Fix Vale CI to parse space-separated file list correctly

Add separator: " " to the vale-action step so it correctly parses the
space-separated file list instead of falling back to scanning the entire
repo.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: ctauchen

.github/workflows/vale.yml

@@ -7,22 +7,46 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+      - name: Get changed files
+        id: changed
+        run: |
+          FILES=$(git diff --name-only --diff-filter=d ${{ github.event.pull_request.base.sha }}...${{ github.event.pull_request.head.sha }} -- '*.md' '*.mdx')
+          if [ -z "$FILES" ]; then
+            echo "skip=true" >> "$GITHUB_OUTPUT"
+            echo 'files=all' >> "$GITHUB_OUTPUT"
+          else
+            echo "skip=false" >> "$GITHUB_OUTPUT"
+            JSON=$(echo "$FILES" | jq -R -s -c 'split("\n") | map(select(. != ""))')
+            echo "files=$JSON" >> "$GITHUB_OUTPUT"
+          fi
       - name: Enable Corepack
+        if: steps.changed.outputs.skip == 'false'
         run: corepack enable
       - name: Setup Node.js with Yarn
+        if: steps.changed.outputs.skip == 'false'
         uses: actions/setup-node@v6
         with:
           node-version: '22'
           cache: yarn
       - name: Install dependencies
+        if: steps.changed.outputs.skip == 'false'
         run: yarn install --immutable
       - name: Install mdx2vast globally
+        if: steps.changed.outputs.skip == 'false'
         run: npm install -g mdx2vast
       - name: Swap stuff
+        if: steps.changed.outputs.skip == 'false'
         run: |
           sudo apt-get install ripgrep
-          rg -l0 '\$\[[^\]]*\]' -g '*.mdx' -g '*.md' . | xargs -0 perl -i -pe 's/\$\[[^\]]*\]/PICKLEVAR/g'
+          FILES=$(echo '${{ steps.changed.outputs.files }}' | jq -r '.[]' | tr '\n' ' ')
+          if [ -n "$FILES" ]; then
+            rg -l0 '\$\[[^\]]*\]' -- $FILES | xargs -0 perl -i -pe 's/\$\[[^\]]*\]/PICKLEVAR/g' || true
+          fi
       - name: Run Vale with Reviewdog
+        if: steps.changed.outputs.skip == 'false'
         uses: errata-ai/vale-action@reviewdog
         with:
+          files: ${{ steps.changed.outputs.files }}
           fail_on_error: false