not live-reload on WSL2 (and potentially other Linux configurations). The root cause is that PollingObserver uses periodic stat() calls, which don't reliably reflect file changes on WSL2's ext4 filesystem. The browser never reloads, even though inotifywait and watchdog's native InotifyObserver both detect changes instantly.

Related upstream: mkdocs/mkdocs#4081

Fix

Use watchdog.observers.Observer instead of watchdog.observers.polling.PollingObserver. The Observer class is watchdog's documented public API and auto-selects the best backend per platform:

• Linux: InotifyObserver (kernel inotify -- instant, zero CPU overhead)
• macOS: FSEventsObserver (instant)
• Windows: WindowsApiObserver (instant)
• Fallback: PollingObserver (if native observer unavailable)

Symlink support

Native observers (inotify, FSEvents) don't follow symlinks the way stat()-based polling does. To preserve the existing symlink behavior, watch() now:

1. Resolves the watched path with os.path.realpath() so symlinked directories are watched at their real location.
2. Scans the watched tree for symlinks pointing outside it, and adds filtered watches on their target directories. The filter ensures only actual symlink targets trigger rebuilds (not unrelated files in the same directory).
3. Cleans up extra watches in unwatch().

Changes

Testing

• All existing tests pass, including the 3 symlink-related tests (test_watches_direct_symlinks, test_watches_through_symlinks, test_watches_through_relative_symlinks)
• hatch run all passes (style, types, unit tests, integration tests)
• 737 tests, 0 failures