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Neon Realtime

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  • Data and AI
  • Apache-2.0
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From the author

Neon Realtime makes any SQL query live. Build realtime, reactive apps and agents on Lakebase Postgres with live SQL queries and reactivity primitives. Use when app UI or agent state must update live from database rows (dashboards, feeds, collaboration, multi-user or multi-device sync), for optimistic mutations, or to replace polling or other realtime sync systems. Triggers include "live query", "subscribe", "sync engine", "useLiveQuery", "TanStack DB", "optimistic updates", "@neon/realtime". For push that doesn't come from database rows (presence, typing, LLM streams), use neon-functions.
— the description by Neon

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

Neon Realtime enables developers to create reactive applications and agents by transforming static SQL queries into live, streaming data sources. By utilizing a combination of server-side query sealing and client-side reactivity primitives, it allows UI components and agent states to update automatically as database rows change. This approach eliminates the need for manual polling or complex custom synchronization logic, providing a type-safe, performant way to keep frontends and backend services in sync with the underlying Postgres database.

What it does

  • Converts standard SQL queries into live, reactive data streams.
  • Provides secure query sealing to prevent unauthorized data access or modification.
  • Supports optimistic UI updates to ensure immediate user feedback during data mutations.
  • Integrates with popular ORMs like Drizzle and Kysely for seamless development.
  • Offers React-specific hooks for binding live database state to UI components.
  • Enables efficient synchronization for dashboards, feeds, and multi-user collaboration.

When to use it

  • When building dashboards or feeds that require live data updates.
  • When implementing collaborative features that need multi-user or multi-device synchronization.
  • When you want to replace inefficient polling mechanisms with a push-based sync system.
  • When developing optimistic UI patterns to improve perceived application performance.
  • When building AI agents that need to react to real-time changes in database state.

Advantages

  • Reduces network overhead by replacing polling with WebSocket-based streaming.
  • Simplifies state management by keeping UI in sync with database transactions.
  • Enhances user experience through instant, optimistic UI updates.
  • Maintains security by authorizing and sealing queries on the backend.
  • Works with existing SQL knowledge and familiar ORM workflows.

Usage examples

“How do I make a list of messages in my chat app update in real-time?”
You define a sealed SQL query on your backend that selects messages for a specific channel, then use the useLiveQuery hook in your React frontend to subscribe to that query and automatically update the message list as new rows are inserted.
“How can I implement optimistic updates for a user action?”
You perform the write operation through your backend, return the transaction ID, and use the awaitTxId utility on the client to wait for the database confirmation while immediately updating the local UI state.

Install

  1. Download the skill as a ZIP:

    https://mp-staging.autogineer.com/agent-skills/neondatabase/neon-realtime/download
  2. Unzip it into the cross-client skills folder of your project:

    mkdir -p .agents/skills && unzip neon-realtime.zip -d .agents/skills

Documentation by Neon

FIRST: Use the parent neon skill for a Neon overview, getting started with Neon, Neon development best practices, and more.

If the neon skill is not installed, fetch it from https://neon.com/docs/ai/skills/neon/SKILL.md or install it with:

neon skills -s neon -y

Neon Realtime

Neon's Realtime makes any SQL query live. Subscribe in realtime to your Lakebase Postgres database. Develop apps and agents with end-to-end reactivity using type-safe live queries and optimistic mutations.

Realtime is new and in beta, so its APIs aren't in your training data. Start from the core pattern below, and read each section's reference file before writing that code.

How It Works

Realtime's layers compose: a live query engine inside Postgres, the Live SQL API (a WebSocket API), lower-level client SDKs (seal(), subscribe()), and reactivity primitives such as useLiveQuery.

  1. In trusted backend code, define a live query (any read-only SQL, including joins, aggregates, ordering and limits), seal it with NEON_REALTIME_SECRET and expose it from an authenticated endpoint or server function. The client can't read or change a sealed query's SQL or parameters.

  2. The client subscribes with the sealed query. It receives the full initial result, then each committed transaction's changes as one batch. Results stay consistent, but delivery of every change event isn't guaranteed.

  3. Writes go through your own API, which returns each write's txid for awaitTxId().

Core Pattern

The guides' chat app, with messages authorized through channel_members. The backend seals the query and returns each write's txid:

import { createRealtime, rawSql } from "@neon/realtime/server"
import { drizzleAdapter } from "@neon/realtime-drizzle"
import { and, desc, eq, getTableColumns, sql } from "drizzle-orm"
import { Hono } from "hono"
import { HTTPException } from "hono/http-exception"
import { requireUser } from "./auth"
import { db } from "./db"
import { channelMembers, messages, type Message } from "./schema"

export const realtime = createRealtime({ secret: process.env.NEON_REALTIME_SECRET!, db: "neondb", adapter: drizzleAdapter() })

// Each selected key must match its column name
export function messagesQuery(userId: string, channelId: number) {
  return db
    .select(getTableColumns(messages)).from(messages)
    .innerJoin(channelMembers, eq(channelMembers.channel_id, messages.channel_id))
    .where(and(eq(channelMembers.user_id, userId), eq(messages.channel_id, channelId)))
    .orderBy(desc(messages.created_at))
    .limit(50)
}

// Or raw SQL
const rawMessagesQuery = (userId: string, channelId: number) => rawSql<Message>(
    `SELECT messages.author_id, messages.body, messages.channel_id, messages.created_at, messages.id FROM messages
     INNER JOIN channel_members ON channel_members.channel_id = messages.channel_id WHERE channel_members.user_id = $1 AND messages.channel_id = $2 ORDER BY messages.created_at DESC LIMIT 50`,
    [userId, channelId]
  )

// The id of the transaction that made the change, read in the write's own RETURNING
const txid = sql<string>`pg_current_xact_id()::text`

const app = new Hono()
  .post("/api/v1/messages/live", async (c) => {
    const user = await requireUser(c)
    const { channelId } = await c.req.json<{ channelId: number }>() // validate input
    return c.json(await realtime.seal({ query: messagesQuery(user.id, channelId) }))
  })
  .post("/api/v1/messages", async (c) => {
    const user = await requireUser(c)
    const { id, channelId, body } = await c.req.json<{ id: string; channelId: number; body: string }>() // validate input
    // One statement. The membership row supplies channel_id and author_id, so only a member's message is inserted.
    // List every column in table order, alias each sql field, and cast untyped params (they resolve to text)
    const [sent] = await db.insert(messages).select(
      db.select({
          id: sql`${id}::uuid`.as("id"), channel_id: channelMembers.channel_id, author_id: channelMembers.user_id,
          body: sql`${body}`.as("body"), created_at: sql`now()`.as("created_at"),
        })
        .from(channelMembers)
        .where(and(eq(channelMembers.channel_id, channelId), eq(channelMembers.user_id, user.id)))
    ).returning({ txid })
    if (!sent) throw new HTTPException(403, { message: "Not a member of this channel" })
    return c.json({ kind: "committed", txid: sent.txid })
  })

The React frontend subscribes and sends optimistic messages:

import { createRealtimeClient, type SealedLiveQuery } from "@neon/realtime/client"
import { drizzleParsers } from "@neon/realtime-drizzle/client"
import { useLiveQuery } from "@neon/realtime-react"
import { startTransition, useCallback, useOptimistic } from "react"
import type { Message } from "../backend/schema"
import { fetchSealedMessages, sendMessage } from "./api"

// One client per app, because subscriptions share its connection. Wrap the app in <RealtimeProvider client={client}>
export const client = createRealtimeClient({ url: import.meta.env.VITE_NEON_REALTIME_URL, parsers: { ...drizzleParsers } })

const NO_MESSAGES: readonly Message[] = []
type Props = { sealedQuery: SealedLiveQuery<Message>; channelId: number; userId: string }

export function Messages({ sealedQuery, channelId, userId }: Props) {
  const refreshQuery = useCallback(() => fetchSealedMessages(channelId), [channelId])
  const { data, status, error, utils } = useLiveQuery(sealedQuery, { refreshQuery })
  // Once the sent message syncs, show only the synced row
  const [messages, addOptimistic] = useOptimistic(data ?? NO_MESSAGES, (current, message: Message) =>
    current.some(({ id }) => id === message.id) ? current : [message, ...current]
  )

  function send(body: string) {
    // The server sets author and timestamp but keeps this id
    const message = { id: crypto.randomUUID(), channel_id: channelId, author_id: userId, body, created_at: new Date() }
    startTransition(async () => {
      addOptimistic(message)
      try {
        const result = await sendMessage(message) // maps channel_id to channelId
        if (result.kind === "committed") await utils.awaitTxId(result.txid, 10_000)
      } catch { /* show "Couldn't confirm the change" */ }
    })
  }

  if (status === "error") return <p role="alert">Live updates stopped: {error.message}</p>
  if (data === undefined) return <p>Loading messages</p>
  return (
    <form action={(form) => send(String(form.get("body")))}>
      <input name="body" required />
      <ul>{messages.map((message) => <li key={message.id}>{message.body}</li>)}</ul>
    </form>
  )
}

Choose the Stack

A live query replaces fetching app data from an API or another sync system. Reuse existing query code, and use the highest layer that fits rather than wiring changes into app state by hand.

UseFor
drizzleAdapter() from @neon/realtime-drizzle, or kyselyAdapter() from @neon/realtime-kyselyQueries written in Drizzle or Kysely
rawSql from @neon/realtime/serverAny other ORM, or none
useLiveQuery from @neon/realtime-reactReact. Binds one sealed query to a component's state
realtimeCollectionOptions from @neon/realtime-tanstackMany views over the same data, or an app on TanStack DB. Oversync one broader query into a collection, then derive local live queries from it
client.subscribe() from @neon/realtime/clientOther frameworks
realtime.subscribe() from @neon/realtime/serverAgents and workers, in trusted backend code

Migrating from Electric: Realtime is a drop-in replacement for Electric's role in your stack. Live SQL queries replace shapes, and realtimeCollectionOptions() replaces electricCollectionOptions().

Setup

  • New app: neon bootstrap my-app --template realtime-react, then neon deploy in my-app.

  • Enable it on the linked branch with neon realtime enable --allowed-origin <app origin>, or declare preview: { realtime: true } in neon.ts (neon config add realtime) and run neon deploy. Child branches inherit it. It's unavailable on Claimable projects until claimed, or outside the supported regions.

  • Tables need a stable replica identity; a primary key is enough. Leave row-level security off on every table a live query reads: Realtime rejects those subscriptions with unsupported query: row security. For per-user data, authorize in the sealed query instead (see below).

  • Environment: neon env pull --service postgres --service realtime writes DATABASE_URL, NEON_REALTIME_URL and NEON_REALTIME_SECRET. Expose only the URL to the browser, under your framework's public prefix (like VITE_). url options take NEON_REALTIME_URL; db takes the database name from DATABASE_URL.

  • Install @neon/realtime and the packages chosen above. Use these SDKs, not the still-evolving WebSocket protocol.

Define and Seal Queries

Read references/queries.md before writing query or sealing code, including Kysely and server functions.

  • Read-only and deterministic. A raw query is a single SELECT with no ; and $1 placeholders. It can't call now() or gen_random_uuid(), so pass such values as parameters, wrapping every value except strings, numbers, booleans, bigints and null in a pgParam helper (pgParam.timestamptz(date)).

  • Authorize in the query. Check the session before sealing, and join through your membership tables so revoked access drops out. Any web framework auth works, including Managed Better Auth, but not RLS yet. See Authorization.

  • A sealed query is a bearer token. Keep it out of URLs, logs and persistent storage, and never fill its parameters from unchecked input.

  • Check a query before wiring it in: neon realtime subscribe "SELECT ..." prints the initial result, then each transaction's changes, until you stop it. With --output json, each change prints a full snapshot. Set debugMode on createRealtime for full database errors (development only).

  • Sealed queries expire. Pass refreshQuery to the bindings or call renew(), sealing the same query and parameters, or the subscription errors. New parameters need a new sealed query and subscription. In Next.js, renew from a Route Handler, because server actions run one at a time.

Subscribe

Read references/reactivity.md before writing React or TanStack DB code. Read references/subscribing.md before subscribing directly with client.subscribe(sealed) (getSnapshot, onChange, onStateChange), or from agents and workers, which add url to createRealtime and await realtime.subscribe(query) to seal in-process.

  • One database per client. The first sealed query binds the connection to its db.

  • Select a stable, unique key for every row and key rows by it, including TanStack DB's getKey: usually the primary key, the grouped columns for aggregates, or the combined keys for joins that repeat a row. Never use rowId, which every rows update invalidates.

  • error is final, even after renew(). Fetch a fresh sealed query and subscribe again, with a new client if the connection failed. Watch onStateChange on direct subscriptions; useLiveQuery() reports errors through status, not by throwing or suspending.

  • When the session changes, leave with a full page load. It drops the Realtime client, any TanStack DbClient and the previous user's rows. The hook retries a failed renewal every second, so stop renewing once one fails as signed out. Check on every renewal and write that the session's user is the one the page was loaded for, or a write from the old page lands in the new user's account. See When the session changes.

Optimistic Writes

Realtime has no write path, so writes keep your backend's usual auth. Read references/mutations.md before writing mutations, for each layer.

  • Return the txid from the write itself: .returning({ txid: sql<string>`pg_current_xact_id()::text` }), in one round trip on any Postgres driver. Write a batch in one statement, so there's one txid. Never open db.transaction() just to select pg_current_xact_id(): that's four round trips holding a pooled connection. When a write genuinely needs several statements, put the txid in the RETURNING of a write that always changes a row.

  • Always pass awaitTxId() a timeout: it keeps waiting through reconnects and renewals, and never settles if the txid doesn't reach the query.

  • A write that changes no rows has no txid, so skip awaitTxId() and let the optimistic state drop.

Server-Side Rendering

Read references/ssr.md before rendering live queries on the server, for Next.js and TanStack Start.

  • Create the client in a useState initializer rather than at module level, render initialData as live rows without a loading state, and never share a TanStack DbClient between requests.

  • Keep row shapes identical on both sides. JSON.stringify turns dates into strings, and int8 and numeric arrive as strings.

More Docs

TaskPage
Beta scope, regions, pricing, FAQ, other systemsOverview
Architecture and consistencyHow it works
A first live queryQuickstart
Every SDK exportTypeScript SDK reference
Full-stack apps with auth and SSRNext.js, TanStack
Live agent workflowsMastra
ORM adaptersDrizzle, Kysely

Files

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Requirements and compatibility

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

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Published by
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neondatabase/agent-skills · skills/neon-realtime · commit 2b0e2b6
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