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

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Merged
waleedlatif1 merged 1 commit into from
Sep 2, 2025
Merged

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

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22 changes: 2 additions & 20 deletions apps/sim/app/api/wand-generate/route.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand Down Expand Up @@ -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(
Expand All @@ -108,7 +103,6 @@ export async function POST(req: NextRequest) {
}
)

// For streaming responses
if (stream) {
try {
logger.debug(
Expand All @@ -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'
Expand Down Expand Up @@ -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()

Expand All @@ -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: ')) {
Expand All @@ -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)}`
)
Expand All @@ -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()
Expand All @@ -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) {
Expand All @@ -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,
Expand Down