Choose non-fast variants for ACP models (#1952)

* fix(providers): expose ACP fast-mode selection

Provider wrappers now forward draft feature lookups to inner ACP clients, and ACP adapters can add initialize metadata for model parameterization. Fast-mode config options flow through the existing provider feature path.

* test(providers): cover wrapped ACP command lookup

* fix(providers): submit Cursor non-fast defaults

* fix(app): preserve parameterized model preferences

* fix(providers): preserve Cursor ACP feature params

* fix(providers): keep Cursor legacy model fallbacks

* fix(providers): preserve Cursor model parameter switches

* refactor(providers): simplify ACP model feature negotiation

packages/server/src/server/agent/provider-registry.test.ts

@@ -3,8 +3,10 @@ import { beforeEach, describe, expect, test, vi } from "vitest";
 import { createTestLogger } from "../../test-utils/test-logger.js";
 import type {
   AgentClient,
+  AgentFeature,
   AgentModelDefinition,
   AgentMode,
+  AgentSessionConfig,
   ProviderCatalog,
 } from "./agent-sdk-types.js";
 
@@ -41,6 +43,7 @@ const mockState = vi.hoisted(() => {
     },
     isCommandAvailable: vi.fn(async (_command: string) => false),
     runtimeModels: new Map<string, AgentModelDefinition[]>(),
+    cursorListFeaturesConfigs: [] as AgentSessionConfig[],
     reset() {
       this.constructorArgs.claude = [];
       this.constructorArgs.codex = [];
@@ -52,6 +55,7 @@ const mockState = vi.hoisted(() => {
       this.isCommandAvailable.mockReset();
       this.isCommandAvailable.mockImplementation(async (_command: string) => false);
       this.runtimeModels.clear();
+      this.cursorListFeaturesConfigs = [];
     },
   };
 });
@@ -378,6 +382,19 @@ vi.mock("./providers/cursor-acp-agent.js", () => ({
     async isAvailable(): Promise<boolean> {
       return true;
     }
+
+    async listFeatures(config: AgentSessionConfig): Promise<AgentFeature[]> {
+      mockState.cursorListFeaturesConfigs.push(config);
+      return [
+        {
+          type: "select",
+          id: "fast",
+          label: "Fast",
+          value: "false",
+          options: [{ id: "false", label: "Off" }],
+        },
+      ];
+    }
   },
 }));
 
@@ -697,6 +714,41 @@ test("cursor provider extending acp uses CursorACPAgentClient", () => {
   expect(mockState.constructorArgs.genericAcp).toEqual([]);
 });
 
+test("wrapped cursor client lists ACP features through the inner provider", async () => {
+  const registry = buildProviderRegistry(logger, {
+    providerOverrides: {
+      cursor: {
+        extends: "acp",
+        label: "Cursor",
+        command: ["cursor-agent", "acp"],
+      },
+    },
+  });
+
+  const client = registry.cursor.createClient(logger);
+
+  await expect(
+    client.listFeatures?.({
+      provider: "cursor",
+      cwd: "/tmp/cursor",
+    }),
+  ).resolves.toEqual([
+    {
+      type: "select",
+      id: "fast",
+      label: "Fast",
+      value: "false",
+      options: [{ id: "false", label: "Off" }],
+    },
+  ]);
+  expect(mockState.cursorListFeaturesConfigs).toEqual([
+    {
+      provider: "acp",
+      cwd: "/tmp/cursor",
+    },
+  ]);
+});
+
 test("traecli provider extending acp uses TraeACPAgentClient", () => {
   const registry = buildProviderRegistry(logger, {
     providerOverrides: {

packages/server/src/server/agent/provider-registry.ts

@@ -398,6 +398,7 @@ function wrapClientProvider(
 ): AgentClient {
   const listImportableSessions = inner.listImportableSessions?.bind(inner);
   const importSession = inner.importSession?.bind(inner);
+  const listFeatures = inner.listFeatures?.bind(inner);
 
   return {
     provider,
@@ -441,6 +442,9 @@ function wrapClientProvider(
     },
     resolveCreateConfig: inner.resolveCreateConfig?.bind(inner),
     isCreateConfigUnattended: inner.isCreateConfigUnattended?.bind(inner),
+    listFeatures: listFeatures
+      ? async (config) => await listFeatures({ ...config, provider: inner.provider })
+      : undefined,
     listImportableSessions: listImportableSessions
       ? async (options) => await listImportableSessions(options)
       : undefined,

packages/server/src/server/agent/providers/acp-agent.ts

@@ -229,7 +229,7 @@ export const DEFAULT_ACP_CAPABILITIES: AgentCapabilityFlags = {
   supportsRewindBoth: false,
 };
 
-const ACP_CLIENT_CAPABILITIES: ACPClientCapabilities = {
+const BASE_ACP_CLIENT_CAPABILITIES: ACPClientCapabilities = {
   fs: {
     readTextFile: true,
     writeTextFile: true,
@@ -237,6 +237,18 @@ const ACP_CLIENT_CAPABILITIES: ACPClientCapabilities = {
   terminal: true,
 };
 
+export type ACPClientCapabilityMeta = Record<string, unknown>;
+
+export function buildACPClientCapabilities(meta?: ACPClientCapabilityMeta): ACPClientCapabilities {
+  if (!meta || Object.keys(meta).length === 0) {
+    return BASE_ACP_CLIENT_CAPABILITIES;
+  }
+  return {
+    ...BASE_ACP_CLIENT_CAPABILITIES,
+    _meta: meta,
+  };
+}
+
 // Suppress interactive auth side-effects (e.g. Gemini CLI opening a Google
 // sign-in URL in the browser) when probing an ACP agent for models/modes.
 // NO_BROWSER is honored by Gemini CLI; other ACP agents ignore it.
@@ -359,6 +371,7 @@ interface ACPAgentClientOptions {
   sessionResponseTransformer?: (response: SessionStateResponse) => SessionStateResponse;
   configOptionsTransformer?: (configOptions: SessionConfigOption[]) => SessionConfigOption[];
   configFeatureOptions?: ACPConfigFeatureOption[];
+  clientCapabilityMeta?: ACPClientCapabilityMeta;
   modeIdTransformer?: (modeId: string) => string | null;
   toolSnapshotTransformer?: (snapshot: ACPToolSnapshot) => ACPToolSnapshot;
   providerModeWriter?: (
@@ -387,6 +400,7 @@ interface ACPAgentSessionOptions {
   sessionResponseTransformer?: (response: SessionStateResponse) => SessionStateResponse;
   configOptionsTransformer?: (configOptions: SessionConfigOption[]) => SessionConfigOption[];
   configFeatureOptions?: ACPConfigFeatureOption[];
+  clientCapabilityMeta?: ACPClientCapabilityMeta;
   modeIdTransformer?: (modeId: string) => string | null;
   toolSnapshotTransformer?: (snapshot: ACPToolSnapshot) => ACPToolSnapshot;
   providerModeWriter?: (
@@ -486,7 +500,7 @@ interface ConfigOptionSelector {
 export interface ACPConfigFeatureOption {
   id: string;
   configId: string;
-  category: string;
+  category?: string;
   label: string;
   description?: string;
   tooltip?: string;
@@ -694,6 +708,7 @@ export class ACPAgentClient implements AgentClient {
     configOptions: SessionConfigOption[],
   ) => SessionConfigOption[];
   private readonly configFeatureOptions: ACPConfigFeatureOption[];
+  private readonly clientCapabilityMeta?: ACPClientCapabilityMeta;
   private readonly modeIdTransformer?: (modeId: string) => string | null;
   private readonly toolSnapshotTransformer?: (snapshot: ACPToolSnapshot) => ACPToolSnapshot;
   private readonly providerModeWriter?: (
@@ -727,6 +742,7 @@ export class ACPAgentClient implements AgentClient {
     this.sessionResponseTransformer = options.sessionResponseTransformer;
     this.configOptionsTransformer = options.configOptionsTransformer;
     this.configFeatureOptions = options.configFeatureOptions ?? [];
+    this.clientCapabilityMeta = options.clientCapabilityMeta;
     this.modeIdTransformer = options.modeIdTransformer;
     this.toolSnapshotTransformer = options.toolSnapshotTransformer;
     this.providerModeWriter = options.providerModeWriter;
@@ -754,6 +770,7 @@ export class ACPAgentClient implements AgentClient {
         sessionResponseTransformer: this.sessionResponseTransformer,
         configOptionsTransformer: this.configOptionsTransformer,
         configFeatureOptions: this.configFeatureOptions,
+        clientCapabilityMeta: this.clientCapabilityMeta,
         modeIdTransformer: this.modeIdTransformer,
         toolSnapshotTransformer: this.toolSnapshotTransformer,
         providerModeWriter: this.providerModeWriter,
@@ -802,6 +819,7 @@ export class ACPAgentClient implements AgentClient {
       sessionResponseTransformer: this.sessionResponseTransformer,
       configOptionsTransformer: this.configOptionsTransformer,
       configFeatureOptions: this.configFeatureOptions,
+      clientCapabilityMeta: this.clientCapabilityMeta,
       modeIdTransformer: this.modeIdTransformer,
       toolSnapshotTransformer: this.toolSnapshotTransformer,
       providerModeWriter: this.providerModeWriter,
@@ -1039,7 +1057,7 @@ export class ACPAgentClient implements AgentClient {
         Promise.race([
           transport.connection.initialize({
             protocolVersion: PROTOCOL_VERSION,
-            clientCapabilities: ACP_CLIENT_CAPABILITIES,
+            clientCapabilities: buildACPClientCapabilities(this.clientCapabilityMeta),
             clientInfo: { name: "Paseo", version: "dev" },
           }),
           transport.spawnError,
@@ -1251,6 +1269,7 @@ export class ACPAgentSession implements AgentSession, ACPClient {
     configOptions: SessionConfigOption[],
   ) => SessionConfigOption[];
   private readonly configFeatureOptions: ACPConfigFeatureOption[];
+  private readonly clientCapabilityMeta?: ACPClientCapabilityMeta;
   private readonly modeIdTransformer?: (modeId: string) => string | null;
   private readonly toolSnapshotTransformer?: (snapshot: ACPToolSnapshot) => ACPToolSnapshot;
   private readonly providerModeWriter?: (
@@ -1315,6 +1334,7 @@ export class ACPAgentSession implements AgentSession, ACPClient {
     this.sessionResponseTransformer = options.sessionResponseTransformer;
     this.configOptionsTransformer = options.configOptionsTransformer;
     this.configFeatureOptions = options.configFeatureOptions ?? [];
+    this.clientCapabilityMeta = options.clientCapabilityMeta;
     this.modeIdTransformer = options.modeIdTransformer;
     this.toolSnapshotTransformer = options.toolSnapshotTransformer;
     this.providerModeWriter = options.providerModeWriter;
@@ -1890,16 +1910,19 @@ export class ACPAgentSession implements AgentSession, ACPClient {
   }: {
     response: { configOptions: SessionConfigOption[] };
     configId: string;
-    category: string;
+    category?: string;
     requestedValue: string;
     label: string;
   }): string {
     this.configOptions = this.transformConfigOptions(response.configOptions);
-    const responseOption = findSelectConfigOption({
+    const responseOption =
-      configOptions: this.configOptions,
+      category === undefined
-      category,
+        ? findSelectConfigOptionById({ configOptions: this.configOptions, id: configId })
-      id: configId,
+        : findSelectConfigOption({
-    });
+            configOptions: this.configOptions,
+            category,
+            id: configId,
+          });
     if (responseOption?.currentValue != null) {
       return responseOption.currentValue;
     }
@@ -2297,7 +2320,7 @@ export class ACPAgentSession implements AgentSession, ACPClient {
     const initialize = await this.runACPRequest(() =>
       connection.initialize({
         protocolVersion: PROTOCOL_VERSION,
-        clientCapabilities: ACP_CLIENT_CAPABILITIES,
+        clientCapabilities: buildACPClientCapabilities(this.clientCapabilityMeta),
         clientInfo: { name: "Paseo", version: "dev" },
       }),
     );
@@ -2743,6 +2766,19 @@ function findSelectConfigOption({
   return option ?? null;
 }
 
+function findSelectConfigOptionById({
+  configOptions,
+  id,
+}: {
+  configOptions: SessionConfigOption[] | null | undefined;
+  id: string;
+}): SelectConfigOption | null {
+  const option = configOptions?.find(
+    (entry): entry is SelectConfigOption => entry.type === "select" && entry.id === id,
+  );
+  return option ?? null;
+}
+
 function findSelectConfigFeatureOption(
   configOptions: SessionConfigOption[] | null | undefined,
   featureOption: ACPConfigFeatureOption,
@@ -2751,7 +2787,7 @@ function findSelectConfigFeatureOption(
     (entry): entry is SelectConfigOption =>
       entry.type === "select" &&
       entry.id === featureOption.configId &&
-      entry.category === featureOption.category,
+      (featureOption.category === undefined || entry.category === featureOption.category),
   );
   return option ?? null;
 }

packages/server/src/server/agent/providers/cursor-acp-agent.test.ts

@@ -1,10 +1,22 @@
 import { describe, expect, test, vi } from "vitest";
 
 import type { SpawnedACPProcess, SessionStateResponse } from "./acp-agent.js";
-import { CursorACPAgentClient } from "./cursor-acp-agent.js";
+import { CURSOR_FAST_FEATURE_OPTION, CursorACPAgentClient } from "./cursor-acp-agent.js";
 import { createTestLogger } from "../../../test-utils/test-logger.js";
 
 describe("CursorACPAgentClient model discovery", () => {
+  function fastConfigOption(currentValue: "false" | "true") {
+    return {
+      id: "fast",
+      name: "Fast",
+      type: "select" as const,
+      currentValue,
+      options: [
+        { value: "false", name: "Off" },
+        { value: "true", name: "Fast" },
+      ],
+    };
+  }
   class TestCursorACPAgentClient extends CursorACPAgentClient {
     constructor(response: SessionStateResponse) {
       super({
@@ -77,4 +89,79 @@ describe("CursorACPAgentClient model discovery", () => {
       modes: [],
     });
   });
+
+  test("keeps modern Cursor models as plain ACP ids", async () => {
+    const client = new TestCursorACPAgentClient({
+      sessionId: "session-1",
+      models: {
+        currentModelId: "composer-2.5",
+        availableModels: [
+          {
+            modelId: "composer-2.5",
+            name: "Composer 2.5",
+            description: null,
+          },
+        ],
+      },
+      configOptions: [fastConfigOption("false")],
+    });
+
+    await expect(
+      client.fetchCatalog({ scope: "workspace", cwd: "/tmp/cursor", force: false }),
+    ).resolves.toEqual({
+      models: [
+        {
+          provider: "acp",
+          id: "composer-2.5",
+          label: "Composer 2.5",
+          description: undefined,
+          isDefault: true,
+          thinkingOptions: undefined,
+          defaultThinkingOptionId: undefined,
+        },
+      ],
+      modes: [],
+    });
+  });
+
+  test("exposes Cursor fast mode through provider features", async () => {
+    const client = new TestCursorACPAgentClient({
+      sessionId: "session-1",
+      models: null,
+      configOptions: [fastConfigOption("false")],
+    });
+
+    await expect(
+      client.listFeatures({
+        provider: "acp",
+        cwd: "/tmp/cursor",
+      }),
+    ).resolves.toEqual([
+      {
+        type: "select",
+        id: CURSOR_FAST_FEATURE_OPTION.id,
+        label: "Fast",
+        description: "Cursor fast mode",
+        tooltip: "Select Cursor fast mode",
+        icon: "zap",
+        value: "false",
+        options: [
+          {
+            id: "false",
+            label: "Off",
+            isDefault: true,
+            description: undefined,
+            metadata: undefined,
+          },
+          {
+            id: "true",
+            label: "Fast",
+            isDefault: false,
+            description: undefined,
+            metadata: undefined,
+          },
+        ],
+      },
+    ]);
+  });
 });

packages/server/src/server/agent/providers/cursor-acp-agent.ts

@@ -1,5 +1,6 @@
 import type { Logger } from "pino";
 
+import type { ACPConfigFeatureOption } from "./acp-agent.js";
 import { GenericACPAgentClient } from "./generic-acp-agent.js";
 
 interface CursorACPAgentClientOptions {
@@ -12,6 +13,18 @@ interface CursorACPAgentClientOptions {
 }
 
 const CURSOR_INITIAL_COMMANDS_WAIT_TIMEOUT_MS = 10_000;
+const CURSOR_CLIENT_CAPABILITY_META = {
+  parameterizedModelPicker: true,
+};
+
+export const CURSOR_FAST_FEATURE_OPTION: ACPConfigFeatureOption = {
+  id: "fast",
+  configId: "fast",
+  label: "Fast",
+  description: "Cursor fast mode",
+  tooltip: "Select Cursor fast mode",
+  icon: "zap",
+};
 
 export class CursorACPAgentClient extends GenericACPAgentClient {
   constructor(options: CursorACPAgentClientOptions) {
@@ -25,6 +38,8 @@ export class CursorACPAgentClient extends GenericACPAgentClient {
       // cursor-agent publishes slash commands asynchronously via available_commands_update.
       waitForInitialCommands: true,
       initialCommandsWaitTimeoutMs: CURSOR_INITIAL_COMMANDS_WAIT_TIMEOUT_MS,
+      clientCapabilityMeta: CURSOR_CLIENT_CAPABILITY_META,
+      configFeatureOptions: [CURSOR_FAST_FEATURE_OPTION],
     });
   }
 }

packages/server/src/server/agent/providers/generic-acp-agent.ts

@@ -5,6 +5,8 @@ import type { AgentCapabilityFlags } from "../agent-sdk-types.js";
 import { checkProviderLaunchAvailable, resolveProviderLaunch } from "../provider-launch-config.js";
 import {
   ACPAgentClient,
+  type ACPClientCapabilityMeta,
+  type ACPConfigFeatureOption,
   DEFAULT_ACP_CAPABILITIES,
   type ACPExtensionCommandsParser,
 } from "./acp-agent.js";
@@ -33,6 +35,8 @@ interface GenericACPAgentClientOptions {
   waitForInitialCommands?: boolean;
   initialCommandsWaitTimeoutMs?: number;
   diagnosticPhaseTimeoutMs?: number;
+  clientCapabilityMeta?: ACPClientCapabilityMeta;
+  configFeatureOptions?: ACPConfigFeatureOption[];
   extensionCommandsParser?: ACPExtensionCommandsParser;
 }
 
@@ -53,6 +57,8 @@ export class GenericACPAgentClient extends ACPAgentClient {
       capabilities: buildGenericACPCapabilities(options),
       waitForInitialCommands: options.waitForInitialCommands,
       initialCommandsWaitTimeoutMs: options.initialCommandsWaitTimeoutMs,
+      clientCapabilityMeta: options.clientCapabilityMeta,
+      configFeatureOptions: options.configFeatureOptions,
       extensionCommandsParser: options.extensionCommandsParser,
     });