✨ feat: Implement Resumable Generation Jobs with SSE Support

- Introduced GenerationJobManager to handle resumable LLM generation jobs independently of HTTP connections.
- Added support for subscribing to ongoing generation jobs via SSE, allowing clients to reconnect and receive updates without losing progress.
- Enhanced existing agent controllers and routes to integrate resumable functionality, including job creation, completion, and error handling.
- Updated client-side hooks to manage adaptive SSE streams, switching between standard and resumable modes based on user settings.
- Added UI components and settings for enabling/disabling resumable streams, improving user experience during unstable connections.

api/server/routes/agents/chat.js

@@ -1,9 +1,11 @@
 const express = require('express');
-const { generateCheckAccess, skipAgentCheck } = require('@librechat/api');
+const { generateCheckAccess, skipAgentCheck, GenerationJobManager } = require('@librechat/api');
+const { logger } = require('@librechat/data-schemas');
 const { PermissionTypes, Permissions, PermissionBits } = require('librechat-data-provider');
 const {
   setHeaders,
   moderateText,
+  requireJwtAuth,
   // validateModel,
   validateConvoAccess,
   buildEndpointOption,
@@ -28,6 +30,97 @@ const checkAgentResourceAccess = canAccessAgentFromBody({
   requiredPermission: PermissionBits.VIEW,
 });
 
+/**
+ * @route GET /stream/:streamId
+ * @desc Subscribe to an ongoing generation job's SSE stream
+ * @access Private
+ */
+router.get('/stream/:streamId', requireJwtAuth, (req, res) => {
+  const { streamId } = req.params;
+
+  const job = GenerationJobManager.getJob(streamId);
+  if (!job) {
+    return res.status(404).json({
+      error: 'Stream not found',
+      message: 'The generation job does not exist or has expired.',
+    });
+  }
+
+  // Disable compression for SSE
+  res.setHeader('Content-Encoding', 'identity');
+  res.setHeader('Content-Type', 'text/event-stream');
+  res.setHeader('Cache-Control', 'no-cache, no-transform');
+  res.setHeader('Connection', 'keep-alive');
+  res.setHeader('X-Accel-Buffering', 'no');
+  res.flushHeaders();
+
+  logger.debug(`[AgentStream] Client subscribed to ${streamId}`);
+
+  const unsubscribe = GenerationJobManager.subscribe(
+    streamId,
+    (event) => {
+      if (!res.writableEnded) {
+        res.write(`event: message\ndata: ${JSON.stringify(event)}\n\n`);
+        if (typeof res.flush === 'function') {
+          res.flush();
+        }
+      }
+    },
+    (event) => {
+      if (!res.writableEnded) {
+        res.write(`event: message\ndata: ${JSON.stringify(event)}\n\n`);
+        if (typeof res.flush === 'function') {
+          res.flush();
+        }
+        res.end();
+      }
+    },
+    (error) => {
+      if (!res.writableEnded) {
+        res.write(`event: error\ndata: ${JSON.stringify({ error })}\n\n`);
+        if (typeof res.flush === 'function') {
+          res.flush();
+        }
+        res.end();
+      }
+    },
+  );
+
+  if (!unsubscribe) {
+    return res.status(404).json({ error: 'Failed to subscribe to stream' });
+  }
+
+  if (job.status === 'complete' || job.status === 'error' || job.status === 'aborted') {
+    res.write(`event: message\ndata: ${JSON.stringify({ final: true, status: job.status })}\n\n`);
+    res.end();
+    return;
+  }
+
+  req.on('close', () => {
+    logger.debug(`[AgentStream] Client disconnected from ${streamId}`);
+    unsubscribe();
+  });
+});
+
+/**
+ * @route POST /abort
+ * @desc Abort an ongoing generation job
+ * @access Private
+ */
+router.post('/abort', (req, res) => {
+  const { streamId, abortKey } = req.body;
+
+  const jobStreamId = streamId || abortKey?.split(':')?.[0];
+
+  if (jobStreamId && GenerationJobManager.hasJob(jobStreamId)) {
+    GenerationJobManager.abortJob(jobStreamId);
+    logger.debug(`[AgentStream] Job aborted: ${jobStreamId}`);
+    return res.json({ success: true, aborted: jobStreamId });
+  }
+
+  res.status(404).json({ error: 'Job not found' });
+});
+
 router.use(checkAgentAccess);
 router.use(checkAgentResourceAccess);
 router.use(validateConvoAccess);