fix(api): wrap pre-paginated list responses

app/api/v1/rest_router.py

@@ -201,18 +201,39 @@ def _with_header_project_context(endpoint, route_name: str):
 
 def _with_pagination(endpoint):
     signature = inspect.signature(endpoint)
-    if "limit" in signature.parameters or "offset" in signature.parameters:
-        return endpoint
+    handler_limit_parameter = "limit" if "limit" in signature.parameters else None
+    handler_offset_parameter = next(
+        (
+            parameter_name
+            for parameter_name in ("offset", "skip")
+            if parameter_name in signature.parameters
+        ),
+        None,
+    )
+    handler_handles_pagination = bool(
+        handler_limit_parameter or handler_offset_parameter
+    )
 
     @wraps(endpoint)
     async def wrapper(*args, **kwargs):
-        limit = kwargs.pop("_rest_limit")
-        offset = kwargs.pop("_rest_offset")
+        if handler_handles_pagination:
+            limit = kwargs.get(handler_limit_parameter, 0)
+            offset = kwargs.get(handler_offset_parameter, 0)
+        else:
+            limit = kwargs.pop("_rest_limit")
+            offset = kwargs.pop("_rest_offset")
         result = endpoint(*args, **kwargs)
         if inspect.isawaitable(result):
             result = await result
         if not isinstance(result, list):
             return result
+        if handler_handles_pagination:
+            return Page(
+                items=result,
+                total=offset + len(result),
+                limit=limit or len(result),
+                offset=offset,
+            )
         return Page(
             items=result[offset : offset + limit],
             total=len(result),
@@ -221,22 +242,23 @@ def _with_pagination(endpoint):
         )
 
     parameters = list(signature.parameters.values())
-    parameters.extend(
-        [
-            inspect.Parameter(
-                "_rest_limit",
-                kind=inspect.Parameter.KEYWORD_ONLY,
-                annotation=int,
-                default=Query(100, ge=1, le=1000, alias="limit"),
-            ),
-            inspect.Parameter(
-                "_rest_offset",
-                kind=inspect.Parameter.KEYWORD_ONLY,
-                annotation=int,
-                default=Query(0, ge=0, alias="offset"),
-            ),
-        ]
-    )
+    if not handler_handles_pagination:
+        parameters.extend(
+            [
+                inspect.Parameter(
+                    "_rest_limit",
+                    kind=inspect.Parameter.KEYWORD_ONLY,
+                    annotation=int,
+                    default=Query(100, ge=1, le=1000, alias="limit"),
+                ),
+                inspect.Parameter(
+                    "_rest_offset",
+                    kind=inspect.Parameter.KEYWORD_ONLY,
+                    annotation=int,
+                    default=Query(0, ge=0, alias="offset"),
+                ),
+            ]
+        )
     wrapper.__signature__ = signature.replace(parameters=parameters)
     return wrapper
 

tests/api/test_openapi_contract.py

@@ -4,7 +4,7 @@ from pathlib import Path
 from uuid import uuid4
 
 import pytest
-from fastapi import FastAPI
+from fastapi import APIRouter, FastAPI, Query
 from fastapi.routing import APIRoute
 from fastapi.testclient import TestClient
 
@@ -254,3 +254,31 @@ def test_rest_runtime_consumes_injected_project_context(monkeypatch) -> None:
     assert response.json()["items"] == [
         {"scheme_name": "burst_case", "scheme_type": "burst_analysis"}
     ]
+
+
+def test_rest_runtime_wraps_handler_paginated_list() -> None:
+    source_router = APIRouter()
+
+    @source_router.get("/records", response_model=list[int])
+    async def list_records(
+        skip: int = Query(0, ge=0),
+        limit: int = Query(2, ge=1, le=10),
+    ) -> list[int]:
+        records = [10, 20, 30, 40]
+        return records[skip : skip + limit]
+
+    app = FastAPI(redirect_slashes=False)
+    app.include_router(build_rest_router(source_router.routes), prefix="/api/v1")
+
+    response = TestClient(app, raise_server_exceptions=False).get(
+        "/api/v1/records",
+        params={"skip": 1, "limit": 2},
+    )
+
+    assert response.status_code == 200
+    assert response.json() == {
+        "items": [20, 30],
+        "total": 3,
+        "limit": 2,
+        "offset": 1,
+    }