refactor(cli): switch useToolScheduler to event-driven engine (#18565)

packages/cli/src/test-utils/mockConfig.ts

@@ -45,7 +45,6 @@ export const createMockConfig = (overrides: Partial<Config> = {}): Config =>
     setRemoteAdminSettings: vi.fn(),
     isYoloModeDisabled: vi.fn(() => false),
     isPlanEnabled: vi.fn(() => false),
-    isEventDrivenSchedulerEnabled: vi.fn(() => false),
     getCoreTools: vi.fn(() => []),
     getAllowedTools: vi.fn(() => []),
     getApprovalMode: vi.fn(() => 'default'),

packages/cli/src/ui/hooks/useGeminiStream.ts

@@ -389,7 +389,6 @@ export const useGeminiStream = (
       toolCalls.length > 0 &&
       toolCalls.every((tc) => pushedToolCallIds.has(tc.request.callId));
 
-    const isEventDriven = config.isEventDrivenSchedulerEnabled();
     const anyVisibleInHistory = pushedToolCallIds.size > 0;
     const anyVisibleInPending = remainingTools.some((tc) => {
       // AskUser tools are rendered by AskUserDialog, not ToolGroupMessage
@@ -400,7 +399,6 @@ export const useGeminiStream = (
       if (tc.request.name === ASK_USER_TOOL_NAME && isInProgress) {
         return false;
       }
-      if (!isEventDriven) return true;
       return (
         tc.status !== 'scheduled' &&
         tc.status !== 'validating' &&
@@ -422,7 +420,7 @@ export const useGeminiStream = (
     }
 
     return items;
-  }, [toolCalls, pushedToolCallIds, config]);
+  }, [toolCalls, pushedToolCallIds]);
 
   const activeToolPtyId = useMemo(() => {
     const executingShellTool = toolCalls.find(

packages/cli/src/ui/hooks/useToolScheduler.ts

@@ -11,8 +11,6 @@ import type {
   ToolCallRequestInfo,
 } from '@google/gemini-cli-core';
 import {
-  useReactToolScheduler,
-  type TrackedToolCall as LegacyTrackedToolCall,
   type TrackedScheduledToolCall,
   type TrackedValidatingToolCall,
   type TrackedWaitingToolCall,
@@ -24,12 +22,13 @@ import {
 } from './useReactToolScheduler.js';
 import {
   useToolExecutionScheduler,
-  type TrackedToolCall as NewTrackedToolCall,
+  type TrackedToolCall,
 } from './useToolExecutionScheduler.js';
 
 // Re-export specific state types from Legacy, as the structures are compatible
 // and useGeminiStream relies on them for narrowing.
 export type {
+  TrackedToolCall,
   TrackedScheduledToolCall,
   TrackedValidatingToolCall,
   TrackedWaitingToolCall,
@@ -40,9 +39,6 @@ export type {
   CancelAllFn,
 };
 
-// Unified type that covers both implementations
-export type TrackedToolCall = LegacyTrackedToolCall | NewTrackedToolCall;
-
 // Unified Schedule function (Promise<void> | Promise<CompletedToolCall[]>)
 export type ScheduleFn = (
   request: ToolCallRequestInfo | ToolCallRequestInfo[],
@@ -59,30 +55,16 @@ export type UseToolSchedulerReturn = [
 ];
 
 /**
- * Facade hook that switches between the Legacy and Event-Driven schedulers
- * based on configuration.
- *
- * Note: This conditionally calls hooks, which technically violates the standard
- * Rules of Hooks linting. However, this is safe here because
- * `config.isEventDrivenSchedulerEnabled()` is static for the lifetime of the
- * application session (it essentially acts as a compile-time feature flag).
+ * Hook that uses the Event-Driven scheduler for tool execution.
  */
 export function useToolScheduler(
   onComplete: (tools: CompletedToolCall[]) => Promise<void>,
   config: Config,
   getPreferredEditor: () => EditorType | undefined,
 ): UseToolSchedulerReturn {
-  const isEventDriven = config.isEventDrivenSchedulerEnabled();
-
-  // Note: We return the hooks directly without casting. They return compatible
-  // tuple structures, but use explicit tuple signatures rather than the
-  // UseToolSchedulerReturn named type to avoid circular dependencies back to
-  // this facade.
-  if (isEventDriven) {
-    // eslint-disable-next-line react-hooks/rules-of-hooks
-    return useToolExecutionScheduler(onComplete, config, getPreferredEditor);
-  }
-
-  // eslint-disable-next-line react-hooks/rules-of-hooks
-  return useReactToolScheduler(onComplete, config, getPreferredEditor);
+  return useToolExecutionScheduler(
+    onComplete,
+    config,
+    getPreferredEditor,
+  ) as UseToolSchedulerReturn;
 }

packages/cli/src/ui/hooks/useToolSchedulerFacade.test.ts

@@ -1,70 +0,0 @@
-/**
- * @license
- * Copyright 2026 Google LLC
- * SPDX-License-Identifier: Apache-2.0
- */
-
-import { describe, it, expect, vi, beforeEach } from 'vitest';
-import { renderHook } from '../../test-utils/render.js';
-import { useToolScheduler } from './useToolScheduler.js';
-import { useReactToolScheduler } from './useReactToolScheduler.js';
-import { useToolExecutionScheduler } from './useToolExecutionScheduler.js';
-import type { Config } from '@google/gemini-cli-core';
-
-vi.mock('./useReactToolScheduler.js', () => ({
-  useReactToolScheduler: vi.fn().mockReturnValue(['legacy']),
-}));
-
-vi.mock('./useToolExecutionScheduler.js', () => ({
-  useToolExecutionScheduler: vi.fn().mockReturnValue(['modern']),
-}));
-
-describe('useToolScheduler (Facade)', () => {
-  let mockConfig: Config;
-
-  beforeEach(() => {
-    vi.clearAllMocks();
-  });
-
-  it('delegates to useReactToolScheduler when event-driven scheduler is disabled', () => {
-    mockConfig = {
-      isEventDrivenSchedulerEnabled: () => false,
-    } as unknown as Config;
-
-    const onComplete = vi.fn();
-    const getPreferredEditor = vi.fn();
-
-    const { result } = renderHook(() =>
-      useToolScheduler(onComplete, mockConfig, getPreferredEditor),
-    );
-
-    expect(result.current).toEqual(['legacy']);
-    expect(useReactToolScheduler).toHaveBeenCalledWith(
-      onComplete,
-      mockConfig,
-      getPreferredEditor,
-    );
-    expect(useToolExecutionScheduler).not.toHaveBeenCalled();
-  });
-
-  it('delegates to useToolExecutionScheduler when event-driven scheduler is enabled', () => {
-    mockConfig = {
-      isEventDrivenSchedulerEnabled: () => true,
-    } as unknown as Config;
-
-    const onComplete = vi.fn();
-    const getPreferredEditor = vi.fn();
-
-    const { result } = renderHook(() =>
-      useToolScheduler(onComplete, mockConfig, getPreferredEditor),
-    );
-
-    expect(result.current).toEqual(['modern']);
-    expect(useToolExecutionScheduler).toHaveBeenCalledWith(
-      onComplete,
-      mockConfig,
-      getPreferredEditor,
-    );
-    expect(useReactToolScheduler).not.toHaveBeenCalled();
-  });
-});