diff --git a/core/services/scanner_service.py b/core/services/scanner_service.py
index 5faad4a..2270208 100644
--- a/core/services/scanner_service.py
+++ b/core/services/scanner_service.py
@@ -7,16 +7,16 @@ class ScannerService:
     """Coordinate local model listing and path-template discovery."""
 
     def __init__(self, context: RouteContext):
-        self.asyncio = context.get("asyncio")
-        self.get_model_files = context.get("get_model_files")
-        self.infer_download_path_templates = context.get(
+        self.asyncio = context.require("asyncio")
+        self.get_model_files = context.require("get_model_files")
+        self.infer_download_path_templates = context.require(
             "infer_download_path_templates"
         )
-        self.invalidate_local_hash_match_cache = context.get(
+        self.invalidate_local_hash_match_cache = context.require(
             "invalidate_local_hash_match_cache"
         )
-        self.to_bool = context.get("to_bool")
-        self.web = context.get("web")
+        self.to_bool = context.require("to_bool")
+        self.web = context.require("web")
 
     async def get_models(self, request):
         """Return the locally available models, optionally forcing a rescan."""
diff --git a/tests/test_directory_routes.py b/tests/test_directory_routes.py
index 66962b2..9836c54 100644
--- a/tests/test_directory_routes.py
+++ b/tests/test_directory_routes.py
@@ -11,6 +11,7 @@ from aiohttp import web
 
 from core.routes.context import RouteContext
 from core.routes.directories import register_directory_routes
+from core.type_utils import to_bool
 
 
 class _Routes:
@@ -58,6 +59,7 @@ def _build_routes(**overrides):
         ),
         "get_model_files": MagicMock(return_value=[]),
         "infer_download_path_templates": MagicMock(return_value=[]),
+        "invalidate_local_hash_match_cache": MagicMock(),
         "is_civarchive_available": MagicMock(return_value=False),
         "is_lora_manager_archive_available": MagicMock(return_value=False),
         "json_api_endpoint": _json_api_endpoint,
@@ -70,6 +72,7 @@ def _build_routes(**overrides):
         "split_path_segments": lambda value: [
             part for part in str(value).replace("\\", "/").split("/") if part
         ],
+        "to_bool": to_bool,
         "web": web,
     }
     values.update(overrides)
diff --git a/tests/test_route_context_contract.py b/tests/test_route_context_contract.py
new file mode 100644
index 0000000..4e0249c
--- /dev/null
+++ b/tests/test_route_context_contract.py
@@ -0,0 +1,19 @@
+import pytest
+
+from core.routes.context import RouteContext
+from core.services.scanner_service import ScannerService
+
+
+def test_route_context_remains_immutable_after_construction():
+    values = {"dependency": "original"}
+    context = RouteContext(values)
+    values["dependency"] = "changed"
+
+    assert context.get("dependency") == "original"
+    with pytest.raises(KeyError, match="Missing route dependency: absent"):
+        context.require("absent")
+
+
+def test_scanner_service_requires_mandatory_route_dependencies():
+    with pytest.raises(KeyError, match="Missing route dependency: asyncio"):
+        ScannerService(RouteContext({}))
diff --git a/tests/test_scanner_routes.py b/tests/test_scanner_routes.py
index da7136e..fe3afa0 100644
--- a/tests/test_scanner_routes.py
+++ b/tests/test_scanner_routes.py
@@ -46,6 +46,7 @@ def _build_metadata_routes():
         "get_model_files": MagicMock(
             return_value=[{"filename": "model.safetensors"}]
         ),
+        "infer_download_path_templates": MagicMock(return_value=[]),
         "get_progress_response": MagicMock(),
         "invalidate_local_hash_match_cache": MagicMock(),
         "json_api_endpoint": _json_api_endpoint,
@@ -86,6 +87,7 @@ def _build_directory_routes():
         "infer_download_path_templates": MagicMock(
             return_value=[{"category": "checkpoints"}]
         ),
+        "invalidate_local_hash_match_cache": MagicMock(),
         "is_civarchive_available": MagicMock(return_value=False),
         "is_lora_manager_archive_available": MagicMock(return_value=False),
         "json_api_endpoint": _json_api_endpoint,
@@ -98,6 +100,7 @@ def _build_directory_routes():
         "routes": routes,
         "self": SimpleNamespace(logger=MagicMock()),
         "split_path_segments": MagicMock(return_value=[]),
+        "to_bool": to_bool,
         "web": web,
     }
     register_directory_routes(RouteContext(values))