Support attaching PDFs to GitHub issues from Copilot CLI #5136

Describe the feature or problem you'd like to solve

Allow Copilot CLI to upload and attach PDF documents to GitHub issues, matching the attachment capability available in the GitHub browser issue editor.

This is about uploading a document to a GitHub issue, not attaching a PDF to a Copilot conversation for model analysis.

Proposed solution

Provide a supported workflow for uploading PDFs when creating or updating GitHub issues and inserting the resulting attachment link into the issue body or a comment.

The reported current workflow relies on gh issue ... --attach, which accepts images/videos but rejects PDFs. If PDF support requires an upstream GitHub CLI change, track that dependency and update Copilot's attachment tooling/instructions when it becomes available. Until then, explain the limitation and browser workaround explicitly rather than implying that GitHub issues cannot accept PDFs.

Expected behavior: a user can ask Copilot to attach a local PDF to an issue without switching to the browser or hosting the document elsewhere. Respect GitHub's supported file types, size limits, authentication, and upload permissions.

Example prompts or workflows

1. "Create an issue describing this bug and attach ./reproduction.pdf."
2. "Attach ./design-spec.pdf to issue 0.0.329 #123 and reference it in the issue description."
3. "Add a comment to issue 0.0.329 #123 with ./investigation-report.pdf attached."

Additional context

A support-thread reproduction reported the following with GitHub CLI 2.100.0:

• gh issue ... --attach rejects .pdf locally, before any upload.
• Its supported-file list contains images and videos only.
• Dragging the same PDF into the browser issue editor succeeds and produces an attachment link that can subsequently be reused from the CLI.

These observations are reported from the supplied conversation; they have not been independently reproduced while filing this issue.

References:

• GitHub CLI issue create manual
• GitHub browser attachment documentation

Duplicate search covered open and closed issues involving PDFs, attachments, uploads, and the built-in media skill. #4583 concerns PDF input/analysis in Copilot conversations, not uploading PDFs to GitHub issues; #3375 concerns associating CLI sessions with issues, not document attachments. No matching issue was found.