mcp-stdio-core -- JSON-RPC stdio Framing + Dispatch (Core)

Generated: 2026-08-24 / f3642fcda

OVERVIEW

The lowest-level core package: JSON-RPC 2.0 transport over stdio (line-mode and Content-Length framed), an event-loop server with idle timeout, response builders, and an isPlainRecord guard. Zero runtime/peer dependencies; imports nothing from the workspace, consumed by every MCP-layer package. Package: @oh-my-opencode/mcp-stdio-core.

KEY FILES (5 source, all flat in src/)

File	Subpath export	Role
types.ts	./types	JsonRpcId/Error/Result/Response, McpToolDescriptor, TextContent, McpLifecycleLog
record.ts	./record	isPlainRecord(value) type guard
responses.ts	./responses	successResponse, errorResponse, jsonRpcId, messageFromError
server.ts	./server	runJsonRpcStdioServer(config): async-generator loop, idle timeout, McpRequestHandler, exits on terminal output errors
transport.ts	./transport	readStdioJsonRpcMessages (async gen), writeStdioJsonRpcResponse, dual framing

CONSUMERS

• lsp-core/src/mcp.ts (primary): LSP MCP server.
• ast-grep-mcp/src/mcp.ts: ast-grep MCP server.
• git-bash-mcp/src/mcp.ts: Git Bash MCP server.
• lsp-daemon/src/proxy.ts: stdio MCP proxy; also imports ./record from daemon-client.ts, request-routing.ts, ipc-protocol.ts.

NOTES

• Two framing modes: "line" (\n-delimited) and "framed" (Content-Length: header per MCP spec); auto-detected by scanning the buffer prefix for content-length:.
• Idle timeout uses timer.unref(): the timeout never keeps the process alive.
• Handler contract: return undefined to skip silently; onHandlerError catches exceptions; parseErrorResponse customizes JSON parse errors.
• Output writes are awaited; closed output stops the loop: writeStdioJsonRpcResponse is async and writeChunk removes its one-shot error listener after settle. writeResponse catches terminal output errors (EPIPE, ERR_STREAM_DESTROYED, ERR_STREAM_WRITE_AFTER_END), logs output_error, and returns false so the read loop exits; non-terminal write errors still propagate.
• Keep zero dependencies. .js suffix on relative imports (ESM). This is the floor of the package layering; it must stay leaf.
• Parent: packages/AGENTS.md.