Prevent signal handler in GUI mode and improve thread cleanup

2 files changed, 11 insertions, 10 deletions

diff --git a/picostream/cli.py b/picostream/cli.py
index fa72518..c902348 100644
--- a/picostream/cli.py
+++ b/picostream/cli.py
@@ -46,11 +46,13 @@ class Streamer:
         downsample_mode: str = "average",
         offset_v: float = 0.0,
         max_buffer_seconds: Optional[float] = None,
+        is_gui_mode: bool = False,
     ) -> None:
         # --- Configuration ---
         self.output_file = output_file
         self.debug = debug
         self.enable_live_plot = enable_live_plot
+        self.is_gui_mode = is_gui_mode
         self.plot_window_s = plot_window_s
         self.max_buffer_seconds = max_buffer_seconds
 
@@ -212,8 +214,9 @@ class Streamer:
 
         # --- Signal Handling ---
         # Only set the signal handler if not in GUI mode.
-        # In GUI mode, the main function will handle signals to quit the Qt app.
-        if not self.enable_live_plot:
+        # In GUI mode, the main window handles shutdown signals.
+        # In CLI plot mode, the main() function handles SIGINT to quit the Qt app.
+        if not self.is_gui_mode and not self.enable_live_plot:
             signal.signal(signal.SIGINT, self.signal_handler)
 
         # --- Live Plotting (optional) ---
diff --git a/picostream/main.py b/picostream/main.py
index b2f03b4..b40c2c1 100644
--- a/picostream/main.py
+++ b/picostream/main.py
@@ -45,8 +45,8 @@ class StreamerWorker(QObject):
             self.streamer.run()
         except Exception as e:
             self.error.emit(str(e))
-            return  # Do not emit finished signal on error
-        self.finished.emit()
+        finally:
+            self.finished.emit()
 
     def stop(self) -> None:
         """Signal the acquisition to stop."""
@@ -174,6 +174,7 @@ class PicoStreamMainWindow(QMainWindow):
             if self.live_only_checkbox.isChecked()
             else None,
             "enable_live_plot": False,
+            "is_gui_mode": True,
         }
 
         self.thread = QThread()
@@ -196,7 +197,7 @@ class PicoStreamMainWindow(QMainWindow):
         self.stop_button.setEnabled(False)
 
     def on_acquisition_finished(self) -> None:
-        """Handle successful acquisition completion."""
+        """Handle acquisition completion (both success and failure)."""
         print("Acquisition finished.")
         self.start_button.setEnabled(True)
         self.stop_button.setEnabled(False)
@@ -206,11 +207,8 @@ class PicoStreamMainWindow(QMainWindow):
     def on_acquisition_error(self, err_msg: str) -> None:
         """Handle acquisition error."""
         print(f"Acquisition error: {err_msg}")
-        # In a real app, show a QMessageBox
-        self.start_button.setEnabled(True)
-        self.stop_button.setEnabled(False)
-        self.thread = None
-        self.worker = None
+        # In a real app, this would show a QMessageBox.
+        # The UI state is reset in on_acquisition_finished.
 
     def closeEvent(self, event: QCloseEvent) -> None:
         """Handle window close event."""