diff --git a/src/renderer/src/aiCore/middleware/AiSdkMiddlewareBuilder.ts b/src/renderer/src/aiCore/middleware/AiSdkMiddlewareBuilder.ts
index 20b89cf2e5..e2b253374b 100644
--- a/src/renderer/src/aiCore/middleware/AiSdkMiddlewareBuilder.ts
+++ b/src/renderer/src/aiCore/middleware/AiSdkMiddlewareBuilder.ts
@@ -4,6 +4,8 @@ import type { MCPTool, Message, Model, Provider } from '@renderer/types'
 import type { Chunk } from '@renderer/types/chunk'
 import { extractReasoningMiddleware, LanguageModelMiddleware, simulateStreamingMiddleware } from 'ai'
 
+import { toolChoiceMiddleware } from './toolChoiceMiddleware'
+
 const logger = loggerService.withContext('AiSdkMiddlewareBuilder')
 
 /**
@@ -29,6 +31,8 @@ export interface AiSdkMiddlewareConfig {
   uiMessages?: Message[]
   // 内置搜索配置
   webSearchPluginConfig?: WebSearchPluginConfig
+  // 知识库识别开关，默认开启
+  knowledgeRecognition?: 'off' | 'on'
 }
 
 /**
@@ -119,6 +123,15 @@ export class AiSdkMiddlewareBuilder {
 export function buildAiSdkMiddlewares(config: AiSdkMiddlewareConfig): LanguageModelMiddleware[] {
   const builder = new AiSdkMiddlewareBuilder()
 
+  // 0. 知识库强制调用中间件（必须在最前面，确保第一轮强制调用知识库）
+  if (config.knowledgeRecognition === 'off') {
+    builder.add({
+      name: 'force-knowledge-first',
+      middleware: toolChoiceMiddleware('builtin_knowledge_search')
+    })
+    logger.debug('Added toolChoice middleware to force knowledge base search on first round')
+  }
+
   // 1. 根据provider添加特定中间件
   if (config.provider) {
     addProviderSpecificMiddlewares(builder, config)
diff --git a/src/renderer/src/aiCore/middleware/toolChoiceMiddleware.ts b/src/renderer/src/aiCore/middleware/toolChoiceMiddleware.ts
new file mode 100644
index 0000000000..6d3ba37d1d
--- /dev/null
+++ b/src/renderer/src/aiCore/middleware/toolChoiceMiddleware.ts
@@ -0,0 +1,45 @@
+import { loggerService } from '@logger'
+import { LanguageModelMiddleware } from 'ai'
+
+const logger = loggerService.withContext('toolChoiceMiddleware')
+
+/**
+ * Tool Choice Middleware
+ * Controls tool selection strategy across multiple rounds of tool calls:
+ * - First round: Forces the model to call a specific tool (e.g., knowledge base search)
+ * - Subsequent rounds: Allows the model to automatically choose any available tool
+ *
+ * This ensures knowledge base is consulted first while still enabling MCP tools
+ * and other capabilities in follow-up interactions.
+ *
+ * @param forceFirstToolName - The tool name to force on the first round
+ * @returns LanguageModelMiddleware
+ */
+export function toolChoiceMiddleware(forceFirstToolName: string): LanguageModelMiddleware {
+  let toolCallRound = 0
+
+  return {
+    middlewareVersion: 'v2',
+
+    transformParams: async ({ params }) => {
+      toolCallRound++
+
+      const transformedParams = { ...params }
+
+      if (toolCallRound === 1) {
+        // First round: force the specified tool
+        logger.debug(`Round ${toolCallRound}: Forcing tool choice to '${forceFirstToolName}'`)
+        transformedParams.toolChoice = {
+          type: 'tool',
+          toolName: forceFirstToolName
+        }
+      } else {
+        // Subsequent rounds: allow automatic tool selection
+        logger.debug(`Round ${toolCallRound}: Using automatic tool choice`)
+        transformedParams.toolChoice = { type: 'auto' }
+      }
+
+      return transformedParams
+    }
+  }
+}
diff --git a/src/renderer/src/services/ApiService.ts b/src/renderer/src/services/ApiService.ts
index 6ab07662cb..403fdc2cfe 100644
--- a/src/renderer/src/services/ApiService.ts
+++ b/src/renderer/src/services/ApiService.ts
@@ -138,7 +138,8 @@ export async function fetchChatCompletion({
     enableGenerateImage: capabilities.enableGenerateImage,
     enableUrlContext: capabilities.enableUrlContext,
     mcpTools,
-    uiMessages
+    uiMessages,
+    knowledgeRecognition: assistant.knowledgeRecognition
   }
 
   // --- Call AI Completions ---