Written by Claude Code, reviewed by me.
## Summary
Fixes `@claude` to work on external fork PRs by:
1. Restricting triggers to modelcontextprotocol org members only
2. Properly checking out fork PR code via `refs/pull/N/head`
## Background
The `@claude` GitHub app was failing on external forks
([example](https://github.com/modelcontextprotocol/registry/actions/runs/19938435814/job/57169634431))
because the action tried to fetch branches by name, which doesn't work
for forks.
## Changes
### Org membership check
- Fetches the member list from
[`modelcontextprotocol/access`](https://github.com/modelcontextprotocol/access)
repo's `users.ts`
- Only org members can trigger `@claude` (prevents strangers from using
it)
- Uses `github.triggering_actor` so the person commenting must be an org
member
### Fork PR checkout fix
- Detects when a comment is on a fork PR
- Uses `refs/pull/{number}/head` to checkout fork code (instead of
branch name)
- This works because GitHub exposes all PRs via special refs on the base
repo
## How it works
1. Org member comments `@claude` on a fork PR
2. Workflow checks if commenter is in the `modelcontextprotocol/access`
member list
3. Workflow detects it's a fork PR and checks out via `refs/pull/N/head`
4. Claude runs with access to the fork's code
🤖 Generated with [Claude Code](https://claude.com/claude-code)
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Co-authored-by: Claude <noreply@anthropic.com>
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