ci: skip pytest smoke on documentation-only changes (#2768)

* ci: skip pytest smoke on documentation-only changes

Adding paths-ignore for **.md and docs/** so that PRs that touch only
markdown files do not trigger the full pytest suite. Runner minutes are
spent only when Python or config files change.

Closes #2646.

* ci: detect docs-only changes inside the job instead of paths-ignore

Previously paths-ignore on the pull_request trigger caused the entire
workflow to be skipped, which can leave required checks pending and block
merging. Instead, keep the workflow always-triggered and detect docs-only
changes inside python-tests with a git diff step; if every changed file
is a .md or docs/ path, the step reports success without running pytest.

The syntax jobs (python-syntax, node-syntax) are cheap enough to always run.

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

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -51,10 +51,39 @@ jobs:
     continue-on-error: true
     steps:
       - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5  # v4
+        with:
+          fetch-depth: 0
+
+      # Detect whether this PR only touches documentation files.
+      # If so, skip the expensive pytest run while still reporting a passing check.
+      - name: Check for docs-only changes
+        id: docs-check
+        run: |
+          if [ "${{ github.event_name }}" = "pull_request" ]; then
+            BASE="${{ github.event.pull_request.base.sha }}"
+            HEAD="${{ github.event.pull_request.head.sha }}"
+          else
+            BASE="${{ github.event.before }}"
+            HEAD="${{ github.sha }}"
+          fi
+          # List all changed files; if every file matches docs/markdown patterns, skip pytest.
+          changed=$(git diff --name-only "$BASE" "$HEAD" 2>/dev/null || git diff --name-only HEAD~1 HEAD)
+          non_docs=$(echo "$changed" | grep -Ev '^(docs/|.*\.md$|\.github/[^/]+\.md$)' || true)
+          if [ -z "$non_docs" ]; then
+            echo "docs_only=true" >> "$GITHUB_OUTPUT"
+            echo "Docs-only change detected — skipping pytest."
+          else
+            echo "docs_only=false" >> "$GITHUB_OUTPUT"
+          fi
+
       - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065  # v5
+        if: steps.docs-check.outputs.docs_only != 'true'
         with:
           python-version: "3.11"
           cache: pip
       - run: pip install -r requirements.txt
+        if: steps.docs-check.outputs.docs_only != 'true'
       - run: mkdir -p data  # sqlite DB lives at ./data/app.db
+        if: steps.docs-check.outputs.docs_only != 'true'
       - run: python -m pytest -q
+        if: steps.docs-check.outputs.docs_only != 'true'