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source dump of claude code forked from oppi.li/claude-code
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4.5 kB · 136 lines
TypeScript
at main
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137/** * SDK MCP Transport Bridge * * This file implements a transport bridge that allows MCP servers running in the SDK process * to communicate with the Claude Code CLI process through control messages. * * ## Architecture Overview * * Unlike regular MCP servers that run as separate processes, SDK MCP servers run in-process * within the SDK. This requires a special transport mechanism to bridge communication between: * - The CLI process (where the MCP client runs) * - The SDK process (where the SDK MCP server runs) * * ## Message Flow * * ### CLI → SDK (via SdkControlClientTransport) * 1. CLI's MCP Client calls a tool → sends JSONRPC request to SdkControlClientTransport * 2. Transport wraps the message in a control request with server_name and request_id * 3. Control request is sent via stdout to the SDK process * 4. SDK's StructuredIO receives the control response and routes it back to the transport * 5. Transport unwraps the response and returns it to the MCP Client * * ### SDK → CLI (via SdkControlServerTransport) * 1. Query receives control request with MCP message and calls transport.onmessage * 2. MCP server processes the message and calls transport.send() with response * 3. Transport calls sendMcpMessage callback with the response * 4. Query's callback resolves the pending promise with the response * 5. Query returns the response to complete the control request * * ## Key Design Points * * - SdkControlClientTransport: StructuredIO tracks pending requests * - SdkControlServerTransport: Query tracks pending requests * - The control request wrapper includes server_name to route to the correct SDK server * - The system supports multiple SDK MCP servers running simultaneously * - Message IDs are preserved through the entire flow for proper correlation */
import type { Transport } from '@modelcontextprotocol/sdk/shared/transport.js'import type { JSONRPCMessage } from '@modelcontextprotocol/sdk/types.js'
/** * Callback function to send an MCP message and get the response */export type SendMcpMessageCallback = ( serverName: string, message: JSONRPCMessage,) => Promise<JSONRPCMessage>
/** * CLI-side transport for SDK MCP servers. * * This transport is used in the CLI process to bridge communication between: * - The CLI's MCP Client (which wants to call tools on SDK MCP servers) * - The SDK process (where the actual MCP server runs) * * It converts MCP protocol messages into control requests that can be sent * through stdout/stdin to the SDK process. */export class SdkControlClientTransport implements Transport { private isClosed = false
onclose?: () => void onerror?: (error: Error) => void onmessage?: (message: JSONRPCMessage) => void
constructor( private serverName: string, private sendMcpMessage: SendMcpMessageCallback, ) {}
async start(): Promise<void> {}
async send(message: JSONRPCMessage): Promise<void> { if (this.isClosed) { throw new Error('Transport is closed') }
// Send the message and wait for the response const response = await this.sendMcpMessage(this.serverName, message)
// Pass the response back to the MCP client if (this.onmessage) { this.onmessage(response) } }
async close(): Promise<void> { if (this.isClosed) { return } this.isClosed = true this.onclose?.() }}
/** * SDK-side transport for SDK MCP servers. * * This transport is used in the SDK process to bridge communication between: * - Control requests coming from the CLI (via stdin) * - The actual MCP server running in the SDK process * * It acts as a simple pass-through that forwards messages to the MCP server * and sends responses back via a callback. * * Note: Query handles all request/response correlation and async flow. */export class SdkControlServerTransport implements Transport { private isClosed = false
constructor(private sendMcpMessage: (message: JSONRPCMessage) => void) {}
onclose?: () => void onerror?: (error: Error) => void onmessage?: (message: JSONRPCMessage) => void
async start(): Promise<void> {}
async send(message: JSONRPCMessage): Promise<void> { if (this.isClosed) { throw new Error('Transport is closed') }
// Simply pass the response back through the callback this.sendMcpMessage(message) }
async close(): Promise<void> { if (this.isClosed) { return } this.isClosed = true this.onclose?.() }}