[BUGFIX] Support no head key in WaveNet config

NAM/wavenet.cpp

@@ -820,7 +820,7 @@ std::unique_ptr<nam::DSP> nam::wavenet::Factory(const nlohmann::json& config, st
       input_mixin_pre_film_params, input_mixin_post_film_params, activation_pre_film_params,
       activation_post_film_params, _layer1x1_post_film_params, head1x1_post_film_params));
   }
-  const bool with_head = !config["head"].is_null();
+  const bool with_head = config.find("head") != config.end() && !config["head"].is_null();
   const float head_scale = config["head_scale"];
 
   if (layer_array_params.empty())

tools/run_tests.cpp

@@ -19,6 +19,7 @@
 #include "test/test_wavenet/test_condition_processing.cpp"
 #include "test/test_wavenet/test_head1x1.cpp"
 #include "test/test_wavenet/test_layer1x1.cpp"
+#include "test/test_wavenet/test_factory.cpp"
 #include "test/test_gating_activations.cpp"
 #include "test/test_wavenet_gating_compatibility.cpp"
 #include "test/test_blending_detailed.cpp"
@@ -169,6 +170,7 @@ int main()
   test_wavenet::test_layer1x1::test_layer1x1_post_film_inactive_with_layer1x1_inactive();
   test_wavenet::test_layer1x1::test_layer1x1_gated();
   test_wavenet::test_layer1x1::test_layer1x1_groups();
+  test_wavenet::test_factory::test_factory_without_head_key();
   test_wavenet::test_allocation_tracking_pass();
   test_wavenet::test_allocation_tracking_fail();
   test_wavenet::test_conv1d_process_realtime_safe();

tools/test/test_wavenet/test_factory.cpp

@@ -0,0 +1,73 @@
+// Tests for WaveNet Factory
+
+#include <cassert>
+#include <cmath>
+#include <memory>
+#include <vector>
+
+#include "json.hpp"
+
+#include "NAM/get_dsp.h"
+#include "NAM/wavenet.h"
+
+namespace test_wavenet
+{
+namespace test_factory
+{
+/// Asserts that the model is instantiated correctly when no "head" key is provided.
+/// The deprecated "head" key is optional; when absent, with_head should be false.
+void test_factory_without_head_key()
+{
+  // Minimal WaveNet config - deliberately omits the "head" key entirely.
+  // Same structure as wavenet.nam but without "head" in config.
+  const std::string configStr = R"({
+    "version": "0.5.4",
+    "metadata": {},
+    "architecture": "WaveNet",
+    "config": {
+      "layers": [{
+        "input_size": 1,
+        "condition_size": 1,
+        "head_size": 1,
+        "channels": 1,
+        "kernel_size": 1,
+        "dilations": [1],
+        "activation": "ReLU",
+        "gated": false,
+        "head_bias": false
+      }],
+      "head_scale": 1.0
+    },
+    "weights": [1.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0, 1.0],
+    "sample_rate": 48000
+  })";
+
+  nlohmann::json j = nlohmann::json::parse(configStr);
+
+  // Verify the config does not contain "head" key
+  assert(j["config"].find("head") == j["config"].end());
+
+  // Load model via get_dsp - exercises Factory path
+  std::unique_ptr<nam::DSP> dsp = nam::get_dsp(j);
+  assert(dsp != nullptr);
+
+  // Process audio to verify model works correctly
+  const int numFrames = 4;
+  const int maxBufferSize = 64;
+  dsp->Reset(48000.0, maxBufferSize);
+
+  std::vector<NAM_SAMPLE> input(numFrames, 1.0f);
+  std::vector<NAM_SAMPLE> output(numFrames, 0.0f);
+  NAM_SAMPLE* inputPtrs[] = {input.data()};
+  NAM_SAMPLE* outputPtrs[] = {output.data()};
+
+  dsp->process(inputPtrs, outputPtrs, numFrames);
+
+  assert(static_cast<int>(output.size()) == numFrames);
+  for (int i = 0; i < numFrames; i++)
+  {
+    assert(std::isfinite(output[i]));
+  }
+}
+}; // namespace test_factory
+}; // namespace test_wavenet