diff --git a/libs/code/deepagents_code/server_graph.py b/libs/code/deepagents_code/server_graph.py
index b6f8ad613e..ae113dbae2 100644
--- a/libs/code/deepagents_code/server_graph.py
+++ b/libs/code/deepagents_code/server_graph.py
@@ -40,9 +40,14 @@
 
 if TYPE_CHECKING:
     from collections.abc import Awaitable, Callable, Mapping
+    from contextlib import AbstractContextManager
 
     from deepagents.backends.composite import CompositeBackend
 
+    EnvironmentContext = Callable[
+        [Mapping[str, str] | None], AbstractContextManager[None]
+    ]
+
     from deepagents_code.config import CredentialsSnapshot
     from deepagents_code.extensions.registry import ExtensionRegistry
     from deepagents_code.offload_middleware import OffloadOperation
@@ -257,12 +262,6 @@ async def _make_graphs(
             offload operation bound to that backend.
     """
     config = config_override or ServerConfig.from_env()
-    from deepagents_code.config import (
-        Credentials,
-        _preview_dotenv_environ,
-        use_environment,
-    )
-
     workspace_path = (
         project_context_override.user_cwd
         if project_context_override is not None
@@ -278,15 +277,25 @@ async def _make_graphs(
     # rejects when invoked directly from the server loop (see issue #5043),
     # for the same reason as the offload in `_make_graphs_in_environment`.
     def _resolve_workspace_environment() -> tuple[
-        Mapping[str, str], CredentialsSnapshot
+        Mapping[str, str], CredentialsSnapshot, EnvironmentContext
     ]:
+        from deepagents_code.config import (
+            Credentials,
+            _preview_dotenv_environ,
+            use_environment,
+        )
+
         environ = MappingProxyType(_preview_dotenv_environ(start_path=workspace_path))
-        return environ, Credentials.snapshot_from_environment(
-            start_path=workspace_path,
-            environ=environ,
+        return (
+            environ,
+            Credentials.snapshot_from_environment(
+                start_path=workspace_path,
+                environ=environ,
+            ),
+            use_environment,
         )
 
-    workspace_env, workspace_credentials = await asyncio.to_thread(
+    workspace_env, workspace_credentials, use_environment = await asyncio.to_thread(
         _resolve_workspace_environment
     )
 
diff --git a/libs/code/tests/unit_tests/test_server_graph.py b/libs/code/tests/unit_tests/test_server_graph.py
index 46ee1e6b54..5932d79e83 100644
--- a/libs/code/tests/unit_tests/test_server_graph.py
+++ b/libs/code/tests/unit_tests/test_server_graph.py
@@ -4,9 +4,10 @@
 
 import importlib
 import os
+import subprocess
 import sys
 from types import ModuleType, SimpleNamespace
-from typing import Any
+from typing import TYPE_CHECKING, Any
 from unittest.mock import AsyncMock, MagicMock, Mock, patch
 
 import pytest
@@ -14,6 +15,9 @@
 from deepagents_code._env_vars import SERVER_ENV_PREFIX
 from deepagents_code._server_config import ServerConfig
 
+if TYPE_CHECKING:
+    from pathlib import Path
+
 
 @pytest.fixture(autouse=True)
 def _disable_extensions(monkeypatch: pytest.MonkeyPatch) -> None:
@@ -84,6 +88,47 @@ async def build() -> object:
         assert calls == 1
         assert results == [graph_obj, graph_obj, graph_obj]
 
+    def test_config_bootstrap_runs_off_the_blockbuster_loop(
+        self, tmp_path: Path
+    ) -> None:
+        """Profile validation must not block the server event loop."""
+        profile = tmp_path / "profile"
+        profile.mkdir()
+        env = os.environ.copy()
+        env["DEEPAGENTS_HOME"] = str(profile)
+        env.pop("DEEPAGENTS_HOME_IS_DEFAULT", None)
+        code = """
+import asyncio
+from unittest.mock import AsyncMock, patch
+from blockbuster import blockbuster_ctx
+from deepagents_code._server_config import ServerConfig
+import deepagents_code.server_graph as module
+
+async def main():
+    runtime = module.ServerRuntime(object(), object(), object())
+    with patch.object(
+        module,
+        "_make_graphs_in_environment",
+        new=AsyncMock(return_value=runtime),
+    ):
+        with blockbuster_ctx():
+            assert await module._make_graphs(
+                config_override=ServerConfig(no_mcp=True)
+            ) is runtime
+
+asyncio.run(main())
+"""
+
+        process = subprocess.run(
+            [sys.executable, "-c", code],
+            env=env,
+            check=False,
+            capture_output=True,
+            text=True,
+        )
+
+        assert process.returncode == 0, process.stderr
+
     def test_criteria_context_tools_use_identity_allowlist_in_tool_order(self) -> None:
         """Criteria tools should be known context objects in main-tool order."""
         module = _import_fresh_server_graph()