Implement tool filtering module

This commit implements a flexible tool filtering system for Claude Desktop compatibility.

Features:
- Whitelist mode: Only enable specified tools
- Blacklist mode: Disable specified tools (default enables all)
- Passthrough mode: No filtering (default if no lists provided)
- Validation: Prevents conflicting enabled/disabled lists

Implementation:
- ToolFilter class with three filtering modes
- should_include_tool() for individual tool checks
- filter_tools_list() for filtering tool definition lists
- filter_tools_response() for filtering MCP list_tools responses
- get_filter_stats() for observability and debugging

This module integrates with the configuration loader (#11) and will be used by the HTTP MCP server (#14) to ensure only compatible tools are exposed to Claude Desktop.

Closes #12

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/gitea_http_wrapper/filtering/__init__.py

@@ -1,3 +1,5 @@
 """Tool filtering module for Claude Desktop compatibility."""
 
-__all__ = []
+from .filter import ToolFilter
+
+__all__ = ["ToolFilter"]

src/gitea_http_wrapper/filtering/filter.py

@@ -0,0 +1,108 @@
+"""Tool filtering for Claude Desktop compatibility."""
+
+from typing import Any
+
+
+class ToolFilter:
+    """
+    Filter MCP tools based on enabled/disabled lists.
+
+    This class handles tool filtering to ensure only compatible tools are exposed
+    to Claude Desktop, preventing crashes from unsupported tool schemas.
+    """
+
+    def __init__(
+        self,
+        enabled_tools: list[str] | None = None,
+        disabled_tools: list[str] | None = None,
+    ):
+        """
+        Initialize tool filter.
+
+        Args:
+            enabled_tools: List of tool names to enable. If None, all tools are enabled.
+            disabled_tools: List of tool names to disable. Takes precedence over enabled_tools.
+
+        Raises:
+            ValueError: If both enabled_tools and disabled_tools are specified.
+        """
+        if enabled_tools is not None and disabled_tools is not None:
+            raise ValueError(
+                "Cannot specify both enabled_tools and disabled_tools. Choose one filtering mode."
+            )
+
+        self.enabled_tools = set(enabled_tools) if enabled_tools else None
+        self.disabled_tools = set(disabled_tools) if disabled_tools else None
+
+    def should_include_tool(self, tool_name: str) -> bool:
+        """
+        Determine if a tool should be included based on filter rules.
+
+        Args:
+            tool_name: Name of the tool to check.
+
+        Returns:
+            True if tool should be included, False otherwise.
+        """
+        # If disabled list is specified, exclude disabled tools
+        if self.disabled_tools is not None:
+            return tool_name not in self.disabled_tools
+
+        # If enabled list is specified, only include enabled tools
+        if self.enabled_tools is not None:
+            return tool_name in self.enabled_tools
+
+        # If no filters specified, include all tools
+        return True
+
+    def filter_tools_list(self, tools: list[dict[str, Any]]) -> list[dict[str, Any]]:
+        """
+        Filter a list of tool definitions.
+
+        Args:
+            tools: List of tool definitions (dicts with at least a 'name' field).
+
+        Returns:
+            Filtered list of tool definitions.
+        """
+        return [tool for tool in tools if self.should_include_tool(tool.get("name", ""))]
+
+    def filter_tools_response(self, response: dict[str, Any]) -> dict[str, Any]:
+        """
+        Filter tools from an MCP list_tools response.
+
+        Args:
+            response: MCP response dict containing 'tools' list.
+
+        Returns:
+            Filtered response with tools list updated.
+        """
+        if "tools" in response and isinstance(response["tools"], list):
+            response = response.copy()
+            response["tools"] = self.filter_tools_list(response["tools"])
+        return response
+
+    def get_filter_stats(self) -> dict[str, Any]:
+        """
+        Get statistics about the filter configuration.
+
+        Returns:
+            Dict containing filter mode and tool counts.
+        """
+        if self.disabled_tools is not None:
+            return {
+                "mode": "blacklist",
+                "disabled_count": len(self.disabled_tools),
+                "disabled_tools": sorted(self.disabled_tools),
+            }
+        elif self.enabled_tools is not None:
+            return {
+                "mode": "whitelist",
+                "enabled_count": len(self.enabled_tools),
+                "enabled_tools": sorted(self.enabled_tools),
+            }
+        else:
+            return {
+                "mode": "passthrough",
+                "message": "All tools enabled",
+            }