Function forecastTrend

src/cli/maintain-stats.ts:117–130

(runs: MaintainRun[], nowMs: number, weeks = 8)

 * self-improvement loop is speeding up, cooling off, or holding steady, and where it's headed. PURE.
 */
export function forecastTrend(runs: MaintainRun[], nowMs: number, weeks = 8): MaintainForecast {
  const ys = trendByWeek(runs, nowMs, weeks);      // oldest→newest, length = weeks
  const n = ys.length;
  const weeklyAvg = n ? ys.reduce((a, b) => a + b, 0) / n : 0;
  // OLS over x = 0..n-1.
  const meanX = (n - 1) / 2;
  let num = 0, den = 0;
  for (let x = 0; x < n; x++) { num += (x - meanX) * (ys[x]! - weeklyAvg); den += (x - meanX) ** 2; }
  const slope = den ? num / den : 0;
  const intercept = weeklyAvg - slope * meanX;
  const nextWeek = Math.max(0, Math.round(intercept + slope * n));
  const direction = slope > 0.15 ? 'rising' : slope < -0.15 ? 'falling' : 'steady';
  return { weeklyAvg: Math.round(weeklyAvg * 100) / 100, slope: Math.round(slope * 100) / 100, direction, nextWeek, weeks: n };
}

/** Week-over-week self-improvement report from run timestamps. PURE (pass `nowMs`). */
export function weeklyReport(runs: MaintainRun[], nowMs: number): MaintainWeekly {