helpers.go was gitignored as "stale WIP" but defines BufferSystemEvent
called by committed code in install.go and loop.go — CI broke because
the file never shipped.
buffer.go GetBufferedEvents: re-atomic the read+clear under one lock
hold; the refactor split into ReadBufferedEvents+Clear introduced a
window where BufferEvent could write events that Clear then deletes.
4e08deef8c