Add mypy configuration and fix critical type issues

- Install types-PyYAML for proper YAML type checking
- Fix Optional types in server.py to handle None cases properly
- Add mypy configuration in pyproject.toml with strict settings
- Add dev dependencies with mypy and type stubs
- Fix CLI Path type conversion for recordings_dir

Remaining minor type annotations can be addressed in future PRs.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: haasonsaas

pyproject.toml

@@ -38,7 +38,32 @@ test = [
     "pytest>=7.0",
     "pytest-asyncio>=0.21",
 ]
+dev = [
+    "mypy>=1.0",
+    "types-PyYAML",
+    "pytest>=7.0",
+    "pytest-asyncio>=0.21",
+]
 
 [tool.pytest.ini_options]
 addopts = "-q"
 asyncio_mode = "auto"
+
+[tool.mypy]
+python_version = "3.9"
+warn_return_any = true
+warn_unused_configs = true
+disallow_untyped_defs = true
+disallow_incomplete_defs = true
+check_untyped_defs = true
+disallow_untyped_decorators = true
+no_implicit_optional = true
+warn_redundant_casts = true
+warn_unused_ignores = true
+warn_no_return = true
+warn_unreachable = true
+strict_equality = true
+
+[[tool.mypy.overrides]]
+module = "tests.*"
+disallow_untyped_defs = false

src/mocktopus/cli.py

@@ -2,7 +2,8 @@
 
 import sys
 import logging
-from typing import List, Dict, Any
+from pathlib import Path
+from typing import List, Dict, Any, Optional
 import click
 
 from .core import Scenario, load_yaml
@@ -58,7 +59,7 @@ def serve_cmd(scenario: str, port: int, host: str, mode: str, recordings_dir: st
     server = MockServer(
         scenario=scenario_obj,
         mode=server_mode,
-        recordings_dir=recordings_dir,
+        recordings_dir=Path(recordings_dir) if recordings_dir else None,
         real_openai_key=openai_key,
         real_anthropic_key=anthropic_key,
         host=host,

src/mocktopus/server.py

@@ -116,10 +116,12 @@ async def _handle_mock_openai(self, request: Request, model: str, messages: List
         rule.consume()
 
         # Check if this is an error response
-        if "error_type" in respond_config:
+        if respond_config and "error_type" in respond_config:
             return await self._handle_error_response(respond_config)
 
-        # Extract response config
+        # Extract response config (handle None case)
+        if not respond_config:
+            respond_config = {}
         content = respond_config.get("content", "Mocked response")
         delay_ms = respond_config.get("delay_ms", 0)
         tool_calls = respond_config.get("tool_calls", [])
@@ -241,7 +243,7 @@ async def _handle_error_response(self, error_config: Dict[str, Any]) -> Response
             )
 
     async def _stream_openai_response(self, request: Request, content: str, model: str,
-                                      tool_calls: List[Dict] = None) -> StreamResponse:
+                                      tool_calls: Optional[List[Dict]] = None) -> StreamResponse:
         """Stream OpenAI response using Server-Sent Events"""
 
         response = web.StreamResponse()