Add recurring expenses with active nav tab highlighting

- Add RecurringExpense model to Prisma schema with migration
- Add lib/recurring-expenses.ts: CRUD + virtual projection per month
- Add /recurring-expenses API routes (GET, POST, PATCH, DELETE)
- Merge projected recurring expenses into dashboard totals and expense list
- Add RecurringExpenseManager component to /add-expense page
- Show amber "Recurring" badge on projected items; hide edit/delete for them
- Highlight active nav tab using usePathname() with hover state
- Fix Turbopack/Prisma stub issue by adding serverExternalPackages to next.config.ts
- Clear stale Turbopack stub in Dockerfile before each build

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/add-expense/page.tsx

@@ -1,4 +1,5 @@
 import { ExpenseWorkspace } from "@/components/expense-workspace";
+import { RecurringExpenseManager } from "@/components/recurring-expense-manager";
 import { CATEGORY_OPTIONS } from "@/lib/categories";
 
 export const metadata = {
@@ -16,6 +17,8 @@ export default function AddExpensePage() {
         </p>
       </header>
 
+      <RecurringExpenseManager categoryOptions={CATEGORY_OPTIONS.map((option) => ({ ...option }))} />
+
       <ExpenseWorkspace categoryOptions={CATEGORY_OPTIONS.map((option) => ({ ...option }))} />
     </div>
   );

src/app/dashboard/route.ts

@@ -21,6 +21,7 @@ export async function GET(request: Request) {
     return NextResponse.json(dashboard);
   } catch (error) {
     console.error("[dashboard] snapshot error:", error);
-    return NextResponse.json({ error: "Could not load the dashboard." }, { status: 500 });
+    const msg = error instanceof Error ? error.message : String(error);
+    return NextResponse.json({ error: "Could not load the dashboard.", detail: msg }, { status: 500 });
   }
 }

src/app/expenses/route.ts

@@ -1,11 +1,32 @@
 import { NextResponse } from "next/server";
 
+import { isDateInMonth, isValidMonthKey } from "@/lib/date";
 import { createExpense, listExpenses } from "@/lib/expenses";
+import { getProjectedRecurringExpenses, listActiveRecurringExpenses } from "@/lib/recurring-expenses";
 import { expenseInputSchema } from "@/lib/validation";
 
-export async function GET() {
-  const expenses = await listExpenses();
-  return NextResponse.json({ expenses });
+export async function GET(request: Request) {
+  const url = new URL(request.url);
+  const rawMonth = url.searchParams.get("month");
+
+  try {
+    const expenses = await listExpenses();
+
+    if (rawMonth && isValidMonthKey(rawMonth)) {
+      const definitions = await listActiveRecurringExpenses();
+      const projected = getProjectedRecurringExpenses(definitions, rawMonth);
+      const monthReal = expenses
+        .filter((e) => isDateInMonth(e.date, rawMonth))
+        .map((e) => ({ ...e, isRecurring: false as const }));
+      const all = [...monthReal, ...projected].sort((a, b) => b.date.localeCompare(a.date));
+      return NextResponse.json({ expenses: all });
+    }
+
+    return NextResponse.json({ expenses });
+  } catch (error) {
+    const msg = error instanceof Error ? error.message : String(error);
+    return NextResponse.json({ error: "Could not load expenses.", detail: msg }, { status: 500 });
+  }
 }
 
 export async function POST(request: Request) {

src/app/recurring-expenses/[id]/route.ts

@@ -0,0 +1,51 @@
+import { Prisma } from "@prisma/client";
+import { NextResponse } from "next/server";
+
+import { deactivateRecurringExpense, updateRecurringExpense } from "@/lib/recurring-expenses";
+import { recurringExpenseInputSchema } from "@/lib/validation";
+
+type RouteContext = {
+  params: Promise<{ id: string }>;
+};
+
+export async function PATCH(request: Request, context: RouteContext) {
+  const { id } = await context.params;
+  const payload = await request.json();
+  const parsed = recurringExpenseInputSchema.safeParse(payload);
+
+  if (!parsed.success) {
+    return NextResponse.json(
+      { error: parsed.error.issues[0]?.message ?? "Invalid recurring expense payload." },
+      { status: 400 },
+    );
+  }
+
+  try {
+    const recurringExpense = await updateRecurringExpense(id, {
+      title: parsed.data.title,
+      amountCents: parsed.data.amount,
+      dayOfMonth: parsed.data.dayOfMonth,
+      category: parsed.data.category,
+    });
+    return NextResponse.json({ recurringExpense });
+  } catch (error) {
+    if (error instanceof Prisma.PrismaClientKnownRequestError && error.code === "P2025") {
+      return NextResponse.json({ error: "Recurring expense not found." }, { status: 404 });
+    }
+    throw error;
+  }
+}
+
+export async function DELETE(_: Request, context: RouteContext) {
+  const { id } = await context.params;
+
+  try {
+    await deactivateRecurringExpense(id);
+    return new NextResponse(null, { status: 204 });
+  } catch (error) {
+    if (error instanceof Prisma.PrismaClientKnownRequestError && error.code === "P2025") {
+      return NextResponse.json({ error: "Recurring expense not found." }, { status: 404 });
+    }
+    throw error;
+  }
+}

src/app/recurring-expenses/route.ts

@@ -0,0 +1,30 @@
+import { NextResponse } from "next/server";
+
+import { createRecurringExpense, listActiveRecurringExpenses } from "@/lib/recurring-expenses";
+import { recurringExpenseInputSchema } from "@/lib/validation";
+
+export async function GET() {
+  const recurringExpenses = await listActiveRecurringExpenses();
+  return NextResponse.json({ recurringExpenses });
+}
+
+export async function POST(request: Request) {
+  const payload = await request.json();
+  const parsed = recurringExpenseInputSchema.safeParse(payload);
+
+  if (!parsed.success) {
+    return NextResponse.json(
+      { error: parsed.error.issues[0]?.message ?? "Invalid recurring expense payload." },
+      { status: 400 },
+    );
+  }
+
+  const recurringExpense = await createRecurringExpense({
+    title: parsed.data.title,
+    amountCents: parsed.data.amount,
+    dayOfMonth: parsed.data.dayOfMonth,
+    category: parsed.data.category,
+  });
+
+  return NextResponse.json({ recurringExpense }, { status: 201 });
+}

src/components/expense-workspace.tsx

@@ -3,6 +3,7 @@
 import { useEffect, useMemo, useState, type FormEvent } from "react";
 
 import { getCategoryLabel, type CategoryValue } from "@/lib/categories";
+import { getCurrentMonthKey } from "@/lib/date";
 import { formatCurrencyFromCents } from "@/lib/money";
 
 type SuggestionResponse = {
@@ -19,6 +20,7 @@ type ExpenseRecord = {
   amountCents: number;
   date: string;
   category: CategoryValue;
+  isRecurring?: boolean;
 };
 
 type CategoryOption = {
@@ -53,9 +55,10 @@ export function ExpenseWorkspace({ categoryOptions }: Props) {
 
   useEffect(() => {
     async function loadExpenses() {
-      const response = await fetch("/expenses", { cache: "no-store" });
-      const payload = (await response.json()) as { expenses?: ExpenseRecord[] };
-      setExpenses(payload.expenses ?? []);
+      const month = getCurrentMonthKey();
+      const response = await fetch(`/expenses?month=${month}`, { cache: "no-store" });
+      const payload = (await response.json().catch(() => null)) as { expenses?: ExpenseRecord[] } | null;
+      setExpenses(payload?.expenses ?? []);
     }
 
     void loadExpenses();
@@ -335,27 +338,38 @@ export function ExpenseWorkspace({ categoryOptions }: Props) {
                 className="flex items-center justify-between gap-4 rounded-3xl border border-stone-200 bg-white px-4 py-4"
               >
                 <div>
-                  <p className="font-semibold text-stone-950">{expense.title}</p>
+                  <div className="flex items-center gap-2">
+                    <p className="font-semibold text-stone-950">{expense.title}</p>
+                    {expense.isRecurring && (
+                      <span className="rounded-full bg-amber-100 px-2 py-0.5 text-[10px] font-semibold uppercase tracking-wider text-amber-700">
+                        Recurring
+                      </span>
+                    )}
+                  </div>
                   <p className="mt-1 text-sm text-stone-600">
                     {expense.date} · {getCategoryLabel(expense.category)}
                   </p>
                 </div>
                 <div className="flex items-center gap-2">
                   <p className="mr-2 font-semibold text-stone-950">{formatCurrencyFromCents(expense.amountCents)}</p>
-                  <button
-                    type="button"
-                    onClick={() => handleEdit(expense)}
-                    className="rounded-full border border-stone-300 px-3 py-2 text-xs font-semibold uppercase tracking-[0.2em] text-stone-600 transition hover:border-stone-900 hover:text-stone-900"
-                  >
-                    Edit
-                  </button>
-                  <button
-                    type="button"
-                    onClick={() => handleDelete(expense.id)}
-                    className="rounded-full border border-stone-300 px-3 py-2 text-xs font-semibold uppercase tracking-[0.2em] text-stone-600 transition hover:border-rose-400 hover:text-rose-600"
-                  >
-                    Delete
-                  </button>
+                  {!expense.isRecurring && (
+                    <>
+                      <button
+                        type="button"
+                        onClick={() => handleEdit(expense)}
+                        className="rounded-full border border-stone-300 px-3 py-2 text-xs font-semibold uppercase tracking-[0.2em] text-stone-600 transition hover:border-stone-900 hover:text-stone-900"
+                      >
+                        Edit
+                      </button>
+                      <button
+                        type="button"
+                        onClick={() => handleDelete(expense.id)}
+                        className="rounded-full border border-stone-300 px-3 py-2 text-xs font-semibold uppercase tracking-[0.2em] text-stone-600 transition hover:border-rose-400 hover:text-rose-600"
+                      >
+                        Delete
+                      </button>
+                    </>
+                  )}
                 </div>
               </article>
             ))

src/components/home-dashboard.tsx

@@ -26,7 +26,7 @@ type DashboardSnapshot = {
     largestExpense: { title: string; amountCents: number; date: string; category: string } | null;
   };
   categoryBreakdown: Array<{ category: string; amountCents: number }>;
-  recentExpenses: Array<{ id: string; title: string; amountCents: number; date: string; category: string }>;
+  recentExpenses: Array<{ id: string; title: string; amountCents: number; date: string; category: string; isRecurring?: true }>;
   chart: Array<{ date: string; expensesCents: number; paychecksCents: number }>;
   paySchedule: { amountCents: number; anchorDate: string; projectedDates: string[] } | null;
 };
@@ -445,7 +445,14 @@ export function HomeDashboard() {
             snapshot.recentExpenses.map((expense) => (
               <article key={expense.id} className="flex flex-wrap items-center justify-between gap-3 rounded-3xl border border-stone-200 bg-[#fffcf7] px-4 py-4">
                 <div>
-                  <p className="font-semibold text-stone-950">{expense.title}</p>
+                  <div className="flex items-center gap-2">
+                    <p className="font-semibold text-stone-950">{expense.title}</p>
+                    {expense.isRecurring && (
+                      <span className="rounded-full bg-amber-100 px-2 py-0.5 text-[10px] font-semibold uppercase tracking-wider text-amber-700">
+                        Recurring
+                      </span>
+                    )}
+                  </div>
                   <p className="mt-1 text-sm text-stone-600">
                     {expense.date} · {getCategoryLabel(expense.category as never)}
                   </p>

src/components/recurring-expense-manager.tsx

@@ -0,0 +1,277 @@
+"use client";
+
+import { useEffect, useState, type FormEvent } from "react";
+
+import { getCategoryLabel, type CategoryValue } from "@/lib/categories";
+import { formatCurrencyFromCents } from "@/lib/money";
+
+type RecurringDefinition = {
+  id: string;
+  title: string;
+  amountCents: number;
+  category: string;
+  dayOfMonth: number;
+};
+
+type CategoryOption = {
+  value: string;
+  label: string;
+};
+
+type Props = {
+  categoryOptions: CategoryOption[];
+};
+
+const emptyForm = { title: "", amount: "", dayOfMonth: "1", category: "MISC" as CategoryValue };
+
+export function RecurringExpenseManager({ categoryOptions }: Props) {
+  const [definitions, setDefinitions] = useState<RecurringDefinition[]>([]);
+  const [showAddForm, setShowAddForm] = useState(false);
+  const [editingId, setEditingId] = useState<string | null>(null);
+  const [formState, setFormState] = useState(emptyForm);
+  const [busy, setBusy] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+
+  useEffect(() => {
+    async function load() {
+      const res = await fetch("/recurring-expenses", { cache: "no-store" });
+      const payload = (await res.json()) as { recurringExpenses?: RecurringDefinition[] };
+      setDefinitions(payload.recurringExpenses ?? []);
+    }
+    void load();
+  }, []);
+
+  function openAdd() {
+    setEditingId(null);
+    setFormState(emptyForm);
+    setError(null);
+    setShowAddForm(true);
+  }
+
+  function openEdit(def: RecurringDefinition) {
+    setShowAddForm(false);
+    setEditingId(def.id);
+    setFormState({
+      title: def.title,
+      amount: (def.amountCents / 100).toFixed(2),
+      dayOfMonth: String(def.dayOfMonth),
+      category: def.category as CategoryValue,
+    });
+    setError(null);
+  }
+
+  function cancelForm() {
+    setShowAddForm(false);
+    setEditingId(null);
+    setFormState(emptyForm);
+    setError(null);
+  }
+
+  async function handleSubmit(event: FormEvent<HTMLFormElement>) {
+    event.preventDefault();
+    setBusy(true);
+    setError(null);
+
+    const isEditing = editingId !== null;
+    const url = isEditing ? `/recurring-expenses/${editingId}` : "/recurring-expenses";
+    const response = await fetch(url, {
+      method: isEditing ? "PATCH" : "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify({
+        title: formState.title,
+        amount: formState.amount,
+        dayOfMonth: parseInt(formState.dayOfMonth, 10),
+        category: formState.category,
+      }),
+    });
+
+    setBusy(false);
+
+    if (!response.ok) {
+      const payload = (await response.json().catch(() => null)) as { error?: string } | null;
+      setError(payload?.error ?? "Could not save.");
+      return;
+    }
+
+    const payload = (await response.json()) as { recurringExpense: RecurringDefinition };
+
+    if (isEditing) {
+      setDefinitions((current) =>
+        current.map((d) => (d.id === editingId ? payload.recurringExpense : d)),
+      );
+    } else {
+      setDefinitions((current) => [...current, payload.recurringExpense]);
+    }
+
+    cancelForm();
+  }
+
+  async function handleDelete(id: string) {
+    setBusy(true);
+    const response = await fetch(`/recurring-expenses/${id}`, { method: "DELETE" });
+    setBusy(false);
+
+    if (!response.ok) {
+      setError("Could not delete.");
+      return;
+    }
+
+    setDefinitions((current) => current.filter((d) => d.id !== id));
+  }
+
+  return (
+    <section className="rounded-[2rem] border border-amber-200 bg-amber-50 p-6 shadow-[0_24px_60px_rgba(120,90,50,0.08)]">
+      <div className="mb-5 flex items-center justify-between gap-4">
+        <div>
+          <p className="text-sm font-semibold uppercase tracking-[0.24em] text-amber-700">Fixed monthly costs</p>
+          <h2 className="mt-2 text-2xl font-semibold text-stone-950">Recurring expenses</h2>
+          <p className="mt-1 text-sm text-stone-600">These appear automatically in every month without manual entry.</p>
+        </div>
+        {!showAddForm && editingId === null && (
+          <button
+            type="button"
+            onClick={openAdd}
+            className="shrink-0 rounded-full bg-stone-950 px-4 py-2.5 text-sm font-semibold text-white transition hover:bg-stone-700"
+          >
+            + Add recurring
+          </button>
+        )}
+      </div>
+
+      {(showAddForm || editingId !== null) && (
+        <form
+          onSubmit={handleSubmit}
+          className="mb-5 grid gap-3 rounded-2xl border border-amber-200 bg-white p-5 md:grid-cols-2"
+        >
+          <p className="text-sm font-semibold text-stone-700 md:col-span-2">
+            {editingId ? "Edit recurring expense" : "New recurring expense"}
+          </p>
+
+          <label className="grid gap-1.5 text-sm font-medium text-stone-700 md:col-span-2">
+            Title
+            <input
+              required
+              value={formState.title}
+              onChange={(e) => setFormState((s) => ({ ...s, title: e.target.value }))}
+              className="rounded-2xl border border-stone-300 bg-stone-50 px-4 py-2.5 outline-none transition focus:border-stone-900"
+              placeholder="Rent, car insurance, EMI..."
+            />
+          </label>
+
+          <label className="grid gap-1.5 text-sm font-medium text-stone-700">
+            Amount
+            <input
+              required
+              inputMode="decimal"
+              value={formState.amount}
+              onChange={(e) => setFormState((s) => ({ ...s, amount: e.target.value }))}
+              className="rounded-2xl border border-stone-300 bg-stone-50 px-4 py-2.5 outline-none transition focus:border-stone-900"
+              placeholder="1200.00"
+            />
+          </label>
+
+          <label className="grid gap-1.5 text-sm font-medium text-stone-700">
+            Day of month
+            <input
+              required
+              type="number"
+              min={1}
+              max={28}
+              value={formState.dayOfMonth}
+              onChange={(e) => setFormState((s) => ({ ...s, dayOfMonth: e.target.value }))}
+              className="rounded-2xl border border-stone-300 bg-stone-50 px-4 py-2.5 outline-none transition focus:border-stone-900"
+              placeholder="1"
+            />
+          </label>
+
+          <label className="grid gap-1.5 text-sm font-medium text-stone-700 md:col-span-2">
+            Category
+            <select
+              value={formState.category}
+              onChange={(e) => setFormState((s) => ({ ...s, category: e.target.value as CategoryValue }))}
+              className="rounded-2xl border border-stone-300 bg-stone-50 px-4 py-2.5 outline-none transition focus:border-stone-900"
+            >
+              {categoryOptions.map((option) => (
+                <option key={option.value} value={option.value}>
+                  {option.label}
+                </option>
+              ))}
+            </select>
+          </label>
+
+          <div className="md:col-span-2 flex items-center justify-between gap-3">
+            <p className="text-sm text-rose-700">{error}</p>
+            <div className="flex gap-2">
+              <button
+                type="button"
+                onClick={cancelForm}
+                className="rounded-full border border-stone-300 px-4 py-2.5 text-sm font-semibold text-stone-700 transition hover:border-stone-900"
+              >
+                Cancel
+              </button>
+              <button
+                type="submit"
+                disabled={busy}
+                className="rounded-full bg-stone-950 px-4 py-2.5 text-sm font-semibold text-white transition hover:bg-stone-800 disabled:cursor-not-allowed disabled:bg-stone-400"
+              >
+                {busy ? "Saving..." : editingId ? "Update" : "Save"}
+              </button>
+            </div>
+          </div>
+        </form>
+      )}
+
+      {!showAddForm && editingId === null && error && (
+        <p className="mb-3 text-sm text-rose-700">{error}</p>
+      )}
+
+      {definitions.length === 0 && !showAddForm ? (
+        <div className="rounded-3xl border border-dashed border-amber-300 px-4 py-6 text-sm text-stone-600">
+          No recurring expenses yet. Add fixed monthly costs like rent or EMI.
+        </div>
+      ) : (
+        <div className="space-y-2">
+          {definitions.map((def) => (
+            <article
+              key={def.id}
+              className={`flex items-center justify-between gap-4 rounded-3xl border px-4 py-4 ${
+                editingId === def.id
+                  ? "border-amber-300 bg-amber-100/50"
+                  : "border-amber-200 bg-white"
+              }`}
+            >
+              <div>
+                <p className="font-semibold text-stone-950">{def.title}</p>
+                <p className="mt-1 text-sm text-stone-600">
+                  Day {def.dayOfMonth} each month · {getCategoryLabel(def.category as CategoryValue)}
+                </p>
+              </div>
+              <div className="flex items-center gap-2">
+                <p className="mr-2 font-semibold text-stone-950">{formatCurrencyFromCents(def.amountCents)}</p>
+                {editingId !== def.id && (
+                  <>
+                    <button
+                      type="button"
+                      onClick={() => openEdit(def)}
+                      className="rounded-full border border-stone-300 px-3 py-2 text-xs font-semibold uppercase tracking-[0.2em] text-stone-600 transition hover:border-stone-900 hover:text-stone-900"
+                    >
+                      Edit
+                    </button>
+                    <button
+                      type="button"
+                      disabled={busy}
+                      onClick={() => void handleDelete(def.id)}
+                      className="rounded-full border border-stone-300 px-3 py-2 text-xs font-semibold uppercase tracking-[0.2em] text-stone-600 transition hover:border-rose-400 hover:text-rose-600 disabled:cursor-not-allowed"
+                    >
+                      Delete
+                    </button>
+                  </>
+                )}
+              </div>
+            </article>
+          ))}
+        </div>
+      )}
+    </section>
+  );
+}

src/components/site-nav.tsx

@@ -1,4 +1,7 @@
+"use client";
+
 import Link from "next/link";
+import { usePathname } from "next/navigation";
 
 const links = [
   { href: "/", label: "Dashboard" },
@@ -7,17 +10,26 @@ const links = [
 ];
 
 export function SiteNav() {
+  const pathname = usePathname();
+
   return (
     <nav className="flex flex-wrap gap-3 text-sm font-semibold text-stone-700">
-      {links.map((link) => (
-        <Link
-          key={link.href}
-          href={link.href}
-          className="rounded-full border border-stone-300/80 bg-white/80 px-4 py-2 transition hover:border-stone-900 hover:text-stone-950"
-        >
-          {link.label}
-        </Link>
-      ))}
+      {links.map((link) => {
+        const isActive = link.href === "/" ? pathname === "/" : pathname.startsWith(link.href);
+        return (
+          <Link
+            key={link.href}
+            href={link.href}
+            className={
+              isActive
+                ? "rounded-full border border-stone-900 bg-stone-900 px-4 py-2 text-white transition hover:bg-stone-700 hover:border-stone-700"
+                : "rounded-full border border-stone-300/80 bg-white/80 px-4 py-2 transition hover:border-stone-900 hover:text-stone-950"
+            }
+          >
+            {link.label}
+          </Link>
+        );
+      })}
     </nav>
   );
 }

src/lib/dashboard.ts

@@ -10,6 +10,11 @@ import {
   isDateInMonth,
 } from "@/lib/date";
 import { getActiveSchedule, getProjectedPayDates, type PaySchedule } from "@/lib/pay-schedule";
+import {
+  getProjectedRecurringExpenses,
+  listActiveRecurringExpenses,
+  type ProjectedRecurringExpense,
+} from "@/lib/recurring-expenses";
 
 export type DashboardSnapshot = {
   month: string;
@@ -30,7 +35,7 @@ export type DashboardSnapshot = {
     largestExpense: { title: string; amountCents: number; date: string; category: string } | null;
   };
   categoryBreakdown: Array<{ category: string; amountCents: number }>;
-  recentExpenses: Array<{ id: string; title: string; amountCents: number; date: string; category: string }>;
+  recentExpenses: Array<{ id: string; title: string; amountCents: number; date: string; category: string; isRecurring?: true }>;
   chart: Array<{ date: string; expensesCents: number; paychecksCents: number }>;
   paySchedule: {
     amountCents: number;
@@ -45,8 +50,10 @@ export function buildDashboardSnapshot(input: {
   paychecks: Paycheck[];
   paySchedule?: PaySchedule | null;
   insight?: MonthlyInsight | null;
+  projectedRecurring?: ProjectedRecurringExpense[];
 }): DashboardSnapshot {
   const monthExpenses = input.expenses.filter((expense) => isDateInMonth(expense.date, input.month));
+  const recurringExpenses = input.projectedRecurring ?? [];
   const monthPaychecks = input.paychecks.filter((paycheck) => isDateInMonth(paycheck.payDate, input.month));
 
   // Project biweekly pay dates; suppress any that already have a manual paycheck on the same date
@@ -63,7 +70,12 @@ export function buildDashboardSnapshot(input: {
     ...projectedPaychecks,
   ];
 
-  const expensesCents = monthExpenses.reduce((sum, expense) => sum + expense.amountCents, 0);
+  const allMonthExpenses = [
+    ...monthExpenses.map((e) => ({ ...e, isRecurring: undefined as true | undefined })),
+    ...recurringExpenses,
+  ];
+
+  const expensesCents = allMonthExpenses.reduce((sum, expense) => sum + expense.amountCents, 0);
   const paychecksCents = allPaychecks.reduce((sum, p) => sum + p.amountCents, 0);
   const netCashFlowCents = paychecksCents - expensesCents;
 
@@ -72,7 +84,7 @@ export function buildDashboardSnapshot(input: {
     : getDaysInMonth(input.month);
 
   const categoryTotals = new Map<string, number>();
-  for (const expense of monthExpenses) {
+  for (const expense of allMonthExpenses) {
     categoryTotals.set(expense.category, (categoryTotals.get(expense.category) ?? 0) + expense.amountCents);
   }
 
@@ -83,13 +95,13 @@ export function buildDashboardSnapshot(input: {
   const highestCategory = categoryBreakdown[0] ?? null;
 
   const largestExpense =
-    monthExpenses
+    allMonthExpenses
       .slice()
       .sort((left, right) => right.amountCents - left.amountCents || right.date.localeCompare(left.date))[0] ?? null;
 
   const dailyMap = new Map<string, { expensesCents: number; paychecksCents: number }>();
 
-  for (const expense of monthExpenses) {
+  for (const expense of allMonthExpenses) {
     const current = dailyMap.get(expense.date) ?? { expensesCents: 0, paychecksCents: 0 };
     current.expensesCents += expense.amountCents;
     dailyMap.set(expense.date, current);
@@ -136,9 +148,16 @@ export function buildDashboardSnapshot(input: {
       ? { amountCents: input.paySchedule.amountCents, anchorDate: input.paySchedule.anchorDate, projectedDates }
       : null,
     categoryBreakdown,
-    recentExpenses: monthExpenses
+    recentExpenses: allMonthExpenses
       .slice()
-      .sort((left, right) => right.date.localeCompare(left.date) || right.createdAt.getTime() - left.createdAt.getTime())
+      .sort((left, right) => {
+        const dateDiff = right.date.localeCompare(left.date);
+        if (dateDiff !== 0) return dateDiff;
+        // Real expenses have createdAt; projected recurring don't — sort them after real ones
+        const leftTime = "createdAt" in left ? (left.createdAt as Date).getTime() : 0;
+        const rightTime = "createdAt" in right ? (right.createdAt as Date).getTime() : 0;
+        return rightTime - leftTime;
+      })
       .slice(0, 6)
       .map((expense) => ({
         id: expense.id,
@@ -146,18 +165,22 @@ export function buildDashboardSnapshot(input: {
         amountCents: expense.amountCents,
         date: expense.date,
         category: expense.category,
+        ...(expense.isRecurring ? { isRecurring: true as const } : {}),
       })),
     chart,
   };
 }
 
 export async function getDashboardSnapshot(month = getCurrentMonthKey()) {
-  const [expenses, paychecks, insight, paySchedule] = await Promise.all([
+  const [expenses, paychecks, insight, paySchedule, recurringDefinitions] = await Promise.all([
     db.expense.findMany({ orderBy: [{ date: "desc" }, { createdAt: "desc" }] }),
     db.paycheck.findMany({ orderBy: [{ payDate: "desc" }, { createdAt: "desc" }] }),
     db.monthlyInsight.findUnique({ where: { month } }),
     getActiveSchedule(),
+    listActiveRecurringExpenses(),
   ]);
 
-  return buildDashboardSnapshot({ month, expenses, paychecks, paySchedule, insight });
+  const projectedRecurring = getProjectedRecurringExpenses(recurringDefinitions, month);
+
+  return buildDashboardSnapshot({ month, expenses, paychecks, paySchedule, insight, projectedRecurring });
 }

src/lib/recurring-expenses.ts

@@ -0,0 +1,87 @@
+import type { Category } from "@prisma/client";
+
+import { db } from "@/lib/db";
+
+export type RecurringExpense = {
+  id: string;
+  title: string;
+  amountCents: number;
+  category: string;
+  dayOfMonth: number;
+  active: boolean;
+};
+
+export type ProjectedRecurringExpense = {
+  id: string;
+  recurringId: string;
+  title: string;
+  amountCents: number;
+  category: string;
+  date: string;
+  isRecurring: true;
+};
+
+export async function listActiveRecurringExpenses(): Promise<RecurringExpense[]> {
+  return db.recurringExpense.findMany({
+    where: { active: true },
+    orderBy: { createdAt: "asc" },
+  });
+}
+
+export async function createRecurringExpense(input: {
+  title: string;
+  amountCents: number;
+  category: Category;
+  dayOfMonth: number;
+}): Promise<RecurringExpense> {
+  return db.recurringExpense.create({
+    data: {
+      title: input.title.trim(),
+      amountCents: input.amountCents,
+      category: input.category,
+      dayOfMonth: input.dayOfMonth,
+    },
+  });
+}
+
+export async function updateRecurringExpense(
+  id: string,
+  input: { title: string; amountCents: number; category: Category; dayOfMonth: number },
+): Promise<RecurringExpense> {
+  return db.recurringExpense.update({
+    where: { id },
+    data: {
+      title: input.title.trim(),
+      amountCents: input.amountCents,
+      category: input.category,
+      dayOfMonth: input.dayOfMonth,
+    },
+  });
+}
+
+export async function deactivateRecurringExpense(id: string): Promise<void> {
+  await db.recurringExpense.update({ where: { id }, data: { active: false } });
+}
+
+/**
+ * Pure function — no DB access. Projects recurring expense definitions into
+ * virtual expense objects for the given month (YYYY-MM).
+ */
+export function getProjectedRecurringExpenses(
+  definitions: RecurringExpense[],
+  month: string,
+): ProjectedRecurringExpense[] {
+  return definitions.map((def) => {
+    const day = String(def.dayOfMonth).padStart(2, "0");
+    const date = `${month}-${day}`;
+    return {
+      id: `recurring-${def.id}-${month}`,
+      recurringId: def.id,
+      title: def.title,
+      amountCents: def.amountCents,
+      category: def.category,
+      date,
+      isRecurring: true as const,
+    };
+  });
+}

src/lib/validation.ts

@@ -35,5 +35,17 @@ export const monthQuerySchema = z.object({
   month: z.string().refine(isValidMonthKey, "Use a YYYY-MM month."),
 });
 
+export const recurringExpenseInputSchema = z.object({
+  title: z.string().trim().min(1, "Title is required.").max(80, "Keep titles under 80 characters."),
+  amount: amountSchema,
+  dayOfMonth: z
+    .number({ invalid_type_error: "Day must be a number." })
+    .int()
+    .min(1, "Day must be at least 1.")
+    .max(28, "Day must be 28 or less (works across all months)."),
+  category: z.nativeEnum(Category, { message: "Choose a valid category." }),
+});
+
 export type ExpenseInput = z.infer<typeof expenseInputSchema>;
 export type PaycheckInput = z.infer<typeof paycheckInputSchema>;
+export type RecurringExpenseInput = z.infer<typeof recurringExpenseInputSchema>;