@chttp/mcp

@chttp/mcp

Model Context Protocol server (JSON-RPC 2.0, spec revision 2025-06-18) authored in the scriptc-compilable subset — the same source builds to a JS package with tsc and lowers into a native ELF with scriptc build. Zero runtime dependencies.

import { Server, StreamableHttpTransport, tool } from "@chttp/mcp";
import * as v from "@chttp/val";

const server = new Server({
  name: "my-server",
  version: "0.1.0",
  emitJsonSchema: (s) => v.toJsonSchema(s),
});

tool(server, "add", v.object({ a: v.number(), b: v.number() }), async (i) =>
  String(i.a + i.b),
);

export default { fetch: StreamableHttpTransport.route(server) };

What it does

• Server — tool/resource/prompt registration plus handleRequest(JsonRpcRequest) covering the full MCP method table (initialize, ping, tools/list, tools/call, resources/*, prompts/*, notifications/*, logging/setLevel, completion/complete).
• Two injected seams: validation runs through schema["~standard"].validate (any Standard Schema validator — @chttp/val, valibot, zod); JSON Schema emission is an adapter you pass (emitJsonSchema), so no schema code ships in the package.
• Auto-wrap ladder for tool returns: strings become text blocks, plain objects become dual content + structuredContent, a full CallToolResult passes through, thrown errors become isError results.
• StreamableHttpTransport — POST JSON-RPC plus an SSE stream (GET ?stream=progress) carrying notifications/progress/notifications/message while tools run.
• Progress + log notifications through a server-level sink registry (ctx.progress, ctx.log, logging/setLevel severity filter).

Docs

Per-package pages live under packages/mcp/docs/: integration, schema seams, transports, Streamable-HTTP coverage (what v1 does and deliberately skips), the auto-wrap ladder, and scriptc-subset authoring notes. Examples: packages/mcp/examples/todo-mcp and examples/integrations/mcp-stdio.

Status

v0.1.0. Covers spec revision 2025-06-18 for tools/resources/prompts + streamable-HTTP POST/SSE. Sessions, resumability, batching, roots/sampling/elicitation, and a packaged stdio transport are out of scope by design — see docs/streamable-http-coverage.md.