feat: Implement screenshot capture functionality for specific regions and active windows in screenshot_utils

- Added CaptureHarnessScreenshotRegion function to capture a specified region of the renderer output.
- Introduced CaptureActiveWindow and CaptureWindowByName functions to capture screenshots of the currently active ImGui window or a specific window by name.
- Updated screenshot_utils.h to include new CaptureRegion struct and corresponding function declarations.
- Enhanced EditorManager to utilize the new capture modes based on user selection in the AgentChatWidget.

src/app/editor/system/agent_chat_history_codec.cc

@@ -27,8 +27,8 @@ absl::Time ParseTimestamp(const Json& value) {
     return absl::Now();
   }
   absl::Time parsed;
-  if (absl::ParseTime(absl::RFC3339_full, value.get<std::string>(),
-                      absl::UTCTimeZone(), &parsed)) {
+  if (absl::ParseTime(absl::RFC3339_full, value.get<std::string>(), &parsed,
+                      nullptr)) {
     return parsed;
   }
   return absl::Now();

src/app/editor/system/agent_chat_widget.cc

@@ -484,6 +484,9 @@ void AgentChatWidget::Draw() {
   }
 
   EnsureHistoryLoaded();
+  
+  // Poll for new messages in collaborative sessions
+  PollSharedHistory();
 
   ImGui::Begin(title_.c_str(), &active_);
   RenderHistory();
@@ -668,8 +671,31 @@ void AgentChatWidget::RenderMultimodalPanel() {
   bool can_capture = static_cast<bool>(multimodal_callbacks_.capture_snapshot);
   bool can_send = static_cast<bool>(multimodal_callbacks_.send_to_gemini);
 
+  // Capture mode selection
+  ImGui::Text("Capture Mode:");
+  ImGui::RadioButton("Full Window", 
+      reinterpret_cast<int*>(&multimodal_state_.capture_mode), 
+      static_cast<int>(CaptureMode::kFullWindow));
+  ImGui::SameLine();
+  ImGui::RadioButton("Active Editor", 
+      reinterpret_cast<int*>(&multimodal_state_.capture_mode), 
+      static_cast<int>(CaptureMode::kActiveEditor));
+  ImGui::SameLine();
+  ImGui::RadioButton("Specific Window", 
+      reinterpret_cast<int*>(&multimodal_state_.capture_mode), 
+      static_cast<int>(CaptureMode::kSpecificWindow));
+
+  // If specific window mode, show input for window name
+  if (multimodal_state_.capture_mode == CaptureMode::kSpecificWindow) {
+    ImGui::InputText("Window Name", multimodal_state_.specific_window_buffer,
+                     IM_ARRAYSIZE(multimodal_state_.specific_window_buffer));
+    ImGui::TextDisabled("Examples: Overworld Editor, Dungeon Editor, Sprite Editor");
+  }
+
+  ImGui::Separator();
+
   if (!can_capture) ImGui::BeginDisabled();
-  if (ImGui::Button("Capture Map Snapshot")) {
+  if (ImGui::Button("Capture Snapshot")) {
     if (multimodal_callbacks_.capture_snapshot) {
       std::filesystem::path captured_path;
       absl::Status status =
@@ -822,6 +848,10 @@ void AgentChatWidget::SwitchToSharedHistory(const std::string& session_id) {
   // Load shared history
   EnsureHistoryLoaded();
   
+  // Initialize polling state
+  last_known_history_size_ = agent_service_.GetHistory().size();
+  last_shared_history_poll_ = absl::Now();
+  
   if (toast_manager_) {
     toast_manager_->Show(
         absl::StrFormat("Switched to shared chat history for session %s",
@@ -849,5 +879,44 @@ void AgentChatWidget::SwitchToLocalHistory() {
   }
 }
 
+void AgentChatWidget::PollSharedHistory() {
+  if (!collaboration_state_.active) {
+    return;  // Not in a collaborative session
+  }
+
+  const absl::Time now = absl::Now();
+  
+  // Poll every 2 seconds
+  if (now - last_shared_history_poll_ < absl::Seconds(2)) {
+    return;
+  }
+  
+  last_shared_history_poll_ = now;
+
+  // Check if the shared history file has been updated
+  auto result = AgentChatHistoryCodec::Load(history_path_);
+  if (!result.ok()) {
+    return;  // File might not exist yet or be temporarily locked
+  }
+
+  const size_t new_size = result->history.size();
+  
+  // If history has grown, reload it
+  if (new_size > last_known_history_size_) {
+    const size_t new_messages = new_size - last_known_history_size_;
+    
+    agent_service_.ReplaceHistory(std::move(result->history));
+    last_history_size_ = new_size;
+    last_known_history_size_ = new_size;
+    
+    if (toast_manager_) {
+      toast_manager_->Show(
+          absl::StrFormat("📬 %zu new message%s from collaborators",
+                          new_messages, new_messages == 1 ? "" : "s"),
+          ToastType::kInfo, 3.0f);
+    }
+  }
+}
+
 }  // namespace editor
 }  // namespace yaze

src/app/editor/system/agent_chat_widget.h

@@ -62,11 +62,6 @@ class AgentChatWidget {
   bool* active() { return &active_; }
   bool is_active() const { return active_; }
   void set_active(bool active) { active_ = active; }
-  
-  CaptureMode capture_mode() const { return multimodal_state_.capture_mode; }
-  const char* specific_window_name() const { 
-    return multimodal_state_.specific_window_buffer; 
-  }
 
 public:
   struct CollaborationState {
@@ -91,10 +86,19 @@ public:
     char specific_window_buffer[128] = {};
   };
 
-  void EnsureHistoryLoaded();
-  void PersistHistory();
+  // Accessors for capture settings
+  CaptureMode capture_mode() const { return multimodal_state_.capture_mode; }
+  const char* specific_window_name() const { 
+    return multimodal_state_.specific_window_buffer; 
+  }
+
+  // Collaboration history management (public so EditorManager can call them)
   void SwitchToSharedHistory(const std::string& session_id);
   void SwitchToLocalHistory();
+
+ private:
+  void EnsureHistoryLoaded();
+  void PersistHistory();
   void RenderHistory();
   void RenderMessage(const cli::agent::ChatMessage& msg, int index);
   void RenderProposalQuickActions(const cli::agent::ChatMessage& msg,