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Feed shared updates into your existing query cache.

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Server-sent events · SvelteKit

Before you start

Start with an existing SvelteKit app. Keep its renderer, routes and plugins. These files add one live view; Spinetab does not create your API.

Your endpoint supplies complete { "open": 12 } values: JSON in each data: field of /api/queue/events, served as text/event-stream.

The examples use same-origin URLs and declare anonymous: true: no token is supplied, although cookies still flow. For a separate API origin, use its URL and configure CORS or your application's proxy. For private data, add credentials and user scopes; never put a secret in these files.

1. Install

pnpm add spinetab @tanstack/query-core@^5.104.0 @tanstack/svelte-query@^6.3.0

Keep your framework's existing dependencies. See compatible versions if upgrading an older app.

2. Configure your app

Merge this addition into your configuration; preserve existing plugins and options. Restart the dev server afterwards. The plugin bundles the worker and discovers the adapters imported below.

vite.config.ts

import { sveltekit } from "@sveltejs/kit/vite";
import { spinetab } from "spinetab/vite";
import { defineConfig } from "vite";

export default defineConfig({ plugins: [sveltekit(), spinetab()] });

3. Connect and render

Save these files together in src/lib/recipe/.

The provider owns a fresh QueryClient. If your app already has a provider, render Queue beneath it instead of creating another one. The query uses skipToken to read live cache updates without fetching a competing snapshot. The bridge uses that same client's ["queue"] key.

reconcile: "latest" fits this full-state contract: the next complete event restores the displayed value after a gap. Use a refresh/merge policy for deltas or partial GraphQL results. Reconnecting alone does not reconstruct missed state.

src/lib/recipe/live.ts

import { createSpinetab } from "spinetab";

export const spinetab = createSpinetab({ anonymous: true });

src/lib/recipe/queue-types.ts

export type Queue = { open: number };
export type QueueView = { open?: number; problem?: string };

src/lib/recipe/source.ts

import { sse } from "spinetab/sse";
import type { Queue, QueueView } from "./queue-types";

export const queueSource = sse<Queue>("/api/queue/events");
export const selectQueue = (queue: Queue): QueueView => queue;

src/lib/recipe/feed.ts

import type { QueryClient } from "@tanstack/query-core";
import { bindQuery } from "spinetab/tanstack-query";
import { spinetab } from "./live";
import { queueSource, selectQueue } from "./source";

export function startQueue(
  queryClient: QueryClient,
  onError: (message: string) => void,
) {
  return bindQuery(spinetab, queueSource, {
    queryClient,
    queryKey: ["queue"],
    map: selectQueue,
    reconcile: "latest",
    onError: (error) => onError(error.message),
    onEvent: () => onError(""),
  });
}

src/lib/recipe/Queue.svelte

<script lang="ts">
import { createQuery, skipToken, useQueryClient } from "@tanstack/svelte-query";
import { onMount } from "svelte";
import { startQueue } from "./feed";
import type { QueueView } from "./queue-types";

const client = useQueryClient();
const queue = createQuery<QueueView>(() => ({
  queryKey: ["queue"],
  queryFn: skipToken,
}));
let error = $state("");
onMount(() => {
  const binding = startQueue(client, (message) => {
    error = message;
  });
  return () => binding.unsubscribe();
});
</script>

{#if error || queue.data?.problem}
  <p role="alert">{error || queue.data?.problem}</p>
{:else if queue.data?.open === undefined}
  <p role="status">Loading queue…</p>
{:else}
  <p><output>{queue.data.open}</output> open</p>
{/if}

src/lib/recipe/Recipe.svelte

<script lang="ts">
import { QueryClient, QueryClientProvider } from "@tanstack/svelte-query";
import Queue from "./Queue.svelte";

const client = new QueryClient();
</script>

<QueryClientProvider {client}><Queue /></QueryClientProvider>

4. Mount the view

src/routes/queue/+page.svelte

<script lang="ts">
import Recipe from "../../lib/recipe/Recipe.svelte";
</script>
<main><Recipe /></main>

Keep your existing SvelteKit deployment adapter. Component lifecycle keeps live work out of server rendering; do not disable SSR or subscribe in a server load function.

Check the result

Open /queue in two tabs of the same browser profile. Both should show advancing queue values. Matching subscriptions share upstream work when SharedWorker is available; fallback runs independently in each tab. Remove one view and the other should keep updating. Removing the last view releases its subscription; connection closure can follow the adapter's idle delay.

API options and advanced recovery · Authentication