docs: Add fork support reference page

[Copilot]

No documentation existed explaining how gh-aw behaves in forked repositories. Per the actual implementation, running workflows inside a fork is not supported — all jobs skip via the !github.event.repository.fork condition injected at compile time.

Changes

• docs/src/content/docs/reference/fork-support.md (new): Covers two distinct fork scenarios:
  • Running in a fork — not supported, jobs are skipped gracefully
  • Inbound PRs from forks — blocked by default; use forks: frontmatter to allow trusted forks with glob patterns ("owner/*", "owner/repo", "*")
  • Compatibility table, security warning for broad allowlists, and known limitations
• docs/astro.config.mjs: Adds "Fork Support" entry at the bottom of the Reference sidebar section

---
on:
  pull_request:
    types: [opened, synchronize]
    forks:
      - "trusted-org/*"
      - "partner/specific-fork"
---

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[plan] Add fork support documentation page</issue_title>
<issue_description>## Context

Closes part of #18481 — gh-aw in forks.

There is currently no documentation explaining how gh-aw behaves in forked repositories, what works, what doesn't, and how to set things up correctly.

Objective

Add a documentation page on fork support under docs/ covering the compatibility matrix, required setup steps for fork users, and explanation of design decisions.

Approach

1. Create a new documentation page, e.g., docs/src/content/docs/guides/fork-support.md (follow the existing Diátaxis/Starlight conventions used in docs/).

2. The page should include:

   • Overview: two fork scenarios (inbound fork PRs vs. running gh-aw in a fork)

   • Compatibility table (based on the scout report):

     Feature	Status in Fork	Notes
     pull_request fork filtering	✅ Works	Compiler injects repo ID check
     workflow_run cross-fork safety	✅ Works	Fork check injected at compile time
     Running your own workflows	⚠️ Partial	Must configure own secrets
     Agentic maintenance	⚠️ Skipped	Fork detection added; skips gracefully
     Slash commands	⚠️ Partial	Works if secrets configured
     Secrets	❌ Not inherited	Must reconfigure in fork settings

   • Setup guide: step-by-step for configuring required secrets in a fork

   • forks: frontmatter field: explanation of allow-listing trusted forks

   • Known limitations: features that won't work regardless of secret setup

3. Reference the documentation skill (skills/documentation.md) for style/format guidelines.

4. Verify the page renders correctly in the docs site structure.

Files to Create/Modify

• docs/src/content/docs/guides/fork-support.md (new)
• Possibly update docs/src/content/docs/guides/ index or sidebar config

Acceptance Criteria

• New documentation page exists covering the two fork scenarios
• Compatibility table present with accurate status
• Setup guide covers all required secrets
• forks: frontmatter field documented
• Page follows existing docs style and Diátaxis conventions
  Related to Using gh-aw in forks of repositories #18481

Generated by Plan Command for issue #18481

• expires on Feb 28, 2026, 4:18 PM UTC

Comments on the Issue (you are @copilot in this section)

@pelikhan @copilot forks are not supported. Agentic Workflows will try to cancel all actions but they will not run agents.

• Fixes [plan] Add fork support documentation page #18521

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[pelikhan]

@copilot move guide to the reference section (bottom)

[Copilot]

@copilot move guide to the reference section (bottom)

Done in 4c7fe52 — moved to docs/src/content/docs/reference/fork-support.md and added at the bottom of the Reference section in the sidebar.

[Copilot]

Pull request overview

This PR adds comprehensive documentation on how GitHub Agentic Workflows behaves in forked repositories, addressing a gap in the existing documentation.

Changes:

• New reference documentation page explaining two fork scenarios: running workflows inside a fork (not supported, jobs skip) and handling inbound PRs from forks (blocked by default, configurable via forks: field)
• Sidebar navigation updated to include the new "Fork Support" reference page

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
docs/src/content/docs/reference/fork-support.md	New reference page documenting fork behavior, including automatic job skipping in forks and forks: frontmatter configuration for trusted fork PRs
docs/astro.config.mjs	Adds "Fork Support" entry to Reference section sidebar navigation

Comments suppressed due to low confidence (1)

docs/src/content/docs/reference/fork-support.md:23

• The note suggests that forking a repository will allow workflows to run because "the workflows will then run in your copy of the repository, which is not a fork from GitHub Actions' perspective." However, this statement may be misleading.

When you fork a repository on GitHub and then fork it again to your own account, GitHub still considers it a fork (the github.event.repository.fork property will be true). The workflows will still be skipped.

The intended meaning appears to be that if you want to use agentic workflows in your own independent project, you should copy the implementation rather than using GitHub's fork feature. Consider clarifying this to avoid confusion, for example: "To run agentic workflows in your own repository, create an independent repository (not a GitHub fork) and configure your own secrets."

> [!NOTE]
> To run agentic workflows in your own repository, fork the upstream repo and configure your own secrets — the workflows will then run in your copy of the repository, which is not a fork from GitHub Actions' perspective.

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