Re-read the import line on a timer, so its figures move while watched

The indicator is re-read when the server publishes, and an import
publishes when a page of its listing is done. A Gmail import spends most
of its time fetching what the listing named and says nothing meanwhile,
so the count, the messages a minute and the seconds until Google lets it
continue all stood still.

While the indicator shows an import it is now re-read every five seconds
with the list open and every thirty with it shut; never in a hidden tab,
and never when nothing is importing.

The import line's own test spent more than the pacer's reserve and was
made to wait eight seconds for it; it spends less.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

assets/controllers/mail/jobs_controller.js

@@ -13,6 +13,17 @@ import { Controller } from "@hotwired/stimulus";
  * in a few seconds is a lot of requests to say something that changed by two
  * percent. A trailing reload keeps the last one, so the FINAL state — the one
  * that says done, or failed — always lands.
+ *
+ * AND ON A TIMER WHILE AN IMPORT IS SHOWN. A job publishes as it goes; an
+ * import publishes when a page of its listing is done, and a Gmail import
+ * spends most of its hours fetching what the listing named, saying nothing.
+ * Its line also carries figures that move by themselves — messages a minute,
+ * the seconds until Google lets it continue — and a countdown that only
+ * changes when something else happens is not one. So while the indicator has
+ * an import line in it, it is re-read every few seconds: often with the list
+ * open, where somebody is watching, and seldom with it shut. Not at all in a
+ * tab nobody is looking at, and not at all when nothing is importing, which
+ * is nearly always.
  */
 /** The list of work inside the indicator, and the button that opens it. */
 const MENU = "[data-ui--dropdown-target='menu']";
@@ -24,13 +35,36 @@ export default class extends Controller {
     /** Milliseconds between reloads while a job is running. */
     static THROTTLE = 1500;
 
+    /** Milliseconds between looks at an import: list open, and list shut. */
+    static WATCHED = 5000;
+    static UNWATCHED = 30000;
+
     connect() {
         this._lastAt = 0;
         this._pending = null;
+        this._watch = setInterval(() => this.#watchImport(), this.constructor.WATCHED);
     }
 
     disconnect() {
         clearTimeout(this._pending);
+        clearInterval(this._watch);
+    }
+
+    #watchImport() {
+        const frame = document.getElementById("jobs-indicator");
+
+        if (true === document.hidden || null === frame || null === frame.querySelector("[data-import-line]")) {
+            return;
+        }
+
+        const open = null !== frame.querySelector(`${MENU}:not([hidden])`);
+        const due = true === open ? this.constructor.WATCHED : this.constructor.UNWATCHED;
+
+        // A little under, so a timer that fires a few milliseconds early does
+        // not wait a whole round more.
+        if (Date.now() - this._lastAt >= due - 250) {
+            this.refresh();
+        }
     }
 
     refresh() {

tests/Service/Mail/ImportProgressTest.php

@@ -190,15 +190,16 @@ final class ImportProgressTest extends KernelTestCase
         $this->em->flush();
 
         $pacer = static::getContainer()->get(GmailQuotaPacer::class);
-        $pacer->spend($this->account, 2000);
+        // Within the reserve, so the pacer does not make the test wait.
+        $pacer->spend($this->account, 400);
 
         $line = $this->progress->forUser($this->user)[0];
 
         self::assertNotNull($line->quota);
         self::assertSame(15_000, $line->quota->limit);
         self::assertFalse($line->quota->learnt);
-        self::assertSame(2000, $line->quota->used);
-        self::assertSame(100, $line->quota->messagesPerMinute, '2,000 units at twenty a message');
+        self::assertSame(400, $line->quota->used);
+        self::assertSame(20, $line->quota->messagesPerMinute, '400 units at twenty a message');
         self::assertFalse($line->quota->isPaused());
 
         $running = static::getContainer()->get(Environment::class)->render('mail/_jobs_indicator.html.twig', [
@@ -206,7 +207,7 @@ final class ImportProgressTest extends KernelTestCase
             'imports' => [$line],
         ]);
 
-        self::assertStringContainsString('About 100 messages a minute', $running);
+        self::assertStringContainsString('About 20 messages a minute', $running);
         // 9,000 messages at 450 a minute, which is three fifths of 15,000
         // units at twenty a message.
         self::assertSame(20, $line->quota->minutesLeft);