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();
+  });
+});

webui/vite.config.ts

@@ -2,6 +2,36 @@ import { defineConfig, loadEnv } from "vite";
 import react from "@vitejs/plugin-react";
 import path from "node:path";
 
+export function webuiManualChunk(id: string): string | undefined {
+  if (id.includes("node_modules/refractor/lang/")) {
+    return;
+  }
+  // Refractor reaches this HAST helper through hastscript. Keeping it with
+  // Refractor prevents syntax-highlight <-> markdown-vendor circular chunks.
+  if (
+    id.includes("node_modules/react-syntax-highlighter")
+    || id.includes("node_modules/refractor/core")
+    || id.includes("node_modules/hast-util-parse-selector")
+  ) {
+    return "syntax-highlight";
+  }
+  if (
+    id.includes("node_modules/react-markdown")
+    || id.includes("node_modules/remark-")
+    || id.includes("node_modules/rehype-")
+    || id.includes("node_modules/unified")
+    || id.includes("node_modules/mdast-")
+    || id.includes("node_modules/hast-")
+    || id.includes("node_modules/micromark")
+    || id.includes("node_modules/unist-")
+  ) {
+    return "markdown-vendor";
+  }
+  if (id.includes("node_modules/katex")) {
+    return "katex";
+  }
+}
+
 export default defineConfig(({ mode }) => {
   const env = loadEnv(mode, process.cwd(), "");
   const target = env.NANOBOT_API_URL ?? "http://127.0.0.1:8765";
@@ -32,32 +62,7 @@ export default defineConfig(({ mode }) => {
       sourcemap: false,
       rollupOptions: {
         output: {
-          manualChunks(id) {
-            if (id.includes("node_modules/refractor/lang/")) {
-              return;
-            }
-            if (
-              id.includes("node_modules/react-syntax-highlighter")
-              || id.includes("node_modules/refractor/core")
-            ) {
-              return "syntax-highlight";
-            }
-            if (
-              id.includes("node_modules/react-markdown")
-              || id.includes("node_modules/remark-")
-              || id.includes("node_modules/rehype-")
-              || id.includes("node_modules/unified")
-              || id.includes("node_modules/mdast-")
-              || id.includes("node_modules/hast-")
-              || id.includes("node_modules/micromark")
-              || id.includes("node_modules/unist-")
-            ) {
-              return "markdown-vendor";
-            }
-            if (id.includes("node_modules/katex")) {
-              return "katex";
-            }
-          },
+          manualChunks: webuiManualChunk,
         },
       },
     },