agent_client_protocol_schema/v2/
error.rs

1//! Error handling for the Agent Client Protocol.
2//!
3//! This module provides error types and codes following the JSON-RPC 2.0 specification,
4//! with additional protocol-specific error codes for authentication and other ACP-specific scenarios.
5//!
6//! All methods in the protocol follow standard JSON-RPC 2.0 error handling:
7//! - Successful responses include a `result` field
8//! - Errors include an `error` object with `code` and `message`
9//! - Notifications never receive responses (success or error)
10//!
11//! See: [Error Handling](https://agentclientprotocol.com/protocol/overview#error-handling)
12
13use std::{fmt::Display, str};
14
15#[cfg(feature = "schemars")]
16use schemars::Schema;
17use serde::{Deserialize, Serialize};
18use serde_with::{DefaultOnError, serde_as, skip_serializing_none};
19
20use crate::IntoOption;
21
22/// Convenience result type using this protocol version's error type.
23pub type Result<T, E = Error> = std::result::Result<T, E>;
24
25/// JSON-RPC error object.
26///
27/// Represents an error that occurred during method execution, following the
28/// JSON-RPC 2.0 error object specification with optional additional data.
29///
30/// See protocol docs: [JSON-RPC Error Object](https://www.jsonrpc.org/specification#error_object)
31#[serde_as]
32#[skip_serializing_none]
33#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
34#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
35#[non_exhaustive]
36pub struct Error {
37    /// A number indicating the error type that occurred.
38    /// This must be an integer as defined in the JSON-RPC specification.
39    pub code: ErrorCode,
40    /// A string providing a short description of the error.
41    /// The message should be limited to a concise single sentence.
42    pub message: String,
43    /// Optional primitive or structured value that contains additional information about the error.
44    /// This may include debugging information or context-specific details.
45    #[serde_as(deserialize_as = "DefaultOnError")]
46    #[cfg_attr(feature = "schemars", schemars(extend("x-deserialize-default-on-error" = true)))]
47    #[serde(default)]
48    pub data: Option<serde_json::Value>,
49}
50
51impl Error {
52    /// Creates a new error with the given code and message.
53    ///
54    /// The code parameter can be an `ErrorCode` constant or a tuple of (code, message).
55    #[must_use]
56    pub fn new(code: i32, message: impl Into<String>) -> Self {
57        Error {
58            code: code.into(),
59            message: message.into(),
60            data: None,
61        }
62    }
63
64    /// Adds additional data to the error.
65    ///
66    /// This method is chainable and allows attaching context-specific information
67    /// to help with debugging or provide more details about the error.
68    #[must_use]
69    pub fn data(mut self, data: impl IntoOption<serde_json::Value>) -> Self {
70        self.data = data.into_option();
71        self
72    }
73
74    /// Invalid JSON was received by the server. An error occurred on the server while parsing the JSON text.
75    #[must_use]
76    pub fn parse_error() -> Self {
77        ErrorCode::ParseError.into()
78    }
79
80    /// The JSON sent is not a valid Request object.
81    #[must_use]
82    pub fn invalid_request() -> Self {
83        ErrorCode::InvalidRequest.into()
84    }
85
86    /// The method does not exist / is not available.
87    #[must_use]
88    pub fn method_not_found() -> Self {
89        ErrorCode::MethodNotFound.into()
90    }
91
92    /// Invalid method parameter(s).
93    #[must_use]
94    pub fn invalid_params() -> Self {
95        ErrorCode::InvalidParams.into()
96    }
97
98    /// Internal JSON-RPC error.
99    #[must_use]
100    pub fn internal_error() -> Self {
101        ErrorCode::InternalError.into()
102    }
103
104    /// Request was cancelled.
105    ///
106    /// Execution of the method was aborted either due to a cancellation request from the caller
107    /// or because of resource constraints or shutdown.
108    #[must_use]
109    pub fn request_cancelled() -> Self {
110        ErrorCode::RequestCancelled.into()
111    }
112
113    /// Authentication required.
114    #[must_use]
115    pub fn auth_required() -> Self {
116        ErrorCode::AuthRequired.into()
117    }
118
119    /// A given resource, such as a file, was not found.
120    #[must_use]
121    pub fn resource_not_found(uri: Option<String>) -> Self {
122        let err: Self = ErrorCode::ResourceNotFound.into();
123        if let Some(uri) = uri {
124            err.data(serde_json::json!({ "uri": uri }))
125        } else {
126            err
127        }
128    }
129
130    /// Converts a standard error into an internal JSON-RPC error.
131    ///
132    /// The error's string representation is included as additional data.
133    #[must_use]
134    pub fn into_internal_error(err: impl std::error::Error) -> Self {
135        Error::internal_error().data(err.to_string())
136    }
137}
138
139/// Predefined error codes for common JSON-RPC and ACP-specific errors.
140///
141/// These codes follow the JSON-RPC 2.0 specification for standard errors
142/// and use the reserved range (-32000 to -32099) for protocol-specific errors.
143#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
144#[derive(Clone, Copy, Deserialize, Eq, PartialEq, Serialize, strum::Display)]
145#[cfg_attr(test, derive(strum::EnumIter))]
146#[serde(from = "i32", into = "i32")]
147#[cfg_attr(feature = "schemars", schemars(!from, !into))]
148#[non_exhaustive]
149pub enum ErrorCode {
150    // Standard errors
151    /// Invalid JSON was received by the server.
152    /// An error occurred on the server while parsing the JSON text.
153    #[cfg_attr(feature = "schemars", schemars(transform = error_code_transform))]
154    #[strum(to_string = "Parse error")]
155    ParseError, // -32700
156    /// The JSON sent is not a valid Request object.
157    #[cfg_attr(feature = "schemars", schemars(transform = error_code_transform))]
158    #[strum(to_string = "Invalid request")]
159    InvalidRequest, // -32600
160    /// The method does not exist or is not available.
161    #[cfg_attr(feature = "schemars", schemars(transform = error_code_transform))]
162    #[strum(to_string = "Method not found")]
163    MethodNotFound, // -32601
164    /// Invalid method parameter(s).
165    #[cfg_attr(feature = "schemars", schemars(transform = error_code_transform))]
166    #[strum(to_string = "Invalid params")]
167    InvalidParams, // -32602
168    /// Internal JSON-RPC error.
169    /// Reserved for implementation-defined server errors.
170    #[cfg_attr(feature = "schemars", schemars(transform = error_code_transform))]
171    #[strum(to_string = "Internal error")]
172    InternalError, // -32603
173    /// Execution of the method was aborted either due to a cancellation request from the caller or
174    /// because of resource constraints or shutdown.
175    #[cfg_attr(feature = "schemars", schemars(transform = error_code_transform))]
176    #[strum(to_string = "Request cancelled")]
177    RequestCancelled, // -32800
178
179    // Custom errors
180    /// Authentication is required before this operation can be performed.
181    #[cfg_attr(feature = "schemars", schemars(transform = error_code_transform))]
182    #[strum(to_string = "Authentication required")]
183    AuthRequired, // -32000
184    /// A given resource, such as a file, was not found.
185    #[cfg_attr(feature = "schemars", schemars(transform = error_code_transform))]
186    #[strum(to_string = "Resource not found")]
187    ResourceNotFound, // -32002
188    /// Other undefined error code.
189    #[cfg_attr(feature = "schemars", schemars(untagged))]
190    #[strum(to_string = "Unknown error")]
191    Other(i32),
192}
193
194impl From<i32> for ErrorCode {
195    fn from(value: i32) -> Self {
196        match value {
197            -32700 => ErrorCode::ParseError,
198            -32600 => ErrorCode::InvalidRequest,
199            -32601 => ErrorCode::MethodNotFound,
200            -32602 => ErrorCode::InvalidParams,
201            -32603 => ErrorCode::InternalError,
202            -32800 => ErrorCode::RequestCancelled,
203            -32000 => ErrorCode::AuthRequired,
204            -32002 => ErrorCode::ResourceNotFound,
205            _ => ErrorCode::Other(value),
206        }
207    }
208}
209
210impl From<ErrorCode> for i32 {
211    fn from(value: ErrorCode) -> Self {
212        match value {
213            ErrorCode::ParseError => -32700,
214            ErrorCode::InvalidRequest => -32600,
215            ErrorCode::MethodNotFound => -32601,
216            ErrorCode::InvalidParams => -32602,
217            ErrorCode::InternalError => -32603,
218            ErrorCode::RequestCancelled => -32800,
219            ErrorCode::AuthRequired => -32000,
220            ErrorCode::ResourceNotFound => -32002,
221            ErrorCode::Other(value) => value,
222        }
223    }
224}
225
226impl std::fmt::Debug for ErrorCode {
227    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
228        write!(f, "{}: {self}", i32::from(*self))
229    }
230}
231
232#[cfg(feature = "schemars")]
233fn error_code_transform(schema: &mut Schema) {
234    let name = schema
235        .get("const")
236        .expect("Unexpected schema for ErrorCode")
237        .as_str()
238        .expect("unexpected type for schema");
239    let code = match name {
240        "ParseError" => ErrorCode::ParseError,
241        "InvalidRequest" => ErrorCode::InvalidRequest,
242        "MethodNotFound" => ErrorCode::MethodNotFound,
243        "InvalidParams" => ErrorCode::InvalidParams,
244        "InternalError" => ErrorCode::InternalError,
245        "RequestCancelled" => ErrorCode::RequestCancelled,
246        "AuthRequired" => ErrorCode::AuthRequired,
247        "ResourceNotFound" => ErrorCode::ResourceNotFound,
248        _ => panic!("Unexpected error code name {name}"),
249    };
250    let mut description = schema
251        .get("description")
252        .expect("Missing description")
253        .as_str()
254        .expect("Unexpected type for description")
255        .to_owned();
256    schema.insert("title".into(), code.to_string().into());
257    description.insert_str(0, &format!("**{code}**: "));
258    schema.insert("description".into(), description.into());
259    schema.insert("const".into(), i32::from(code).into());
260    schema.insert("type".into(), "integer".into());
261    schema.insert("format".into(), "int32".into());
262}
263
264impl From<ErrorCode> for Error {
265    fn from(error_code: ErrorCode) -> Self {
266        Error::new(error_code.into(), error_code.to_string())
267    }
268}
269
270impl std::error::Error for Error {}
271
272impl Display for Error {
273    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
274        if self.message.is_empty() {
275            write!(f, "{}", i32::from(self.code))?;
276        } else {
277            write!(f, "{}", self.message)?;
278        }
279
280        if let Some(data) = &self.data {
281            let pretty = serde_json::to_string_pretty(data).unwrap_or_else(|_| data.to_string());
282            write!(f, ": {pretty}")?;
283        }
284
285        Ok(())
286    }
287}
288
289impl From<anyhow::Error> for Error {
290    fn from(error: anyhow::Error) -> Self {
291        match error.downcast::<Self>() {
292            Ok(error) => error,
293            Err(error) => Error::into_internal_error(&*error),
294        }
295    }
296}
297
298impl From<serde_json::Error> for Error {
299    fn from(error: serde_json::Error) -> Self {
300        Error::invalid_params().data(error.to_string())
301    }
302}
303
304#[cfg(test)]
305mod tests {
306    use strum::IntoEnumIterator;
307
308    use super::*;
309
310    #[test]
311    fn serialize_error_code() {
312        assert_eq!(
313            serde_json::from_value::<ErrorCode>(serde_json::json!(-32700)).unwrap(),
314            ErrorCode::ParseError
315        );
316        assert_eq!(
317            serde_json::to_value(ErrorCode::ParseError).unwrap(),
318            serde_json::json!(-32700)
319        );
320
321        assert_eq!(
322            serde_json::from_value::<ErrorCode>(serde_json::json!(1)).unwrap(),
323            ErrorCode::Other(1)
324        );
325        assert_eq!(
326            serde_json::to_value(ErrorCode::Other(1)).unwrap(),
327            serde_json::json!(1)
328        );
329    }
330
331    #[test]
332    fn serialize_error_code_equality() {
333        // Make sure schema generation doesn't panic when enabled.
334        #[cfg(feature = "schemars")]
335        let _schema = schemars::schema_for!(ErrorCode);
336        for error in ErrorCode::iter() {
337            assert_eq!(
338                error,
339                serde_json::from_value(serde_json::to_value(error).unwrap()).unwrap()
340            );
341        }
342    }
343}
agent_client_protocol_schema/v2/error.rs

agent_client_protocol_schema/v2/
error.rs
