fix(cursor): keep ambient MCP when sending t3-code servers

apps/server/package.json

@@ -34,7 +34,7 @@
   },
   "dependencies": {
     "@anthropic-ai/claude-agent-sdk": "^0.3.276",
-    "@cursor/sdk": "1.0.38",
+    "@cursor/sdk": "1.2.0",
     "@effect/platform-node": "catalog:",
     "@effect/platform-node-shared": "catalog:",
     "@ff-labs/fff-node": "0.11.0",

docs/orchestration-v2/orchestrator-mcp-server.md

@@ -98,8 +98,11 @@ server headers or token.
 ### Cursor Agent SDK V2
 
 Cursor receives the same authenticated HTTP MCP endpoint through the SDK's
-`mcpServers` agent and send options. The adapter passes the authorization header
-to the SDK but projects only redacted option metadata into protocol diagnostics.
+`mcpServers` on `Agent.create` / `Agent.resume` and each `send`. With
+`@cursor/sdk` 1.0.39+, send-level servers replace only the create-time inline
+set; ambient servers from `settingSources` (`project`, `user`, `team`, `mdm`,
+`plugins`) stay available. The adapter passes the authorization header to the
+SDK but projects only redacted option metadata into protocol diagnostics.
 
 ### Grok ACP V2
 

docs/user/cursor.md

@@ -15,6 +15,17 @@ The adapter currently uses the SDK's local-agent runtime so runs operate in the
 workspace. Cursor cloud agents need repository and cloud-environment configuration that T3 Code does
 not expose yet.
 
+Custom Cursor MCP servers and plugins are not configured in T3 Code. They load from the environment
+machine's Cursor config when the agent opens: project `.cursor/mcp.json`, user `~/.cursor/mcp.json`,
+and installed plugins under `~/.cursor/plugins`. Plugin tools
+can appear without a login; OAuth MCP servers still need credentials. Run `agent mcp login <server>`
+with the cwd set to the T3 project root (tokens land in
+`~/.cursor/projects/<folder-slug>/mcp-auth.json`). Cursor desktop Connections auth does not write
+that file, and the local SDK cannot complete interactive MCP OAuth itself—auth attempts fail with
+messages such as "MCP authentication is not supported in local SDK runs" or that the auth server
+does not support dynamic client registration. After you add or change skills, plugins, or MCP
+servers, or after a successful CLI login, use **Restart agent session**.
+
 ## Sign in
 
 Choose **Sign in**, then open the sign-in page and complete it in your browser. T3 Code
@@ -36,7 +47,7 @@ The adapter supports:
 - creating and resuming local Cursor agent threads;
 - changing the model and model parameters between turns;
 - assistant text, reasoning, tool activity, plans, and todo streaming;
-- thread-scoped T3 Code MCP tools;
+- thread-scoped T3 Code MCP tools alongside ambient Cursor MCP/plugins from disk;
 - image attachments;
 - interruption, queued app messages, and orchestrator-owned interrupt/restart steering;
 - provider conversation snapshots through `Agent.messages.list()`;

packages/provider-cursor/package.json

@@ -49,7 +49,7 @@
     "test": "vp test run --config ../../vite.config.ts --dir ."
   },
   "dependencies": {
-    "@cursor/sdk": "1.0.38",
+    "@cursor/sdk": "1.2.0",
     "@napi-rs/keyring": "^1.3.0",
     "@t3tools/contracts": "workspace:*",
     "@t3tools/provider-core": "workspace:*",

packages/provider-cursor/src/server/CursorAgentSdk.ts

@@ -139,6 +139,8 @@ export interface CursorAgentSdkLoggedAgentOptions {
 export interface CursorAgentSdkLoggedSendOptions {
   readonly model?: SendOptions["model"];
   readonly mode?: SendOptions["mode"];
+  readonly hasMcpServers?: boolean;
+  readonly mcpServerNames?: ReadonlyArray<string>;
   readonly local?: {
     readonly force?: boolean;
     readonly hasCustomTools?: boolean;
@@ -298,9 +300,12 @@ export function loggedCursorSendOptions(
   if (options === undefined) {
     return {};
   }
+  const mcpServerNames =
+    options.mcpServers === undefined ? undefined : Object.keys(options.mcpServers).toSorted();
   return {
     ...(options.model === undefined ? {} : { model: options.model }),
     ...(options.mode === undefined ? {} : { mode: options.mode }),
+    ...(mcpServerNames === undefined ? {} : { hasMcpServers: true, mcpServerNames }),
     ...(options.local === undefined
       ? {}
       : {

packages/provider-cursor/src/server/adapter.test.ts

@@ -217,7 +217,7 @@ describe("CursorAdapterV2", () => {
           Stream.takeUntil((event) => event.type === "turn.terminal"),
           Stream.runCollect,
         );
-        assert.isFalse(sentWithMcpOverride);
+        assert.isTrue(sentWithMcpOverride);
         const rows = events.filter((event) => event.type === "subagent.updated");
         assert.equal(rows[0]?.subagent.status, "running");
         assert.equal(rows[0]?.subagent.model, model ?? null);

packages/provider-cursor/src/server/adapter.ts

@@ -2387,13 +2387,14 @@ export const makeCursorAdapterV2 = Effect.fn("makeCursorAdapterV2")(function* (
             );
             const pendingUpdates: Array<InteractionUpdate> = [];
             let context: ActiveCursorTurn | null = null;
-            // MCP send overrides replace the ambient servers loaded when the agent opens.
+            // Create-time and send-time mcpServers merge with settingSources (SDK >= 1.0.39).
             const sdkRun = yield* agent.session
               .send({
                 message,
                 options: {
                   model: cursorSdkModelSelection(turnInput.modelSelection),
                   mode: turnInput.runtimePolicy.interactionMode === "plan" ? "plan" : "agent",
+                  ...(mcpServers === undefined ? {} : { mcpServers }),
                 },
                 onDelta: (update) => {
                   if (context === null) {

pnpm-workspace.yaml

@@ -227,6 +227,12 @@ minimumReleaseAgeExclude:
   - "@pierre/highlights@0.2.0"
   - "@pierre/theming@1.0.2"
   - agent-device@0.21.32
+  - "@cursor/sdk-darwin-arm64@1.2.0"
+  - "@cursor/sdk-darwin-x64@1.2.0"
+  - "@cursor/sdk-linux-arm64@1.2.0"
+  - "@cursor/sdk-linux-x64@1.2.0"
+  - "@cursor/sdk-win32-x64@1.2.0"
+  - "@cursor/sdk@1.2.0"
 
 overrides:
   # Pin every patched package, including transitive dependencies, so lockfile-free