fix(cli): installing Chrome on a busy Windows PC no longer takes ten minutes

packages/cli/src/renderSetupWorker.priority.test.ts

@@ -7,6 +7,9 @@ vi.mock("node:os", async (importOriginal) => ({
   setPriority: os.setPriority,
 }));
 vi.mock("./utils/lintProject.js", () => ({ lintProject: vi.fn(async () => ({ ok: true })) }));
+vi.mock("./browser/installRun.js", () => ({
+  runBrowserInstall: vi.fn(async () => ({ ok: true })),
+}));
 
 beforeEach(() => {
   vi.resetModules();
@@ -39,6 +42,33 @@ it("a render's lint keeps normal priority", async () => {
   expect(write).toHaveBeenCalledWith(expect.stringContaining('{"ok":true}'));
 });
 
+// fails without the fix: at normal priority, each write of the download queues behind a busy PC's work.
+it("the Chrome install runs one step above normal priority", async () => {
+  process.argv[2] = "browser-install";
+  process.env.HYPERFRAMES_RENDER_SETUP_INPUT = "{}";
+  const write = vi.spyOn(process.stdout, "write").mockImplementation(() => true);
+
+  await import("./renderSetupWorker.js");
+
+  expect(os.setPriority).toHaveBeenCalledWith(constants.priority.PRIORITY_ABOVE_NORMAL);
+  expect(write).toHaveBeenCalledWith(expect.stringContaining('{"ok":true}'));
+});
+
+it("the Chrome install still runs when the system refuses the higher priority", async () => {
+  process.argv[2] = "browser-install";
+  process.env.HYPERFRAMES_RENDER_SETUP_INPUT = "{}";
+  os.setPriority.mockImplementation(() => {
+    throw nodeSystemErrorWithOsCodeInInfo("EACCES");
+  });
+  const write = vi.spyOn(process.stdout, "write").mockImplementation(() => true);
+  const warn = vi.spyOn(process.stderr, "write").mockImplementation(() => true);
+
+  await import("./renderSetupWorker.js");
+
+  expect(write).toHaveBeenCalledWith(expect.stringContaining('{"ok":true}'));
+  expect(warn).not.toHaveBeenCalled();
+});
+
 const nodeSystemErrorWithOsCodeInInfo = (code: string) =>
   Object.assign(new Error(`A system error occurred: uv_os_setpriority returned ${code}`), {
     code: "ERR_SYSTEM_ERROR",

packages/cli/src/renderSetupWorker.ts

@@ -22,22 +22,25 @@ const disposeSignalHandlers = installRenderSetupSignalHandlers(
 
 const SANDBOX_REFUSED_PRIORITY = new Set(["EPERM", "EACCES"]);
 
-function lowerPriority(): void {
+function setOwnPriority(priority: number, whatStaysNormal: string): void {
   try {
-    setPriority(constants.priority.PRIORITY_LOW);
+    setPriority(priority);
   } catch (error) {
     if (SANDBOX_REFUSED_PRIORITY.has((error as { info?: { code?: string } }).info?.code ?? ""))
       return;
-    process.stderr.write(`Lint runs at normal priority: ${(error as Error).message}\n`);
+    process.stderr.write(`${whatStaysNormal} at normal priority: ${(error as Error).message}\n`);
   }
 }
 
 async function runMode(): Promise<unknown> {
   if (mode === "browser") return ensureBrowser(input);
-  if (mode === "browser-install") return runBrowserInstall(input);
+  if (mode === "browser-install") {
+    setOwnPriority(constants.priority.PRIORITY_ABOVE_NORMAL, "The Chrome install runs");
+    return runBrowserInstall(input);
+  }
   if (mode === "lint") {
     // A background lint (Studio's, preview's) takes idle CPU only; a render waits on its lint, so that one does not.
-    if (input.background) lowerPriority();
+    if (input.background) setOwnPriority(constants.priority.PRIORITY_LOW, "Lint runs");
     return lintProject(
       input.projectDir,
       input.entryFile,