fix: address rpc and mcp review followups

tests/wf_sources_mcp/test_auth_storage_exports.py

@@ -47,6 +47,19 @@ def test_wf_sources_mcp_auth_adapters_interpret_mcp_payload() -> None:
     assert mcp_auth_env(auth) == {"GITHUB_TOKEN": "secret"}
 
 
+def test_wf_sources_mcp_auth_headers_preserve_existing_authorization_case() -> None:
+    auth = AuthRecord(
+        connection_id="github.work",
+        scheme="bearer",
+        payload={
+            "token": "secret",
+            "headers": {"authorization": "Bearer custom"},
+        },
+    )
+
+    assert mcp_auth_headers(auth) == {"authorization": "Bearer custom"}
+
+
 def test_wf_sources_mcp_file_stores_keep_existing_disk_shape(tmp_path) -> None:
     auth_store = FileAuthStore(tmp_path / "auth-root")
     catalog_store = FileCatalogStore(tmp_path / "catalog-root")

tests/wf_sources_mcp/test_runtime.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import asyncio
 from contextlib import AsyncExitStack
 from typing import Any
 
@@ -259,6 +260,41 @@ async def test_runtime_pool_reuses_unchanged_connection() -> None:
     assert created == [connection]
 
 
+@pytest.mark.asyncio
+async def test_runtime_pool_serializes_concurrent_session_creation() -> None:
+    created: list[McpSourceConnection] = []
+    release = asyncio.Event()
+
+    async def create_session(
+        connection: McpSourceConnection, auth: AuthRecord | None
+    ) -> PersistentMcpSession:
+        created.append(connection)
+        await release.wait()
+
+        async def _call(tool_name: str, payload: dict[str, Any]) -> ToolCallResult:
+            return ToolCallResult(outcome="ok", output={"echoed": payload["text"]})
+
+        return PersistentMcpSession(
+            connection=connection,
+            auth=auth,
+            call_callback=_call,
+        )
+
+    pool = McpRuntimePool(session_factory=create_session)
+    connection = _connection()
+
+    first = asyncio.create_task(pool.get_session(connection, None))
+    second = asyncio.create_task(pool.get_session(connection, None))
+    await asyncio.sleep(0)
+    release.set()
+
+    first_session, second_session = await asyncio.gather(first, second)
+    await pool.close_all()
+
+    assert first_session is second_session
+    assert created == [connection]
+
+
 def test_runtime_fingerprint_changes_when_transport_changes() -> None:
     original = _connection()
     changed = McpSourceConnection(

tests/wf_sources_mcp/test_schema_models.py

@@ -111,6 +111,45 @@ def test_model_from_schema_allows_extra_fields_and_tolerates_unknown_shapes() ->
     assert dumped["extra"] == "kept"
 
 
+def test_model_from_schema_preserves_complex_array_item_annotations() -> None:
+    model = model_from_schema(
+        "NestedArrayInput",
+        {
+            "type": "object",
+            "properties": {
+                "items": {
+                    "type": "array",
+                    "items": {
+                        "type": ["object", "null"],
+                    },
+                },
+            },
+        },
+    )
+
+    annotation = model.model_fields["items"].annotation
+
+    assert str(annotation) == "list[dict[str, typing.Any] | None]"
+
+
+def test_model_from_schema_preserves_optional_complex_annotations() -> None:
+    model = model_from_schema(
+        "OptionalObjectInput",
+        {
+            "type": "object",
+            "properties": {
+                "metadata": {
+                    "type": ["object", "null"],
+                },
+            },
+        },
+    )
+
+    annotation = model.model_fields["metadata"].annotation
+
+    assert str(annotation) == "dict[str, typing.Any] | None"
+
+
 def test_model_from_schema_exports_from_package_root() -> None:
     from wf_sources_mcp import model_from_schema as root_model_from_schema
     from wf_sources_mcp.schema_models import model_from_schema