Jyotisha/frontend/src/lib/new-chat-timing.ts

/**
 * 「新建对话」 timing (BUG-1104). Browser Performance marks only: nothing is
 * sent anywhere and nothing personal is recorded. In DevTools → Performance
 * (or `performance.getEntriesByType("measure")`) a slow case shows as
 * `jyotisha:new-chat (warm|cold)` with its duration from click to a ready Home.
 */

const CLICK = "jyotisha:new-chat:click";
let pending = false;
let path: "warm" | "cold" | null = null;

function perf(): Performance | null {
  return typeof performance !== "undefined" && typeof performance.mark === "function" ? performance : null;
}

/** The sidebar's 「新建对话」 was clicked (either the link off `/` or the button on it). */
export function markNewChatClick(): void {
  const p = perf();
  if (!p) return;
  try {
    p.clearMarks(CLICK);
    p.mark(CLICK);
    pending = true;
    path = null;
  } catch {
    // Timing is best-effort.
  }
}

/** Which way the Home that mounts next decided to start. */
export function noteHomeStartPath(kind: "warm" | "cold"): void {
  if (pending) path ??= kind;
}

/** Home is revealed and usable; closes the measure opened by the click, once. */
export function markHomeReadyAfterNewChat(): void {
  const p = perf();
  if (!p || !pending) return;
  pending = false;
  try {
    p.measure(`jyotisha:new-chat (${path ?? "unknown"})`, CLICK);
  } catch {
    // The click mark was cleared by another tool; nothing to measure.
  }
}