Returns undefined until a thumbnail is available. On resolution, returns an object
URL that is automatically revoked when the component unmounts or the file changes.
No work happens while visible is false — off-screen items cost nothing.
Cache hits are returned from IndexedDB without running any generator.
Cache misses pick the first matching generator and queue its work so only one
generator runs at a time across all hook instances.
When visible flips back to false (or the hook unmounts), queued and
in-flight generation is aborted so it can't delay other items.
Resolve a thumbnail URL for a file.
Returns
undefineduntil a thumbnail is available. On resolution, returns an object URL that is automatically revoked when the component unmounts or the file changes.visibleisfalse— off-screen items cost nothing.visibleflips back tofalse(or the hook unmounts), queued and in-flight generation is aborted so it can't delay other items.