🛠️ Implement Advanced Tool System with Search, Details, Compare, Ensemble, and Recipe Tools

[Copilot]

This PR implements the comprehensive Advanced Tool System requested in the requirements, providing enhanced query capabilities through specialized tool handlers that route queries to appropriate processors based on intent analysis.

Implementation Overview

Core Infrastructure

• IToolHandler - Base interface for all tool implementations
• IToolExecutor - Service to manage tool execution pipeline
• BaseToolHandler - Abstract class providing common functionality
• Integration with NLWebService - Seamless routing between tool execution and standard processing

Tool Handlers Implemented

1. SearchToolHandler - Enhanced keyword and semantic search

• Query optimization (removes redundant search terms like "search for")
• Enhanced relevance scoring based on query term matching
• Result sorting and filtering improvements
• Example: "search for REST API documentation" → optimized search with better ranking

2. DetailsToolHandler - Comprehensive information retrieval

• Subject extraction from natural language queries using regex patterns
• Focused detail gathering with enhanced filtering
• Supports patterns like "tell me about X", "what is Y", "describe Z"
• Example: "tell me about GraphQL" → detailed information about GraphQL

3. CompareToolHandler - Side-by-side comparison analysis

• Automatic extraction of comparison subjects from queries
• Structured comparison result formatting
• Handles patterns like "X vs Y", "compare A and B", "difference between X and Y"
• Example: "compare React vs Vue" → structured comparison results

4. EnsembleToolHandler - Cohesive recommendation sets

• Multi-category recommendation engine
• Coherent item grouping and thematic organization
• Supports planning and recommendation queries
• Example: "recommend Italian dinner menu" → appetizer, main, dessert suggestions

5. RecipeToolHandler - Specialized culinary assistance

• Ingredient substitution guidance
• Food pairing and accompaniment suggestions
• Cooking technique and recipe support
• Example: "substitute butter in baking" → alternative ingredient options

Integration Features

Backward Compatibility

• Zero Breaking Changes - When ToolSelectionEnabled = false, uses standard processing pipeline
• Graceful Fallback - Tool execution failures automatically fall back to standard processing
• Existing API Preserved - All existing endpoints and behavior maintained

Configuration

{
  "NLWebNet": {
    "ToolSelectionEnabled": true
  }
}

Dependency Injection

Automatic registration via AddAdvancedToolSystem() extension method:

services.AddNLWebNet(); // Includes tool system automatically

Query Processing Flow

1. Intent Analysis - IToolSelector analyzes query for tool selection
2. Tool Routing - IToolExecutor routes to appropriate handler
3. Specialized Processing - Each tool applies domain-specific enhancements
4. Result Enhancement - Tools format and optimize results for their domain
5. Fallback Safety - Automatic fallback to standard processing on errors

Sample Supported Queries

• Search: "find information about microservices"
• Details: "what is Docker?", "describe OAuth 2.0"
• Compare: "Node.js versus Python for backend"
• Ensemble: "suggest tools for DevOps pipeline"
• Recipe: "what goes with grilled salmon?"

Testing

• 81 tests passing including new ToolExecutorTests
• Integration tests verify tool selection and execution
• Backward compatibility validated through existing test suite
• Error handling tested for graceful fallback scenarios

Documentation

Added comprehensive usage guide at doc/advanced-tool-system-guide.md with:

• Configuration examples
• Query patterns for each tool
• Custom tool development guidelines
• Integration instructions

This implementation provides significant feature differentiation while maintaining full backward compatibility and robust error handling.

Fixes #37.

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Pull Request Overview

This PR integrates a new Advanced Tool System that enhances query handling by routing requests to specialized tool handlers when enabled, while preserving backward compatibility and fallback behavior.

• Introduces five new tool handlers (search, details, compare, ensemble, recipe) inheriting from BaseToolHandler
• Extends NLWebService to select and execute tools before falling back to the standard pipeline
• Adds DI registration via AddAdvancedToolSystem() and comprehensive unit tests for the executor

Reviewed Changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tests/NLWebNet.Tests/Services/ToolExecutorTests.cs	Added tests for available tools, execution success, and error
src/NLWebNet/Services/SearchToolHandler.cs	Implements enhanced search logic and result optimization
src/NLWebNet/Services/DetailsToolHandler.cs	Implements subject extraction and detailed information logic
src/NLWebNet/Services/CompareToolHandler.cs	Implements side-by-side comparison processing
src/NLWebNet/Services/EnsembleToolHandler.cs	Implements cohesive recommendation set creation
src/NLWebNet/Services/RecipeToolHandler.cs	Implements recipe-specific query handling and result formatting
src/NLWebNet/Services/BaseToolHandler.cs	Provides shared tooling for error/success response creation
src/NLWebNet/Services/IToolHandler.cs	Defines the tool handler interface
src/NLWebNet/Services/IToolExecutor.cs	Defines and implements tool execution routing
src/NLWebNet/Services/NLWebService.cs	Adds tool selection/execution logic to request processing
src/NLWebNet/Extensions/ToolSystemServiceCollectionExtensions.cs	Registers the tool system services in DI container
src/NLWebNet/Extensions/ServiceCollectionExtensions.cs	Integrates advanced tool system into core AddNLWebNet methods
doc/advanced-tool-system-guide.md	Documentation for configuration, usage patterns, and examples
.github/custom-instructions.md	Updated internal guidelines (not directly affecting functionality)

Comments suppressed due to low confidence (1)

src/NLWebNet/Services/RecipeToolHandler.cs:113

• [nitpick] Hardcoded site identifier "Recipe" may lead to inconsistent casing compared to the ToolType property ("recipe"); consider using ToolType or a consistent value for uniform site naming across handlers.

            "Recipe",