Function rateLimitedFetch

background.js:219–258

(url, options = {})

const rateLimitState = new Map();

async function rateLimitedFetch(url, options = {}) {
  const settings = await getSettings();
  const domain = new URL(url).hostname;

  if (!rateLimitState.has(domain)) {
    rateLimitState.set(domain, { delay: settings.baseDelay, lastRequest: 0 });
  }

  const state = rateLimitState.get(domain);
  const now = Date.now();
  const timeSince = now - state.lastRequest;

  if (timeSince < state.delay) {
    await new Promise(r => setTimeout(r, state.delay - timeSince));
  }

  state.lastRequest = Date.now();

  try {
    const response = await fetch(url, { ...options, signal: AbortSignal.timeout(15000) });

    if ([429, 503, 502].includes(response.status)) {
      state.delay = Math.min(state.delay * 2, 10000);
      const retryAfter = response.headers.get('Retry-After');
      if (retryAfter) {
        await new Promise(r => setTimeout(r, parseInt(retryAfter) * 1000));
      }
      throw new Error(`Rate limited: ${response.status}`);
    }

    // Recover delay on success
    state.delay = Math.max(state.delay * 0.9, settings.baseDelay);
    return response;
  } catch (error) {
    if (error.name === 'TimeoutError') {
      state.delay = Math.min(state.delay * 1.5, 10000);
    }
    throw error;
  }
}

// ============================================================================
// CONTENT FILTERING & COMPARISON