some fixes

python_app/gui/controllers/app_window_preprocess_mixin.py

@@ -2,6 +2,8 @@
 
 from __future__ import annotations
 
+from PyQt6.QtCore import QTimer
+
 from python_app.gui.preprocess_dialog import PreprocessDialog
 from python_app.gui.trace_png_export import export_trace_png
 from python_app.orchestration.preprocess_assets import (
@@ -519,13 +521,23 @@ class AppWindowPreprocessMixin:
         if session is None:
             self._show_error("No active capture sequence")
             return
+        # The capture blocks the event loop, so clicks made during it are delivered
+        # only after it finishes. `_begin_preprocess_capture` disables the action
+        # buttons for that whole window (re-enabled via a posted event), so a queued
+        # click lands on a disabled button instead of silently starting — and
+        # advancing the combo cursor of — another capture.
+        if not self._begin_preprocess_capture():
+            return
 
         try:
-            capture_result = session.capture_current_combo()
-        except Exception as exc:  # noqa: BLE001
-            self._on_capture_combo_failed(session, exc)
-            return
-        self._record_preprocess_capture(session, capture_result)
+            try:
+                capture_result = session.capture_current_combo()
+            except Exception as exc:  # noqa: BLE001
+                self._on_capture_combo_failed(session, exc)
+                return
+            self._record_preprocess_capture(session, capture_result)
+        finally:
+            self._end_preprocess_capture()
 
     def _capture_all_remaining(self) -> None:
         """Capture all remaining combos for the active preprocess session."""
@@ -539,6 +551,8 @@ class AppWindowPreprocessMixin:
                 details=self._capture_state_details(),
             )
             return
+        if not self._begin_preprocess_capture():
+            return
 
         display_name = preprocess_asset_display_name(session.kind)
         dialog = self._ensure_preprocess_dialog()
@@ -547,13 +561,40 @@ class AppWindowPreprocessMixin:
             f"{display_name} batch capture started: remaining="
             f"{session.state().total_count - session.state().captured_count}"
         )
-        while not session.is_complete():
-            try:
-                capture_result = session.capture_current_combo()
-            except Exception as exc:  # noqa: BLE001
-                self._on_capture_combo_failed(session, exc)
-                return
-            self._record_preprocess_capture(session, capture_result)
+        try:
+            while not session.is_complete():
+                try:
+                    capture_result = session.capture_current_combo()
+                except Exception as exc:  # noqa: BLE001
+                    self._on_capture_combo_failed(session, exc)
+                    return
+                self._record_preprocess_capture(session, capture_result)
+        finally:
+            self._end_preprocess_capture()
+
+    def _begin_preprocess_capture(self) -> bool:
+        """Mark a blocking combo capture as running; refuse when one already is.
+
+        Returns False for a duplicate request (e.g. a click delivered while an
+        error dialog inside a capture pumps the event loop).
+        """
+        if self._preprocess_capture_busy:
+            self._log("Preprocess combo capture already in progress; ignoring duplicate request.")
+            return False
+        self._preprocess_capture_busy = True
+        # Disable the sequence action buttons for the whole blocked window.
+        self._update_capture_dialog_state()
+        return True
+
+    def _end_preprocess_capture(self) -> None:
+        """Re-enable capture actions after the pending input backlog is discarded.
+
+        The zero-delay timer fires only after Qt has dispatched the window-system
+        events queued while the capture blocked the loop; those clicks hit the
+        still-disabled buttons and are dropped, then the buttons come back.
+        """
+        self._preprocess_capture_busy = False
+        QTimer.singleShot(0, self._update_capture_dialog_state)
 
     def _on_capture_combo_failed(
         self,
@@ -817,6 +858,10 @@ class AppWindowPreprocessMixin:
                 and state.current_combo is not None
             ),
             variant_count=state.variant_count,
+            # While a blocking capture is executing, every action stays disabled no
+            # matter what the session state allows: clicks queued during the freeze
+            # must land on disabled buttons (see `_end_preprocess_capture`).
+            actions_enabled=not self._preprocess_capture_busy,
         )
 
     def _cleanup_capture_session(self) -> None: