Keep a small server endpoint that always pulls fresh upstream data (using Lovable Secrets for credentials), and update your client hook to prefer that endpoint with short-polling + visibility/online listeners + a manual refresh trigger. Test in Lovable Preview, store credentials in Lovable Secrets, then Publish. If you need persistent background jobs or a WebSocket broker, export to GitHub and run that part outside Lovable.

Quick actionable Lovable prompt — create a server refresh endpoint and hook

Paste the following into Lovable chat. It tells Lovable to add an API route that always fetches fresh upstream data (no cache) and a client hook that keeps data current using polling, visibility change, online events, and a manual refresh.

// Create file src/server/api/refresh.ts
// This endpoint fetches fresh data from the upstream API using a secret and returns JSON with no-cache headers.

import type { RequestHandler } from 'express' // // if your project uses a different server framework, adapt to its API
export const handler: RequestHandler = async (req, res) => {
  // // use SECRET_UPSTREAM_API_KEY that we will set in Lovable Secrets UI
  const apiKey = process.env.SECRET_UPSTREAM_API_KEY
  try {
    const upstreamRes = await fetch('https://upstream.example.com/data', {
      // // force fresh upstream fetch
      cache: 'no-store',
      headers: {
        'Authorization': `Bearer ${apiKey}`,
        'Accept': 'application/json'
      }
    })
    const data = await upstreamRes.json()
    // // set headers so platform and clients don't cache this endpoint
    res.setHeader('Cache-Control', 'no-store, max-age=0')
    res.setHeader('Content-Type', 'application/json')
    res.status(upstreamRes.ok ? 200 : 502).json({ data, upstreamStatus: upstreamRes.status })
  } catch (err) {
    res.status(500).json({ error: 'fetch_failed', message: String(err) })
  }
}

// Create file src/hooks/useLiveData.tsx
// This hook calls /api/refresh, polls on an interval, refreshes when tab becomes visible or network comes back,
// and exposes manual refresh. Uses AbortController to avoid race conditions.

import { useEffect, useRef, useState, useCallback } from 'react'

export default function useLiveData() {
  const [data, setData] = useState(null)
  const [loading, setLoading] = useState(false)
  const abortRef = useRef(null)
  const intervalMs = Number(process.env.REACT_APP_REFRESH_INTERVAL_MS || 15000) // // configurable via Secrets/UI

  const fetchFresh = useCallback(async () => {
    if (abortRef.current) abortRef.current.abort()
    abortRef.current = new AbortController()
    setLoading(true)
    try {
      const res = await fetch('/api/refresh', { signal: abortRef.current.signal, cache: 'no-store' })
      if (!res.ok) throw new Error('bad_response')
      const json = await res.json()
      setData(json.data)
    } catch (e) {
      // // swallow or set error state as needed
      console.error('refresh failed', e)
    } finally {
      setLoading(false)
    }
  }, [])

  useEffect(() => {
    fetchFresh()
    const iv = setInterval(fetchFresh, intervalMs)

    const onVisibility = () => { if (document.visibilityState === 'visible') fetchFresh() }
    const onOnline = () => fetchFresh()

    document.addEventListener('visibilitychange', onVisibility)
    window.addEventListener('online', onOnline)

    return () => {
      clearInterval(iv)
      document.removeEventListener('visibilitychange', onVisibility)
      window.removeEventListener('online', onOnline)
      if (abortRef.current) abortRef.current.abort()
    }
  }, [fetchFresh, intervalMs])

  return { data, loading, refresh: fetchFresh }
}

Set required Secrets and test in Lovable

• Open Lovable Secrets UI and add SECRET_UPSTREAM_API_KEY with your upstream API key and REACT_APP_REFRESH_INTERVAL\_MS (e.g., 15000).
• Use Preview in Lovable to exercise the UI that uses useLiveData — verify data updates when you switch tabs, go offline/online, or click a refresh button.
• Publish when satisfied.

When something needs external infra

• If you need WebSockets or background workers that Lovable cannot host, paste this project to GitHub from Lovable (use GitHub sync/export), then set up the external service (outside Lovable — terminal/provider console required) and point your Lovable endpoint or client to that service.

Short answer: keep caches small and eager to revalidate, rely on client-side revalidation patterns (stale-while-revalidate, revalidate-on-focus/network), use push updates (Supabase realtime or webhooks) where possible, version cache keys and invalidate on mutations, store secrets in Lovable Secrets UI, and use Lovable Preview/Publish to validate freshness behavior — all implemented with Lovable-native edits, Preview, and Secrets (no terminal).

Actionable Lovable prompts to implement best practices

Copy each prompt below into Lovable chat. Each prompt tells Lovable exactly which files to create/update and what to test with Preview/Publish. I include code examples for files (these are instructions for Lovable to write/edit files).

• Create a small SWR-style client cache with revalidate-on-focus and network reconnect — create file src/lib/swrClient.tsx and add a simple revalidation wrapper used across the app:

// Create src/lib/swrClient.tsx
// A tiny SWR-like helper: get, set, subscribe, revalidate on focus/network reconnect

import React from "react";

type CacheEntry = { value: any; ts: number };
const cache = new Map<string, CacheEntry>();
const listeners = new Map<string, Set<() => void>>();

export function getCached(key: string) {
  return cache.get(key)?.value;
}

export function setCached(key: string, value: any) {
  cache.set(key, { value, ts: Date.now() });
  (listeners.get(key) || new Set()).forEach((cb) => cb());
}

export function subscribe(key: string, cb: () => void) {
  if (!listeners.has(key)) listeners.set(key, new Set());
  listeners.get(key)!.add(cb);
  return () => listeners.get(key)!.delete(cb);
}

// Revalidate on focus/network
window.addEventListener("visibilitychange", () => {
  if (document.visibilityState === "visible") {
    window.dispatchEvent(new Event("lovable_revalidate"));
  }
});
window.addEventListener("online", () => window.dispatchEvent(new Event("lovable_revalidate")));

• Create a reusable data fetcher that does stale-while-revalidate and invalidates on explicit updates — create src/components/DataFetcher.tsx and use the swrClient above:

// Create src/components/DataFetcher.tsx
// Usage: <DataFetcher key="/api/items" fetcher={fn} ttlMs={15000}>{data => <UI/>}</DataFetcher>

import React, { useEffect, useState } from "react";
import { getCached, setCached, subscribe } from "../lib/swrClient";

export default function DataFetcher({ cacheKey, fetcher, ttlMs = 15000, children }) {
  const [data, setData] = useState(() => getCached(cacheKey));
  useEffect(() => {
    let staleTimer: any;
    const handleUpdate = () => setData(getCached(cacheKey));
    const unsub = subscribe(cacheKey, handleUpdate);

    async function maybeFetch() {
      const entry = getCached(cacheKey);
      if (!entry || Date.now() - (entry?.ts || 0) > ttlMs) {
        const fresh = await fetcher();
        setCached(cacheKey, fresh);
      }
    }

    maybeFetch();
    const revalidateListener = () => maybeFetch();
    window.addEventListener("lovable_revalidate", revalidateListener);

    return () => {
      clearTimeout(staleTimer);
      unsub();
      window.removeEventListener("lovable_revalidate", revalidateListener);
    };
  }, [cacheKey, fetcher, ttlMs]);

  return children(data);
}

• Add optimistic update + cache invalidation helper for mutations — create src/lib/mutations.tsx so UI updates immediately and then triggers re-fetch/invalidation:

// Create src/lib/mutations.tsx
// optimisticUpdate(cacheKey, optimisticValue, mutationFn) -> applies optimistic value, calls mutationFn, then sets real value or rolls back

import { getCached, setCached } from "./swrClient";

export async function optimisticUpdate(cacheKey, optimisticValue, mutationFn) {
  const before = getCached(cacheKey);
  setCached(cacheKey, optimisticValue);
  try {
    const real = await mutationFn();
    setCached(cacheKey, real);
    return real;
  } catch (err) {
    setCached(cacheKey, before);
    throw err;
  }
}

• Enable push updates from Supabase (or any realtime) — add secrets and a realtime connector file — set secrets via Lovable Secrets UI: SUPABASE_URL and SUPABASE_ANON\_KEY. Then create src/lib/supabaseRealtime.ts (client-side) to wire events into cache keys.

// Create src/lib/supabaseRealtime.ts
// Use secrets set in Lovable Secrets UI. Wire incoming events to setCached(cacheKey, payload)

// // Fetch secrets in Lovable Preview/Publish environment automatically
const SUPABASE_URL = process.env.SUPABASE_URL;
const SUPABASE_ANON_KEY = process.env.SUPABASE_ANON_KEY;

import { createClient } from "@supabase/supabase-js";
import { setCached } from "./swrClient";

export function initSupabaseRealtime() {
  if (!SUPABASE_URL || !SUPABASE_ANON_KEY) return;
  const sb = createClient(SUPABASE_URL, SUPABASE_ANON_KEY);
  sb.channel("public:items").on("postgres_changes", { event: "*", schema: "public", table: "items" }, (payload) => {
    // // Map the payload to your cache key
    setCached("/api/items", payload.new ? payload.new : null);
  }).subscribe();
}

• Wrap app to initialize realtime and provide global defaults — update src/pages/\_app.tsx to call initSupabaseRealtime and ensure Preview tests will run the same code path:

// Update src/pages/_app.tsx in the top-level App component
import { useEffect } from "react";
import { initSupabaseRealtime } from "../lib/supabaseRealtime";

export default function App({ Component, pageProps }) {
  useEffect(() => {
    initSupabaseRealtime();
  }, []);
  return <Component {...pageProps} />;
}

Testing & deployment notes (Lovable-native)

• Set secrets — open Lovable Secrets UI, add SUPABASE_URL and SUPABASE_ANON\_KEY (exact names above).
• Preview — use Lovable Preview to exercise revalidate-on-focus (switch tabs) and realtime events (simulate via Supabase dashboard or webhook POSTs to your API endpoint).
• Publish — once verified, Publish from Lovable. If you need a server-side background job or CLI-only setup, use GitHub sync/export and deploy externally (this is outside Lovable and requires a terminal).