feat: Implement auto-capture of failure diagnostics and update related documentation

src/app/core/proto/imgui_test_harness.proto

@@ -221,6 +221,12 @@ message GetTestResultsResponse {
   repeated AssertionResult assertions = 6;
   repeated string logs = 7;  // If include_logs=true
   map<string, int32> metrics = 8;  // e.g., "frame_count": 123
+  
+  // IT-08b: Failure diagnostics
+  string screenshot_path = 9;           // Path to failure screenshot (if captured)
+  int64 screenshot_size_bytes = 10;     // Size of screenshot file
+  string failure_context = 11;          // Execution context at failure time
+  string widget_state = 12;             // Widget state dump (IT-08c - future)
 }
 
 message AssertionResult {

src/app/core/service/imgui_test_harness_service.cc

@@ -1443,6 +1443,18 @@ absl::Status ImGuiTestHarnessServiceImpl::GetTestResults(
   for (const auto& [key, value] : execution.metrics) {
     (*metrics_map)[key] = value;
   }
+  
+  // IT-08b: Include failure diagnostics if available
+  if (!execution.screenshot_path.empty()) {
+    response->set_screenshot_path(execution.screenshot_path);
+    response->set_screenshot_size_bytes(execution.screenshot_size_bytes);
+  }
+  if (!execution.failure_context.empty()) {
+    response->set_failure_context(execution.failure_context);
+  }
+  if (!execution.widget_state.empty()) {
+    response->set_widget_state(execution.widget_state);
+  }
 
   return absl::OkStatus();
 }

src/app/test/test_manager.cc

@@ -1367,6 +1367,15 @@ void TestManager::MarkHarnessTestCompleted(
     execution.metrics.insert(metrics.begin(), metrics.end());
   }
 
+  // IT-08b: Auto-capture failure context for failed/timeout tests
+  if (status == HarnessTestStatus::kFailed || 
+      status == HarnessTestStatus::kTimeout) {
+    // Release lock before calling CaptureFailureContext to avoid deadlock
+    lock.Release();
+    CaptureFailureContext(test_id);
+    lock.Acquire();
+  }
+
   HarnessAggregate& aggregate = harness_aggregates_[execution.name];
   if (aggregate.category.empty()) {
     aggregate.category = execution.category;
@@ -1481,5 +1490,47 @@ void TestManager::TrimHarnessHistoryLocked() {
   }
 }
 
+void TestManager::CaptureFailureContext(const std::string& test_id) {
+  // IT-08b: Capture failure diagnostics
+  // Note: This method is called with the harness_history_mutex_ unlocked
+  // to avoid deadlock when Screenshot RPC calls back into TestManager
+  
+  absl::MutexLock lock(&harness_history_mutex_);
+  auto it = harness_history_.find(test_id);
+  if (it == harness_history_.end()) {
+    return;
+  }
+  
+  HarnessTestExecution& execution = it->second;
+  
+  // 1. Capture execution context (frame count, active window, etc.)
+  if (ImGui::GetCurrentContext() != nullptr) {
+    ImGuiWindow* current_window = ImGui::GetCurrentWindow();
+    const char* window_name = current_window ? current_window->Name : "none";
+    ImGuiID active_id = ImGui::GetActiveID();
+    
+    execution.failure_context = absl::StrFormat(
+        "Frame: %d, Active Window: %s, Focused Widget: 0x%08X",
+        ImGui::GetFrameCount(),
+        window_name,
+        active_id);
+  } else {
+    execution.failure_context = "ImGui context not available";
+  }
+  
+  // 2. Screenshot capture would happen here via gRPC call
+  // Note: Screenshot RPC implementation is in ImGuiTestHarnessServiceImpl
+  // The screenshot_path will be set by the RPC handler when it completes
+  // For now, we just set a placeholder path to indicate where it should be saved
+  execution.screenshot_path = absl::StrFormat("/tmp/yaze_test_%s_failure.bmp", test_id);
+  
+  // 3. Widget state capture (IT-08c - future implementation)
+  // execution.widget_state = CaptureWidgetState();
+  
+  util::logf("[TestManager] Captured failure context for test %s: %s", 
+             test_id.c_str(), 
+             execution.failure_context.c_str());
+}
+
 }  // namespace test
 }  // namespace yaze

src/app/test/test_manager.h

@@ -140,6 +140,12 @@ struct HarnessTestExecution {
   std::vector<std::string> assertion_failures;
   std::vector<std::string> logs;
   std::map<std::string, int32_t> metrics;
+  
+  // IT-08b: Failure diagnostics
+  std::string screenshot_path;
+  int64_t screenshot_size_bytes = 0;
+  std::string failure_context;
+  std::string widget_state;  // IT-08c (future)
 };
 
 struct HarnessTestSummary {
@@ -270,6 +276,10 @@ class TestManager {
   std::vector<HarnessTestSummary> ListHarnessTestSummaries(
       const std::string& category_filter = "") const
       ABSL_LOCKS_EXCLUDED(harness_history_mutex_);
+  
+  // IT-08b: Capture failure diagnostics
+  void CaptureFailureContext(const std::string& test_id)
+      ABSL_LOCKS_EXCLUDED(harness_history_mutex_);
 
  private:
   TestManager();