docs: 添加 ToolSearch 设计指南 + 禁用 turn-zero 工具推荐弹窗

- 新增 docs/design/tool-search-design-guide.md，涵盖架构、搜索算法、执行管道、演进历史
- 禁用 getTurnZeroSearchExtraToolsPrefetch，消除用户输入时的频繁弹窗
- inter-turn 发现机制保持不变

Co-Authored-By: glm-5-turbo <zai-org@claude-code-best.win>

packages/builtin-tools/src/tools/SearchExtraToolsTool/__tests__/SearchExtraToolsTool.test.ts

@@ -0,0 +1,235 @@
+import { describe, test, expect } from 'bun:test'
+import { mock } from 'bun:test'
+import { logMock } from '../../../../../../tests/mocks/log'
+import { debugMock } from '../../../../../../tests/mocks/debug'
+
+mock.module('src/utils/log.ts', logMock)
+mock.module('src/utils/debug.ts', debugMock)
+
+mock.module('src/services/analytics/growthbook.js', () => ({
+  getFeatureValue_CACHED_MAY_BE_STALE: () => false,
+  checkStatsigFeatureGate_CACHED_MAY_BE_STALE: () => false,
+  getFeatureValue_DEPRECATED: async () => undefined,
+  getFeatureValue_CACHED_WITH_REFRESH: async () => undefined,
+  hasGrowthBookEnvOverride: () => false,
+  getAllGrowthBookFeatures: () => ({}),
+  getGrowthBookConfigOverrides: () => ({}),
+  setGrowthBookConfigOverride: () => {},
+  clearGrowthBookConfigOverrides: () => {},
+  getApiBaseUrlHost: () => undefined,
+  onGrowthBookRefresh: () => {},
+  initializeGrowthBook: async () => {},
+  checkSecurityRestrictionGate: async () => false,
+  checkGate_CACHED_OR_BLOCKING: async () => false,
+  refreshGrowthBookAfterAuthChange: () => {},
+  resetGrowthBook: () => {},
+  refreshGrowthBookFeatures: async () => {},
+  setupPeriodicGrowthBookRefresh: () => {},
+  stopPeriodicGrowthBookRefresh: () => {},
+}))
+
+mock.module('src/utils/searchExtraTools.js', () => ({
+  isSearchExtraToolsEnabledOptimistic: () => true,
+  getAutoSearchExtraToolsCharThreshold: () => 100,
+  getSearchExtraToolsMode: () => 'tst' as const,
+  isSearchExtraToolsToolAvailable: async () => true,
+  isSearchExtraToolsEnabled: async () => true,
+  isToolReferenceBlock: () => false,
+  extractDiscoveredToolNames: () => new Set(),
+  isDeferredToolsDeltaEnabled: () => false,
+  getDeferredToolsDelta: () => null,
+}))
+
+mock.module('src/constants/tools.js', () => ({
+  CORE_TOOLS: new Set(['Read', 'Edit', 'SearchExtraTools', 'ExecuteExtraTool']),
+}))
+
+// Mock toolIndex module
+type MockSearchExtraToolsResult = {
+  name: string
+  description: string
+  searchHint: string | undefined
+  score: number
+  isMcp: boolean
+  isDeferred: boolean
+  inputSchema: object | undefined
+}
+const mockSearchTools = mock(
+  (
+    _query: string,
+    _index: unknown,
+    _limit?: number,
+  ): MockSearchExtraToolsResult[] => [],
+)
+const mockGetToolIndex = mock(async (_tools: unknown) => [])
+
+mock.module('src/services/searchExtraTools/toolIndex.js', () => ({
+  getToolIndex: mockGetToolIndex,
+  searchTools: mockSearchTools,
+}))
+
+// Mock analytics
+mock.module('src/services/analytics/index.js', () => ({
+  logEvent: () => {},
+}))
+
+const { SearchExtraToolsTool } = await import('../SearchExtraToolsTool.js')
+
+function makeDeferredTool(name: string, desc: string = 'A tool') {
+  return {
+    name,
+    isMcp: false,
+    alwaysLoad: undefined,
+    shouldDefer: undefined,
+    searchHint: '',
+    prompt: async () => desc,
+    description: async () => desc,
+    inputSchema: {},
+    isEnabled: () => true,
+  }
+}
+
+function makeContext(tools: unknown[] = []) {
+  return {
+    options: { tools },
+    cwd: '/tmp',
+    sessionId: 'test',
+    getAppState: () => ({
+      mcp: { clients: [] },
+    }),
+  } as never
+}
+
+describe('SearchExtraToolsTool search enhancements', () => {
+  test('discover: prefix triggers TF-IDF search and returns matches', async () => {
+    const mockTool = makeDeferredTool('CronCreate', 'Schedule cron jobs')
+    mockGetToolIndex.mockResolvedValueOnce([])
+    mockSearchTools.mockReturnValueOnce([
+      {
+        name: 'CronCreate',
+        description: 'Schedule cron jobs',
+        searchHint: undefined,
+        score: 0.85,
+        isMcp: false,
+        isDeferred: true,
+        inputSchema: undefined,
+      },
+    ])
+
+    const result: { data: { matches: string[] } } = await (
+      SearchExtraToolsTool as any
+    ).call(
+      { query: 'discover:schedule cron job', max_results: 5 },
+      makeContext([mockTool]),
+      async () => ({ behavior: 'allow' }),
+      { type: 'assistant', content: [], uuid: 'msg1' } as never,
+      undefined,
+    )
+
+    expect(result.data.matches).toContain('CronCreate')
+  })
+
+  test('keyword + TF-IDF parallel search merges results', async () => {
+    const toolA = makeDeferredTool('ToolA', 'Tool A description')
+    const toolB = makeDeferredTool('ToolB', 'Tool B description')
+    const toolC = makeDeferredTool('ToolC', 'Tool C description')
+
+    // getToolIndex returns tools, searchTools returns different ranking
+    mockGetToolIndex.mockResolvedValueOnce([])
+    mockSearchTools.mockReturnValueOnce([
+      {
+        name: 'ToolB',
+        description: 'Tool B',
+        searchHint: undefined,
+        score: 0.9,
+        isMcp: false,
+        isDeferred: true,
+        inputSchema: undefined,
+      },
+      {
+        name: 'ToolC',
+        description: 'Tool C',
+        searchHint: undefined,
+        score: 0.8,
+        isMcp: false,
+        isDeferred: true,
+        inputSchema: undefined,
+      },
+    ])
+
+    const result: { data: { matches: string[] } } = await (
+      SearchExtraToolsTool as any
+    ).call(
+      { query: 'tool B', max_results: 5 },
+      makeContext([toolA, toolB, toolC]),
+      async () => ({ behavior: 'allow' }),
+      { type: 'assistant', content: [], uuid: 'msg1' } as never,
+      undefined,
+    )
+
+    // ToolB should be in results (matched by both keyword and TF-IDF)
+    expect(result.data.matches).toContain('ToolB')
+  })
+
+  test('text mode output for all models (unified self-built search)', async () => {
+    const tool = makeDeferredTool('TestTool', 'A test tool')
+    mockGetToolIndex.mockResolvedValueOnce([])
+    mockSearchTools.mockReturnValueOnce([])
+
+    // First call: search returns matches
+    mockSearchTools.mockReturnValueOnce([
+      {
+        name: 'TestTool',
+        description: 'A test',
+        searchHint: undefined,
+        score: 0.9,
+        isMcp: false,
+        isDeferred: true,
+        inputSchema: undefined,
+      },
+    ])
+
+    // mapToolResultToToolResultBlockParam always returns text, not tool_reference
+    const blockParam = SearchExtraToolsTool.mapToolResultToToolResultBlockParam(
+      { matches: ['TestTool'], query: 'test', total_deferred_tools: 1 },
+      'tool-use-123',
+      { mainLoopModel: 'claude-3-haiku-20240307' },
+    )
+
+    expect(typeof blockParam.content).toBe('string')
+    expect(blockParam.content as string).toContain('TestTool')
+    expect(blockParam.content as string).toContain('ExecuteExtraTool')
+  })
+
+  test('text output works for any model without distinction', async () => {
+    const blockParam = SearchExtraToolsTool.mapToolResultToToolResultBlockParam(
+      { matches: ['TestTool'], query: 'test', total_deferred_tools: 1 },
+      'tool-use-123',
+      { mainLoopModel: 'claude-sonnet-4-20250514' },
+    )
+
+    expect(typeof blockParam.content).toBe('string')
+    expect(blockParam.content as string).toContain('TestTool')
+    expect(blockParam.content as string).toContain('ExecuteExtraTool')
+  })
+
+  test('backwards compatible without context parameter', async () => {
+    const blockParam = SearchExtraToolsTool.mapToolResultToToolResultBlockParam(
+      { matches: ['TestTool'], query: 'test', total_deferred_tools: 1 },
+      'tool-use-123',
+    )
+
+    expect(typeof blockParam.content).toBe('string')
+    expect(blockParam.content as string).toContain('TestTool')
+    expect(blockParam.content as string).toContain('ExecuteExtraTool')
+  })
+
+  test('empty results return helpful message', async () => {
+    const blockParam = SearchExtraToolsTool.mapToolResultToToolResultBlockParam(
+      { matches: [], query: 'nonexistent', total_deferred_tools: 5 },
+      'tool-use-123',
+    )
+
+    expect(blockParam.content).toContain('No matching deferred tools found')
+  })
+})