Persistent State

Key-value storage is optional and lives in your server code, not in @farcaster/snap itself.

For coding agents: use @farcaster/snap-turso. It exports a DataStore with:

await store.get(key) — returns a JSON-serializable value or null if the key is missing.
await store.set(key, value) — writes the value (overwrites an existing key).

Create a single store when the process starts (module scope), then close over it inside your SnapFunction.

import type { SnapFunction } from "@farcaster/snap";
import { createTursoDataStore } from "@farcaster/snap-turso";

const store = createTursoDataStore();

const snap: SnapFunction = async (ctx) => {
  const visits = ((await store.get("visits")) as number) ?? 0;
  await store.set("visits", visits + 1);
  return {
    version: "1.0",
    ui: {
      root: "page",
      elements: {
        page: { type: "stack", props: {}, children: ["count"] },
        count: {
          type: "text",
          props: { content: `Visits: ${visits + 1}` },
        },
      },
    },
  };
};

createTursoDataStore() uses an in-memory map for local development and testing.

Full wiring example lives in the repo template — start from template/src/index.ts.