A focal point is two finite numbers

float.TryParse takes "NaN" and "Infinity", and Math.Clamp keeps a NaN, so `focus=NaN,NaN` on an upload or a media PUT
was stored as given. Once the media was posted, every status and timeline response holding the post, and the Note
and its delivery, failed to serialise, for every viewer. FocalPoint.Parse takes finite numbers only (anything else is
ignored, as an unreadable focus was); the mapper and the renderer leave out a focus that isn't sound, and migration
_016 removes the ones stored before, from the uploads and from the copy each post keeps. What PrivaPub sends is
unchanged for any focus that could be sent before.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

CLAUDE.md

@@ -307,7 +307,9 @@ group www-data and reaches the private mongod; `sudo -u www-data` works too.
      and never cached. That is how remote video plays.
 
    nginx has a `/media/proxy/` location with `proxy_buffering off` and a 600 s read timeout for those streams.
-5. **Remote video and audio become one playable attachment** in the Mastodon API (`MastodonMapper.Playable`): the best MP4
+5. **A focal point is two finite numbers** within -1..1 (`FocalPoint.Parse`); anything else is ignored. A stored NaN made
+   every status, timeline and Note holding its post fail to serialise; migration `_016` removed the ones stored before.
+6. **Remote video and audio become one playable attachment** in the Mastodon API (`MastodonMapper.Playable`): the best MP4
    up to 720p that carries both sound and picture, including PeerTube's fragmented files inside an HLS entry. HLS
    playlists themselves are not rewritten.