diff --git a/routes/bills.js b/routes/bills.js
index 1122cc8..84747c4 100644
--- a/routes/bills.js
+++ b/routes/bills.js
@@ -11,7 +11,7 @@ const {
   validateBillData,
   computeBalanceDelta,
   applyBalanceDelta,
-} = require('../services/billsService');
+} = require('../services/billsService.cts');
 const { amortizationSchedule, debtAprSnapshot } = require('../services/aprService.cts');
 const { standardizeError } = require('../middleware/errorFormatter');
 const { validatePaymentInput, serializePayment } = require('../services/paymentValidation.cts');
diff --git a/routes/notifications.js b/routes/notifications.js
index f0d67cf..a15b3f7 100644
--- a/routes/notifications.js
+++ b/routes/notifications.js
@@ -2,8 +2,8 @@ const express = require('express');
 const router  = express.Router();
 const { getDb, getSetting, setSetting } = require('../db/database');
 const { requireAuth, requireUser, requireAdmin } = require('../middleware/requireAuth');
-const { sendTestEmail } = require('../services/notificationService');
-const { sendTestPush }  = require('../services/notificationService')._push || {};
+const { sendTestEmail } = require('../services/notificationService.cts');
+const { sendTestPush }  = require('../services/notificationService.cts')._push || {};
 const { decryptSecret } = require('../services/encryptionService.cts');
 const { encryptSecret } = require('../services/encryptionService.cts');
 
diff --git a/routes/payments.js b/routes/payments.js
index 9379236..92cca7b 100644
--- a/routes/payments.js
+++ b/routes/payments.js
@@ -2,7 +2,7 @@ const express = require('express');
 const { standardizeError } = require('../middleware/errorFormatter');
 const router  = require('express').Router();
 const { getDb } = require('../db/database');
-const { computeBalanceDelta, applyBalanceDelta } = require('../services/billsService');
+const { computeBalanceDelta, applyBalanceDelta } = require('../services/billsService.cts');
 const { validatePaymentInput, serializePayment } = require('../services/paymentValidation.cts');
 const { getCycleRange, resolveDueDate } = require('../services/statusService.cts');
 const { markUnmatched } = require('../services/transactionMatchState.cts');
diff --git a/routes/snowball.js b/routes/snowball.js
index d2b4aea..89626bd 100644
--- a/routes/snowball.js
+++ b/routes/snowball.js
@@ -4,7 +4,7 @@ const { getDb } = require('../db/database');
 const { standardizeError } = require('../middleware/errorFormatter');
 const { calculateSnowball, calculateAvalanche } = require('../services/snowballService.cts');
 const { calculateMinimumOnly, debtAprSnapshot } = require('../services/aprService.cts');
-const { serializeBill } = require('../services/billsService');
+const { serializeBill } = require('../services/billsService.cts');
 const { toCents, fromCents } = require('../utils/money.mts');
 
 const DEBT_LIKE_CLAUSES = `(
diff --git a/services/authService.cts b/services/authService.cts
index 172dce1..3e1d7bd 100644
--- a/services/authService.cts
+++ b/services/authService.cts
@@ -295,7 +295,7 @@ function recordLogin(userId: any, ipAddress: any, userAgent: any, sessionId: any
         !priorFingerprints.includes(device.device_fingerprint);
       if (isNewDevice) {
         try {
-          const { sendPushToUser } = require('./notificationService')._push;
+          const { sendPushToUser } = require('./notificationService.cts')._push;
           const alertUser = getDb().prepare('SELECT * FROM users WHERE id = ?').get(userId);
           if (alertUser?.notify_push_enabled && alertUser?.push_channel) {
             const deviceDesc = [device.browser, device.os, device.device_type !== 'desktop' ? device.device_type : null]
diff --git a/services/billsService.js b/services/billsService.cts
similarity index 89%
rename from services/billsService.js
rename to services/billsService.cts
index a36c1bc..71d1172 100644
--- a/services/billsService.js
+++ b/services/billsService.cts
@@ -1,5 +1,10 @@
+import type { Db } from '../types/db';
 const { monthKey } = require('../utils/dates.mts');
-const { toCents, fromCents } = require('../utils/money.mts');
+const { toCents, fromCents } = require('../utils/money.mts') as typeof import('../utils/money.mts');
+
+type Row = Record<string, any>;
+type FieldResult<T> = { value?: T; error?: string };
+
 const VALID_VISIBILITY = ['default', 'all', 'ranges', 'none'];
 
 const TEMPLATE_FIELDS = [
@@ -11,18 +16,18 @@ const TEMPLATE_FIELDS = [
   'subscription_type', 'reminder_days_before', 'subscription_source', 'subscription_detected_at',
 ];
 
-function hasText(value) {
+function hasText(value: unknown): boolean {
   return typeof value === 'string' && value.trim().length > 0;
 }
 
-function isDebtBill(bill) {
+function isDebtBill(bill: Row): 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'].some(token => category.includes(token));
 }
 
-function billAuditIssue(bill, field, severity, suggestion) {
+function billAuditIssue(bill: Row, field: string, severity: string, suggestion: string) {
   return {
     bill_id: bill.id,
     bill_name: bill.name,
@@ -32,14 +37,14 @@ function billAuditIssue(bill, field, severity, suggestion) {
   };
 }
 
-function sanitizeTemplateData(data = {}) {
-  return TEMPLATE_FIELDS.reduce((out, field) => {
+function sanitizeTemplateData(data: Row = {}): Row {
+  return TEMPLATE_FIELDS.reduce((out: Row, field: string) => {
     if (data[field] !== undefined) out[field] = data[field];
     return out;
-  }, {});
+  }, {} as Row);
 }
 
-function parseTemplateData(raw) {
+function parseTemplateData(raw: any): Row {
   try {
     return sanitizeTemplateData(JSON.parse(raw || '{}'));
   } catch {
@@ -47,7 +52,7 @@ function parseTemplateData(raw) {
   }
 }
 
-function categoryBelongsToUser(db, categoryId, userId) {
+function categoryBelongsToUser(db: Db, categoryId: any, userId: number): boolean {
   if (!categoryId) return true;
   return !!db.prepare('SELECT id FROM categories WHERE id = ? AND user_id = ? AND deleted_at IS NULL').get(categoryId, userId);
 }
@@ -55,7 +60,7 @@ function categoryBelongsToUser(db, categoryId, userId) {
 /**
  * Converts a bill row's integer-cents money columns to dollars for API responses.
  */
-function serializeBill(bill) {
+function serializeBill(bill: Row | null | undefined): any {
   if (!bill) return bill;
   return {
     ...bill,
@@ -65,7 +70,7 @@ function serializeBill(bill) {
   };
 }
 
-function insertBill(db, userId, normalized) {
+function insertBill(db: Db, userId: number, normalized: Row): Row {
   const result = db.prepare(`
     INSERT INTO bills
       (user_id, name, category_id, due_day, override_due_date, bucket, expected_amount,
@@ -110,7 +115,7 @@ function insertBill(db, userId, normalized) {
   return db.prepare('SELECT * FROM bills WHERE id = ?').get(result.lastInsertRowid);
 }
 
-function auditBillsForUser(db, userId, includeInactive = false) {
+function auditBillsForUser(db: Db, userId: number, includeInactive = false) {
   const bills = db.prepare(`
     SELECT b.id, b.name, b.category_id, b.due_day, b.active, b.autopay_enabled,
            b.website, b.username, b.account_info, b.current_balance,
@@ -123,8 +128,8 @@ function auditBillsForUser(db, userId, includeInactive = false) {
     ORDER BY b.active DESC, b.due_day ASC, b.name ASC
   `).all(userId);
 
-  const auditedBills = bills.map((bill) => {
-    const issues = [];
+  const auditedBills = bills.map((bill: Row) => {
+    const issues: any[] = [];
     const dueDay = Number(bill.due_day);
     const debt = isDebtBill(bill);
     const balance = Number(bill.current_balance);
@@ -156,20 +161,20 @@ function auditBillsForUser(db, userId, includeInactive = false) {
     };
   });
 
-  const issues = auditedBills.flatMap(bill => bill.issues);
+  const issues = auditedBills.flatMap((bill: Row) => bill.issues);
   return {
-    bills: auditedBills.filter(bill => bill.issues.length > 0),
+    bills: auditedBills.filter((bill: Row) => bill.issues.length > 0),
     summary: {
       audited_bills: bills.length,
       issue_count: issues.length,
-      error_count: issues.filter(item => item.severity === 'error').length,
-      warning_count: issues.filter(item => item.severity === 'warning').length,
+      error_count: issues.filter((item: Row) => item.severity === 'error').length,
+      warning_count: issues.filter((item: Row) => item.severity === 'warning').length,
     },
   };
 }
 
 // Helper function to get default cycle day based on cycle type
-function getDefaultCycleDay(cycleType) {
+function getDefaultCycleDay(cycleType: any): string {
   switch (cycleType) {
     case 'monthly':
       return '1'; // 1st of the month
@@ -187,7 +192,7 @@ function getDefaultCycleDay(cycleType) {
 }
 
 // Validate cycle_day based on cycle_type
-function validateCycleDay(cycleType, cycleDay) {
+function validateCycleDay(cycleType: any, cycleDay: any): FieldResult<string> {
   if (cycleDay === undefined || cycleDay === null) return { value: getDefaultCycleDay(cycleType) };
   const ct = cycleType || 'monthly';
   switch (ct) {
@@ -213,7 +218,7 @@ function validateCycleDay(cycleType, cycleDay) {
   }
 }
 
-function parseDueDay(value) {
+function parseDueDay(value: any): FieldResult<number> {
   const day = Number(value);
   if (!Number.isInteger(day) || day < 1 || day > 31) {
     return { error: 'due_day must be an integer between 1 and 31' };
@@ -221,7 +226,7 @@ function parseDueDay(value) {
   return { value: day };
 }
 
-function parseInterestRate(value) {
+function parseInterestRate(value: any): FieldResult<number | null> {
   if (value === undefined) return { value: undefined };
   if (value === null) return { value: null };
   if (typeof value === 'string' && value.trim() === '') return { value: null };
@@ -233,18 +238,18 @@ function parseInterestRate(value) {
   return { value: rate };
 }
 
-function getValidCycleTypes() {
+function getValidCycleTypes(): string[] {
   return ['monthly', 'weekly', 'biweekly', 'quarterly', 'annual'];
 }
 
-function cycleTypeFromBillingCycle(billingCycle) {
+function cycleTypeFromBillingCycle(billingCycle: any): string {
   const value = String(billingCycle || '').toLowerCase();
   if (value === 'quarterly') return 'quarterly';
   if (value === 'annually' || value === 'annual') return 'annual';
   return 'monthly';
 }
 
-function billingCycleForCycleType(cycleType) {
+function billingCycleForCycleType(cycleType: any): string {
   const value = String(cycleType || '').toLowerCase();
   if (value === 'quarterly') return 'quarterly';
   if (value === 'annual') return 'annually';
@@ -254,11 +259,10 @@ function billingCycleForCycleType(cycleType) {
 
 /**
  * Validates and normalizes bill data for creation/update.
- * Returns an object with normalized values and any validation errors.
  */
-function validateBillData(data, existingBill = null) {
-  const errors = [];
-  const normalized = {};
+function validateBillData(data: Row, existingBill: Row | null = null) {
+  const errors: any[] = [];
+  const normalized: Row = {};
 
   const validCycleTypes = getValidCycleTypes();
 
@@ -293,7 +297,6 @@ function validateBillData(data, existingBill = null) {
 
   // expected_amount (stored as integer cents). Validate: reject non-numeric,
   // negative, or absurd values (kept well under Number.MAX_SAFE_INTEGER cents).
-  // QA-B13-01: previously any coercible value was accepted ("abc"→$0, -100, 1e15).
   const MAX_EXPECTED_CENTS = 100_000_000_00; // $100,000,000
   if (data.expected_amount === undefined) {
     normalized.expected_amount = existingBill?.expected_amount || 0;
@@ -301,7 +304,7 @@ function validateBillData(data, existingBill = null) {
     normalized.expected_amount = 0;
   } else {
     const cents = toCents(data.expected_amount);
-    if (!Number.isInteger(cents) || cents < 0 || cents > MAX_EXPECTED_CENTS) {
+    if (!Number.isInteger(cents) || cents! < 0 || cents! > MAX_EXPECTED_CENTS) {
       errors.push({ field: 'expected_amount', message: 'expected_amount must be a number between 0 and 100000000' });
     } else {
       normalized.expected_amount = cents;
@@ -394,7 +397,7 @@ function validateBillData(data, existingBill = null) {
       normalized.current_balance = null;
     } else {
       const cb = toCents(data.current_balance);
-      if (!Number.isInteger(cb) || cb < 0) {
+      if (!Number.isInteger(cb) || cb! < 0) {
         errors.push({ field: 'current_balance', message: 'current_balance must be a non-negative number' });
       } else {
         normalized.current_balance = cb;
@@ -410,7 +413,7 @@ function validateBillData(data, existingBill = null) {
       normalized.minimum_payment = null;
     } else {
       const mp = toCents(data.minimum_payment);
-      if (!Number.isInteger(mp) || mp < 0) {
+      if (!Number.isInteger(mp) || mp! < 0) {
         errors.push({ field: 'minimum_payment', message: 'minimum_payment must be a non-negative number' });
       } else {
         normalized.minimum_payment = mp;
@@ -486,20 +489,12 @@ function validateBillData(data, existingBill = null) {
 /**
  * Validates cycle_day for a given cycle_type without requiring the full bill data.
  */
-function validateCycleDayOnly(cycleType, cycleDay) {
+function validateCycleDayOnly(cycleType: any, cycleDay: any) {
   return validateCycleDay(cycleType, cycleDay);
 }
 
 // Computes how a payment affects a debt bill's current_balance.
-// Interest is applied at most once per calendar month: if bill.interest_accrued_month
-// already equals the current month, no interest is added this call.
-//
-// Returns null when the bill has no trackable balance.
-// Otherwise returns:
-//   { new_balance, balance_delta, interest_delta, interest_accrued_month }
-// where interest_delta and interest_accrued_month are null when no interest
-// was charged this call (so callers can use COALESCE to leave the DB column alone).
-function computeBalanceDelta(bill, paymentAmount) {
+function computeBalanceDelta(bill: Row, paymentAmount: any) {
   const bal  = Number(bill.current_balance); // cents
   const rate = Number(bill.interest_rate) || 0; // percent
   const amt  = Number(paymentAmount); // cents
@@ -523,9 +518,8 @@ function computeBalanceDelta(bill, paymentAmount) {
   };
 }
 
-// Updates current_balance (and interest_accrued_month when interest was charged)
-// after a payment. Uses COALESCE so a null interest_accrued_month leaves the column alone.
-function applyBalanceDelta(db, billId, balCalc) {
+// Updates current_balance (and interest_accrued_month when interest was charged) after a payment.
+function applyBalanceDelta(db: Db, billId: any, balCalc: any): void {
   if (!balCalc) return;
   db.prepare(`
     UPDATE bills
diff --git a/services/notificationService.js b/services/notificationService.cts
similarity index 81%
rename from services/notificationService.js
rename to services/notificationService.cts
index f61942f..fb9d172 100644
--- a/services/notificationService.js
+++ b/services/notificationService.cts
@@ -1,3 +1,5 @@
+import type { Db } from '../types/db';
+
 const nodemailer = require('nodemailer');
 const { getDb, getSetting } = require('../db/database');
 const { decryptSecret, encryptSecret } = require('./encryptionService.cts');
@@ -7,22 +9,24 @@ const {
   markNotificationSuccess,
   markNotificationTestSuccess,
 } = require('./statusRuntime.cts');
-const { localDateString } = require('../utils/dates.mts');
-const { fromCents } = require('../utils/money.mts');
+const { localDateString } = require('../utils/dates.mts') as typeof import('../utils/dates.mts');
+const { fromCents } = require('../utils/money.mts') as typeof import('../utils/money.mts');
+
+type Row = Record<string, any>;
 
 // ── Push notification channels ────────────────────────────────────────────────
 
-const PUSH_PRIORITY = { upcoming: 'default', soon: 'high', today: 'high', overdue: 'urgent' };
-const PUSH_TAGS     = { upcoming: ['bell'], soon: ['warning'], today: ['rotating_light'], overdue: ['rotating_light','red_circle'] };
-const DISCORD_COLOR = { upcoming: 0x4f46e5, soon: 0xd97706, today: 0xdc7308, overdue: 0xdc2626 };
+const PUSH_PRIORITY: Record<string, string> = { upcoming: 'default', soon: 'high', today: 'high', overdue: 'urgent' };
+const PUSH_TAGS: Record<string, string[]>   = { upcoming: ['bell'], soon: ['warning'], today: ['rotating_light'], overdue: ['rotating_light','red_circle'] };
+const DISCORD_COLOR: Record<string, number> = { upcoming: 0x4f46e5, soon: 0xd97706, today: 0xdc7308, overdue: 0xdc2626 };
 
-function safeDecrypt(stored) {
+function safeDecrypt(stored: any): string {
   if (!stored) return '';
   try { return decryptSecret(stored); } catch { return stored; }
 }
 
-async function sendNtfy(url, token, title, body, urgency = 'soon') {
-  const headers = {
+async function sendNtfy(url: string, token: any, title: string, body: string, urgency = 'soon') {
+  const headers: Record<string, string> = {
     'Title':    title,
     'Priority': PUSH_PRIORITY[urgency] || 'default',
     'Tags':     (PUSH_TAGS[urgency] || ['bell']).join(','),
@@ -33,8 +37,8 @@ async function sendNtfy(url, token, title, body, urgency = 'soon') {
   if (!res.ok) throw new Error(`ntfy returned ${res.status}`);
 }
 
-async function sendGotify(url, token, title, body, urgency = 'soon') {
-  const priority = { upcoming: 4, soon: 6, today: 7, overdue: 9 }[urgency] ?? 5;
+async function sendGotify(url: string, token: any, title: string, body: string, urgency = 'soon') {
+  const priority = (({ upcoming: 4, soon: 6, today: 7, overdue: 9 } as Record<string, number>)[urgency]) ?? 5;
   const endpoint = url.replace(/\/$/, '') + '/message?token=' + encodeURIComponent(token);
   const res = await fetch(endpoint, {
     method:  'POST',
@@ -44,7 +48,7 @@ async function sendGotify(url, token, title, body, urgency = 'soon') {
   if (!res.ok) throw new Error(`Gotify returned ${res.status}`);
 }
 
-async function sendDiscord(webhookUrl, title, body, urgency = 'soon') {
+async function sendDiscord(webhookUrl: string, title: string, body: string, urgency = 'soon') {
   const color = DISCORD_COLOR[urgency] ?? 0x4f46e5;
   const res = await fetch(webhookUrl, {
     method:  'POST',
@@ -58,7 +62,7 @@ async function sendDiscord(webhookUrl, title, body, urgency = 'soon') {
   if (!res.ok) throw new Error(`Discord returned ${res.status}`);
 }
 
-async function sendTelegram(botToken, chatId, title, body) {
+async function sendTelegram(botToken: any, chatId: any, title: string, body: string) {
   const text = `*${title}*\n${body}`;
   const url  = `https://api.telegram.org/bot${botToken}/sendMessage`;
   const res  = await fetch(url, {
@@ -67,13 +71,13 @@ async function sendTelegram(botToken, chatId, title, body) {
     body:    JSON.stringify({ chat_id: chatId, text, parse_mode: 'Markdown' }),
   });
   if (!res.ok) {
-    const err = await res.json().catch(() => ({}));
+    const err: any = await res.json().catch(() => ({}));
     throw new Error(`Telegram error: ${err.description || res.status}`);
   }
 }
 
 // Dispatch push to whichever channel this user has configured.
-async function sendPushToUser(user, title, body, urgency) {
+async function sendPushToUser(user: Row, title: string, body: string, urgency: any) {
   if (!user.notify_push_enabled || !user.push_channel || !user.push_url) return;
   const url   = safeDecrypt(user.push_url);
   const token = safeDecrypt(user.push_token);
@@ -86,7 +90,7 @@ async function sendPushToUser(user, title, body, urgency) {
   }
 }
 
-async function sendTestPush(user) {
+async function sendTestPush(user: Row) {
   await sendPushToUser(
     user,
     'Bill Tracker — Test Notification',
@@ -95,12 +99,9 @@ async function sendTestPush(user) {
   );
 }
 
-// NOTE: the `_push` export is attached AFTER the final `module.exports = {…}`
-// below — assigning it here would be clobbered by that reassignment (QA-B10-01).
-
 // ── SMTP transport ────────────────────────────────────────────────────────────
 
-function getSmtpPassword() {
+function getSmtpPassword(): string {
   const stored = getSetting('notify_smtp_password');
   if (!stored) return '';
   try {
@@ -110,7 +111,7 @@ function getSmtpPassword() {
   }
 }
 
-function createTransport() {
+function createTransport(): any {
   const host       = getSetting('notify_smtp_host');
   const port       = parseInt(getSetting('notify_smtp_port') || '587', 10);
   const encryption = getSetting('notify_smtp_encryption') || 'starttls';
@@ -132,7 +133,7 @@ function createTransport() {
   });
 }
 
-function senderAddress() {
+function senderAddress(): string {
   const name    = getSetting('notify_sender_name') || 'Bill Tracker';
   const address = getSetting('notify_sender_address');
   if (!address) throw new Error('Sender address is not configured');
@@ -141,19 +142,11 @@ function senderAddress() {
 
 // ── Email templates ───────────────────────────────────────────────────────────
 
-// Per-bill reminder lead time (days before due) for the early "due soon"
-// reminder. Every bill has a reminder_days_before column (default 3); honor it
-// so a user who asks for "7 days before" actually gets a 7-day reminder.
-function leadDaysOf(bill) {
+function leadDaysOf(bill: any): number {
   return Number.isInteger(bill?.reminder_days_before) ? bill.reminder_days_before : 3;
 }
 
-// Which reminder type (if any) applies to a bill that is `diffDays` calendar
-// days from its due date. Pure + exported so the lead-time logic is unit-testable
-// without invoking the full runner (which uses the real clock + real senders).
-// The early reminder fires at the bill's own lead time, and only when that lead
-// is ≥ 2 so it never collides with the 1-day or same-day reminders.
-function reminderTypeFor(bill, diffDays) {
+function reminderTypeFor(bill: any, diffDays: number): string | null {
   const leadDays = leadDaysOf(bill);
   if (diffDays >= 2 && diffDays === leadDays) return 'due_3d';
   if (diffDays === 1) return 'due_1d';
@@ -162,37 +155,33 @@ function reminderTypeFor(bill, diffDays) {
   return null;
 }
 
-const TYPE_META = {
-  // The `due_3d` key is the early reminder; its lead time is the bill's own
-  // reminder_days_before (only fires when that is ≥ 2 — a 1-day lead is covered
-  // by due_1d and a 0-day lead by due_today).
+const TYPE_META: Record<string, { subject: (b: any) => string; urgency: string }> = {
   due_3d:    { subject: (b) => `Reminder: ${b.name} due in ${leadDaysOf(b)} days`, urgency: 'upcoming' },
   due_1d:    { subject: (b) => `Reminder: ${b.name} due tomorrow`,        urgency: 'soon'     },
   due_today: { subject: (b) => `Due today: ${b.name}`,                    urgency: 'today'    },
   overdue:   { subject: (b) => `Overdue: ${b.name} hasn't been paid`,     urgency: 'overdue'  },
 };
 
-const URGENCY_COLOR = {
+const URGENCY_COLOR: Record<string, string> = {
   upcoming: '#4f46e5',
   soon:     '#d97706',
   today:    '#dc7308',
   overdue:  '#dc2626',
 };
 
-function buildEmailHtml(bill, type, dueDate) {
+function buildEmailHtml(bill: Row, type: string, dueDate: any): string {
   const meta   = TYPE_META[type];
   const color  = URGENCY_COLOR[meta.urgency];
   const amount = '$' + (fromCents(bill.expected_amount) || 0).toFixed(2);
-  const fmt    = (d) => {
+  const fmt    = (d: any) => {
     if (!d) return '—';
     const [y, m, day] = d.split('-');
     return `${parseInt(m)}/${parseInt(day)}/${y}`;
   };
 
-  // QA-B14-04: escape the bill name everywhere it lands in the HTML, including
-  // these message strings (previously raw — an XSS vector via the bill name).
+  // QA-B14-04: escape the bill name everywhere it lands in the HTML.
   const name = esc(bill.name);
-  const messages = {
+  const messages: Record<string, string> = {
     due_3d:    `<strong>${name}</strong> is due in ${leadDaysOf(bill)} days.`,
     due_1d:    `<strong>${name}</strong> is due <strong>tomorrow</strong>.`,
     due_today: `<strong>${name}</strong> is due <strong>today</strong>.`,
@@ -242,18 +231,18 @@ function buildEmailHtml(bill, type, dueDate) {
 </html>`;
 }
 
-function esc(s) {
+function esc(s: any): string {
   return String(s || '').replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
 }
 
 // ── Send ──────────────────────────────────────────────────────────────────────
 
-async function sendEmail(to, subject, html) {
+async function sendEmail(to: any, subject: string, html: string) {
   const transport = createTransport();
   await transport.sendMail({ from: senderAddress(), to, subject, html });
 }
 
-async function sendTestEmail(to) {
+async function sendTestEmail(to: any) {
   const html = `<!DOCTYPE html>
 <html><body style="font-family:sans-serif;padding:32px;">
   <h2 style="color:#4f46e5;">Bill Tracker — Test Email</h2>
@@ -271,14 +260,14 @@ async function sendTestEmail(to) {
 
 // ── Notification tracking ─────────────────────────────────────────────────────
 
-function hasNotification(db, billId, userId, year, month, type, date) {
+function hasNotification(db: Db, billId: any, userId: any, year: number, month: number, type: string, date: string): boolean {
   return !!db.prepare(`
     SELECT 1 FROM notifications
     WHERE bill_id=? AND user_id=? AND year=? AND month=? AND type=? AND sent_date=?
   `).get(billId, userId, year, month, type, date);
 }
 
-function recordNotification(db, billId, userId, year, month, type, date) {
+function recordNotification(db: Db, billId: any, userId: any, year: number, month: number, type: string, date: string): void {
   try {
     db.prepare(`
       INSERT INTO notifications (bill_id, user_id, year, month, type, sent_date)
@@ -292,7 +281,7 @@ function recordNotification(db, billId, userId, year, month, type, date) {
 // ── Main notification runner (called by daily worker) ─────────────────────────
 
 async function runNotifications() {
-  const db = getDb();
+  const db: Db = getDb();
 
   const emailReady = getSetting('notify_smtp_enabled') === 'true'
     && !!getSetting('notify_smtp_host')
@@ -313,15 +302,12 @@ async function runNotifications() {
 
   const { getCycleRange, resolveDueDate } = require('./statusService.cts');
 
-  // Fetch all active bills. In global-notification mode, the single global recipient
-  // legitimately receives every bill. In per-user mode, each recipient must only
-  // see their own bills — the ownership filter is applied in the loop below.
   const bills = db.prepare('SELECT * FROM bills WHERE active = 1 AND deleted_at IS NULL').all();
   const allowUserConfig = getSetting('notify_allow_user_config') === 'true';
   const globalRecipient = getSetting('notify_global_recipient');
 
   // Gather recipient list
-  const recipients = [];
+  const recipients: any[] = [];
 
   if (allowUserConfig) {
     const users = db.prepare(
@@ -329,7 +315,6 @@ async function runNotifications() {
     ).all();
     recipients.push(...users);
   } else if (globalRecipient) {
-    // Treat global recipient as a synthetic user-like object
     recipients.push({
       id: 0, notification_email: globalRecipient,
       notify_3d: 1, notify_1d: 1, notify_due: 1, notify_overdue: 1,
@@ -338,15 +323,12 @@ async function runNotifications() {
 
   if (!recipients.length) return;
 
-  const errors = [];
+  const errors: any[] = [];
 
-  // Batch-fetch all payments for active bills this cycle to avoid N+1 queries.
-  // Bills use different cycle ranges per bill, so we use a broad month window
-  // and the per-bill cycle check happens in memory below.
-  const billIds = bills.map(b => b.id);
+  const billIds = bills.map((b: Row) => b.id);
   const monthStart = `${year}-${String(month).padStart(2, '0')}-01`;
   const monthEnd   = localDateString(new Date(year, month, 0));
-  const paidMap = new Map();
+  const paidMap = new Map<any, any>();
   if (billIds.length > 0) {
     const placeholders = billIds.map(() => '?').join(',');
     const paidRows = db.prepare(`
@@ -361,12 +343,11 @@ async function runNotifications() {
     for (const row of paidRows) paidMap.set(row.bill_id, row.paid_sum);
   }
 
-  // Batch-fetch all notifications already sent today to avoid N×M per-bill-per-recipient queries.
   const sentRows = db.prepare(`
     SELECT bill_id, user_id, type FROM notifications
     WHERE year = ? AND month = ? AND sent_date = ?
   `).all(year, month, today);
-  const sentSet = new Set(sentRows.map(n => `${n.bill_id}:${n.user_id}:${n.type}`));
+  const sentSet = new Set<string>(sentRows.map((n: Row) => `${n.bill_id}:${n.user_id}:${n.type}`));
 
   for (const bill of bills) {
     const dueDate = resolveDueDate(bill, year, month);
@@ -377,29 +358,21 @@ async function runNotifications() {
     if (isPaid) continue;
 
     const due     = new Date(dueDate + 'T00:00:00');
-    // Compare calendar days, not timestamps, to avoid same-day bugs
-    // (e.g., due today at midnight vs now at 3pm would give -0.625 days → floors to -1)
     const todayDate = new Date(now.getFullYear(), now.getMonth(), now.getDate());
     const dueDay    = new Date(due.getFullYear(), due.getMonth(), due.getDate());
-    const diffDays  = Math.round((dueDay - todayDate) / 86400000);
+    const diffDays  = Math.round((dueDay.getTime() - todayDate.getTime()) / 86400000);
 
-    // Determine which type applies today. The early reminder fires at the bill's
-    // own lead time (reminder_days_before, default 3) rather than a fixed 3 days.
     const type = reminderTypeFor(bill, diffDays);
-
     if (!type) continue;
 
-    // Defensive: warn if a bill somehow has no owner
     if (!bill.user_id) {
       console.warn(`[notifications] Bill id=${bill.id} name="${bill.name}" has no user_id — skipping`);
       continue;
     }
 
     for (const recipient of recipients) {
-      // In per-user mode, only send bills belonging to this recipient
       if (allowUserConfig && bill.user_id !== recipient.id) continue;
 
-      // Check recipient's preferences
       if (type === 'due_3d'    && !recipient.notify_3d)       continue;
       if (type === 'due_1d'    && !recipient.notify_1d)       continue;
       if (type === 'due_today' && !recipient.notify_due)      continue;
@@ -420,7 +393,7 @@ async function runNotifications() {
         try {
           await sendEmail(recipient.notification_email, subject, html);
           sent = true;
-        } catch (err) {
+        } catch (err: any) {
           errors.push(`email/${recipient.notification_email}/${bill.name}: ${err.message}`);
         }
       }
@@ -430,7 +403,7 @@ async function runNotifications() {
         try {
           await sendPushToUser(recipient, subject, pushBody, urgency);
           sent = true;
-        } catch (err) {
+        } catch (err: any) {
           errors.push(`push/${recipient.push_channel}/${bill.name}: ${err.message}`);
         }
       }
@@ -453,14 +426,14 @@ async function runNotifications() {
 
 // ── Drift / price-change digest email ────────────────────────────────────────
 
-function fmtAmt(n) {
+function fmtAmt(n: any): string {
   return '$' + Number(n || 0).toFixed(2);
 }
 
-function buildDriftDigestHtml(bills) {
+function buildDriftDigestHtml(bills: any[]): string {
   const color = '#d97706'; // amber-600
 
-  const rows = bills.map(b => {
+  const rows = bills.map((b: Row) => {
     const sign  = b.direction === 'up' ? '+' : '';
     const arrow = b.direction === 'up' ? '▲' : '▼';
     const arrowColor = b.direction === 'up' ? '#d97706' : '#0d9488';
@@ -526,7 +499,7 @@ async function runDriftNotifications() {
   if (!getSetting('notify_smtp_host'))               return;
   if (!getSetting('notify_sender_address'))          return;
 
-  const db = getDb();
+  const db: Db = getDb();
   const { getDriftReport } = require('./driftService.cts');
   const now   = new Date();
   const year  = now.getFullYear();
@@ -536,7 +509,7 @@ async function runDriftNotifications() {
   const allowUserConfig  = getSetting('notify_allow_user_config') === 'true';
   const globalRecipient  = getSetting('notify_global_recipient');
 
-  const recipients = [];
+  const recipients: any[] = [];
 
   if (allowUserConfig) {
     const users = db.prepare(
@@ -550,7 +523,7 @@ async function runDriftNotifications() {
   for (const recipient of recipients) {
     try {
       const report   = getDriftReport(recipient.id, now);
-      const newBills = (report.bills || []).filter(b =>
+      const newBills = (report.bills || []).filter((b: Row) =>
         !hasNotification(db, b.id, recipient.id, year, month, 'amount_change', today)
       );
       if (!newBills.length) continue;
@@ -564,18 +537,14 @@ async function runDriftNotifications() {
       for (const b of newBills) {
         recordNotification(db, b.id, recipient.id, year, month, 'amount_change', today);
       }
-    } catch (err) {
+    } catch (err: any) {
       console.error('[drift notifications] Error for recipient', recipient.notification_email, ':', err.message);
     }
   }
 }
 
 module.exports = { runNotifications, runDriftNotifications, sendTestEmail, createTransport };
-// Push helpers, exposed for the test-push route + tests. Assigned AFTER the line
-// above so it isn't clobbered by the reassignment (QA-B10-01: previously set
-// before it, leaving `_push` undefined → "Send test push" always 500'd).
+// Push helpers, exposed for the test-push route + tests (QA-B10-01: assigned AFTER the export above).
 module.exports._push = { sendNtfy, sendGotify, sendDiscord, sendTelegram, sendTestPush, sendPushToUser, encryptSecret };
 module.exports._email = { buildEmailHtml, esc };
-// Reminder lead-time logic, exposed for unit tests (the full runner uses the
-// real clock + real senders, so the pure type selection is tested in isolation).
 module.exports._reminders = { reminderTypeFor, leadDaysOf, TYPE_META };
diff --git a/services/paymentAccountingService.cts b/services/paymentAccountingService.cts
index bb522bc..f2989b7 100644
--- a/services/paymentAccountingService.cts
+++ b/services/paymentAccountingService.cts
@@ -2,7 +2,7 @@
 
 import type { Db } from '../types/db';
 
-const { computeBalanceDelta, applyBalanceDelta } = require('./billsService');
+const { computeBalanceDelta, applyBalanceDelta } = require('./billsService.cts');
 const { getCycleRange } = require('./statusService.cts');
 
 // Dynamic better-sqlite3 rows / payloads — shape varies by query, callers read
diff --git a/services/spreadsheetImportService.js b/services/spreadsheetImportService.js
index 0013e1d..6ee349d 100644
--- a/services/spreadsheetImportService.js
+++ b/services/spreadsheetImportService.js
@@ -14,7 +14,7 @@
 const xlsx    = require('xlsx');
 const crypto  = require('crypto');
 const { getDb, ensureUserDefaultCategories } = require('../db/database');
-const { computeBalanceDelta, applyBalanceDelta } = require('./billsService');
+const { computeBalanceDelta, applyBalanceDelta } = require('./billsService.cts');
 const { toCents, fromCents } = require('../utils/money.mts');
 
 // ─── Constants ────────────────────────────────────────────────────────────────
diff --git a/services/subscriptionService.js b/services/subscriptionService.js
index e8853c8..62c30e7 100644
--- a/services/subscriptionService.js
+++ b/services/subscriptionService.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const { billingCycleForCycleType, insertBill, validateBillData } = require('./billsService');
+const { billingCycleForCycleType, insertBill, validateBillData } = require('./billsService.cts');
 const { localDateString, todayLocal } = require('../utils/dates.mts');
 const { roundMoney, sumMoney, mulMoney, fromCents } = require('../utils/money.mts');
 
diff --git a/services/trackerService.js b/services/trackerService.js
index f1adabd..34036ec 100644
--- a/services/trackerService.js
+++ b/services/trackerService.js
@@ -3,7 +3,7 @@
 const { getDb } = require('../db/database');
 const { buildTrackerRow, getCycleRange, resolveDueDate, isPaidStatus } = require('./statusService.cts');
 const { getUserSettings } = require('./userSettings.cts');
-const { computeBalanceDelta, applyBalanceDelta } = require('./billsService');
+const { computeBalanceDelta, applyBalanceDelta } = require('./billsService.cts');
 const { computeAmountSuggestionsBatch } = require('./amountSuggestionService.cts');
 const { accountingActiveSql } = require('./paymentAccountingService.cts');
 const { normalizeMerchant } = require('./subscriptionService');
diff --git a/services/transactionMatchService.cts b/services/transactionMatchService.cts
index ecd0d0f..fbc2034 100644
--- a/services/transactionMatchService.cts
+++ b/services/transactionMatchService.cts
@@ -3,7 +3,7 @@
 import type { Db } from '../types/db';
 
 const { getDb } = require('../db/database');
-const { computeBalanceDelta, applyBalanceDelta } = require('./billsService');
+const { computeBalanceDelta, applyBalanceDelta } = require('./billsService.cts');
 const {
   applyBankPaymentAsSourceOfTruth,
   reactivatePaymentsOverriddenBy,
diff --git a/services/userDbImportService.js b/services/userDbImportService.js
index c98d224..fbda08b 100644
--- a/services/userDbImportService.js
+++ b/services/userDbImportService.js
@@ -6,7 +6,7 @@ const os = require('os');
 const path = require('path');
 const Database = require('better-sqlite3');
 const { getDb } = require('../db/database');
-const { billingCycleForCycleType, cycleTypeFromBillingCycle } = require('./billsService');
+const { billingCycleForCycleType, cycleTypeFromBillingCycle } = require('./billsService.cts');
 const { toCents } = require('../utils/money.mts');
 
 const MAX_SQLITE_BYTES = 50 * 1024 * 1024;
diff --git a/tests/billsService.test.js b/tests/billsService.test.js
index 16f93d5..efe4061 100644
--- a/tests/billsService.test.js
+++ b/tests/billsService.test.js
@@ -7,7 +7,7 @@ const {
   billingCycleForCycleType,
   cycleTypeFromBillingCycle,
   validateBillData,
-} = require('../services/billsService');
+} = require('../services/billsService.cts');
 
 test('billing schedule helpers map canonical cycle_type to legacy billing_cycle', () => {
   assert.equal(billingCycleForCycleType('monthly'), 'monthly');
diff --git a/tests/notificationDelivery.test.js b/tests/notificationDelivery.test.js
index bebcd2a..f3fc7ad 100644
--- a/tests/notificationDelivery.test.js
+++ b/tests/notificationDelivery.test.js
@@ -7,7 +7,7 @@ const test = require('node:test');
 const assert = require('node:assert/strict');
 const http = require('node:http');
 
-const { _push } = require('../services/notificationService');
+const { _push } = require('../services/notificationService.cts');
 const { sendNtfy, sendGotify, sendDiscord, sendPushToUser } = _push;
 
 // Local HTTP sink: records requests, status configurable.
@@ -108,7 +108,7 @@ test('dispatch: an unknown channel throws instead of silently doing nothing', as
 });
 
 test('email HTML escapes the bill name everywhere — no XSS via the name (QA-B14-04)', () => {
-  const { buildEmailHtml } = require('../services/notificationService')._email;
+  const { buildEmailHtml } = require('../services/notificationService.cts')._email;
   const evil = '<img src=x onerror=alert(1)>';
   for (const type of ['due_3d', 'due_1d', 'due_today', 'overdue']) {
     const html = buildEmailHtml({ name: evil, expected_amount: 8500 }, type, '2026-07-15');
diff --git a/tests/notificationLeadTime.test.js b/tests/notificationLeadTime.test.js
index ce62f8e..a0baba9 100644
--- a/tests/notificationLeadTime.test.js
+++ b/tests/notificationLeadTime.test.js
@@ -7,7 +7,7 @@
 const test = require('node:test');
 const assert = require('node:assert/strict');
 
-const { _reminders, _email } = require('../services/notificationService');
+const { _reminders, _email } = require('../services/notificationService.cts');
 const { reminderTypeFor, leadDaysOf, TYPE_META } = _reminders;
 
 test('leadDaysOf defaults to 3 and honors an integer reminder_days_before', () => {
diff --git a/workers/dailyWorker.js b/workers/dailyWorker.js
index af70b23..3614c50 100644
--- a/workers/dailyWorker.js
+++ b/workers/dailyWorker.js
@@ -5,7 +5,7 @@ const { getDb, getSetting } = require('../db/database');
 const { buildTrackerRow, getCycleRange } = require('../services/statusService.cts');
 const { pruneExpiredSessions } = require('../services/authService.cts');
 const { pruneExpiredChallenges: pruneWebAuthnChallenges } = require('../services/webauthnService.cts');
-const { runNotifications, runDriftNotifications } = require('../services/notificationService');
+const { runNotifications, runDriftNotifications } = require('../services/notificationService.cts');
 const { runAllCleanup } = require('../services/cleanupService.cts');
 const {
   markWorkerError,