diff --git a/local-instance/proxy/nginx.conf b/local-instance/proxy/nginx.conf
index 22ce5eb..0066b5f 100644
--- a/local-instance/proxy/nginx.conf
+++ b/local-instance/proxy/nginx.conf
@@ -25,6 +25,17 @@ server {
 	proxy_read_timeout 300s;
 	proxy_send_timeout 300s;
 
+	# The legacy client sets several large cookies at once (jwt plus the
+	# Etherpad session it requests on every topic page), which overflows
+	# nginx's default 4k header buffer: the upstream answers 200 and the proxy
+	# still returns 502 with "upstream sent too big header". Topic pages are
+	# the visible casualty, and because the MCP server's topic-page scrape
+	# degrades to an empty list by design, the ids it recovers just silently
+	# vanish rather than erroring.
+	proxy_buffer_size 32k;
+	proxy_buffers 8 32k;
+	proxy_busy_buffers_size 64k;
+
 	# version-aggregator-svc upstream; /serverversion and /nuxtversion are the
 	# real per-app endpoints and are routed below.
 	location = /version {
diff --git a/local-instance/scripts/gen-proxy-conf.py b/local-instance/scripts/gen-proxy-conf.py
index 1544a2a..ff8a246 100644
--- a/local-instance/scripts/gen-proxy-conf.py
+++ b/local-instance/scripts/gen-proxy-conf.py
@@ -76,6 +76,17 @@ server {
 	proxy_read_timeout 300s;
 	proxy_send_timeout 300s;
 
+	# The legacy client sets several large cookies at once (jwt plus the
+	# Etherpad session it requests on every topic page), which overflows
+	# nginx's default 4k header buffer: the upstream answers 200 and the proxy
+	# still returns 502 with "upstream sent too big header". Topic pages are
+	# the visible casualty, and because the MCP server's topic-page scrape
+	# degrades to an empty list by design, the ids it recovers just silently
+	# vanish rather than erroring.
+	proxy_buffer_size 32k;
+	proxy_buffers 8 32k;
+	proxy_busy_buffers_size 64k;
+
 	# version-aggregator-svc upstream; /serverversion and /nuxtversion are the
 	# real per-app endpoints and are routed below.
 	location = /version {