Fix search stability and improve Escape key behavior

- Add bounds check in _mark_message_as_read to prevent IndexError
- Clear metadata_by_id when search returns no results
- Escape now focuses search input when in search mode instead of exiting
- Add focus_input() method to SearchPanel

src/mail/app.py

@@ -273,6 +273,12 @@ class EmailViewerApp(App):
 
     async def _mark_message_as_read(self, message_id: int, index: int) -> None:
         """Mark a message as read and update the UI."""
+        # Skip if message_id is invalid or index is out of bounds
+        if message_id <= 0:
+            return
+        if index < 0 or index >= len(self.message_store.envelopes):
+            return
+
         # Check if already read
         envelope_data = self.message_store.envelopes[index]
         if envelope_data and envelope_data.get("type") != "header":
@@ -885,32 +891,18 @@ class EmailViewerApp(App):
             self._update_list_view_subtitle()
 
     def action_clear_selection(self) -> None:
-        """Clear all selected messages and exit search mode."""
+        """Clear all selected messages or focus search input if in search mode."""
+        # If in search mode, focus the search input instead of exiting
+        if self.search_mode:
+            search_panel = self.query_one("#search_panel", SearchPanel)
+            search_panel.focus_input()
+            return
+
         if self.selected_messages:
             self.selected_messages.clear()
             self.refresh_list_view_items()  # Refresh all items to uncheck checkboxes
             self._update_list_view_subtitle()
 
-        # Exit search mode if active
-        if self.search_mode:
-            search_panel = self.query_one("#search_panel", SearchPanel)
-            search_panel.hide()
-            self.search_mode = False
-            self.search_query = ""
-
-            # Restore cached envelopes
-            if self._cached_envelopes:
-                self.message_store.envelopes = self._cached_envelopes
-                self._cached_envelopes = []
-                self._populate_list_view()
-
-            # Restore envelope list title
-            sort_indicator = "↑" if self.sort_order_ascending else "↓"
-            self.query_one(
-                "#envelopes_list"
-            ).border_title = f"1️⃣ Emails {sort_indicator}"
-            self._update_list_view_subtitle()
-
     def action_oldest(self) -> None:
         self.fetch_envelopes() if self.reload_needed else None
         self.show_message(self.message_store.get_oldest_id())
@@ -1017,6 +1009,7 @@ class EmailViewerApp(App):
             content_container = self.query_one(ContentContainer)
             content_container.clear_content()
             self.message_store.envelopes = []
+            self.message_store.metadata_by_id = {}
             self.total_messages = 0
             self.current_message_id = 0
             return