feat(mcp): support client roots (#32230)

packages/opencode/src/mcp/index.ts

@@ -1,4 +1,5 @@
 import path from "node:path"
+import { pathToFileURL } from "node:url"
 import { LayerNode } from "@opencode-ai/core/effect/layer-node"
 import { type Tool } from "ai"
 import { ConfigV1 } from "@opencode-ai/core/v1/config/config"
@@ -9,6 +10,7 @@ import { SSEClientTransport } from "@modelcontextprotocol/sdk/client/sse.js"
 import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js"
 import { UnauthorizedError } from "@modelcontextprotocol/sdk/client/auth.js"
 import {
+  ListRootsRequestSchema,
   type LoggingMessageNotification,
   LoggingMessageNotificationSchema,
   type Tool as MCPToolDef,
@@ -42,7 +44,7 @@ const CLIENT_OPTIONS = {
     // https://github.com/anomalyco/opencode/issues/23066
     // elicitation: {},
     // https://github.com/anomalyco/opencode/issues/2308
-    // roots: {},
+    roots: {},
     // https://github.com/anomalyco/opencode/issues/28567
     // tasks: {},
   },
@@ -82,6 +84,14 @@ export class NotFoundError extends Schema.TaggedErrorClass<NotFoundError>()("MCP
 
 type MCPClient = Client
 
+function createClient(directory: string) {
+  const client = new Client({ name: "opencode", version: InstallationVersion }, CLIENT_OPTIONS)
+  client.setRequestHandler(ListRootsRequestSchema, () =>
+    Promise.resolve({ roots: [{ uri: pathToFileURL(directory).href }] }),
+  )
+  return client
+}
+
 const StatusConnected = Schema.Struct({ status: Schema.Literal("connected") }).annotate({
   identifier: "MCPStatusConnected",
 })
@@ -192,19 +202,21 @@ export const layer = Layer.effect(
      * Connect a client via the given transport with resource safety:
      * on failure the transport is closed; on success the caller owns it.
      */
-    const connectTransport = (transport: Transport, timeout: number) =>
+    const connectTransport = Effect.fn("MCP.connectTransport")(function* (transport: Transport, timeout: number) {
-      Effect.acquireUseRelease(
+      const directory = yield* InstanceState.directory
+      return yield* Effect.acquireUseRelease(
         Effect.succeed(transport),
         (t) =>
           Effect.tryPromise({
             try: () => {
-              const client = new Client({ name: "opencode", version: InstallationVersion }, CLIENT_OPTIONS)
+              const client = createClient(directory)
               return withTimeout(client.connect(t), timeout).then(() => client)
             },
             catch: (e) => (e instanceof Error ? e : new Error(String(e))),
           }),
         (t, exit) => (Exit.isFailure(exit) ? Effect.tryPromise(() => t.close()).pipe(Effect.ignore) : Effect.void),
       )
+    })
 
     const DISABLED_RESULT: CreateResult = { status: { status: "disabled" } }
 
@@ -777,10 +789,11 @@ export const layer = Layer.effect(
         authProvider,
         requestInit: mcpConfig.headers ? { headers: mcpConfig.headers } : undefined,
       })
+      const directory = yield* InstanceState.directory
 
       return yield* Effect.tryPromise({
         try: () => {
-          const client = new Client({ name: "opencode", version: InstallationVersion }, CLIENT_OPTIONS)
+          const client = createClient(directory)
           return client
             .connect(transport)
             .then(() => ({ authorizationUrl: "", oauthState, client }) satisfies AuthResult)

packages/opencode/test/mcp/lifecycle.test.ts

@@ -1,6 +1,7 @@
 import path from "node:path"
+import { pathToFileURL } from "node:url"
 import { expect, mock, beforeEach } from "bun:test"
-import { ToolListChangedNotificationSchema } from "@modelcontextprotocol/sdk/types.js"
+import { ListRootsRequestSchema, ToolListChangedNotificationSchema } from "@modelcontextprotocol/sdk/types.js"
 import { Cause, Effect, Exit } from "effect"
 import type { MCP as MCPNS } from "../../src/mcp/index"
 import { testEffect } from "../lib/effect"
@@ -38,6 +39,8 @@ interface MockClientState {
     { resources: Array<{ name: string; uri: string; description?: string }>; nextCursor?: string }
   >
   closed: boolean
+  clientOptions?: { capabilities?: { roots?: { listChanged?: boolean } } }
+  requestHandlers: Map<unknown, (...args: any[]) => Promise<any>>
   notificationHandlers: Map<unknown, (...args: any[]) => any>
 }
 
@@ -75,6 +78,7 @@ function getOrCreateClientState(name?: string): MockClientState {
       promptPages: {},
       resourcePages: {},
       closed: false,
+      requestHandlers: new Map(),
       notificationHandlers: new Map(),
     }
     clientStates.set(key, state)
@@ -149,8 +153,10 @@ void mock.module("@modelcontextprotocol/sdk/client/index.js", () => ({
     _state!: MockClientState
     transport: any
 
-    constructor(_opts: any) {
+    constructor(_info: any, options?: MockClientState["clientOptions"]) {
       clientCreateCount++
+      this._state = getOrCreateClientState(lastCreatedClientName)
+      this._state.clientOptions = options
     }
 
     async connect(transport: { start: () => Promise<void> }) {
@@ -160,6 +166,10 @@ void mock.module("@modelcontextprotocol/sdk/client/index.js", () => ({
       this._state = getOrCreateClientState(lastCreatedClientName)
     }
 
+    setRequestHandler(schema: unknown, handler: (...args: any[]) => Promise<any>) {
+      this._state.requestHandlers.set(schema, handler)
+    }
+
     setNotificationHandler(schema: unknown, handler: (...args: any[]) => any) {
       this._state?.notificationHandlers.set(schema, handler)
     }
@@ -251,6 +261,28 @@ function statusName(status: Record<string, MCPNS.Status> | MCPNS.Status, server:
   return status[server]?.status
 }
 
+it.instance(
+  "advertises and lists the instance directory as its root",
+  () =>
+    MCP.Service.use((mcp: MCPNS.Interface) =>
+      Effect.gen(function* () {
+        const { directory } = yield* TestInstance
+        lastCreatedClientName = "roots"
+        yield* mcp.add("roots", { type: "local", command: ["echo", "test"] })
+
+        const state = getOrCreateClientState("roots")
+        expect(state.clientOptions?.capabilities?.roots).toEqual({})
+        expect(state.clientOptions?.capabilities?.roots?.listChanged).toBeUndefined()
+
+        const handler = state.requestHandlers.get(ListRootsRequestSchema)
+        expect(handler).toBeDefined()
+        const result = yield* Effect.promise(() => handler?.() ?? Promise.reject(new Error("roots handler missing")))
+        expect(result).toEqual({ roots: [{ uri: pathToFileURL(directory).href }] })
+      }),
+    ),
+  { config: { mcp: {} } },
+)
+
 it.instance(
   "local mcp cwd resolves relative paths against instance directory",
   () =>

packages/opencode/test/mcp/oauth-auto-connect.test.ts

@@ -87,6 +87,8 @@ void mock.module("@modelcontextprotocol/sdk/client/sse.js", () => ({
 // Mock the MCP SDK Client
 void mock.module("@modelcontextprotocol/sdk/client/index.js", () => ({
   Client: class MockClient {
+    setRequestHandler() {}
+
     async connect(transport: { start: () => Promise<void> }) {
       await transport.start()
     }

packages/opencode/test/mcp/oauth-browser.test.ts

@@ -89,6 +89,8 @@ void mock.module("@modelcontextprotocol/sdk/client/sse.js", () => ({
 // Mock the MCP SDK Client to trigger OAuth flow
 void mock.module("@modelcontextprotocol/sdk/client/index.js", () => ({
   Client: class MockClient {
+    setRequestHandler() {}
+
     async connect(transport: { start: () => Promise<void> }) {
       await transport.start()
     }