Link one tab icon so the chosen one is not outvoted by the wax seal (#74)

Every page linked the per-account SVG tab icon and, after it, a static 192px wax-seal PNG. Firefox stores an SVG icon at width 65535 and a PNG at its declared size, and picks the smallest icon that is big enough for a tab, so the PNG won and every account saw the wax seal whatever it picked in Settings → Appearance → Logo.

The PNG tab-icon link is gone, so the SVG is the only tab icon. The apple-touch-icon and the manifest keep their PNGs. A browser with no SVG tab-icon support gets no tab icon instead of the wrong one.

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

CHANGELOG.md

@@ -8,6 +8,12 @@ The published image tags: `latest` follows the most recent release below,
 
 ## Unreleased
 
+**The tab icon is the one you picked, in Firefox too.** Settings → Appearance → Logo changed the
+icon in the app but not in the tab, which kept showing the wax seal. Every page also linked a
+fixed 192px wax-seal PNG as a second tab icon, and Firefox prefers that to the SVG for a tab. The
+PNG is gone from the tab icons; the home-screen and install icons are unchanged. No migration.
+[#74](https://github.com/karatektus/pl_mail/pull/74), by @Flouss.
+
 **A message with a stray non-UTF-8 byte in the wrong place was never stored.** Over IMAP, a mail
 whose text was labelled `us-ascii` but written in Latin-1 — "Grüße" from a mailer nobody configured
 — was refused by the database ("invalid byte sequence for encoding UTF8: 0xfc"), asked for again

templates/_partials/_favicon.html.twig

@@ -12,10 +12,18 @@
     operating system happens to draw. A tab strip is where people find plMail
     among thirty other tabs, and the thing they look for is the icon.
 
-    Now the real mark, in the same two forms every other icon here takes:
-    an SVG that stays sharp at 16px and any pixel ratio, and the 192px PNG for
-    anything that will not take an SVG favicon. Browsers pick the first `rel`
-    they understand, so the SVG is listed first.
+    Now the real mark, as an SVG that stays sharp at 16px and any pixel ratio.
+
+    It is the ONLY tab icon linked, and that is deliberate. This used to be
+    followed by `<link rel="icon" type="image/png" sizes="192x192"
+    href="/icons/icon-192.png">` as a fallback, and the fallback won: Firefox
+    stores an SVG icon at width 65535 and a PNG at its declared size, and picks
+    the smallest icon that is big enough for the tab, which is the 192px PNG.
+    A static file can only wear the product default, so every account saw the
+    wax seal in its tabs whatever icon it had chosen. A second candidate can
+    only be wrong for someone. The PNGs still serve the places that need a
+    raster and have no per-account route: the apple-touch-icon in app.html.twig
+    and the manifest's install icons.
 
     The SVG comes from a route rather than a file, because the logo is a
     per-user setting now (Settings → Appearance → Logo: an icon, then its
@@ -30,4 +38,3 @@
    it live on every pick (see repaintLogo) — before the save has landed, which
    is why the drawing cannot come from the session. See BrandingController. #}
 <link rel="icon" type="image/svg+xml" href="{{ logo_favicon_url(appearance().effectiveLogoMotif, appearance().effectiveLogoPaint) }}">
-<link rel="icon" type="image/png" sizes="192x192" href="/icons/icon-192.png">

tests/Controller/BrandingFaviconTest.php

@@ -58,6 +58,29 @@ final class BrandingFaviconTest extends WebTestCase
         }
     }
 
+    /**
+     * A page links ONE tab icon, and it is the route's.
+     *
+     * Firefox files an SVG tab icon under width 65535 and a PNG under its
+     * declared size, then answers "which icon for a 16px tab" with the smallest
+     * one that is big enough, so a 192px PNG always beat the SVG. The PNG is a
+     * static file and wears the product default, so every account saw the wax
+     * seal in its tabs whatever it had chosen. The home-screen and install
+     * icons keep their PNGs (apple-touch-icon, the manifest); only the tab
+     * icon must not have a second candidate.
+     */
+    public function testNoRasterTabIconCompetesWithTheChosenOne(): void
+    {
+        $client = static::createClient();
+
+        $icons = $client->request('GET', '/login')->filter('link[rel~="icon"]');
+
+        // The presence companion: with no tab icon at all the check below would
+        // pass on an empty head.
+        self::assertCount(1, $icons, 'exactly one tab icon is linked');
+        self::assertSame('image/svg+xml', $icons->attr('type'), 'and it is the per-account SVG route');
+    }
+
     public function testTheTabIconWearsTheUsersChoice(): void
     {
         [$client, $user] = $this->signedIn();