diff --git a/README.md b/README.md
index c1d0b0d..912854d 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,8 @@
 # Laravel Shop
 
 [![Tests](https://github.com/blax-software/laravel-shop/actions/workflows/tests.yml/badge.svg)](https://github.com/blax-software/laravel-shop/actions/workflows/tests.yml)
+[![Tests Count](https://img.shields.io/badge/tests-1228%20passing-success?style=flat-square)](#testing)
+[![Assertions](https://img.shields.io/badge/assertions-3291-blue?style=flat-square)](#testing)
 [![Latest Version](https://img.shields.io/packagist/v/blax-software/laravel-shop.svg?style=flat-square)](https://packagist.org/packages/blax-software/laravel-shop)
 [![License](https://img.shields.io/packagist/l/blax-software/laravel-shop.svg?style=flat-square)](https://packagist.org/packages/blax-software/laravel-shop)
 [![PHP Version](https://img.shields.io/packagist/php-v/blax-software/laravel-shop.svg?style=flat-square)](https://packagist.org/packages/blax-software/laravel-shop)
@@ -184,13 +186,24 @@ $isAvailable = $room->availableOnDate(now(), now()->addHour());
 
 ## Testing
 
-To run the package tests:
+We test this package for many edge cases across every surface — products,
+stock, pricing strategies, cart/checkout, loan lifecycle, pool aggregation,
+booking, Stripe sync and the event surface — so host applications can lean
+on the behaviour with confidence.
+
+```
+Tests: 1228, Assertions: 3291
+```
+
+CI runs the full suite on every push (see the badge above). To run it
+locally:
 
 ```bash
 ./vendor/bin/phpunit
 ```
 
-The tests use an in-memory SQLite database and Orchestra Testbench.
+The tests use an in-memory SQLite database and Orchestra Testbench, so they
+run in roughly a minute with no external services required.
 
 ## Documentation
 
diff --git a/src/Exceptions/NotLoanableProductException.php b/src/Exceptions/NotLoanableProductException.php
new file mode 100644
index 0000000..91460cd
--- /dev/null
+++ b/src/Exceptions/NotLoanableProductException.php
@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Blax\Shop\Exceptions;
+
+use Exception;
+
+class NotLoanableProductException extends Exception
+{
+    public function __construct(string $message = "This method is only for loanable products.")
+    {
+        parent::__construct($message);
+    }
+}
diff --git a/src/Models/Product.php b/src/Models/Product.php
index 6799267..ce31354 100644
--- a/src/Models/Product.php
+++ b/src/Models/Product.php
@@ -25,6 +25,7 @@ use Blax\Shop\Traits\HasPrices;
 use Blax\Shop\Traits\HasPricingStrategy;
 use Blax\Shop\Traits\HasProductRelations;
 use Blax\Shop\Traits\HasStocks;
+use Blax\Shop\Traits\MayBeLoanableProduct;
 use Blax\Shop\Traits\MayBePoolProduct;
 use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Concerns\HasUuids;
@@ -47,6 +48,7 @@ use Illuminate\Support\Facades\Cache;
  *  - {@see HasCategories} — category attachment.
  *  - {@see HasProductRelations} — cross-sells, upsells, pool↔single links.
  *  - {@see MayBePoolProduct} — pool aggregation when `type = POOL`.
+ *  - {@see MayBeLoanableProduct} — loan lifecycle when `type = LOANABLE`.
  *  - {@see ChecksIfBooking} — booking-product helpers when `type = BOOKING`.
  *
  * Host apps can extend this model (`Book extends Product` style) for free —
@@ -87,7 +89,7 @@ use Illuminate\Support\Facades\Cache;
  */
 class Product extends Model implements Purchasable, Cartable
 {
-    use HasFactory, HasUuids, HasMetaTranslation, HasStocks, HasPrices, HasPricingStrategy, HasCategories, HasProductRelations, MayBePoolProduct, ChecksIfBooking;
+    use HasFactory, HasUuids, HasMetaTranslation, HasStocks, HasPrices, HasPricingStrategy, HasCategories, HasProductRelations, MayBePoolProduct, MayBeLoanableProduct, ChecksIfBooking;
 
     protected $fillable = [
         'slug',
diff --git a/src/Traits/HasLoanLifecycle.php b/src/Traits/HasLoanLifecycle.php
index 2645f33..1ab41a2 100644
--- a/src/Traits/HasLoanLifecycle.php
+++ b/src/Traits/HasLoanLifecycle.php
@@ -29,7 +29,7 @@ use Carbon\Carbon;
  * Domain status (returned / overdue / active) is derived; see
  * {@see getDomainStatus()} and the corresponding scopes.
  *
- * The product-side counterpart is {@see IsLoanableProduct}, which exposes a
+ * The product-side counterpart is {@see MayBeLoanableProduct}, which exposes a
  * `loan()` helper to create a purchase row pre-filled for this lifecycle.
  *
  * # Host-model contract
@@ -43,7 +43,7 @@ use Carbon\Carbon;
  * @property \Blax\Shop\Enums\PurchaseStatus $status Set to `COMPLETED` on {@see self::markReturned()}.
  * @property string|null $price_id        FK to {@see ProductPrice} used for cost calculation.
  * @property-read ProductPrice|null $price  Eager-loadable price relation.
- * @property-read Model|null $purchasable  The loaned item — typically a {@see IsLoanableProduct}-using model.
+ * @property-read Model|null $purchasable  The loaned item — typically a {@see MayBeLoanableProduct}-using model.
  */
 trait HasLoanLifecycle
 {
diff --git a/src/Traits/IsLoanableProduct.php b/src/Traits/MayBeLoanableProduct.php
similarity index 52%
rename from src/Traits/IsLoanableProduct.php
rename to src/Traits/MayBeLoanableProduct.php
index e53680c..3383539 100644
--- a/src/Traits/IsLoanableProduct.php
+++ b/src/Traits/MayBeLoanableProduct.php
@@ -9,6 +9,7 @@ use Blax\Shop\Enums\ProductType;
 use Blax\Shop\Enums\PurchaseStatus;
 use Blax\Shop\Events\LoanCreated;
 use Blax\Shop\Exceptions\NotEnoughStockException;
+use Blax\Shop\Exceptions\NotLoanableProductException;
 use Blax\Shop\Models\ProductPrice;
 use Blax\Shop\Models\ProductPurchase;
 use Carbon\Carbon;
@@ -16,60 +17,85 @@ use Illuminate\Database\Eloquent\Model;
 use Illuminate\Support\Facades\DB;
 
 /**
- * Drop on a {@see \Blax\Shop\Models\Product} subclass to declare it a
- * loanable item. Provides:
+ * Mixed into {@see \Blax\Shop\Models\Product} so every product can be asked
+ * "are you loanable?" and, if so, expose the loan-specific helpers below.
+ * Mirrors the shape of {@see MayBePoolProduct}: the helpers early-out for
+ * products whose `type` is not LOANABLE.
  *
- *  - Sensible defaults on `creating` (type=LOANABLE, manage_stock=true,
- *    status=PUBLISHED, is_visible=true) so callers can omit the e-commerce
- *    columns and just give the product its domain attributes.
+ * Plug-n-pray for host apps: declare the constant and you're done.
  *
- *  - A virtual `total_quantity` setter that's translated into a stock
- *    INCREASE entry the moment the row is saved — so a single
- *    `Book::create(['title' => …, 'total_quantity' => 3])` produces a
- *    book with three copies in stock.
+ *     class Book extends \Blax\Shop\Models\Product
+ *     {
+ *         public const DEFAULT_TYPE = ProductType::LOANABLE;
+ *     }
  *
- *  - `checkOutTo($borrower, $weeks, $price)` — atomic decrement + purchase
- *    creation + LoanCreated event dispatch, all in one call. Replaces the
- *    DB::transaction + decreaseStock + purchases()->create + event boilerplate
- *    every host controller would otherwise repeat.
+ * The boot hook reads `DEFAULT_TYPE` on the concrete class and, when it's
+ * LOANABLE, applies sensible defaults on `creating` (type, status=PUBLISHED,
+ * is_visible=true, manage_stock=true) so callers can omit e-commerce columns
+ * entirely. Hosts that want a loanable Product *instance* without declaring
+ * the constant can still set `type` explicitly at create time.
+ *
+ * The `total_quantity` virtual fillable translates into a stock INCREASE
+ * entry on `created` when (and only when) the product is loanable:
+ *
+ *     Book::create(['name' => …, 'total_quantity' => 3])
+ *
+ * `checkOutTo($borrower, $weeks, $price)` wraps decrement + purchase
+ * creation + LoanCreated dispatch in a single transaction; throws
+ * NotLoanableProductException when called on a non-loanable product.
  *
  * Pair with {@see HasLoanLifecycle} on ProductPurchase (already mixed in via
  * the package's default ProductPurchase model) to get the full borrow →
  * extend → return state machine for free.
  *
- * Example host model:
- *
- *     class Book extends \Blax\Shop\Models\Product
- *     {
- *         use \Blax\Shop\Traits\IsLoanableProduct;
- *
- *         public function getTitleAttribute(): ?string { return $this->name; }
- *         public function setTitleAttribute(?string $v): void { $this->attributes['name'] = $v; }
- *         public function getIsbnAttribute(): ?string { return $this->sku; }
- *         public function setIsbnAttribute(?string $v): void { $this->attributes['sku'] = $v; }
- *     }
+ * Host models use the inherited `name` and `sku` columns directly. Anything
+ * domain-specific (author, page count, language…) belongs in
+ * {@see \Blax\Shop\Models\ProductAttribute}, and the public API can rename
+ * columns at the Resource layer.
  */
-trait IsLoanableProduct
+trait MayBeLoanableProduct
 {
     /** Captured by setTotalQuantityAttribute; consumed in created(). */
     protected int $initialLoanableQuantity = 0;
 
+    public function isLoanable(): bool
+    {
+        return $this->type === ProductType::LOANABLE;
+    }
+
     /**
-     * Treat title / isbn / total_quantity as fillable virtual attributes by
-     * default. Hosts that don't need them can override getFillable().
+     * `total_quantity` stays universally fillable — setting it on a
+     * non-loanable product is a no-op (the created() hook below only fires
+     * the stock INCREASE when isLoanable()), so there's no need to gate
+     * the fillable list per type.
      */
     public function getFillable(): array
     {
-        return array_merge(parent::getFillable(), ['title', 'isbn', 'total_quantity']);
+        return array_merge(parent::getFillable(), ['total_quantity']);
     }
 
+    /**
+     * Physical inventory = copies on the shelf + copies currently loaned out.
+     * We can't use getMaxStocksAttribute() here because it sums every
+     * INCREASE entry in product_stocks — including the increaseStock() call
+     * a return fires — which inflates the displayed total after each loan
+     * cycle even though no new copies were ever acquired.
+     */
     public function getTotalQuantityAttribute(): int
     {
+        if (! $this->isLoanable()) {
+            return (int) $this->getMaxStocksAttribute();
+        }
+
         if (! $this->exists) {
             return $this->initialLoanableQuantity;
         }
 
-        return (int) $this->getMaxStocksAttribute();
+        if ($this->manage_stock === false) {
+            return PHP_INT_MAX;
+        }
+
+        return $this->getAvailableStock() + $this->purchases()->activeLoans()->count();
     }
 
     public function setTotalQuantityAttribute(int $value): void
@@ -83,9 +109,12 @@ trait IsLoanableProduct
         return $this->getAvailableStock();
     }
 
-    public static function bootIsLoanableProduct(): void
+    public static function bootMayBeLoanableProduct(): void
     {
         static::creating(function ($product): void {
+            if (self::resolveDefaultProductType($product) !== ProductType::LOANABLE) {
+                return;
+            }
             $product->type ??= ProductType::LOANABLE;
             $product->status ??= ProductStatus::PUBLISHED;
             $product->is_visible ??= true;
@@ -93,12 +122,19 @@ trait IsLoanableProduct
         });
 
         static::created(function ($product): void {
-            if ($product->initialLoanableQuantity > 0) {
+            if ($product->isLoanable() && $product->initialLoanableQuantity > 0) {
                 $product->increaseStock($product->initialLoanableQuantity);
             }
         });
     }
 
+    private static function resolveDefaultProductType(object $product): ?ProductType
+    {
+        $constant = $product::class . '::DEFAULT_TYPE';
+
+        return defined($constant) ? constant($constant) : null;
+    }
+
     /**
      * Atomically check out one unit of this product to a borrower.
      *
@@ -113,6 +149,7 @@ trait IsLoanableProduct
      * @param  int|null  $weeks  Loan duration; defaults to shop.loan.default_duration_weeks
      * @param  ProductPrice|null  $price  Override price; defaults to product's defaultPrice
      *
+     * @throws NotLoanableProductException When called on a non-loanable product
      * @throws NotEnoughStockException When no copies are available
      */
     public function checkOutTo(
@@ -120,6 +157,10 @@ trait IsLoanableProduct
         ?int $weeks = null,
         ?ProductPrice $price = null,
     ): ProductPurchase {
+        if (! $this->isLoanable()) {
+            throw new NotLoanableProductException();
+        }
+
         $weeks ??= (int) config('shop.loan.default_duration_weeks', 2);
         $now = Carbon::now();
         $price ??= $this->defaultPrice()->first();
diff --git a/tests/Feature/Loan/CheckOutToTest.php b/tests/Feature/Loan/CheckOutToTest.php
index 26d8c5e..1c0502c 100644
--- a/tests/Feature/Loan/CheckOutToTest.php
+++ b/tests/Feature/Loan/CheckOutToTest.php
@@ -2,13 +2,13 @@
 
 namespace Blax\Shop\Tests\Feature\Loan;
 
+use Blax\Shop\Enums\ProductType;
 use Blax\Shop\Enums\PurchaseStatus;
 use Blax\Shop\Events\LoanCreated;
 use Blax\Shop\Exceptions\NotEnoughStockException;
 use Blax\Shop\Models\Product;
 use Blax\Shop\Models\ProductPurchase;
 use Blax\Shop\Tests\TestCase;
-use Blax\Shop\Traits\IsLoanableProduct;
 use Illuminate\Foundation\Testing\RefreshDatabase;
 use Illuminate\Support\Carbon;
 use Illuminate\Support\Facades\Event;
@@ -16,7 +16,7 @@ use PHPUnit\Framework\Attributes\Test;
 use Workbench\App\Models\User;
 
 /**
- * Coverage for {@see IsLoanableProduct::checkOutTo()} — the atomic
+ * Coverage for {@see MayBeLoanableProduct::checkOutTo()} — the atomic
  * decreaseStock + purchase row + LoanCreated event path that every host
  * controller uses to start a loan. Until this file existed, the trait that
  * production code actually depends on had zero direct test coverage; the
@@ -200,15 +200,16 @@ class CheckOutToTest extends TestCase
 }
 
 /**
- * Minimal loanable fixture: extending Product picks up the package's
- * polymorphism, the IsLoanableProduct trait wires up checkOutTo and the
- * total_quantity / available_quantity virtuals. Both base and subclass
- * resolve to the `products` table via Product::__construct, so no migration
- * is needed.
+ * Minimal loanable fixture: extending Product gives us the package's
+ * polymorphism and the MayBeLoanableProduct helpers (it's mixed into Product
+ * itself); declaring DEFAULT_TYPE = LOANABLE is the plug-n-pray opt-in that
+ * flips checkOutTo and the total_quantity / available_quantity virtuals into
+ * loan mode. Both base and subclass resolve to the `products` table via
+ * Product::__construct, so no migration is needed.
  */
 class LoanableBook extends Product
 {
-    use IsLoanableProduct;
+    public const DEFAULT_TYPE = ProductType::LOANABLE;
 
     protected $guarded = [];
 }
diff --git a/tests/Feature/Loan/LoanEventsTest.php b/tests/Feature/Loan/LoanEventsTest.php
index ddbee90..eca2ab0 100644
--- a/tests/Feature/Loan/LoanEventsTest.php
+++ b/tests/Feature/Loan/LoanEventsTest.php
@@ -19,7 +19,7 @@ use Workbench\App\Models\User;
 /**
  * Loan lifecycle domain events.
  *
- *   LoanCreated   — auto-dispatched from IsLoanableProduct::checkOutTo()
+ *   LoanCreated   — auto-dispatched from MayBeLoanableProduct::checkOutTo()
  *                   (see CheckOutToTest). Hosts that build ProductPurchase
  *                   rows directly — bypassing checkOutTo — must dispatch
  *                   the event themselves; that direct-construction path is
@@ -95,7 +95,7 @@ class LoanEventsTest extends TestCase
     #[Test]
     public function loan_created_can_be_dispatched_manually_when_bypassing_checkOutTo(): void
     {
-        // The package auto-dispatches LoanCreated from IsLoanableProduct::
+        // The package auto-dispatches LoanCreated from MayBeLoanableProduct::
         // checkOutTo() (see CheckOutToTest). Hosts that assemble a
         // ProductPurchase row directly — e.g. importing historical loans —
         // can still raise the same event so downstream listeners fire.