Attach images/videos to discussions and PRs (like gh --attach) #5111

low prio

The latest gh release (2.102) added an --attach flag to gh pr create and gh pr edit:

gh pr create --attach './before.png#Before the fix' --attach ./after.png

It uploads the files to GitHub and puts them in the PR body. If the body already references a file (![alt](./before.png)), that reference is rewritten to the uploaded URL. Otherwise the image is appended. Very handy, especially for agents opening PRs with screenshots.

There's no equivalent in huggingface_hub today. When you drag an image into a discussion or PR comment box on the Hub, the web editor uploads it to https://huggingface.co/uploads and inserts the returned cdn-uploads.huggingface.co URL as markdown. From Python or the hf CLI, the only way to get the same result is to call that endpoint by hand:

URL=$(curl -s -X POST https://huggingface.co/uploads -H "Content-Type: image/png" --data-binary @shot.png)

and then paste ![shot]($URL) into the description passed to create_discussion or create_commit(..., create_pr=True). It works, but it's undocumented and every script (or agent) has to rediscover it.

Proposal

• Python: HfApi.upload_attachment(path) -> str, returning the CDN URL.
• CLI: a repeatable --attach FILE[#alt text] option on hf discussions create (including --pr), hf discussions comment and hf discussions edit, with the same behavior as gh: rewrite ./file references in the body, append the others.
• Maybe later: the same option on hf upload --create-pr, for the PR description.
• Check the file type client-side against what the Hub editor accepts (PNG, JPEG, GIF, WebP, MP4, MOV, WebM, MP3, WAV). SVG is not accepted.

Open question (Hub side)

The upload endpoint doesn't take a token: files uploaded outside the browser end up under .../uploads/noauth/... instead of being tied to the user's account. Before exposing this as a public API, it would be good to have the endpoint accept a regular Authorization: Bearer token so uploads are attributed to the user.