Outline knowledge base MCP Server

//! Error handling //! //! Centralized error types for the application. /// Application result type pub type Result<T> = std::result::Result<T, Error>; /// Application error types #[derive(Debug, thiserror::Error)] pub enum Error { /// Configuration errors #[error("Configuration error: {message}")] Config { /// Error description message: String, /// Optional source error #[source] source: Option<Box<dyn std::error::Error + Send + Sync>>, }, /// Network and HTTP errors #[error("Network error: {context}")] Network { /// Operation context context: String, /// Source error #[source] source: reqwest::Error, }, /// API response errors #[error("API error: {status} - {message}")] Api { /// HTTP status code status: u16, /// Error message message: String, /// Response body (if available) body: Option<String>, }, /// Protocol errors (MCP, JSON-RPC) #[error("Protocol error: {protocol} - {message}")] Protocol { /// Protocol type protocol: String, /// Error message message: String, /// JSON-RPC error code (if applicable) code: Option<i32>, }, /// Tool execution errors #[error("Tool error '{tool_name}': {message}")] Tool { /// Tool name tool_name: String, /// Error message message: String, /// Source error #[source] source: Option<Box<dyn std::error::Error + Send + Sync>>, }, /// Transport layer errors (STDIO, HTTP) #[error("Transport error: {transport_type}")] Transport { /// Transport type (STDIO, HTTP, etc.) transport_type: String, /// Source error #[source] source: Box<dyn std::error::Error + Send + Sync>, }, /// JSON parsing and validation errors #[error("JSON error: {context}")] Json { /// Operation context context: String, /// Source error #[source] source: serde_json::Error, }, /// Input validation errors #[allow(dead_code)] #[error("Validation error: {field} - {message}")] Validation { /// Field with error field: String, /// Validation error description message: String, }, /// Serialization/deserialization errors #[allow(dead_code)] #[error("Serialization error: {context}")] Serialization { /// Operation context context: String, /// Source error #[source] source: serde_json::Error, }, /// I/O operation errors #[error("I/O error: {operation}")] Io { /// Operation description operation: String, /// Source error #[source] source: std::io::Error, }, /// Internal application errors #[allow(dead_code)] #[error("Internal error: {message}")] Internal { /// Error description message: String, /// Optional context context: Option<String>, }, } impl Error { /// Create configuration error #[allow(dead_code)] pub fn config(message: impl Into<String>) -> Self { Self::Config { message: message.into(), source: None, } } /// Create configuration error with source pub fn config_with_source( message: impl Into<String>, source: impl std::error::Error + Send + Sync + 'static, ) -> Self { Self::Config { message: message.into(), source: Some(Box::new(source)), } } /// Create transport error #[allow(dead_code)] pub fn transport( transport_type: impl Into<String>, source: impl std::error::Error + Send + Sync + 'static, ) -> Self { Self::Transport { transport_type: transport_type.into(), source: Box::new(source), } } /// Create network error #[allow(dead_code)] pub fn network(context: impl Into<String>, source: reqwest::Error) -> Self { Self::Network { context: context.into(), source, } } /// Create API error #[allow(dead_code)] pub fn api(status: u16, message: impl Into<String>) -> Self { Self::Api { status, message: message.into(), body: None, } } /// Create API error with response body #[allow(dead_code)] pub fn api_with_body(status: u16, message: impl Into<String>, body: impl Into<String>) -> Self { Self::Api { status, message: message.into(), body: Some(body.into()), } } /// Create JSON error #[allow(dead_code)] pub fn json(context: impl Into<String>, source: serde_json::Error) -> Self { Self::Json { context: context.into(), source, } } /// Create I/O error #[allow(dead_code)] pub fn io(operation: impl Into<String>, source: std::io::Error) -> Self { Self::Io { operation: operation.into(), source, } } } // Automatic conversions for common error types impl From<reqwest::Error> for Error { fn from(err: reqwest::Error) -> Self { Self::Network { context: "HTTP request failed".to_string(), source: err, } } } impl From<serde_json::Error> for Error { fn from(err: serde_json::Error) -> Self { Self::Json { context: "JSON operation failed".to_string(), source: err, } } } impl From<std::io::Error> for Error { fn from(err: std::io::Error) -> Self { Self::Io { operation: "I/O operation failed".to_string(), source: err, } } } impl From<url::ParseError> for Error { fn from(err: url::ParseError) -> Self { Self::Config { message: format!("Invalid URL format: {err}"), source: Some(Box::new(err)), } } } impl From<std::string::FromUtf8Error> for Error { fn from(err: std::string::FromUtf8Error) -> Self { Self::Transport { transport_type: "String conversion".to_string(), source: Box::new(err), } } }