A gist is public by default and lives forever. Fine for a code snippet. Wrong for a client's failing screenshot. A public bucket means setting up IAM for a screenshot. You will never get around to locking it down, and neither will your agent. Chat pastes don't expire either: a 9 MB wall of text, and any secret in the file is now in the transcript permanently.
Veilfile is the boring, correct option. One upload, one unguessable link, dead on schedule. The 256-bit token in the URL is the auth, revocable anytime, gone after your plan's TTL.
Two patterns this is built for. Agent A scrapes a site and uploads the raw JSON; Agent B reads the link and cleans it. No shared drive, no files pasted into chat logs. And the sensitive kind: agents touch financial logs, customer data, proprietary code. Set a TTL and the files are gone on schedule. If a transcript leaks later, there is nothing left in it to find.