fix: eliminate QTextCursor cross-thread signal warning on inference stop

Three related fixes to the QObject::connect / QTextCursor warning that
appeared when stopping inference:

1. StdoutCapture: replace signal emission with queue.Queue.put_nowait()
   so non-Qt SDK threads (Kneron shutdown) never touch Qt signal machinery.
   DeploymentWorker.stdout_captured signal removed; worker now accepts a
   stdout_queue and passes it to StdoutCapture.

2. start_deployment: create QTimer (100 ms) on main thread to drain the
   stdout queue via _drain_stdout_queue(). Connect worker.finished to
   _on_worker_finished to stop the timer and flush remaining output.

3. stop_deployment / wait_for_stop: the background thread was calling
   QTextEdit.append() and other widget methods directly, which internally
   creates QTextCursor queued connections — the real trigger of the
   warning. Fixed by having wait_for_stop emit _stop_done signal only;
   all UI updates moved to _on_stop_done slot (main thread).

Also adds QTextCursor import in main.py to pre-register the type with
Qt's meta-type system as a belt-and-suspenders measure.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

main.py

@@ -23,7 +23,7 @@ import sys
 import os
 import tempfile
 from PyQt5.QtWidgets import QApplication, QMessageBox
-from PyQt5.QtGui import QFont
+from PyQt5.QtGui import QFont, QTextCursor  # QTextCursor import registers it with Qt meta-type system
 from PyQt5.QtCore import Qt, QSharedMemory, QCoreApplication
 
 # Import fcntl only on Unix-like systems

ui/dialogs/deployment.py

@@ -21,6 +21,7 @@ Usage:
 import os
 import sys
 import json
+import queue
 import threading
 import traceback
 import io
@@ -59,54 +60,48 @@ except ImportError as e:
 
 
 class StdoutCapture:
-    """Context manager to capture stdout/stderr and emit to signal."""
+    """Context manager to capture stdout/stderr into a thread-safe queue.
 
-    def __init__(self, signal_emitter):
-        self.signal_emitter = signal_emitter
+    Uses queue.Queue instead of directly emitting a Qt signal, so that
+    any thread (including non-Qt SDK threads) can safely write output
+    without triggering cross-thread signal warnings.
+    The dialog drains the queue from the main thread via QTimer.
+    """
+
+    def __init__(self, output_queue: queue.Queue):
+        self.output_queue = output_queue
         self.original_stdout = None
         self.original_stderr = None
-        self.captured_output = io.StringIO()
 
     def __enter__(self):
         self.original_stdout = sys.stdout
         self.original_stderr = sys.stderr
 
-        # Create a custom write function that both prints to original and captures
+        output_queue = self.output_queue
+
         class TeeWriter:
-            def __init__(self, original, captured, emitter):
+            def __init__(self, original):
                 self.original = original
-                self.captured = captured
-                self.emitter = emitter
-                self._emitting = False  # Prevent recursion
 
             def write(self, text):
-                # Write to original stdout/stderr (so it still appears in terminal)
-                # Check if original exists (it might be None in PyInstaller builds)
                 if self.original is not None:
                     self.original.write(text)
                     self.original.flush()
-                
-                # Capture for GUI if it's a substantial message and not already emitting
-                if text.strip() and not self._emitting:
-                    self._emitting = True
+                if text.strip():
                     try:
-                        self.emitter(text)
-                    finally:
-                        self._emitting = False
+                        output_queue.put_nowait(text)
+                    except queue.Full:
+                        pass  # Drop if queue full; non-fatal
 
             def flush(self):
-                # Check if original exists before calling flush
                 if self.original is not None:
                     self.original.flush()
 
-        # Replace stdout and stderr with our tee writers
-        sys.stdout = TeeWriter(self.original_stdout, self.captured_output, self.signal_emitter)
-        sys.stderr = TeeWriter(self.original_stderr, self.captured_output, self.signal_emitter)
-        
+        sys.stdout = TeeWriter(self.original_stdout)
+        sys.stderr = TeeWriter(self.original_stderr)
         return self
 
     def __exit__(self, exc_type, exc_val, exc_tb):
-        # Restore original stdout/stderr
         sys.stdout = self.original_stdout
         sys.stderr = self.original_stderr
 
@@ -124,11 +119,11 @@ class DeploymentWorker(QThread):
     frame_updated = pyqtSignal('PyQt_PyObject')  # For live view
     result_updated = pyqtSignal(dict)  # For inference results
     terminal_output = pyqtSignal(str)  # For terminal output in GUI
-    stdout_captured = pyqtSignal(str)  # For captured stdout/stderr
 
-    def __init__(self, pipeline_data: Dict[str, Any]):
+    def __init__(self, pipeline_data: Dict[str, Any], stdout_queue: queue.Queue):
         super().__init__()
         self.pipeline_data = pipeline_data
+        self.stdout_queue = stdout_queue   # thread-safe queue; drained by dialog's QTimer
         self.should_stop = False
         self.orchestrator = None
         
@@ -184,7 +179,7 @@ class DeploymentWorker(QThread):
             # Create InferencePipeline instance with stdout capture
             try:
                 # Capture all stdout/stderr during pipeline operations
-                with StdoutCapture(self.stdout_captured.emit):
+                with StdoutCapture(self.stdout_queue):
                     pipeline = converter.create_inference_pipeline(config)
                     
                     self.progress_updated.emit(80, "Initializing workflow orchestrator...")
@@ -389,6 +384,9 @@ class DeploymentWorker(QThread):
 class DeploymentDialog(QDialog):
     """Main deployment dialog with comprehensive deployment management."""
 
+    # Emitted from the wait_for_stop background thread; connected slot runs on main thread
+    _stop_done = pyqtSignal(bool)  # True = stopped cleanly
+
     def __init__(self, pipeline_data: Dict[str, Any], parent=None):
         super().__init__(parent)
         
@@ -867,8 +865,11 @@ Stage Configurations:
         self.terminal_output_display.clear()
         self.terminal_output_display.append("Pipeline deployment started - terminal output will appear here...")
         
+        # Create thread-safe queue for stdout captured from non-Qt threads
+        self._stdout_queue: queue.Queue = queue.Queue(maxsize=1000)
+
         # Create and start deployment worker
-        self.deployment_worker = DeploymentWorker(self.pipeline_data)
+        self.deployment_worker = DeploymentWorker(self.pipeline_data, self._stdout_queue)
         self.deployment_worker.progress_updated.connect(self.update_progress)
         self.deployment_worker.topology_analyzed.connect(self.update_topology_results)
         self.deployment_worker.conversion_completed.connect(self.on_conversion_completed)
@@ -878,8 +879,14 @@ Stage Configurations:
         self.deployment_worker.frame_updated.connect(self.update_live_view)
         self.deployment_worker.result_updated.connect(self.update_inference_results)
         self.deployment_worker.terminal_output.connect(self.update_terminal_output)
-        self.deployment_worker.stdout_captured.connect(self.update_terminal_output)
 
+        # Drain stdout queue from main thread every 100 ms to avoid cross-thread signal warnings
+        self._stdout_drain_timer = QTimer(self)
+        self._stdout_drain_timer.timeout.connect(self._drain_stdout_queue)
+        self._stdout_drain_timer.start(100)
+
+        # Stop timer and flush queue when worker finishes (runs on main thread via signal)
+        self.deployment_worker.finished.connect(self._on_worker_finished)
 
         self.deployment_worker.start()
     
@@ -898,14 +905,30 @@ Stage Configurations:
                 
                 self.deployment_worker.stop()
                 
-                # Wait for worker to finish in a separate thread to avoid blocking UI
+                # Wait for worker to finish in a separate thread to avoid blocking UI.
+                # All UI updates happen in _on_stop_done (main thread, via signal).
+                self._stop_done.connect(self._on_stop_done)
+
                 def wait_for_stop():
-                    if self.deployment_worker.wait(5000):  # Wait up to 5 seconds
+                    success = self.deployment_worker.wait(5000)  # Wait up to 5 seconds
+                    self._stop_done.emit(success)
+
+                import threading
+                threading.Thread(target=wait_for_stop, daemon=True).start()
+
+    def _on_stop_done(self, success: bool):
+        """Called on the main thread after the stop background thread has waited for the worker."""
+        # Disconnect so re-running won't accumulate connections
+        try:
+            self._stop_done.disconnect(self._on_stop_done)
+        except TypeError:
+            pass
+
+        if success:
             self.deployment_log.append("Inference stopped successfully.")
         else:
             self.deployment_log.append("Warning: Inference may not have stopped cleanly.")
 
-                    # Update UI on main thread
         self.stop_button.setVisible(False)
         self.deploy_button.setEnabled(True)
         self.close_button.setText("Close")
@@ -913,8 +936,22 @@ Stage Configurations:
         self.status_label.setText("Inference stopped")
         self.dongle_status.setText("Pipeline stopped")
 
-                import threading
-                threading.Thread(target=wait_for_stop, daemon=True).start()
+    def _on_worker_finished(self):
+        """Called on the main thread when the deployment worker thread exits."""
+        if hasattr(self, '_stdout_drain_timer'):
+            self._stdout_drain_timer.stop()
+        self._drain_stdout_queue()  # flush any remaining output
+
+    def _drain_stdout_queue(self):
+        """Drain the stdout queue and forward lines to the terminal display (main thread only)."""
+        if not hasattr(self, '_stdout_queue'):
+            return
+        try:
+            while True:
+                text = self._stdout_queue.get_nowait()
+                self.update_terminal_output(text)
+        except queue.Empty:
+            pass
 
     def update_progress(self, value: int, message: str):
         """Update deployment progress."""