Read Arbitrary JSON Stores

MEDKit JSON stores are named, channel-scoped JSON documents. In @muxy/extensions-js@2.4.18, the public SDK exposes getJSONStore(key) for reads and emits json_store_update:<key> when a store changes.

The package declarations describe each stored value as smaller than 2 KB. Use regular state or configuration when those defined scopes fit your data.

Read a store

Initialize MEDKit and wait for it to load before reading data:

import Muxy from "@muxy/extensions-js";
Muxy.setup({ clientID: import.meta.env.VITE_MUXY_CLIENT_ID });
const medkit = new Muxy.SDK();
await medkit.loaded();

try {
  const basecamp = await medkit.getJSONStore("basecamp");
  console.log(basecamp);
} catch (error) {
  console.error("The basecamp store could not be read", error);
}

getJSONStore() rejects if the request fails or the key has no associated value. Omitting the key reads the default store.

React to updates

listen() returns a listener handle immediately; it does not return a promise. The event payload is not typed in 2.4.18, so re-read the store when correctness matters:

const handle = medkit.listen("json_store_update:basecamp", async () => {
  const basecamp = await medkit.getJSONStore("basecamp");
  renderBasecamp(basecamp);
});

window.addEventListener(
  "pagehide",
  () => medkit.unlisten(handle),
  { once: true },
);

Write limitation in 2.4.18

No public JSON-store writer

The published 2.4.18 SDK and StateClient types expose only getJSONStore(). Do not use the old pseudo-code set "key" to value or invent setJSONStore(). A writer requires a separately verified REST or trusted-backend contract and remains subject to SME review.