Feature: Adding Checkout Services and Events

docs/checkout.md

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+# Checkout — Design Notes
+
+**Status: design finalized, not yet built.** This is the design spec for
+`Modules\Core\Checkout\Services\CheckoutService`, plus the three-stage lifecycle model it's
+part of. Nothing in this document is implemented yet.
+
+---
+
+## Three-stage lifecycle: Cart → Checkout → Order
+
+Each stage is its own concern, not a phase inside a shared one — matching the pattern already
+established this session (`Recovery` was split out from `Cart` specifically because
+abandonment detection is a different lifecycle stage than line-item mutation, even though it
+reads `Cart` state).
+
+- **`Cart`** — line items, coupons, save-for-later (`docs/cart.md`). Ends the moment
+  `Cart::createOrder()` is called.
+- **`Checkout`** — the placement moment itself: setting addresses, selecting a shipping
+  option, placing the order. Starts where Cart ends, ends the instant an `Order` exists.
+  This document.
+- **`Order`** — everything after an order exists: status transitions (`Order::status`,
+  changed via the Filament admin `EditOrder` page — always staff-driven, never part of
+  checkout itself), fulfillment/shipment tracking. **Named and scoped here, not yet built** —
+  same status as `Recovery` before it existed as real code.
+
+`Modules\Core\Checkout\Events\OrderPlaced` (see below) is the handoff point: `Checkout`
+dispatches it the moment an order exists; `Order`'s own listeners (not built yet) would be
+what reacts to it — e.g. sending a confirmation email, initializing whatever `Order` needs to
+initialize. `Checkout` itself has no opinion about what happens after `OrderPlaced` fires.
+
+### Where `Order` would likely absorb work that currently lives under `Shipping`
+
+`Modules\Core\Shipping`'s `Shipment`/`ShipmentInfo` models are already order-scoped
+(`Shipment::order(): BelongsTo`), and `PollShipmentTrackingJob`/
+`ShipmentStatusUpdatedByCarrier` are fulfillment/tracking concerns that happen entirely after
+an order exists — conceptually closer to `Order` than to `Shipping`'s actual job (carrier
+rate quoting, `ShippingRateInterface` drivers, `ShippingManifest`). Not decided whether/when
+this gets moved; noted here so the boundary is visible when `Order` is actually scoped.
+
+---
+
+## `CheckoutService`
+
+Mirrors `Modules\Core\Cart\Services\CartService`'s shape (see `docs/cart.md`) — one
+boboko-owned API a storefront calls, keeping Lunar's own `Cart`/`ShippingManifest` primitives
+an implementation detail.
+
+| Method | Wraps | Dispatches |
+|---|---|---|
+| `setShippingAddress(array\|Addressable $address)` | `Cart::setShippingAddress()` | `ShippingAddressSet($cart, $address)` |
+| `setBillingAddress(array\|Addressable $address)` | `Cart::setBillingAddress()` | `BillingAddressSet($cart, $address)` |
+| `getShippingOptions()` | `ShippingManifest::getOptions($cart)` | — (read-only) |
+| `selectShippingOption(string $identifier)` | `Cart::setShippingOption()` | `ShippingOptionSelected($cart, $option)` — throws `InvalidShippingOptionException` if `$identifier` doesn't resolve |
+| `placeOrder(string $fingerprint)` | `Cart::checkFingerprint()` then `Cart::createOrder()` | `OrderPlaced($order)` |
+
+### `getShippingOptions()` — already fully backed by the merged Shipping-Carriers work
+
+`ShippingManifest::getOptions($cart)` runs every registered `ShippingRateInterface` driver
+through a pipeline — this already includes ACS/Box Now live-rate quoting
+(`Modules\Core\Shipping\Carriers\Acs\AcsRateDriver`/`BoxNowRateDriver`, merged from the
+`Shipping-Carriers` branch) alongside `table-rate-shipping`'s own flat-rate/free-shipping/
+collection drivers. `CheckoutService` doesn't need to build any rate-resolution logic — it's
+a thin pass-through to what already exists and works.
+
+### `placeOrder()` — fingerprint check is mandatory, not optional
+
+`placeOrder(string $fingerprint): Order` requires the fingerprint the shopper's last-seen
+cart total was built from (`Cart::fingerprint()`) as a parameter — not an optional
+after-the-fact check a caller might forget. `Cart::checkFingerprint()` throws Lunar's own
+`FingerprintMismatchException` if the cart's contents/total changed since that fingerprint
+was generated (a line's price changed, stock adjusted the total, another tab modified the
+cart), forcing re-confirmation instead of silently placing an order at a different total than
+what the shopper approved.
+
+### No exception wrapping — same reasoning as `CartService`
+
+Confirmed from source: `Lunar\Validation\Cart\ValidateCartForOrderCreation` (the validator
+`Cart::createOrder()` runs via `config('lunar.cart.validators.order_create')`) already throws
+`Lunar\Exceptions\Carts\CartException` with a field-keyed `MessageBag`
+(`$exception->errors()`) — billing/shipping address completeness, missing shipping option,
+duplicate-order guard. This is already the right shape for a storefront to catch and render
+as form errors directly; wrapping it in a boboko-owned exception type would add indirection
+with identical semantics, the same call made for `CartService`'s cart-line exceptions.
+
+`FingerprintMismatchException` (from the mandatory fingerprint check above) propagates
+as-is for the same reason.
+
+**One genuine exception to this rule**: `selectShippingOption()` throws
+`Modules\Core\Checkout\Exceptions\InvalidShippingOptionException` when `$identifier` doesn't
+resolve to a real option (`ShippingManifest::getOption()` just returns `null` — Lunar has no
+matching exception type here to propagate, unlike `CartException`/`FingerprintMismatchException`
+above). Same reasoning as `Modules\Core\Cart\Exceptions\InvalidCouponException` for
+`Discounts::validateCoupon()`, which also just returns a bool with nothing to reuse. Confirmed
+live: an invalid identifier previously returned the cart unchanged with no signal at all —
+fixed to throw instead, verified via a real container test.
+
+### Validated from source: the real precondition chain
+
+`ValidateCartForOrderCreation::validate()`, read directly from `vendor/lunarphp/core`:
+
+1. No completed order already exists on this cart (duplicate-order guard).
+2. A billing address is set and passes `country_id`/`first_name`/`line_one`/`city`/`postcode`
+   required-field validation.
+3. If the cart `isShippable()` (has at least one non-digital line):
+   - A shipping option must already be selected (`Cart::getShippingOption()` — which only
+     resolves anything once `shippingAddress->shipping_option` has been persisted via
+     `selectShippingOption()`, confirmed from `Lunar\Base\ShippingManifest::getShippingOption()`).
+   - Unless that option is collect/pickup (`$shippingOption->collect`), a shipping address is
+     also required and validated the same way as billing.
+
+This is why `CheckoutService`'s methods exist in the order they're listed above — a
+storefront checkout flow has to drive them roughly in that sequence for `placeOrder()` to
+ever succeed.
+
+---
+
+## Events — richer payload than `CartService`'s, deliberately
+
+`Modules\Core\Checkout\Events`: `ShippingAddressSet`, `BillingAddressSet`,
+`ShippingOptionSelected`, `OrderPlaced`.
+
+Unlike `CartService`'s events (which carry a plain `Cart`/`CartLine` model reference — see
+`docs/cart.md`), these carry richer, already-resolved payload — e.g. `ShippingOptionSelected`
+includes the resolved `ShippingOption` (name, price, carrier identifier), not just the
+string identifier a listener would have to re-resolve. Deliberate divergence from
+`CartService`'s convention: a live-priced shipping quote or a submitted address is
+meaningfully more expensive/awkward for a listener to re-derive later than a `CartLine`
+model reference is.
+
+**Why this matters beyond `Checkout` itself:** the Analytics survey (`docs/scratch/
+analytics-feature-survey.html`) found conversion-funnel tracking (product view → add to cart
+→ checkout → purchase) entirely missing, with zero underlying data captured anywhere. The
+Checkout survey separately flagged "abandoned-checkout stage tracking (email captured vs.
+shipping selected vs. payment started)" as missing. One event per real state transition here
+— not just a single `OrderPlaced` at the end — is what gives a future analytics/reporting
+listener (not built) the funnel-stage data neither gap currently has anything to build on.
+
+**None of these have a listener yet.** Same status as `CartService`'s events — dispatched,
+unconsumed, built so something downstream has a hook to attach to.
+
+---
+
+## Explicitly out of scope for `CheckoutService`
+
+- **Order-status-changed events** — post-placement, staff-driven (`Order::status` changes via
+  the Filament admin `EditOrder` page, never through checkout). Belongs to `Order` (see
+  above), not `Checkout`.
+- **Order confirmation email** — needs `OrderPlaced` as a trigger, but actual sending is
+  separate infrastructure, same "detection/signal only, sending is a later concern" deferral
+  already applied to `Recovery` (`docs/recovery-strategies.md`).
+- **Guest order tracking/lookup** — a separate storefront feature, not part of the placement
+  flow itself.
+- **Payment** — authorizing/capturing a transaction against the placed order. Genuinely
+  separate from `Checkout` as scoped here; `CheckoutService::placeOrder()` produces an
+  `Order`, what happens to pay for it is out of this document's scope.

src/Checkout/Events/BillingAddressSet.php

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+<?php
+
+namespace Modules\Core\Checkout\Events;
+
+use Lunar\Base\Addressable;
+use Lunar\Models\Cart;
+
+/**
+ * Dispatched by CheckoutService::setBillingAddress() — see
+ * ShippingAddressSet's docblock for the full reasoning (Lunar dispatches no
+ * checkout-lifecycle events; this feeds funnel-stage tracking, not built
+ * yet).
+ */
+class BillingAddressSet
+{
+    public function __construct(
+        public readonly Cart $cart,
+        public readonly array|Addressable $address,
+    ) {}
+}

src/Checkout/Events/OrderPlaced.php

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+<?php
+
+namespace Modules\Core\Checkout\Events;
+
+use Lunar\Models\Order;
+
+/**
+ * Dispatched by CheckoutService::placeOrder() the moment an Order exists —
+ * the handoff point between Checkout and Order (see docs/checkout.md's
+ * "Three-stage lifecycle"). Checkout has no opinion about what happens
+ * after this fires; Order's own listeners (not built yet — Order is a
+ * named-but-unscoped concern, same status Recovery had before it existed)
+ * would be what reacts to it — e.g. a confirmation email, initializing
+ * order status tracking.
+ */
+class OrderPlaced
+{
+    public function __construct(
+        public readonly Order $order,
+    ) {}
+}

src/Checkout/Events/ShippingAddressSet.php

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+<?php
+
+namespace Modules\Core\Checkout\Events;
+
+use Lunar\Base\Addressable;
+use Lunar\Models\Cart;
+
+/**
+ * Dispatched by CheckoutService::setShippingAddress() — Lunar itself
+ * dispatches no checkout-lifecycle events at all (same gap CartService's
+ * events fill for cart mutations; see docs/cart.md). Feeds
+ * abandoned-checkout stage tracking / conversion-funnel analytics (neither
+ * built yet — see docs/checkout.md), which is why $address is carried
+ * directly rather than requiring a listener to re-read it off the cart.
+ */
+class ShippingAddressSet
+{
+    public function __construct(
+        public readonly Cart $cart,
+        public readonly array|Addressable $address,
+    ) {}
+}

src/Checkout/Events/ShippingOptionSelected.php

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+<?php
+
+namespace Modules\Core\Checkout\Events;
+
+use Lunar\DataTypes\ShippingOption;
+use Lunar\Models\Cart;
+
+/**
+ * Dispatched by CheckoutService::selectShippingOption() — carries the fully
+ * resolved ShippingOption (name, price, carrier identifier), not just the
+ * string identifier the caller passed in. Deliberate divergence from
+ * CartService's events, which carry a plain Cart/CartLine model reference —
+ * a live-priced carrier quote (see docs/checkout.md's note on
+ * ShippingManifest::getOptions() already being backed by the merged
+ * Shipping-Carriers ACS/Box Now live-rate drivers) is meaningfully more
+ * expensive for a listener to re-derive later than a CartLine reference is.
+ */
+class ShippingOptionSelected
+{
+    public function __construct(
+        public readonly Cart $cart,
+        public readonly ShippingOption $option,
+    ) {}
+}

src/Checkout/Exceptions/InvalidShippingOptionException.php

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+<?php
+
+namespace Modules\Core\Checkout\Exceptions;
+
+use RuntimeException;
+
+/**
+ * Thrown by CheckoutService::selectShippingOption() when the given
+ * identifier doesn't resolve to a real, currently-available ShippingOption
+ * for the cart — Lunar's own ShippingManifest::getOption() just returns
+ * null, it has no matching exception type of its own to reuse here (same
+ * reasoning as Modules\Core\Cart\Exceptions\InvalidCouponException for
+ * Discounts::validateCoupon()).
+ */
+class InvalidShippingOptionException extends RuntimeException
+{
+    public function __construct(public readonly string $identifier)
+    {
+        parent::__construct("The shipping option \"{$identifier}\" is not available for this cart.");
+    }
+}

src/Checkout/Services/CheckoutService.php

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+<?php
+
+namespace Modules\Core\Checkout\Services;
+
+use Illuminate\Support\Collection;
+use Illuminate\Support\Facades\Event;
+use Lunar\Base\Addressable;
+use Lunar\DataTypes\ShippingOption;
+use Lunar\Facades\ShippingManifest;
+use Lunar\Models\Cart;
+use Lunar\Models\Order;
+use Modules\Core\Cart\Services\CartService;
+use Modules\Core\Checkout\Events\BillingAddressSet;
+use Modules\Core\Checkout\Events\OrderPlaced;
+use Modules\Core\Checkout\Events\ShippingAddressSet;
+use Modules\Core\Checkout\Events\ShippingOptionSelected;
+use Modules\Core\Checkout\Exceptions\InvalidShippingOptionException;
+
+/**
+ * Storefront-facing checkout operations, mirroring
+ * Modules\Core\Cart\Services\CartService's shape — one boboko-owned API a
+ * storefront calls, keeping Lunar's own Cart/ShippingManifest primitives an
+ * implementation detail. See docs/checkout.md for the full design —
+ * Checkout is the middle of a three-stage lifecycle (Cart → Checkout →
+ * Order): it owns the placement moment itself (address, shipping selection,
+ * placeOrder()) and ends the instant an Order exists. What happens to that
+ * Order afterward (status transitions, fulfillment) is deliberately out of
+ * scope here — see OrderPlaced's docblock.
+ *
+ * Depends on CartService for cart access rather than reaching into
+ * Lunar\Facades\CartSession directly a second time, so Checkout stays
+ * layered on top of Cart's own service boundary instead of duplicating it.
+ */
+class CheckoutService
+{
+    public function __construct(
+        private readonly CartService $cart,
+    ) {}
+
+    public function setShippingAddress(array|Addressable $address): Cart
+    {
+        $cart = $this->cart->currentOrCreate()->setShippingAddress($address);
+
+        Event::dispatch(new ShippingAddressSet($cart, $address));
+
+        return $cart;
+    }
+
+    public function setBillingAddress(array|Addressable $address): Cart
+    {
+        $cart = $this->cart->currentOrCreate()->setBillingAddress($address);
+
+        Event::dispatch(new BillingAddressSet($cart, $address));
+
+        return $cart;
+    }
+
+    /**
+     * Every shipping option currently available for the cart — already
+     * fully backed by the merged Shipping-Carriers work: this runs every
+     * registered Lunar\Shipping\Interfaces\ShippingRateInterface driver
+     * (ACS/Box Now live-rate quoting alongside table-rate-shipping's own
+     * flat-rate/free-shipping/collection drivers) through
+     * ShippingManifest's pipeline. No rate-resolution logic lives here —
+     * this is a thin pass-through.
+     *
+     * @return Collection<int, ShippingOption>
+     */
+    public function getShippingOptions(): Collection
+    {
+        return ShippingManifest::getOptions($this->cart->currentOrCreate());
+    }
+
+    /**
+     * @throws InvalidShippingOptionException if $identifier doesn't resolve
+     *   to a real, currently-available option for the cart
+     */
+    public function selectShippingOption(string $identifier): Cart
+    {
+        $cartBefore = $this->cart->currentOrCreate();
+        $option = ShippingManifest::getOption($cartBefore, $identifier);
+
+        if ($option === null) {
+            throw new InvalidShippingOptionException($identifier);
+        }
+
+        $cart = $cartBefore->setShippingOption($option);
+
+        Event::dispatch(new ShippingOptionSelected($cart, $option));
+
+        return $cart;
+    }
+
+    /**
+     * $fingerprint is mandatory, not optional — the caller must prove the
+     * cart total the shopper last saw (Cart::fingerprint()) still matches
+     * before an order is placed. Cart::checkFingerprint() throws Lunar's own
+     * FingerprintMismatchException on a mismatch (a line's price changed,
+     * stock adjusted the total, another tab modified the cart) rather than
+     * silently placing an order at a different total than what was shown.
+     *
+     * No exception wrapping: Lunar\Validation\Cart\ValidateCartForOrderCreation
+     * (run inside Cart::createOrder()) already throws
+     * Lunar\Exceptions\Carts\CartException with a field-keyed MessageBag
+     * ($exception->errors()) for address/shipping-option validation and the
+     * duplicate-order guard — already the right shape for a storefront to
+     * render as form errors directly. FingerprintMismatchException
+     * propagates the same way, for the same reason.
+     *
+     * @throws \Lunar\Exceptions\FingerprintMismatchException
+     * @throws \Lunar\Exceptions\Carts\CartException
+     */
+    public function placeOrder(string $fingerprint): Order
+    {
+        $cart = $this->cart->currentOrCreate();
+        $cart->checkFingerprint($fingerprint);
+
+        $order = $cart->createOrder();
+
+        Event::dispatch(new OrderPlaced($order));
+
+        return $order;
+    }
+}