Require label lists only on success.

copienator/commands/gemini_for_labels.py

@@ -12,7 +12,7 @@ from pathlib import Path
 
 from google import genai
 from google.genai import types
-from pydantic import BaseModel, Field, model_validator
+from pydantic import BaseModel, ConfigDict, Field, model_validator
 
 from copienator import configuration as config
 from copienator.gemini_config import fresh_seed, thinking_config
@@ -166,7 +166,23 @@ class BoxItem(BaseModel):
     box_2d: list[int] = Field(description="Bounding box coordinates (e.g., [ymin, xmin, ymax, xmax])")
     label: str = Field(description="The label associated with the specific box")
 
+def _require_success_fields(schema: dict) -> None:
+    """Mirror the conditional payload validators in the schema sent to Gemini."""
+    required = ["list"]
+    if "name" in schema["properties"]:
+        required.append("name")
+    schema["anyOf"] = [
+        {"required": required},
+        {"required": ["error"],
+         "properties": {"error": {"type": "string", "enum": ["insufficient_crop"]}}},
+        {"required": ["upside_down_pages"],
+         "properties": {"upside_down_pages": {"type": "array", "minItems": 1}}},
+    ]
+
+
 class LabelData(BaseModel):
+    model_config = ConfigDict(json_schema_extra=_require_success_fields)
+
     upside_down_pages: typing.List[typing.Annotated[int, Field(strict=True, ge=1)]] = Field(
         default_factory=list,
         description='1-based column numbers in this image that appear upside down (180 degrees)',