A topic page makes the legacy client set several large cookies at once —
jwt plus the Etherpad session it asks for — which overflows nginx's default
4k header buffer. The upstream answered 200 and the proxy still returned 502
with "upstream sent too big header".
It went unnoticed because the MCP server's topic-page scrape degrades to an
empty list by design: the task ids it recovers from that page silently
vanished instead of failing. Changed in the generator and in the generated
config.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
a3b17a680c