fix: strip accept-encoding + install brotli to prevent 502 on multi-port proxy

proxy.py

@@ -562,8 +562,12 @@ async def http_proxy(request, port, upstream_base, path, keep_prefix=False):
             return web.Response(status=status, headers=headers, body=body)
 
     # Forward headers
+    # Strip `accept-encoding` so the upstream sends an uncompressed body
+    # — otherwise apps that reply with brotli (`br`) crash aiohttp.read()
+    # (no brotli decoder installed) and the body is unreadable. localhost
+    # bandwidth is free, so we always request identity encoding.
     skip = {"host", "connection", "keep-alive", "transfer-encoding",
-            "upgrade", "cookie", "content-length"}
+            "upgrade", "cookie", "content-length", "accept-encoding"}
     headers = {k: v for k, v in request.headers.items() if k.lower() not in skip}
 
     body = await request.read()

requirements.txt

@@ -2,3 +2,4 @@ jupyterlab==4.5.7
 tornado==6.5.5
 ipywidgets==8.1.8
 aiohttp==3.11.16
+brotli==1.1.0