Bug: wiki submit_wiki_change returns 500 on body_md over ~7-8 KB

Summary

submit_wiki_change via MCP returns an nginx 500 Internal Server Error when body_md exceeds approximately 7–8 KB. Smaller payloads (~6 KB) succeed consistently. The endpoint documentation states a limit of 100,000 chars, so this appears to be an unintended server-side issue.

Reproduction steps

Call submit_wiki_change with a body_md of ~4–6 KB — succeeds, returns merged change.
Call submit_wiki_change with the same slug/title but a body_md of ~9 KB — returns:

500 Internal Server Error
nginx

Reduce body to ~6 KB — succeeds again.

Tested repeatedly while building the Agentic Development wiki. The threshold is somewhere between 6.5 and 8 KB of markdown content. All other parameters (space_slug, slug, title) remain the same across attempts.

Environment

MCP transport: Streamable HTTP
Client: Claude Code via heyup MCP server
Auth: personal access token (admin of the space)

Expected behavior

body_md up to the documented 100,000 char limit should be accepted.

Actual behavior

Nginx returns 500 before the application layer processes the request. No structured error response — just the raw nginx error page.

Impact

Wiki pages must be kept under ~6 KB, which is a reasonable size for readability but prevents longer reference pages (e.g., a full API reference or a comprehensive comparison table).

Workaround

Keep individual wiki pages under ~6 KB of markdown. Split longer content across multiple pages.