i understand all of the work you've done and i greatly appreciate you Fishcake. however, i don't think your customer wants to hear that it just won't work. there has to be something that can be done to make this easier for people.
1. User selects video in client
2. Client uploads to blossom server
3. Server returns: original hash immediately
4. User can publish note right away with original hash
5. Server transcodes in background
6. Later: client polls or server webhooks when derivatives ready
7. Client prompts user (or auto-signs if authorized) the derivative manifest
8. Manifest event published, linking original → derivatives
why wouldn't that work?