(api) use most recently generated image for cover photo

invokeai/app/services/boards.py

@@ -136,11 +136,12 @@ class BoardService(BoardServiceABC):
         board_records = self._services.board_records.get_many(offset, limit)
         board_dtos = []
         for r in board_records.items:
-            cover_image_url = (
-                self._services.urls.get_image_url(r.cover_image_name, True)
-                if r.cover_image_name
-                else None
-            )
+            cover_image = self._services.image_records.get_most_recent_image_for_board(r.board_id)
+            if (cover_image):
+                cover_image_url = self._services.urls.get_image_url(cover_image.image_name, True)
+            else:
+                cover_image_url = None
+
             image_count = self._services.board_image_records.get_image_count_for_board(
                 r.board_id
             )

invokeai/app/services/image_record_storage.py

@@ -109,6 +109,11 @@ class ImageRecordStorageBase(ABC):
         """Saves an image record."""
         pass
 
+    @abstractmethod
+    def get_most_recent_image_for_board(self, board_id: str) -> ImageRecord | None:
+        """Gets the most recent image for a board."""
+        pass
+
 
 class SqliteImageRecordStorage(ImageRecordStorageBase):
     _filename: str
@@ -414,3 +419,26 @@ class SqliteImageRecordStorage(ImageRecordStorageBase):
             raise ImageRecordSaveException from e
         finally:
             self._lock.release()
+
+    def get_most_recent_image_for_board(self, board_id: str) -> Union[ImageRecord, None]:
+        try:
+            self._lock.acquire()
+            self._cursor.execute(
+                """--sql
+                SELECT images.*
+                FROM images
+                JOIN board_images ON images.image_name = board_images.image_name
+                WHERE board_images.board_id = ?
+                ORDER BY images.created_at DESC
+                LIMIT 1;
+                """,
+                (board_id,),
+            )
+
+            result = cast(Union[sqlite3.Row, None], self._cursor.fetchone())
+        finally:
+            self._lock.release()
+        if result is None:
+            return None
+        
+        return deserialize_image_record(dict(result))