perf: cut cold route compilation and unblock preview images (#6441)

scripts/benchmarks/dev-benchmark-lib.mts

@@ -0,0 +1,81 @@
+export type NumericSummary = {
+  count: number;
+  min: number | null;
+  median: number | null;
+  p95: number | null;
+  max: number | null;
+  standardDeviation: number | null;
+  outliers: number[];
+};
+
+export const normalizeTrpcPath = (requestUrl: string) => {
+  try {
+    const url = new URL(requestUrl, "http://benchmark.invalid");
+    url.searchParams.sort();
+    return url.pathname + url.search;
+  } catch {
+    return requestUrl;
+  }
+};
+
+export const countDuplicateTrpcPaths = (requestUrls: string[]) => {
+  const paths = requestUrls.map(normalizeTrpcPath);
+  return Math.max(0, paths.length - new Set(paths).size);
+};
+
+const values = (numbers: Array<number | null | undefined>) =>
+  numbers.filter((value): value is number => typeof value === "number" && value >= 0).toSorted((a, b) => a - b);
+
+export const summarize = (numbers: Array<number | null | undefined>): NumericSummary => {
+  const sorted = values(numbers);
+  if (sorted.length === 0) {
+    return { count: 0, min: null, median: null, p95: null, max: null, standardDeviation: null, outliers: [] };
+  }
+
+  const middleIndex = Math.floor(sorted.length / 2);
+  let median = sorted[middleIndex] ?? 0;
+  if (sorted.length % 2 === 0) {
+    median = ((sorted[middleIndex - 1] ?? 0) + median) / 2;
+  }
+  const p95Index = Math.min(sorted.length - 1, Math.ceil(sorted.length * 0.95) - 1);
+  const mean = sorted.reduce((total, value) => total + value, 0) / sorted.length;
+  const variance = sorted.reduce((total, value) => total + (value - mean) ** 2, 0) / sorted.length;
+  const firstQuartile = sorted[Math.floor((sorted.length - 1) * 0.25)] ?? 0;
+  const thirdQuartile = sorted[Math.floor((sorted.length - 1) * 0.75)] ?? 0;
+  const iqr = thirdQuartile - firstQuartile;
+  const outlierLimit = thirdQuartile + Math.max(1, iqr * 1.5);
+
+  return {
+    count: sorted.length,
+    min: sorted[0] ?? null,
+    median,
+    p95: sorted.length >= 20 ? (sorted[p95Index] ?? null) : null,
+    max: sorted.at(-1) ?? null,
+    standardDeviation: Math.round(Math.sqrt(variance)),
+    outliers: sorted.filter((value) => value > outlierLimit),
+  };
+};
+
+export const validateBrowserMeasurement = (measurement: {
+  responseStatus: number | null;
+  domContentLoadedMs: number;
+  boardHydratedMs: number | null;
+  widgetsReadyMs?: number | null;
+  widgetCount?: number;
+  coldImmediateInteractionMs?: number | null;
+  postIdleWarmInteractionMs?: number | null;
+  error?: string;
+}) => {
+  const errors: string[] = [];
+  if (measurement.error) errors.push(measurement.error);
+  if (measurement.responseStatus === null) errors.push("browser navigation returned no response");
+  else if (measurement.responseStatus < 200 || measurement.responseStatus >= 300)
+    errors.push(`browser navigation returned HTTP ${measurement.responseStatus}`);
+  if (measurement.domContentLoadedMs < 0) errors.push("DOMContentLoaded timing is missing");
+  if (measurement.boardHydratedMs === null) errors.push("board hydration marker is missing");
+  if (measurement.widgetsReadyMs === null) errors.push("widget readiness marker is missing");
+  if (measurement.widgetCount === 0) errors.push("representative board contains no widgets");
+  if (measurement.coldImmediateInteractionMs === null) errors.push("cold immediate interaction timing is missing");
+  if (measurement.postIdleWarmInteractionMs === null) errors.push("post-idle warm interaction timing is missing");
+  return errors;
+};