Drop the service worker warm-up now that listeners register in time

document_start pinged the worker with { contentScriptQuery: 'warmup' } so
it would be awake by the time document_end connected. Nothing ever
handled that message - there is no listener for it anywhere - so it always
rejected and the rejection was swallowed. Booting the worker was the whole
point.

That was a workaround for listeners registering after an await, which is
fixed: every backend now registers during the worker's initial
synchronous run, so the connection that wakes it is routed rather than
dropped. The warm-up no longer has a job.

Measured against a worker left idle for 60s, twice, with the warm-up gone:
the theme still applies pre-paint, stored preview marks come back 252-253ms
after load, and a preview click writes through and persists. Both the read
and write paths survive a cold wake with nothing pre-booting the worker.

Refs #301

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: sabjorn

src/document_start.ts

@@ -2,12 +2,6 @@ import { createLogger } from './logger';
 
 const log = createLogger();
 
-const warmServiceWorker = (): void => {
-  chrome.runtime
-    .sendMessage({ contentScriptQuery: 'warmup' })
-    .catch(() => log.debug('Warm-up message went unanswered; the worker still booted'));
-};
-
 const captureUrlCartParam = (): void => {
   if (!window.location.search.includes('bes_cart')) return;
 
@@ -30,5 +24,4 @@ const captureUrlCartParam = (): void => {
   window.location.replace(newUrl);
 };
 
-warmServiceWorker();
 captureUrlCartParam();

test/document_start.test.ts

@@ -35,23 +35,17 @@ const runDocumentStart = async () => {
   await import('../src/document_start');
 };
 
-describe('document_start service worker warm-up', () => {
+describe('document_start service worker messaging', () => {
   beforeEach(() => {
     mockSendMessage.mockClear();
   });
 
-  it('pings the service worker so it boots ahead of document_end', async () => {
+  it('does not message the service worker, so nothing depends on it being awake', async () => {
     setLocation('');
 
     await runDocumentStart();
 
-    expect(mockSendMessage).toHaveBeenCalledWith({ contentScriptQuery: 'warmup' });
-  });
-
-  it('survives the ping going unanswered', async () => {
-    setLocation('');
-
-    await expect(runDocumentStart()).resolves.not.toThrow();
+    expect(mockSendMessage).not.toHaveBeenCalled();
   });
 });