Fix localStorage race conditions and error handling in user settings

[Copilot]

Addresses code review feedback on user settings persistence: localStorage operations could fail in restricted environments, async session validation had race conditions, and dead code remained from previous refactoring.

Changes

• Wrap localStorage writes in try/catch (onMutate): Storage access throws in private mode; catch and log without failing the mutation
• Fix validateActiveSession race condition: Remove stale boolean parameter, read isMounted from closure after getSession() completes to prevent cross-user leakage
• Remove unused hasCompletedInitialFetchRef: Dead state from earlier sync logic iteration
• Use getSession() over getUser() (CourseCard): Avoid network request on mount; read cached session

// Before: stale parameter allows state updates after unmount
const validateActiveSession = async (userId: string, isComponentMounted: boolean) => {
  if (!isComponentMounted) return false;
  const { data: { session } } = await supabase.auth.getSession();
  return !!(session?.user.id === userId && isComponentMounted); // stale
};

// After: closure reflects current mount state
const validateActiveSession = async (userId: string) => {
  if (!isMounted) return false; // fresh check
  const { data: { session } } = await supabase.auth.getSession();
  return !!(session?.user.id === userId && isMounted); // fresh recheck
};

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[Copilot]

Pull request overview

Improves robustness of user settings persistence and session validation by hardening storage interactions and removing stale/racy logic around Supabase session checks.

Changes:

• Wraps localStorage writes in try/catch during optimistic updates to avoid failing mutations in restricted storage environments.
• Updates validateActiveSession to avoid stale mount-state parameters and reduce race conditions during async session checks.
• Switches CourseCard from getUser() to getSession() to prefer cached session access and reduce unnecessary network calls.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/providers/user-settings.ts	Adds guarded localStorage writes in onMutate, refactors session validation helper, and removes dead initial-fetch ref logic.
src/components/attendance/course-card.tsx	Uses getSession() instead of getUser() when deriving the scoped localStorage key for bunk calc UI state.

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[Copilot]

The try block wraps both localStorage.setItem and the bunkCalcToggle event dispatch. In environments where setItem throws (private mode / storage disabled), the event will never dispatch, so listeners (e.g. CourseCard) won’t update even though the optimistic cache update succeeded. Consider limiting the try/catch to just the localStorage calls and dispatching the event regardless (or dispatching in a finally after computing the new value).

Suggested change

	try {
	if (newSettings.bunk_calculator_enabled !== undefined) {
	localStorage.setItem(`showBunkCalc_${userId}`, newSettings.bunk_calculator_enabled.toString());
	window.dispatchEvent(new CustomEvent("bunkCalcToggle", { detail: newSettings.bunk_calculator_enabled }));
	}
	if (newSettings.target_percentage !== undefined) {
	const normalizedTarget = normalizeTarget(newSettings.target_percentage);
	localStorage.setItem(`targetPercentage_${userId}`, normalizedTarget.toString());
	}
	} catch (error) {
	// Storage access may throw in private mode or when disabled
	// Log error but don't fail the mutation - DB update can still proceed
	logger.dev("Failed to write to localStorage in onMutate", { error });
	if (newSettings.bunk_calculator_enabled !== undefined) {
	try {
	localStorage.setItem(`showBunkCalc_${userId}`, newSettings.bunk_calculator_enabled.toString());
	} catch (error) {
	// Storage access may throw in private mode or when disabled
	// Log error but don't fail the mutation - DB update can still proceed
	logger.dev("Failed to write bunk_calculator_enabled to localStorage in onMutate", { error });
	}
	// Always notify listeners about bunk calculator toggle, even if localStorage fails
	window.dispatchEvent(new CustomEvent("bunkCalcToggle", { detail: newSettings.bunk_calculator_enabled }));
	}
	if (newSettings.target_percentage !== undefined) {
	const normalizedTarget = normalizeTarget(newSettings.target_percentage);
	try {
	localStorage.setItem(`targetPercentage_${userId}`, normalizedTarget.toString());
	} catch (error) {
	// Storage access may throw in private mode or when disabled
	// Log error but don't fail the mutation - DB update can still proceed
	logger.dev("Failed to write target_percentage to localStorage in onMutate", { error });
	}