iii Motia mcp server

This pull request adds a comprehensive error handling and introspection system for the Motia MCP Server, along with utilities and middleware for validating requests and origins. The changes introduce structured error classes, core and origin validation middleware, new MCP service modules for tools and resources, and helper functions for building JSON-RPC responses. These improvements enhance the reliability, security, and introspectability of the Motia API.

Testing state in MCP Inspector

Error Handling and Middleware

Introduced a base error class BaseError for consistent API error handling, including status codes, error codes, and metadata, with a toJSON method for API responses.
Added specific MCP error classes (e.g., MCPOriginError, MCPMethodNotFoundError, etc.) for granular error reporting in MCP operations.
Implemented coreMiddleware to catch and log errors, handle validation and custom errors, and return standardized error responses.
Added originValidationMiddleware to enforce MCP specification by validating the Origin header and preventing DNS rebinding attacks.

Motia Introspection and MCP Services

Created motia-introspection.ts, a singleton service for introspecting Motia internals (steps, flows, topics, endpoints) for use by MCP tools and resources.
Added MCP service exports (tools, resources, prompts, motia-introspection) to centralize domain-driven MCP logic.

MCP Tools and Resources

Defined a set of MCP tools (e.g., trigger_workflow, call_api, get_execution_logs, etc.) with input schemas for workflow automation and state management.
Implemented resource listing and reading functions, allowing MCP clients to discover and retrieve Motia steps, flows, topics, endpoints, and documentation (including a Markdown quick start guide).

JSON-RPC Response Utilities