name: Claude Code

on:
  issue_comment:
    types: [created]
  pull_request_review_comment:
    types: [created]
  issues:
    types: [opened, assigned]
  pull_request_review:
    types: [submitted]

jobs:
  claude:
    if: |
      (
        (github.event_name == 'issue_comment' &&
          contains(github.event.comment.body, '@claude') &&
          contains(fromJSON('["OWNER", "MEMBER", "COLLABORATOR"]'), github.event.comment.author_association)) ||
        (github.event_name == 'pull_request_review_comment' &&
          contains(github.event.comment.body, '@claude') &&
          contains(fromJSON('["OWNER", "MEMBER", "COLLABORATOR"]'), github.event.comment.author_association)) ||
        (github.event_name == 'pull_request_review' &&
          contains(github.event.review.body, '@claude') &&
          contains(fromJSON('["OWNER", "MEMBER", "COLLABORATOR"]'), github.event.review.author_association)) ||
        (github.event_name == 'issues' &&
          (contains(github.event.issue.body, '@claude') || contains(github.event.issue.title, '@claude')) &&
          contains(fromJSON('["OWNER", "MEMBER", "COLLABORATOR"]'), github.event.issue.author_association))
      )
    runs-on: ubuntu-latest
    permissions:
      contents: read
      pull-requests: read
      issues: read
      id-token: write
      actions: read
    steps:
      # Actions are pinned to full commit SHAs rather than mutable major tags:
      # this job holds ANTHROPIC_API_KEY and grants the agent Bash, so a
      # force-moved tag would be an unreviewed code change inside a
      # secret-holding job. The trailing `# vX.Y.Z` comment is the form
      # Dependabot reads, so pinning costs us no upgrade automation. (#1882)
      - name: Get PR details
        if: |
          (github.event_name == 'issue_comment' && github.event.issue.pull_request) ||
          github.event_name == 'pull_request_review_comment' ||
          github.event_name == 'pull_request_review'
        id: pr
        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
        with:
          script: |
            let prNumber;
            if (context.eventName === 'issue_comment') {
              prNumber = context.issue.number;
            } else {
              prNumber = context.payload.pull_request.number;
            }

            const pr = await github.rest.pulls.get({
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: prNumber
            });

            // A fork PR's head lives in a different repository — or in none at
            // all, if the fork was deleted after the PR was opened (`head.repo`
            // is then null). Neither is ours to check out, so both count as a
            // fork here and the steps below decline rather than guess.
            const headRepo = pr.data.head.repo?.full_name ?? null;
            const isFork = headRepo !== `${context.repo.owner}/${context.repo.repo}`;

            core.setOutput('sha', pr.data.head.sha);
            core.setOutput('is_fork', String(isFork));

      # A fork PR's head is untrusted code, and checking it out would put it in
      # reach of a tool-enabled agent run holding ANTHROPIC_API_KEY. Reviewing
      # the base tree instead would only trade that for a confident review of
      # the wrong tree, so decline visibly and leave the reason in the run.
      - name: Decline fork PR
        if: steps.pr.outcome == 'success' && steps.pr.outputs.is_fork == 'true'
        run: |
          {
            echo "### Claude Code declined this pull request"
            echo
            echo "The head branch lives in a fork, so its code is not checked out and Claude is not run."
            echo "Push the branch to this repository and re-trigger if a review is needed."
          } >> "$GITHUB_STEP_SUMMARY"

      # No `repository:` — a same-repo head is all that reaches this step, and
      # checkout defaults to `github.repository`, which no PR can influence.
      - name: Checkout PR branch
        if: steps.pr.outcome == 'success' && steps.pr.outputs.is_fork == 'false'
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          ref: ${{ steps.pr.outputs.sha }}
          fetch-depth: 0

      # `skipped` means the trigger was an issue or a non-PR comment, so there
      # is no head to check out and the base tree is the right one. The lookup
      # having *failed* is deliberately not included: this condition carries no
      # status-check function, so GitHub applies an implicit `success()` and
      # skips the step after a failed prior step anyway. Spelling out `skipped`
      # keeps that from having to be re-derived by the next reader.
      - name: Checkout repository
        if: steps.pr.outcome == 'skipped'
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          fetch-depth: 0

      - name: Run Claude Code
        # Runs only against a tree this workflow actually checked out: the base
        # repo (non-PR trigger) or a same-repo PR head. A fork PR reaches here
        # with `is_fork == 'true'` and both disjuncts false, so it is skipped.
        if: steps.pr.outcome == 'skipped' || steps.pr.outputs.is_fork == 'false'
        id: claude
        uses: anthropics/claude-code-action@5ef2e550a465a721f4f45e4a7d3c340c873e1dcc # v1.0.190
        with:
          anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}

          # Allow Claude to read CI results on PRs
          additional_permissions: |
            actions: read

          # Trigger when assigned to an issue
          assignee_trigger: "claude"

          claude_args: |
            --mcp-config .mcp.json
            --allowedTools "Bash,mcp__mcp-docs"
            --append-system-prompt "If posting a comment to GitHub, give a concise summary of the comment at the top and put all the details in a <details> block. When working on MCP-related code or reviewing MCP-related changes, use the mcp-docs MCP server to look up the latest protocol documentation. For schema details, reference https://github.com/modelcontextprotocol/modelcontextprotocol/tree/main/schema which contains versioned schemas in JSON (schema.json) and TypeScript (schema.ts) formats."