Transfer and message delivery are separate
An upload produces a temporary file result that is later used to send media. Completion of the upload does not prove delivery. Chunk sizing, alignment, concurrency and large-file methods have constraints; configured part limits also matter. Files larger than 10 MB use the large-file upload flow. Consult the file reference for exact parameters.
A temporary upload identifier is not a permanent storage guarantee.
Retain the source of a file reference
A file_reference can expire and is not the file ID. Refreshing it requires knowing the message or other source where the file was encountered. Preserve that context, and do not interchange photo and document representations blindly.
Implementation recommendations
Track uploading, sending, downloading and local persistence separately. Reconcile an uncertain send result; refresh an expired reference from its source before unnecessarily uploading the file again. Apply access controls, storage quotas and cleanup policies. A progress display should reflect transfer progress rather than a decorative countdown.