Evals: PR Guidance adding workflow (#23164)

.github/workflows/eval-guidance.yml

@@ -0,0 +1,69 @@
+name: 'Evals: PR Guidance'
+
+on:
+  pull_request:
+    paths:
+      - 'packages/core/src/**/*.ts'
+      - '!**/*.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@08eba0b27e820071cde6df949e0beb9ba4906955' # ratchet:actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: 'Set up Node.js'
+        uses: 'actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020' # ratchet:actions/setup-node@v4.4.0
+        with:
+          node-version-file: '.nvmrc'
+          cache: 'npm'
+
+      - name: 'Detect Steering Changes'
+        id: 'detect'
+        run: |
+          STEERING_DETECTED=$(node scripts/changed_prompt.js --steering-only)
+          echo "STEERING_DETECTED=$STEERING_DETECTED" >> "$GITHUB_OUTPUT"
+
+      - name: 'Analyze PR Content'
+        if: "steps.detect.outputs.STEERING_DETECTED == 'true'"
+        id: 'analysis'
+        env:
+          GH_TOKEN: '${{ 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@65f9e5c9a1f2cd378bd74b2e057c9736982a8e74' # ratchet:thollander/actions-comment-pull-request@v3
+        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.*

scripts/changed_prompt.js

@@ -5,14 +5,26 @@
  */
 import { execSync } from 'node:child_process';
 
-const EVALS_FILE_PREFIXES = [
+const CORE_STEERING_PATHS = [
   'packages/core/src/prompts/',
   'packages/core/src/tools/',
-  'evals/',
+];
+
+const TEST_PATHS = ['evals/'];
+
+const STEERING_SIGNATURES = [
+  'LocalAgentDefinition',
+  'LocalInvocation',
+  'ToolDefinition',
+  'inputSchema',
+  "kind: 'local'",
 ];
 
 function main() {
   const targetBranch = process.env.GITHUB_BASE_REF || 'main';
+  const verbose = process.argv.includes('--verbose');
+  const steeringOnly = process.argv.includes('--steering-only');
+
   try {
     const remoteUrl = process.env.GITHUB_REPOSITORY
       ? `https://github.com/${process.env.GITHUB_REPOSITORY}.git`
@@ -30,18 +42,60 @@ function main() {
       .split('\n')
       .filter(Boolean);
 
-    const shouldRun = changedFiles.some((file) =>
+    let detected = false;
-      EVALS_FILE_PREFIXES.some((prefix) => file.startsWith(prefix)),
+    const reasons = [];
-    );
 
-    console.log(shouldRun ? 'true' : 'false');
+    // 1. Path-based detection
+    for (const file of changedFiles) {
+      if (CORE_STEERING_PATHS.some((prefix) => file.startsWith(prefix))) {
+        detected = true;
+        reasons.push(`Matched core steering path: ${file}`);
+        if (!verbose) break;
+      }
+      if (
+        !steeringOnly &&
+        TEST_PATHS.some((prefix) => file.startsWith(prefix))
+      ) {
+        detected = true;
+        reasons.push(`Matched test path: ${file}`);
+        if (!verbose) break;
+      }
+    }
+
+    // 2. Signature-based detection (only in packages/core/src/ and only if not already detected or if verbose)
+    if (!detected || verbose) {
+      const coreChanges = changedFiles.filter((f) =>
+        f.startsWith('packages/core/src/'),
+      );
+      if (coreChanges.length > 0) {
+        // Get the actual diff content for core files
+        const diff = execSync(
+          `git diff -U0 FETCH_HEAD...HEAD -- packages/core/src/`,
+          { encoding: 'utf-8' },
+        );
+        for (const sig of STEERING_SIGNATURES) {
+          if (diff.includes(sig)) {
+            detected = true;
+            reasons.push(`Matched steering signature in core: ${sig}`);
+            if (!verbose) break;
+          }
+        }
+      }
+    }
+
+    if (verbose && reasons.length > 0) {
+      process.stderr.write('Detection reasons:\n');
+      reasons.forEach((r) => process.stderr.write(` - ${r}\n`));
+    }
+
+    process.stdout.write(detected ? 'true' : 'false');
   } catch (error) {
-    // If anything fails (e.g., no git history), run evals to be safe
+    // If anything fails (e.g., no git history), run evals/guidance to be safe
-    console.warn(
+    process.stderr.write(
-      'Warning: Failed to determine if evals should run. Defaulting to true.',
+      'Warning: Failed to determine if changes occurred. Defaulting to true.\n',
     );
-    console.error(error);
+    process.stderr.write(String(error) + '\n');
-    console.log('true');
+    process.stdout.write('true');
   }
 }