Recover metadata from the response when missing from older data

src/paperoni/prompt.py

@@ -9,7 +9,8 @@
 from google import genai
 from google.genai import types
 from paperazzi.platforms.utils import Message
-from paperazzi.utils import _make_key as paperazzi_make_key, disk_cache, disk_store
+from paperazzi.utils import _make_key as paperazzi_make_key
+from paperazzi.utils import disk_cache, disk_store
 from serieux.features.comment import CommentProxy, comment_field
 from serieux.features.encrypt import Secret
 
@@ -62,6 +63,36 @@ def cleanup_schema(schema: dict | Type[Any]) -> dict:
     return schema
 
 
+def _derive_metadata(
+    response: types.GenerateContentResponse,
+    structured_model: Type[Any] | None,
+) -> "PromptMetadata":
+    """Derive token counts and parsed output from response, return PromptMetadata."""
+    usage = response.usage_metadata
+    if usage is not None:
+        input_tokens = usage.prompt_token_count
+        output_tokens = (
+            usage.candidates_token_count + usage.thoughts_token_count
+        )
+        total_tokens = usage.total_token_count
+    else:
+        input_tokens = output_tokens = total_tokens = None
+
+    if structured_model is not None:
+        metadata_type = PromptMetadata[structured_model]
+        parsed = serieux.deserialize(structured_model, response.parsed)
+    else:
+        metadata_type = PromptMetadata
+        parsed = None
+
+    return metadata_type(
+        input_tokens=input_tokens,
+        output_tokens=output_tokens,
+        total_tokens=total_tokens,
+        parsed=parsed,
+    )
+
+
 @dataclass
 class PromptMetadata[T]:
     # The number of input tokens in the prompt
@@ -109,15 +140,17 @@ def load(self, file_obj: BinaryIO) -> types.GenerateContentResponse:
             metadata_type = PromptMetadata
 
         data = dict(data)
-        comment = data.pop(comment_field, {})
+        metadata = data.pop(comment_field, {})
+        response: types.GenerateContentResponse = (
+            types.GenerateContentResponse.model_validate(data)
+        )
+        metadata = metadata or _derive_metadata(response, self.content_type)
+
         with SERIEUX_LOCK:
-            response: types.GenerateContentResponse = (
-                types.GenerateContentResponse.model_validate(data)
-            )
+            metadata = serieux.deserialize(metadata_type, metadata)
 
-            comment = serieux.deserialize(metadata_type, comment)
-            response = CommentProxy(response, comment)
-            response.parsed = comment.parsed
+        response = CommentProxy(response, metadata)
+        response.parsed = metadata.parsed
 
         return response
 
@@ -224,30 +257,9 @@ def prompt(
             contents=contents, model=model, config=config
         )
 
-        # Extract token information from usage_metadata
-        input_tokens = response.usage_metadata.prompt_token_count
-        output_tokens = (
-            response.usage_metadata.candidates_token_count
-            + response.usage_metadata.thoughts_token_count
-        )
-        total_tokens = response.usage_metadata.total_token_count
+        metadata = _derive_metadata(response, structured_model)
 
-        if structured_model is not None:
-            metadata_type = PromptMetadata[structured_model]
-            parsed = serieux.deserialize(structured_model, response.parsed)
-        else:
-            metadata_type = PromptMetadata
-            parsed = None
-
-        response = CommentProxy(
-            response,
-            metadata_type(
-                input_tokens=input_tokens,
-                output_tokens=output_tokens,
-                total_tokens=total_tokens,
-                parsed=parsed,
-            ),
-        )
+        response = CommentProxy(response, metadata)
 
         return response