diff --git a/src/openjarvis/server/agent_manager_routes.py b/src/openjarvis/server/agent_manager_routes.py
index cd6061a3..21936445 100644
--- a/src/openjarvis/server/agent_manager_routes.py
+++ b/src/openjarvis/server/agent_manager_routes.py
@@ -111,24 +111,35 @@ def _make_lightweight_system(
     model: str,
     config: Any = None,
 ) -> _LightweightSystem:
-    """Build a minimal system with a plain OllamaEngine.
+    """Build a minimal system with a fresh inference engine.
 
     The server's ``app.state.engine`` is heavily wrapped
     (MultiEngine -> InstrumentedEngine -> GuardrailsEngine) and can
-    return empty content from background threads.  Create a fresh
-    OllamaEngine directly (no health checks or model discovery that
-    could interfere with in-flight Ollama requests).
+    return empty content from background threads. Create a fresh
+    engine directly (no health checks or model discovery that
+    could interfere with in-flight requests).
     """
     try:
-        from openjarvis.engine.ollama import OllamaEngine
+        from openjarvis.engine._discovery import get_engine
 
         cfg = config
         if cfg is None:
             from openjarvis.core.config import load_config
 
             cfg = load_config()
-        host = cfg.engine.ollama.host if cfg else ""
-        plain_engine = OllamaEngine(host=host) if host else OllamaEngine()
+
+        pref = cfg.intelligence.preferred_engine
+        key = pref or cfg.engine.default
+        resolved = get_engine(cfg, key)
+
+        if resolved is not None:
+            plain_engine = resolved[1]
+        else:
+            from openjarvis.engine.ollama import OllamaEngine
+
+            host = cfg.engine.ollama.host if cfg else ""
+            plain_engine = OllamaEngine(host=host) if host else OllamaEngine()
+
         # Wrap with InstrumentedEngine so agent ticks are recorded
         # in telemetry (FLOPs, energy, cost savings).
         try:
@@ -842,9 +853,7 @@ async def _stream_managed_agent(
 
         app_config = load_config()
 
-    final_system_prompt = _build_managed_system_prompt(
-        system_prompt or "", app_config
-    )
+    final_system_prompt = _build_managed_system_prompt(system_prompt or "", app_config)
 
     if final_system_prompt and final_system_prompt.strip():
         llm_messages.append(
diff --git a/tests/server/test_agent_manager_routes.py b/tests/server/test_agent_manager_routes.py
index 738144db..4902563c 100644
--- a/tests/server/test_agent_manager_routes.py
+++ b/tests/server/test_agent_manager_routes.py
@@ -5,6 +5,7 @@ from __future__ import annotations
 import json
 import tempfile
 from pathlib import Path
+from types import SimpleNamespace
 from unittest.mock import MagicMock
 
 import pytest
@@ -488,3 +489,51 @@ class TestResolveToolSpecs:
 
         assert _resolve_tool_specs(None) == []
         assert _resolve_tool_specs([]) == []
+
+
+class TestLightweightSystemEngineResolution:
+    """Regression for #477 / #514: the managed-agent lightweight system must
+    resolve the user's *configured* engine (preferred_engine, else
+    engine.default), not a hardcoded OllamaEngine. We assert the key passed to
+    ``get_engine`` — captured before the system is built — rather than the final
+    (telemetry-wrapped) engine object.
+    """
+
+    @staticmethod
+    def _cfg(preferred, default):
+        # context_from_memory absent on .agent -> memory backend resolves to None
+        return SimpleNamespace(
+            intelligence=SimpleNamespace(preferred_engine=preferred),
+            engine=SimpleNamespace(default=default, ollama=SimpleNamespace(host="")),
+            agent=SimpleNamespace(),
+        )
+
+    def _capture_get_engine(self, monkeypatch):
+        captured = {}
+
+        def fake_get_engine(cfg, key):
+            captured["key"] = key
+            return ("resolved", MagicMock())
+
+        monkeypatch.setattr("openjarvis.engine._discovery.get_engine", fake_get_engine)
+        return captured
+
+    def test_resolves_preferred_engine_over_default(self, monkeypatch):
+        pytest.importorskip("fastapi")
+        from openjarvis.server import agent_manager_routes as amr
+
+        captured = self._capture_get_engine(monkeypatch)
+        amr._make_lightweight_system(
+            engine=MagicMock(), model="m", config=self._cfg("vllm", "ollama")
+        )
+        assert captured["key"] == "vllm"
+
+    def test_falls_back_to_engine_default_without_preference(self, monkeypatch):
+        pytest.importorskip("fastapi")
+        from openjarvis.server import agent_manager_routes as amr
+
+        captured = self._capture_get_engine(monkeypatch)
+        amr._make_lightweight_system(
+            engine=MagicMock(), model="m", config=self._cfg(None, "llamacpp")
+        )
+        assert captured["key"] == "llamacpp"