VdustR GitHub Platform Behavior
Route
- Putting an image, video, or file into an issue, PR, comment, discussion, or
README: read
references/attachments.md. - Getting markdown to render the way you intend, especially inline video: read
references/markdown-rendering.md.
Media upload through the supported path needs an authenticated GitHub CLI v2.99.0 or later. Non-media attachment upload also needs a browser signed in to GitHub and a way to run scripts in its page context. Confirm what the chosen path needs before promising the result, and never treat choosing the upload method as authorization to publish.
Start from the credential
What you can reach depends on which credential you hold, and the difference is not obvious from the error message.
| Credential | Reaches |
|---|---|
| GitHub CLI OAuth token, classic PAT | REST and GraphQL, plus gh --attach media upload |
A workflow's built-in GITHUB_TOKEN |
REST and GraphQL for its own repository; media upload is unverified |
| A logged-in browser session | Everything above, plus web-only flows gated on a per-page nonce |
Some GitHub endpoints are deliberately reachable only from a real page load. They
require a github-verified-fetch: true header and an x-fetch-nonce issued to
that page, so no token substitutes for a session. Non-media attachment upload is
one of them. When an endpoint refuses a valid token, check for that gate before
assuming a permissions problem.
Test rendering without posting
POST /markdown renders arbitrary markdown in a repository's context and returns
the HTML. Use it to confirm what a surface will do before creating an issue or a
comment.
gh api -X POST /markdown -f mode=gfm -f context=<owner>/<repo> --field text=@draft.md \
| grep -oE '<(video|img|a)[^>]*'
To check what an existing issue or comment actually produced, ask for the rendered body instead of guessing from the source:
gh api repos/<owner>/<repo>/issues/<n> -H "Accept: application/vnd.github.html+json" --jq '.body_html'
Prefer the supported media path
For a local image or video bound for an issue, pull request, or comment, use the
repeatable --attach flag on gh issue create, gh issue edit,
gh issue comment, gh pr create, gh pr edit, or gh pr comment. Read
references/attachments.md for version, permissions, partial-failure, body
rewrite, and fallback behavior. Do not reconstruct the upload request when the
supported CLI path is available.
Verify before claiming a limit
GitHub's documented file-type and size lists describe the web interface. Endpoints
enforce their own, narrower rules, and the two disagree. Probe the endpoint with a
throwaway file in a scratch repository rather than reading the docs and asserting
the result. references/attachments.md records what the probes returned.
Related skills
vp-gitfor Git changes and ordinary pull-request lifecycle work.vp-stacked-prfor dependent pull requests or branches.vp-recordingwhen the attachment must first be captured, recorded, or rendered.vp-pr-comment-resolverfor author-side PR discussion and review threads.