Choosing a backend

Choose persistence and attachment storage independently, with explicit factories bound to verified identity.

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

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.

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.