clean split

README.md

@@ -30,6 +30,8 @@ Native app internals are grouped by boundary:
 - `video/playout/`: backend-adjacent playout policy, queues, frame pools, and scheduling helpers.
 - `video/legacy/`: older backend pipeline pieces kept separate while the new edge model settles.
 
+The runtime shader stack is plugged into the host through `src/app/RuntimeContentController.h`. The checked-in app wires `ShaderRuntimeContentController` into that slot; a fork can provide another runtime-content controller for a larger render engine while keeping the cadence/video I/O shell.
+
 ## Requirements
 
 - Windows with Visual Studio 2022 C++ tooling.

docs/FORKING_RENDER_CADENCE_BASE.md

@@ -6,7 +6,9 @@ This note captures the fork-readiness review for using this repository as a base
 
 The repository is clean enough for an internal fork, but it needs a small hygiene pass before it becomes a comfortable long-lived base repo.
 
-The important architecture is already in place: render cadence, video input/output, frame exchange, readback, preview, control, and shader build work are mostly separated by role. The main replacement point is the render-content adapter in `src/render/RuntimeShaderRenderContent.*`, where the current shader-package renderer decides what to draw into the framebuffer handed to it by `RenderThread`.
+The important architecture is already in place: render cadence, video input/output, frame exchange, readback, preview, control, and shader build work are mostly separated by role. The app-side replacement point is now `IRuntimeContentController` in `src/app/RuntimeContentController.h`. The current shader package stack is plugged in by `ShaderRuntimeContentController`, while a fork can provide a D3D-engine controller without making the host app own Slang, shader catalogs, or shader layer state.
+
+The current render-thread implementation still uses OpenGL for its context and readback path. If the fork's renderer is truly D3D rather than GL content, keep the app/video/frame-exchange boundary and replace the render-thread/content implementation that publishes completed system-memory frames.
 
 For a new repo, keep the cadence and frame handoff machinery, then replace or narrow the runtime shader rendering layer.
 
@@ -23,6 +25,7 @@ These parts are the useful base for the fork:
 - `src/app`: startup, config, video backend factory, runtime layer orchestration, preview, telemetry, and HTTP server hookup.
 - `src/control/http`, `src/control/osc`, `src/telemetry`, `src/logging`, and `ui`: useful if the new repo still wants a local control surface. `control/osc` is currently a status/lifecycle stub, not a UDP listener.
 - `src/app/RenderCadenceHttpRoutes.*`: useful only if the new repo keeps this app's current `/api/...` control surface.
+- `src/app/RuntimeContentController.h`: the app-side runtime-content boundary. Keep the interface shape and provide a fork-owned implementation for D3D engine control/state.
 
 ## Replace Or Rework
 
@@ -31,6 +34,7 @@ These are most likely to change when the fork renders something other than shade
 - `src/render/runtime`: current runtime shader scene, renderer, text texture cache, and shared-context shader preparation.
 - `src/runtime/shader`: background Slang package build bridge.
 - `src/shader`: shader package manifest parsing and Slang wrapper generation, unless the new renderer keeps the same shader package contract.
+- `src/app/ShaderRuntimeContentController.*`: current Slang shader-stack implementation of the app runtime-content boundary.
 - `shaders/`: bundled shader package library.
 - `runtime/templates/shader_wrapper.slang.in`: only needed for the current Slang package pipeline.
 - `src/app/RenderCadenceHttpRoutes.*`: replace this with a fork-owned route module if the new renderer has different controls, while keeping `src/control/http/HttpControlServer.*` as the socket/static/WebSocket shell.
@@ -38,6 +42,8 @@ These are most likely to change when the fork renders something other than shade
 
 The first fork step is now in place: `RenderThread` preserves the cadence/readback shell and calls a narrow render-content interface behind the draw call. A new repo can swap that implementation without touching video I/O scheduling.
 
+The shader stack is also separated from `RenderCadenceApp` now. The app owns only an `IRuntimeContentController`; `RenderCadenceCompositor.cpp` wires the current `ShaderRuntimeContentController` into that slot. A D3D fork should wire a D3D runtime-content controller there and then replace the render-thread content/readback implementation as needed.
+
 The HTTP control boundary is also split now. `HttpControlServer` owns transport, static-file helpers, OpenAPI helper serving, and WebSocket state transport; `RenderCadenceHttpRoutes` owns this app's REST endpoint map. A fork that wants the same browser/server plumbing can provide its own route callback and leave the Render Cadence-specific endpoints behind.
 
 ## Current Swap Point
@@ -68,17 +74,18 @@ Before cutting a long-lived fork, fix or decide these items:
 - Keep `runtimeShaderId` empty in checked-in config unless this repo intentionally wants a default startup shader again.
 - Keep runtime third-party discovery aligned with CMake. Font atlas generation and Slang compilation now both check explicit tool roots, `THIRD_PARTY_ROOT`, the private `video-io-3rdParty` bundle, and legacy or packaged `3rdParty` layouts.
 - Make `config/runtime-host.json` portable. Current checked-in defaults include a local NDI source name and DeckLink output.
-- Decide whether the fork keeps the Slang shader package contract. If not, retire or clearly isolate `shaders/SHADER_CONTRACT.md`, shader package UI, and shader manifest tests.
+- Decide whether the fork keeps the Slang shader package contract. If not, replace `ShaderRuntimeContentController`, retire or clearly isolate `shaders/SHADER_CONTRACT.md`, shader package UI, and shader manifest tests.
+- For a D3D engine fork, decide whether to bridge D3D output into the existing GL/readback path temporarily or replace `RenderThread`/readback with a D3D-native publisher that still writes completed `SystemFrameExchange` frames.
 - Mark older docs that reference `apps/LoopThroughWithOpenGLCompositing` as historical, or update them to point at the current `src/` implementation.
 - Keep `runtime/` generated output ignored, and keep only `runtime/templates/` plus `runtime/README.md` tracked.
 - Keep the private SDK bundle as a submodule only if the new repo is intended for the same org/build environment. External forks should use ignored `3rdParty/` or explicit CMake SDK paths.
 
 ## Verification Snapshot
 
-Last checked locally on 2026-05-30 after the Slang lookup alignment:
+Last checked locally on 2026-05-30 after the runtime-content controller split:
 
 - UI production build passed with `npm.cmd run build`.
-- Native debug build passed for `RenderCadenceCompositor`, `ShaderSlangValidationTests`, and `ShaderCompilerLookupTests`.
+- Native debug build passed for `RenderCadenceCompositor`.
 - Native tests passed 26 of 26 with `ctest --test-dir build\vs2022-x64-debug -C Debug --output-on-failure`.
 - `FontAtlasBuilderTests` now passes with `msdf-atlas-gen.exe` supplied by the private `video-io-3rdParty/msdf-atlas-gen` bundle.
 - `ShaderCompilerLookupTests` covers `SLANG_ROOT`, `THIRD_PARTY_ROOT`, repo `video-io-3rdParty`, legacy `3rdParty`, and packaged `3rdParty/slang` Slang layouts.
@@ -88,9 +95,9 @@ The generated Visual Studio `RUN_TESTS` target did not build missing test execut
 ## Recommended Fork Sequence
 
 1. Make the hygiene fixes above in this repo or immediately after the fork.
-2. Keep `IRenderContent` as the boundary behind the `RenderThread` draw call.
-3. Keep `RuntimeShaderRenderContent` as the baseline implementation until the fork's renderer exists.
-4. Add the new renderer beside it or replace the default adapter.
+2. Keep `IRuntimeContentController` as the app-side boundary and replace `ShaderRuntimeContentController` with the fork's D3D engine control/state implementation.
+3. Keep `IRenderContent` as the render-thread draw-call boundary only if the fork remains GL-backed or uses a GL/D3D bridge.
+4. If the fork is D3D-native, replace the render-thread/readback implementation while preserving completed-frame publication into `SystemFrameExchange`.
 5. Verify that video output still consumes completed frames and never requests rendering directly.
 6. Only then remove shader package pieces that the new repo no longer needs.
 

src/README.md

@@ -66,6 +66,7 @@ Included now:
 - app-owned display/render layer model for shader build readiness
 - app-owned submission of a completed shader artifact
 - render-thread-owned render-content interface with runtime shader content as the default implementation
+- app-owned runtime-content controller interface with the Slang shader stack as the default implementation
 - render-thread-owned runtime render scene for ready shader layers inside the default render-content adapter
 - shared-context GL prepare worker for runtime shader program compile/link
 - render-thread-only GL program swap once a prepared program is ready
@@ -265,6 +266,12 @@ The HTTP server runs on its own thread. `control/http/HttpControlServer` owns so
 
 `control/osc/OscControlServer` is currently a lifecycle/status stub. It consumes the startup OSC config and reports whether OSC is configured or disabled, but it deliberately does not open a UDP socket or dispatch parameter changes yet.
 
+## Runtime Content Boundary
+
+`app/RenderCadenceApp` owns startup, video output, preview, telemetry, OSC status, and HTTP server lifetime. It does not own the Slang shader stack directly. Runtime content is supplied through `IRuntimeContentController` in `app/RuntimeContentController.h`.
+
+The default implementation is `ShaderRuntimeContentController`. It wraps `RuntimeLayerController`, exposes shader catalog/layer state to `/api/state`, handles the shader layer POST commands, and publishes render-ready shader layers to the current render thread. A fork that uses a D3D engine should replace this controller with a D3D engine controller and decide separately whether to keep the current GL render/readback thread as a bridge or replace it with a D3D-native frame publisher.
+
 ## Optional DeckLink Output
 
 DeckLink output is an optional edge service in this app.

src/RenderCadenceCompositor.cpp

@@ -2,6 +2,7 @@
 #include "app/AppConfigProvider.h"
 #include "app/AppRestart.h"
 #include "app/RenderCadenceApp.h"
+#include "app/ShaderRuntimeContentController.h"
 #include "app/VideoBackendFactory.h"
 #include "frames/InputFrameMailbox.h"
 #include "frames/SystemFrameExchange.h"
@@ -16,8 +17,10 @@
 #include <chrono>
 #include <cctype>
 #include <iostream>
+#include <memory>
 #include <sstream>
 #include <string>
+#include <vector>
 
 namespace
 {
@@ -196,11 +199,16 @@ int main(int argc, char** argv)
 	RenderThread renderThread(frameExchange, &inputMailbox, renderConfig);
 
 	auto outputBackend = RenderCadenceCompositor::CreateVideoOutputBackend(appConfig);
+	auto runtimeContent = std::make_unique<RenderCadenceCompositor::ShaderRuntimeContentController>(
+		[&renderThread](const std::vector<RenderCadenceCompositor::RuntimeRenderLayerModel>& layers) {
+			renderThread.SubmitRuntimeRenderLayers(layers);
+		});
 	RenderCadenceCompositor::RenderCadenceApp<RenderThread, SystemFrameExchange> app(
 		renderThread,
 		frameExchange,
 		appConfig,
 		std::move(outputBackend),
+		std::move(runtimeContent),
 		configProvider.SourcePath());
 	app.SetVideoInputMetricsProvider([inputBackend = inputBackend.get()]() {
 		return inputBackend ? inputBackend->Metrics() : RenderCadenceCompositor::VideoInputEdgeMetrics();

src/app/RenderCadenceApp.h

@@ -5,7 +5,7 @@
 #include "AppConfigProvider.h"
 #include "AppRestart.h"
 #include "RenderCadenceHttpRoutes.h"
-#include "RuntimeLayerController.h"
+#include "RuntimeContentController.h"
 #include "../logging/Logger.h"
 #include "../control/RuntimeStateJson.h"
 #include "../control/osc/OscControlServer.h"
@@ -65,20 +65,19 @@ public:
 		SystemFrameExchange& frameExchange,
 		AppConfig config,
 		std::unique_ptr<IVideoOutputEdge> output,
+		std::unique_ptr<IRuntimeContentController> runtimeContent,
 		std::filesystem::path configPath = std::filesystem::path()) :
 		mRenderThread(renderThread),
 		mFrameExchange(frameExchange),
 		mConfig(config),
 		mConfigPath(std::move(configPath)),
 		mOutput(std::move(output)),
+		mRuntimeContent(std::move(runtimeContent)),
 		mOutputThread(*mOutput, mFrameExchange, VideoOutputThreadConfig{
 			mConfig.outputThread.targetBufferedFrames,
 			mConfig.outputThread.idleSleep
 		}),
-		mTelemetryHealth(mConfig.telemetry),
-		mRuntimeLayers([this](const std::vector<RuntimeRenderLayerModel>& layers) {
-			mRenderThread.SubmitRuntimeRenderLayers(layers);
-		})
+		mTelemetryHealth(mConfig.telemetry)
 	{
 	}
 
@@ -92,10 +91,8 @@ public:
 
 	bool Start(std::string& error)
 	{
-		mRuntimeLayers.Initialize(
-			mConfig.shaderLibrary,
-			static_cast<unsigned>(mConfig.maxTemporalHistoryFrames),
-			mConfig.runtimeShaderId);
+		if (mRuntimeContent)
+			mRuntimeContent->Initialize(mConfig);
 
 		Log("app", "Starting render thread.");
 		if (!detail::StartRenderThread(mRenderThread, error, 0))
@@ -104,7 +101,8 @@ public:
 			Stop();
 			return false;
 		}
-		mRuntimeLayers.StartStartupBuild(mConfig.runtimeShaderId);
+		if (mRuntimeContent)
+			mRuntimeContent->Start();
 
 		if (!BuildSettledOutputReserve(error))
 		{
@@ -131,7 +129,8 @@ public:
 		mPreviewWindow.Stop();
 		mOutputThread.Stop();
 		mOutput->Stop();
-		mRuntimeLayers.Stop();
+		if (mRuntimeContent)
+			mRuntimeContent->Stop();
 		mRenderThread.Stop();
 		mOutput->ReleaseResources();
 		if (mStarted)
@@ -260,23 +259,15 @@ private:
 		routeCallbacks.getNdiSourcesJson = [this]() {
 			return BuildNdiSourcesJson();
 		};
-		routeCallbacks.addLayer = [this](const std::string& body) {
-			return mRuntimeLayers.HandleAddLayer(body);
-		};
-		routeCallbacks.removeLayer = [this](const std::string& body) {
-			return mRuntimeLayers.HandleRemoveLayer(body);
-		};
 		routeCallbacks.executePost = [this](const std::string& path, const std::string& body) {
 			if (path == "/api/config/save")
 				return HandleConfigSave(body);
 			if (path == "/api/app/restart")
 				return HandleAppRestart();
 
-			RuntimeControlCommand command;
-			std::string error;
-			if (!ParseRuntimeControlCommand(path, body, command, error))
-				return ControlActionResult{ false, error };
-			return mRuntimeLayers.HandleControlCommand(command);
+			if (mRuntimeContent)
+				return mRuntimeContent->HandlePost(path, body);
+			return ControlActionResult{ false, "No runtime content controller is active." };
 		};
 
 		HttpControlServerCallbacks callbacks;
@@ -320,17 +311,27 @@ private:
 	{
 		CadenceTelemetrySnapshot telemetry = mHttpTelemetry.Sample(mFrameExchange, *mOutput, mOutputThread, mRenderThread);
 		ApplyVideoInputMetrics(telemetry);
-		RuntimeLayerModelSnapshot layerSnapshot = mRuntimeLayers.Snapshot(telemetry);
-		return RuntimeStateToJson(RuntimeStateJsonInput{
+		RuntimeStateJsonInput stateInput{
 			mConfig,
 			telemetry,
 			mHttpServer.Port(),
 			mVideoOutputEnabled,
 			mVideoOutputStatus,
-			mRuntimeLayers.ShaderCatalog(),
-			layerSnapshot,
 			&mOscServer.State()
-		});
+		};
+		if (mRuntimeContent)
+		{
+			stateInput.writeRuntimeJson = [this, telemetry](JsonWriter& writer) {
+				mRuntimeContent->WriteRuntimeJson(writer, telemetry);
+			};
+			stateInput.writeCatalogJson = [this](JsonWriter& writer) {
+				mRuntimeContent->WriteCatalogJson(writer);
+			};
+			stateInput.writeLayersJson = [this, telemetry](JsonWriter& writer) {
+				mRuntimeContent->WriteLayersJson(writer, telemetry);
+			};
+		}
+		return RuntimeStateToJson(stateInput);
 	}
 
 	void StartOscServer()
@@ -460,13 +461,13 @@ private:
 	AppConfig mConfig;
 	std::filesystem::path mConfigPath;
 	std::unique_ptr<IVideoOutputEdge> mOutput;
+	std::unique_ptr<IRuntimeContentController> mRuntimeContent;
 	VideoOutputThread<SystemFrameExchange> mOutputThread;
 	TelemetryHealthMonitor mTelemetryHealth;
 	CadenceTelemetry mHttpTelemetry;
 	HttpControlServer mHttpServer;
 	OscControlServer mOscServer;
 	PreviewWindowThread mPreviewWindow;
-	RuntimeLayerController mRuntimeLayers;
 	std::function<VideoInputEdgeMetrics()> mVideoInputMetricsProvider;
 	uint64_t mLastInputCapturedFrames = 0;
 	std::atomic<bool> mRestartRequired{ false };

src/app/RuntimeContentController.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include "AppConfig.h"
+#include "../control/ControlActionResult.h"
+#include "../json/JsonWriter.h"
+#include "../telemetry/CadenceTelemetry.h"
+
+#include <string>
+
+namespace RenderCadenceCompositor
+{
+class IRuntimeContentController
+{
+public:
+	virtual ~IRuntimeContentController() = default;
+
+	virtual void Initialize(AppConfig& config) = 0;
+	virtual void Start() = 0;
+	virtual void Stop() = 0;
+
+	virtual ControlActionResult HandlePost(const std::string& path, const std::string& body) = 0;
+	virtual void WriteRuntimeJson(JsonWriter& writer, const CadenceTelemetrySnapshot& telemetry) const = 0;
+	virtual void WriteCatalogJson(JsonWriter& writer) const = 0;
+	virtual void WriteLayersJson(JsonWriter& writer, const CadenceTelemetrySnapshot& telemetry) const = 0;
+};
+}

src/app/ShaderRuntimeContentController.cpp

@@ -0,0 +1,67 @@
+#include "ShaderRuntimeContentController.h"
+
+#include "../control/RuntimeControlCommand.h"
+#include "../control/RuntimeStateJson.h"
+
+#include <utility>
+
+namespace RenderCadenceCompositor
+{
+ShaderRuntimeContentController::ShaderRuntimeContentController(RenderLayerPublisher publisher) :
+	mRuntimeLayers(std::move(publisher))
+{
+}
+
+ShaderRuntimeContentController::~ShaderRuntimeContentController()
+{
+	Stop();
+}
+
+void ShaderRuntimeContentController::Initialize(AppConfig& config)
+{
+	mRuntimeLayers.Initialize(
+		config.shaderLibrary,
+		static_cast<unsigned>(config.maxTemporalHistoryFrames),
+		config.runtimeShaderId);
+	mStartupShaderId = config.runtimeShaderId;
+}
+
+void ShaderRuntimeContentController::Start()
+{
+	mRuntimeLayers.StartStartupBuild(mStartupShaderId);
+}
+
+void ShaderRuntimeContentController::Stop()
+{
+	mRuntimeLayers.Stop();
+}
+
+ControlActionResult ShaderRuntimeContentController::HandlePost(const std::string& path, const std::string& body)
+{
+	if (path == "/api/layers/add")
+		return mRuntimeLayers.HandleAddLayer(body);
+	if (path == "/api/layers/remove")
+		return mRuntimeLayers.HandleRemoveLayer(body);
+
+	RuntimeControlCommand command;
+	std::string error;
+	if (!ParseRuntimeControlCommand(path, body, command, error))
+		return ControlActionResult{ false, error };
+	return mRuntimeLayers.HandleControlCommand(command);
+}
+
+void ShaderRuntimeContentController::WriteRuntimeJson(JsonWriter& writer, const CadenceTelemetrySnapshot& telemetry) const
+{
+	WriteShaderRuntimeJson(writer, mRuntimeLayers.Snapshot(telemetry));
+}
+
+void ShaderRuntimeContentController::WriteCatalogJson(JsonWriter& writer) const
+{
+	WriteShaderCatalogJson(writer, mRuntimeLayers.ShaderCatalog());
+}
+
+void ShaderRuntimeContentController::WriteLayersJson(JsonWriter& writer, const CadenceTelemetrySnapshot& telemetry) const
+{
+	WriteRuntimeShaderLayersJson(writer, mRuntimeLayers.ShaderCatalog(), mRuntimeLayers.Snapshot(telemetry));
+}
+}

src/app/ShaderRuntimeContentController.h

@@ -0,0 +1,34 @@
+#pragma once
+
+#include "RuntimeContentController.h"
+#include "RuntimeLayerController.h"
+
+#include <string>
+#include <vector>
+
+namespace RenderCadenceCompositor
+{
+class ShaderRuntimeContentController final : public IRuntimeContentController
+{
+public:
+	using RenderLayerPublisher = RuntimeLayerController::RenderLayerPublisher;
+
+	explicit ShaderRuntimeContentController(RenderLayerPublisher publisher = RenderLayerPublisher());
+	ShaderRuntimeContentController(const ShaderRuntimeContentController&) = delete;
+	ShaderRuntimeContentController& operator=(const ShaderRuntimeContentController&) = delete;
+	~ShaderRuntimeContentController() override;
+
+	void Initialize(AppConfig& config) override;
+	void Start() override;
+	void Stop() override;
+
+	ControlActionResult HandlePost(const std::string& path, const std::string& body) override;
+	void WriteRuntimeJson(JsonWriter& writer, const CadenceTelemetrySnapshot& telemetry) const override;
+	void WriteCatalogJson(JsonWriter& writer) const override;
+	void WriteLayersJson(JsonWriter& writer, const CadenceTelemetrySnapshot& telemetry) const override;
+
+private:
+	RuntimeLayerController mRuntimeLayers;
+	std::string mStartupShaderId;
+};
+}

src/control/RuntimeStateJson.h

@@ -9,6 +9,7 @@
 #include "../telemetry/CadenceTelemetryJson.h"
 
 #include <cstdint>
+#include <functional>
 #include <string>
 #include <vector>
 
@@ -21,9 +22,10 @@ struct RuntimeStateJsonInput
 	unsigned short serverPort = 0;
 	bool videoOutputEnabled = false;
 	std::string videoOutputStatus;
-	const SupportedShaderCatalog& shaderCatalog;
-	const RuntimeLayerModelSnapshot& runtimeLayers;
 	const OscControlServerState* osc = nullptr;
+	std::function<void(JsonWriter&)> writeRuntimeJson;
+	std::function<void(JsonWriter&)> writeCatalogJson;
+	std::function<void(JsonWriter&)> writeLayersJson;
 };
 
 inline void WriteVideoIoStatusJson(JsonWriter& writer, const RuntimeStateJsonInput& input)
@@ -244,12 +246,56 @@ inline void WriteParameterDefinitionJson(JsonWriter& writer, const ShaderParamet
 	writer.EndObject();
 }
 
-inline void WriteLayersJson(JsonWriter& writer, const RuntimeStateJsonInput& input)
+inline void WriteShaderRuntimeJson(JsonWriter& writer, const RuntimeLayerModelSnapshot& runtimeLayers)
+{
+	writer.BeginObject();
+	writer.KeyUInt("layerCount", static_cast<uint64_t>(runtimeLayers.displayLayers.size()));
+	writer.KeyBool("compileSucceeded", runtimeLayers.compileSucceeded);
+	writer.KeyString("compileMessage", runtimeLayers.compileMessage);
+	writer.EndObject();
+}
+
+inline void WriteEmptyRuntimeJson(JsonWriter& writer)
+{
+	writer.BeginObject();
+	writer.KeyUInt("layerCount", 0);
+	writer.KeyBool("compileSucceeded", true);
+	writer.KeyString("compileMessage", "No runtime content controller is active.");
+	writer.EndObject();
+}
+
+inline void WriteShaderCatalogJson(JsonWriter& writer, const SupportedShaderCatalog& shaderCatalog)
 {
 	writer.BeginArray();
-	for (const RuntimeLayerReadModel& layer : input.runtimeLayers.displayLayers)
+	for (const SupportedShaderSummary& shader : shaderCatalog.Shaders())
 	{
-		const ShaderPackage* shaderPackage = input.shaderCatalog.FindPackage(layer.shaderId);
+		writer.BeginObject();
+		writer.KeyString("id", shader.id);
+		writer.KeyString("name", shader.name);
+		writer.KeyString("description", shader.description);
+		writer.KeyString("category", shader.category);
+		writer.KeyBool("available", true);
+		writer.KeyNull("error");
+		writer.EndObject();
+	}
+	writer.EndArray();
+}
+
+inline void WriteEmptyCatalogJson(JsonWriter& writer)
+{
+	writer.BeginArray();
+	writer.EndArray();
+}
+
+inline void WriteRuntimeShaderLayersJson(
+	JsonWriter& writer,
+	const SupportedShaderCatalog& shaderCatalog,
+	const RuntimeLayerModelSnapshot& runtimeLayers)
+{
+	writer.BeginArray();
+	for (const RuntimeLayerReadModel& layer : runtimeLayers.displayLayers)
+	{
+		const ShaderPackage* shaderPackage = shaderCatalog.FindPackage(layer.shaderId);
 		writer.BeginObject();
 		writer.KeyString("id", layer.id);
 		writer.KeyString("shaderId", layer.shaderId);
@@ -281,6 +327,12 @@ inline void WriteLayersJson(JsonWriter& writer, const RuntimeStateJsonInput& inp
 	writer.EndArray();
 }
 
+inline void WriteEmptyLayersJson(JsonWriter& writer)
+{
+	writer.BeginArray();
+	writer.EndArray();
+}
+
 inline void WriteOscJson(JsonWriter& writer, const RuntimeStateJsonInput& input)
 {
 	const bool configured = input.osc ? input.osc->configured : input.config.oscPort != 0;
@@ -343,11 +395,10 @@ inline std::string RuntimeStateToJson(const RuntimeStateJsonInput& input)
 	writer.EndObject();
 
 	writer.Key("runtime");
-	writer.BeginObject();
-	writer.KeyUInt("layerCount", static_cast<uint64_t>(input.runtimeLayers.displayLayers.size()));
-	writer.KeyBool("compileSucceeded", input.runtimeLayers.compileSucceeded);
-	writer.KeyString("compileMessage", input.runtimeLayers.compileMessage);
-	writer.EndObject();
+	if (input.writeRuntimeJson)
+		input.writeRuntimeJson(writer);
+	else
+		WriteEmptyRuntimeJson(writer);
 
 	writer.Key("video");
 	writer.BeginObject();
@@ -386,24 +437,18 @@ inline std::string RuntimeStateToJson(const RuntimeStateJsonInput& input)
 	writer.KeyNull("backendPlayout");
 	writer.KeyNull("runtimeEvents");
 	writer.Key("shaders");
-	writer.BeginArray();
-	for (const SupportedShaderSummary& shader : input.shaderCatalog.Shaders())
-	{
-		writer.BeginObject();
-		writer.KeyString("id", shader.id);
-		writer.KeyString("name", shader.name);
-		writer.KeyString("description", shader.description);
-		writer.KeyString("category", shader.category);
-		writer.KeyBool("available", true);
-		writer.KeyNull("error");
-		writer.EndObject();
-	}
-	writer.EndArray();
+	if (input.writeCatalogJson)
+		input.writeCatalogJson(writer);
+	else
+		WriteEmptyCatalogJson(writer);
 	writer.Key("stackPresets");
 	writer.BeginArray();
 	writer.EndArray();
 	writer.Key("layers");
-	WriteLayersJson(writer, input);
+	if (input.writeLayersJson)
+		input.writeLayersJson(writer);
+	else
+		WriteEmptyLayersJson(writer);
 
 	writer.EndObject();
 	return writer.StringValue();

tests/RenderCadenceCompositorRuntimeStateJsonTests.cpp

@@ -100,15 +100,24 @@ int main()
 	layerModel.MarkBuildReady(artifact, error);
 	const RenderCadenceCompositor::RuntimeLayerModelSnapshot layerSnapshot = layerModel.Snapshot();
 
-	const std::string json = RenderCadenceCompositor::RuntimeStateToJson(RenderCadenceCompositor::RuntimeStateJsonInput{
+	RenderCadenceCompositor::RuntimeStateJsonInput stateInput{
 		config,
 		telemetry,
 		8080,
 		true,
 		"DeckLink scheduled output running.",
-		shaderCatalog,
-		layerSnapshot
-	});
+		nullptr
+	};
+	stateInput.writeRuntimeJson = [&layerSnapshot](RenderCadenceCompositor::JsonWriter& writer) {
+		RenderCadenceCompositor::WriteShaderRuntimeJson(writer, layerSnapshot);
+	};
+	stateInput.writeCatalogJson = [&shaderCatalog](RenderCadenceCompositor::JsonWriter& writer) {
+		RenderCadenceCompositor::WriteShaderCatalogJson(writer, shaderCatalog);
+	};
+	stateInput.writeLayersJson = [&shaderCatalog, &layerSnapshot](RenderCadenceCompositor::JsonWriter& writer) {
+		RenderCadenceCompositor::WriteRuntimeShaderLayersJson(writer, shaderCatalog, layerSnapshot);
+	};
+	const std::string json = RenderCadenceCompositor::RuntimeStateToJson(stateInput);
 
 	ExpectContains(json, "\"shaders\":[{\"id\":\"solid-color\"", "state JSON should include supported shaders");
 	ExpectContains(json, "\"layerCount\":1", "state JSON should expose the display layer count");