#!/usr/bin/env node
// Reports and enforces compressed Control UI asset budgets after a production build.
import fs from "node:fs";
import path from "node:path";
import process from "node:process";
import { fileURLToPath } from "node:url";
import {
  CONTROL_UI_ROUTE_PRELOAD_ATTRIBUTE,
  selectControlUiRoutePreloads,
} from "../src/gateway/control-ui-route-preloads.ts";
import { reportLimitViolations } from "./lib/check-limits.mts";
import { CONTROL_UI_LOCALE_ENTRIES } from "./lib/control-ui-i18n-config.ts";

function isMetricsRecord(value: unknown): value is Record<string, unknown> {
  return value !== null && typeof value === "object" && !Array.isArray(value);
}

const KIB = 1024;
const STARTUP_JS_BASELINE_RATCHET_BYTES = 4096;
const BASELINE_UPDATE_COMMAND =
  'node --import ./scripts/tsx.mjs scripts/check-control-ui-performance.mts --update-baseline --reason "<reason>"';
const SCRIPT_DIR = path.dirname(fileURLToPath(import.meta.url));
const DEFAULT_STARTUP_BUDGET_BASELINE_PATH = path.resolve(
  SCRIPT_DIR,
  "../config/control-ui-startup-budget-baseline.json",
);

// Each landed change can consume this much ratchet tolerance, so small increases
// may accumulate. The fixed startup JS ceiling bounds that cumulative creep.
const CONTROL_UI_STARTUP_JS_GZIP_TOLERANCE_BYTES = 512;
const CONTROL_UI_STARTUP_JS_GZIP_BUILD_VARIANCE_BYTES = 64;
const CONTROL_UI_STARTUP_CSS_GZIP_TARGET_BYTES = 45 * KIB;
// Immediate Home and diagnostic frames approved in #147574, including shared header styles.
const CONTROL_UI_CSS_GZIP_GROWTH_BYTES = 1.5 * KIB;
// The opaque Mermaid sandbox loads one self-contained classic script only when
// a diagram is viewed. Keep its size visible without relaxing ordinary chunks.
const MERMAID_RENDERER_ASSET = /^assets\/mermaid\.min-[\w-]+\.js$/u;
const MERMAID_RENDERER_GZIP_BYTES = 960 * KIB;
// Locale catalogs are named Vite chunks loaded only after a language selection.
// Base and config-hint chunks share one budget because they activate atomically.
const CONTROL_UI_LOCALE_ASSET_PATTERNS = CONTROL_UI_LOCALE_ENTRIES.flatMap(({ locale }) => [
  {
    locale,
    kind: "base" as const,
    pattern: new RegExp(`^assets/${escapeRegExp(locale)}-[^/]+\\.js$`, "u"),
  },
  {
    locale,
    kind: "configHints" as const,
    pattern: new RegExp(`^assets/locale-config-hints-${escapeRegExp(locale)}-[^/]+\\.js$`, "u"),
  },
]);
const CONTROL_UI_LOCALE_GZIP_BYTES = 300 * KIB;

// Small, explicit headroom over the optimized baseline. Budget changes should
// accompany an intentional loading or chunking decision.
const controlUiPerformanceBudgets = {
  startupJsRequests: 18,
  startupCssRequests: 1,
  // Approved measured upload-control baseline; retain the fixed growth and variance allowances.
  startupJsGzipBytes: 371_771,
  // Keep 45 KiB advisory: tiny integrated changes must not exhaust the budget.
  // The fixed 50 KiB ceiling bounds accumulation of small changes.
  startupCssGzipBytes: 50 * KIB,
  largestJsGzipBytes: 215 * KIB,
  // Composer multiline surface (stack #124301) legitimately grew boot CSS;
  // operator decision 2026-08-25 rejected boot splitting due to precedence risk.
  // 53.0 KiB was exhausted by organic growth (main sat at 99.94% by 2026-08-29);
  // bumped to 53.5 KiB with operator approval on PR #132054. 2026-09-02: side
  // panel, workboard chip, and Lobsterdex styles moved to their lazy owners,
  // measured boot sheet 52,337 B; ceiling lowered to keep ~1 KiB headroom.
  largestCssGzipBytes: 53_400,
} satisfies Record<string, number>;
export const CONTROL_UI_PERFORMANCE_BUDGETS = Object.freeze(controlUiPerformanceBudgets);

function controlUiAssetPathFromUrl(value: string): string | null {
  const normalized = value.split(/[?#]/u, 1)[0]?.replace(/\\/gu, "/") ?? "";
  const markerIndex = normalized.lastIndexOf("assets/");
  if (markerIndex === -1) {
    return null;
  }
  const assetPath = normalized.slice(markerIndex);
  if (assetPath.includes("../") || !/\.(?:css|js)$/u.test(assetPath)) {
    return null;
  }
  return assetPath;
}

export function extractControlUiStartupAssetPaths(html: string): string[] {
  const assets = new Set<string>();
  for (const tag of html.matchAll(/<(?:link|script)\b[^>]*>/giu)) {
    const attribute = tag[0].match(/\s(?:href|src)\s*=\s*["']([^"']+)["']/iu);
    const assetPath = attribute?.[1] ? controlUiAssetPathFromUrl(attribute[1]) : null;
    if (assetPath) {
      assets.add(assetPath);
    }
  }
  return [...assets].toSorted((left, right) => left.localeCompare(right));
}

function readAssetMetrics(assetsDir: string, entry: fs.Dirent) {
  const file = `assets/${entry.name}`;
  const sourcePath = path.join(assetsDir, entry.name);
  const gzipPath = `${sourcePath}.gz`;
  const brotliPath = `${sourcePath}.br`;
  for (const sidecarPath of [gzipPath, brotliPath]) {
    if (!fs.existsSync(sidecarPath)) {
      throw new Error(`Control UI performance check missing ${path.basename(sidecarPath)}`);
    }
  }
  const type = entry.name.endsWith(".js") ? "js" : "css";
  return {
    file,
    type,
    rawBytes: fs.statSync(sourcePath).size,
    gzipBytes: fs.statSync(gzipPath).size,
    brotliBytes: fs.statSync(brotliPath).size,
  };
}

function summarizeAssets(assets: Array<ReturnType<typeof readAssetMetrics>>) {
  return assets.reduce(
    (summary, asset) => ({
      requests: summary.requests + 1,
      rawBytes: summary.rawBytes + asset.rawBytes,
      gzipBytes: summary.gzipBytes + asset.gzipBytes,
      brotliBytes: summary.brotliBytes + asset.brotliBytes,
    }),
    { requests: 0, rawBytes: 0, gzipBytes: 0, brotliBytes: 0 },
  );
}

function largestAsset(assets: Array<ReturnType<typeof readAssetMetrics>>) {
  return assets.toSorted(
    (left, right) => right.gzipBytes - left.gzipBytes || left.file.localeCompare(right.file),
  )[0]!;
}

function escapeRegExp(value: string): string {
  return value.replace(/[.*+?^${}()|[\]\\]/gu, "\\$&");
}

function controlUiLocaleAssetIdentity(
  file: string,
): { locale: string; kind: "base" | "configHints" } | null {
  const match = CONTROL_UI_LOCALE_ASSET_PATTERNS.find(({ pattern }) => pattern.test(file));
  return match ? { locale: match.locale, kind: match.kind } : null;
}

function collectControlUiLocaleAssetGroups(assets: Array<ReturnType<typeof readAssetMetrics>>) {
  const groups = new Map<
    string,
    {
      locale: string;
      base: Array<ReturnType<typeof readAssetMetrics>>;
      configHints: Array<ReturnType<typeof readAssetMetrics>>;
    }
  >();
  for (const asset of assets) {
    const identity = controlUiLocaleAssetIdentity(asset.file);
    if (!identity) {
      continue;
    }
    const group = groups.get(identity.locale) ?? {
      locale: identity.locale,
      base: [],
      configHints: [],
    };
    group[identity.kind].push(asset);
    groups.set(identity.locale, group);
  }
  return [...groups.values()];
}

export function collectControlUiPerformanceMetrics(distDir: string) {
  const assetsDir = path.join(distDir, "assets");
  const html = fs.readFileSync(path.join(distDir, "index.html"), "utf8");
  const assets = fs
    .readdirSync(assetsDir, { withFileTypes: true })
    .filter((entry) => entry.isFile() && /\.(?:css|js)$/u.test(entry.name))
    .map((entry) => readAssetMetrics(assetsDir, entry));
  const assetsByFile = new Map(assets.map((asset) => [asset.file, asset]));
  const collectBootAssets = (document: string) => {
    const bootAssets = extractControlUiStartupAssetPaths(document).map((file) => {
      const asset = assetsByFile.get(file);
      if (!asset) {
        throw new Error(`Control UI performance check cannot find startup asset ${file}`);
      }
      return asset;
    });
    return {
      js: summarizeAssets(bootAssets.filter((asset) => asset.type === "js")),
      css: summarizeAssets(bootAssets.filter((asset) => asset.type === "css")),
      assets: bootAssets,
    };
  };
  // Preserve the historical entry budget; route preloads also account for the
  // measured immediate dynamic imports that it never included.
  const startup = collectBootAssets(selectControlUiRoutePreloads(html, null));
  const routeBoot = html.includes(CONTROL_UI_ROUTE_PRELOAD_ATTRIBUTE)
    ? {
        chat: collectBootAssets(selectControlUiRoutePreloads(html, "chat")),
        new: collectBootAssets(selectControlUiRoutePreloads(html, "new")),
      }
    : null;
  const jsAssets = assets.filter((asset) => asset.type === "js");
  const mermaidRenderer = jsAssets.filter((asset) => MERMAID_RENDERER_ASSET.test(asset.file));
  const localeCatalogs = jsAssets.filter(
    (asset) => controlUiLocaleAssetIdentity(asset.file) !== null,
  );
  const ordinaryJsAssets = jsAssets.filter(
    (asset) =>
      !MERMAID_RENDERER_ASSET.test(asset.file) && controlUiLocaleAssetIdentity(asset.file) === null,
  );
  const cssAssets = assets.filter((asset) => asset.type === "css");
  if (ordinaryJsAssets.length === 0 || cssAssets.length === 0 || startup.assets.length === 0) {
    throw new Error("Control UI performance check found an incomplete production bundle");
  }
  return {
    schemaVersion: 1 as const,
    startup,
    routeBoot,
    total: {
      js: summarizeAssets(jsAssets),
      css: summarizeAssets(cssAssets),
    },
    largest: {
      js: largestAsset(ordinaryJsAssets),
      css: largestAsset(cssAssets),
    },
    mermaidRenderer,
    localeCatalogs,
  };
}

export function evaluateControlUiPerformanceBudgets(
  metrics: ReturnType<typeof collectControlUiPerformanceMetrics>,
  budgets: Readonly<typeof CONTROL_UI_PERFORMANCE_BUDGETS> = CONTROL_UI_PERFORMANCE_BUDGETS,
  startupBudgetBaseline: Readonly<ControlUiStartupBudgetBaseline> | null = null,
  startupJsTolerance = CONTROL_UI_STARTUP_JS_GZIP_TOLERANCE_BYTES,
  baseMetrics: ReturnType<typeof collectControlUiPerformanceMetrics> | null = null,
) {
  const baselineBytes = startupBudgetBaseline?.startupJsGzipBytes;
  const startupJsLimits = resolveControlUiStartupJsGzipLimits(
    budgets,
    startupBudgetBaseline,
    startupJsTolerance,
  );
  const localeGroups = collectControlUiLocaleAssetGroups(metrics.localeCatalogs);
  const startupAssetFiles = new Set(
    [
      ...metrics.startup.assets,
      ...Object.values(metrics.routeBoot ?? {}).flatMap((route) => route.assets),
    ].map((asset) => asset.file),
  );
  const checks: Array<[string, number, number, "count" | "bytes"]> = [
    ["startup JS requests", metrics.startup.js.requests, budgets.startupJsRequests, "count"],
    ["startup CSS requests", metrics.startup.css.requests, budgets.startupCssRequests, "count"],
    ["startup JS gzip", metrics.startup.js.gzipBytes, startupJsLimits.enforcementLimit, "bytes"],
    ["startup CSS gzip", metrics.startup.css.gzipBytes, budgets.startupCssGzipBytes, "bytes"],
    ["largest JS gzip", metrics.largest.js.gzipBytes, budgets.largestJsGzipBytes, "bytes"],
    ["largest CSS gzip", metrics.largest.css.gzipBytes, budgets.largestCssGzipBytes, "bytes"],
    ["isolated Mermaid JS assets", metrics.mermaidRenderer.length, 1, "count"],
    [
      "isolated Mermaid JS gzip",
      summarizeAssets(metrics.mermaidRenderer).gzipBytes,
      MERMAID_RENDERER_GZIP_BYTES,
      "bytes",
    ],
    [
      "startup Mermaid JS assets",
      [...startupAssetFiles].filter((file) => MERMAID_RENDERER_ASSET.test(file)).length,
      0,
      "count",
    ],
    [
      "locale catalog JS assets",
      metrics.localeCatalogs.length,
      CONTROL_UI_LOCALE_ENTRIES.length * 2,
      "count",
    ],
    [
      "locale catalog base JS assets per locale",
      Math.max(0, ...localeGroups.map((group) => group.base.length)),
      1,
      "count",
    ],
    [
      "locale config-hint JS assets per locale",
      Math.max(0, ...localeGroups.map((group) => group.configHints.length)),
      1,
      "count",
    ],
    [
      "largest locale catalog pair JS gzip",
      Math.max(
        0,
        ...localeGroups.map(
          (group) => summarizeAssets([...group.base, ...group.configHints]).gzipBytes,
        ),
      ),
      CONTROL_UI_LOCALE_GZIP_BYTES,
      "bytes",
    ],
    [
      "startup locale catalog JS assets",
      [...startupAssetFiles].filter((file) => controlUiLocaleAssetIdentity(file) !== null).length,
      0,
      "count",
    ],
  ];
  const violations = checks.flatMap(([metric, actual, limit, unit]) =>
    actual > limit ? [{ metric, actual, limit, unit }] : [],
  );
  if (baseMetrics) {
    for (const area of ["startup", "largest"] as const) {
      const growth = metrics[area].css.gzipBytes - baseMetrics[area].css.gzipBytes;
      if (growth >= CONTROL_UI_CSS_GZIP_GROWTH_BYTES) {
        violations.push({
          metric: `${area} CSS gzip growth`,
          actual: growth,
          limit: CONTROL_UI_CSS_GZIP_GROWTH_BYTES - 1,
          unit: "bytes",
        });
      }
    }
  }
  if (baselineBytes !== undefined && baselineBytes > budgets.startupJsGzipBytes) {
    violations.unshift({
      metric: "startup JS gzip baseline",
      actual: baselineBytes,
      limit: budgets.startupJsGzipBytes,
      unit: "bytes",
    });
  }
  return violations;
}

function resolveControlUiStartupJsGzipLimits(
  budgets: Readonly<typeof CONTROL_UI_PERFORMANCE_BUDGETS>,
  startupBudgetBaseline: Readonly<ControlUiStartupBudgetBaseline> | null,
  startupJsTolerance: number,
) {
  const baselineCap = budgets.startupJsGzipBytes;
  if (!startupBudgetBaseline) {
    return {
      baselineCap,
      growthLimit: baselineCap,
      buildVariance: 0,
      enforcementLimit: baselineCap,
    };
  }
  const growthLimit =
    Math.min(startupBudgetBaseline.startupJsGzipBytes, baselineCap) + startupJsTolerance;
  return {
    baselineCap,
    growthLimit,
    buildVariance: CONTROL_UI_STARTUP_JS_GZIP_BUILD_VARIANCE_BYTES,
    enforcementLimit: growthLimit + CONTROL_UI_STARTUP_JS_GZIP_BUILD_VARIANCE_BYTES,
  };
}

type ControlUiPerformanceBudgetViolation = ReturnType<
  typeof evaluateControlUiPerformanceBudgets
>[number];

function formatControlUiPerformanceBytes(bytes: number): string {
  return bytes < KIB ? `${bytes} B` : `${(bytes / KIB).toFixed(1)} KiB`;
}

function formatRequestCount(count: number): string {
  return `${count} ${count === 1 ? "request" : "requests"}`;
}

function formatAssetSummary(summary: ReturnType<typeof summarizeAssets>): string {
  return `${formatRequestCount(summary.requests)}, ${formatControlUiPerformanceBytes(summary.gzipBytes)} gzip (${summary.gzipBytes} B), ${formatControlUiPerformanceBytes(summary.brotliBytes)} br, ${summary.rawBytes} B raw`;
}

function controlUiPerformanceWarnings(
  metrics: ReturnType<typeof collectControlUiPerformanceMetrics>,
  budgets: Readonly<typeof CONTROL_UI_PERFORMANCE_BUDGETS>,
): string[] {
  const warnings: string[] = [];
  if (metrics.startup.css.gzipBytes > CONTROL_UI_STARTUP_CSS_GZIP_TARGET_BYTES) {
    warnings.push(
      `startup CSS gzip is above the ${CONTROL_UI_STARTUP_CSS_GZIP_TARGET_BYTES} B advisory target; remaining hard-ceiling headroom: ${budgets.startupCssGzipBytes - metrics.startup.css.gzipBytes} B`,
    );
  }
  const largestCssHeadroom = budgets.largestCssGzipBytes - metrics.largest.css.gzipBytes;
  if (largestCssHeadroom < CONTROL_UI_CSS_GZIP_GROWTH_BYTES) {
    warnings.push(`largest CSS gzip has ${largestCssHeadroom} B of hard-ceiling headroom`);
  }
  return warnings;
}

function formatViolation(violation: ControlUiPerformanceBudgetViolation): string {
  const format = violation.unit === "bytes" ? formatControlUiPerformanceBytes : String;
  const actual = format(violation.actual);
  const limit = format(violation.limit);
  const exactBytes =
    violation.unit === "bytes" && actual === limit
      ? ` (${violation.actual} B vs ${violation.limit} B)`
      : "";
  return `${violation.metric}: ${actual} exceeds ${limit}${exactBytes}`;
}

export function formatControlUiPerformanceReport(
  metrics: ReturnType<typeof collectControlUiPerformanceMetrics>,
  budgets: Readonly<typeof CONTROL_UI_PERFORMANCE_BUDGETS> = CONTROL_UI_PERFORMANCE_BUDGETS,
  startupBudgetBaseline: Readonly<ControlUiStartupBudgetBaseline> | null = null,
  startupJsTolerance: number = CONTROL_UI_STARTUP_JS_GZIP_TOLERANCE_BYTES,
  baseMetrics: ReturnType<typeof collectControlUiPerformanceMetrics> | null = null,
): string {
  const startupJsLimits = resolveControlUiStartupJsGzipLimits(
    budgets,
    startupBudgetBaseline,
    startupJsTolerance,
  );
  const violations = evaluateControlUiPerformanceBudgets(
    metrics,
    budgets,
    startupBudgetBaseline,
    startupJsTolerance,
    baseMetrics,
  );
  const lines = [
    "Control UI performance:",
    `  measurement: shipped gzip sidecars; Node ${process.version}`,
    `  startup JS: ${formatAssetSummary(metrics.startup.js)} (limits: ${formatRequestCount(budgets.startupJsRequests)}, ${formatControlUiPerformanceBytes(startupJsLimits.enforcementLimit)} gzip / ${startupJsLimits.enforcementLimit} B)`,
  ];
  if (startupBudgetBaseline) {
    lines.push(
      `  startup JS gzip vs baseline: ${metrics.startup.js.gzipBytes} B (baseline ${startupBudgetBaseline.startupJsGzipBytes} B + growth allowance ${startupJsTolerance} B = growth limit ${startupJsLimits.growthLimit} B; build-variance allowance ${startupJsLimits.buildVariance} B; enforcement limit ${startupJsLimits.enforcementLimit} B; max committed baseline ${startupJsLimits.baselineCap} B)`,
    );
  }
  lines.push(
    `  startup CSS: ${formatAssetSummary(metrics.startup.css)} (limits: ${formatRequestCount(budgets.startupCssRequests)}, advisory target ${CONTROL_UI_STARTUP_CSS_GZIP_TARGET_BYTES} B, hard ceiling ${budgets.startupCssGzipBytes} B; headroom ${budgets.startupCssGzipBytes - metrics.startup.css.gzipBytes} B)`,
    `  largest ordinary JS: ${metrics.largest.js.file}, ${formatControlUiPerformanceBytes(metrics.largest.js.gzipBytes)} gzip (limit: ${formatControlUiPerformanceBytes(budgets.largestJsGzipBytes)})`,
    `  largest CSS: ${metrics.largest.css.file}, ${metrics.largest.css.gzipBytes} B gzip (hard ceiling ${budgets.largestCssGzipBytes} B; headroom ${budgets.largestCssGzipBytes - metrics.largest.css.gzipBytes} B)`,
    `  all JS: ${formatAssetSummary(metrics.total.js)}`,
    `  all CSS: ${formatAssetSummary(metrics.total.css)}`,
  );
  if (metrics.routeBoot) {
    lines.push(
      "  route boot accounting: initial-entry assets plus measured immediate dynamic imports; existing initial-entry limits unchanged",
    );
    for (const route of ["chat", "new"] as const) {
      const boot = metrics.routeBoot[route];
      lines.push(
        `  ${route} boot JS: ${formatAssetSummary(boot.js)} (${boot.js.gzipBytes - metrics.startup.js.gzipBytes} B beyond initial-entry JS)`,
        `  ${route} boot CSS: ${formatAssetSummary(boot.css)}`,
      );
      if (baseMetrics) {
        const baseBoot = baseMetrics.routeBoot?.[route];
        if (baseBoot) {
          for (const type of ["js", "css"] as const) {
            const growth = boot[type].gzipBytes - baseBoot[type].gzipBytes;
            lines.push(
              `  ${route} boot ${type.toUpperCase()} gzip vs base: ${baseBoot[type].gzipBytes} B -> ${boot[type].gzipBytes} B (${growth >= 0 ? "+" : ""}${growth} B); requests ${baseBoot[type].requests} -> ${boot[type].requests}`,
            );
          }
        } else {
          lines.push(`  ${route} boot vs base: unavailable (base has no route preload templates)`);
        }
      }
    }
  } else {
    lines.push("  route boot accounting: unavailable (build has no route preload templates)");
  }
  if (baseMetrics) {
    for (const area of ["startup", "largest"] as const) {
      const growth = metrics[area].css.gzipBytes - baseMetrics[area].css.gzipBytes;
      lines.push(
        `  ${area} CSS gzip vs base: ${baseMetrics[area].css.gzipBytes} B -> ${metrics[area].css.gzipBytes} B (${growth >= 0 ? "+" : ""}${growth} B; growth below ${CONTROL_UI_CSS_GZIP_GROWTH_BYTES} B allowed)`,
      );
    }
  }
  for (const warning of controlUiPerformanceWarnings(metrics, budgets)) {
    lines.push(`  warning: ${warning}`);
  }
  if (metrics.mermaidRenderer.length > 0) {
    lines.push(
      `  isolated Mermaid JS: ${formatAssetSummary(summarizeAssets(metrics.mermaidRenderer))} (limits: 1 deferred asset, ${formatControlUiPerformanceBytes(MERMAID_RENDERER_GZIP_BYTES)} gzip; forbidden at startup)`,
    );
  }
  if (metrics.localeCatalogs.length > 0) {
    const localeGroups = collectControlUiLocaleAssetGroups(metrics.localeCatalogs);
    const largestLocalePair = localeGroups.toSorted(
      (left, right) =>
        summarizeAssets([...right.base, ...right.configHints]).gzipBytes -
          summarizeAssets([...left.base, ...left.configHints]).gzipBytes ||
        left.locale.localeCompare(right.locale),
    )[0]!;
    const largestLocalePairSummary = summarizeAssets([
      ...largestLocalePair.base,
      ...largestLocalePair.configHints,
    ]);
    lines.push(
      `  locale catalog JS: ${formatAssetSummary(summarizeAssets(metrics.localeCatalogs))} (largest pair: ${largestLocalePair.locale}, ${formatControlUiPerformanceBytes(largestLocalePairSummary.gzipBytes)} gzip; limits: 1 base + 1 config-hint asset per locale, ${formatControlUiPerformanceBytes(CONTROL_UI_LOCALE_GZIP_BYTES)} combined; forbidden at startup)`,
    );
  }
  if (
    startupBudgetBaseline &&
    metrics.startup.js.gzipBytes + STARTUP_JS_BASELINE_RATCHET_BYTES <
      startupBudgetBaseline.startupJsGzipBytes
  ) {
    lines.push(
      `  hint: startup JS gzip is more than ${STARTUP_JS_BASELINE_RATCHET_BYTES} B below the ${startupBudgetBaseline.startupJsGzipBytes} B baseline; lower it with ${BASELINE_UPDATE_COMMAND}`,
    );
  }
  if (violations.length > 0) {
    lines.push(
      "  violations:",
      ...violations.map((violation) => `    - ${formatViolation(violation)}`),
    );
  }
  return lines.join("\n");
}

function isIsoDate(value: string): boolean {
  if (!/^\d{4}-\d{2}-\d{2}$/u.test(value)) {
    return false;
  }
  const date = new Date(`${value}T00:00:00Z`);
  return !Number.isNaN(date.valueOf()) && date.toISOString().slice(0, 10) === value;
}

function readControlUiStartupBudgetBaseline(baselinePath: string): ControlUiStartupBudgetBaseline {
  try {
    const parsed: unknown = JSON.parse(fs.readFileSync(baselinePath, "utf8"));
    const record: Record<string, unknown> = isMetricsRecord(parsed) ? parsed : {};
    const { startupJsGzipBytes, reason, updatedAt } = record;
    if (
      typeof startupJsGzipBytes !== "number" ||
      !Number.isSafeInteger(startupJsGzipBytes) ||
      startupJsGzipBytes < 0 ||
      typeof reason !== "string" ||
      reason.trim().length === 0 ||
      typeof updatedAt !== "string" ||
      !isIsoDate(updatedAt)
    ) {
      throw new Error(
        "expected non-negative integer startupJsGzipBytes, non-empty reason, and YYYY-MM-DD updatedAt",
      );
    }
    return { startupJsGzipBytes, reason, updatedAt };
  } catch (error) {
    const detail = error instanceof Error ? error.message : String(error);
    throw new Error(
      `Cannot read Control UI startup budget baseline ${baselinePath}: ${detail}. Regenerate it with ${BASELINE_UPDATE_COMMAND}.`,
      { cause: error },
    );
  }
}

function writeControlUiStartupBudgetBaseline(
  baselinePath: string,
  startupJsGzipBytes: number,
  reason: string,
) {
  if (startupJsGzipBytes > CONTROL_UI_PERFORMANCE_BUDGETS.startupJsGzipBytes) {
    throw new Error("startup JS gzip baseline exceeds the committed-baseline cap");
  }
  const baseline = {
    startupJsGzipBytes,
    reason,
    updatedAt: new Date().toISOString().slice(0, 10),
  };
  fs.writeFileSync(baselinePath, `${JSON.stringify(baseline, null, 2)}\n`);
  return baseline;
}

type ControlUiStartupBudgetBaseline = ReturnType<typeof writeControlUiStartupBudgetBaseline>;

function validateExplicitStartupJsBytes(
  startupJsBytes: number,
  currentBaseline: ControlUiStartupBudgetBaseline,
): void {
  const delta = Math.abs(startupJsBytes - currentBaseline.startupJsGzipBytes);
  if (delta > STARTUP_JS_BASELINE_RATCHET_BYTES) {
    throw new Error(
      `startup JS gzip baseline update: ${startupJsBytes} B differs from current baseline ${currentBaseline.startupJsGzipBytes} B by ${delta} B, exceeding the ${STARTUP_JS_BASELINE_RATCHET_BYTES} B ratchet`,
    );
  }
}

export function runControlUiPerformanceCheck(
  distDir: string,
  budgets: Readonly<typeof CONTROL_UI_PERFORMANCE_BUDGETS> = CONTROL_UI_PERFORMANCE_BUDGETS,
  baselinePath = DEFAULT_STARTUP_BUDGET_BASELINE_PATH,
  baseDistDir?: string,
) {
  const startupBudgetBaseline = readControlUiStartupBudgetBaseline(baselinePath);
  const metrics = collectControlUiPerformanceMetrics(distDir);
  const baseMetrics = baseDistDir ? collectControlUiPerformanceMetrics(baseDistDir) : null;
  const violations = evaluateControlUiPerformanceBudgets(
    metrics,
    budgets,
    startupBudgetBaseline,
    undefined,
    baseMetrics,
  );
  const report = formatControlUiPerformanceReport(
    metrics,
    budgets,
    startupBudgetBaseline,
    undefined,
    baseMetrics,
  );
  return {
    metrics,
    baseMetrics,
    budgets,
    startupBudgetBaseline,
    startupJsTolerance: CONTROL_UI_STARTUP_JS_GZIP_TOLERANCE_BYTES,
    startupJsBuildVariance: CONTROL_UI_STARTUP_JS_GZIP_BUILD_VARIANCE_BYTES,
    violations,
    warnings: controlUiPerformanceWarnings(metrics, budgets),
    report,
  };
}

function main(argv: string[] = process.argv.slice(2)): void {
  let json = false;
  let reportOnly = false;
  let distDir: string | undefined;
  let baseDistDir: string | undefined;
  let updateBaseline = false;
  let reason: string | undefined;
  let startupJsBytes: number | undefined;
  for (let index = 0; index < argv.length; index += 1) {
    const arg = argv[index];
    if (arg === "--json") {
      json = true;
    } else if (arg === "--report-only") {
      reportOnly = true;
    } else if (arg === "--base-dist" || arg === "--dist") {
      const value = argv[++index];
      if (!value || value.startsWith("--")) {
        throw new Error(`${arg} requires a directory`);
      }
      if (arg === "--dist") {
        distDir = path.resolve(value);
      } else {
        baseDistDir = path.resolve(value);
      }
    } else if (arg === "--update-baseline") {
      updateBaseline = true;
    } else if (arg === "--reason") {
      reason = argv[index + 1];
      if (!reason || reason.trim().length === 0 || reason.startsWith("--")) {
        throw new Error("--reason requires a non-empty value");
      }
      index += 1;
    } else if (arg === "--startup-js-bytes") {
      const value = argv[index + 1];
      if (!value || !/^[1-9]\d*$/u.test(value)) {
        throw new Error("--startup-js-bytes requires a positive integer");
      }
      startupJsBytes = Number(value);
      if (!Number.isSafeInteger(startupJsBytes)) {
        throw new Error("--startup-js-bytes requires a positive integer");
      }
      index += 1;
    } else {
      throw new Error(`Unknown option: ${arg}`);
    }
  }
  if (reason !== undefined && !updateBaseline) {
    throw new Error("--reason requires --update-baseline");
  }
  if (startupJsBytes !== undefined && !updateBaseline) {
    throw new Error("--startup-js-bytes requires --update-baseline");
  }
  if (json && updateBaseline) {
    throw new Error("--json cannot be combined with --update-baseline");
  }
  if (updateBaseline && (reportOnly || baseDistDir || distDir)) {
    throw new Error(
      "--report-only, --base-dist and --dist cannot be combined with --update-baseline",
    );
  }
  distDir ??= path.resolve(SCRIPT_DIR, "../dist/control-ui");
  if (updateBaseline) {
    if (startupJsBytes !== undefined) {
      const currentBaseline = readControlUiStartupBudgetBaseline(
        DEFAULT_STARTUP_BUDGET_BASELINE_PATH,
      );
      validateExplicitStartupJsBytes(startupJsBytes, currentBaseline);
    }
    const nextStartupJsBytes =
      startupJsBytes ?? collectControlUiPerformanceMetrics(distDir).startup.js.gzipBytes;
    const baseline = writeControlUiStartupBudgetBaseline(
      DEFAULT_STARTUP_BUDGET_BASELINE_PATH,
      nextStartupJsBytes,
      reason ?? "manual baseline update",
    );
    process.stdout.write(
      `Updated config/control-ui-startup-budget-baseline.json to ${baseline.startupJsGzipBytes} B (${baseline.reason}).\n`,
    );
    return;
  }
  const result = runControlUiPerformanceCheck(distDir, undefined, undefined, baseDistDir);
  if (json) {
    process.stdout.write(`${JSON.stringify(result, null, 2)}\n`);
  } else {
    process.stdout.write(`${result.report}\n`);
  }
  if (!reportOnly) {
    const artifactContractMetrics = new Set([
      "isolated Mermaid JS assets",
      "startup Mermaid JS assets",
      "locale catalog base JS assets per locale",
      "locale config-hint JS assets per locale",
      "startup locale catalog JS assets",
    ]);
    const limitsFailed = reportLimitViolations(
      result.violations
        .filter((violation) => !artifactContractMetrics.has(violation.metric))
        .map((violation) => ({
          file:
            violation.metric === "startup JS gzip baseline"
              ? "config/control-ui-startup-budget-baseline.json"
              : "scripts/check-control-ui-performance.mts",
          title: "Control UI asset budget",
          message: formatViolation(violation),
        })),
    );
    if (
      limitsFailed ||
      result.violations.some((violation) => artifactContractMetrics.has(violation.metric))
    ) {
      process.exitCode = 1;
    }
  }
}

if (process.argv[1] && path.resolve(process.argv[1]) === fileURLToPath(import.meta.url)) {
  try {
    main();
  } catch (error) {
    console.error(error instanceof Error ? error.message : String(error));
    process.exitCode = 1;
  }
}