@myatthirikhin/chat-supabase

A chat backend on Postgres, RLS, Realtime and Storage — the adapter and the schema.

pnpm add @myatthirikhin/chat-core @myatthirikhin/chat-supabase @supabase/supabase-js

Then apply the SQL. → SETUP.md — installing the package is half the job; the other half is a database.

import { ChatClient } from '@myatthirikhin/chat-core';
import { createSupabaseChatProvider } from '@myatthirikhin/chat-supabase';

const chat = new ChatClient({ provider: createSupabaseChatProvider(supabase) });
await chat.connect({ id: userId, name: 'Ana' });

No tokenProvider: the Supabase session already in your client is the credential. There is no token endpoint to deploy and no secret to rotate — the main practical difference from Stream and Sendbird.

What ships here

| | | |---|---| | src/ | the IMessagingProvider implementation | | sql/ | three migrations: schema + RLS + RPCs, Realtime, Storage | | functions/push-fanout/ | an Edge Function that pushes through Expo's service |

Design notes

• Keyset pagination on (conversation_id, id desc) — never OFFSET, which is O(offset) and wrong under the concurrent inserts chat has by definition.
• Read state is a monotonic watermark, not a receipts table. Receipts cost messages × members rows to buy a per-message timestamp no chat UI displays.
• Soft delete only. A real DELETE emits a Realtime event whose old-record payload is not RLS-filtered — a security decision, not a style one.
• Three Realtime channels per client, forever, regardless of conversation count. Realtime caps channels at 100 per connection, so one subscription per conversation breaks at 100 conversations.
• One SECURITY DEFINER helper breaks the members↔messages RLS recursion (42P17).

Scaling

The first wall is concurrent connections (500 on Pro with the spend cap on), not throughput. Then messages/sec, which counts after fan-out. postgres_changes doesn't get faster on a bigger instance; past ~3,000 concurrent subscribers, switch to broadcast-from-database — the SQL is at the bottom of sql/0002_chat_realtime.sql.

License

MIT