fix: 2026-06-09 full-codebase audit hardening

Validation: shared NaN-guarded Zod coercion helpers in schemas/common.ts replace
the raw number|string transform idiom across every schema (the root-cause NaN bug
class); emailOrEmpty + lenient isoDateString/timeString.

Security: roles privilege-escalation closed; refresh-token family revocation on
reuse; TOTP uses config params; read endpoints permission-guarded; received-invoices
gross VAT on all paths; orders-pdf custom-items authz.

Concurrency: $queryRaw SELECT...FOR UPDATE locks in ascending-id order (warehouse
confirm/cancel, attendance lockUserRow); uniqueness checks moved into create
transactions (TOCTOU -> 409); deterministic id tiebreak on second-precision
timestamp ordering (plan resolveCell/resolveGrid, warehouse FIFO).

Frontend: Rules-of-Hooks fixed across ~14 pages + PlanCellModal; UTC-date persisted
fields; dashboard invalidation gaps; stale-closure confirm bugs.

Tooling/tests: ESLint flat config (react-hooks/rules-of-hooks = error) + Prettier;
tsconfig.test.json so tsc -b type-checks the tests; removed 3 dead deps; npm audit
fix (8 -> 3). Suite 195 -> 247 (happy-path auth, FIFO oldest-first, flakiness fixes),
isolated on app_test via .env.test with a hard-throw setup guard.

Gates: tsc 0 | build 0 | vitest 247/247 | eslint 0 errors.

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

src/context/ThemeContext.tsx

@@ -2,6 +2,7 @@ import {
   createContext,
   useContext,
   useState,
+  useEffect,
   useLayoutEffect,
   type ReactNode,
 } from "react";
@@ -12,22 +13,40 @@ interface ThemeContextValue {
   toggleTheme: () => void;
 }
 
+export type ThemeMode = "light" | "dark";
+
+/**
+ * The first-paint theme fallback used before any stored preference is read.
+ *
+ * SINGLE SOURCE OF TRUTH for the default mode. `MuiProvider`'s
+ * `<ThemeProvider defaultMode="…">` MUST use this same value (import it from
+ * here) — if the two defaults drift, MUI and this context pick different modes
+ * on the first frame and the page/toggle desync until a reload. The two
+ * `localStorage.getItem("mui-mode")` fallbacks below both reference this so
+ * they can never diverge from each other either.
+ */
+export const DEFAULT_THEME_MODE: ThemeMode = "dark";
+
 const ThemeContext = createContext<ThemeContextValue | null>(null);
 
+function readStoredTheme(): ThemeMode {
+  // Single source of truth = MUI's own mode key. MUI's cssVariables provider
+  // reads `mui-mode` on mount and sets `data-theme` from it, so we read/write
+  // that SAME key (no separate boha-theme) — page and toggle stay in sync
+  // across reloads. Fall back to the legacy key for pre-existing sessions.
+  const stored =
+    localStorage.getItem("mui-mode") || localStorage.getItem("boha-theme");
+  return stored === "light" || stored === "dark" ? stored : DEFAULT_THEME_MODE;
+}
+
 type ViewTransitionDocument = Document & {
   startViewTransition?: (callback: () => void) => unknown;
 };
 
 export function ThemeProvider({ children }: { children: ReactNode }) {
-  const [theme, setTheme] = useState(() => {
-    if (typeof window === "undefined") return "dark";
-    // Single source of truth = MUI's own mode key. MUI's cssVariables provider
-    // reads `mui-mode` on mount and sets `data-theme` from it, so we read/write
-    // that SAME key (no separate boha-theme) — page and toggle stay in sync
-    // across reloads. Fall back to the legacy key for pre-existing sessions.
-    const stored =
-      localStorage.getItem("mui-mode") || localStorage.getItem("boha-theme");
-    return stored === "light" || stored === "dark" ? stored : "dark";
+  const [theme, setTheme] = useState<ThemeMode>(() => {
+    if (typeof window === "undefined") return DEFAULT_THEME_MODE;
+    return readStoredTheme();
   });
 
   // Apply synchronously (layout effect) so the `data-theme` attribute flips
@@ -43,6 +62,22 @@ export function ThemeProvider({ children }: { children: ReactNode }) {
       ?.setAttribute("content", themeColor);
   }, [theme]);
 
+  // Cross-tab sync: when another tab toggles the theme it writes `mui-mode`,
+  // which fires a `storage` event here. Mirror the new value (instant — no
+  // View Transition, since this tab didn't initiate the change) so all open
+  // tabs stay visually consistent without a reload.
+  useEffect(() => {
+    const onStorage = (e: StorageEvent) => {
+      if (e.key !== "mui-mode") return;
+      const next = e.newValue;
+      if (next === "light" || next === "dark") {
+        setTheme((prev) => (prev === next ? prev : next));
+      }
+    };
+    window.addEventListener("storage", onStorage);
+    return () => window.removeEventListener("storage", onStorage);
+  }, []);
+
   const toggleTheme = () => {
     const apply = () =>
       setTheme((prev) => (prev === "dark" ? "light" : "dark"));