Classify link, permission and content failures
An attachment reference and a bearer-style download URL are different things. Store a controlled file identity and access method, not a private URL in broadly shared logs. The following failures are synthetic; the actual provider determines expiry and refresh behaviour.
| Observation | Check | Recovery |
|---|---|---|
| Link expired | Stable file identity still exists | Request authorised new link |
| Access refused | Consumer still has required permission | Resolve authority; do not expose file publicly |
| Downloaded bytes differ | Expected revision/hash changed | Hold and confirm intended file revision |
Verify the resumed file identity
Before retrying upload, compare the retrieved identity and revision with the queued task. Do not attach a newly replaced document merely because its filename is unchanged. Restrict temporary storage and remove it according to the approved operational policy.
The renewed link returns revision 3 while the request approved revision 2. Should transfer continue?
Show the worked answer
Hold the transfer and ask whether revision 3 is authorised or revision 2 must be retrieved. Preserve the original task and document decision.