1256664361
The app needs a reliable "is this message mine?" signal. senderActorId worked only with a lazily-learned actorId, which Supabase token-refresh wipes. senderId is the sender's externalId (email/username) — always present and comparable to the session user — so message alignment is deterministic. Verified: senderId round-trips = email. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>