diff --git a/stimBuffApis/livoxGen1/openClCollatingAndMeshingEngine.cpp b/stimBuffApis/livoxGen1/openClCollatingAndMeshingEngine.cpp
index d0fd3d5..6cd1f5b 100644
--- a/stimBuffApis/livoxGen1/openClCollatingAndMeshingEngine.cpp
+++ b/stimBuffApis/livoxGen1/openClCollatingAndMeshingEngine.cpp
@@ -30,7 +30,8 @@ currentKernelEvent(nullptr),
 assemblyBufferPtr(nullptr),
 assemblyBufferSize(0),
 collationBufferPtr(nullptr),
-collationBufferSize(0)
+collationBufferSize(0),
+frameAssemblyDesc(nullptr)
 {
 }
 
@@ -100,6 +101,16 @@ bool OpenClCollatingAndMeshingEngine::setup()
 	collationBufferPtr = collationIov.iov_base;
 	collationBufferSize = collationIov.iov_len;
 
+	// Get FrameAssemblyDesc from assembly buffer
+	frameAssemblyDesc = static_cast<std::shared_ptr<FrameAssemblyDesc>>(
+		parent.assemblyBuffer);
+
+	if (!frameAssemblyDesc || frameAssemblyDesc->slots.empty())
+	{
+		std::cerr << __func__ << ": invalid frame descriptor" << std::endl;
+		goto cleanup;
+	}
+
 	// Create OpenCL buffers using CL_MEM_USE_HOST_PTR for zero-copy
 	clAssemblyBuffer = clCreateBuffer(
 		context,
@@ -206,6 +217,7 @@ void OpenClCollatingAndMeshingEngine::finalize()
 	assemblyBufferSize = 0;
 	collationBufferPtr = nullptr;
 	collationBufferSize = 0;
+	frameAssemblyDesc = nullptr;
 }
 
 // Static callback for OpenCL event
@@ -226,7 +238,7 @@ void CL_CALLBACK OpenClCollatingAndMeshingEngine::kernelEventCallback(
 	}
 }
 
-void OpenClCollatingAndMeshingEngine::start(
+bool OpenClCollatingAndMeshingEngine::start(
 	StagingBuffer& assemblyBuff, StagingBuffer& collationBuff,
 	collateFrameReqCbFn callback,
 	uint32_t nSucceeded)
@@ -234,14 +246,14 @@ void OpenClCollatingAndMeshingEngine::start(
 	if (!isSetup)
 	{
 		std::cerr << __func__ << ": engine not set up" << std::endl;
-		return;
+		return false;
 	}
 
 	if (isRunning)
 	{
 		std::cerr << __func__ << ": already running, call stop() first"
 			<< std::endl;
-		return;
+		return false;
 	}
 
 	// Validate buffers match what we set up
@@ -249,38 +261,24 @@ void OpenClCollatingAndMeshingEngine::start(
 	struct iovec collationIov = collationBuff.getClEngineIovec();
 
 	if (assemblyIov.iov_base != assemblyBufferPtr
-		|| assemblyIov.iov_len != assemblyBufferSize)
-	{
-		std::cerr << __func__ << ": assembly buffer mismatch" << std::endl;
-		return;
-	}
-
-	if (collationIov.iov_base != collationBufferPtr
+		|| assemblyIov.iov_len != assemblyBufferSize
+		|| collationIov.iov_base != collationBufferPtr
 		|| collationIov.iov_len != collationBufferSize)
 	{
-		std::cerr << __func__ << ": collation buffer mismatch" << std::endl;
-		return;
+		throw std::runtime_error(
+			std::string(__func__) + ": buffer mismatch - buffers have changed");
 	}
 
 	// Store the caller's callback
 	collateFrameReqCb = callback;
 
-	// Get FrameAssemblyDesc from assembly buffer
-	std::shared_ptr<FrameAssemblyDesc> frameDesc =
-		static_cast<std::shared_ptr<FrameAssemblyDesc>>(assemblyBuff);
-	if (!frameDesc || frameDesc->slots.empty())
-	{
-		std::cerr << __func__ << ": invalid frame descriptor" << std::endl;
-		return;
-	}
-
 	// Set up kernel arguments for slotCompactor
 	if (!setupSlotCompactorsArgs(assemblyBuff, nSucceeded)) {
-		return;
+		return false;
 	}
 	// Set up kernel arguments for collateDgrams
 	if (!setupCollateDgramsArgs(assemblyBuff)) {
-		return;
+		return false;
 	}
 
 	// Enqueue slotCompactor kernel execution (single work item for sequential processing)
@@ -293,7 +291,7 @@ void OpenClCollatingAndMeshingEngine::start(
 	{
 		std::cerr << __func__ << ": failed to enqueue slotCompactor kernel: "
 			<< err << std::endl;
-		return;
+		return false;
 	}
 
 	// Set up callback using static member function
@@ -310,7 +308,7 @@ void OpenClCollatingAndMeshingEngine::start(
 			<< std::endl;
 		clReleaseEvent(currentKernelEvent);
 		currentKernelEvent = nullptr;
-		return;
+		return false;
 	}
 
 	// TODO: Set up timeout timer in continuation class
@@ -319,6 +317,7 @@ void OpenClCollatingAndMeshingEngine::start(
 	isRunning = true;
 	// start() is synchronous - it returns immediately after setting up kernel execution
 	// The callback will be invoked when the kernel completes
+	return true;
 }
 
 bool OpenClCollatingAndMeshingEngine::compileAndPrepareKernel(
@@ -398,19 +397,10 @@ bool OpenClCollatingAndMeshingEngine::compileAndPrepareKernels()
 bool OpenClCollatingAndMeshingEngine::setupSlotCompactorsArgs(
 	StagingBuffer& assemblyBuff, uint32_t nSucceeded)
 {
-	// Get FrameAssemblyDesc from assembly buffer
-	std::shared_ptr<FrameAssemblyDesc> frameDesc =
-		static_cast<std::shared_ptr<FrameAssemblyDesc>>(assemblyBuff);
-	if (!frameDesc || frameDesc->slots.empty())
-	{
-		std::cerr << __func__ << ": invalid frame descriptor" << std::endl;
-		return false;
-	}
-
 	// Extract parameters for slotCompactor kernel
-	uint32_t numSlots = static_cast<uint32_t>(frameDesc->numSlots);
+	uint32_t numSlots = static_cast<uint32_t>(frameAssemblyDesc->numSlots);
 	uint32_t slotStride = static_cast<uint32_t>(assemblyBuff.slotStrideNBytes);
-	uint32_t slotSize = static_cast<uint32_t>(frameDesc->slotSizeBytes);
+	uint32_t slotSize = static_cast<uint32_t>(frameAssemblyDesc->slotSizeBytes);
 	uint32_t firstSlotOffset = static_cast<uint32_t>(
 		assemblyBuff.firstSlotOffsetNBytes);
 	uint32_t nSucceededUint = static_cast<uint32_t>(nSucceeded);
@@ -477,15 +467,6 @@ bool OpenClCollatingAndMeshingEngine::setupSlotCompactorsArgs(
 bool OpenClCollatingAndMeshingEngine::setupCollateDgramsArgs(
 	StagingBuffer& assemblyBuff)
 {
-	// Get FrameAssemblyDesc from assembly buffer
-	std::shared_ptr<FrameAssemblyDesc> frameDesc =
-		static_cast<std::shared_ptr<FrameAssemblyDesc>>(assemblyBuff);
-	if (!frameDesc || frameDesc->slots.empty())
-	{
-		std::cerr << __func__ << ": invalid frame descriptor" << std::endl;
-		return false;
-	}
-
 	// Extract parameters for collateDgrams kernel
 	uint32_t slotStride = static_cast<uint32_t>(assemblyBuff.slotStrideNBytes);
 	uint32_t firstSlotOffset = static_cast<uint32_t>(
@@ -500,7 +481,8 @@ bool OpenClCollatingAndMeshingEngine::setupCollateDgramsArgs(
 	int returnMode = static_cast<int>(parent.device->currentReturnMode);
 	uint32_t nPointsPerSlot = static_cast<uint32_t>(
 		IoUringAssemblyEngine::computePointsPerDgram(returnMode));
-	uint32_t nDgramsPerFrame = static_cast<uint32_t>(frameDesc->numSlots);
+	uint32_t nDgramsPerFrame = static_cast<uint32_t>(
+		frameAssemblyDesc->numSlots);
 
 	// Set kernel arguments for collateDgrams
 	cl_int err;
diff --git a/stimBuffApis/livoxGen1/openClCollatingAndMeshingEngine.h b/stimBuffApis/livoxGen1/openClCollatingAndMeshingEngine.h
index c06cdce..4648b60 100644
--- a/stimBuffApis/livoxGen1/openClCollatingAndMeshingEngine.h
+++ b/stimBuffApis/livoxGen1/openClCollatingAndMeshingEngine.h
@@ -9,6 +9,7 @@
 #define CL_TARGET_OPENCL_VERSION 300
 #include <CL/cl.h>
 #include "stagingBuffer.h"
+#include "frameAssemblyDesc.h"
 
 namespace smo {
 namespace stim_buff {
@@ -37,7 +38,7 @@ public:
 	// Callback function type for collateFrameReq
 	typedef std::function<void()> collateFrameReqCbFn;
 
-	void start(
+	bool start(
 		StagingBuffer& assemblyBuff, StagingBuffer& collationBuff,
 		collateFrameReqCbFn callback,
 		uint32_t nSucceeded);
@@ -71,6 +72,9 @@ private:
 	void* collationBufferPtr;
 	size_t collationBufferSize;
 
+	// Frame descriptor (cached from setup)
+	std::shared_ptr<FrameAssemblyDesc> frameAssemblyDesc;
+
 	// Callback storage
 	collateFrameReqCbFn collateFrameReqCb;