Tooltips could strand on screen when pointerleave didn't fire — fast
flicks off the target, re-renders that yanked the element out mid-
hover, or the tab losing focus. Three guards:
- 5s max-life watchdog on every show, so the worst case is a late
fade rather than a permanent overlay
- pointermove check: if the pointer is no longer over the tip's
owning target (or the target got detached from the DOM), hide
- window blur + visibilitychange also hide immediately
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>