Harden RC7 API response contracts

backend/app/schemas/common.py

@@ -1,15 +1,23 @@
 from __future__ import annotations
 
+from typing import Any, Generic, Literal, TypeVar
+
 from pydantic import BaseModel, Field
 
 
-class Envelope(BaseModel):
-    data: object
+DataT = TypeVar("DataT")
 
 
-class PaginatedEnvelope(BaseModel):
-    items: list
+class Envelope(BaseModel, Generic[DataT]):
+    data: DataT
+
+
+class ItemList(BaseModel, Generic[DataT]):
+    items: list[DataT]
     total: int
+
+
+class PaginatedEnvelope(ItemList[DataT], Generic[DataT]):
     limit: int
     offset: int
 
@@ -28,4 +36,19 @@ class ApiErrorItem(BaseModel):
 
 
 class ApiErrorEnvelope(BaseModel):
-    error: ApiErrorItem
+    error: str
+    message: str
+    details: dict | list = Field(default_factory=dict)
+    request_id: str | None = None
+
+
+class GeoJsonFeature(BaseModel):
+    type: Literal["Feature"]
+    id: str | int | None = None
+    geometry: dict[str, Any] | None
+    properties: dict[str, Any] = Field(default_factory=dict)
+
+
+class GeoJsonFeatureCollection(BaseModel):
+    type: Literal["FeatureCollection"]
+    features: list[GeoJsonFeature]