web: the offer to install is made once, and the answer is kept

docker/frontend/scripts/pwa-check.mjs

@@ -1,7 +1,7 @@
 // Install support is not visible in the source. It is the manifest the browser
 // reads, the worker it registers, and what that worker still holds once the network
 // is gone — so unlike the other checks here, which read a module and assert on it,
-// this one has to drive a real browser at a real build. Four assertions, one line
+// this one has to drive a real browser at a real build. Five assertions, one line
 // each, against a preview server:
 //
 //   npx vite build && npx vite preview --port 4183 &
@@ -25,7 +25,7 @@ const browser = await chromium.launch({
 });
 const context = await browser.newContext();
 
-// Every assertion prints, rather than throwing on the first one: which of the four
+// Every assertion prints, rather than throwing on the first one: which of the five
 // works and which does not is the whole answer.
 let failed = 0;
 const check = (ok, label) => {
@@ -78,9 +78,39 @@ try {
 }
 check(/RecipesCam/.test(brand ?? ''), `offline reload of /app paints the app's own header: ${brand}`);
 
+// (e) The offer is asked once. The browser's sheet is stubbed, because a check cannot
+// click the real one: waved away it is a refusal, and a refusal is stored, so the next
+// visit renders no dialog at all. The stub goes in an init script so it is there on
+// both loads.
+await context.setOffline(false);
+await page.addInitScript(() => {
+  window.__offerInstall = () => {
+    const event = new Event('beforeinstallprompt');
+    event.prompt = () => Promise.resolve();
+    event.userChoice = Promise.resolve({ outcome: 'dismissed' });
+    window.dispatchEvent(event);
+    window.dispatchEvent(new Event('rc:install-offer'));
+  };
+});
+const offer = async () => {
+  await page.evaluate(() => window.__offerInstall());
+  await page.waitForTimeout(150);
+  return page.locator('[data-key="install-yes"]').count();
+};
+await page.reload();
+const first = await offer();
+await page.locator('[data-key="install-yes"]').click();
+const stored = await page.evaluate(() => localStorage.getItem('rc.install.dismissed.v1'));
+await page.reload();
+const again = await offer();
+check(
+  first === 1 && stored === '1' && again === 0,
+  `install dialog shown ${first} time(s), refused (localStorage '${stored}'), shown again after reload: ${again}`,
+);
+
 await browser.close();
 if (failed) {
-  console.error(`pwa-check: ${failed} of 4 failed`);
+  console.error(`pwa-check: ${failed} of 5 failed`);
   process.exit(1);
 }
 console.log('pwa-check ok');