initial: @a2a/mcp gateway for a2acloud agents

Local MCP server that exposes any number of deployed A2A agents to
Claude Code, Cursor, Windsurf, and other MCP clients. Reuses the
~/.a2a/credentials.json token written by the Python a2a CLI. Adding
or removing agents is a single ~/.a2a/mcp.json edit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/api.ts

@@ -0,0 +1,81 @@
+/**
+ * Thin control-plane client. Mirrors the relevant subset of
+ * a2a_pack.cli.api_client.ControlPlaneClient.
+ */
+export class ApiError extends Error {
+  constructor(public status: number, message: string) {
+    super(`API ${status}: ${message}`);
+    this.name = "ApiError";
+  }
+}
+
+export interface AgentRow {
+  name: string;
+  version: string;
+  status: string;
+  url?: string;
+  description?: string;
+}
+
+export class ControlPlaneClient {
+  constructor(
+    private apiUrl: string,
+    private token: string | null,
+  ) {
+    this.apiUrl = apiUrl.replace(/\/+$/, "");
+  }
+
+  private headers(): Record<string, string> {
+    const h: Record<string, string> = { "content-type": "application/json" };
+    if (this.token) h["authorization"] = `bearer ${this.token}`;
+    return h;
+  }
+
+  private async request<T>(method: string, path: string, body?: unknown): Promise<T> {
+    const resp = await fetch(`${this.apiUrl}${path}`, {
+      method,
+      headers: this.headers(),
+      body: body !== undefined ? JSON.stringify(body) : undefined,
+    });
+    if (!resp.ok) {
+      let detail: string;
+      try {
+        const j: any = await resp.json();
+        detail = j?.detail ?? JSON.stringify(j);
+      } catch {
+        detail = await resp.text();
+      }
+      throw new ApiError(resp.status, detail);
+    }
+    if (resp.status === 204) return undefined as T;
+    return (await resp.json()) as T;
+  }
+
+  login(email: string, password: string) {
+    return this.request<{ access_token: string; user: { email: string } }>(
+      "POST",
+      "/v1/auth/login",
+      { email, password },
+    );
+  }
+
+  signup(email: string, password: string) {
+    return this.request<{ access_token: string; user: { email: string } }>(
+      "POST",
+      "/v1/auth/signup",
+      { email, password },
+    );
+  }
+
+  me() {
+    return this.request<{ email: string }>("GET", "/v1/me");
+  }
+
+  listAgents() {
+    return this.request<AgentRow[]>("GET", "/v1/agents");
+  }
+
+  getAgent(name: string) {
+    return this.request<AgentRow>("GET", `/v1/agents/${encodeURIComponent(name)}`);
+  }
+}