diff --git a/.gitignore b/.gitignore
index ae69a1f..24c743c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -22,3 +22,4 @@ evaluations/results/
 # Installed locally from an exact source lock. Upstream redistribution permission is unresolved.
 skills/alibabacloud-resourcecenter-search/
 venv/
+.venv/
diff --git a/src/titmas_action_gate/contracts.py b/src/titmas_action_gate/contracts.py
index c93ea3e..4c9e26c 100644
--- a/src/titmas_action_gate/contracts.py
+++ b/src/titmas_action_gate/contracts.py
@@ -47,6 +47,17 @@ def schema_directory() -> Path:
     )
 
 
+@functools.cache
+def _schema_registry() -> Registry:
+    directory = schema_directory()
+    resources = []
+    for path in directory.glob("*.schema.json"):
+        candidate = json.loads(path.read_text(encoding="utf-8"))
+        if isinstance(candidate.get("$id"), str):
+            resources.append((candidate["$id"], Resource.from_contents(candidate)))
+    return Registry().with_resources(resources)
+
+
 @functools.cache
 def _validator(contract: str) -> Draft202012Validator:
     try:
@@ -55,12 +66,7 @@ def _validator(contract: str) -> Draft202012Validator:
         raise ContractValidationError("SCHEMA_UNKNOWN", f"Unknown contract: {contract}") from exc
     directory = schema_directory()
     schema = json.loads((directory / filename).read_text(encoding="utf-8"))
-    resources = []
-    for path in directory.glob("*.schema.json"):
-        candidate = json.loads(path.read_text(encoding="utf-8"))
-        if isinstance(candidate.get("$id"), str):
-            resources.append((candidate["$id"], Resource.from_contents(candidate)))
-    registry = Registry().with_resources(resources)
+    registry = _schema_registry()
     return Draft202012Validator(schema, registry=registry, format_checker=FormatChecker())
 
 
diff --git a/src/titmas_action_gate/service.py b/src/titmas_action_gate/service.py
index 90d7164..df6bc08 100644
--- a/src/titmas_action_gate/service.py
+++ b/src/titmas_action_gate/service.py
@@ -5,6 +5,7 @@
 import hashlib
 import hmac
 import json
+from dataclasses import dataclass
 from datetime import datetime, timedelta
 from pathlib import Path
 from typing import Any
@@ -20,7 +21,6 @@
 from .provider import GitHubProvider
 from .signing import HmacRecordSigner
 from .store import AppendOnlyStore
-from dataclasses import dataclass
 
 
 @dataclass(frozen=True)
diff --git a/tests/test_security_argument_injection.py b/tests/test_security_argument_injection.py
index 3990256..4d8bb42 100644
--- a/tests/test_security_argument_injection.py
+++ b/tests/test_security_argument_injection.py
@@ -1,9 +1,8 @@
 import unittest
-import subprocess
-from unittest.mock import patch, MagicMock
+from unittest.mock import MagicMock, patch
 
 from titmas_action_gate.provider import GhCliProvider
-from titmas_action_gate.errors import ActionGateError
+
 
 class ProviderSecurityTests(unittest.TestCase):
     @patch("subprocess.run")
diff --git a/tests/test_workflow.py b/tests/test_workflow.py
index 61c356d..461a3bf 100644
--- a/tests/test_workflow.py
+++ b/tests/test_workflow.py
@@ -1,8 +1,8 @@
+import json
 import tempfile
 import unittest
 from pathlib import Path
 
-import json
 from titmas_action_gate.workflow import validate_agentteams_template, write_demo_report
 
 
@@ -83,7 +83,7 @@ def test_write_demo_report(self):
         self.assertEqual(result_path, output_file)
         self.assertTrue(output_file.exists())
 
-        with open(output_file, "r", encoding="utf-8") as f:
+        with open(output_file, encoding="utf-8") as f:
             content = json.load(f)
 
         self.assertEqual(content, report_data)
@@ -95,7 +95,7 @@ def test_write_demo_report_creates_directories(self):
         write_demo_report(report_data, output_file)
 
         self.assertTrue(output_file.exists())
-        with open(output_file, "r", encoding="utf-8") as f:
+        with open(output_file, encoding="utf-8") as f:
             content = json.load(f)
 
         self.assertEqual(content, report_data)