diff --git a/Fuser/auto_agent.py b/Fuser/auto_agent.py
index dadaa8f..563e174 100644
--- a/Fuser/auto_agent.py
+++ b/Fuser/auto_agent.py
@@ -61,7 +61,7 @@
     get_platform_choices,
     get_platform,
 )
-from utils.providers.models import get_model_provider
+from utils.providers.models import get_model_provider, is_model_available
 
 
 # ------------------------
@@ -138,6 +138,20 @@ def _dotted_name(n: ast.AST) -> str:
     return ".".join(parts)
 
 
+def _validate_cfg_models(cfg) -> None:
+    """Given a router config, remove all unavailable model choices."""
+    if (ka_model := cfg.get("ka_model")) and not is_model_available(ka_model):
+        del cfg["ka_model"]
+
+    if models := cfg.get("llm_models"):
+        remove = [k for k, v in models.items() if not is_model_available(v)]
+        for k in remove:
+            del models[k]
+
+        if not models:
+            del cfg["llm_models"]
+
+
 @dataclass
 class Complexity:
     has_control_flow: bool
@@ -475,6 +489,7 @@ def solve(self, problem_path: Path) -> RouteResult:
             )
             route_conf = cached.get("confidence")
             route_cfg = cached.get("config") or {}
+            _validate_cfg_models(route_cfg)
 
         if strategy is None:
             # Try LLM-driven decision
@@ -487,6 +502,8 @@ def solve(self, problem_path: Path) -> RouteResult:
                     "route_strategy": strategy,
                     "confidence": route_conf,
                 }
+                route_cfg = cache[code_hash].get("config") or {}
+                _validate_cfg_models(route_cfg)
                 _save_router_cache(cache)
             except Exception:
                 # No provider or failure; fall back later
diff --git a/tests/fuser/test_auto_agent_cache.py b/tests/fuser/test_auto_agent_cache.py
new file mode 100644
index 0000000..0b99079
--- /dev/null
+++ b/tests/fuser/test_auto_agent_cache.py
@@ -0,0 +1,52 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from unittest.mock import patch
+
+from Fuser.auto_agent import _validate_cfg_models
+
+
+class TestValidateCfgModels:
+    def test_validate_cfg_models_removes_unavailable(self):
+        """Test that unavailable models are removed from config."""
+        cfg = {
+            "ka_model": "gpt-5",
+            "llm_models": {
+                "extract": "gpt-5",
+                "dispatch": "o4-mini",
+            },
+        }
+
+        with patch("Fuser.auto_agent.is_model_available", return_value=False):
+            _validate_cfg_models(cfg)
+
+        assert "ka_model" not in cfg
+        assert "llm_models" not in cfg
+
+    def test_validate_cfg_models_keeps_available(self):
+        """Test that available models are kept in config."""
+        cfg = {
+            "ka_model": "gpt-5",
+            "llm_models": {
+                "extract": "gpt-5",
+                "dispatch": "o4-mini",
+            },
+        }
+
+        with patch("Fuser.auto_agent.is_model_available", return_value=True):
+            _validate_cfg_models(cfg)
+
+        assert cfg["ka_model"] == "gpt-5"
+        assert cfg["llm_models"]["extract"] == "gpt-5"
+        assert cfg["llm_models"]["dispatch"] == "o4-mini"