Admin SDK should support publishing topics to rooms

[uriva]

Problem

The admin SDK (@instantdb/admin) has a Rooms class that only exposes getPresence(). There is no way to publish topics from the server side.

The core SDK (@instantdb/core) supports joinRoom().publishTopic(), but the Reactor constructor has an isClient() guard that returns early when window is not defined, making it unusable in server environments (Node.js, Deno, etc.).

Use case

We're building a chat platform where a backend endpoint needs to broadcast ephemeral UI updates (spinner progress, status changes) to connected clients in a specific room. Topics are the perfect fit for this — fire-and-forget, no persistence needed. But since the admin SDK can't publish topics, we're forced to use persistent entities + reactive queries as a workaround, which adds unnecessary DB writes.

Desired behavior

import { init } from "@instantdb/admin";

const db = init({ appId, adminToken, schema });

// Publish a topic to a room (fire-and-forget to all connected clients)
await db.rooms.publishTopic("conversation", roomId, "uiUpdate", { elementId, percentage: 0.5 });

Current workaround

Using a persistent entity that clients read via useQuery, with manual cleanup of old records.

[stopachka]

This is a good issue @uriva ! I'll bring it to the team.

[actuallyepic]

++1! would be rly useful :)

we're currently hacking this by mocking a browser context with the @instantdb/core package so that we can publish presence from a CLI tool (but it is very brittle)

would love a first party solution

[uriva]

Update on this: upgrading to 0.22.174 made the workaround more fragile. The new PersistedObject in core now expects multiSet, getAllKeys, and removeItem on the storage class, so just stubbing getItem/setItem no longer cuts it. We also had to extend the indexedDB polyfill with getAllKeys, delete, objectStoreNames.contains, and createObjectStore.

Every core release risks breaking server-side core.init() further since it was never designed for this. Native db.rooms.publishTopic() on admin would let us drop all of it.