GET /messages/ accepts offset with stable created_at,id ordering; C-25 pages
every reply per counterpart, dedups by message id and warns explicitly when
collection is incomplete instead of capping at 200.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 671493@bnt-lap001
Assistant-Session: 60d7b11f-78f9-4731-9367-918511b2762d
