Make review mode navigation fully non-blocking

Replace blocking stop_review_analysis() on navigation press with
non-blocking search.stop() signal. The join+restart is deferred to the
debounce handler which fires 300ms after the last button press, by which
time the old thread has already exited.

Also skip stale analysis messages from the old position during debounce
to prevent incorrect UI updates.

Agent-Logs-Url: https://github.com/fsmosca/Python-Easy-Chess-GUI/sessions/0e57255b-5a2d-4189-9dc6-ce5b07d5f43f

Co-authored-by: fsmosca <22366935+fsmosca@users.noreply.github.com>

Author: Copilot

python_easy_chess_gui.py

@@ -2931,41 +2931,46 @@ def refresh_review_analysis(self, window):
             return
         self.start_review_analysis(window)
 
-    def poll_review_analysis(self, window):
-        """Consume engine messages for Review mode analysis."""
-        updated = False
-        while True:
-            try:
-                msg = self.review_queue.get_nowait()
-            except queue.Empty:
-                break
-            except Exception:
-                logging.exception('Failed to read Review mode analysis queue.')
-                break
-
-            msg_str = str(msg)
-            if 'multipv_info' in msg_str:
-                try:
-                    line_no, info_line = msg_str.split(' | ', 1)
-                    line_number = int(line_no.strip())
-                    if not 1 <= line_number <= REVIEW_ANALYSIS_MULTIPV_LINES:
-                        raise ValueError('Invalid MultiPV line number')
-                    line_index = line_number - 1
-                    info_line = info_line.rsplit(' multipv_info', 1)[0]
-                    self.review_analysis_lines[line_index] = \
-                        self.shorten_review_analysis_line(info_line)
-                    updated = True
-                except Exception:
-                    logging.exception('Failed to parse Review mode analysis info.')
-            elif 'bestmove' in msg_str:
-                if self.review_analysis_search is not None:
-                    self.review_analysis_search.join()
-                    self.review_analysis_engine = \
-                        self.review_analysis_search.get_engine()
-                    self.review_analysis_search = None
-                if self.review_analysis_enabled:
-                    self.review_analysis_status = \
-                        'Analysis ready - {}'.format(self.analysis_id_name)
+    def poll_review_analysis(self, window):
+        """Consume engine messages for Review mode analysis."""
+        updated = False
+        is_debouncing = bool(self.review_nav_last_time)
+        while True:
+            try:
+                msg = self.review_queue.get_nowait()
+            except queue.Empty:
+                break
+            except Exception:
+                logging.exception('Failed to read Review mode analysis queue.')
+                break
+
+            msg_str = str(msg)
+            if 'multipv_info' in msg_str:
+                # Skip stale analysis info from the old position while
+                # waiting for the debounce to restart analysis.
+                if is_debouncing:
+                    continue
+                try:
+                    line_no, info_line = msg_str.split(' | ', 1)
+                    line_number = int(line_no.strip())
+                    if not 1 <= line_number <= REVIEW_ANALYSIS_MULTIPV_LINES:
+                        raise ValueError('Invalid MultiPV line number')
+                    line_index = line_number - 1
+                    info_line = info_line.rsplit(' multipv_info', 1)[0]
+                    self.review_analysis_lines[line_index] = \
+                        self.shorten_review_analysis_line(info_line)
+                    updated = True
+                except Exception:
+                    logging.exception('Failed to parse Review mode analysis info.')
+            elif 'bestmove' in msg_str:
+                if self.review_analysis_search is not None:
+                    self.review_analysis_search.join()
+                    self.review_analysis_engine = \
+                        self.review_analysis_search.get_engine()
+                    self.review_analysis_search = None
+                if self.review_analysis_enabled and not is_debouncing:
+                    self.review_analysis_status = \
+                        'Analysis ready - {}'.format(self.analysis_id_name)
                     updated = True
 
         if updated:
@@ -3113,10 +3118,10 @@ def start_review_mode(self, window):
             # poll_review_analysis() called earlier in the loop.
             if button == sg.TIMEOUT_KEY:
                 # Restart analysis after debounce delay following navigation.
-                if (self.review_nav_last_time
+                nav_time = self.review_nav_last_time
+                if (nav_time
                         and self.review_analysis_enabled
-                        and self.review_analysis_search is None
-                        and time.time() - self.review_nav_last_time
+                        and time.time() - nav_time
                             >= REVIEW_NAV_DEBOUNCE_SEC):
                     self.review_nav_last_time = 0
                     self.start_review_analysis(review_window)
@@ -3213,7 +3218,11 @@ def start_review_mode(self, window):
             if position_changed:
                 self.update_review_window(review_window)
                 if self.review_analysis_enabled:
-                    self.stop_review_analysis()
+                    # Signal the analysis thread to stop without blocking.
+                    # The actual join and restart happen in the debounce
+                    # handler after the user stops pressing buttons.
+                    if self.review_analysis_search is not None:
+                        self.review_analysis_search.stop()
                     self.review_nav_last_time = time.time()
                     self.review_analysis_lines = [''] * REVIEW_ANALYSIS_MULTIPV_LINES
                     self.review_analysis_status = 'Waiting...'