Resolve postponed annotations before validation and schema creation

tests/test_argument_regressions.py

@@ -1,6 +1,8 @@
+import sys
+from types import ModuleType
+
 import pytest
 from fastapi.testclient import TestClient
-
 from great_ai import GreatAI
 
 
@@ -32,3 +34,25 @@ def test_positional_only_inputs_keep_their_bindings(isolated_context: None) -> N
         response = client.post("/predict", json={"first": "b", "second": 3})
         assert response.status_code == 200
         assert response.json()["output"] == "bbb"
+
+
+def test_postponed_model_annotations_resolve_in_their_module(
+    isolated_context: None, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    module = ModuleType("great_ai_test_annotations")
+    monkeypatch.setitem(sys.modules, module.__name__, module)
+    exec(
+        "from __future__ import annotations\n"
+        "from pydantic import BaseModel\n"
+        "class Payload(BaseModel):\n    value: int\n"
+        "def predict(data: Payload) -> int:\n    return data.value\n",
+        module.__dict__,
+    )
+    service = GreatAI.create(module.predict)
+    with pytest.raises(TypeError):
+        service("wrong")
+    with TestClient(service.app) as client:
+        response = client.post("/predict", json={"data": {"value": 7}})
+        assert response.status_code == 200
+        assert response.json()["output"] == 7
+        assert client.get("/openapi.json").status_code == 200