NDI discovery

tests/RenderCadenceCompositorAppConfigProviderTests.cpp

@@ -149,6 +149,46 @@ void TestConfigJsonRoundTrip()
 	Expect(parsed.runtimeShaderId == "solid-color", "runtime shader id round trips");
 }
 
+void TestOutputAlphaNormalizesLegacyKeying()
+{
+	using namespace RenderCadenceCompositor;
+
+	const std::string deckLinkJson =
+		"{"
+		"\"output\":{"
+		"\"backend\":\"decklink\","
+		"\"keying\":{\"external\":true,\"alphaRequired\":false}"
+		"}"
+		"}";
+
+	AppConfig parsed;
+	std::string error;
+	Expect(ParseAppConfigJson(deckLinkJson, parsed, error), "legacy DeckLink keying config parses");
+	Expect(parsed.output.externalKeyingEnabled, "DeckLink external keying remains enabled");
+	Expect(parsed.output.outputAlphaRequired, "DeckLink external keying implies output alpha");
+
+	const std::filesystem::path path = std::filesystem::temp_directory_path() / "render-cadence-compositor-config-alpha-test.json";
+	std::ofstream output(path, std::ios::binary);
+	output
+		<< "{\n"
+		<< "  \"output\": {\n"
+		<< "    \"backend\": \"ndi\",\n"
+		<< "    \"keying\": {\n"
+		<< "      \"external\": true,\n"
+		<< "      \"alphaRequired\": false\n"
+		<< "    }\n"
+		<< "  }\n"
+		<< "}\n";
+	output.close();
+
+	AppConfigProvider provider;
+	Expect(provider.Load(path, error), "legacy NDI keying config loads");
+	Expect(provider.Config().output.outputAlphaRequired, "legacy external keying implies NDI output alpha");
+	Expect(!provider.Config().output.externalKeyingEnabled, "NDI ignores external keying backing field");
+
+	std::filesystem::remove(path);
+}
+
 void TestHelpers()
 {
 	using namespace RenderCadenceCompositor;
@@ -178,6 +218,7 @@ int main()
 	TestCommandLineOverrides();
 	TestPreviewDefaultsAreOptIn();
 	TestConfigJsonRoundTrip();
+	TestOutputAlphaNormalizesLegacyKeying();
 	TestHelpers();
 
 	if (gFailures != 0)