feat: add GET endpoint for retrieving background job as a streamed response

Author: nickytonline

src/routes/api/background-jobs.ts

@@ -1,5 +1,10 @@
 import { createServerFileRoute } from '@tanstack/react-start/server'
-import { handleJobStatusRequest, BackgroundJobError } from '@/lib/background-jobs'
+import {
+  handleJobStatusRequest,
+  BackgroundJobError,
+} from '@/lib/background-jobs'
+import { streamText } from '@/lib/streaming'
+import OpenAI from 'openai'
 
 export const ServerRoute = createServerFileRoute(
   '/api/background-jobs',
@@ -17,7 +22,7 @@ export const ServerRoute = createServerFileRoute(
       console.error('Error in background jobs route:', error)
 
       if (error instanceof BackgroundJobError) {
-        const responseBody = error.message.startsWith('{') 
+        const responseBody = error.message.startsWith('{')
           ? error.message // Already JSON string for validation errors
           : JSON.stringify({ error: error.message })
 
@@ -33,4 +38,72 @@ export const ServerRoute = createServerFileRoute(
       })
     }
   },
+  async GET({ request }) {
+    const url = new URL(request.url)
+    const backgroundJobId = url.searchParams.get('id')
+
+    if (!backgroundJobId) {
+      return new Response(
+        JSON.stringify({ error: 'Background job ID is required' }),
+        {
+          status: 400,
+          headers: { 'Content-Type': 'application/json' },
+        },
+      )
+    }
+
+    const client = new OpenAI()
+
+    try {
+      const response = await client.responses.retrieve(backgroundJobId, {
+        stream: true,
+      })
+
+      return streamText(response)
+    } catch (error) {
+      console.error('Error retrieving OpenAI response:', error)
+
+      if (error instanceof OpenAI.APIError) {
+        const statusCode = error.status || 500
+        let clientMessage = 'Failed to check background job status'
+
+        switch (statusCode) {
+          case 404:
+            clientMessage = 'Background job not found'
+            break
+          case 401:
+            clientMessage = 'Authentication failed'
+            break
+          case 403:
+            clientMessage = 'Access denied'
+            break
+          case 429:
+            clientMessage = 'Rate limit exceeded'
+            break
+        }
+
+        return new Response(
+          JSON.stringify({
+            status: 'failed',
+            error: clientMessage,
+          }),
+          {
+            status: 200,
+            headers: { 'Content-Type': 'application/json' },
+          },
+        )
+      }
+
+      return new Response(
+        JSON.stringify({
+          status: 'failed',
+          error: 'Internal server error',
+        }),
+        {
+          status: 500,
+          headers: { 'Content-Type': 'application/json' },
+        },
+      )
+    }
+  },
 })