setup_application() calls QApplication.setDesktopFileName(PICARD_APP_NAME), i.e. "Picard". Per the freedesktop Desktop Entry Specification this must be the base name of the installed desktop entry without the ".desktop" suffix. The installed entry is org.musicbrainz.Picard.desktop, so the correct value is "org.musicbrainz.Picard" (PICARD_APP_ID), not "Picard".

Because the reported name does not match the installed desktop entry, the desktop portal cannot associate the running process with its entry. On startup this logs:

    qt.qpa.services: Failed to register with host portal ("org.freedesktop.portal.Error.Failed", "Could not register app ID: App info not found for 'Picard'")

On Wayland the surface app_id is derived from desktopFileName, so compositors that map app_id to <id>.desktop fail to find the entry, resulting in a wrong/missing taskbar icon and no window grouping.

Regression: introduced in commit ef2fafd (PICARD-2331), which correctly dropped the ".desktop" suffix but used PICARD_APP_NAME instead of PICARD_APP_ID.

Fix: pass PICARD_APP_ID to QApplication.setDesktopFileName().

Affects: X11 and Wayland packaged installs (distro packages, Flatpak, AppImage). No effect on Windows/macOS/Haiku (desktopFileName is not read by those platform plugins).