feat: Add dual-mode dictation (walkie-talkie + continuous)

- Press and hold: walkie-talkie mode, records while held, transcribes on release
- Double-click: continuous mode (existing behavior), click again to stop
- Uses Dear PyGui item handlers for mouse down/up detection
- Visual feedback shows current mode on button label

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/discussions/ui/gui.py

@@ -409,13 +409,76 @@ class DiscussionGUI:
             if dpg.does_item_exist(button_tag):
                 dpg.set_item_label(button_tag, "Read")
 
-    def _dictate_clicked(self):
+    def _on_dictate_activated(self, sender, app_data):
-        """Handle dictate button click - toggle recording."""
+        """Handle mouse down on dictate button - start timing for mode detection."""
+        import time
+
+        current_time = time.time()
+
+        # Check for double-click (two clicks within 300ms)
+        if current_time - self._last_dictate_click_time < 0.3:
+            # Double-click detected
+            self._last_dictate_click_time = 0  # Reset to prevent triple-click issues
+            self._dictation_mode = "continuous"
+            self._start_dictation()
+            return
+
+        self._last_dictate_click_time = current_time
+        self._mouse_down_time = current_time
+
+        # If we're in continuous mode, a click should stop it
+        if self._dictation_mode == "continuous":
+            self._stop_dictation()
+            self._dictation_mode = "idle"
+            return
+
+        # Start push-to-talk mode preparation
+        # We'll confirm it in deactivated if held long enough
+        self._dictation_mode = "push_to_talk_pending"
+
+        # Update button visual to show it's being pressed
+        if dpg.does_item_exist("dictate_btn"):
+            dpg.set_item_label("dictate_btn", "● Hold...")
+
+    def _on_dictate_deactivated(self, sender, app_data):
+        """Handle mouse up on dictate button - determine action based on hold duration."""
+        import time
+
+        current_time = time.time()
+        hold_duration = current_time - getattr(self, '_mouse_down_time', current_time)
+
+        if self._dictation_mode == "push_to_talk_pending":
+            if hold_duration > 0.2:  # Held for more than 200ms - it was push-to-talk
+                # Button was held down, treat as walkie-talkie release
+                self._dictation_mode = "idle"
                 if self._continuous_recorder is not None:
-            # Currently recording - stop
                     self._stop_dictation()
                 else:
-            # Start recording
+                    # Was just a long press but recording didn't start yet
+                    if dpg.does_item_exist("dictate_btn"):
+                        dpg.set_item_label("dictate_btn", "Dictate")
+            else:
+                # Short click - wait for potential double-click
+                self._dictation_mode = "idle"
+                if dpg.does_item_exist("dictate_btn"):
+                    dpg.set_item_label("dictate_btn", "Dictate")
+        elif self._dictation_mode == "push_to_talk":
+            # Release from push-to-talk mode - stop recording
+            self._dictation_mode = "idle"
+            self._stop_dictation()
+        # continuous mode is handled by click, not release
+
+    def _on_dictate_active(self, sender, app_data):
+        """Handle button being held down - start push-to-talk recording after threshold."""
+        import time
+
+        current_time = time.time()
+        hold_duration = current_time - getattr(self, '_mouse_down_time', current_time)
+
+        if self._dictation_mode == "push_to_talk_pending" and hold_duration > 0.2:
+            # Held long enough - start push-to-talk recording
+            self._dictation_mode = "push_to_talk"
+            if self._continuous_recorder is None:
                 self._start_dictation()
 
     def _start_dictation(self):
@@ -431,9 +494,12 @@ class DiscussionGUI:
 
         self._continuous_recorder.start()
 
-        # Update button to show recording state
+        # Update button to show recording state based on mode
         if dpg.does_item_exist("dictate_btn"):
-            dpg.set_item_label("dictate_btn", "● Recording...")
+            if self._dictation_mode == "continuous":
+                dpg.set_item_label("dictate_btn", "● Continuous (click to stop)")
+            else:  # push_to_talk
+                dpg.set_item_label("dictate_btn", "● Recording (release to stop)")
 
     def _stop_dictation(self):
         """Stop recording and transcribe any remaining audio."""
@@ -556,6 +622,12 @@ class DiscussionGUI:
         self._transcription_queue = []  # Queue of transcription results
         self._transcription_lock = threading.Lock()
 
+        # Dictation mode tracking for press-and-hold vs double-click
+        self._dictation_mode = "idle"  # "idle", "push_to_talk", "push_to_talk_pending", "continuous"
+        self._last_dictate_click_time = 0.0
+        self._mouse_down_time = 0.0
+        self._push_to_talk_thread: Optional[threading.Thread] = None
+
         # Initialize Dear PyGui
         dpg.create_context()
         dpg.create_viewport(title="Orchestrated Discussions", width=1400, height=900)
@@ -1918,6 +1990,11 @@ class DiscussionGUI:
         window_tag = "comment_dialog"
         if dpg.does_item_exist(window_tag):
             dpg.delete_item(window_tag)
+        if dpg.does_item_exist("dictate_btn_handlers"):
+            dpg.delete_item("dictate_btn_handlers")
+        # Reset dictation state when dialog opens
+        self._dictation_mode = "idle"
+        self._last_dictate_click_time = 0.0
 
         with dpg.window(label="Add Comment", tag=window_tag, modal=True,
                        width=600, height=400, pos=[400, 200]):
@@ -1928,9 +2005,14 @@ class DiscussionGUI:
                 dpg.add_button(
                     label="Dictate",
                     tag="dictate_btn",
-                    callback=lambda: self._dictate_clicked(),
                     width=100
                 )
+                # Add item handlers for press-and-hold vs double-click detection
+                with dpg.item_handler_registry(tag="dictate_btn_handlers"):
+                    dpg.add_item_activated_handler(callback=self._on_dictate_activated)
+                    dpg.add_item_deactivated_handler(callback=self._on_dictate_deactivated)
+                    dpg.add_item_active_handler(callback=self._on_dictate_active)
+                dpg.bind_item_handler_registry("dictate_btn", "dictate_btn_handlers")
                 dpg.add_button(
                     label="Add Artifact",
                     callback=lambda: self._launch_artifact_editor_for_comment(),