Exact code. No black boxes.

// Bollinger Bands — mean ± (multiplier × std dev)
function calculateBollingerBands(prices, period, multiplier) {
  const slice = prices.slice(0, period);
  const mean = slice.reduce((a, b) => a + b, 0) / period;
  const variance = slice.reduce((s, p) => s + (p - mean) ** 2, 0) / period;
  const stdDev = Math.sqrt(variance);
  return {
    upper: mean + multiplier * stdDev,
    middle: mean,
    lower: mean - multiplier * stdDev
  };
}

// Signal generator — dual confirmation required to enter
function bollingerRsiSignal(prices, params) {
  const bb = calculateBollingerBands(prices, params.bb_period, params.bb_multiplier);
  const rsi = calculateRSI(prices, params.rsi_period);
  const price = prices[0]; // most recent

  // ENTRY: price below lower band AND RSI oversold — both must fire
  if (price < bb.lower && rsi < params.rsi_oversold) {
    return 'buy';  // Extreme dip + momentum confirmation
  }

  // EXIT: price recovered above middle band (reversion complete)
  if (price > bb.middle) {
    return 'sell'; // Mean reversion done — take profit
  }

  // EXIT: RSI overbought AND above upper band — extended move
  if (rsi > params.rsi_overbought && price > bb.upper) {
    return 'sell'; // Overbought — exit aggressively
  }

  return 'hold'; // Waiting for setup
}

// Relative Strength Index — measures momentum (0-100)
function calculateRSI(prices, period) {
  const changes = [];
  for (let i = 1; i < period + 1; i++) {
    changes.push(prices[i-1] - prices[i]);  // newest first
  }

  let avgGain = 0, avgLoss = 0;
  for (const c of changes) {
    if (c > 0) avgGain += c;
    else avgLoss += Math.abs(c);
  }
  avgGain /= period;
  avgLoss /= period;

  if (avgLoss === 0) return 100;
  const rs = avgGain / avgLoss;
  return 100 - (100 / (1 + rs));  // RSI formula
}

// Signal generator — runs on every tick
function rsiSignal(prices, params) {
  const rsi = calculateRSI(prices, params.rsi_period);  // 14

  if (rsi < params.oversold)   return 'buy';   // RSI < 30 → oversold
  if (rsi > params.overbought) return 'sell';  // RSI > 70 → overbought
  return 'hold';                            // 30-70 → neutral
}