feat: 提升 LangChain 回调处理的健壮性并为 Langfuse 跟踪添加会话和用户 ID。

Author: OSpoon

backend/app/services/ai_provider_service.ts

@@ -71,7 +71,7 @@ export default class AiProviderService {
     const rawTranscriptionApiKey = transcriptionApiKeySetting?.value
     const transcriptionApiKey
       = rawTranscriptionApiKey && rawTranscriptionApiKey !== 'null'
-        ? CryptoHelper.tryDecrypt(rawTranscriptionApiKey)
+        ? CryptoHelper.tryDecrypt(rawTranscriptionApiKey) ?? undefined
         : undefined
     const transcriptionModel = transcriptionModelSetting?.value
 
@@ -92,7 +92,14 @@ export default class AiProviderService {
   /**
    * Get Langfuse Callback Handler for tracing
    */
-  public getLangfuseHandler(options: { tags?: string[], metadata?: Record<string, any> } = {}) {
+  public getLangfuseHandler(
+    options: {
+      tags?: string[]
+      metadata?: Record<string, any>
+      sessionId?: string
+      userId?: string
+    } = {},
+  ) {
     if (env.get('LANGFUSE_PUBLIC_KEY')) {
       return new CallbackHandler(options)
     }

backend/app/services/evaluation_service.ts

@@ -84,7 +84,8 @@ export default class EvaluationService {
         dataSourceId: 9999, // 虚拟 ID，映射到当前的评测 SQLite 文件
       }
 
-      const result = await graph.invoke(inputs, { callbacks: [traceHandler] })
+      const callbacks = [traceHandler].filter((h): h is NonNullable<typeof h> => !!h)
+      const result = await graph.invoke(inputs, { callbacks })
       generatedSql = (result.sql || '').trim()
       errorMsg = result.error || ''
 

backend/app/services/lang_chain_service.ts

@@ -91,7 +91,8 @@ export default class LangChainService {
         tags: ['general_chat'],
       })
 
-      const { llm: model } = await this.getModel(false, undefined, [traceHandler])
+      const callbacks = [traceHandler].filter((h): h is NonNullable<typeof h> => !!h)
+      const { llm: model } = await this.getModel(false, undefined, callbacks)
       const messages: BaseMessage[] = [new SystemMessage(systemPrompt)]
       for (const m of context.history || []) {
         if (m.role === 'user')
@@ -180,10 +181,11 @@ export default class LangChainService {
 
     try {
       // Use streamEvents to capture tokens and tool events
+      const callbacks = [traceHandler].filter((h): h is NonNullable<typeof h> => !!h)
       const stream = app.streamEvents(inputs, {
         version: 'v2',
         recursionLimit: 10,
-        callbacks: [traceHandler],
+        callbacks,
       })
 
       const streamState: StreamState = {
@@ -367,7 +369,8 @@ export default class LangChainService {
 
     const config = await aiProvider.getConfig()
     const modelName = config.chatModel
-    const { llm } = await this.getModel(false, undefined, [traceHandler])
+    const callbacks = [traceHandler].filter((h): h is NonNullable<typeof h> => !!h)
+    const { llm } = await this.getModel(false, undefined, callbacks)
     const dbType = context.dbType || 'mysql'
 
     const prompt = SQL_OPTIMIZATION_PROMPT_TEMPLATE(