fix(config_flow): no_state_source fires only when none of the three sources is present — ADB-only standalone is valid; strings/docs name all three (F2)

tests/test_standalone_setup.py

@@ -256,6 +256,40 @@ class TestStandaloneValidation:
         assert CONF_ANDROIDTV_ENTITY not in result["data"]
 
 
+class TestAdbOnlyStandalone:
+    async def test_adb_only_standalone_is_valid(self, tmp_path):
+        """F2: ADB media-session mode is a third accepted state source."""
+        module = _form_module()
+        flow = module.NvidiaShieldConfigFlow()
+        flow.hass = FakeHass(str(tmp_path))
+
+        result = await flow.async_step_user(
+            _user_input(
+                **{
+                    CONF_ANDROIDTV_ENTITY: "",
+                    CONF_PROTOCOL_ENABLED: False,
+                    "adb_enabled": True,
+                }
+            )
+        )
+
+        # routed into ADB pairing — no no_state_source error
+        assert result["type"] == "form"
+        assert result["step_id"] == "adb_pair"
+        assert result["errors"] == {}
+
+    async def test_error_still_fires_with_no_source_at_all(self, tmp_path):
+        module = _form_module()
+        flow = module.NvidiaShieldConfigFlow()
+        flow.hass = FakeHass(str(tmp_path))
+
+        result = await flow.async_step_user(
+            _user_input(**{CONF_ANDROIDTV_ENTITY: "", "adb_enabled": False})
+        )
+
+        assert result["errors"] == {"base": "no_state_source"}
+
+
 class TestMigrationKeepsOrAllowsAbsence:
     async def test_v1_to_v2_keeps_the_androidtv_field(self, tmp_path):
         module = _entry_module()