fix(wand): remove duplicate transfer encoding header meant to be set by nginx proxy (#1221)

Author: waleedlatif1

apps/sim/app/api/wand-generate/route.ts

@@ -49,7 +49,6 @@ interface RequestBody {
   history?: ChatMessage[]
 }
 
-// Helper: safe stringify for error payloads that may include circular structures
 function safeStringify(value: unknown): string {
   try {
     return JSON.stringify(value)
@@ -83,18 +82,14 @@ export async function POST(req: NextRequest) {
       )
     }
 
-    // Use provided system prompt or default
     const finalSystemPrompt =
       systemPrompt ||
       'You are a helpful AI assistant. Generate content exactly as requested by the user.'
 
-    // Prepare messages for OpenAI API
     const messages: ChatMessage[] = [{ role: 'system', content: finalSystemPrompt }]
 
-    // Add previous messages from history
     messages.push(...history.filter((msg) => msg.role !== 'system'))
 
-    // Add the current user prompt
     messages.push({ role: 'user', content: prompt })
 
     logger.debug(
@@ -108,7 +103,6 @@ export async function POST(req: NextRequest) {
       }
     )
 
-    // For streaming responses
     if (stream) {
       try {
         logger.debug(
@@ -119,7 +113,6 @@ export async function POST(req: NextRequest) {
           `[${requestId}] About to create stream with model: ${useWandAzure ? wandModelName : 'gpt-4o'}`
         )
 
-        // Use native fetch for streaming to avoid OpenAI SDK issues with Node.js runtime
         const apiUrl = useWandAzure
           ? `${azureEndpoint}/openai/deployments/${wandModelName}/chat/completions?api-version=${azureApiVersion}`
           : 'https://api.openai.com/v1/chat/completions'
@@ -161,7 +154,6 @@ export async function POST(req: NextRequest) {
 
         logger.info(`[${requestId}] Stream response received, starting processing`)
 
-        // Create a TransformStream to process the SSE data
         const encoder = new TextEncoder()
         const decoder = new TextDecoder()
 
@@ -187,12 +179,10 @@ export async function POST(req: NextRequest) {
                   break
                 }
 
-                // Decode the chunk
                 buffer += decoder.decode(value, { stream: true })
 
-                // Process complete SSE messages
                 const lines = buffer.split('\n')
-                buffer = lines.pop() || '' // Keep incomplete line in buffer
+                buffer = lines.pop() || ''
 
                 for (const line of lines) {
                   if (line.startsWith('data: ')) {
@@ -217,25 +207,21 @@ export async function POST(req: NextRequest) {
                           logger.info(`[${requestId}] Received first content chunk`)
                         }
 
-                        // Forward the content
                         controller.enqueue(
                           encoder.encode(`data: ${JSON.stringify({ chunk: content })}\n\n`)
                         )
                       }
 
-                      // Log usage if present
                       if (parsed.usage) {
                         logger.info(
                           `[${requestId}] Received usage data: ${JSON.stringify(parsed.usage)}`
                         )
                       }
 
-                      // Log progress periodically
                       if (chunkCount % 10 === 0) {
                         logger.debug(`[${requestId}] Processed ${chunkCount} chunks`)
                       }
                     } catch (parseError) {
-                      // Skip invalid JSON lines
                       logger.debug(
                         `[${requestId}] Skipped non-JSON line: ${data.substring(0, 100)}`
                       )
@@ -252,7 +238,6 @@ export async function POST(req: NextRequest) {
                 stack: streamError?.stack,
               })
 
-              // Send error to client
               const errorData = `data: ${JSON.stringify({ error: 'Streaming failed', done: true })}\n\n`
               controller.enqueue(encoder.encode(errorData))
               controller.close()
@@ -262,14 +247,12 @@ export async function POST(req: NextRequest) {
           },
         })
 
-        // Return Response with proper headers for Node.js runtime
         return new Response(readable, {
           headers: {
             'Content-Type': 'text/event-stream',
             'Cache-Control': 'no-cache, no-transform',
             Connection: 'keep-alive',
-            'X-Accel-Buffering': 'no', // Disable Nginx buffering
-            'Transfer-Encoding': 'chunked', // Important for Node.js runtime
+            'X-Accel-Buffering': 'no',
           },
         })
       } catch (error: any) {
@@ -294,7 +277,6 @@ export async function POST(req: NextRequest) {
       }
     }
 
-    // For non-streaming responses
     const completion = await client.chat.completions.create({
       model: useWandAzure ? wandModelName : 'gpt-4o',
       messages: messages,