Add biweekly pay schedule with projected paychecks and dashboard integration

- Add PaySchedule model (anchorDate + amountCents + active flag)
- Add /pay-schedule API route (GET, POST, DELETE)
- Project biweekly pay dates from anchor; deduplicate against manual paychecks
- Merge projected paychecks into dashboard totals and daily chart
- Fix DST day-shift bug in getProjectedPayDates by using Date.UTC throughout
- Rewrite paycheck workspace: schedule panel at top, manual entry below,
  projected dates with "Mark received" buttons, confirmed badges
- Pass paySchedule context to Ollama insight prompt

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

prisma/migrations/20260323203003_add_pay_schedule/migration.sql

@@ -0,0 +1,8 @@
+-- CreateTable
+CREATE TABLE "PaySchedule" (
+    "id" TEXT NOT NULL PRIMARY KEY,
+    "amountCents" INTEGER NOT NULL,
+    "anchorDate" TEXT NOT NULL,
+    "active" BOOLEAN NOT NULL DEFAULT true,
+    "createdAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
+);

prisma/schema.prisma

@@ -34,6 +34,14 @@ model Paycheck {
   createdAt   DateTime @default(now())
 }
 
+model PaySchedule {
+  id          String   @id @default(cuid())
+  amountCents Int
+  anchorDate  String
+  active      Boolean  @default(true)
+  createdAt   DateTime @default(now())
+}
+
 model MonthlyInsight {
   id              String   @id @default(cuid())
   month           String   @unique

src/app/pay-schedule/route.ts

@@ -0,0 +1,45 @@
+import { NextResponse } from "next/server";
+import { z } from "zod";
+
+import { isValidLocalDate } from "@/lib/date";
+import { getActiveSchedule, saveSchedule, clearSchedule } from "@/lib/pay-schedule";
+import { parseAmountToCents } from "@/lib/money";
+
+const scheduleInputSchema = z.object({
+  amount: z
+    .union([z.string(), z.number()])
+    .transform((value, ctx) => {
+      const cents = parseAmountToCents(value);
+      if (!cents) {
+        ctx.addIssue({ code: z.ZodIssueCode.custom, message: "Enter a valid amount." });
+        return z.NEVER;
+      }
+      return cents;
+    }),
+  anchorDate: z.string().refine(isValidLocalDate, "Enter a valid date."),
+});
+
+export async function GET() {
+  const schedule = await getActiveSchedule();
+  return NextResponse.json({ schedule });
+}
+
+export async function POST(request: Request) {
+  const payload = await request.json();
+  const parsed = scheduleInputSchema.safeParse(payload);
+
+  if (!parsed.success) {
+    return NextResponse.json(
+      { error: parsed.error.issues[0]?.message ?? "Invalid schedule payload." },
+      { status: 400 },
+    );
+  }
+
+  const schedule = await saveSchedule(parsed.data.amount, parsed.data.anchorDate);
+  return NextResponse.json({ schedule }, { status: 201 });
+}
+
+export async function DELETE() {
+  await clearSchedule();
+  return new NextResponse(null, { status: 204 });
+}

src/components/paycheck-workspace.tsx

@@ -2,6 +2,7 @@
 
 import { useEffect, useMemo, useState, type FormEvent } from "react";
 
+import { getCurrentMonthKey } from "@/lib/date";
 import { formatCurrencyFromCents } from "@/lib/money";
 
 type PaycheckRecord = {
@@ -10,8 +11,18 @@ type PaycheckRecord = {
   payDate: string;
 };
 
+type PaySchedule = {
+  id: string;
+  amountCents: number;
+  anchorDate: string;
+};
+
 export function PaycheckWorkspace() {
   const [paychecks, setPaychecks] = useState<PaycheckRecord[]>([]);
+  const [schedule, setSchedule] = useState<PaySchedule | null>(null);
+  const [projectedDates, setProjectedDates] = useState<string[]>([]);
+  const [scheduleForm, setScheduleForm] = useState({ amount: "", anchorDate: new Date().toISOString().slice(0, 10) });
+  const [showScheduleForm, setShowScheduleForm] = useState(false);
   const [formState, setFormState] = useState({
     amount: "",
     payDate: new Date().toISOString().slice(0, 10),
@@ -20,13 +31,22 @@ export function PaycheckWorkspace() {
   const [error, setError] = useState<string | null>(null);
 
   useEffect(() => {
-    async function loadPaychecks() {
-      const response = await fetch("/paychecks", { cache: "no-store" });
-      const payload = (await response.json()) as { paychecks?: PaycheckRecord[] };
-      setPaychecks(payload.paychecks ?? []);
+    async function loadData() {
+      const [paycheckRes, scheduleRes] = await Promise.all([
+        fetch("/paychecks", { cache: "no-store" }),
+        fetch("/pay-schedule", { cache: "no-store" }),
+      ]);
+      const paycheckPayload = (await paycheckRes.json()) as { paychecks?: PaycheckRecord[] };
+      setPaychecks(paycheckPayload.paychecks ?? []);
+
+      const schedulePayload = (await scheduleRes.json().catch(() => ({ schedule: null }))) as { schedule?: PaySchedule | null };
+      if (schedulePayload.schedule) {
+        setSchedule(schedulePayload.schedule);
+        setProjectedDates(computeProjectedDates(schedulePayload.schedule.anchorDate, getCurrentMonthKey()));
+      }
     }
 
-    void loadPaychecks();
+    void loadData();
   }, []);
 
   const totalIncome = useMemo(
@@ -34,6 +54,71 @@ export function PaycheckWorkspace() {
     [paychecks],
   );
 
+  // Projected dates that don't already have a manual paycheck
+  const manualPayDates = useMemo(() => new Set(paychecks.map((p) => p.payDate)), [paychecks]);
+  const pendingProjectedDates = useMemo(
+    () => projectedDates.filter((d) => !manualPayDates.has(d)),
+    [projectedDates, manualPayDates],
+  );
+
+  async function handleSaveSchedule(event: FormEvent<HTMLFormElement>) {
+    event.preventDefault();
+    setBusy(true);
+    setError(null);
+
+    const response = await fetch("/pay-schedule", {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify(scheduleForm),
+    });
+
+    setBusy(false);
+
+    if (!response.ok) {
+      const payload = (await response.json().catch(() => null)) as { error?: string } | null;
+      setError(payload?.error ?? "Could not save the schedule.");
+      return;
+    }
+
+    const payload = (await response.json()) as { schedule: PaySchedule };
+    setSchedule(payload.schedule);
+    setProjectedDates(computeProjectedDates(payload.schedule.anchorDate, getCurrentMonthKey()));
+    setShowScheduleForm(false);
+    setScheduleForm({ amount: "", anchorDate: new Date().toISOString().slice(0, 10) });
+  }
+
+  async function handleClearSchedule() {
+    setBusy(true);
+    await fetch("/pay-schedule", { method: "DELETE" });
+    setBusy(false);
+    setSchedule(null);
+    setProjectedDates([]);
+  }
+
+  async function handleConfirmProjected(date: string) {
+    if (!schedule) return;
+    setBusy(true);
+    setError(null);
+
+    const amount = (schedule.amountCents / 100).toFixed(2);
+    const response = await fetch("/paychecks", {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify({ amount, payDate: date }),
+    });
+
+    setBusy(false);
+
+    if (!response.ok) {
+      const payload = (await response.json().catch(() => null)) as { error?: string } | null;
+      setError(payload?.error ?? "Could not confirm paycheck.");
+      return;
+    }
+
+    const payload = (await response.json()) as { paycheck: PaycheckRecord };
+    setPaychecks((current) => [payload.paycheck, ...current]);
+  }
+
   async function handleSubmit(event: FormEvent<HTMLFormElement>) {
     event.preventDefault();
     setBusy(true);
@@ -75,92 +160,272 @@ export function PaycheckWorkspace() {
   }
 
   return (
-    <div className="grid gap-6 lg:grid-cols-[1.1fr_0.9fr]">
-      <section className="rounded-[2rem] border border-stone-200 bg-white p-6 shadow-[0_24px_60px_rgba(120,90,50,0.08)]">
-        <div className="mb-6 flex items-center justify-between gap-4">
+    <div className="space-y-6">
+      {/* Biweekly schedule panel */}
+      <section className="rounded-[2rem] border border-emerald-100 bg-gradient-to-br from-[#f6fbf6] to-[#edf7ed] p-6 shadow-[0_24px_60px_rgba(60,120,60,0.06)]">
+        <div className="flex flex-wrap items-center justify-between gap-4">
           <div>
-            <p className="text-sm font-semibold uppercase tracking-[0.24em] text-emerald-700">Income entry</p>
-            <h2 className="mt-2 text-3xl font-semibold text-stone-950">Record each paycheck on the date it lands</h2>
+            <p className="text-sm font-semibold uppercase tracking-[0.24em] text-emerald-700">Biweekly schedule</p>
+            <h2 className="mt-1 text-2xl font-semibold text-stone-950">
+              {schedule ? "Active pay schedule" : "Set up your pay schedule"}
+            </h2>
           </div>
-          <div className="rounded-2xl bg-emerald-50 px-4 py-3 text-right">
-            <p className="text-xs uppercase tracking-[0.2em] text-emerald-700">Tracked paychecks</p>
-            <p className="mt-1 text-2xl font-semibold text-stone-950">{formatCurrencyFromCents(totalIncome)}</p>
-          </div>
-        </div>
-
-        <form className="grid gap-4 md:grid-cols-2" onSubmit={handleSubmit}>
-          <label className="grid gap-2 text-sm font-medium text-stone-700">
-            Amount
-            <input
-              required
-              inputMode="decimal"
-              value={formState.amount}
-              onChange={(event) => setFormState((current) => ({ ...current, amount: event.target.value }))}
-              className="rounded-2xl border border-stone-300 bg-stone-50 px-4 py-3 outline-none transition focus:border-stone-900"
-              placeholder="1800.00"
-            />
-          </label>
-
-          <label className="grid gap-2 text-sm font-medium text-stone-700">
-            Pay date
-            <input
-              required
-              type="date"
-              value={formState.payDate}
-              onChange={(event) => setFormState((current) => ({ ...current, payDate: event.target.value }))}
-              className="rounded-2xl border border-stone-300 bg-stone-50 px-4 py-3 outline-none transition focus:border-stone-900"
-            />
-          </label>
-
-          <div className="md:col-span-2 flex items-center justify-between gap-3">
-            <p className="text-sm text-rose-700">{error}</p>
-            <button
-              type="submit"
-              disabled={busy}
-              className="rounded-full bg-stone-950 px-5 py-3 text-sm font-semibold text-white transition hover:bg-stone-800 disabled:cursor-not-allowed disabled:bg-stone-400"
-            >
-              {busy ? "Saving..." : "Save paycheck"}
-            </button>
-          </div>
-        </form>
-      </section>
-
-      <section className="rounded-[2rem] border border-stone-200 bg-[#f6fbf6] p-6 shadow-[0_24px_60px_rgba(120,90,50,0.08)]">
-        <div className="mb-5">
-          <p className="text-sm font-semibold uppercase tracking-[0.24em] text-stone-500">Income history</p>
-          <h2 className="mt-2 text-2xl font-semibold text-stone-950">Recent paychecks</h2>
-        </div>
-
-        <div className="space-y-3">
-          {paychecks.length === 0 ? (
-            <div className="rounded-3xl border border-dashed border-stone-300 px-4 py-6 text-sm text-stone-600">
-              No paychecks yet. Add the next deposit to start cash-flow tracking.
+          {schedule ? (
+            <div className="flex gap-2">
+              <button
+                type="button"
+                onClick={() => { setShowScheduleForm(true); setScheduleForm({ amount: (schedule.amountCents / 100).toFixed(2), anchorDate: schedule.anchorDate }); }}
+                className="rounded-full border border-stone-300 px-4 py-2 text-xs font-semibold uppercase tracking-[0.2em] text-stone-700 transition hover:border-stone-900"
+              >
+                Edit
+              </button>
+              <button
+                type="button"
+                onClick={() => void handleClearSchedule()}
+                disabled={busy}
+                className="rounded-full border border-stone-300 px-4 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"
+              >
+                Clear
+              </button>
             </div>
           ) : (
-            paychecks.map((paycheck) => (
-              <article
-                key={paycheck.id}
-                className="flex items-center justify-between gap-4 rounded-3xl border border-stone-200 bg-white px-4 py-4"
+            !showScheduleForm && (
+              <button
+                type="button"
+                onClick={() => setShowScheduleForm(true)}
+                className="rounded-full bg-emerald-700 px-5 py-2.5 text-sm font-semibold text-white transition hover:bg-emerald-800"
               >
-                <div>
-                  <p className="font-semibold text-stone-950">Paycheck</p>
-                  <p className="mt-1 text-sm text-stone-600">{paycheck.payDate}</p>
-                </div>
-                <div className="flex items-center gap-4">
-                  <p className="font-semibold text-stone-950">{formatCurrencyFromCents(paycheck.amountCents)}</p>
-                  <button
-                    type="button"
-                    onClick={() => handleDelete(paycheck.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>
-            ))
+                Set up schedule
+              </button>
+            )
           )}
         </div>
+
+        {showScheduleForm && (
+          <form className="mt-5 grid gap-4 sm:grid-cols-[1fr_1fr_auto]" onSubmit={handleSaveSchedule}>
+            <label className="grid gap-2 text-sm font-medium text-stone-700">
+              Amount per paycheck
+              <input
+                required
+                inputMode="decimal"
+                value={scheduleForm.amount}
+                onChange={(e) => setScheduleForm((s) => ({ ...s, amount: e.target.value }))}
+                className="rounded-2xl border border-stone-300 bg-white px-4 py-3 outline-none transition focus:border-emerald-600"
+                placeholder="2400.00"
+              />
+            </label>
+            <label className="grid gap-2 text-sm font-medium text-stone-700">
+              A known pay date (anchor)
+              <input
+                required
+                type="date"
+                value={scheduleForm.anchorDate}
+                onChange={(e) => setScheduleForm((s) => ({ ...s, anchorDate: e.target.value }))}
+                className="rounded-2xl border border-stone-300 bg-white px-4 py-3 outline-none transition focus:border-emerald-600"
+              />
+            </label>
+            <div className="flex items-end gap-2">
+              <button
+                type="submit"
+                disabled={busy}
+                className="rounded-full bg-stone-950 px-5 py-3 text-sm font-semibold text-white transition hover:bg-stone-800 disabled:cursor-not-allowed disabled:bg-stone-400"
+              >
+                {busy ? "Saving..." : "Save"}
+              </button>
+              <button
+                type="button"
+                onClick={() => setShowScheduleForm(false)}
+                className="rounded-full border border-stone-300 px-5 py-3 text-sm font-semibold text-stone-700 transition hover:border-stone-900"
+              >
+                Cancel
+              </button>
+            </div>
+          </form>
+        )}
+
+        {schedule && !showScheduleForm && (
+          <div className="mt-5">
+            <div className="flex flex-wrap gap-6 text-sm text-stone-600">
+              <span>
+                Amount: <span className="font-semibold text-stone-950">{formatCurrencyFromCents(schedule.amountCents)}</span>
+              </span>
+              <span>
+                Cadence: <span className="font-semibold text-stone-950">Every 2 weeks</span>
+              </span>
+              <span>
+                Anchor: <span className="font-semibold text-stone-950">{schedule.anchorDate}</span>
+              </span>
+            </div>
+
+            {projectedDates.length > 0 && (
+              <div className="mt-4">
+                <p className="text-xs font-semibold uppercase tracking-[0.2em] text-stone-500">
+                  Projected pay dates this month
+                </p>
+                <div className="mt-2 flex flex-wrap gap-3">
+                  {projectedDates.map((date) => {
+                    const confirmed = manualPayDates.has(date);
+                    return (
+                      <div
+                        key={date}
+                        className={`flex items-center gap-2 rounded-2xl border px-4 py-2 text-sm ${
+                          confirmed
+                            ? "border-emerald-200 bg-emerald-50 text-emerald-800"
+                            : "border-stone-200 bg-white text-stone-700"
+                        }`}
+                      >
+                        <span className="font-medium">{date}</span>
+                        {confirmed ? (
+                          <span className="text-xs font-semibold text-emerald-600">✓ Confirmed</span>
+                        ) : (
+                          <button
+                            type="button"
+                            onClick={() => void handleConfirmProjected(date)}
+                            disabled={busy}
+                            className="rounded-full bg-emerald-700 px-2.5 py-1 text-xs font-semibold text-white transition hover:bg-emerald-800 disabled:cursor-not-allowed disabled:bg-stone-400"
+                          >
+                            Mark received
+                          </button>
+                        )}
+                      </div>
+                    );
+                  })}
+                </div>
+                {pendingProjectedDates.length > 0 && (
+                  <p className="mt-2 text-xs text-stone-500">
+                    {pendingProjectedDates.length} pending — included in dashboard totals as projected income.
+                  </p>
+                )}
+              </div>
+            )}
+          </div>
+        )}
       </section>
+
+      <div className="grid gap-6 lg:grid-cols-[1.1fr_0.9fr]">
+        {/* Manual paycheck entry */}
+        <section className="rounded-[2rem] border border-stone-200 bg-white p-6 shadow-[0_24px_60px_rgba(120,90,50,0.08)]">
+          <div className="mb-6 flex items-center justify-between gap-4">
+            <div>
+              <p className="text-sm font-semibold uppercase tracking-[0.24em] text-emerald-700">One-off entry</p>
+              <h2 className="mt-2 text-3xl font-semibold text-stone-950">Log a bonus or extra deposit</h2>
+            </div>
+            <div className="rounded-2xl bg-emerald-50 px-4 py-3 text-right">
+              <p className="text-xs uppercase tracking-[0.2em] text-emerald-700">Tracked paychecks</p>
+              <p className="mt-1 text-2xl font-semibold text-stone-950">{formatCurrencyFromCents(totalIncome)}</p>
+            </div>
+          </div>
+
+          <form className="grid gap-4 md:grid-cols-2" onSubmit={handleSubmit}>
+            <label className="grid gap-2 text-sm font-medium text-stone-700">
+              Amount
+              <input
+                required
+                inputMode="decimal"
+                value={formState.amount}
+                onChange={(event) => setFormState((current) => ({ ...current, amount: event.target.value }))}
+                className="rounded-2xl border border-stone-300 bg-stone-50 px-4 py-3 outline-none transition focus:border-stone-900"
+                placeholder="1800.00"
+              />
+            </label>
+
+            <label className="grid gap-2 text-sm font-medium text-stone-700">
+              Pay date
+              <input
+                required
+                type="date"
+                value={formState.payDate}
+                onChange={(event) => setFormState((current) => ({ ...current, payDate: event.target.value }))}
+                className="rounded-2xl border border-stone-300 bg-stone-50 px-4 py-3 outline-none transition focus:border-stone-900"
+              />
+            </label>
+
+            <div className="md:col-span-2 flex items-center justify-between gap-3">
+              <p className="text-sm text-rose-700">{error}</p>
+              <button
+                type="submit"
+                disabled={busy}
+                className="rounded-full bg-stone-950 px-5 py-3 text-sm font-semibold text-white transition hover:bg-stone-800 disabled:cursor-not-allowed disabled:bg-stone-400"
+              >
+                {busy ? "Saving..." : "Save paycheck"}
+              </button>
+            </div>
+          </form>
+        </section>
+
+        {/* Paycheck history */}
+        <section className="rounded-[2rem] border border-stone-200 bg-[#f6fbf6] p-6 shadow-[0_24px_60px_rgba(120,90,50,0.08)]">
+          <div className="mb-5">
+            <p className="text-sm font-semibold uppercase tracking-[0.24em] text-stone-500">Income history</p>
+            <h2 className="mt-2 text-2xl font-semibold text-stone-950">Recent paychecks</h2>
+          </div>
+
+          <div className="space-y-3">
+            {paychecks.length === 0 ? (
+              <div className="rounded-3xl border border-dashed border-stone-300 px-4 py-6 text-sm text-stone-600">
+                No paychecks yet. Use &quot;Mark received&quot; on a projected date or add one manually.
+              </div>
+            ) : (
+              paychecks.map((paycheck) => (
+                <article
+                  key={paycheck.id}
+                  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">Paycheck</p>
+                    <p className="mt-1 text-sm text-stone-600">{paycheck.payDate}</p>
+                  </div>
+                  <div className="flex items-center gap-4">
+                    <p className="font-semibold text-stone-950">{formatCurrencyFromCents(paycheck.amountCents)}</p>
+                    <button
+                      type="button"
+                      onClick={() => void handleDelete(paycheck.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>
+              ))
+            )}
+          </div>
+        </section>
+      </div>
     </div>
   );
 }
+
+/**
+ * Client-side projection — mirrors the server-side logic in src/lib/pay-schedule.ts
+ * so the UI can show projected dates without a round-trip.
+ */
+function computeProjectedDates(anchorDate: string, month: string): string[] {
+  const [aY, aM, aD] = anchorDate.split("-").map(Number);
+  const [year, mon] = month.split("-").map(Number);
+
+  const anchor = new Date(aY, aM - 1, aD);
+  const monthStart = new Date(year, mon - 1, 1);
+  const monthEnd = new Date(year, mon, 0);
+
+  const MS_PER_DAY = 86_400_000;
+  const period = 14 * MS_PER_DAY;
+  const anchorMs = anchor.getTime();
+  const monthStartMs = monthStart.getTime();
+  const monthEndMs = monthEnd.getTime();
+
+  const diff = monthStartMs - anchorMs;
+  const periods = Math.floor(diff / period);
+  let current = anchorMs + periods * period;
+  while (current < monthStartMs) current += period;
+
+  const results: string[] = [];
+  while (current <= monthEndMs) {
+    const d = new Date(current);
+    const y = d.getFullYear();
+    const m = String(d.getMonth() + 1).padStart(2, "0");
+    const day = String(d.getDate()).padStart(2, "0");
+    results.push(`${y}-${m}-${day}`);
+    current += period;
+  }
+  return results;
+}

src/lib/dashboard.ts

@@ -9,6 +9,7 @@ import {
   isCurrentMonthKey,
   isDateInMonth,
 } from "@/lib/date";
+import { getActiveSchedule, getProjectedPayDates, type PaySchedule } from "@/lib/pay-schedule";
 
 export type DashboardSnapshot = {
   month: string;
@@ -31,19 +32,39 @@ export type DashboardSnapshot = {
   categoryBreakdown: Array<{ category: string; amountCents: number }>;
   recentExpenses: Array<{ id: string; title: string; amountCents: number; date: string; category: string }>;
   chart: Array<{ date: string; expensesCents: number; paychecksCents: number }>;
+  paySchedule: {
+    amountCents: number;
+    anchorDate: string;
+    projectedDates: string[];
+  } | null;
 };
 
 export function buildDashboardSnapshot(input: {
   month: string;
   expenses: Expense[];
   paychecks: Paycheck[];
+  paySchedule?: PaySchedule | null;
   insight?: MonthlyInsight | null;
 }): DashboardSnapshot {
   const monthExpenses = input.expenses.filter((expense) => isDateInMonth(expense.date, input.month));
   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
+  const manualPayDates = new Set(monthPaychecks.map((p) => p.payDate));
+  const projectedDates = input.paySchedule
+    ? getProjectedPayDates(input.paySchedule.anchorDate, input.month)
+    : [];
+  const projectedPaychecks = projectedDates
+    .filter((date) => !manualPayDates.has(date))
+    .map((date) => ({ payDate: date, amountCents: input.paySchedule!.amountCents }));
+
+  const allPaychecks = [
+    ...monthPaychecks.map((p) => ({ payDate: p.payDate, amountCents: p.amountCents })),
+    ...projectedPaychecks,
+  ];
+
   const expensesCents = monthExpenses.reduce((sum, expense) => sum + expense.amountCents, 0);
-  const paychecksCents = monthPaychecks.reduce((sum, paycheck) => sum + paycheck.amountCents, 0);
+  const paychecksCents = allPaychecks.reduce((sum, p) => sum + p.amountCents, 0);
   const netCashFlowCents = paychecksCents - expensesCents;
 
   const daysConsidered = isCurrentMonthKey(input.month)
@@ -74,7 +95,7 @@ export function buildDashboardSnapshot(input: {
     dailyMap.set(expense.date, current);
   }
 
-  for (const paycheck of monthPaychecks) {
+  for (const paycheck of allPaychecks) {
     const current = dailyMap.get(paycheck.payDate) ?? { expensesCents: 0, paychecksCents: 0 };
     current.paychecksCents += paycheck.amountCents;
     dailyMap.set(paycheck.payDate, current);
@@ -111,6 +132,9 @@ export function buildDashboardSnapshot(input: {
           }
         : null,
     },
+    paySchedule: input.paySchedule
+      ? { amountCents: input.paySchedule.amountCents, anchorDate: input.paySchedule.anchorDate, projectedDates }
+      : null,
     categoryBreakdown,
     recentExpenses: monthExpenses
       .slice()
@@ -128,11 +152,12 @@ export function buildDashboardSnapshot(input: {
 }
 
 export async function getDashboardSnapshot(month = getCurrentMonthKey()) {
-  const [expenses, paychecks, insight] = await Promise.all([
+  const [expenses, paychecks, insight, paySchedule] = 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(),
   ]);
 
-  return buildDashboardSnapshot({ month, expenses, paychecks, insight });
+  return buildDashboardSnapshot({ month, expenses, paychecks, paySchedule, insight });
 }

src/lib/pay-schedule.ts

@@ -0,0 +1,58 @@
+import { db } from "@/lib/db";
+
+export type PaySchedule = {
+  id: string;
+  amountCents: number;
+  anchorDate: string;
+};
+
+export async function getActiveSchedule(): Promise<PaySchedule | null> {
+  const schedule = await db.paySchedule.findFirst({ where: { active: true }, orderBy: { createdAt: "desc" } });
+  return schedule ?? null;
+}
+
+export async function saveSchedule(amountCents: number, anchorDate: string): Promise<PaySchedule> {
+  await db.paySchedule.updateMany({ where: { active: true }, data: { active: false } });
+  return db.paySchedule.create({ data: { amountCents, anchorDate, active: true } });
+}
+
+export async function clearSchedule(): Promise<void> {
+  await db.paySchedule.updateMany({ where: { active: true }, data: { active: false } });
+}
+
+/**
+ * Returns all biweekly pay dates falling within the given month (YYYY-MM),
+ * anchored to a known pay date.
+ */
+export function getProjectedPayDates(anchorDate: string, month: string): string[] {
+  const [anchorYear, anchorMonth, anchorDay] = anchorDate.split("-").map(Number);
+  const [year, mon] = month.split("-").map(Number);
+
+  // Use UTC-based dates throughout to avoid DST day-shift bugs.
+  const anchorMs = Date.UTC(anchorYear, anchorMonth - 1, anchorDay);
+  const monthStartMs = Date.UTC(year, mon - 1, 1);
+  const monthEndMs = Date.UTC(year, mon, 0); // last day of month (day 0 of next month)
+
+  const MS_PER_DAY = 86_400_000;
+  const period = 14 * MS_PER_DAY;
+
+  // Find the first pay date on or after monthStart that is on the biweekly cycle.
+  const diff = monthStartMs - anchorMs;
+  const periods = Math.floor(diff / period);
+  let current = anchorMs + periods * period;
+  while (current < monthStartMs) {
+    current += period;
+  }
+
+  const results: string[] = [];
+  while (current <= monthEndMs) {
+    const d = new Date(current);
+    const y = d.getUTCFullYear();
+    const m = String(d.getUTCMonth() + 1).padStart(2, "0");
+    const day = String(d.getUTCDate()).padStart(2, "0");
+    results.push(`${y}-${m}-${day}`);
+    current += period;
+  }
+
+  return results;
+}