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Object.defineProperty(exports, "__esModule", { value: true });
exports.Protocol = exports.DEFAULT_REQUEST_TIMEOUT_MSEC = void 0;
exports.mergeCapabilities = mergeCapabilities;
const zod_compat_js_1 = require("../server/zod-compat.js");
const types_js_1 = require("../types.js");
const interfaces_js_1 = require("../experimental/tasks/interfaces.js");
const zod_json_schema_compat_js_1 = require("../server/zod-json-schema-compat.js");
/**
* The default request timeout, in miliseconds.
*/
exports.DEFAULT_REQUEST_TIMEOUT_MSEC = 60000;
/**
* Implements MCP protocol framing on top of a pluggable transport, including
* features like request/response linking, notifications, and progress.
*/
class Protocol {
constructor(_options) {
this._options = _options;
this._requestMessageId = 0;
this._requestHandlers = new Map();
this._requestHandlerAbortControllers = new Map();
this._notificationHandlers = new Map();
this._responseHandlers = new Map();
this._progressHandlers = new Map();
this._timeoutInfo = new Map();
this._pendingDebouncedNotifications = new Set();
// Maps task IDs to progress tokens to keep handlers alive after CreateTaskResult
this._taskProgressTokens = new Map();
this._requestResolvers = new Map();
this.setNotificationHandler(types_js_1.CancelledNotificationSchema, notification => {
this._oncancel(notification);
});
this.setNotificationHandler(types_js_1.ProgressNotificationSchema, notification => {
this._onprogress(notification);
});
this.setRequestHandler(types_js_1.PingRequestSchema,
// Automatic pong by default.
_request => ({}));
// Install task handlers if TaskStore is provided
this._taskStore = _options?.taskStore;
this._taskMessageQueue = _options?.taskMessageQueue;
if (this._taskStore) {
this.setRequestHandler(types_js_1.GetTaskRequestSchema, async (request, extra) => {
const task = await this._taskStore.getTask(request.params.taskId, extra.sessionId);
if (!task) {
throw new types_js_1.McpError(types_js_1.ErrorCode.InvalidParams, 'Failed to retrieve task: Task not found');
}
// Per spec: tasks/get responses SHALL NOT include related-task metadata
// as the taskId parameter is the source of truth
// @ts-expect-error SendResultT cannot contain GetTaskResult, but we include it in our derived types everywhere else
return {
...task
};
});
this.setRequestHandler(types_js_1.GetTaskPayloadRequestSchema, async (request, extra) => {
const handleTaskResult = async () => {
const taskId = request.params.taskId;
// Deliver queued messages
if (this._taskMessageQueue) {
let queuedMessage;
while ((queuedMessage = await this._taskMessageQueue.dequeue(taskId, extra.sessionId))) {
// Handle response and error messages by routing them to the appropriate resolver
if (queuedMessage.type === 'response' || queuedMessage.type === 'error') {
const message = queuedMessage.message;
const requestId = message.id;
// Lookup resolver in _requestResolvers map
const resolver = this._requestResolvers.get(requestId);
if (resolver) {
// Remove resolver from map after invocation
this._requestResolvers.delete(requestId);
// Invoke resolver with response or error
if (queuedMessage.type === 'response') {
resolver(message);
}
else {
// Convert JSONRPCError to McpError
const errorMessage = message;
const error = new types_js_1.McpError(errorMessage.error.code, errorMessage.error.message, errorMessage.error.data);
resolver(error);
}
}
else {
// Handle missing resolver gracefully with error logging
const messageType = queuedMessage.type === 'response' ? 'Response' : 'Error';
this._onerror(new Error(`${messageType} handler missing for request ${requestId}`));
}
// Continue to next message
continue;
}
// Send the message on the response stream by passing the relatedRequestId
// This tells the transport to write the message to the tasks/result response stream
await this._transport?.send(queuedMessage.message, { relatedRequestId: extra.requestId });
}
}
// Now check task status
const task = await this._taskStore.getTask(taskId, extra.sessionId);
if (!task) {
throw new types_js_1.McpError(types_js_1.ErrorCode.InvalidParams, `Task not found: ${taskId}`);
}
// Block if task is not terminal (we've already delivered all queued messages above)
if (!(0, interfaces_js_1.isTerminal)(task.status)) {
// Wait for status change or new messages
await this._waitForTaskUpdate(taskId, extra.signal);
// After waking up, recursively call to deliver any new messages or result
return await handleTaskResult();
}
// If task is terminal, return the result
if ((0, interfaces_js_1.isTerminal)(task.status)) {
const result = await this._taskStore.getTaskResult(taskId, extra.sessionId);
this._clearTaskQueue(taskId);
return {
...result,
_meta: {
...result._meta,
[types_js_1.RELATED_TASK_META_KEY]: {
taskId: taskId
}
}
};
}
return await handleTaskResult();
};
return await handleTaskResult();
});
this.setRequestHandler(types_js_1.ListTasksRequestSchema, async (request, extra) => {
try {
const { tasks, nextCursor } = await this._taskStore.listTasks(request.params?.cursor, extra.sessionId);
// @ts-expect-error SendResultT cannot contain ListTasksResult, but we include it in our derived types everywhere else
return {
tasks,
nextCursor,
_meta: {}
};
}
catch (error) {
throw new types_js_1.McpError(types_js_1.ErrorCode.InvalidParams, `Failed to list tasks: ${error instanceof Error ? error.message : String(error)}`);
}
});
this.setRequestHandler(types_js_1.CancelTaskRequestSchema, async (request, extra) => {
try {
// Get the current task to check if it's in a terminal state, in case the implementation is not atomic
const task = await this._taskStore.getTask(request.params.taskId, extra.sessionId);
if (!task) {
throw new types_js_1.McpError(types_js_1.ErrorCode.InvalidParams, `Task not found: ${request.params.taskId}`);
}
// Reject cancellation of terminal tasks
if ((0, interfaces_js_1.isTerminal)(task.status)) {
throw new types_js_1.McpError(types_js_1.ErrorCode.InvalidParams, `Cannot cancel task in terminal status: ${task.status}`);
}
await this._taskStore.updateTaskStatus(request.params.taskId, 'cancelled', 'Client cancelled task execution.', extra.sessionId);
this._clearTaskQueue(request.params.taskId);
const cancelledTask = await this._taskStore.getTask(request.params.taskId, extra.sessionId);
if (!cancelledTask) {
// Task was deleted during cancellation (e.g., cleanup happened)
throw new types_js_1.McpError(types_js_1.ErrorCode.InvalidParams, `Task not found after cancellation: ${request.params.taskId}`);
}
return {
_meta: {},
...cancelledTask
};
}
catch (error) {
// Re-throw McpError as-is
if (error instanceof types_js_1.McpError) {
throw error;
}
throw new types_js_1.McpError(types_js_1.ErrorCode.InvalidRequest, `Failed to cancel task: ${error instanceof Error ? error.message : String(error)}`);
}
});
}
}
async _oncancel(notification) {
if (!notification.params.requestId) {
return;
}
// Handle request cancellation
const controller = this._requestHandlerAbortControllers.get(notification.params.requestId);
controller?.abort(notification.params.reason);
}
_setupTimeout(messageId, timeout, maxTotalTimeout, onTimeout, resetTimeoutOnProgress = false) {
this._timeoutInfo.set(messageId, {
timeoutId: setTimeout(onTimeout, timeout),
startTime: Date.now(),
timeout,
maxTotalTimeout,
resetTimeoutOnProgress,
onTimeout
});
}
_resetTimeout(messageId) {
const info = this._timeoutInfo.get(messageId);
if (!info)
return false;
const totalElapsed = Date.now() - info.startTime;
if (info.maxTotalTimeout && totalElapsed >= info.maxTotalTimeout) {
this._timeoutInfo.delete(messageId);
throw types_js_1.McpError.fromError(types_js_1.ErrorCode.RequestTimeout, 'Maximum total timeout exceeded', {
maxTotalTimeout: info.maxTotalTimeout,
totalElapsed
});
}
clearTimeout(info.timeoutId);
info.timeoutId = setTimeout(info.onTimeout, info.timeout);
return true;
}
_cleanupTimeout(messageId) {
const info = this._timeoutInfo.get(messageId);
if (info) {
clearTimeout(info.timeoutId);
this._timeoutInfo.delete(messageId);
}
}
/**
* Attaches to the given transport, starts it, and starts listening for messages.
*
* The Protocol object assumes ownership of the Transport, replacing any callbacks that have already been set, and expects that it is the only user of the Transport instance going forward.
*/
async connect(transport) {
if (this._transport) {
throw new Error('Already connected to a transport. Call close() before connecting to a new transport, or use a separate Protocol instance per connection.');
}
this._transport = transport;
const _onclose = this.transport?.onclose;
this._transport.onclose = () => {
_onclose?.();
this._onclose();
};
const _onerror = this.transport?.onerror;
this._transport.onerror = (error) => {
_onerror?.(error);
this._onerror(error);
};
const _onmessage = this._transport?.onmessage;
this._transport.onmessage = (message, extra) => {
_onmessage?.(message, extra);
if ((0, types_js_1.isJSONRPCResultResponse)(message) || (0, types_js_1.isJSONRPCErrorResponse)(message)) {
this._onresponse(message);
}
else if ((0, types_js_1.isJSONRPCRequest)(message)) {
this._onrequest(message, extra);
}
else if ((0, types_js_1.isJSONRPCNotification)(message)) {
this._onnotification(message);
}
else {
this._onerror(new Error(`Unknown message type: ${JSON.stringify(message)}`));
}
};
await this._transport.start();
}
_onclose() {
const responseHandlers = this._responseHandlers;
this._responseHandlers = new Map();
this._progressHandlers.clear();
this._taskProgressTokens.clear();
this._pendingDebouncedNotifications.clear();
for (const info of this._timeoutInfo.values()) {
clearTimeout(info.timeoutId);
}
this._timeoutInfo.clear();
// Abort all in-flight request handlers so they stop sending messages
for (const controller of this._requestHandlerAbortControllers.values()) {
controller.abort();
}
this._requestHandlerAbortControllers.clear();
const error = types_js_1.McpError.fromError(types_js_1.ErrorCode.ConnectionClosed, 'Connection closed');
this._transport = undefined;
this.onclose?.();
for (const handler of responseHandlers.values()) {
handler(error);
}
}
_onerror(error) {
this.onerror?.(error);
}
_onnotification(notification) {
const handler = this._notificationHandlers.get(notification.method) ?? this.fallbackNotificationHandler;
// Ignore notifications not being subscribed to.
if (handler === undefined) {
return;
}
// Starting with Promise.resolve() puts any synchronous errors into the monad as well.
Promise.resolve()
.then(() => handler(notification))
.catch(error => this._onerror(new Error(`Uncaught error in notification handler: ${error}`)));
}
_onrequest(request, extra) {
const handler = this._requestHandlers.get(request.method) ?? this.fallbackRequestHandler;
// Capture the current transport at request time to ensure responses go to the correct client
const capturedTransport = this._transport;
// Extract taskId from request metadata if present (needed early for method not found case)
const relatedTaskId = request.params?._meta?.[types_js_1.RELATED_TASK_META_KEY]?.taskId;
if (handler === undefined) {
const errorResponse = {
jsonrpc: '2.0',
id: request.id,
error: {
code: types_js_1.ErrorCode.MethodNotFound,
message: 'Method not found'
}
};
// Queue or send the error response based on whether this is a task-related request
if (relatedTaskId && this._taskMessageQueue) {
this._enqueueTaskMessage(relatedTaskId, {
type: 'error',
message: errorResponse,
timestamp: Date.now()
}, capturedTransport?.sessionId).catch(error => this._onerror(new Error(`Failed to enqueue error response: ${error}`)));
}
else {
capturedTransport
?.send(errorResponse)
.catch(error => this._onerror(new Error(`Failed to send an error response: ${error}`)));
}
return;
}
const abortController = new AbortController();
this._requestHandlerAbortControllers.set(request.id, abortController);
const taskCreationParams = (0, types_js_1.isTaskAugmentedRequestParams)(request.params) ? request.params.task : undefined;
const taskStore = this._taskStore ? this.requestTaskStore(request, capturedTransport?.sessionId) : undefined;
const fullExtra = {
signal: abortController.signal,
sessionId: capturedTransport?.sessionId,
_meta: request.params?._meta,
sendNotification: async (notification) => {
if (abortController.signal.aborted)
return;
// Include related-task metadata if this request is part of a task
const notificationOptions = { relatedRequestId: request.id };
if (relatedTaskId) {
notificationOptions.relatedTask = { taskId: relatedTaskId };
}
await this.notification(notification, notificationOptions);
},
sendRequest: async (r, resultSchema, options) => {
if (abortController.signal.aborted) {
throw new types_js_1.McpError(types_js_1.ErrorCode.ConnectionClosed, 'Request was cancelled');
}
// Include related-task metadata if this request is part of a task
const requestOptions = { ...options, relatedRequestId: request.id };
if (relatedTaskId && !requestOptions.relatedTask) {
requestOptions.relatedTask = { taskId: relatedTaskId };
}
// Set task status to input_required when sending a request within a task context
// Use the taskId from options (explicit) or fall back to relatedTaskId (inherited)
const effectiveTaskId = requestOptions.relatedTask?.taskId ?? relatedTaskId;
if (effectiveTaskId && taskStore) {
await taskStore.updateTaskStatus(effectiveTaskId, 'input_required');
}
return await this.request(r, resultSchema, requestOptions);
},
authInfo: extra?.authInfo,
requestId: request.id,
requestInfo: extra?.requestInfo,
taskId: relatedTaskId,
taskStore: taskStore,
taskRequestedTtl: taskCreationParams?.ttl,
closeSSEStream: extra?.closeSSEStream,
closeStandaloneSSEStream: extra?.closeStandaloneSSEStream
};
// Starting with Promise.resolve() puts any synchronous errors into the monad as well.
Promise.resolve()
.then(() => {
// If this request asked for task creation, check capability first
if (taskCreationParams) {
// Check if the request method supports task creation
this.assertTaskHandlerCapability(request.method);
}
})
.then(() => handler(request, fullExtra))
.then(async (result) => {
if (abortController.signal.aborted) {
// Request was cancelled
return;
}
const response = {
result,
jsonrpc: '2.0',
id: request.id
};
// Queue or send the response based on whether this is a task-related request
if (relatedTaskId && this._taskMessageQueue) {
await this._enqueueTaskMessage(relatedTaskId, {
type: 'response',
message: response,
timestamp: Date.now()
}, capturedTransport?.sessionId);
}
else {
await capturedTransport?.send(response);
}
}, async (error) => {
if (abortController.signal.aborted) {
// Request was cancelled
return;
}
const errorResponse = {
jsonrpc: '2.0',
id: request.id,
error: {
code: Number.isSafeInteger(error['code']) ? error['code'] : types_js_1.ErrorCode.InternalError,
message: error.message ?? 'Internal error',
...(error['data'] !== undefined && { data: error['data'] })
}
};
// Queue or send the error response based on whether this is a task-related request
if (relatedTaskId && this._taskMessageQueue) {
await this._enqueueTaskMessage(relatedTaskId, {
type: 'error',
message: errorResponse,
timestamp: Date.now()
}, capturedTransport?.sessionId);
}
else {
await capturedTransport?.send(errorResponse);
}
})
.catch(error => this._onerror(new Error(`Failed to send response: ${error}`)))
.finally(() => {
// Only delete if the stored controller is still ours; after close()+connect(),
// a new connection may have reused the same request ID with a different controller.
if (this._requestHandlerAbortControllers.get(request.id) === abortController) {
this._requestHandlerAbortControllers.delete(request.id);
}
});
}
_onprogress(notification) {
const { progressToken, ...params } = notification.params;
const messageId = Number(progressToken);
const handler = this._progressHandlers.get(messageId);
if (!handler) {
this._onerror(new Error(`Received a progress notification for an unknown token: ${JSON.stringify(notification)}`));
return;
}
const responseHandler = this._responseHandlers.get(messageId);
const timeoutInfo = this._timeoutInfo.get(messageId);
if (timeoutInfo && responseHandler && timeoutInfo.resetTimeoutOnProgress) {
try {
this._resetTimeout(messageId);
}
catch (error) {
// Clean up if maxTotalTimeout was exceeded
this._responseHandlers.delete(messageId);
this._progressHandlers.delete(messageId);
this._cleanupTimeout(messageId);
responseHandler(error);
return;
}
}
handler(params);
}
_onresponse(response) {
const messageId = Number(response.id);
// Check if this is a response to a queued request
const resolver = this._requestResolvers.get(messageId);
if (resolver) {
this._requestResolvers.delete(messageId);
if ((0, types_js_1.isJSONRPCResultResponse)(response)) {
resolver(response);
}
else {
const error = new types_js_1.McpError(response.error.code, response.error.message, response.error.data);
resolver(error);
}
return;
}
const handler = this._responseHandlers.get(messageId);
if (handler === undefined) {
this._onerror(new Error(`Received a response for an unknown message ID: ${JSON.stringify(response)}`));
return;
}
this._responseHandlers.delete(messageId);
this._cleanupTimeout(messageId);
// Keep progress handler alive for CreateTaskResult responses
let isTaskResponse = false;
if ((0, types_js_1.isJSONRPCResultResponse)(response) && response.result && typeof response.result === 'object') {
const result = response.result;
if (result.task && typeof result.task === 'object') {
const task = result.task;
if (typeof task.taskId === 'string') {
isTaskResponse = true;
this._taskProgressTokens.set(task.taskId, messageId);
}
}
}
if (!isTaskResponse) {
this._progressHandlers.delete(messageId);
}
if ((0, types_js_1.isJSONRPCResultResponse)(response)) {
handler(response);
}
else {
const error = types_js_1.McpError.fromError(response.error.code, response.error.message, response.error.data);
handler(error);
}
}
get transport() {
return this._transport;
}
/**
* Closes the connection.
*/
async close() {
await this._transport?.close();
}
/**
* Sends a request and returns an AsyncGenerator that yields response messages.
* The generator is guaranteed to end with either a 'result' or 'error' message.
*
* @example
* ```typescript
* const stream = protocol.requestStream(request, resultSchema, options);
* for await (const message of stream) {
* switch (message.type) {
* case 'taskCreated':
* console.log('Task created:', message.task.taskId);
* break;
* case 'taskStatus':
* console.log('Task status:', message.task.status);
* break;
* case 'result':
* console.log('Final result:', message.result);
* break;
* case 'error':
* console.error('Error:', message.error);
* break;
* }
* }
* ```
*
* @experimental Use `client.experimental.tasks.requestStream()` to access this method.
*/
async *requestStream(request, resultSchema, options) {
const { task } = options ?? {};
// For non-task requests, just yield the result
if (!task) {
try {
const result = await this.request(request, resultSchema, options);
yield { type: 'result', result };
}
catch (error) {
yield {
type: 'error',
error: error instanceof types_js_1.McpError ? error : new types_js_1.McpError(types_js_1.ErrorCode.InternalError, String(error))
};
}
return;
}
// For task-augmented requests, we need to poll for status
// First, make the request to create the task
let taskId;
try {
// Send the request and get the CreateTaskResult
const createResult = await this.request(request, types_js_1.CreateTaskResultSchema, options);
// Extract taskId from the result
if (createResult.task) {
taskId = createResult.task.taskId;
yield { type: 'taskCreated', task: createResult.task };
}
else {
throw new types_js_1.McpError(types_js_1.ErrorCode.InternalError, 'Task creation did not return a task');
}
// Poll for task completion
while (true) {
// Get current task status
const task = await this.getTask({ taskId }, options);
yield { type: 'taskStatus', task };
// Check if task is terminal
if ((0, interfaces_js_1.isTerminal)(task.status)) {
if (task.status === 'completed') {
// Get the final result
const result = await this.getTaskResult({ taskId }, resultSchema, options);
yield { type: 'result', result };
}
else if (task.status === 'failed') {
yield {
type: 'error',
error: new types_js_1.McpError(types_js_1.ErrorCode.InternalError, `Task ${taskId} failed`)
};
}
else if (task.status === 'cancelled') {
yield {
type: 'error',
error: new types_js_1.McpError(types_js_1.ErrorCode.InternalError, `Task ${taskId} was cancelled`)
};
}
return;
}
// When input_required, call tasks/result to deliver queued messages
// (elicitation, sampling) via SSE and block until terminal
if (task.status === 'input_required') {
const result = await this.getTaskResult({ taskId }, resultSchema, options);
yield { type: 'result', result };
return;
}
// Wait before polling again
const pollInterval = task.pollInterval ?? this._options?.defaultTaskPollInterval ?? 1000;
await new Promise(resolve => setTimeout(resolve, pollInterval));
// Check if cancelled
options?.signal?.throwIfAborted();
}
}
catch (error) {
yield {
type: 'error',
error: error instanceof types_js_1.McpError ? error : new types_js_1.McpError(types_js_1.ErrorCode.InternalError, String(error))
};
}
}
/**
* Sends a request and waits for a response.
*
* Do not use this method to emit notifications! Use notification() instead.
*/
request(request, resultSchema, options) {
const { relatedRequestId, resumptionToken, onresumptiontoken, task, relatedTask } = options ?? {};
// Send the request
return new Promise((resolve, reject) => {
const earlyReject = (error) => {
reject(error);
};
if (!this._transport) {
earlyReject(new Error('Not connected'));
return;
}
if (this._options?.enforceStrictCapabilities === true) {
try {
this.assertCapabilityForMethod(request.method);
// If task creation is requested, also check task capabilities
if (task) {
this.assertTaskCapability(request.method);
}
}
catch (e) {
earlyReject(e);
return;
}
}
options?.signal?.throwIfAborted();
const messageId = this._requestMessageId++;
const jsonrpcRequest = {
...request,
jsonrpc: '2.0',
id: messageId
};
if (options?.onprogress) {
this._progressHandlers.set(messageId, options.onprogress);
jsonrpcRequest.params = {
...request.params,
_meta: {
...(request.params?._meta || {}),
progressToken: messageId
}
};
}
// Augment with task creation parameters if provided
if (task) {
jsonrpcRequest.params = {
...jsonrpcRequest.params,
task: task
};
}
// Augment with related task metadata if relatedTask is provided
if (relatedTask) {
jsonrpcRequest.params = {
...jsonrpcRequest.params,
_meta: {
...(jsonrpcRequest.params?._meta || {}),
[types_js_1.RELATED_TASK_META_KEY]: relatedTask
}
};
}
const cancel = (reason) => {
this._responseHandlers.delete(messageId);
this._progressHandlers.delete(messageId);
this._cleanupTimeout(messageId);
this._transport
?.send({
jsonrpc: '2.0',
method: 'notifications/cancelled',
params: {
requestId: messageId,
reason: String(reason)
}
}, { relatedRequestId, resumptionToken, onresumptiontoken })
.catch(error => this._onerror(new Error(`Failed to send cancellation: ${error}`)));
// Wrap the reason in an McpError if it isn't already
const error = reason instanceof types_js_1.McpError ? reason : new types_js_1.McpError(types_js_1.ErrorCode.RequestTimeout, String(reason));
reject(error);
};
this._responseHandlers.set(messageId, response => {
if (options?.signal?.aborted) {
return;
}
if (response instanceof Error) {
return reject(response);
}
try {
const parseResult = (0, zod_compat_js_1.safeParse)(resultSchema, response.result);
if (!parseResult.success) {
// Type guard: if success is false, error is guaranteed to exist
reject(parseResult.error);
}
else {
resolve(parseResult.data);
}
}
catch (error) {
reject(error);
}
});
options?.signal?.addEventListener('abort', () => {
cancel(options?.signal?.reason);
});
const timeout = options?.timeout ?? exports.DEFAULT_REQUEST_TIMEOUT_MSEC;
const timeoutHandler = () => cancel(types_js_1.McpError.fromError(types_js_1.ErrorCode.RequestTimeout, 'Request timed out', { timeout }));
this._setupTimeout(messageId, timeout, options?.maxTotalTimeout, timeoutHandler, options?.resetTimeoutOnProgress ?? false);
// Queue request if related to a task
const relatedTaskId = relatedTask?.taskId;
if (relatedTaskId) {
// Store the response resolver for this request so responses can be routed back
const responseResolver = (response) => {
const handler = this._responseHandlers.get(messageId);
if (handler) {
handler(response);
}
else {
// Log error when resolver is missing, but don't fail
this._onerror(new Error(`Response handler missing for side-channeled request ${messageId}`));
}
};
this._requestResolvers.set(messageId, responseResolver);
this._enqueueTaskMessage(relatedTaskId, {
type: 'request',
message: jsonrpcRequest,
timestamp: Date.now()
}).catch(error => {
this._cleanupTimeout(messageId);
reject(error);
});
// Don't send through transport - queued messages are delivered via tasks/result only
// This prevents duplicate delivery for bidirectional transports
}
else {
// No related task - send through transport normally
this._transport.send(jsonrpcRequest, { relatedRequestId, resumptionToken, onresumptiontoken }).catch(error => {
this._cleanupTimeout(messageId);
reject(error);
});
}
});
}
/**
* Gets the current status of a task.
*
* @experimental Use `client.experimental.tasks.getTask()` to access this method.
*/
async getTask(params, options) {
// @ts-expect-error SendRequestT cannot directly contain GetTaskRequest, but we ensure all type instantiations contain it anyways
return this.request({ method: 'tasks/get', params }, types_js_1.GetTaskResultSchema, options);
}
/**
* Retrieves the result of a completed task.
*
* @experimental Use `client.experimental.tasks.getTaskResult()` to access this method.
*/
async getTaskResult(params, resultSchema, options) {
// @ts-expect-error SendRequestT cannot directly contain GetTaskPayloadRequest, but we ensure all type instantiations contain it anyways
return this.request({ method: 'tasks/result', params }, resultSchema, options);
}
/**
* Lists tasks, optionally starting from a pagination cursor.
*
* @experimental Use `client.experimental.tasks.listTasks()` to access this method.
*/
async listTasks(params, options) {
// @ts-expect-error SendRequestT cannot directly contain ListTasksRequest, but we ensure all type instantiations contain it anyways
return this.request({ method: 'tasks/list', params }, types_js_1.ListTasksResultSchema, options);
}
/**
* Cancels a specific task.
*
* @experimental Use `client.experimental.tasks.cancelTask()` to access this method.
*/
async cancelTask(params, options) {
// @ts-expect-error SendRequestT cannot directly contain CancelTaskRequest, but we ensure all type instantiations contain it anyways
return this.request({ method: 'tasks/cancel', params }, types_js_1.CancelTaskResultSchema, options);
}
/**
* Emits a notification, which is a one-way message that does not expect a response.
*/
async notification(notification, options) {
if (!this._transport) {
throw new Error('Not connected');
}
this.assertNotificationCapability(notification.method);
// Queue notification if related to a task
const relatedTaskId = options?.relatedTask?.taskId;
if (relatedTaskId) {
// Build the JSONRPC notification with metadata
const jsonrpcNotification = {
...notification,
jsonrpc: '2.0',
params: {
...notification.params,
_meta: {
...(notification.params?._meta || {}),
[types_js_1.RELATED_TASK_META_KEY]: options.relatedTask
}
}
};
await this._enqueueTaskMessage(relatedTaskId, {
type: 'notification',
message: jsonrpcNotification,
timestamp: Date.now()
});
// Don't send through transport - queued messages are delivered via tasks/result only
// This prevents duplicate delivery for bidirectional transports
return;
}
const debouncedMethods = this._options?.debouncedNotificationMethods ?? [];
// A notification can only be debounced if it's in the list AND it's "simple"
// (i.e., has no parameters and no related request ID or related task that could be lost).
const canDebounce = debouncedMethods.includes(notification.method) && !notification.params && !options?.relatedRequestId && !options?.relatedTask;
if (canDebounce) {
// If a notification of this type is already scheduled, do nothing.
if (this._pendingDebouncedNotifications.has(notification.method)) {
return;
}
// Mark this notification type as pending.
this._pendingDebouncedNotifications.add(notification.method);
// Schedule the actual send to happen in the next microtask.
// This allows all synchronous calls in the current event loop tick to be coalesced.
Promise.resolve().then(() => {
// Un-mark the notification so the next one can be scheduled.
this._pendingDebouncedNotifications.delete(notification.method);
// SAFETY CHECK: If the connection was closed while this was pending, abort.
if (!this._transport) {
return;
}
let jsonrpcNotification = {
...notification,
jsonrpc: '2.0'
};
// Augment with related task metadata if relatedTask is provided
if (options?.relatedTask) {
jsonrpcNotification = {
...jsonrpcNotification,
params: {
...jsonrpcNotification.params,
_meta: {
...(jsonrpcNotification.params?._meta || {}),
[types_js_1.RELATED_TASK_META_KEY]: options.relatedTask
}
}
};
}
// Send the notification, but don't await it here to avoid blocking.
// Handle potential errors with a .catch().
this._transport?.send(jsonrpcNotification, options).catch(error => this._onerror(error));
});
// Return immediately.
return;
}
let jsonrpcNotification = {
...notification,
jsonrpc: '2.0'
};
// Augment with related task metadata if relatedTask is provided
if (options?.relatedTask) {
jsonrpcNotification = {
...jsonrpcNotification,
params: {
...jsonrpcNotification.params,
_meta: {
...(jsonrpcNotification.params?._meta || {}),
[types_js_1.RELATED_TASK_META_KEY]: options.relatedTask
}
}
};
}
await this._transport.send(jsonrpcNotification, options);
}
/**
* Registers a handler to invoke when this protocol object receives a request with the given method.
*
* Note that this will replace any previous request handler for the same method.
*/
setRequestHandler(requestSchema, handler) {
const method = (0, zod_json_schema_compat_js_1.getMethodLiteral)(requestSchema);
this.assertRequestHandlerCapability(method);
this._requestHandlers.set(method, (request, extra) => {
const parsed = (0, zod_json_schema_compat_js_1.parseWithCompat)(requestSchema, request);
return Promise.resolve(handler(parsed, extra));
});
}
/**
* Removes the request handler for the given method.
*/
removeRequestHandler(method) {
this._requestHandlers.delete(method);
}
/**
* Asserts that a request handler has not already been set for the given method, in preparation for a new one being automatically installed.
*/
assertCanSetRequestHandler(method) {
if (this._requestHandlers.has(method)) {
throw new Error(`A request handler for ${method} already exists, which would be overridden`);
}
}
/**
* Registers a handler to invoke when this protocol object receives a notification with the given method.
*
* Note that this will replace any previous notification handler for the same method.
*/
setNotificationHandler(notificationSchema, handler) {
const method = (0, zod_json_schema_compat_js_1.getMethodLiteral)(notificationSchema);
this._notificationHandlers.set(method, notification => {
const parsed = (0, zod_json_schema_compat_js_1.parseWithCompat)(notificationSchema, notification);
return Promise.resolve(handler(parsed));
});
}
/**
* Removes the notification handler for the given method.
*/
removeNotificationHandler(method) {
this._notificationHandlers.delete(method);
}
/**
* Cleans up the progress handler associated with a task.
* This should be called when a task reaches a terminal status.
*/
_cleanupTaskProgressHandler(taskId) {
const progressToken = this._taskProgressTokens.get(taskId);
if (progressToken !== undefined) {
this._progressHandlers.delete(progressToken);
this._taskProgressTokens.delete(taskId);
}
}
/**
* Enqueues a task-related message for side-channel delivery via tasks/result.
* @param taskId The task ID to associate the message with
* @param message The message to enqueue
* @param sessionId Optional session ID for binding the operation to a specific session
* @throws Error if taskStore is not configured or if enqueue fails (e.g., queue overflow)
*
* Note: If enqueue fails, it's the TaskMessageQueue implementation's responsibility to handle
* the error appropriately (e.g., by failing the task, logging, etc.). The Protocol layer
* simply propagates the error.
*/
async _enqueueTaskMessage(taskId, message, sessionId) {
// Task message queues are only used when taskStore is configured
if (!this._taskStore || !this._taskMessageQueue) {
throw new Error('Cannot enqueue task message: taskStore and taskMessageQueue are not configured');
}
const maxQueueSize = this._options?.maxTaskQueueSize;
await this._taskMessageQueue.enqueue(taskId, message, sessionId, maxQueueSize);
}
/**
* Clears the message queue for a task and rejects any pending request resolvers.
* @param taskId The task ID whose queue should be cleared
* @param sessionId Optional session ID for binding the operation to a specific session
*/
async _clearTaskQueue(taskId, sessionId) {
if (this._taskMessageQueue) {
// Reject any pending request resolvers
const messages = await this._taskMessageQueue.dequeueAll(taskId, sessionId);
for (const message of messages) {
if (message.type === 'request' && (0, types_js_1.isJSONRPCRequest)(message.message)) {
// Extract request ID from the message
const requestId = message.message.id;
const resolver = this._requestResolvers.get(requestId);
if (resolver) {
resolver(new types_js_1.McpError(types_js_1.ErrorCode.InternalError, 'Task cancelled or completed'));
this._requestResolvers.delete(requestId);
}
else {
// Log error when resolver is missing during cleanup for better observability
this._onerror(new Error(`Resolver missing for request ${requestId} during task ${taskId} cleanup`));
}
}
}
}
}
/**
* Waits for a task update (new messages or status change) with abort signal support.
* Uses polling to check for updates at the task's configured poll interval.
* @param taskId The task ID to wait for
* @param signal Abort signal to cancel the wait
* @returns Promise that resolves when an update occurs or rejects if aborted
*/
async _waitForTaskUpdate(taskId, signal) {
// Get the task's poll interval, falling back to default
let interval = this._options?.defaultTaskPollInterval ?? 1000;
try {
const task = await this._taskStore?.getTask(taskId);
if (task?.pollInterval) {
interval = task.pollInterval;
}
}
catch {
// Use default interval if task lookup fails
}
return new Promise((resolve, reject) => {
if (signal.aborted) {
reject(new types_js_1.McpError(types_js_1.ErrorCode.InvalidRequest, 'Request cancelled'));
return;
}
// Wait for the poll interval, then resolve so caller can check for updates
const timeoutId = setTimeout(resolve, interval);
// Clean up timeout and reject if aborted
signal.addEventListener('abort', () => {
clearTimeout(timeoutId);
reject(new types_js_1.McpError(types_js_1.ErrorCode.InvalidRequest, 'Request cancelled'));
}, { once: true });
});
}
requestTaskStore(request, sessionId) {
const taskStore = this._taskStore;
if (!taskStore) {
throw new Error('No task store configured');
}
return {
createTask: async (taskParams) => {
if (!request) {
throw new Error('No request provided');
}
return await taskStore.createTask(taskParams, request.id, {
method: request.method,
params: request.params
}, sessionId);
},
getTask: async (taskId) => {
const task = await taskStore.getTask(taskId, sessionId);
if (!task) {
throw new types_js_1.McpError(types_js_1.ErrorCode.InvalidParams, 'Failed to retrieve task: Task not found');
}
return task;
},
storeTaskResult: async (taskId, status, result) => {
await taskStore.storeTaskResult(taskId, status, result, sessionId);
// Get updated task state and send notification
const task = await taskStore.getTask(taskId, sessionId);
if (task) {
const notification = types_js_1.TaskStatusNotificationSchema.parse({
method: 'notifications/tasks/status',
params: task
});
await this.notification(notification);
if ((0, interfaces_js_1.isTerminal)(task.status)) {
this._cleanupTaskProgressHandler(taskId);
// Don't clear queue here - it will be cleared after delivery via tasks/result
}
}
},
getTaskResult: taskId => {
return taskStore.getTaskResult(taskId, sessionId);
},
updateTaskStatus: async (taskId, status, statusMessage) => {
// Check if task exists
const task = await taskStore.getTask(taskId, sessionId);
if (!task) {
throw new types_js_1.McpError(types_js_1.ErrorCode.InvalidParams, `Task "${taskId}" not found - it may have been cleaned up`);
}
// Don't allow transitions from terminal states
if ((0, interfaces_js_1.isTerminal)(task.status)) {
throw new types_js_1.McpError(types_js_1.ErrorCode.InvalidParams, `Cannot update task "${taskId}" from terminal status "${task.status}" to "${status}". Terminal states (completed, failed, cancelled) cannot transition to other states.`);
}
await taskStore.updateTaskStatus(taskId, status, statusMessage, sessionId);
// Get updated task state and send notification
const updatedTask = await taskStore.getTask(taskId, sessionId);
if (updatedTask) {
const notification = types_js_1.TaskStatusNotificationSchema.parse({
method: 'notifications/tasks/status',
params: updatedTask
});
await this.notification(notification);
if ((0, interfaces_js_1.isTerminal)(updatedTask.status)) {
this._cleanupTaskProgressHandler(taskId);
// Don't clear queue here - it will be cleared after delivery via tasks/result
}
}
},
listTasks: cursor => {
return taskStore.listTasks(cursor, sessionId);
}
};
}
}
exports.Protocol = Protocol;
function isPlainObject(value) {
return value !== null && typeof value === 'object' && !Array.isArray(value);
}
function mergeCapabilities(base, additional) {
const result = { ...base };
for (const key in additional) {
const k = key;
const addValue = additional[k];
if (addValue === undefined)
continue;
const baseValue = result[k];
if (isPlainObject(baseValue) && isPlainObject(addValue)) {
result[k] = { ...baseValue, ...addValue };
}
else {
result[k] = addValue;
}
}
return result;
}
//# sourceMappingURL=protocol.js.map |