8 Commits

Author SHA1 Message Date
1e034412ca Bump a2amcp to 0.1.7
All checks were successful
build / test (push) Successful in 19s
publish / npm (push) Successful in 22s
2026-05-31 19:56:29 -03:00
bbc7f593b1 Document hosted OAuth MCP connectors
All checks were successful
build / test (push) Successful in 19s
2026-05-31 19:26:02 -03:00
b0dd1fa28d Commit pending workspace updates
All checks were successful
build / test (push) Successful in 31s
2026-05-28 20:25:06 -03:00
91c7bf9c57 WIP a2a-mcp updates
All checks were successful
build / test (push) Successful in 30s
2026-05-23 14:33:03 -04:00
4ff51157c0 Relay upstream MCP elicitation
All checks were successful
build / test (push) Successful in 31s
2026-05-23 13:32:25 -04:00
2fd97d8d09 Handle upstream stream drops
All checks were successful
build / test (push) Successful in 29s
2026-05-23 12:20:22 -04:00
45e12324df release: 0.1.6 — relay notifications/progress to MCP client
All checks were successful
build / test (push) Successful in 30s
publish / npm (push) Successful in 33s
Long-running upstream skills emit MCP notifications/progress on the SSE
stream. Without forwarding, the gateway swallows them and the MCP
client (Claude Code, Cursor) aborts the tools/call on its idle timer
after ~60s — even though the HTTP stream stays warm.

Gateway now passes the SDK's extra.sendNotification through to
UpstreamAgent.callTool. Any non-response frame with a method but no id
becomes a notification on the client side. Each tools/call carries a
progressToken (client-supplied or request-id fallback) so the client
can correlate.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-15 21:37:58 -03:00
09b588326c release: 0.1.5 — SSE-stream tools/call to dodge ingress timeout
All checks were successful
build / test (push) Successful in 28s
publish / npm (push) Successful in 32s
agent-builder.build (and any long-running skill) takes minutes — LLM
loop + sandbox tests + deploy + wait-for-live-card. A plain JSON POST
to /mcp gets killed by ingress idle timeouts (~60s on traefik) and the
gateway sees "fetch failed" while the upstream is still running.

UpstreamAgent.callTool now negotiates ``Accept: text/event-stream`` on
tools/call. We drain SSE frames, return the final tools/call result,
and fall back to plain JSON if the upstream doesn't speak SSE (older
a2a-pack). Elicit relaying isn't wired yet; for now any
elicitation/create frame is ignored.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-15 21:12:53 -03:00
10 changed files with 617 additions and 30 deletions

1
.gitignore vendored
View File

@@ -1,5 +1,6 @@
node_modules/ node_modules/
dist/ dist/
.codegraph/
*.log *.log
*.tsbuildinfo *.tsbuildinfo
.DS_Store .DS_Store

View File

@@ -4,6 +4,21 @@ MCP gateway for a2acloud agents. It runs locally as a stdio MCP server and
exposes deployed A2A agents as tools to Claude Code, Cursor, and other MCP exposes deployed A2A agents as tools to Claude Code, Cursor, and other MCP
clients. clients.
This package is the **local stdio gateway**. It is different from the hosted
OAuth MCP connector endpoints used by ChatGPT/Claude web connectors:
```text
Local stdio gateway: npx -y a2amcp
Remote standard MCP: https://<agent>.a2acloud.io/mcp
Remote connector MCP: https://<agent>.a2acloud.io/connector-mcp
Remote orchestrator MCP: https://api.a2acloud.io/connector-mcp
```
Use `a2amcp` for editor clients that launch a local MCP server process. Use the
remote `/connector-mcp` URL for hosted connector UIs that need OAuth login,
Dynamic Client Registration, async job polling, and structured approval/input
interrupts.
## Quickstart ## Quickstart
```bash ```bash
@@ -41,3 +56,19 @@ a2amcp logout # clear local credentials
``` ```
Running `a2amcp` with no command starts the MCP gateway over stdio. Running `a2amcp` with no command starts the MCP gateway over stdio.
## Hosted OAuth Connectors
ChatGPT and Claude-style hosted connectors should not run this stdio gateway.
Configure them directly with the remote connector URL:
```text
https://api.a2acloud.io/connector-mcp
https://<agent>.a2acloud.io/connector-mcp
```
Choose OAuth authentication. The server advertises protected-resource metadata,
the client dynamically registers with Keycloak, and the browser consent flow
issues tokens scoped to MCP access. Long-running connector calls return a
`job_id`; the client should poll `chat_result` on the orchestrator connector or
`job_result` on a leaf-agent connector.

4
package-lock.json generated
View File

@@ -1,12 +1,12 @@
{ {
"name": "a2amcp", "name": "a2amcp",
"version": "0.1.4", "version": "0.1.7",
"lockfileVersion": 3, "lockfileVersion": 3,
"requires": true, "requires": true,
"packages": { "packages": {
"": { "": {
"name": "a2amcp", "name": "a2amcp",
"version": "0.1.4", "version": "0.1.7",
"license": "Apache-2.0", "license": "Apache-2.0",
"dependencies": { "dependencies": {
"@modelcontextprotocol/sdk": "^1.0.4", "@modelcontextprotocol/sdk": "^1.0.4",

View File

@@ -1,6 +1,6 @@
{ {
"name": "a2amcp", "name": "a2amcp",
"version": "0.1.4", "version": "0.1.7",
"description": "MCP gateway for a2acloud agents. Run as a local MCP server; expose any number of deployed A2A agents to Claude Code, Cursor, and other MCP clients.", "description": "MCP gateway for a2acloud agents. Run as a local MCP server; expose any number of deployed A2A agents to Claude Code, Cursor, and other MCP clients.",
"type": "module", "type": "module",
"bin": { "bin": {

View File

@@ -15,6 +15,7 @@ export interface AgentRow {
status: string; status: string;
url?: string; url?: string;
description?: string; description?: string;
card?: Record<string, any>;
} }
export class ControlPlaneClient { export class ControlPlaneClient {

View File

@@ -43,6 +43,30 @@ function fail(msg: string, code = 1): never {
process.exit(code); process.exit(code);
} }
function normalizeMcpPath(path: unknown): string {
if (typeof path !== "string" || !path.trim()) return "/mcp";
const trimmed = path.trim();
return trimmed.startsWith("/") ? trimmed : `/${trimmed}`;
}
function mcpTargetForAgent(
row: { name: string; url?: string; card?: Record<string, any> },
apiUrl: string,
): { url?: string; mcpPath: string } {
const imported = row.card?.capabilities?.a2a_cloud_import;
const mcp = imported?.mcp;
if (mcp?.mode === "generated") {
return {
url: `${apiUrl.replace(/\/+$/, "")}/v1/agents/${encodeURIComponent(row.name)}`,
mcpPath: normalizeMcpPath(mcp.path),
};
}
return {
url: mcp?.base_url || row.url,
mcpPath: normalizeMcpPath(mcp?.path || row.card?.mcp_endpoint),
};
}
async function prompt(label: string, opts: { hidden?: boolean } = {}): Promise<string> { async function prompt(label: string, opts: { hidden?: boolean } = {}): Promise<string> {
const rl = readline.createInterface({ input, output, terminal: true }); const rl = readline.createInterface({ input, output, terminal: true });
try { try {
@@ -160,7 +184,9 @@ program
output.write("(no agents added; try `a2amcp add <name>`)\n"); output.write("(no agents added; try `a2amcp add <name>`)\n");
return; return;
} }
for (const a of cfg.agents) output.write(` ${a.name} ${a.url}\n`); for (const a of cfg.agents) {
output.write(` ${a.name} ${a.url}${a.mcpPath ?? "/mcp"}\n`);
}
}); });
program program
@@ -171,11 +197,16 @@ program
.action( .action(
async (name: string, opts: { url?: string; api?: string }) => { async (name: string, opts: { url?: string; api?: string }) => {
let url = opts.url; let url = opts.url;
let mcpPath = "/mcp";
let description: string | undefined; let description: string | undefined;
if (!url) { if (!url) {
try { try {
const row = await (await client(opts.api)).getAgent(name); const creds = await loadCredentials();
url = row.url; const apiUrl = resolveApiUrl(opts.api ?? creds?.apiUrl);
const row = await new ControlPlaneClient(apiUrl, creds?.token ?? null).getAgent(name);
const target = mcpTargetForAgent(row, apiUrl);
url = target.url;
mcpPath = target.mcpPath;
description = row.description; description = row.description;
} catch (err) { } catch (err) {
fail(err instanceof ApiError ? err.message : (err as Error).message); fail(err instanceof ApiError ? err.message : (err as Error).message);
@@ -185,10 +216,11 @@ program
await addAgent({ await addAgent({
name, name,
url, url,
mcpPath,
description, description,
addedAt: new Date().toISOString(), addedAt: new Date().toISOString(),
}); });
output.write(`added ${name} -> ${url}\n`); output.write(`added ${name} -> ${url.replace(/\/+$/, "")}${mcpPath}\n`);
output.write("restart your MCP client to pick up the new tools.\n"); output.write("restart your MCP client to pick up the new tools.\n");
}, },
); );
@@ -219,6 +251,7 @@ program
const u = new UpstreamAgent({ const u = new UpstreamAgent({
name: a.name, name: a.name,
url: a.url, url: a.url,
mcpPath: a.mcpPath,
token: creds?.token ?? null, token: creds?.token ?? null,
}); });
try { try {

View File

@@ -12,6 +12,7 @@ import path from "node:path";
export interface EnabledAgent { export interface EnabledAgent {
name: string; name: string;
url: string; url: string;
mcpPath?: string;
description?: string; description?: string;
addedAt: string; addedAt: string;
} }

View File

@@ -11,7 +11,9 @@ import { Server } from "@modelcontextprotocol/sdk/server/index.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js"; import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { import {
CallToolRequestSchema, CallToolRequestSchema,
ElicitResultSchema,
ListToolsRequestSchema, ListToolsRequestSchema,
ResultSchema,
} from "@modelcontextprotocol/sdk/types.js"; } from "@modelcontextprotocol/sdk/types.js";
import { loadConfig, type EnabledAgent } from "./config.js"; import { loadConfig, type EnabledAgent } from "./config.js";
@@ -28,6 +30,10 @@ export interface GatewayOptions {
agents?: EnabledAgent[]; agents?: EnabledAgent[];
/** Override the bearer token (otherwise read from ~/.a2a/credentials.json). */ /** Override the bearer token (otherwise read from ~/.a2a/credentials.json). */
token?: string | null; token?: string | null;
/** Test/advanced override for one-shot upstream JSON-RPC calls. */
upstreamRequestTimeoutMs?: number;
/** Test/advanced override for idle SSE upstream tools/call streams. */
upstreamStreamIdleTimeoutMs?: number;
/** Optional override for the underlying MCP Server (tests). */ /** Optional override for the underlying MCP Server (tests). */
server?: Server; server?: Server;
} }
@@ -54,8 +60,10 @@ export async function buildGateway(opts: GatewayOptions = {}): Promise<GatewayHa
upstreams.set( upstreams.set(
a.name, a.name,
new UpstreamAgent({ new UpstreamAgent({
name: a.name, url: a.url, token, name: a.name, url: a.url, mcpPath: a.mcpPath, token,
cpJwt, cpUrl, bucket, cpJwt, cpUrl, bucket,
requestTimeoutMs: opts.upstreamRequestTimeoutMs,
streamIdleTimeoutMs: opts.upstreamStreamIdleTimeoutMs,
}), }),
); );
} }
@@ -95,7 +103,7 @@ export async function buildGateway(opts: GatewayOptions = {}): Promise<GatewayHa
return { tools }; return { tools };
}); });
server.setRequestHandler(CallToolRequestSchema, async (req) => { server.setRequestHandler(CallToolRequestSchema, async (req, extra) => {
const fullName = req.params.name; const fullName = req.params.name;
const idx = fullName.indexOf(SEP); const idx = fullName.indexOf(SEP);
if (idx < 0) { if (idx < 0) {
@@ -107,10 +115,42 @@ export async function buildGateway(opts: GatewayOptions = {}): Promise<GatewayHa
if (!upstream) { if (!upstream) {
return _softError(`unknown agent: ${agentName}`) as any; return _softError(`unknown agent: ${agentName}`) as any;
} }
// Honor the client's progressToken if it supplied one; else fall
// back to the request id. Either way, when upstream emits
// notifications/progress we forward them via the SDK's
// sendNotification so clients like Claude Code reset their idle
// tool-call timer and don't abort long builds.
const clientToken = (req.params._meta as any)?.progressToken as
| string
| number
| undefined;
const progressToken = clientToken ?? (extra.requestId as string | number);
try { try {
const result = await upstream.callTool( const result = await upstream.callTool(
toolName, toolName,
(req.params.arguments as Record<string, unknown>) ?? {}, (req.params.arguments as Record<string, unknown>) ?? {},
{
progressToken,
onNotification: async (notif) => {
try {
await extra.sendNotification(notif as any);
} catch {
// best effort
}
},
onRequest: async (upstreamReq) => {
const schema = upstreamReq.method === "elicitation/create"
? ElicitResultSchema
: ResultSchema;
return extra.sendRequest(
{
method: upstreamReq.method,
params: upstreamReq.params,
} as any,
schema as any,
);
},
},
); );
// Pass through the upstream's CallToolResult as-is. Upstreams already // Pass through the upstream's CallToolResult as-is. Upstreams already
// populate content / structuredContent / isError per the MCP spec. // populate content / structuredContent / isError per the MCP spec.

View File

@@ -7,11 +7,16 @@
* header without coupling to a transport class. * header without coupling to a transport class.
*/ */
const JSON_RPC = "2.0"; const JSON_RPC = "2.0";
const DEFAULT_RPC_TIMEOUT_MS = 30_000;
const DEFAULT_STREAM_IDLE_TIMEOUT_MS = 120_000;
export interface UpstreamConfig { export interface UpstreamConfig {
name: string; name: string;
url: string; url: string;
mcpPath?: string;
token: string | null; token: string | null;
requestTimeoutMs?: number;
streamIdleTimeoutMs?: number;
/** Forwarded to the upstream as ``params._meta.cp_jwt`` on tools/call. /** Forwarded to the upstream as ``params._meta.cp_jwt`` on tools/call.
* Lets the upstream agent act on the caller's behalf (file/agent CRUD * Lets the upstream agent act on the caller's behalf (file/agent CRUD
* on /v1/me/*) — same path the platform orchestrator uses. */ * on /v1/me/*) — same path the platform orchestrator uses. */
@@ -39,6 +44,12 @@ export interface UpstreamCallResult {
isError?: boolean; isError?: boolean;
} }
export interface UpstreamServerRequest {
id: string | number;
method: string;
params?: Record<string, unknown>;
}
export class UpstreamError extends Error { export class UpstreamError extends Error {
constructor( constructor(
public agent: string, public agent: string,
@@ -52,43 +63,76 @@ export class UpstreamError extends Error {
let _nextId = 1; let _nextId = 1;
function normalizeMcpPath(path: string | undefined): string {
if (!path) return "/mcp";
const trimmed = path.trim();
if (!trimmed) return "/mcp";
return trimmed.startsWith("/") ? trimmed : `/${trimmed}`;
}
export class UpstreamAgent { export class UpstreamAgent {
constructor(private cfg: UpstreamConfig) { constructor(private cfg: UpstreamConfig) {
this.cfg.url = cfg.url.replace(/\/+$/, ""); this.cfg.url = cfg.url.replace(/\/+$/, "");
this.cfg.mcpPath = normalizeMcpPath(cfg.mcpPath);
} }
get name(): string { get name(): string {
return this.cfg.name; return this.cfg.name;
} }
private mcpUrl(): string {
return `${this.cfg.url}${this.cfg.mcpPath ?? "/mcp"}`;
}
private async rpc<T>(method: string, params: unknown): Promise<T> { private async rpc<T>(method: string, params: unknown): Promise<T> {
const id = _nextId++; const id = _nextId++;
const timeoutMs = this.cfg.requestTimeoutMs ?? DEFAULT_RPC_TIMEOUT_MS;
const controller = new AbortController();
let timedOut = false;
const timeout = setTimeout(() => {
timedOut = true;
controller.abort();
}, timeoutMs);
const headers: Record<string, string> = { const headers: Record<string, string> = {
"content-type": "application/json", "content-type": "application/json",
accept: "application/json", accept: "application/json",
}; };
if (this.cfg.token) headers["authorization"] = `Bearer ${this.cfg.token}`; if (this.cfg.token) headers["authorization"] = `Bearer ${this.cfg.token}`;
const resp = await fetch(`${this.cfg.url}/mcp`, { try {
method: "POST", const resp = await fetch(this.mcpUrl(), {
headers, method: "POST",
body: JSON.stringify({ jsonrpc: JSON_RPC, id, method, params }), headers,
}); body: JSON.stringify({ jsonrpc: JSON_RPC, id, method, params }),
signal: controller.signal,
});
if (!resp.ok) { if (!resp.ok) {
const text = await resp.text().catch(() => ""); const text = await resp.text().catch(() => "");
throw new UpstreamError(this.cfg.name, resp.status, text || resp.statusText); throw new UpstreamError(this.cfg.name, resp.status, text || resp.statusText);
} }
const env: any = await resp.json(); const env: any = await resp.json();
if (env?.error) { if (env?.error) {
throw new UpstreamError( throw new UpstreamError(
this.cfg.name, this.cfg.name,
500, 500,
`${env.error.code}: ${env.error.message}`, `${env.error.code}: ${env.error.message}`,
); );
}
return env?.result as T;
} catch (err) {
if (timedOut) {
throw new UpstreamError(
this.cfg.name,
504,
`request timed out after ${timeoutMs}ms`,
);
}
throw err;
} finally {
clearTimeout(timeout);
} }
return env?.result as T;
} }
async listTools(): Promise<UpstreamTool[]> { async listTools(): Promise<UpstreamTool[]> {
@@ -99,13 +143,244 @@ export class UpstreamAgent {
async callTool( async callTool(
name: string, name: string,
arguments_: Record<string, unknown>, arguments_: Record<string, unknown>,
opts: {
onNotification?: (notif: {
method: string;
params?: Record<string, unknown>;
}) => void | Promise<void>;
onRequest?: (req: UpstreamServerRequest) => unknown | Promise<unknown>;
progressToken?: string | number;
} = {},
): Promise<UpstreamCallResult> { ): Promise<UpstreamCallResult> {
const meta: Record<string, unknown> = {}; const meta: Record<string, unknown> = {};
if (this.cfg.cpJwt) meta.cp_jwt = this.cfg.cpJwt; if (this.cfg.cpJwt) meta.cp_jwt = this.cfg.cpJwt;
if (this.cfg.cpUrl) meta.cp_url = this.cfg.cpUrl; if (this.cfg.cpUrl) meta.cp_url = this.cfg.cpUrl;
if (this.cfg.bucket) meta.bucket = this.cfg.bucket; if (this.cfg.bucket) meta.bucket = this.cfg.bucket;
if (opts.progressToken !== undefined) meta.progressToken = opts.progressToken;
const params: Record<string, unknown> = { name, arguments: arguments_ }; const params: Record<string, unknown> = { name, arguments: arguments_ };
if (Object.keys(meta).length > 0) params._meta = meta; if (Object.keys(meta).length > 0) params._meta = meta;
return this.rpc<UpstreamCallResult>("tools/call", params); return this.streamingCallTool(params, {
onNotification: opts.onNotification,
onRequest: opts.onRequest,
});
}
/**
* tools/call always negotiates SSE on the wire — upstream agents can
* take minutes (agent-builder.build runs an LLM loop + sandbox tests +
* a deploy + a wait-for-live-card poll), and a plain JSON POST gets
* killed by ingress idle timeouts (~60s default on traefik). The
* upstream's SSE response interleaves any elicitation/create requests
* and a final tools/call result; here we relay server-to-client
* requests through the MCP client and return the final result.
*/
private async streamingCallTool(
params: Record<string, unknown>,
handlers: {
onNotification?: (notif: {
method: string;
params?: Record<string, unknown>;
}) => void | Promise<void>;
onRequest?: (req: UpstreamServerRequest) => unknown | Promise<unknown>;
} = {},
): Promise<UpstreamCallResult> {
const id = _nextId++;
const idleTimeoutMs =
this.cfg.streamIdleTimeoutMs ?? DEFAULT_STREAM_IDLE_TIMEOUT_MS;
const controller = new AbortController();
let timedOut = false;
let idleTimer: ReturnType<typeof setTimeout> | undefined;
const resetIdleTimer = () => {
if (idleTimer) clearTimeout(idleTimer);
idleTimer = setTimeout(() => {
timedOut = true;
controller.abort();
}, idleTimeoutMs);
};
resetIdleTimer();
const headers: Record<string, string> = {
"content-type": "application/json",
accept: "text/event-stream, application/json",
};
if (this.cfg.token) headers["authorization"] = `Bearer ${this.cfg.token}`;
let resp: Response;
try {
resp = await fetch(this.mcpUrl(), {
method: "POST",
headers,
body: JSON.stringify({
jsonrpc: JSON_RPC, id, method: "tools/call", params,
}),
signal: controller.signal,
});
} catch (err) {
clearTimeout(idleTimer);
if (timedOut) {
throw new UpstreamError(
this.cfg.name,
504,
`stream idle timeout after ${idleTimeoutMs}ms`,
);
}
throw err;
}
resetIdleTimer();
if (!resp.ok) {
const text = await resp.text().catch(() => "");
clearTimeout(idleTimer);
throw new UpstreamError(this.cfg.name, resp.status, text || resp.statusText);
}
const ctype = resp.headers.get("content-type") || "";
if (!ctype.includes("text/event-stream")) {
// Server fell back to JSON (older a2a-pack or non-SSE upstream).
const env: any = await resp.json();
if (env?.error) {
clearTimeout(idleTimer);
throw new UpstreamError(
this.cfg.name, 500,
`${env.error.code}: ${env.error.message}`,
);
}
clearTimeout(idleTimer);
return env?.result as UpstreamCallResult;
}
const upstreamSessionId = resp.headers.get("mcp-session-id");
if (!resp.body) {
clearTimeout(idleTimer);
throw new UpstreamError(this.cfg.name, 502, "empty stream body");
}
const reader = resp.body.getReader();
const decoder = new TextDecoder();
let buf = "";
try {
while (true) {
let done: boolean;
let value: Uint8Array | undefined;
try {
({ done, value } = await reader.read());
} catch (err) {
if (timedOut) {
throw new UpstreamError(
this.cfg.name,
504,
`stream idle timeout after ${idleTimeoutMs}ms`,
);
}
throw err;
}
if (value) {
resetIdleTimer();
buf += decoder.decode(value, { stream: true });
}
let sep = buf.indexOf("\n\n");
while (sep !== -1) {
const frame = buf.slice(0, sep);
buf = buf.slice(sep + 2);
const dataLines: string[] = [];
for (const ln of frame.split("\n")) {
if (ln.startsWith("data:")) dataLines.push(ln.slice(5).trimStart());
}
if (dataLines.length > 0) {
const raw = dataLines.join("\n");
if (raw === "[DONE]") {
sep = buf.indexOf("\n\n");
continue;
}
let msg: any;
try { msg = JSON.parse(raw); } catch { msg = null; }
if (msg && msg.id === id) {
if (msg.error) {
throw new UpstreamError(
this.cfg.name, 500,
`${msg.error.code}: ${msg.error.message}`,
);
}
return msg.result as UpstreamCallResult;
}
// Otherwise it's a server→client message. Notifications
// (no id) are best-effort. Requests (has id, has method), such
// as elicitation/create, must be relayed and answered upstream.
if (msg && typeof msg.method === "string" && !("id" in msg) && handlers.onNotification) {
try {
await handlers.onNotification({
method: msg.method,
params: msg.params as Record<string, unknown> | undefined,
});
} catch {
// Best-effort; never break the stream on a notify error.
}
} else if (msg && typeof msg.method === "string" && "id" in msg) {
await this.relayServerRequest(upstreamSessionId, {
id: msg.id as string | number,
method: msg.method,
params: msg.params as Record<string, unknown> | undefined,
}, handlers.onRequest);
resetIdleTimer();
}
}
sep = buf.indexOf("\n\n");
}
if (done) break;
}
} finally {
clearTimeout(idleTimer);
try { reader.releaseLock(); } catch { /* ignore */ }
}
throw new UpstreamError(this.cfg.name, 502, "stream ended without result");
}
private async relayServerRequest(
upstreamSessionId: string | null,
req: UpstreamServerRequest,
onRequest?: (req: UpstreamServerRequest) => unknown | Promise<unknown>,
): Promise<void> {
if (!upstreamSessionId) {
throw new UpstreamError(
this.cfg.name,
502,
`upstream request ${req.method} missing Mcp-Session-Id`,
);
}
let envelope: Record<string, unknown>;
try {
if (!onRequest) throw new Error(`no client request relay for ${req.method}`);
const result = await onRequest(req);
envelope = { jsonrpc: JSON_RPC, id: req.id, result };
} catch (err) {
envelope = {
jsonrpc: JSON_RPC,
id: req.id,
error: {
code: -32603,
message: err instanceof Error ? err.message : String(err),
},
};
}
const headers: Record<string, string> = {
"content-type": "application/json",
accept: "application/json",
"mcp-session-id": upstreamSessionId,
};
if (this.cfg.token) headers.authorization = `Bearer ${this.cfg.token}`;
const resp = await fetch(this.mcpUrl(), {
method: "POST",
headers,
body: JSON.stringify(envelope),
});
if (!resp.ok) {
const text = await resp.text().catch(() => "");
throw new UpstreamError(
this.cfg.name,
resp.status,
text || `failed to deliver response for ${req.method}`,
);
}
} }
} }

View File

@@ -9,7 +9,7 @@ import {
ListToolsRequestSchema, ListToolsRequestSchema,
} from "@modelcontextprotocol/sdk/types.js"; } from "@modelcontextprotocol/sdk/types.js";
import { buildGateway, SEP } from "../src/gateway.js"; import { buildGateway, SEP, type GatewayOptions } from "../src/gateway.js";
import type { EnabledAgent } from "../src/config.js"; import type { EnabledAgent } from "../src/config.js";
/** /**
@@ -70,25 +70,65 @@ function startFakeAgent(opts: {
}); });
} }
function startSseAgent(opts: {
onCall: (body: any, res: http.ServerResponse) => void;
}): Promise<{ url: string; close: () => Promise<void>; requests: any[] }> {
const requests: any[] = [];
return new Promise((resolve) => {
const server = http.createServer((req, res) => {
if (req.method !== "POST" || req.url !== "/mcp") {
res.statusCode = 404;
res.end();
return;
}
const chunks: Buffer[] = [];
req.on("data", (c) => chunks.push(c));
req.on("end", () => {
const body = JSON.parse(Buffer.concat(chunks).toString("utf8"));
requests.push({ body });
if (body.method !== "tools/call") {
res.setHeader("content-type", "application/json");
res.end(JSON.stringify({ jsonrpc: "2.0", id: body.id, result: {} }));
return;
}
res.writeHead(200, { "content-type": "text/event-stream" });
opts.onCall(body, res);
});
});
server.listen(0, "127.0.0.1", () => {
const { port } = server.address() as AddressInfo;
resolve({
url: `http://127.0.0.1:${port}`,
requests,
close: () => new Promise((r) => server.close(() => r())),
});
});
});
}
/** Drive an in-process gateway Server via the SDK's request handlers. */ /** Drive an in-process gateway Server via the SDK's request handlers. */
async function callGateway( async function callGateway(
agents: EnabledAgent[], agents: EnabledAgent[],
token: string | null, token: string | null,
method: "tools/list" | "tools/call", method: "tools/list" | "tools/call",
params: any, params: any,
opts: {
gateway?: Partial<Omit<GatewayOptions, "agents" | "token" | "server">>;
extra?: any;
} = {},
) { ) {
const mcpServer = new Server( const mcpServer = new Server(
{ name: "test", version: "0.0.0" }, { name: "test", version: "0.0.0" },
{ capabilities: { tools: { listChanged: false } } }, { capabilities: { tools: { listChanged: false } } },
); );
await buildGateway({ agents, token, server: mcpServer }); await buildGateway({ agents, token, server: mcpServer, ...opts.gateway });
// Reach into the server's registered handlers — the SDK exposes them via // Reach into the server's registered handlers — the SDK exposes them via
// a private map, so we route through the public schema-keyed lookup we // a private map, so we route through the public schema-keyed lookup we
// know is wired up. // know is wired up.
const schema = method === "tools/list" ? ListToolsRequestSchema : CallToolRequestSchema; const schema = method === "tools/list" ? ListToolsRequestSchema : CallToolRequestSchema;
const handler = (mcpServer as any)._requestHandlers.get(schema.shape.method.value); const handler = (mcpServer as any)._requestHandlers.get(schema.shape.method.value);
if (!handler) throw new Error("handler not registered"); if (!handler) throw new Error("handler not registered");
return handler({ method, params }, {} as any); return handler({ method, params }, opts.extra ?? ({} as any));
} }
test("tools/list aggregates upstream tools with agent prefix", async () => { test("tools/list aggregates upstream tools with agent prefix", async () => {
@@ -209,3 +249,168 @@ test("tools/call surfaces upstream JSON-RPC error as soft error", async () => {
await upstream.close(); await upstream.close();
} }
}); });
test("tools/call forwards upstream SSE progress notifications", async () => {
const upstream = await startSseAgent({
onCall: (body, res) => {
res.write(
`data: ${JSON.stringify({
jsonrpc: "2.0",
method: "notifications/progress",
params: { progressToken: "p1", message: "halfway" },
})}\n\n`,
);
res.end(
`data: ${JSON.stringify({
jsonrpc: "2.0",
id: body.id,
result: {
content: [{ type: "text", text: "done" }],
isError: false,
},
})}\n\n`,
);
},
});
const notifications: any[] = [];
try {
const result = await callGateway(
[{ name: "streamer", url: upstream.url, addedAt: "now" }],
null,
"tools/call",
{ name: `streamer${SEP}build`, arguments: {} },
{
extra: {
requestId: "req-1",
sendNotification: async (notification: any) => {
notifications.push(notification);
},
},
},
);
assert.equal(result.isError, false);
assert.deepEqual(notifications, [
{
method: "notifications/progress",
params: { progressToken: "p1", message: "halfway" },
},
]);
} finally {
await upstream.close();
}
});
test("tools/call reports upstream SSE idle timeout", async () => {
const upstream = await startSseAgent({
onCall: (_body, res) => {
res.write(": connected\n\n");
},
});
try {
const result = await callGateway(
[{ name: "slow", url: upstream.url, addedAt: "now" }],
null,
"tools/call",
{ name: `slow${SEP}build`, arguments: {} },
{ gateway: { upstreamStreamIdleTimeoutMs: 25 } },
);
assert.equal(result.isError, true);
assert.match(result.content[0].text, /stream idle timeout/);
} finally {
await upstream.close();
}
});
test("tools/call relays upstream elicitation requests", async () => {
let resolveResponse: (() => void) | undefined;
const responseSeen = new Promise<void>((resolve) => { resolveResponse = resolve; });
let upstreamResponse: any = null;
const requests: any[] = [];
const server = http.createServer((req, res) => {
if (req.method !== "POST" || req.url !== "/mcp") {
res.statusCode = 404;
res.end();
return;
}
const chunks: Buffer[] = [];
req.on("data", (c) => chunks.push(c));
req.on("end", () => {
const body = JSON.parse(Buffer.concat(chunks).toString("utf8"));
requests.push({ headers: req.headers, body });
if (body.method === "tools/call") {
res.writeHead(200, {
"content-type": "text/event-stream",
"Mcp-Session-Id": "sess-1",
});
res.write(
`data: ${JSON.stringify({
jsonrpc: "2.0",
id: "ask-1",
method: "elicitation/create",
params: { message: "Name?", requestedSchema: { type: "object" } },
})}\n\n`,
);
void responseSeen.then(() => {
res.end(
`data: ${JSON.stringify({
jsonrpc: "2.0",
id: body.id,
result: {
content: [{ type: "text", text: upstreamResponse.result.content.answer }],
isError: false,
},
})}\n\n`,
);
});
return;
}
if (body.id === "ask-1" && req.headers["mcp-session-id"] === "sess-1") {
upstreamResponse = body;
res.statusCode = 202;
res.end();
resolveResponse?.();
return;
}
res.setHeader("content-type", "application/json");
res.end(JSON.stringify({ jsonrpc: "2.0", id: body.id, result: {} }));
});
});
const upstream = await new Promise<{ url: string; close: () => Promise<void> }>((resolve) => {
server.listen(0, "127.0.0.1", () => {
const { port } = server.address() as AddressInfo;
resolve({
url: `http://127.0.0.1:${port}`,
close: () => new Promise((r) => server.close(() => r())),
});
});
});
const clientRequests: any[] = [];
try {
const result = await callGateway(
[{ name: "human", url: upstream.url, addedAt: "now" }],
null,
"tools/call",
{ name: `human${SEP}run_demo`, arguments: {} },
{
extra: {
requestId: "req-elicitation",
sendNotification: async () => {},
sendRequest: async (request: any) => {
clientRequests.push(request);
return { action: "accept", content: { answer: "Alice" } };
},
},
},
);
assert.equal(result.isError, false);
assert.equal(result.content[0].text, "Alice");
assert.equal(clientRequests[0].method, "elicitation/create");
assert.deepEqual(upstreamResponse.result, {
action: "accept",
content: { answer: "Alice" },
});
assert.ok(requests.some((r) => r.body.id === "ask-1"));
} finally {
await upstream.close();
}
});