77 lines
2.3 KiB
TypeScript
77 lines
2.3 KiB
TypeScript
const ACCEPT = "application/json, text/event-stream";
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interface JsonRpcResponse {
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result?: unknown;
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error?: { code: number; message: string };
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}
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interface McpTool {
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name: string;
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description?: string;
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inputSchema?: unknown;
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}
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type McpContentBlock = { type: string; text: string } | { type: string; [key: string]: unknown };
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interface McpToolResult {
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content?: McpContentBlock[];
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}
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function parseMcpResponse(text: string): JsonRpcResponse {
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const trimmed = text.trim();
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if (!trimmed) throw new Error("Empty MCP response");
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if (trimmed.startsWith("{")) {
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return JSON.parse(trimmed) as JsonRpcResponse;
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}
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if (trimmed.includes("event:") || trimmed.includes("data:")) {
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let payload = "";
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for (const line of trimmed.split(/\r?\n/)) {
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if (line.startsWith("data:")) payload += line.slice(5).trim();
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}
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if (payload.startsWith("{")) return JSON.parse(payload) as JsonRpcResponse;
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}
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throw new Error(`Unrecognized MCP response format: ${trimmed.slice(0, 200)}`);
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}
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export class McpClient {
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private url: string;
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private seq: number;
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constructor(url: string) {
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this.url = url;
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this.seq = 0;
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}
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async request(method: string, params: Record<string, unknown> = {}): Promise<JsonRpcResponse> {
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this.seq += 1;
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const res = await fetch(this.url, {
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method: "POST",
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headers: { "Content-Type": "application/json", Accept: ACCEPT },
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body: JSON.stringify({ jsonrpc: "2.0", id: this.seq, method, params }),
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});
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if (!res.ok) {
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throw new Error(`MCP HTTP ${res.status}: ${(await res.text()).slice(0, 300)}`);
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}
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const rpc = parseMcpResponse(await res.text());
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if (rpc.error) throw new Error(`MCP RPC error ${rpc.error.code}: ${rpc.error.message}`);
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return rpc;
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}
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async listTools(): Promise<McpTool[]> {
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const rpc = await this.request("tools/list");
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return (rpc.result as { tools?: McpTool[] })?.tools ?? [];
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}
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async callTool(name: string, args: Record<string, unknown> = {}): Promise<McpToolResult> {
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const rpc = await this.request("tools/call", { name, arguments: args });
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return rpc.result as McpToolResult;
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}
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}
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export function textContentFrom(result: McpToolResult | null | undefined): string {
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if (!result?.content) return "";
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return result.content
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.map((b) => (b.type === "text" ? b.text : JSON.stringify(b)))
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.join(" ");
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}
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