* feat: implement MCP elicitation support for interactive user input
Adds comprehensive elicitation functionality according to MCP 2025-06-18 specification:
Core Features:
- ElicitationAction enum (Accept, Decline, Cancel)
- CreateElicitationRequestParam and CreateElicitationResult structures
- Protocol version V_2025_06_18 with elicitation methods
- Full JSON-RPC integration with method constants
Capabilities Integration:
- ElicitationCapability with schema validation support
- ClientCapabilities builder pattern integration
- enable_elicitation() and enable_elicitation_schema_validation() methods
Handler Support:
- create_elicitation method in ClientHandler and ServerHandler traits
- Integration with existing request/response union types
- Async/await compatible implementation
Service Layer:
- Basic create_elicitation method via macro expansion
- Four convenience methods for common scenarios:
* elicit_confirmation() - yes/no questions
* elicit_text_input() - string input with optional requirements
* elicit_choice() - selection from multiple options
* elicit_structured_input() - complex data via JSON Schema
Comprehensive Testing:
- 11 test cases covering all functionality aspects
- JSON serialization/deserialization validation
- MCP specification compliance verification
- Error handling and edge cases
- Performance benchmarks
- Capabilities integration tests
All tests pass and code follows project standards.
* feat: add typed elicitation API with enhanced error handling
- Add new 'elicitation' feature that depends on 'client' and 'schemars'
- Implement elicit<T>() method for type-safe elicitation with automatic schema generation
- Remove convenience methods (elicit_confirmation, elicit_text_input, elicit_choice)
- Add ElicitationError enum with detailed error variants:
- Service: underlying service errors
- UserDeclined: user cancelled or declined request
- ParseError: response parsing failed with context
- NoContent: no response content provided
- Update documentation with comprehensive examples and error handling
- Add comprehensive tests for typed elicitation and error handling
* fix: correct elicitation direction to comply with MCP 2025-06-18
- Remove CreateElicitationRequest from ClientRequest - clients cannot initiate elicitation
- Move elicit methods from client to server - servers now request user input
- Add comprehensive direction tests verifying Server→Client→Server flow
- Maintain CreateElicitationResult in ClientResult for proper responses
- Update handlers to reflect correct message routing
- Add elicitation feature flag for typed schema generation
Fixes elicitation direction to match specification where servers request
interactive user input from clients, not the reverse.
* feat: add elicitation capability checking for server methods
- Add supports_elicitation() method to check client capabilities
- Add CapabilityNotSupported error variant to ElicitationError
- Update elicit_structured_input() to check capabilities before execution
- Update elicit<T>() method to check capabilities before execution
- Add comprehensive tests for capability checking functionality
- Tests verify that servers check client capabilities before sending elicitation requests
- Ensures compliance with MCP 2025-06-18 specification requirement
* fix: json rpc message schema
* fix: doc tests
* fix: cargo nightly fmt checks
* fix: clippy
* refactor: separate elicitation methods into dedicated impl block for RoleServer
- Move (supports_elicitation, elicit_structured_input, elicit) to separate impl block
- Move ElicitationError definition to elicitation methods section
- Keep base methods (create_message, list_roots, notify_*) in main impl block with macro
- Add section comments to distinguish general and elicitation-specific methods
* revert: rollback LATEST protocol version to V_2025_03_26
* fix: remove protocol version assertions
- Remove assertions for V_2025_06_18 protocol version
* fix: fmt checks
* feat: add timeout support for elicitation methods
- Add peer_req_with_timeout macro variants for timeout-enabled methods
- Implement create_elicitation_with_timeout() method
- Implement elicit_with_timeout() for typed elicitation with timeout
- Refactor elicit() to use elicit_with_timeout() internally
- Add 8 comprehensive timeout tests covering validation, error handling, and realistic scenarios
- Fix elicitation feature dependencies in Cargo.toml
- Add proper feature gates for elicitation-specific code
* feat: add timeout validation to prevent DoS attacks
- Add InvalidTimeout error variant for comprehensive validation
- Implement validate_timeout function with security limits (1ms-300s)
- Integrate validation into peer_req_with_timeout macros
- Add comprehensive security tests for timeout validation
- Prevent DoS attacks through unreasonable timeout values
* feat: separate UserDeclined and UserCancelled elicitation errors
According to MCP specification and PR feedback, decline and cancel
actions should be handled differently:
- UserDeclined: explicit user rejection (clicked "Decline", "No", etc.)
- UserCancelled: dismissal without explicit choice (closed dialog, Escape, etc.)
Changes:
- Split ElicitationError::UserDeclined into two distinct error types
- Update error handling logic to map each ElicitationAction correctly
- Improve documentation with proper action semantics
- Add comprehensive tests for new error types and action mapping
- Update examples to demonstrate proper error handling
This provides better error granularity allowing servers to handle
explicit declines vs cancellations appropriately as per MCP spec.
* feat: add compile-time type safety for elicitation methods
Add ElicitationSafe trait and elicit_safe\! macro to ensure elicit<T>()
methods are only used with types that generate appropriate JSON object
schemas, addressing type safety concerns from PR feedback.
Features:
- ElicitationSafe marker trait for compile-time constraints
- elicit_safe\! macro for opt-in type safety declaration
- Updated elicit<T> and elicit_with_timeout<T> to require ElicitationSafe bound
- Comprehensive documentation with examples and rationale
- Full test coverage for new type safety features
This prevents common mistakes like:
- elicit::<String>() - primitives not suitable for object schemas
- elicit::<Vec<i32>>() - arrays don't match client expectations
Breaking change: Existing code must add elicit_safe\!(TypeName) declarations
for types used with elicit methods. This is an intentional safety improvement.
* Revert "feat: add timeout validation to prevent DoS attacks"
This reverts commit 829624212b4fb55ec32566329af7ec195c987ef5.
* fix: correct doctest example in elicit_safe macro documentation
- Remove invalid async/await usage in doctest example
- Comment out the actual usage line to show intent without compilation errors
- Maintain clear documentation of the macro's purpose and usage
* refactor: remove redundant elicitation direction tests
- Remove test_elicitation_not_in_client_request (duplicated functionality)
- Remove redundant ServerRequest match in test_elicitation_direction_server_to_client
- Direction compliance is already verified by the remaining comprehensive test
- Reduces test fragility and maintenance burden
* feat: add elicitation example with user name collection
- Add elicitation server example demonstrating real MCP usage
- Implement greet_user tool with context.peer.elicit::<T>() API
- Show type-safe elicitation with elicit_safe! macro
- Include reset_name tool and MCP Inspector instructions
- Update examples documentation and dependencies
* fix: add Default impl to ElicitationServer for clippy
Resolves clippy::new_without_default warning by implementing
Default trait for ElicitationServer struct.
81ff3159f9