Add workflow to block sponsor asset changes

Author: mattstratton

.github/workflows/no-sponsors-changes.yml

@@ -0,0 +1,91 @@
+name: Block sponsor asset changes
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened, ready_for_review]
+
+permissions:
+  contents: read
+  pull-requests: write
+
+jobs:
+  guard:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Detect changes under static/img/sponsors
+        id: changes
+        uses: dorny/paths-filter@v3
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          list-files: json
+          filters: |
+            sponsors:
+              - 'static/img/sponsors/**'
+
+      # This step will:
+      # 1) Add a single comment (once per PR) listing the files
+      # 2) Fail the check whenever changes are detected (even if comment already exists)
+      - name: Comment and fail if sponsors directory changed
+        if: steps.changes.outputs.sponsors == 'true'
+        uses: actions/github-script@v7
+        env:
+          SPONSORS_FILES_JSON: ${{ steps.changes.outputs.sponsors_files }}
+        with:
+          script: |
+            const owner = context.repo.owner;
+            const repo = context.repo.repo;
+            const issue_number = context.payload.pull_request.number;
+
+            const marker = "<!-- sponsors-dir-guard -->";
+
+            // Parse the changed files list from dorny/paths-filter output
+            let files = [];
+            try {
+              files = JSON.parse(process.env.SPONSORS_FILES_JSON || "[]");
+            } catch (e) {
+              files = [];
+            }
+
+            const fileList = files.length
+              ? files.map(f => `- \`${f}\``).join("\n")
+              : "- _(Unable to enumerate files, but changes were detected)_";
+
+            // Check if we already commented
+            const comments = await github.paginate(github.rest.issues.listComments, {
+              owner,
+              repo,
+              issue_number,
+              per_page: 100,
+            });
+
+            const alreadyCommented = comments.some(c => (c.body || "").includes(marker));
+
+            if (!alreadyCommented) {
+              const body = [
+                "🚫 **Blocked: sponsor assets directory change detected**",
+                "",
+                "This PR adds or modifies files under `static/img/sponsors/`.",
+                "",
+                "**These files should not be added or changed.**",
+                "",
+                "Please use the `assets/sponsors/*` directory instead."
+                "",
+                "**Affected files:**",
+                fileList,
+                "",
+                marker
+              ].join("\n");
+
+              await github.rest.issues.createComment({
+                owner,
+                repo,
+                issue_number,
+                body,
+              });
+            } else {
+              core.info("Sponsor directory warning comment already exists; skipping comment creation.");
+            }
+
+            // Always fail the check if files in this directory were touched
+            core.setFailed("Changes detected under static/img/sponsors/. Revert these changes to pass.");