Fix all 20 pre-existing type errors; typecheck now green

- ui/chart.tsx: recharts 3 stopped exposing tooltip/legend content props
  on its public types; declare the ChartPayloadItem shape we consume
- base-ui Select onValueChange passes string|null: guard null in
  BillingCycleSelector, PasteImportModal, TransactionModal
- type the untyped api.get calls (cycles, categories)
- push-notifications: back the VAPID key with an explicit ArrayBuffer
  so it satisfies BufferSource under TS 5.9

Unblocks gating CI on pnpm typecheck.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/components/BillingCycleSelector.tsx

@@ -26,7 +26,7 @@ export default function BillingCycleSelector({ value, onChange }: Props) {
   const [cycles, setCycles] = useState<CycleOption[]>([]);
 
   useEffect(() => {
-    api.get('/transactions/cycles').then((r) => setCycles(r.data));
+    api.get<CycleOption[]>('/transactions/cycles').then((r) => setCycles(r.data));
   }, []);
 
   const selectedKey = value ? `${value.year}-${value.month}` : 'all';
@@ -37,7 +37,7 @@ export default function BillingCycleSelector({ value, onChange }: Props) {
       <Select
         value={selectedKey}
         onValueChange={(val) => {
-          if (val === 'all') {
+          if (!val || val === 'all') {
             onChange(null);
           } else {
             const [y, m] = val.split('-').map(Number);

frontend/src/components/PasteImportModal.tsx

@@ -61,7 +61,7 @@ export default function PasteImportModal({ onClose, onImported }: Props) {
             <div className="grid grid-cols-2 gap-4">
               <div className="space-y-2">
                 <Label>Bank</Label>
-                <Select value={bank} onValueChange={setBank}>
+                <Select value={bank} onValueChange={(v) => v && setBank(v)}>
                   <SelectTrigger className="w-full">
                     <SelectValue />
                   </SelectTrigger>
@@ -74,7 +74,7 @@ export default function PasteImportModal({ onClose, onImported }: Props) {
               </div>
               <div className="space-y-2">
                 <Label>Source</Label>
-                <Select value={source} onValueChange={setSource}>
+                <Select value={source} onValueChange={(v) => v && setSource(v)}>
                   <SelectTrigger className="w-full">
                     <SelectValue />
                   </SelectTrigger>

frontend/src/components/TransactionModal.tsx

@@ -48,8 +48,8 @@ export default function TransactionModal({ transaction, source, onClose, onSaved
   const [error, setError] = useState('');
 
   useEffect(() => {
-    api.get('/categories/').then((r) => {
-      const sorted = [...r.data].sort((a: Category, b: Category) => a.name.localeCompare(b.name));
+    api.get<Category[]>('/categories/').then((r) => {
+      const sorted = [...r.data].sort((a, b) => a.name.localeCompare(b.name));
       setCategories(sorted);
     });
   }, []);
@@ -144,7 +144,7 @@ export default function TransactionModal({ transaction, source, onClose, onSaved
             </div>
             <div className="space-y-2">
               <Label>Currency</Label>
-              <Select value={form.currency} onValueChange={(v) => setForm({ ...form, currency: v })}>
+              <Select value={form.currency} onValueChange={(v) => v && setForm({ ...form, currency: v })}>
                 <SelectTrigger className="w-full">
                   <SelectValue />
                 </SelectTrigger>
@@ -166,7 +166,7 @@ export default function TransactionModal({ transaction, source, onClose, onSaved
             </div>
             <div className="space-y-2">
               <Label>Type</Label>
-              <Select value={form.transaction_type} onValueChange={(v) => setForm({ ...form, transaction_type: v })}>
+              <Select value={form.transaction_type} onValueChange={(v) => v && setForm({ ...form, transaction_type: v })}>
                 <SelectTrigger className="w-full">
                   <SelectValue />
                 </SelectTrigger>
@@ -180,7 +180,7 @@ export default function TransactionModal({ transaction, source, onClose, onSaved
               <Label>Category</Label>
               <Select
                 value={form.category_id ? String(form.category_id) : 'auto'}
-                onValueChange={(v) => setForm({ ...form, category_id: v === 'auto' ? '' : v })}
+                onValueChange={(v) => setForm({ ...form, category_id: v && v !== 'auto' ? v : '' })}
               >
                 <SelectTrigger className="w-full">
                   <SelectValue>
@@ -201,7 +201,7 @@ export default function TransactionModal({ transaction, source, onClose, onSaved
             </div>
             <div className="space-y-2">
               <Label>Bank</Label>
-              <Select value={form.bank} onValueChange={(v) => setForm({ ...form, bank: v })}>
+              <Select value={form.bank} onValueChange={(v) => v && setForm({ ...form, bank: v })}>
                 <SelectTrigger className="w-full">
                   <SelectValue />
                 </SelectTrigger>

frontend/src/components/ui/chart.tsx

@@ -104,6 +104,17 @@ ${colorConfig
 
 const ChartTooltip = RechartsPrimitive.Tooltip
 
+// recharts 3 no longer exposes the tooltip/legend content props on its public
+// component types; declare the shape we actually consume.
+type ChartPayloadItem = {
+  dataKey?: string | number
+  name?: string | number
+  value?: number | string
+  color?: string
+  type?: string
+  payload?: Record<string, unknown> & { fill?: string }
+}
+
 function ChartTooltipContent({
   active,
   payload,
@@ -118,8 +129,23 @@ function ChartTooltipContent({
   color,
   nameKey,
   labelKey,
-}: React.ComponentProps<typeof RechartsPrimitive.Tooltip> &
-  React.ComponentProps<"div"> & {
+}: React.ComponentProps<"div"> & {
+    active?: boolean
+    payload?: ChartPayloadItem[]
+    label?: string | number
+    labelFormatter?: (
+      value: string | number,
+      payload: ChartPayloadItem[]
+    ) => React.ReactNode
+    labelClassName?: string
+    formatter?: (
+      value: number | string,
+      name: string | number,
+      item: ChartPayloadItem,
+      index: number,
+      payload: unknown
+    ) => React.ReactNode
+    color?: string
     hideLabel?: boolean
     hideIndicator?: boolean
     indicator?: "line" | "dot" | "dashed"
@@ -144,7 +170,7 @@ function ChartTooltipContent({
     if (labelFormatter) {
       return (
         <div className={cn("font-medium", labelClassName)}>
-          {labelFormatter(value, payload)}
+          {labelFormatter(value as string | number, payload)}
         </div>
       )
     }
@@ -184,7 +210,7 @@ function ChartTooltipContent({
           .map((item, index) => {
             const key = `${nameKey || item.name || item.dataKey || "value"}`
             const itemConfig = getPayloadConfigFromPayload(config, item, key)
-            const indicatorColor = color || item.payload.fill || item.color
+            const indicatorColor = color || item.payload?.fill || item.color
 
             return (
               <div
@@ -258,8 +284,9 @@ function ChartLegendContent({
   payload,
   verticalAlign = "bottom",
   nameKey,
-}: React.ComponentProps<"div"> &
-  Pick<RechartsPrimitive.LegendProps, "payload" | "verticalAlign"> & {
+}: React.ComponentProps<"div"> & {
+    payload?: ChartPayloadItem[]
+    verticalAlign?: "top" | "middle" | "bottom"
     hideIcon?: boolean
     nameKey?: string
   }) {

frontend/src/lib/push-notifications.ts

@@ -1,10 +1,11 @@
 import api from './api';
 
-function urlBase64ToUint8Array(base64String: string): Uint8Array {
+function urlBase64ToUint8Array(base64String: string): Uint8Array<ArrayBuffer> {
   const padding = '='.repeat((4 - (base64String.length % 4)) % 4);
   const base64 = (base64String + padding).replace(/-/g, '+').replace(/_/g, '/');
   const rawData = window.atob(base64);
-  const outputArray = new Uint8Array(rawData.length);
+  // Explicit ArrayBuffer backing so the result satisfies BufferSource.
+  const outputArray = new Uint8Array(new ArrayBuffer(rawData.length));
   for (let i = 0; i < rawData.length; ++i) {
     outputArray[i] = rawData.charCodeAt(i);
   }