name: 'Evals: PR Guidance'

on:
  pull_request:
    paths:
      - 'packages/core/src/**/*.ts'
      - '.gemini/commands/*.toml'
      - '.gemini/skills/**/SKILL.md'
      - '!**/*.test.ts'
      - '!**/*.test.tsx'

permissions:
  pull-requests: 'write'
  contents: 'read'

jobs:
  provide-guidance:
    name: 'Model Steering Guidance'
    runs-on: 'ubuntu-latest'
    if: "github.repository == 'google-gemini/gemini-cli'"
    steps:
      - name: 'Checkout'
        uses: 'actions/checkout@v4'
        with:
          fetch-depth: 0

      - name: 'Detect Steering Changes'
        id: 'detect'
        env:
          GH_TOKEN: '${{ secrets.GITHUB_TOKEN }}'
        run: |
          # 1. Path-based detection (The "Knowns")
          KNOWN_PATHS=("packages/core/src/prompts/snippets" "packages/core/src/tools/definitions" ".gemini/commands" ".gemini/skills")
          PR_FILES=$(git diff --name-only origin/${{ github.base_ref }}...HEAD)

          IS_STEERING_CHANGE=false
          for path in "${KNOWN_PATHS[@]}"; do
            if echo "$PR_FILES" | grep -q "$path"; then
              IS_STEERING_CHANGE=true
              break
            fi
          done

          # 2. Signature-based detection (The "Unknowns")
          # We look for patterns that define tools or agents in any file
          SIGNATURES=("LocalAgentDefinition" "LocalInvocation" "ToolDefinition" "inputSchema" "kind: 'local'")
          if [ "$IS_STEERING_CHANGE" = false ]; then
            PR_DIFF=$(git diff -U0 origin/${{ github.base_ref }}...HEAD)
            for sig in "${SIGNATURES[@]}"; do
              if echo "$PR_DIFF" | grep -q "$sig"; then
                IS_STEERING_CHANGE=true
                echo "DEBUG: Detected steering via signature: $sig"
                break
              fi
            done
          fi

          echo "STEERING_DETECTED=$IS_STEERING_CHANGE" >> "$GITHUB_OUTPUT"

      - name: 'Analyze PR Content'
        if: "steps.detect.outputs.STEERING_DETECTED == 'true'"
        id: 'analysis'
        env:
          GH_TOKEN: '${{ secrets.GITHUB_TOKEN }}'
        run: |
          # Check for behavioral eval changes
          EVAL_CHANGES=$(git diff --name-only origin/${{ github.base_ref }}...HEAD | grep "^evals/" || true)
          if [ -z "$EVAL_CHANGES" ]; then
            echo "MISSING_EVALS=true" >> "$GITHUB_OUTPUT"
          fi

          # Check if user is a maintainer (has write/admin access)
          USER_PERMISSION=$(gh api repos/${{ github.repository }}/collaborators/${{ github.actor }}/permission --jq '.permission')
          if [[ "$USER_PERMISSION" == "admin" || "$USER_PERMISSION" == "write" ]]; then
            echo "IS_MAINTAINER=true" >> "$GITHUB_OUTPUT"
          fi

      - name: 'Post Guidance Comment'
        if: "steps.detect.outputs.STEERING_DETECTED == 'true'"
        uses: 'thollander/actions-comment-pull-request@v2'
        with:
          comment_tag: 'eval-guidance-bot'
          message: |
            ### 🧠 Model Steering Guidance

            This PR modifies files that affect the model's behavior (prompts, tools, or instructions).

            ${{ steps.analysis.outputs.MISSING_EVALS == 'true' && '- ⚠️ **Consider adding Evals:** No behavioral evaluations (`evals/*.eval.ts`) were added or updated in this PR. Consider adding a test case to verify the new behavior and prevent regressions.' || '' }}
            ${{ steps.analysis.outputs.IS_MAINTAINER == 'true' && '- 🚀 **Maintainer Reminder:** Please ensure that these changes do not regress results on benchmark evals before merging.' || '' }}

            ---
            *This is an automated guidance message triggered by steering logic signatures.*