diff --git a/src/testium/main_win/desktop_integration.py b/src/testium/main_win/desktop_integration.py
new file mode 100644
index 0000000..c60c2fc
--- /dev/null
+++ b/src/testium/main_win/desktop_integration.py
@@ -0,0 +1,95 @@
+"""Install a desktop entry + icon under the user's data dir so desktop shells
+show the testium icon in the task bar / dock.
+
+On a native Wayland session GNOME takes a window's task-bar icon from the
+``.desktop`` file whose name (or ``StartupWMClass``) matches the window
+``app_id`` — ``QGuiApplication.setWindowIcon`` is ignored there. The portable
+channels (source checkout, PyInstaller binary, AppImage) install no system
+desktop file, so we drop an idempotent one in ``~/.local/share``. The window
+``app_id`` is set to ``testium`` (see ``QApplication.setDesktopFileName`` in
+``testium_win``), which is exactly this file's base name.
+
+Flatpak ships its own ``org.testium.Testium.desktop`` and keeps its own app id,
+so the caller skips this integration there.
+"""
+import os
+import sys
+
+from PySide6.QtCore import Qt
+from PySide6.QtGui import QPixmap
+
+# Must match QApplication.setDesktopFileName(...) for the GUI, and is used as
+# both the desktop-file base name and the StartupWMClass.
+APP_ID = "testium"
+
+
+def _launch_command():
+    """Best-effort Exec= for the menu entry. Not needed for icon matching, but
+    makes the entry actually launchable when possible."""
+    appimage = os.environ.get("APPIMAGE")
+    if appimage:
+        return f'"{appimage}"'
+    if getattr(sys, "frozen", False):
+        return f'"{os.path.abspath(sys.executable)}"'
+    argv0 = os.path.abspath(sys.argv[0]) if sys.argv and sys.argv[0] else ""
+    if argv0 and os.path.exists(argv0):
+        return f'"{os.path.abspath(sys.executable)}" "{argv0}"'
+    return f'"{os.path.abspath(sys.executable)}" -m testium'
+
+
+def ensure_desktop_entry():
+    """Create (or refresh) ~/.local/share icon + desktop entry. Best-effort:
+    any failure is swallowed so it can never take the GUI down.
+
+    Freedesktop-only: a no-op off Linux (Windows / macOS use the window icon)."""
+    if not sys.platform.startswith("linux"):
+        return
+    try:
+        data_home = os.environ.get("XDG_DATA_HOME") or os.path.join(
+            os.path.expanduser("~"), ".local", "share"
+        )
+        icon_dir = os.path.join(data_home, "icons", "hicolor", "256x256", "apps")
+        app_dir = os.path.join(data_home, "applications")
+        icon_path = os.path.join(icon_dir, f"{APP_ID}.png")
+        desktop_path = os.path.join(app_dir, f"{APP_ID}.desktop")
+
+        os.makedirs(icon_dir, exist_ok=True)
+        os.makedirs(app_dir, exist_ok=True)
+
+        # Icon: render the bundled Qt resource to a PNG once. Requires a live
+        # QGuiApplication (the caller creates it before calling us).
+        if not os.path.isfile(icon_path):
+            pixmap = QPixmap(u":/black/testium_logo.png")
+            if not pixmap.isNull():
+                pixmap = pixmap.scaled(
+                    256, 256,
+                    Qt.AspectRatioMode.KeepAspectRatio,
+                    Qt.TransformationMode.SmoothTransformation,
+                )
+                pixmap.save(icon_path, "PNG")
+
+        # Absolute Icon= path so the shell resolves it without an icon-cache
+        # refresh; StartupWMClass lets X11 / XWayland match too.
+        desktop = (
+            "[Desktop Entry]\n"
+            "Type=Application\n"
+            "Name=Testium\n"
+            "Comment=Test sequencer\n"
+            f"Icon={icon_path}\n"
+            f"Exec={_launch_command()} %f\n"
+            "Terminal=false\n"
+            f"StartupWMClass={APP_ID}\n"
+            "Categories=Utility;Development;\n"
+        )
+
+        # Write only when missing or changed, to avoid needless menu churn.
+        current = None
+        if os.path.isfile(desktop_path):
+            with open(desktop_path, "r") as fh:
+                current = fh.read()
+        if current != desktop:
+            with open(desktop_path, "w") as fh:
+                fh.write(desktop)
+    except Exception:
+        # Desktop integration is a nicety, never a hard requirement.
+        pass
diff --git a/src/testium/main_win/testium_win.py b/src/testium/main_win/testium_win.py
index be6a3b1..23267f0 100755
--- a/src/testium/main_win/testium_win.py
+++ b/src/testium/main_win/testium_win.py
@@ -678,6 +678,24 @@ def MainWin(
     debug=False,
 ):
     app = QApplication(sys.argv)
+    # Application identity so desktop shells (GNOME, ...) show the testium
+    # icon in the task bar / dock instead of a generic one. On Wayland this
+    # sets the surface app_id; on X11/XWayland it sets WM_CLASS, so the window
+    # stops inheriting the launcher's class (e.g. "python3" under the AppImage,
+    # which is what GNOME was keying the wrong icon off) and the window icon
+    # below is used as the fallback. In Flatpak the id must be the Flatpak app
+    # id so it matches the installed desktop file.
+    app.setApplicationName("Testium")
+    app.setApplicationDisplayName("Testium")
+    app.setDesktopFileName(os.environ.get("FLATPAK_ID", "testium"))
+    app.setWindowIcon(QIcon(u":/black/testium_logo.png"))
+    # On native Wayland the task-bar icon comes from an installed desktop file
+    # matched to the app_id, not from setWindowIcon(). Flatpak ships its own;
+    # for the other Linux channels drop an idempotent one under ~/.local/share.
+    # Windows / macOS use the window icon set above, so this is Linux-only.
+    if sys.platform.startswith("linux") and not os.environ.get("FLATPAK_ID"):
+        from main_win.desktop_integration import ensure_desktop_entry
+        ensure_desktop_entry()
     ui = MainWindow(
         test_file,
         config_files,