Phase4: Stripe

src/components/billing/customer-invoice-detail.tsx

@@ -1,6 +1,8 @@
 import { useTranslations, useFormatter } from "next-intl";
 import { Card } from "@/components/ui/card";
 import type { Invoice, InvoiceLine } from "@/types";
+import { PayInvoiceButton } from "./pay-invoice-button";
+import { PaymentStatusBanner } from "./payment-status-banner";
 
 interface Props {
   invoice: Invoice;
@@ -29,6 +31,7 @@ export function CustomerInvoiceDetail({ invoice, lines }: Props) {
 
   return (
     <div className="space-y-6 animate-in">
+      <PaymentStatusBanner />
       <div className="flex items-start justify-between gap-4 flex-wrap">
         <div>
           <div className="flex items-center gap-3 mb-2">
@@ -49,14 +52,23 @@ export function CustomerInvoiceDetail({ invoice, lines }: Props) {
             {fmt.dateTime(new Date(invoice.periodEnd), { dateStyle: "long" })}
           </p>
         </div>
-        <a
-          href={`/api/billing/invoices/${encodeURIComponent(invoice.invoiceNumber)}/pdf`}
-          target="_blank"
-          rel="noopener noreferrer"
-          className="px-4 py-2 rounded-md bg-accent text-white text-sm font-medium hover:bg-accent-dim transition-colors"
-        >
-          {t("downloadPdf")}
-        </a>
+        <div className="flex items-start gap-2 flex-wrap">
+          {/* Phase 4: Pay-with-card available for open + overdue.
+              Paid/void/draft/uncollectible hide the button — the
+              API also enforces this, so client-side hiding is just
+              for the visible affordance. */}
+          {(invoice.status === "open" || invoice.status === "overdue") && (
+            <PayInvoiceButton invoiceNumber={invoice.invoiceNumber} />
+          )}
+          <a
+            href={`/api/billing/invoices/${encodeURIComponent(invoice.invoiceNumber)}/pdf`}
+            target="_blank"
+            rel="noopener noreferrer"
+            className="px-4 py-2 rounded-md bg-surface-3 hover:bg-surface-2 border border-border text-sm font-medium transition-colors"
+          >
+            {t("downloadPdf")}
+          </a>
+        </div>
       </div>
 
       <Card>

src/components/billing/pay-invoice-button.tsx

@@ -0,0 +1,64 @@
+"use client";
+
+import { useState } from "react";
+import { useTranslations } from "next-intl";
+
+interface Props {
+  invoiceNumber: string;
+}
+
+/**
+ * Pay-with-card button. Posts to /api/billing/invoices/[n]/pay,
+ * which returns a Stripe Checkout Session URL; we redirect the
+ * browser there.
+ *
+ * The button is rendered only by the parent for status='open' or
+ * 'overdue' invoices — the API enforces this too, but pre-filtering
+ * UI-side keeps the dead state out of the customer's face.
+ */
+export function PayInvoiceButton({ invoiceNumber }: Props) {
+  const t = useTranslations("customerBilling");
+  const [busy, setBusy] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+
+  const onClick = async () => {
+    setBusy(true);
+    setError(null);
+    try {
+      const res = await fetch(
+        `/api/billing/invoices/${encodeURIComponent(invoiceNumber)}/pay`,
+        { method: "POST" }
+      );
+      const data = await res.json().catch(() => ({}));
+      if (!res.ok) {
+        throw new Error(data.error ?? `HTTP ${res.status}`);
+      }
+      if (!data.url) {
+        throw new Error("Payment session URL missing from response.");
+      }
+      // Hard navigation, not Next.js router — Stripe Checkout is a
+      // separate origin and the browser needs to fully leave our app.
+      window.location.href = data.url;
+    } catch (e: any) {
+      setError(e?.message ?? String(e));
+      setBusy(false);
+    }
+  };
+
+  return (
+    <div className="flex flex-col items-end gap-1">
+      <button
+        onClick={onClick}
+        disabled={busy}
+        className="px-4 py-2 rounded-md bg-accent text-white text-sm font-medium hover:bg-accent-dim transition-colors disabled:opacity-50 cursor-pointer"
+      >
+        {busy ? t("redirectingToStripe") : t("payWithCard")}
+      </button>
+      {error && (
+        <span className="text-xs text-error max-w-[260px] text-right">
+          {error}
+        </span>
+      )}
+    </div>
+  );
+}

src/components/billing/payment-status-banner.tsx

@@ -0,0 +1,66 @@
+"use client";
+
+import { useEffect, useState } from "react";
+import { useRouter } from "next/navigation";
+import { useTranslations } from "next-intl";
+
+/**
+ * Banner shown after a return from Stripe Checkout.
+ *
+ *   ?paid=1       → green success banner. The webhook may or may
+ *                   not have processed yet, so we phrase the message
+ *                   as "Payment received, status will update shortly"
+ *                   and don't claim the status is already paid. A
+ *                   light auto-refresh after a few seconds nudges
+ *                   the page to pick up the new status badge.
+ *
+ *   ?cancelled=1  → neutral grey banner: "Payment cancelled". The
+ *                   invoice stays in 'open' state.
+ *
+ * The banner cleans up the query params from the URL so a page
+ * reload doesn't repeat the message. We use router.replace() to
+ * keep history clean.
+ */
+export function PaymentStatusBanner() {
+  const router = useRouter();
+  const t = useTranslations("customerBilling");
+  const [state, setState] = useState<"paid" | "cancelled" | null>(null);
+
+  useEffect(() => {
+    const params = new URLSearchParams(window.location.search);
+    if (params.has("paid")) {
+      setState("paid");
+      // Reload after 4s so the status badge picks up the webhook's
+      // effect on the invoice row. By then most webhook deliveries
+      // have landed; if not the user just sees "open" and can
+      // manually refresh.
+      const timer = setTimeout(() => {
+        router.refresh();
+      }, 4000);
+      // Strip the query string out of the URL.
+      const cleanUrl = window.location.pathname;
+      window.history.replaceState({}, "", cleanUrl);
+      return () => clearTimeout(timer);
+    } else if (params.has("cancelled")) {
+      setState("cancelled");
+      const cleanUrl = window.location.pathname;
+      window.history.replaceState({}, "", cleanUrl);
+    }
+  }, [router]);
+
+  if (state === "paid") {
+    return (
+      <div className="mb-4 p-3 rounded-md border border-success bg-success/10 text-sm text-success">
+        {t("paymentReceived")}
+      </div>
+    );
+  }
+  if (state === "cancelled") {
+    return (
+      <div className="mb-4 p-3 rounded-md border border-border bg-surface-2 text-sm text-text-secondary">
+        {t("paymentCancelled")}
+      </div>
+    );
+  }
+  return null;
+}