fix(webui): keep syntax highlighting chunks acyclic

webui/src/tests/diff-syntax-highlight.integration.test.tsx

@@ -43,9 +43,11 @@ describe("DiffSyntaxHighlight with Prism", () => {
     const highlighted = await screen.findByTestId("syntax-highlighted-diff-hunk");
     await waitFor(
       () => {
-        expect(highlighted.querySelectorAll('td:last-child span[style*="color"]')).not.toHaveLength(
-          0,
+        const tokens = highlighted.querySelectorAll<HTMLElement>(
+          'td:last-child span[style*="color"]',
         );
+        expect(tokens).not.toHaveLength(0);
+        expect(new Set([...tokens].map((token) => token.style.color)).size).toBeGreaterThan(1);
       },
       { timeout: 10_000 },
     );

webui/src/tests/vite-config.test.ts

@@ -0,0 +1,21 @@
+import { describe, expect, it } from "vitest";
+
+import { webuiManualChunk } from "../../vite.config";
+
+describe("webuiManualChunk", () => {
+  it("keeps Refractor's selector parser in the syntax highlighting chunk", () => {
+    expect(
+      webuiManualChunk("/repo/node_modules/hast-util-parse-selector/index.js"),
+    ).toBe("syntax-highlight");
+  });
+
+  it("keeps markdown-only hast utilities in the markdown chunk", () => {
+    expect(
+      webuiManualChunk("/repo/node_modules/hast-util-to-jsx-runtime/lib/index.js"),
+    ).toBe("markdown-vendor");
+  });
+
+  it("leaves language grammars as independently loaded chunks", () => {
+    expect(webuiManualChunk("/repo/node_modules/refractor/lang/python.js")).toBeUndefined();
+  });
+});