fix(cursor): /compact compacts with the SDK's summarize

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

@@ -89,6 +89,8 @@ export interface CursorAgentSdkSendInput<Error> {
   readonly message: string | SDKUserMessage;
   readonly options?: Omit<SendOptions, "onDelta">;
   readonly onDelta?: (update: InteractionUpdate) => Effect.Effect<void, Error>;
+  /** Runs `agent.summarize()` instead, which takes no message or options. */
+  readonly summarize?: boolean;
 }
 
 export interface CursorAgentSdkRun {
@@ -139,6 +141,8 @@ 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 +302,12 @@ 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
       ? {}
       : {
@@ -460,16 +467,18 @@ export const makeCursorAgentSdkRunner = Effect.fn("makeCursorAgentSdkRunner")(fu
           const startRun = () =>
             Effect.tryPromise({
               try: () =>
-                agent.send(sendInput.message, {
-                  ...sendInput.options,
-                  onDelta: async ({ update }) => {
-                    if (!callbacksReady) {
-                      pendingUpdates.push(update);
-                      return;
-                    }
-                    await dispatchUpdate(update);
-                  },
-                }),
+                sendInput.summarize === true
+                  ? agent.summarize()
+                  : agent.send(sendInput.message, {
+                      ...sendInput.options,
+                      onDelta: async ({ update }) => {
+                        if (!callbacksReady) {
+                          pendingUpdates.push(update);
+                          return;
+                        }
+                        await dispatchUpdate(update);
+                      },
+                    }),
               catch: (cause) => runnerError(cause, "run.start"),
             });
           const run = yield* startRun().pipe(

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);
@@ -508,11 +508,11 @@ describe("CursorAdapterV2", () => {
     ),
   );
 
-  it.effect("fails standalone SDK transport diagnostics and sends compaction as /compress", () =>
+  it.effect("fails standalone SDK transport diagnostics and compacts with SDK summarize", () =>
     Effect.gen(function* () {
       const fileSystem = yield* FileSystem.FileSystem;
       const workspace = yield* fileSystem.makeTempDirectoryScoped({ prefix: "cursor-v2-errors-" });
-      const sentMessages: Array<string> = [];
+      const summarizeRequests: Array<boolean> = [];
       let sendCalls = 0;
       const instanceId = ProviderInstanceId.make("cursor");
       const threadId = ThreadId.make("cursor-transport-error-thread");
@@ -536,9 +536,7 @@ describe("CursorAdapterV2", () => {
               send: (input) =>
                 Effect.sync(() => {
                   sendCalls += 1;
-                  sentMessages.push(
-                    typeof input.message === "string" ? input.message : input.message.text,
-                  );
+                  summarizeRequests.push(input.summarize === true);
                   const runId = `native-cursor-run-${sendCalls}`;
                   return {
                     agentId: "native-cursor-error",
@@ -549,9 +547,10 @@ describe("CursorAdapterV2", () => {
                       status: "finished" as const,
                       model: { id: "composer-2.5" },
                       durationMs: 1,
-                      ...(sendCalls === 1
-                        ? { result: "Error: RetriableError: WritableIterable is closed" }
-                        : {}),
+                      result:
+                        sendCalls === 1
+                          ? "Error: RetriableError: WritableIterable is closed"
+                          : "Summary of the conversation so far",
                     }),
                     cancel: Effect.void,
                   };
@@ -644,11 +643,12 @@ describe("CursorAdapterV2", () => {
           attachments: [],
         },
       });
-      yield* runtime.events.pipe(
-        Stream.filter((event) => event.type === "turn.terminal"),
-        Stream.runHead,
+      const compactionEvents = yield* runtime.events.pipe(
+        Stream.takeUntil((event) => event.type === "turn.terminal"),
+        Stream.runCollect,
       );
-      assert.equal(sentMessages[1], "/compress");
+      assert.deepEqual(summarizeRequests, [false, true]);
+      assert.notInclude(JSON.stringify(compactionEvents), "Summary of the conversation so far");
     }).pipe(
       Effect.scoped,
       Effect.provide(

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

@@ -2385,15 +2385,18 @@ export const makeCursorAdapterV2 = Effect.fn("makeCursorAdapterV2")(function* (
               hasDeviceTools,
               delivered,
             );
+            const compacted = message === "/compress";
             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,
+                summarize: compacted,
                 options: {
                   model: cursorSdkModelSelection(turnInput.modelSelection),
                   mode: turnInput.runtimePolicy.interactionMode === "plan" ? "plan" : "agent",
+                  ...(mcpServers === undefined ? {} : { mcpServers }),
                 },
                 onDelta: (update) => {
                   if (context === null) {
@@ -2405,7 +2408,6 @@ export const makeCursorAdapterV2 = Effect.fn("makeCursorAdapterV2")(function* (
                 },
               })
               .pipe(Effect.mapError(classifyCursorModelRejection(turnInput.modelSelection)));
-            const compacted = message === "/compress";
             yield* Ref.set(told, {
               agent: agent.nativeThreadId,
               orchestration: !compacted && (delivered.orchestration || mcpServers !== undefined),
@@ -2469,6 +2471,8 @@ export const makeCursorAdapterV2 = Effect.fn("makeCursorAdapterV2")(function* (
                   if (
                     context !== null &&
                     context.assistant.nextSegment === 0 &&
+                    // A summarize run's result is the summary, not an answer.
+                    !compacted &&
                     // Text from a resume that made no progress is not the turn's answer.
                     !isResumeFailureAfterTurnEnded(context, result) &&
                     result.result !== undefined &&

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