Matching on the video id let a stale request land when the user left
and returned to the same video, or saved an edit while the page's
first description request was still in flight. Each fetch now takes a
generation number and only the newest generation may write state,
per value, so a description refetch never invalidates a comments
request.
The edit dialog adopts a description that arrives while it is open
only if the user has not typed, so a draft written over the
placeholder is not wiped by the empty or failed value that follows.
Tests: 7 -> none -> 8 -> 7 with the first request rejecting last; a
save refetch beating the initial request; the draft surviving; the
pending placeholder asserted; the console spy restored in finally.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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