gh-attach

gh attach uploads a file to GitHub's internal user-attachments endpoint (no public API exists) and prints the URL, which GitHub auto-renders (image/video/file) wherever it's pasted. The URL inherits the repo's visibility, so private-repo uploads stay private.

Prerequisites

gh extension list | grep -q 'gh attach' || gh extension install sudosubin/gh-attach

Uploads use a GitHub browser session cookie, not the gh token. By default, gh must be authenticated so gh-attach can select the matching browser account. If the wrong account is selected, add --browser <name> --profile <name>. For headless use, set GHATTACHSESSIONTOKEN to the bare usersession cookie value. Treat it as a full account credential.

Steps

1. Upload: Use an absolute quoted path. -R is optional inside a repository. For GHES, use -R host/owner/repo. The command prints the URL on one line. GitHub auto-renders it (image/video/file), so use it as-is:

URL=$(gh attach "$FILE" -R <owner>/<repo>)

2. Embed (always --body-file -, e.g. gh pr comment/edit, gh issue comment/edit):

printf '## Screenshots\n\n%s\n' "$URL" | gh pr comment <pr> -R <owner>/<repo> --body-file -

3. Download: Specify the destination explicitly. Private attachments use the active gh token, with browser cookies as an authorization fallback:

gh attach download "$URL" -O "$FILE"

Notes

• Private repo: URL renders only for authorized viewers. An anonymous fetch is expected to return 404 or 403.
• Sizing: embed <img width="800" src="$URL"> instead of the bare URL.
• GitHub Cloud and GHES decide which file extensions and content types they accept.