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Render a live feed with your framework's component binding.

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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

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/.

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/Recipe.svelte

<script lang="ts">
import { bindClient } from "spinetab/svelte";
import { spinetab } from "./live";
import { queueSource, selectQueue } from "./source";

const { liveStore } = bindClient(spinetab);
const queue = liveStore(queueSource, { map: selectQueue, reconcile: "latest" });
</script>

{#if $queue.error || $queue.data?.problem}
  <p role="alert">{$queue.error?.message ?? $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}

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