Add: Shipping selector component and checkout integration

Added ShippingSelector component that:
- Displays country selection dropdown
- Fetches available Royal Mail shipping quotes based on cart weight
- Shows delivery estimates and international delivery warnings
- Lets customers select preferred shipping service
- Auto-selects cheapest option by default

Integrated into checkout:
- Shows shipping selector in both logged-in and guest flows
- Displays shipping cost breakdown in order summary
- Passes shipping country and service to checkout API
- Validates shipping selection before processing payment

.claude/settings.local.json

@@ -87,7 +87,8 @@
       "Bash(git commit -m 'Refactor: Move start design server action to separate file *)",
       "Bash(git commit -m 'Add: Prominent '\\\\''Shop plain items'\\\\'' section to homepage *)",
       "Bash(git commit -m 'Feature: Royal Mail shipping integration with weight-based postage *)",
-      "Bash(git commit -m 'Add: Weight field to product admin pages *)"
+      "Bash(git commit -m 'Add: Weight field to product admin pages *)",
+      "Bash(git commit -m 'Add: Shipping selector component and checkout integration *)"
     ]
   }
 }

src/app/checkout/client.tsx

@@ -5,6 +5,7 @@ import Link from 'next/link';
 import { useCart } from '@/lib/cartStore';
 import { loginCustomer } from '@/app/account/actions';
 import Price from '@/components/Price';
+import ShippingSelector from '@/components/ShippingSelector';
 
 interface CheckoutPageClientProps {
   isLoggedIn: boolean;
@@ -16,6 +17,9 @@ export default function CheckoutPageClient({ isLoggedIn, customer }: CheckoutPag
   const [mode, setMode] = useState<'logged-in' | 'login' | 'guest' | null>(isLoggedIn ? 'logged-in' : null);
   const [checkingOut, setCheckingOut] = useState(false);
   const [checkoutError, setCheckoutError] = useState<string | null>(null);
+  const [shippingCountry, setShippingCountry] = useState('GB');
+  const [shippingService, setShippingService] = useState<string | null>(null);
+  const [shippingCost, setShippingCost] = useState(0);
   const [guestData, setGuestData] = useState({
     fullName: '',
     email: '',
@@ -24,7 +28,8 @@ export default function CheckoutPageClient({ isLoggedIn, customer }: CheckoutPag
   });
 
   const items = useCart((s) => s.items);
-  const total = useCart((s) => s.total());
+  const subtotal = useCart((s) => s.total());
+  const total = subtotal + shippingCost;
 
   useEffect(() => setMounted(true), []);
 
@@ -51,6 +56,10 @@ export default function CheckoutPageClient({ isLoggedIn, customer }: CheckoutPag
       setCheckoutError('Please fill in all fields.');
       return;
     }
+    if (!shippingService) {
+      setCheckoutError('Please select a shipping method.');
+      return;
+    }
 
     setCheckingOut(true);
     setCheckoutError(null);
@@ -71,6 +80,8 @@ export default function CheckoutPageClient({ isLoggedIn, customer }: CheckoutPag
             phone: guestData.phone,
             address: guestData.address,
           },
+          shippingCountry,
+          shippingService,
         }),
       });
       const data = await res.json();
@@ -106,8 +117,18 @@ export default function CheckoutPageClient({ isLoggedIn, customer }: CheckoutPag
               </div>
             ))}
           </div>
-          <div className="mt-4 border-t border-line pt-4">
-            <div className="flex justify-between font-display text-lg">
+          <div className="mt-4 border-t border-line pt-4 space-y-2">
+            <div className="flex justify-between text-sm">
+              <span>Subtotal</span>
+              <Price cents={subtotal} className="font-mono" />
+            </div>
+            {shippingCost > 0 && (
+              <div className="flex justify-between text-sm">
+                <span>Shipping ({shippingService})</span>
+                <Price cents={shippingCost} className="font-mono" />
+              </div>
+            )}
+            <div className="flex justify-between font-display text-lg pt-2 border-t border-line">
               <span>Total</span>
               <Price cents={total} className="font-mono" />
             </div>
@@ -117,11 +138,28 @@ export default function CheckoutPageClient({ isLoggedIn, customer }: CheckoutPag
         {/* Checkout options */}
         <div>
           {mode === 'logged-in' ? (
-            <div>
-              <h3 className="font-display text-lg">Ready to checkout</h3>
-              <p className="mt-2 text-sm text-muted">Logged in as {customer?.email}</p>
+            <div className="space-y-6">
+              <div>
+                <h3 className="font-display text-lg">Ready to checkout</h3>
+                <p className="mt-2 text-sm text-muted">Logged in as {customer?.email}</p>
+              </div>
+
+              <ShippingSelector
+                items={items}
+                onShippingSelect={(country, service, cost) => {
+                  setShippingCountry(country);
+                  setShippingService(service);
+                  setShippingCost(cost);
+                }}
+              />
+
               <button
                 onClick={async () => {
+                  if (!shippingService) {
+                    setCheckoutError('Please select a shipping method.');
+                    return;
+                  }
+
                   console.log('💳 Checkout button clicked, cart items:', items.length);
                   setCheckingOut(true);
                   setCheckoutError(null);
@@ -137,7 +175,12 @@ export default function CheckoutPageClient({ isLoggedIn, customer }: CheckoutPag
                     const res = await fetch('/api/checkout', {
                       method: 'POST',
                       headers: { 'Content-Type': 'application/json' },
-                      body: JSON.stringify({ items, customerId: customer.id }),
+                      body: JSON.stringify({
+                        items,
+                        customerId: customer.id,
+                        shippingCountry,
+                        shippingService,
+                      }),
                     });
                     const data = await res.json();
                     console.log('📦 Checkout response:', { status: res.status, ok: res.ok, hasUrl: !!data.url });
@@ -296,6 +339,16 @@ export default function CheckoutPageClient({ isLoggedIn, customer }: CheckoutPag
                     className="w-full border border-line px-3 py-2 text-sm"
                   />
                 </div>
+
+                <ShippingSelector
+                  items={items}
+                  onShippingSelect={(country, service, cost) => {
+                    setShippingCountry(country);
+                    setShippingService(service);
+                    setShippingCost(cost);
+                  }}
+                />
+
                 <button
                   type="submit"
                   disabled={checkingOut}

src/components/ShippingSelector.tsx

@@ -0,0 +1,141 @@
+'use client';
+
+import { useEffect, useState } from 'react';
+import type { ShippingQuote } from '@/lib/royalmail-shipping';
+import { formatShippingPrice, getDeliveryEstimate } from '@/lib/royalmail-shipping';
+
+interface CartItem {
+  productId: string;
+  quantity: number;
+}
+
+interface ShippingSelectorProps {
+  items: CartItem[];
+  onShippingSelect: (country: string, service: string, cost: number) => void;
+}
+
+export default function ShippingSelector({ items, onShippingSelect }: ShippingSelectorProps) {
+  const [country, setCountry] = useState('GB');
+  const [quotes, setQuotes] = useState<ShippingQuote[]>([]);
+  const [selectedService, setSelectedService] = useState<string | null>(null);
+  const [loading, setLoading] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+  const [totalWeight, setTotalWeight] = useState<string | null>(null);
+
+  // Fetch shipping quotes when country changes
+  useEffect(() => {
+    async function fetchQuotes() {
+      if (!items.length) return;
+
+      setLoading(true);
+      setError(null);
+
+      try {
+        const res = await fetch('/api/checkout/shipping-quotes', {
+          method: 'POST',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify({ items, country }),
+        });
+
+        const data = await res.json();
+
+        if (!res.ok) {
+          throw new Error(data.error || 'Failed to fetch shipping quotes');
+        }
+
+        setQuotes(data.quotes);
+        setTotalWeight(data.totalWeightKg);
+
+        // Auto-select the first (cheapest) option
+        if (data.quotes.length > 0) {
+          const firstService = data.quotes[0];
+          setSelectedService(firstService.service);
+          onShippingSelect(country, firstService.service, firstService.price);
+        }
+      } catch (err) {
+        setError(err instanceof Error ? err.message : 'Failed to fetch shipping quotes');
+        setQuotes([]);
+      } finally {
+        setLoading(false);
+      }
+    }
+
+    fetchQuotes();
+  }, [items, country, onShippingSelect]);
+
+  const selectedQuote = quotes.find((q) => q.service === selectedService);
+
+  return (
+    <div className="space-y-4 border border-line bg-surface p-6">
+      <div>
+        <p className="tag-label mb-2 block">Shipping to</p>
+        <select
+          value={country}
+          onChange={(e) => setCountry(e.target.value)}
+          className="w-full border border-line bg-paper px-3 py-2 text-sm"
+        >
+          {/* Common destinations */}
+          <option value="GB">United Kingdom</option>
+          <option value="IE">Ireland</option>
+          <option value="US">United States</option>
+          <option value="CA">Canada</option>
+          <option value="AU">Australia</option>
+          <option value="NZ">New Zealand</option>
+          <option value="DE">Germany</option>
+          <option value="FR">France</option>
+          <option value="NL">Netherlands</option>
+          <option value="ES">Spain</option>
+          <option value="IT">Italy</option>
+          <option value="JP">Japan</option>
+        </select>
+      </div>
+
+      {totalWeight && (
+        <p className="text-xs text-muted">
+          Total weight: <strong>{totalWeight} kg</strong>
+        </p>
+      )}
+
+      {loading ? (
+        <p className="text-sm text-muted">Loading shipping options...</p>
+      ) : error ? (
+        <p className="text-sm text-splash-pink">{error}</p>
+      ) : quotes.length === 0 ? (
+        <p className="text-sm text-muted">No shipping options available for this destination.</p>
+      ) : (
+        <div>
+          <p className="tag-label mb-3 block">Delivery method</p>
+          <div className="space-y-3">
+            {quotes.map((quote) => (
+              <label key={quote.service} className="flex items-start gap-3 border border-line p-3 cursor-pointer hover:bg-paper/50">
+                <input
+                  type="radio"
+                  name="shipping-service"
+                  value={quote.service}
+                  checked={selectedService === quote.service}
+                  onChange={() => {
+                    setSelectedService(quote.service);
+                    onShippingSelect(country, quote.service, quote.price);
+                  }}
+                  className="mt-1 h-4 w-4 accent-clay"
+                />
+                <div className="flex-1">
+                  <div className="flex items-baseline justify-between">
+                    <p className="font-medium text-sm">{quote.service}</p>
+                    <p className="font-mono text-sm font-medium">{formatShippingPrice(quote.price)}</p>
+                  </div>
+                  <p className="mt-1 text-xs text-muted">{getDeliveryEstimate(quote)}</p>
+                  {quote.warning && (
+                    <p className="mt-2 text-xs text-splash-orange">
+                      ⚠️ {quote.warning}
+                    </p>
+                  )}
+                </div>
+              </label>
+            ))}
+          </div>
+        </div>
+      )}
+    </div>
+  );
+}