Choosing a backend

createChatHandler separates conversation persistence (ChatStore) from attachment storage (StorageAdapter). Both are factories called after authentication with the verified userId.

code

type ChatStoreFactory = (userId: string) => ChatStore;
type StorageAdapterFactory = (userId: string) => StorageAdapter;

Options

Need	Factory
Self-hosted Postgres conversations	`createDrizzleChatStore()`
Private Supabase attachments	`createSupabaseStorage()`
Hosted conversations	`createHostedChatStore({ apiKey })`
Hosted attachments	`createHostedStorage({ apiKey })`
Custom database/object store	Your own user-bound factory

Persistence is currently required; there is no silent default store. Storage is optional and uploads are disabled when it is absent.

code

export const { GET, POST, DELETE } = createChatHandler({
  getUserId: getChatUserId,
  model,
  store: createDrizzleChatStore(),
  storage: createSupabaseStorage(),
});

Mix the axes deliberately: Drizzle plus Supabase, hosted store plus custom storage, or fully custom implementations. All custom stores/adapters must uphold the ownership and private-attachment invariants.

Drizzle / Postgres

Current chat schema and connection options.

Supabase storage

Private bucket and signed URLs.

Hosted

Server-side hosted clients and config fallbacks.

Custom

Implement the user-bound contracts.