docs(hub): say what the subtitle track's mode effect was measured to do

The comment claimed a <track> appended after playback started is not shown by
its `default` attribute. Chrome shows it: in a headless run the TextTrack read
back "showing" before the effect had touched it, with its cues already parsed.

The effect stays, for the two reasons that are true — `default` says nothing
about turning subtitles off again, and an explicitly assigned mode means the
same thing in every engine — but the reason written beside it was not one of
them.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UGY17EPph5LsLzePPXhUVc

1 files changed, 9 insertions, 5 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/video-player.js b/packages/meshbay-hub/src/meshbay_hub/static/video-player.js
index 5725fc4..a150512 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/video-player.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/video-player.js
@@ -1122,11 +1122,15 @@ function VideoPlayer({ entry, transportRef, gekRef, onClose, onDownload }) {
     }
   }, [entry, transportRef, gekRef]);
 
-  // A <track> added to a media element after it started playing is not shown
-  // by the `default` attribute — that one is read when the element is first
-  // parsed, and by then this track did not exist. The mode has to be set on
-  // the live TextTrack, which only appears once the element has adopted the
-  // child preact just rendered.
+  // The mode is set here rather than left to the `default` attribute.
+  //
+  // Chrome does honour `default` on a track appended long after playback
+  // started — measured in a headless run, where the TextTrack read back
+  // "showing" before this effect had touched it, and its cues were parsed.
+  // That was worth checking and is not what this exists for: `default` has
+  // nothing to say about turning subtitles *off* again, which is the other
+  // half of this effect, and a mode assigned here means the same thing in
+  // every engine whatever each one decides the attribute implies.
   useEffect(() => {
     const v = videoRef.current;
     if (!v) return;