fix: improve type safety and input validation

- Update activity type casting in backend service for better Prisma compatibility
- Refine currency prop type in web component to prevent type mismatches
- Add accessibility titles to select elements in recurring expense list
- Enhance currency cents input normalization with integer validation in shared types

Fixes #2, #3, #5, #20

Author: Arun-kushwaha007

apps/backend/src/activity/activity.service.ts

@@ -78,7 +78,7 @@ export class ActivityService {
       data: {
         groupId: params.groupId,
         actorUserId: params.actorUserId,
-        type: params.type as never,
+        type: params.type as Prisma.ActivityType,
         entityId: params.entityId,
         metadata: (params.metadata ?? {}) as Prisma.InputJsonValue,
       },

apps/web/src/components/groups/RecurringExpenseList.tsx

@@ -18,7 +18,7 @@ import { useToast } from '../ui/Toaster';
 type RecurringExpenseListProps = {
   recurringExpenses: RecurringExpenseDto[];
   members: GroupMemberSummaryDto[];
-  currency: string;
+  currency: CurrencyCode;
   onChanged?: () => void;
 };
 
@@ -208,6 +208,7 @@ export function RecurringExpenseList({ recurringExpenses, members, currency, onC
                 placeholder="Amount"
               />
               <select
+                title="Category"
                 className="rounded-xl border border-[var(--fs-border)] bg-[var(--fs-card)] p-3 text-sm text-[var(--fs-text-primary)] outline-none focus:border-[var(--fs-primary)]"
                 value={category}
                 onChange={(event) => setCategory(event.target.value as ExpenseCategory | '')}
@@ -220,6 +221,7 @@ export function RecurringExpenseList({ recurringExpenses, members, currency, onC
                 ))}
               </select>
               <select
+                title="Frequency"
                 className="rounded-xl border border-[var(--fs-border)] bg-[var(--fs-card)] p-3 text-sm text-[var(--fs-text-primary)] outline-none focus:border-[var(--fs-primary)]"
                 value={frequency}
                 onChange={(event) => setFrequency(event.target.value as RecurringExpenseFrequency)}
@@ -288,7 +290,7 @@ export function RecurringExpenseList({ recurringExpenses, members, currency, onC
             <div className="mt-3 flex items-center justify-between text-sm">
               <span className="font-medium text-[var(--fs-text-muted)]">Amount</span>
               <span className="text-lg font-extrabold text-[var(--fs-primary)]">
-                {formatCurrencyFromCents(item.totalAmountCents, currency as CurrencyCode)}
+                {formatCurrencyFromCents(item.totalAmountCents, currency)}
               </span>
             </div>
           </>

packages/shared-types/src/index.ts

@@ -24,7 +24,11 @@ function normalizeCentsInput(amountCents: bigint | number | string): string {
     return String(amountCents);
   }
 
-  return amountCents.trim();
+  const trimmed = amountCents.trim();
+  if (!/^-?\d+$/.test(trimmed)) {
+    throw new Error('Currency formatter expects an integer-cent string.');
+  }
+  return trimmed;
 }
 
 /**