feat(tui): identify Fenris and explain polkit authentication

tests/test_tui.py

@@ -384,6 +384,35 @@ class TestDenseScreen:
             assert "timer:" in strip
             assert "last collect:" in strip
             assert "freshness:" in strip
+            assert "by Bongbetic" in strip
+
+    @pytest.mark.asyncio
+    async def test_branding_and_one_time_auth_banner(self, tmp_path):
+        """Identity is visible at launch; auth notice clears once per session."""
+        app = FenrisTuiApp(
+            store_path=tmp_path / "nonexistent.db",
+            refresh_interval_s=0.2,
+        )
+        auth_notice = "privileged actions will prompt for authentication (polkit)"
+
+        async with app.run_test() as pilot:
+            headline = str(app.query_one("#headline-band").render())
+            assert "Fenris — NVMe endurance monitor" in headline
+            assert auth_notice in headline
+            assert "by Bongbetic" in str(app.query_one("#service-strip").render())
+
+            await pilot.pause(0.25)
+            assert auth_notice not in str(app.query_one("#headline-band").render())
+
+            await pilot.pause(0.25)
+            assert auth_notice not in str(app.query_one("#headline-band").render())
+
+        fresh_app = FenrisTuiApp(
+            store_path=tmp_path / "nonexistent.db",
+            refresh_interval_s=0.2,
+        )
+        async with fresh_app.run_test():
+            assert auth_notice in str(fresh_app.query_one("#headline-band").render())
 
 
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