chore: import upstream snapshot with attribution

interfaces/frame.py

@@ -0,0 +1,20 @@
+from pydantic import BaseModel, Field
+from typing import List, Optional, Union, Dict, Tuple, Literal
+
+
+class Frame(BaseModel):
+    shot_idx: int = Field(
+        description="The index of the shot in the sequence, starting from 0."
+    )
+
+    frame_type: Literal["first", "last"] = Field(
+        description="The type of the frame, 'first' for the first frame of the shot, 'last' for the last frame of the shot."
+    )
+
+    cam_idx: int = Field(
+        description="The index of the camera used for this frame, starting from 0."
+    )
+
+    vis_char_idxs: List[int] = Field(
+        description="A list of indices of characters that are visible in this frame, corresponding to the character list provided in the input."
+    )