Fix link check

.github/workflows/link_checker_report.yaml

@@ -14,6 +14,7 @@
 name: Link Checks
 
 on:
+  pull_request:
   schedule:
     - cron: '0 0 * * 1'
 jobs:

.github/workflows/lk.yml

@@ -0,0 +1,132 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+name: Link Checker
+
+
+on:
+  pull_request:
+permissions:
+  contents: read
+  pull-requests: write
+  issues: write
+
+jobs:
+
+  link-check:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+        with:
+          fetch-depth: 0
+
+      - name: Identify Changed Files
+        id: changed-files
+        shell: bash
+        run: |
+          git fetch origin main
+          CHANGED_FILES=$(git diff --name-only --diff-filter=ACMRT origin/main...HEAD -- '*.md')
+
+          if [ -z "$CHANGED_FILES" ]; then
+            echo "No markdown files changed. Skipping checks."
+            echo "HAS_CHANGES=false" >> "$GITHUB_OUTPUT"
+          else
+            echo "--- Changed Files to Scan ---"
+            echo "$CHANGED_FILES"
+            echo "-----------------------------"
+
+            FILES_QUOTED=$(echo "$CHANGED_FILES" | sed 's/^/"/;s/$/"/' | tr '\n' ' ')
+
+            # Use EOF to write multiline or long strings to GITHUB_OUTPUT
+            echo "HAS_CHANGES=true" >> "$GITHUB_OUTPUT"
+            echo "CHECK_FILES<<EOF" >> "$GITHUB_OUTPUT"
+            echo "$FILES_QUOTED" >> "$GITHUB_OUTPUT"
+            echo "EOF" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Restore lychee cache
+        if: steps.changed-files.outputs.HAS_CHANGES == 'true'
+        uses: actions/cache@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5
+        with:
+          path: .lycheecache
+          key: cache-lychee-${{ github.sha }}
+          restore-keys: cache-lychee-
+
+      - name: Link Checker
+        id: lychee-check       
+        if: steps.changed-files.outputs.HAS_CHANGES == 'true'
+        uses: lycheeverse/lychee-action@a8c4c7cb88f0c7386610c35eb25108e448569cb0 # v2
+        continue-on-error: true 
+        with:
+          args: >
+            --quiet
+            --no-progress
+            --cache
+            --max-cache-age 1d
+            --exclude '^neo4j\+.*' --exclude '^bolt://.*'
+            ${{ steps.changed-files.outputs.CHECK_FILES }}
+          output: lychee-report.md
+          format: markdown
+          fail: true           
+          jobSummary: false    
+          debug: false
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Find comment
+        uses: peter-evans/find-comment@b30e6a3c0ed37e7c023ccd3f1db5c6c0b0c23aad # v4
+        id: find-comment
+        with:
+          issue-number: ${{ github.event.pull_request.number }}
+          comment-author: 'github-actions[bot]'
+          body-includes: "## Link Resolution Note"
+
+      - name: Delete comment on success
+        if: steps.lychee-check.outcome == 'success' && steps.find-comment.outputs.comment-id != ''
+        run: |
+          gh api \
+            --method DELETE \
+            -H "Accept: application/vnd.github+json" \
+            /repos/${{ github.repository }}/issues/comments/${STEPS_FIND_COMMENT_OUTPUTS_COMMENT_ID}
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          STEPS_FIND_COMMENT_OUTPUTS_COMMENT_ID: ${{ steps.find-comment.outputs.comment-id }}
+
+      - name: Prepare Report 
+        if: steps.changed-files.outputs.HAS_CHANGES == 'true' && steps.lychee-check.outcome == 'failure'
+        run: |
+          echo "## Link Resolution Note" > full-report.md
+          echo "Local links and directory changes work differently on GitHub than on the docsite. You must ensure fixes pass the **GitHub check** and also work with **\`hugo server\`**." >> full-report.md
+          echo "See [Link Checking and Fixing with Lychee](https://github.com/googleapis/genai-toolbox/blob/main/DEVELOPER.md#link-checking-and-fixing-with-lychee) for more details." >> full-report.md          
+          echo "" >> full-report.md 
+          sed -E '/(Redirect|Redirects per input)/d' lychee-report.md >> full-report.md
+
+      - name: Create PR Comment
+        if: steps.changed-files.outputs.HAS_CHANGES == 'true' && steps.lychee-check.outcome == 'failure'
+        uses: peter-evans/create-or-update-comment@e8674b075228eee787fea43ef493e45ece1004c9 # v5
+        with:
+          comment-id: ${{ steps.find-comment.outputs.comment-id }}
+          issue-number: ${{ github.event.pull_request.number }}
+          body-path: full-report.md
+          edit-mode: replace
+
+      - name: Display Failure Report
+        # Run this ONLY if the link checker failed
+        if: steps.lychee-check.outcome == 'failure'
+        run: |
+          # We can now simply output the prepared file to the job summary
+          cat full-report.md >> $GITHUB_STEP_SUMMARY
+
+          # Fail the job
+          exit 1