feat: add response compression middleware to reduce bandwidth (#928) (#935)

* feat: add response compression middleware for HTTP responses

Add compression middleware to Express server with SSE route exclusion
and 1KB threshold. Reduces bandwidth for non-streaming API responses
(history, sessions, files, static assets) by 60-80%.

Closes #928

* fix: harden proxy compression and proxy docs

---------

Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

packages/web/server/index.js

@@ -1,5 +1,6 @@
 import 'reflect-metadata';
 import express from 'express';
+import compression from 'compression';
 import path from 'path';
 import { spawn, spawnSync } from 'child_process';
 import fs from 'fs';
@@ -95,6 +96,27 @@ const TUNNEL_BOOTSTRAP_TTL_MAX_MS = 24 * 60 * 60 * 1000;
 const TUNNEL_SESSION_TTL_DEFAULT_MS = 8 * 60 * 60 * 1000;
 const TUNNEL_SESSION_TTL_MIN_MS = 5 * 60 * 1000;
 const TUNNEL_SESSION_TTL_MAX_MS = 30 * 24 * 60 * 60 * 1000;
+
+function headerIncludesEventStream(value) {
+  if (typeof value === 'string') {
+    return value.toLowerCase().includes('text/event-stream');
+  }
+
+  if (Array.isArray(value)) {
+    return value.some((entry) => typeof entry === 'string' && entry.toLowerCase().includes('text/event-stream'));
+  }
+
+  return false;
+}
+
+function shouldSkipCompression(req, res) {
+  if (headerIncludesEventStream(req.headers.accept)) {
+    return true;
+  }
+
+  return headerIncludesEventStream(res.getHeader('Content-Type'));
+}
+
 const OPENCHAMBER_VERSION = (() => {
   try {
     const packagePath = path.resolve(__dirname, '..', 'package.json');
@@ -970,6 +992,13 @@ async function main(options = {}) {
   const app = express();
   const serverStartedAt = new Date().toISOString();
   app.set('trust proxy', true);
+  app.use(compression({
+    filter: (req, res) => {
+      if (shouldSkipCompression(req, res)) return false;
+      return compression.filter(req, res);
+    },
+    threshold: 1024,
+  }));
   expressApp = app;
   server = http.createServer(app);