claude-review/action.yml

name: Claude Code Review
description: >
  Reviews pull requests using Claude AI. Reads review instructions from a
  prompt file in the target branch and posts the result as a PR comment.
author: mars3142

inputs:
  api_key:
    description: Anthropic API key
    required: true
  gitea_token:
    description: Gitea token for posting PR comments
    required: true
  prompt_file:
    description: Path to the review prompt file inside the target branch
    required: false
    default: .claude/review-prompt.md
  model:
    description: Claude model ID
    required: false
    default: claude-sonnet-4-6

runs:
  using: composite
  steps:
    - name: Checkout repository
      uses: actions/checkout@v4
      with:
        fetch-depth: 0

    - name: Fetch PR branches
      shell: bash
      run: |
        git fetch origin "${{ github.base_ref }}"
        git fetch origin "${{ github.head_ref }}" 2>/dev/null || \
          git fetch origin \
            "refs/pull/${{ github.event.pull_request.number }}/head:pr/${{ github.event.pull_request.number }}"

    - name: Read prompt file from target branch
      shell: bash
      run: |
        PROMPT_FILE="${{ inputs.prompt_file }}"

        if ! git show "origin/${{ github.base_ref }}:${PROMPT_FILE}" \
              > /tmp/claude-review-prompt.txt 2>/dev/null; then
          echo "::error::Prompt file '${PROMPT_FILE}' not found in branch '${{ github.base_ref }}'"
          exit 1
        fi

        echo "Prompt loaded from '${PROMPT_FILE}' ($(wc -c < /tmp/claude-review-prompt.txt) bytes)"

    - name: Generate PR diff
      shell: bash
      run: |
        HEAD_REF="${{ github.head_ref }}"
        BASE_REF="origin/${{ github.base_ref }}"

        if git diff "${BASE_REF}...origin/${HEAD_REF}" \
              > /tmp/claude-review-diff.txt 2>/dev/null; then
          true
        else
          git diff "${BASE_REF}" \
            "pr/${{ github.event.pull_request.number }}" \
            > /tmp/claude-review-diff.txt
        fi

        DIFF_SIZE=$(wc -c < /tmp/claude-review-diff.txt)

        if [ "$DIFF_SIZE" -eq 0 ]; then
          echo "::notice::Empty diff — skipping review"
          echo "CLAUDE_SKIP=true" >> "$GITHUB_ENV"
          exit 0
        fi

        # Truncate at 80 KB to stay within API limits
        if [ "$DIFF_SIZE" -gt 81920 ]; then
          head -c 81920 /tmp/claude-review-diff.txt > /tmp/claude-review-diff-trunc.txt
          printf '\n\n[... diff truncated at 80 KB ...]\n' >> /tmp/claude-review-diff-trunc.txt
          mv /tmp/claude-review-diff-trunc.txt /tmp/claude-review-diff.txt
          echo "::warning::Diff truncated to 80 KB"
        fi

        echo "Diff ready ($(wc -c < /tmp/claude-review-diff.txt) bytes)"

    - name: Call Claude API
      if: env.CLAUDE_SKIP != 'true'
      shell: bash
      env:
        CLAUDE_API_KEY: ${{ inputs.api_key }}
      run: |
        jq -n \
          --arg model  "${{ inputs.model }}" \
          --arg prompt "$(cat /tmp/claude-review-prompt.txt)" \
          --arg diff   "$(cat /tmp/claude-review-diff.txt)" \
          '{
            model: $model,
            max_tokens: 4096,
            messages: [{
              role: "user",
              content: ($prompt + "\n\n---\n\n## Pull Request Diff\n\n```diff\n" + $diff + "\n```")
            }]
          }' > /tmp/claude-review-request.json

        HTTP_STATUS=$(curl -s -w "%{http_code}" -o /tmp/claude-review-response.json \
          -X POST "https://api.anthropic.com/v1/messages" \
          -H "x-api-key: ${CLAUDE_API_KEY}" \
          -H "anthropic-version: 2023-06-01" \
          -H "content-type: application/json" \
          -d @/tmp/claude-review-request.json)

        if [ "$HTTP_STATUS" -ne 200 ]; then
          echo "::error::Claude API returned HTTP ${HTTP_STATUS}"
          jq -r '.error.message // .' /tmp/claude-review-response.json
          exit 1
        fi

        REVIEW=$(jq -r '.content[0].text' /tmp/claude-review-response.json)

        if [ -z "$REVIEW" ] || [ "$REVIEW" = "null" ]; then
          echo "::error::Empty response from Claude API"
          cat /tmp/claude-review-response.json
          exit 1
        fi

        printf '%s' "$REVIEW" > /tmp/claude-review-result.txt
        echo "Review ready ($(wc -c < /tmp/claude-review-result.txt) bytes)"

    - name: Post review comment
      if: env.CLAUDE_SKIP != 'true'
      shell: bash
      env:
        GITEA_TOKEN: ${{ inputs.gitea_token }}
      run: |
        jq -n \
          --arg review "$(cat /tmp/claude-review-result.txt)" \
          --arg model  "${{ inputs.model }}" \
          '{body: ("## Claude Code Review\n\n" + $review + "\n\n---\n*Review generated by `" + $model + "`*")}' \
          > /tmp/claude-review-comment.json

        HTTP_STATUS=$(curl -s -w "%{http_code}" -o /tmp/claude-review-comment-response.json \
          -X POST \
          "${{ github.server_url }}/api/v1/repos/${{ github.repository }}/issues/${{ github.event.pull_request.number }}/comments" \
          -H "Authorization: token ${GITEA_TOKEN}" \
          -H "Content-Type: application/json" \
          -d @/tmp/claude-review-comment.json)

        if [ "$HTTP_STATUS" -ne 201 ]; then
          echo "::error::Failed to post comment (HTTP ${HTTP_STATUS})"
          cat /tmp/claude-review-comment-response.json
          exit 1
        fi

        echo "Review posted to PR #${{ github.event.pull_request.number }}"