From 644b90d9751398d01ccf2b5c487db504ba616a24 Mon Sep 17 00:00:00 2001
From: Aiden Cline <aidenpcline@gmail.com>
Date: Mon, 29 Jun 2026 10:13:13 -0500
Subject: [PATCH] client.ts

---
 packages/core/src/mcp/client.ts | 82 +++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 packages/core/src/mcp/client.ts

diff --git a/packages/core/src/mcp/client.ts b/packages/core/src/mcp/client.ts
new file mode 100644
index 0000000000..0df53d160d
--- /dev/null
+++ b/packages/core/src/mcp/client.ts
@@ -0,0 +1,82 @@
+export * as MCPClient from "./client"
+
+import path from "node:path"
+import { pathToFileURL } from "node:url"
+import { Client, type ClientOptions } from "@modelcontextprotocol/sdk/client/index.js"
+import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js"
+import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js"
+import { UnauthorizedError } from "@modelcontextprotocol/sdk/client/auth.js"
+import { ListRootsRequestSchema } from "@modelcontextprotocol/sdk/types.js"
+import { Cause, Effect, Exit, Schema } from "effect"
+import { ConfigMCP } from "../config/mcp"
+import { InstallationVersion } from "../installation/version"
+
+const DEFAULT_STARTUP_TIMEOUT = 30_000
+
+export class NeedsAuthError extends Schema.TaggedErrorClass<NeedsAuthError>()("MCP.NeedsAuthError", {
+  server: Schema.String,
+}) {}
+
+export class ConnectError extends Schema.TaggedErrorClass<ConnectError>()("MCP.ConnectError", {
+  server: Schema.String,
+  message: Schema.String,
+}) {}
+
+/**
+ * Connects an MCP client and registers a scoped finalizer that closes it. The
+ * returned client is owned by the calling scope; closing that scope tears down
+ * the transport (and, for local servers, the spawned process).
+ */
+export const connect = Effect.fnUntraced(function* (
+  server: string,
+  config: typeof ConfigMCP.Server.Type,
+  directory: string,
+) {
+  const transport = yield* Effect.gen(function* () {
+    if (config.type === "local") {
+      const [command, ...args] = config.command
+      return new StdioClientTransport({
+        command,
+        args,
+        cwd: config.cwd ? path.resolve(directory, config.cwd) : directory,
+        stderr: "pipe",
+        env: {
+          ...(process.env as Record<string, string>),
+          ...(command === "opencode" ? { BUN_BE_BUN: "1" } : {}),
+          ...config.environment,
+        },
+      })
+    }
+    if (!URL.canParse(config.url)) return yield* new ConnectError({ server, message: `Invalid MCP URL for "${server}"` })
+    return new StreamableHTTPClientTransport(new URL(config.url), {
+      requestInit: config.headers ? { headers: config.headers } : undefined,
+    })
+  })
+  const client = new Client(
+    { name: "opencode", version: InstallationVersion },
+    {
+      capabilities: {
+        // https://github.com/anomalyco/opencode/issues/2308
+        roots: {},
+      },
+    },
+  )
+  client.setRequestHandler(ListRootsRequestSchema, () =>
+    Promise.resolve({ roots: [{ uri: pathToFileURL(directory).href }] }),
+  )
+
+  const exit = yield* Effect.tryPromise({
+    try: (signal) => client.connect(transport, { timeout: config.timeout?.startup ?? DEFAULT_STARTUP_TIMEOUT, signal }),
+    catch: (error) => error,
+  }).pipe(Effect.exit)
+  if (Exit.isSuccess(exit)) {
+    yield* Effect.addFinalizer(() => Effect.promise(() => client.close()).pipe(Effect.ignore))
+    return client
+  }
+
+  yield* Effect.promise(() => transport.close()).pipe(Effect.ignore)
+  const error = Cause.squash(exit.cause)
+  if (error instanceof UnauthorizedError || (error instanceof Error && error.message.includes("OAuth")))
+    return yield* new NeedsAuthError({ server })
+  return yield* new ConnectError({ server, message: error instanceof Error ? error.message : String(error) })
+})