perf: accelerate production request hot paths

packages/dev-server/test/production-hmr.test.ts

@@ -1,4 +1,7 @@
 import { expect, test } from "bun:test";
+import { mkdtempSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
 import { createProductionHandlers, type ProdManifest } from "../src/prod.ts";
 
 const manifest: ProdManifest = {
@@ -72,3 +75,49 @@ test("production client-load endpoint returns only the requested named result",
   expect(response.headers.get("cache-control")).toBe("private, no-store");
   expect(await response.json()).toEqual({ data: [{ id: 1, name: "Ada" }] });
 });
+
+test("production prefers fast gzip for dynamic HTML and cached Brotli for immutable assets", async () => {
+  const largeManifest: ProdManifest = {
+    ...manifest,
+    pages: [
+      {
+        raw: "/large",
+        mod: { default: () => `<main>${"fast production ".repeat(500)}</main>` },
+      },
+    ],
+  };
+  const directory = mkdtempSync(join(tmpdir(), "wrnexus-prod-assets-"));
+  const assetPath = join(directory, "app.js");
+  writeFileSync(assetPath, "const production = true;\n".repeat(500));
+  const handlers = createProductionHandlers(largeManifest, {
+    pluginAssets: {
+      "/assets/app.js": {
+        path: assetPath,
+        contentType: "text/javascript; charset=utf-8",
+      },
+    },
+  });
+  const headers = { "accept-encoding": "br, gzip" };
+  const page = (await handlers.fetch(
+    new Request("http://localhost/large", { headers }),
+    server,
+  )) as Response;
+  expect(page.headers.get("content-encoding")).toBe("gzip");
+
+  const firstAsset = (await handlers.fetch(
+    new Request("http://localhost/assets/app.js", { headers }),
+    server,
+  )) as Response;
+  const secondAsset = (await handlers.fetch(
+    new Request("http://localhost/assets/app.js", { headers }),
+    server,
+  )) as Response;
+  expect(firstAsset.headers.get("content-encoding")).toBe("br");
+  expect(await secondAsset.arrayBuffer()).toEqual(await firstAsset.arrayBuffer());
+
+  const head = (await handlers.fetch(
+    new Request("http://localhost/assets/app.js", { method: "HEAD", headers }),
+    server,
+  )) as Response;
+  expect(head.headers.get("content-encoding")).toBeNull();
+});