ai-persistence/server

Server Chat Persistence

Builds on ai-persistence. Package: @tanstack/ai-persistence.

withPersistence(persistence) is a ChatMiddleware that writes chat state to a backend: messages, runs, interrupts (optional metadata). It does not mutate the chunk stream and does not replace delivery durability.

Setup

import {
  chat,
  chatParamsFromRequest,
  toServerSentEventsResponse,
} from '@tanstack/ai'
import { openaiText } from '@tanstack/ai-openai'
import { withPersistence } from '@tanstack/ai-persistence'
// Your adapter — see ai-persistence/stores.
import { persistence } from './persistence'

export async function POST(request: Request) {
  const params = await chatParamsFromRequest(request)
  const stream = chat({
    adapter: openaiText('gpt-5.5'),
    messages: params.messages,
    threadId: params.threadId,
    runId: params.runId,
    ...(params.resume ? { resume: params.resume } : {}),
    middleware: [withPersistence(persistence)],
  })
  return toServerSentEventsResponse(stream)
}

Always pass threadId and runId from the client (via chatParamsFromRequest / body helpers). Forward resume when the client resolves pending interrupts.

For dev and tests, memoryPersistence() from @tanstack/ai-persistence is a drop-in backend that implements all four stores in process.

What each store does

Named shapes: ChatTranscriptPersistence (floor), ChatPersistence (all four). Annotate your factory with one of these, not with bare AIPersistence — the unparameterized type is the all-optional bag, and withPersistence rejects it because stores.messages is possibly undefined.