THE disappearing-messages root cause (found via THREAD.length=300 vs 351 on server).
messages.thread and threadByConversation did 'ORDER BY created_at ASC LIMIT 300' —
the oldest 300. Once a DM/group passed 300 messages, every newer message was silently
dropped from the fetch, so anything sent after that point 'disappeared' (persisted
server-side, never returned to the client). Now: inner 'ORDER BY created_at DESC LIMIT'
takes the NEWEST N, outer ASC presents them oldest-first. Cap raised 300 -> 500.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>