fix(filter): drop dead seed write, reorder VF checks, tidy per review

- Remove params.seed = m_InputValues->seed (dead write; rng is seeded directly)
- Add clarifying comment noting simulateMTR uses the rng, not SimulationParams::seed
- Remove unused #include <cmath> from MTRSim.cpp
- Move per-element VF range check (-13007) before sum check (-13003) so
  out-of-range values produce the precise diagnostic rather than the misleading
  sum message
- Remove redundant size/spacing/VF args.insertOrAssign calls in execute test
  that duplicated what MakeValidArgs already sets; keep seed overrides

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: imikejackson

src/MTRSim/Filters/Algorithms/MTRSim.cpp

@@ -7,7 +7,6 @@
 
 #include <fmt/format.h>
 
-#include <cmath>
 #include <exception>
 #include <random>
 #include <vector>
@@ -62,7 +61,7 @@ Result<> MTRSim::operator()()
   params.dz = m_InputValues->physicalSpacing[2];
   params.volumeFractions = m_InputValues->volumeFractions[0]; // 1 row
   params.thetaList = m_InputValues->thetaList;
-  params.seed = m_InputValues->seed;
+  // Note: simulateMTR is driven by the seeded rng passed below; SimulationParams::seed is not consulted.
 
   if(m_ShouldCancel)
   {

src/MTRSim/Filters/MTRSimFilter.cpp

@@ -152,6 +152,13 @@ IFilter::PreflightResult MTRSimFilter::preflightImpl(const DataStructure& dataSt
   {
     return {MakeErrorResult<OutputActions>(-13002, fmt::format("Volume Fraction must be 1 row x {} columns (one per ODF component).", numComponents))};
   }
+  for(double v : pVolumeFractions[0])
+  {
+    if(v < 0.0 || v > 1.0)
+    {
+      return {MakeErrorResult<OutputActions>(-13007, fmt::format("Each Volume Fraction value must be in the range [0, 1] (got {:.4f}).", v))};
+    }
+  }
   double vfSum = 0.0;
   for(double v : pVolumeFractions[0])
   {
@@ -161,13 +168,6 @@ IFilter::PreflightResult MTRSimFilter::preflightImpl(const DataStructure& dataSt
   {
     return {MakeErrorResult<OutputActions>(-13003, fmt::format("Volume Fraction values must sum to 1.0 (got {:.4f}).", vfSum))};
   }
-  for(double v : pVolumeFractions[0])
-  {
-    if(v < 0.0 || v > 1.0)
-    {
-      return {MakeErrorResult<OutputActions>(-13007, fmt::format("Each Volume Fraction value must be in the range [0, 1] (got {:.4f}).", v))};
-    }
-  }
   if(pThetaList.size() < numComponents - 1)
   {
     return {MakeErrorResult<OutputActions>(-13004, fmt::format("Theta List needs at least {} rows (components - 1).", numComponents - 1))};

test/MTRSimTest.cpp

@@ -133,10 +133,7 @@ TEST_CASE("MTRSim::MTRSimFilter: Execute wires simulation to output arrays", "[M
 
   MTRSimFilter filter;
   Arguments args = MakeValidArgs(compPaths);
-  // Modest domain: 100x100 = 10000 voxels (Z=0 -> single layer).
-  args.insertOrAssign(MTRSimFilter::k_PhysicalSize_Key, std::vector<float32>{2.0f, 2.0f, 0.0f});
-  args.insertOrAssign(MTRSimFilter::k_PhysicalSpacing_Key, std::vector<float32>{0.02f, 0.02f, 0.02f});
-  args.insertOrAssign(MTRSimFilter::k_VolumeFractions_Key, DynamicTableParameter::ValueType{{0.30, 0.35, 0.35}});
+  // size/spacing/VF come from MakeValidArgs (100x100 grid)
   args.insertOrAssign(MTRSimFilter::k_UseSeed_Key, true);
   args.insertOrAssign(MTRSimFilter::k_SeedValue_Key, static_cast<uint64>(42));