feat: timeout on idle only (#98)

Change the maxout to 0.3 min and add sleep in rest api side and see:
<img width="929" alt="image"
src="https://github.com/landing-ai/vision-agent-ui/assets/132986242/383b5d3a-bba6-4f10-9eda-0f995800209a">
Change back to 2 min, and running normal prompt (The service is having
some issues due to the introduction of langsmith, so could not get the
image generated):
<img width="1450" alt="image"
src="https://github.com/landing-ai/vision-agent-ui/assets/132986242/092c37c7-4b39-4d90-871f-bf32f7f42ee8">

app/api/vision-agent/route.ts

@@ -211,14 +211,6 @@ export const POST = withLogging(
         };
 
         const processChunk = async (lines: string[]) => {
-          if (lines.length === 0) {
-            if (Date.now() - time > TIMEOUT_MILI_SECONDS) {
-              results.push(FINAL_TIMEOUT_ERROR);
-              return { done: true, reason: 'timeout' };
-            }
-          } else {
-            time = Date.now();
-          }
           buffer = lines.pop() ?? ''; // Save the last incomplete line back to the buffer
           for (let line of lines) {
             const { data: parsedMsg, error } = await parseLine(line);
@@ -287,44 +279,57 @@ export const POST = withLogging(
           return { done: false };
         };
 
-        // const parser = createParser(streamParser);
+        const onStreamFinish = async (
+          reason: string,
+          error?: Error | PrismaJson.StructuredError,
+        ) => {
+          const processMsgs = results.filter(
+            res => res.type !== 'final_code',
+          ) as PrismaJson.AgentResponseBodies;
+          await dbPostUpdateMessageResponse(messageId, {
+            response: processMsgs.map(res => JSON.stringify(res)).join('\n'),
+            result: results.find(
+              res => res.type === 'final_code',
+            ) as PrismaJson.FinalCodeBody,
+            responseBody: processMsgs,
+          });
+          logger.info(
+            session,
+            {
+              message: 'Streaming ended',
+              maxChunkSize,
+              reason,
+              error,
+            },
+            request,
+            error ? '__AGENT_DONE_WITH_ERROR' : '__AGENT_DONE',
+          );
+          // This is just using to trigger the onFinish event in useChat hooks
+          // but the message isn't used anywhere
+          // https://github.com/vercel/ai/blob/main/packages/ui-utils/src/call-chat-api.ts#L118
+          controller.enqueue(
+            encoder.encode('0:' + JSON.stringify('DONE') + '\n'),
+          );
+          controller.close();
+        };
+
+        let timeout = null;
         for await (const chunk of fetchResponse.body as any) {
           const data = decoder.decode(chunk);
           buffer += data;
           maxChunkSize = Math.max(data.length, maxChunkSize);
+          if (timeout) clearTimeout(timeout);
           const lines = buffer
             .split('\n')
             .filter(line => line.trim().length > 0);
           const { done, reason, error } = await processChunk(lines);
           if (done) {
-            const processMsgs = results.filter(
-              res => res.type !== 'final_code',
-            ) as PrismaJson.AgentResponseBodies;
-            await dbPostUpdateMessageResponse(messageId, {
-              response: processMsgs.map(res => JSON.stringify(res)).join('\n'),
-              result: results.find(
-                res => res.type === 'final_code',
-              ) as PrismaJson.FinalCodeBody,
-              responseBody: processMsgs,
-            });
-            logger.info(
-              session,
-              {
-                message: 'Streaming ended',
-                maxChunkSize,
-                reason,
-                error,
-              },
-              request,
-              '__AGENT_DONE',
-            );
-            // This is just using to trigger the onFinish event in useChat hooks
-            // but the message isn't used anywhere
-            // https://github.com/vercel/ai/blob/main/packages/ui-utils/src/call-chat-api.ts#L118
-            controller.enqueue(
-              encoder.encode('0:' + JSON.stringify('DONE') + '\n'),
-            );
-            controller.close();
+            onStreamFinish(reason ?? '', error);
+          } else {
+            timeout = setTimeout(() => {
+              results.push(FINAL_TIMEOUT_ERROR);
+              onStreamFinish('timeout', FINAL_TIMEOUT_ERROR.payload);
+            }, TIMEOUT_MILI_SECONDS);
           }
         }
       },