feat(tests): Add boundary tests, model error messages, gitattributes

- Add model file existence check and ONNX error output in gunshot_classifier
- Add 3 new unit tests to test_core_lib:
  - audio_buffer_overflow: verifies capacity capping behavior
  - distance_estimator_multi_class: verifies gunshot/artillery/explosion refs
  - threat_tracker_filtering: verifies min_event_interval deduplication
- Add .gitattributes to mark .onnx, .bin, .wav as binary files
- All 9 core tests pass

src/drone-software/src/acoustic/.gitattributes

@@ -0,0 +1,4 @@
+# Mark binary files
+*.onnx binary
+*.bin binary
+*.wav binary

src/drone-software/src/acoustic/src/core/gunshot_classifier.cpp

@@ -104,6 +104,14 @@ struct GunshotClassifier::Impl {
     }
 
     bool LoadModel(const std::string& path) {
+        // Verify file exists before attempting ONNX load
+        std::ifstream check(path, std::ios::binary);
+        if (!check) {
+            std::cerr << "[ERROR] Model file not found: " << path << std::endl;
+            return false;
+        }
+        check.close();
+
 #ifdef _WIN32
         int wlen = MultiByteToWideChar(CP_UTF8, 0, path.c_str(), -1, nullptr, 0);
         std::wstring wpath;
@@ -114,14 +122,14 @@ struct GunshotClassifier::Impl {
         try {
             session = std::make_unique<Ort::Session>(env, wpath.c_str(), *session_options);
         } catch (const Ort::Exception& e) {
-            (void)e;
+            std::cerr << "[ERROR] ONNX Runtime failed to load model: " << e.what() << std::endl;
             return false;
         }
 #else
         try {
             session = std::make_unique<Ort::Session>(env, path.c_str(), *session_options);
         } catch (const Ort::Exception& e) {
-            (void)e;
+            std::cerr << "[ERROR] ONNX Runtime failed to load model: " << e.what() << std::endl;
             return false;
         }
 #endif

src/drone-software/src/acoustic/tests/test_core_lib.cpp

@@ -109,13 +109,61 @@ void test_feature_extractor_shape() {
     std::cout << "[PASS] feature_extractor_shape (" << mel.rows() << " x " << mel.cols() << ")" << std::endl;
 }
 
+void test_audio_buffer_overflow() {
+    AudioBuffer buf(10, 1);
+    std::vector<float> data(25, 1.0f);
+    buf.Push(data);
+    assert(buf.Size() == 10); // should cap at capacity
+    auto popped = buf.Pop(5);
+    assert(popped.size() == 5);
+    assert(buf.Size() == 5);
+    std::cout << "[PASS] audio_buffer_overflow" << std::endl;
+}
+
+void test_distance_estimator_multi_class() {
+    DistanceConfig config;
+    config.ref_spl_gunshot = 150.0f;
+    config.ref_spl_artillery = 180.0f;
+    config.ref_spl_explosion = 170.0f;
+    config.attenuation_alpha = 0.6f;
+    DistanceEstimator est(config);
+    float d1 = est.Estimate(120.0f, "gunshot");
+    float d2 = est.Estimate(120.0f, "artillery");
+    float d3 = est.Estimate(120.0f, "explosion");
+    assert(d2 > d1); // artillery has higher ref SPL -> farther estimated distance at same SPL
+    assert(d3 > d1);
+    std::cout << "[PASS] distance_estimator_multi_class" << std::endl;
+}
+
+void test_threat_tracker_filtering() {
+    ThreatTracker tracker(0.3f, 15.0f, 5);
+    AcousticThreat t1;
+    t1.sound_type = "gunshot";
+    t1.confidence = 0.9f;
+    t1.azimuth = 45.0f;
+    t1.distance = 100.0f;
+
+    // First update should publish
+    auto out1 = tracker.Update({t1});
+    assert(out1.size() == 1);
+
+    // Immediate second update with same azimuth should be filtered (interval < 0.3s)
+    auto out2 = tracker.Update({t1});
+    assert(out2.empty());
+
+    std::cout << "[PASS] threat_tracker_filtering" << std::endl;
+}
+
 int main() {
     std::cout << "Running core library tests..." << std::endl;
     test_audio_buffer();
+    test_audio_buffer_overflow();
     test_preemphasis();
     test_gcc_phat_cross_array();
     test_distance_estimator();
+    test_distance_estimator_multi_class();
     test_threat_tracker();
+    test_threat_tracker_filtering();
     test_feature_extractor_shape();
     std::cout << "All tests passed!" << std::endl;
     return 0;