diff --git a/client/pages/BillsPage.jsx b/client/pages/BillsPage.tsx
similarity index 87%
rename from client/pages/BillsPage.jsx
rename to client/pages/BillsPage.tsx
index 9f865a0..67d6165 100644
--- a/client/pages/BillsPage.jsx
+++ b/client/pages/BillsPage.tsx
@@ -1,4 +1,4 @@
-import React, { useEffect, useState, useCallback, useMemo, useRef } from 'react';
+import { useEffect, useState, useCallback, useMemo, useRef } from 'react';
 import { useSearchParams } from 'react-router-dom';
 import { useQueryClient } from '@tanstack/react-query';
 import { useBills, useCategories, useBillTemplates, useDeletedBills } from '@/hooks/useQueries';
@@ -20,14 +20,19 @@ import {
   Select, SelectTrigger, SelectValue, SelectContent, SelectItem,
 } from '@/components/ui/select';
 import { api } from '@/api';
-import { cn } from '@/lib/utils';
+import { cn, errMessage } from '@/lib/utils';
 import { useSearchPanelPreference } from '@/hooks/useSearchPanelPreference';
 import { moveInArray, movedItemId, reorderPayload } from '@/lib/reorder';
 import BillsTableInner from '@/components/BillsTableInner';
 import BillModal from '@/components/BillModal';
 import RecentlyDeletedBillsDialog from '@/components/RecentlyDeletedBillsDialog';
-import { makeBillDraft } from '@/lib/billDrafts';
+import { makeBillDraft, type SourceBill } from '@/lib/billDrafts';
 import { scheduleLabel, scheduleValue } from '@/lib/billingSchedule';
+import type { Bill } from '@/types';
+import type { DragProps, MoveControls } from '@/components/tracker/MobileTrackerRow';
+
+interface BuiltInTemplate { id: string; name: string; data: SourceBill; categoryKeywords: string[] }
+interface BillTemplate { id: number | string; name: string; data?: SourceBill; categoryKeywords?: string[] }
 
 const VISIBILITY_OPTIONS = [
   { value: 'default', label: 'Default', description: 'Use the app default behavior for inactive bill history.' },
@@ -35,13 +40,13 @@ const VISIBILITY_OPTIONS = [
   { value: 'none',    label: 'Show no history', description: 'Hide historical tracker data for this inactive bill.' },
   { value: 'ranges',  label: 'Show only selected date ranges', description: 'Show history only for the ranges listed below.' },
 ];
-const MONTH_OPTIONS = [
+const MONTH_OPTIONS: [string, string][] = [
   ['1', 'Jan'], ['2', 'Feb'], ['3', 'Mar'], ['4', 'Apr'], ['5', 'May'], ['6', 'Jun'],
   ['7', 'Jul'], ['8', 'Aug'], ['9', 'Sep'], ['10', 'Oct'], ['11', 'Nov'], ['12', 'Dec'],
 ];
 const FILTER_ALL = 'all';
 
-const BUILT_IN_TEMPLATES = [
+const BUILT_IN_TEMPLATES: BuiltInTemplate[] = [
   {
     id: 'builtin-utility',
     name: 'Utility',
@@ -122,7 +127,26 @@ const BUILT_IN_TEMPLATES = [
 
 // BillModal is imported from @/components/BillModal
 
-function blankRange() {
+interface HistoryRange {
+  id?: number;
+  _key: string;
+  start_year: string;
+  start_month: string;
+  end_year: string;
+  end_month: string;
+  label: string;
+}
+interface RawRange {
+  id?: number;
+  _key?: string;
+  start_year?: number | string | null;
+  start_month?: number | string | null;
+  end_year?: number | string | null;
+  end_month?: number | string | null;
+  label?: string | null;
+}
+
+function blankRange(): HistoryRange {
   const year = String(new Date().getFullYear());
   return {
     _key: `new-${Date.now()}-${Math.random().toString(16).slice(2)}`,
@@ -134,7 +158,7 @@ function blankRange() {
   };
 }
 
-function normalizeRange(range) {
+function normalizeRange(range: RawRange): HistoryRange {
   return {
     ...range,
     _key: range._key || String(range.id),
@@ -146,7 +170,7 @@ function normalizeRange(range) {
   };
 }
 
-function rangePayload(range) {
+function rangePayload(range: HistoryRange) {
   return {
     start_year: parseInt(range.start_year, 10),
     start_month: parseInt(range.start_month, 10),
@@ -156,7 +180,7 @@ function rangePayload(range) {
   };
 }
 
-function validateRange(range) {
+function validateRange(range: HistoryRange): string | null {
   const payload = rangePayload(range);
   if (!Number.isInteger(payload.start_year) || payload.start_year < 2000 || payload.start_year > 2100) {
     return 'Start year must be between 2000 and 2100.';
@@ -167,7 +191,7 @@ function validateRange(range) {
   if ((payload.end_year == null) !== (payload.end_month == null)) {
     return 'End year and end month must both be provided or both left blank.';
   }
-  if (payload.end_year != null) {
+  if (payload.end_year != null && payload.end_month != null) {
     if (payload.end_year < 2000 || payload.end_year > 2100) {
       return 'End year must be between 2000 and 2100.';
     }
@@ -185,7 +209,20 @@ function validateRange(range) {
 
 const PREFS_KEY = 'bills-display-prefs-v1';
 
-const PREFS_DEFAULTS = {
+interface DisplayPrefs {
+  showCategory: boolean;
+  showDueDay: boolean;
+  showAmount: boolean;
+  showCycle: boolean;
+  showApr: boolean;
+  showBalance: boolean;
+  showMinPayment: boolean;
+  showAutopay: boolean;
+  show2fa: boolean;
+  showSubscription: boolean;
+}
+
+const PREFS_DEFAULTS: DisplayPrefs = {
   showCategory:   true,
   showDueDay:     true,
   showAmount:     true,
@@ -198,7 +235,7 @@ const PREFS_DEFAULTS = {
   showSubscription: true,
 };
 
-const PREFS_LABELS = [
+const PREFS_LABELS: [keyof DisplayPrefs, string][] = [
   ['showCategory',     'Category'],
   ['showDueDay',       'Due day'],
   ['showAmount',       'Amount'],
@@ -212,7 +249,7 @@ const PREFS_LABELS = [
 ];
 
 function useDisplayPrefs() {
-  const [prefs, setPrefs] = useState(() => {
+  const [prefs, setPrefs] = useState<DisplayPrefs>(() => {
     try {
       const raw = localStorage.getItem(PREFS_KEY);
       return raw ? { ...PREFS_DEFAULTS, ...JSON.parse(raw) } : PREFS_DEFAULTS;
@@ -221,10 +258,10 @@ function useDisplayPrefs() {
     }
   });
 
-  const toggle = (key) => {
+  const toggle = (key: keyof DisplayPrefs) => {
     setPrefs(prev => {
       const next = { ...prev, [key]: !prev[key] };
-      try { localStorage.setItem(PREFS_KEY, JSON.stringify(next)); } catch {}
+      try { localStorage.setItem(PREFS_KEY, JSON.stringify(next)); } catch { /* ignore quota errors */ }
       return next;
     });
   };
@@ -232,14 +269,14 @@ function useDisplayPrefs() {
   return { prefs, toggle };
 }
 
-function DisplayPrefsPanel({ prefs, onToggle }) {
+function DisplayPrefsPanel({ prefs, onToggle }: { prefs: DisplayPrefs; onToggle: (key: keyof DisplayPrefs) => void }) {
   const [open, setOpen] = useState(false);
-  const ref = useRef(null);
+  const ref = useRef<HTMLDivElement>(null);
 
   useEffect(() => {
     if (!open) return;
-    const handler = (e) => {
-      if (ref.current && !ref.current.contains(e.target)) setOpen(false);
+    const handler = (e: MouseEvent) => {
+      if (ref.current && !ref.current.contains(e.target as Node)) setOpen(false);
     };
     document.addEventListener('mousedown', handler);
     return () => document.removeEventListener('mousedown', handler);
@@ -290,7 +327,7 @@ function DisplayPrefsPanel({ prefs, onToggle }) {
   );
 }
 
-function amountSearchText(...values) {
+function amountSearchText(...values: (number | string | null | undefined)[]): string {
   return values
     .filter(value => value !== null && value !== undefined && Number.isFinite(Number(value)))
     .flatMap(value => {
@@ -300,14 +337,14 @@ function amountSearchText(...values) {
     .join(' ');
 }
 
-function billIsDebt(bill) {
+function billIsDebt(bill: Bill): boolean {
   const category = String(bill.category_name || '').toLowerCase();
   return Number(bill.current_balance) > 0
     || bill.minimum_payment != null
     || ['credit card', 'credit cards', 'loan', 'loans', 'debt', 'mortgage'].some(token => category.includes(token));
 }
 
-function FilterChip({ active, children, onClick }) {
+function FilterChip({ active, children, onClick }: { active: boolean; children: React.ReactNode; onClick: () => void }) {
   return (
     <button
       type="button"
@@ -327,7 +364,7 @@ function FilterChip({ active, children, onClick }) {
 const BILLS_SORT_KEY = 'bills_sort_mode';
 const BILLS_CADENCE_ORDER = ['weekly', 'biweekly', 'monthly', 'quarterly', 'annual', 'other'];
 
-function normalizedBillCadence(bill) {
+function normalizedBillCadence(bill: Bill): string {
   const raw = String(bill?.cycle_type || bill?.billing_cycle || '').toLowerCase();
   if (raw.includes('week') && raw.includes('bi')) return 'biweekly';
   if (raw === 'biweekly') return 'biweekly';
@@ -338,12 +375,12 @@ function normalizedBillCadence(bill) {
   return 'other';
 }
 
-function billCadenceIndex(bill) {
+function billCadenceIndex(bill: Bill): number {
   const index = BILLS_CADENCE_ORDER.indexOf(normalizedBillCadence(bill));
   return index >= 0 ? index : BILLS_CADENCE_ORDER.length - 1;
 }
 
-function sortBillsByCadence(items) {
+function sortBillsByCadence(items: Bill[]): Bill[] {
   return [...items].sort((a, b) => (
     billCadenceIndex(a) - billCadenceIndex(b)
     || (Number(a.due_day) || 0) - (Number(b.due_day) || 0)
@@ -351,7 +388,7 @@ function sortBillsByCadence(items) {
   ));
 }
 
-function SortModeButton({ active, children, onClick }) {
+function SortModeButton({ active, children, onClick }: { active: boolean; children: React.ReactNode; onClick: () => void }) {
   return (
     <button
       type="button"
@@ -371,10 +408,10 @@ function SortModeButton({ active, children, onClick }) {
 
 // ─────────────────────────────────────────────────────────────────────────────
 
-function HistoryVisibilityDialog({ bill, onClose, onSaved }) {
-  const [visibility, setVisibility] = useState(bill?.history_visibility || 'default');
-  const [ranges, setRanges] = useState([]);
-  const [deletedIds, setDeletedIds] = useState([]);
+function HistoryVisibilityDialog({ bill, onClose, onSaved }: { bill: Bill; onClose: () => void; onSaved: () => void }) {
+  const [visibility, setVisibility] = useState<string>((bill?.history_visibility as string) || 'default');
+  const [ranges, setRanges] = useState<HistoryRange[]>([]);
+  const [deletedIds, setDeletedIds] = useState<number[]>([]);
   const [loading, setLoading] = useState(true);
   const [saving, setSaving] = useState(false);
 
@@ -382,25 +419,26 @@ function HistoryVisibilityDialog({ bill, onClose, onSaved }) {
     let mounted = true;
     setLoading(true);
     api.billHistoryRanges(bill.id)
-      .then(data => {
+      .then(raw => {
         if (!mounted) return;
-        setVisibility(data.history_visibility || bill.history_visibility || 'default');
+        const data = raw as { history_visibility?: string; ranges?: RawRange[] };
+        setVisibility(data.history_visibility || (bill.history_visibility as string) || 'default');
         setRanges((data.ranges || []).map(normalizeRange));
       })
       .catch(err => {
-        toast.error(err.message || 'Failed to load history visibility.');
+        toast.error(errMessage(err, 'Failed to load history visibility.'));
         onClose();
       })
-      .finally(() => mounted && setLoading(false));
+      .finally(() => { if (mounted) setLoading(false); });
     return () => { mounted = false; };
   }, [bill, onClose]);
 
-  const updateRange = (key, patch) => {
+  const updateRange = (key: string, patch: Partial<HistoryRange>) => {
     setRanges(prev => prev.map(r => r._key === key ? { ...r, ...patch } : r));
   };
 
-  const deleteRange = (range) => {
-    if (range.id) setDeletedIds(prev => [...prev, range.id]);
+  const deleteRange = (range: HistoryRange) => {
+    if (range.id) setDeletedIds(prev => [...prev, range.id!]);
     setRanges(prev => prev.filter(r => r._key !== range._key));
   };
 
@@ -437,7 +475,7 @@ function HistoryVisibilityDialog({ bill, onClose, onSaved }) {
       onSaved();
       onClose();
     } catch (err) {
-      toast.error(err.message || 'Failed to save history visibility.');
+      toast.error(errMessage(err, 'Failed to save history visibility.'));
     } finally {
       setSaving(false);
     }
@@ -598,6 +636,18 @@ function HistoryVisibilityDialog({ bill, onClose, onSaved }) {
   );
 }
 
+interface ModalState { bill: Bill | null; initialBill?: Partial<Bill> }
+type BoolFilterKey = 'autopay' | 'firstBucket' | 'fifteenthBucket' | 'debt' | 'inactive';
+interface BillFilters {
+  category: string;
+  cycle: string;
+  autopay: boolean;
+  firstBucket: boolean;
+  fifteenthBucket: boolean;
+  debt: boolean;
+  inactive: boolean;
+}
+
 // ── Bills Page ─────────────────────────────────────────────────────────────
 export default function BillsPage() {
   const [searchParams] = useSearchParams();
@@ -607,11 +657,12 @@ export default function BillsPage() {
   // list edits below write to the cache via setQueryData.
   const { data: bills = [], isPending: billsPending } = useBills();
   const { data: categories = [] } = useCategories();
-  const { data: savedTemplates = [] } = useBillTemplates();
+  const { data: savedTemplatesRaw = [] } = useBillTemplates();
+  const savedTemplates = savedTemplatesRaw as BillTemplate[];
   const { data: deletedBills = [] } = useDeletedBills();
   const loading = billsPending;
   const setBills = useCallback(
-    (updater) => queryClient.setQueryData(['bills'], prev => (
+    (updater: Bill[] | ((prev: Bill[]) => Bill[])) => queryClient.setQueryData<Bill[]>(['bills'], prev => (
       typeof updater === 'function' ? updater(prev || []) : updater
     )),
     [queryClient],
@@ -625,10 +676,10 @@ export default function BillsPage() {
   const [showDeleted, setShowDeleted] = useState(false);
   const [showInactive, setShowInactive] = useState(false);
   const [search, setSearch] = useState('');
-  const [draggingId, setDraggingId] = useState(null);
-  const [dropTargetId, setDropTargetId] = useState(null);
-  const [movingBillId, setMovingBillId] = useState(null);
-  const [filters, setFilters] = useState({
+  const [draggingId, setDraggingId] = useState<number | null>(null);
+  const [dropTargetId, setDropTargetId] = useState<number | null>(null);
+  const [movingBillId, setMovingBillId] = useState<number | string | null>(null);
+  const [filters, setFilters] = useState<BillFilters>({
     category: FILTER_ALL,
     cycle: FILTER_ALL,
     autopay: false,
@@ -639,18 +690,18 @@ export default function BillsPage() {
   });
 
   // modal state: null = closed, { bill: null } = add new, { bill: {...} } = edit
-  const [modal,      setModal]      = useState(null);
+  const [modal,      setModal]      = useState<ModalState | null>(null);
   // Bill pending deactivation confirmation (AlertDialog replaces window.confirm)
-  const [deactivate, setDeactivate] = useState(null);
+  const [deactivate, setDeactivate] = useState<Bill | null>(null);
   const [deactivateReason, setDeactivateReason] = useState('');
-  const [deleteTarget, setDeleteTarget] = useState(null);
+  const [deleteTarget, setDeleteTarget] = useState<Bill | null>(null);
   const [deleteConfirmed, setDeleteConfirmed] = useState(false);
   const [deleteBusy, setDeleteBusy] = useState(false);
-  const [historyTarget, setHistoryTarget] = useState(null);
+  const [historyTarget, setHistoryTarget] = useState<Bill | null>(null);
 
   const { prefs, toggle: togglePref } = useDisplayPrefs();
 
-  const [billsSort, setBillsSort] = useState(() => (
+  const [billsSort, setBillsSort] = useState<'custom' | 'cadence'>(() => (
     localStorage.getItem(BILLS_SORT_KEY) === 'cadence' ? 'cadence' : 'custom'
   ));
   const [searchPanelCollapsed, setSearchPanelCollapsed] = useSearchPanelPreference();
@@ -674,8 +725,8 @@ export default function BillsPage() {
     if (filters.inactive) setShowInactive(true);
   }, [filters.inactive]);
 
-  const toggleFilter = (key) => setFilters(prev => ({ ...prev, [key]: !prev[key] }));
-  const setFilterValue = (key, value) => setFilters(prev => ({ ...prev, [key]: value }));
+  const toggleFilter = (key: BoolFilterKey) => setFilters(prev => ({ ...prev, [key]: !prev[key] }));
+  const setFilterValue = (key: 'category' | 'cycle', value: string) => setFilters(prev => ({ ...prev, [key]: value }));
   const hasFilters = !!(
     search.trim()
     || filters.category !== FILTER_ALL
@@ -700,34 +751,34 @@ export default function BillsPage() {
     });
   };
 
-  async function handleEdit(billId) {
+  async function handleEdit(billId: number) {
     try {
       const bill = await api.bill(billId);
       setModal({ bill });
     } catch (err) {
-      toast.error(err.message);
+      toast.error(errMessage(err, 'Failed to load bill'));
     }
   }
 
-  function handleDuplicateBill(bill) {
-    setModal({ bill: null, initialBill: makeBillDraft(bill, { copy: true, categories }) });
+  function handleDuplicateBill(bill: Bill) {
+    setModal({ bill: null, initialBill: makeBillDraft(bill, { copy: true, categories }) as Partial<Bill> });
   }
 
-  function handleTemplateSelect(value) {
+  function handleTemplateSelect(value: string) {
     if (!value || value === 'placeholder') return;
     const builtIn = BUILT_IN_TEMPLATES.find(template => template.id === value);
     if (builtIn) {
-      setModal({ bill: null, initialBill: makeBillDraft(builtIn.data, { template: builtIn, categories }) });
+      setModal({ bill: null, initialBill: makeBillDraft(builtIn.data, { template: builtIn, categories }) as Partial<Bill> });
       return;
     }
 
     const saved = savedTemplates.find(template => `saved-${template.id}` === value);
     if (saved) {
-      setModal({ bill: null, initialBill: makeBillDraft(saved.data, { template: saved, categories }) });
+      setModal({ bill: null, initialBill: makeBillDraft(saved.data, { template: saved, categories }) as Partial<Bill> });
     }
   }
 
-  function handleToggle(bill) {
+  function handleToggle(bill: Bill) {
     if (bill.active) {
       // Prompt confirmation before deactivating
       setDeactivate(bill);
@@ -736,20 +787,20 @@ export default function BillsPage() {
     }
   }
 
-  async function doToggle(bill, reason) {
+  async function doToggle(bill: Bill | null, reason?: string) {
     if (!bill) return;
     try {
-      const payload = { active: bill.active ? 0 : 1 };
+      const payload: { active: number; inactive_reason?: string } = { active: bill.active ? 0 : 1 };
       if (bill.active && reason) payload.inactive_reason = reason;
       await api.updateBill(bill.id, payload);
       toast.success(bill.active ? 'Bill deactivated' : 'Bill activated');
       refresh();
     } catch (err) {
-      toast.error(err.message);
+      toast.error(errMessage(err, 'Failed to update bill'));
     }
   }
 
-  function handleDeleteRequest(bill) {
+  function handleDeleteRequest(bill: Bill) {
     setDeleteConfirmed(false);
     setDeleteTarget(bill);
   }
@@ -771,7 +822,7 @@ export default function BillsPage() {
               toast.success(`"${bill.name}" restored`);
               refresh();
             } catch (err) {
-              toast.error(err.message || 'Failed to restore bill');
+              toast.error(errMessage(err, 'Failed to restore bill'));
             }
           },
         },
@@ -780,19 +831,19 @@ export default function BillsPage() {
       setDeleteConfirmed(false);
       refresh();
     } catch (err) {
-      toast.error(err.message || 'Failed to delete bill');
+      toast.error(errMessage(err, 'Failed to delete bill'));
     } finally {
       setDeleteBusy(false);
     }
   }
 
-  async function handleRestoreDeleted(bill) {
+  async function handleRestoreDeleted(bill: Bill) {
     try {
       await api.restoreBill(bill.id);
       toast.success(`"${bill.name}" restored`);
       await refresh();
     } catch (err) {
-      toast.error(err.message || 'Failed to restore bill');
+      toast.error(errMessage(err, 'Failed to restore bill'));
     }
   }
 
@@ -805,7 +856,7 @@ export default function BillsPage() {
   }
 
   const cycleOptions = useMemo(() => (
-    Array.from(new Set(bills.map(scheduleValue))).sort()
+    Array.from(new Set(bills.map(bill => scheduleValue(bill)))).sort()
   ), [bills]);
 
   const filteredBills = useMemo(() => {
@@ -842,7 +893,7 @@ export default function BillsPage() {
   const sortedActive   = billsSort === 'cadence' ? sortBillsByCadence(active)   : active;
   const sortedInactive = billsSort === 'cadence' ? sortBillsByCadence(inactive) : inactive;
 
-  async function persistBillOrder(nextBills, movedId) {
+  async function persistBillOrder(nextBills: Bill[], movedId: string | number | null) {
     setBills(nextBills);
     setMovingBillId(movedId);
     try {
@@ -850,23 +901,23 @@ export default function BillsPage() {
       toast.success('Bill order saved');
       refresh();
     } catch (err) {
-      toast.error(err.message || 'Failed to save bill order');
+      toast.error(errMessage(err, 'Failed to save bill order'));
       refresh();
     } finally {
       setMovingBillId(null);
     }
   }
 
-  function reorderBillGroup(activeState, orderedGroup) {
+  function reorderBillGroup(activeState: boolean, orderedGroup: Bill[]) {
     const sourceGroup = bills.filter(bill => !!bill.active === activeState);
     const replacements = [...orderedGroup];
     const nextBills = bills.map(bill => (
-      !!bill.active === activeState ? replacements.shift() : bill
+      !!bill.active === activeState ? replacements.shift()! : bill
     ));
     persistBillOrder(nextBills, movedItemId(sourceGroup, orderedGroup));
   }
 
-  function moveControlsForGroup(group, activeState) {
+  function moveControlsForGroup(group: Bill[], activeState: boolean): (bill: Bill, index: number) => MoveControls {
     return (bill, index) => ({
       enabled: reorderEnabled,
       moving: movingBillId === bill.id,
@@ -877,7 +928,7 @@ export default function BillsPage() {
     });
   }
 
-  function dragPropsForGroup(group, activeState) {
+  function dragPropsForGroup(group: Bill[], activeState: boolean): (bill: Bill, index: number) => DragProps {
     return (bill, index) => {
       if (!reorderEnabled) return { draggable: false };
       return {