fix(client): авто-перезагрузка чанков в окне 5 минут вместо one-shot флага

При ChunkLoadError граница перезагружала страницу один раз, гейтируя
булевым флагом в sessionStorage, который никогда не сбрасывался. Из-за
этого ВТОРОЙ деплой за время жизни вкладки не давал авто-восстановления:
пользователь застревал на битом чанке без перезагрузки.

Заменяю one-shot флаг на счётчик по временному окну: не более одной
авто-перезагрузки за 5 минут. В sessionStorage храню метку времени
последней перезагрузки; на ChunkLoadError перезагружаемся только если
прошлая была раньше окна (или её не было), иначе проваливаемся в ручной
UI без перезагрузки. Это восстанавливает работу через несколько деплоев,
но не даёт бесконечного цикла при навсегда битом lazy-чанке (сброс флага
после успешного маунта отвергнут: оболочка монтируется, чанк 404 —
и цикл).

Решение об окне вынесено в чистый хелпер shouldAutoReload(now,
lastReloadAt, windowMs) и покрыто юнит-тестами: никогда-не-грузили →
можно; 6 минут назад → можно; 1 минуту назад → нельзя.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/client/src/components/chunk-load-error-boundary.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from "vitest";
-import { isChunkLoadError } from "./chunk-load-error-boundary";
+import { isChunkLoadError, shouldAutoReload } from "./chunk-load-error-boundary";
 
 // The detector decides whether a caught render error is a stale-deploy chunk-404
 // (→ auto-reload to fetch the new manifest) vs a genuine app error (→ generic
@@ -35,3 +35,31 @@ describe("isChunkLoadError", () => {
     expect(isChunkLoadError(err)).toBe(false);
   });
 });
+
+// The window gate replaces the old one-shot flag: it must permit recovery across
+// several deploys in one tab (each > window apart) while still stopping an infinite
+// reload loop when a lazy chunk is permanently broken (a second failure < window).
+describe("shouldAutoReload", () => {
+  const WINDOW = 5 * 60 * 1000;
+  const NOW = 1_000_000_000_000;
+
+  it("allows a reload when we have never auto-reloaded", () => {
+    expect(shouldAutoReload(NOW, null, WINDOW)).toBe(true);
+  });
+
+  it("allows a reload when the last one was 6 minutes ago (outside the window)", () => {
+    expect(shouldAutoReload(NOW, NOW - 6 * 60 * 1000, WINDOW)).toBe(true);
+  });
+
+  it("blocks a reload when the last one was 1 minute ago (inside the window)", () => {
+    expect(shouldAutoReload(NOW, NOW - 1 * 60 * 1000, WINDOW)).toBe(false);
+  });
+
+  it("blocks a reload exactly at the window boundary (not strictly older)", () => {
+    expect(shouldAutoReload(NOW, NOW - WINDOW, WINDOW)).toBe(false);
+  });
+
+  it("allows a reload when the stored timestamp is unparseable (NaN)", () => {
+    expect(shouldAutoReload(NOW, NaN, WINDOW)).toBe(true);
+  });
+});

apps/client/src/components/chunk-load-error-boundary.tsx

@@ -2,7 +2,25 @@ import { ReactNode } from "react";
 import { ErrorBoundary } from "react-error-boundary";
 import { Button, Center, Stack, Text } from "@mantine/core";
 
-const RELOAD_FLAG = "chunk-reload-attempted";
+// sessionStorage key holding the epoch-ms timestamp of the last automatic reload.
+const RELOAD_AT_KEY = "chunk-reload-at";
+// Allow at most one automatic reload per this window. A stale-deploy 404 is cured
+// by a single reload, so anything inside the window is treated as a reload loop
+// (permanently-broken chunk) and falls through to the manual UI. A window (rather
+// than a one-shot flag) lets a SECOND deploy in the same tab's lifetime recover too.
+const RELOAD_WINDOW_MS = 5 * 60 * 1000;
+
+// Pure window decision, unit-tested in isolation: auto-reload only if we have never
+// auto-reloaded (lastReloadAt null/NaN) or the last one was strictly older than the
+// window. Anything inside the window is suppressed to break an infinite reload loop.
+export function shouldAutoReload(
+  now: number,
+  lastReloadAt: number | null,
+  windowMs: number,
+): boolean {
+  if (lastReloadAt === null || Number.isNaN(lastReloadAt)) return true;
+  return now - lastReloadAt > windowMs;
+}
 
 // Heuristic detection of a failed dynamic import. Since the code-splitting work,
 // every route (plus Aside / AiChatWindow) is React.lazy: when a new deploy
@@ -24,12 +42,16 @@ export function isChunkLoadError(error: unknown): boolean {
 function handleError(error: unknown) {
   if (!isChunkLoadError(error)) return;
   // A stale-chunk 404 is cured by a full reload that re-fetches index.html and
-  // the new chunk manifest. Auto-reload once, guarding against a reload loop
-  // (e.g. a genuinely missing chunk) with a one-shot sessionStorage flag. If the
-  // flag is already set we fall through to the manual recovery UI below.
+  // the new chunk manifest. Auto-reload at most once per RELOAD_WINDOW_MS: this
+  // recovers across multiple deploys in a single tab's lifetime, yet a
+  // permanently-broken lazy chunk (which would loop) is stopped after the first
+  // reload and falls through to the manual recovery UI below.
   try {
-    if (sessionStorage.getItem(RELOAD_FLAG)) return;
-    sessionStorage.setItem(RELOAD_FLAG, "1");
+    const raw = sessionStorage.getItem(RELOAD_AT_KEY);
+    const lastReloadAt = raw === null ? null : Number.parseInt(raw, 10);
+    const now = Date.now();
+    if (!shouldAutoReload(now, lastReloadAt, RELOAD_WINDOW_MS)) return;
+    sessionStorage.setItem(RELOAD_AT_KEY, String(now));
   } catch {
     // sessionStorage unavailable (private mode / disabled): skip the automatic
     // reload rather than risk an unguarded loop; the fallback UI still recovers.