feat: implement stock mutation functionality with service and controller; add pagination and UI components

app/Http/Controllers/Admin/Master/Product/StockMutationController.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace App\Http\Controllers\Admin\Master\Product;
+
+use App\Http\Controllers\Controller;
+use App\Http\Requests\StockMutationRequest;
+use App\Models\Product;
+use App\Models\ProductVariant;
+use App\Services\StockMutationService;
+use Inertia\Inertia;
+use Inertia\Response;
+
+class StockMutationController extends Controller
+{
+    public function __construct(
+        private StockMutationService $service = new StockMutationService,
+    ) {}
+
+    public function index(StockMutationRequest $request, Product $product, ProductVariant $variant): Response
+    {
+        $perPage = $request->validatedWithDefaults()['perPage'];
+
+        return Inertia::render('admin/master/product/variant/stock-mutations', [
+            'product' => [
+                'id' => $product->id,
+                'name' => $product->name,
+            ],
+            'variant' => [
+                'id' => $variant->id,
+                'name' => $variant->name,
+            ],
+            'mutations' => $this->service->paginated($variant, $perPage),
+        ]);
+    }
+}

app/Http/Requests/StockMutationRequest.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace App\Http\Requests;
+
+use Illuminate\Foundation\Http\FormRequest;
+
+class StockMutationRequest extends FormRequest
+{
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    public function rules(): array
+    {
+        return [
+            'per_page' => ['nullable', 'integer', 'min:1', 'max:100'],
+        ];
+    }
+
+    public function validatedWithDefaults(): array
+    {
+        $validated = $this->validated();
+
+        return [
+            'perPage' => $validated['per_page'] ?? 20,
+        ];
+    }
+}

app/Services/Admin/Master/Product/ProductService.php

@@ -7,6 +7,7 @@
 use App\Models\ProductVariant;
 use App\Services\NotificationService;
 use App\Services\S3PresignedService;
+use App\Services\StockMutationService;
 use Illuminate\Contracts\Pagination\LengthAwarePaginator;
 use Illuminate\Database\Eloquent\Collection;
 use Illuminate\Support\Facades\DB;
@@ -16,6 +17,7 @@ class ProductService
     public function __construct(
         private ProductVariantService $variantService = new ProductVariantService,
         private S3PresignedService $s3Service = new S3PresignedService,
+        private StockMutationService $stockMutationService = new StockMutationService,
     ) {}
 
     public function getAll(array $filters = []): Collection
@@ -111,6 +113,8 @@ public function create(array $data): Product
                 if (! empty($variantData['photo_keys']) && is_array($variantData['photo_keys'])) {
                     $this->variantService->registerPhotos($variant, $variantData['photo_keys']);
                 }
+
+                $this->stockMutationService->recordInitial($variant, $variantData, 'Stok awal saat pembuatan varian');
             }
 
             return $product;
@@ -195,12 +199,14 @@ public function update(Product $product, array $data): Product
 
                 if ($variantId) {
                     $variant = $product->productVariants()->findOrFail($variantId);
+                    $oldData = $variant->only(['stock', 'reject_stock', 'retail_stock']);
                     $variant->update([
                         'name' => $variantData['name'],
                         'stock' => $variantData['stock'],
                         'reject_stock' => $variantData['reject_stock'],
                         'retail_stock' => $variantData['retail_stock'],
                     ]);
+                    $this->stockMutationService->recordAdjustment($variant, $oldData, $variantData, 'Penyesuaian stok saat edit varian');
                 } else {
                     $variant = $product->productVariants()->create([
                         'name' => $variantData['name'],
@@ -208,6 +214,7 @@ public function update(Product $product, array $data): Product
                         'reject_stock' => $variantData['reject_stock'],
                         'retail_stock' => $variantData['retail_stock'],
                     ]);
+                    $this->stockMutationService->recordInitial($variant, $variantData, 'Stok awal saat pembuatan varian');
                 }
 
                 $variant->productPrices()->delete();

app/Services/Admin/Master/Product/ProductVariantService.php

@@ -5,10 +5,10 @@
 use App\Models\Product;
 use App\Models\ProductPrice;
 use App\Models\ProductVariant;
-use App\Models\StockMutation;
 use App\Services\Concerns\RegistersMedia;
 use App\Services\NotificationService;
 use App\Services\S3PresignedService;
+use App\Services\StockMutationService;
 use Illuminate\Support\Facades\DB;
 use Illuminate\Validation\ValidationException;
 
@@ -18,6 +18,7 @@ class ProductVariantService
 
     public function __construct(
         private S3PresignedService $s3Service = new S3PresignedService,
+        private StockMutationService $stockMutationService = new StockMutationService,
     ) {}
 
     public function getForEdit(ProductVariant $variant): array
@@ -47,6 +48,8 @@ public function getForEdit(ProductVariant $variant): array
     public function update(ProductVariant $variant, array $data): ProductVariant
     {
         DB::transaction(function () use ($variant, $data) {
+            $oldData = $variant->only(['stock', 'reject_stock', 'retail_stock']);
+
             $variant->update([
                 'name' => $data['name'],
                 'stock' => $data['stock'],
@@ -54,6 +57,8 @@ public function update(ProductVariant $variant, array $data): ProductVariant
                 'retail_stock' => $data['retail_stock'],
             ]);
 
+            $this->stockMutationService->recordAdjustment($variant, $oldData, $data, 'Penyesuaian stok saat edit varian');
+
             $variant->productPrices()->delete();
 
             foreach ($data['prices'] as $priceData) {
@@ -137,29 +142,15 @@ public function transferStock(ProductVariant $variant, array $data): ProductVari
                 'retail_stock' => $retailBefore + $quantity,
             ]);
 
-            StockMutation::create([
-                'user_id' => auth()->id(),
-                'stockable_type' => ProductVariant::class,
-                'stockable_id' => $variant->id,
-                'type' => 'out',
-                'quantity' => -$quantity,
-                'stock_before' => $stockBefore,
-                'stock_after' => $stockBefore - $quantity,
-                'stock_quality' => 'good',
-                'description' => $data['description'] ?? 'Transfer stok bagus ke stok ecer',
-            ]);
-
-            StockMutation::create([
-                'user_id' => auth()->id(),
-                'stockable_type' => ProductVariant::class,
-                'stockable_id' => $variant->id,
-                'type' => 'in',
-                'quantity' => $quantity,
-                'stock_before' => $retailBefore,
-                'stock_after' => $retailBefore + $quantity,
-                'stock_quality' => 'retail',
-                'description' => $data['description'] ?? 'Transfer stok bagus ke stok ecer',
-            ]);
+            $this->stockMutationService->recordTransfer(
+                model: $variant,
+                quantity: $quantity,
+                fromQuality: 'good',
+                toQuality: 'retail',
+                fromBefore: $stockBefore,
+                toBefore: $retailBefore,
+                description: $data['description'] ?? 'Transfer stok bagus ke stok ecer',
+            );
         });
 
         NotificationService::notify(

app/Services/StockMutationService.php

@@ -0,0 +1,109 @@
+<?php
+
+namespace App\Services;
+
+use App\Models\StockMutation;
+use Illuminate\Contracts\Pagination\LengthAwarePaginator;
+use Illuminate\Database\Eloquent\Model;
+
+class StockMutationService
+{
+    private const QUALITY_MAP = [
+        'stock' => 'good',
+        'reject_stock' => 'reject',
+        'retail_stock' => 'retail',
+    ];
+
+    public function recordInitial(Model $model, array $stockData, string $description = 'Stok awal'): void
+    {
+        $userId = auth()->id();
+
+        foreach (self::QUALITY_MAP as $field => $quality) {
+            $quantity = (int) ($stockData[$field] ?? 0);
+            if ($quantity > 0) {
+                StockMutation::create([
+                    'user_id' => $userId,
+                    'stockable_type' => get_class($model),
+                    'stockable_id' => $model->id,
+                    'type' => 'in',
+                    'quantity' => $quantity,
+                    'stock_before' => 0,
+                    'stock_after' => $quantity,
+                    'stock_quality' => $quality,
+                    'description' => $description,
+                ]);
+            }
+        }
+    }
+
+    public function recordAdjustment(Model $model, array $oldData, array $newData, string $description = 'Penyesuaian stok'): void
+    {
+        $userId = auth()->id();
+
+        foreach (self::QUALITY_MAP as $field => $quality) {
+            $old = (int) ($oldData[$field] ?? 0);
+            $new = (int) ($newData[$field] ?? 0);
+            $diff = $new - $old;
+
+            if ($diff !== 0) {
+                StockMutation::create([
+                    'user_id' => $userId,
+                    'stockable_type' => get_class($model),
+                    'stockable_id' => $model->id,
+                    'type' => $diff > 0 ? 'in' : 'out',
+                    'quantity' => $diff,
+                    'stock_before' => $old,
+                    'stock_after' => $new,
+                    'stock_quality' => $quality,
+                    'description' => $description,
+                ]);
+            }
+        }
+    }
+
+    public function recordTransfer(
+        Model $model,
+        int $quantity,
+        string $fromQuality,
+        string $toQuality,
+        int $fromBefore,
+        int $toBefore,
+        string $description = 'Transfer stok',
+    ): void {
+        $userId = auth()->id();
+
+        StockMutation::create([
+            'user_id' => $userId,
+            'stockable_type' => get_class($model),
+            'stockable_id' => $model->id,
+            'type' => 'out',
+            'quantity' => -$quantity,
+            'stock_before' => $fromBefore,
+            'stock_after' => $fromBefore - $quantity,
+            'stock_quality' => $fromQuality,
+            'description' => $description,
+        ]);
+
+        StockMutation::create([
+            'user_id' => $userId,
+            'stockable_type' => get_class($model),
+            'stockable_id' => $model->id,
+            'type' => 'in',
+            'quantity' => $quantity,
+            'stock_before' => $toBefore,
+            'stock_after' => $toBefore + $quantity,
+            'stock_quality' => $toQuality,
+            'description' => $description,
+        ]);
+    }
+
+    public function paginated(Model $model, int $perPage = 20): LengthAwarePaginator
+    {
+        return StockMutation::query()
+            ->where('stockable_type', get_class($model))
+            ->where('stockable_id', $model->id)
+            ->with('user:id,username,email')
+            ->latest()
+            ->paginate($perPage);
+    }
+}

resources/js/hooks/use-infinite-scroll.ts

@@ -0,0 +1,88 @@
+import { router } from '@inertiajs/react';
+import { useCallback, useEffect, useRef, useState } from 'react';
+
+type PaginatedData<T> = {
+    data: T[];
+    current_page: number;
+    last_page: number;
+    per_page: number;
+    total: number;
+};
+
+type UseInfiniteScrollOptions<T> = {
+    initialData: PaginatedData<T>;
+    fetchUrl: string;
+    perPage?: number;
+};
+
+export function useInfiniteScroll<T>({
+    initialData,
+    fetchUrl,
+    perPage = 20,
+}: UseInfiniteScrollOptions<T>) {
+    const [items, setItems] = useState<T[]>(initialData.data);
+    const [currentPage, setCurrentPage] = useState(initialData.current_page);
+    const [lastPage, setLastPage] = useState(initialData.last_page);
+    const [loading, setLoading] = useState(false);
+    const sentinelRef = useRef<HTMLDivElement | null>(null);
+
+    const loadMore = useCallback(() => {
+        if (loading || currentPage >= lastPage) return;
+
+        setLoading(true);
+
+        const url = new URL(fetchUrl, window.location.origin);
+        url.searchParams.set('page', String(currentPage + 1));
+        url.searchParams.set('per_page', String(perPage));
+
+        router.get(
+            url.pathname + url.search,
+            {},
+            {
+                preserveState: true,
+                replace: true,
+                only: ['mutations'],
+                // eslint-disable-next-line @typescript-eslint/no-explicit-any
+                onSuccess: (page: any) => {
+                    const newMutations = (page.props as Record<string, unknown>)
+                        .mutations as PaginatedData<T>;
+
+                    setItems((prev) => [...prev, ...newMutations.data]);
+                    setCurrentPage(newMutations.current_page);
+                    setLastPage(newMutations.last_page);
+                    setLoading(false);
+                },
+                onError: () => {
+                    setLoading(false);
+                },
+            },
+        );
+    }, [fetchUrl, currentPage, lastPage, loading, perPage]);
+
+    useEffect(() => {
+        const sentinel = sentinelRef.current;
+        if (!sentinel) return;
+
+        const observer = new IntersectionObserver(
+            (entries) => {
+                if (entries[0].isIntersecting) {
+                    loadMore();
+                }
+            },
+            { threshold: 0.1 },
+        );
+
+        observer.observe(sentinel);
+
+        return () => observer.disconnect();
+    }, [loadMore]);
+
+    const hasNextPage = currentPage < lastPage;
+
+    return {
+        items,
+        loading,
+        hasNextPage,
+        sentinelRef,
+    };
+}

resources/js/pages/admin/master/product/variant/stock-mutations.tsx

@@ -0,0 +1,230 @@
+import { Button } from '@/components/ui/button';
+import { Card, CardContent } from '@/components/ui/card';
+import { useInfiniteScroll } from '@/hooks/use-infinite-scroll';
+import { stockMutations } from '@/routes/admin/master/products/variants';
+import { Head } from '@inertiajs/react';
+import {
+    ArrowDown,
+    ArrowLeft,
+    ArrowRightLeft,
+    ArrowUp,
+    Loader2,
+    Package,
+    Pencil,
+    ScrollText,
+} from 'lucide-react';
+
+import { index as productIndex } from '@/routes/admin/master/products';
+
+type Mutation = {
+    id: number;
+    type: 'in' | 'out';
+    quantity: number;
+    stock_before: number;
+    stock_after: number;
+    stock_quality: string;
+    description: string | null;
+    created_at: string;
+    user: {
+        id: number;
+        username: string;
+        email: string;
+        full_name?: string;
+    };
+};
+
+type PaginatedMutations = {
+    data: Mutation[];
+    current_page: number;
+    last_page: number;
+    per_page: number;
+    total: number;
+};
+
+type Props = {
+    product: { id: number; name: string };
+    variant: { id: number; name: string };
+    mutations: PaginatedMutations;
+};
+
+function formatNumber(num: number): string {
+    return new Intl.NumberFormat('id-ID').format(num);
+}
+
+function formatDate(dateStr: string): string {
+    return new Intl.DateTimeFormat('id-ID', {
+        day: 'numeric',
+        month: 'long',
+        year: 'numeric',
+        hour: '2-digit',
+        minute: '2-digit',
+    }).format(new Date(dateStr));
+}
+
+function getQualityLabel(quality: string): string {
+    const labels: Record<string, string> = {
+        good: 'Bagus',
+        reject: 'Reject',
+        retail: 'Ecer',
+    };
+    return labels[quality] ?? quality;
+}
+
+function getQualityColor(quality: string): string {
+    const colors: Record<string, string> = {
+        good: 'bg-green-100 text-green-800',
+        reject: 'bg-red-100 text-red-800',
+        retail: 'bg-blue-100 text-blue-800',
+    };
+    return colors[quality] ?? 'bg-gray-100 text-gray-800';
+}
+
+function getTypeLabel(type: string, quantity: number): string {
+    if (type === 'in') {
+        return quantity >= 0 ? 'Penambahan' : 'Pengurangan';
+    }
+    return quantity < 0 ? 'Pengurangan' : 'Penambahan';
+}
+
+function getMutationTitle(description: string | null): string {
+    if (!description) return 'Perubahan Stok';
+    if (description.includes('Transfer stok')) return 'Transfer Stok';
+    if (description.includes('Stok awal')) return 'Stok Awal';
+    if (description.includes('Penyesuaian stok')) return 'Edit Varian';
+    return 'Perubahan Stok';
+}
+
+function getMutationIcon(description: string | null): React.ReactNode {
+    if (description?.includes('Transfer stok')) {
+        return <ArrowRightLeft className="h-4 w-4" />;
+    }
+    if (description?.includes('Stok awal')) {
+        return <Package className="h-4 w-4" />;
+    }
+    if (description?.includes('Penyesuaian stok')) {
+        return <Pencil className="h-4 w-4" />;
+    }
+    return <ScrollText className="h-4 w-4" />;
+}
+
+export default function StockMutationsPage({
+    product,
+    variant,
+    mutations,
+}: Props) {
+    const { items, loading, hasNextPage, sentinelRef } = useInfiniteScroll({
+        initialData: mutations,
+        fetchUrl: stockMutations.url({ product: product.id, variant: variant.id }),
+    });
+
+    return (
+        <>
+            <Head title="Mutasi Stok" />
+
+            <div className="flex h-full flex-1 flex-col gap-6 overflow-x-auto p-4 md:p-6">
+                <div className="flex items-center justify-between">
+                    <div>
+                        <h2 className="text-2xl font-semibold tracking-tight">
+                            Mutasi Stok
+                        </h2>
+                        <p className="mt-1 text-sm text-muted-foreground">
+                            {product.name} — {variant.name}
+                        </p>
+                    </div>
+                    <Button asChild variant="outline">
+                        <a href={productIndex.url()}>
+                            <ArrowLeft className="h-4 w-4" />
+                            Kembali
+                        </a>
+                    </Button>
+                </div>
+
+                <div className="grid gap-4">
+                    {items.length === 0 && !loading ? (
+                        <Card>
+                            <CardContent className="flex flex-col items-center justify-center py-12">
+                                <ScrollText className="h-12 w-12 text-muted-foreground/50" />
+                                <p className="mt-4 text-sm text-muted-foreground">
+                                    Belum ada mutasi stok.
+                                </p>
+                            </CardContent>
+                        </Card>
+                    ) : (
+                        items.map((mutation) => {
+                            const isPositive = mutation.quantity > 0;
+                            const qualityColor = getQualityColor(mutation.stock_quality);
+
+                            return (
+                                <Card key={mutation.id}>
+                                    <CardContent className="p-4">
+                                        <div className="flex items-start gap-4">
+                                            <div className={`flex h-10 w-10 shrink-0 items-center justify-center rounded-full ${isPositive ? 'bg-green-100 text-green-600' : 'bg-red-100 text-red-600'}`}>
+                                                {isPositive ? (
+                                                    <ArrowUp className="h-5 w-5" />
+                                                ) : (
+                                                    <ArrowDown className="h-5 w-5" />
+                                                )}
+                                            </div>
+
+                                            <div className="min-w-0 flex-1">
+                                                <div className="flex flex-wrap items-center gap-2">
+                                                    <span className="font-medium">
+                                                        {getMutationTitle(mutation.description)}
+                                                    </span>
+                                                    <span className={`inline-flex items-center rounded-md px-2 py-0.5 text-xs font-medium ${qualityColor}`}>
+                                                        {getQualityLabel(mutation.stock_quality)}
+                                                    </span>
+                                                </div>
+
+                                                <div className="mt-1 flex flex-wrap items-center gap-x-4 gap-y-1 text-sm text-muted-foreground">
+                                                    <span>
+                                                        {formatDate(mutation.created_at)}
+                                                    </span>
+                                                    <span>
+                                                        {mutation.user?.full_name ?? mutation.user?.username}
+                                                    </span>
+                                                </div>
+
+                                                <div className="mt-2 flex flex-wrap items-center gap-x-4 gap-y-1 text-sm">
+                                                    <span className={isPositive ? 'font-medium text-green-600' : 'font-medium text-red-600'}>
+                                                        {isPositive ? '+' : ''}{formatNumber(mutation.quantity)}
+                                                    </span>
+                                                    <span className="text-muted-foreground">
+                                                        {formatNumber(mutation.stock_before)} → {formatNumber(mutation.stock_after)}
+                                                    </span>
+                                                </div>
+
+                                                {mutation.description && (
+                                                    <p className="mt-1 text-xs text-muted-foreground">
+                                                        {mutation.description}
+                                                    </p>
+                                                )}
+                                            </div>
+                                        </div>
+                                    </CardContent>
+                                </Card>
+                            );
+                        })
+                    )}
+
+                    {hasNextPage && (
+                        <div ref={sentinelRef} className="flex items-center justify-center py-4">
+                            {loading && (
+                                <div className="flex items-center gap-2 text-sm text-muted-foreground">
+                                    <Loader2 className="h-4 w-4 animate-spin" />
+                                    Memuat data...
+                                </div>
+                            )}
+                        </div>
+                    )}
+
+                    {!hasNextPage && items.length > 0 && (
+                        <p className="py-4 text-center text-sm text-muted-foreground">
+                            Semua data sudah dimuat.
+                        </p>
+                    )}
+                </div>
+            </div>
+        </>
+    );
+}

resources/js/pages/admin/master/product/variant/sub-row.tsx

@@ -1,4 +1,4 @@
-import { ArrowRightLeft, Pencil, Trash2 } from 'lucide-react';
+import { ArrowRightLeft, Pencil, ScrollText, Trash2 } from 'lucide-react';
 import { useState } from 'react';
 import { ImagePreviewModal } from '@/components/image-preview-modal';
 import { Button } from '@/components/ui/button';
@@ -17,6 +17,7 @@ import {
     TooltipTrigger,
 } from '@/components/ui/tooltip';
 import type { Product, ProductVariant } from '../columns';
+import { stockMutations } from '@/routes/admin/master/products/variants';
 import { TransferStockDialog } from './transfer-stock-dialog';
 
 function formatCurrency(amount: number): string {
@@ -181,6 +182,25 @@ export function VariantSubRow({
                                                     Transfer Stok
                                                 </TooltipContent>
                                             </Tooltip>
+                                            <Tooltip>
+                                                <TooltipTrigger asChild>
+                                                    <Button
+                                                        variant="ghost"
+                                                        size="icon"
+                                                        onClick={() => {
+                                                            window.location.href = stockMutations.url({
+                                                                product: product.id,
+                                                                variant: variant.id,
+                                                            });
+                                                        }}
+                                                    >
+                                                        <ScrollText className="h-4 w-4" />
+                                                    </Button>
+                                                </TooltipTrigger>
+                                                <TooltipContent side="top">
+                                                    Mutasi Stok
+                                                </TooltipContent>
+                                            </Tooltip>
                                             <Tooltip>
                                                 <TooltipTrigger asChild>
                                                     <Button

routes/web.php

@@ -14,6 +14,7 @@
 use App\Http\Controllers\Admin\Master\CustomerController;
 use App\Http\Controllers\Admin\Master\Product\ProductController;
 use App\Http\Controllers\Admin\Master\Product\ProductVariantController;
+use App\Http\Controllers\Admin\Master\Product\StockMutationController;
 use App\Http\Controllers\Admin\Master\SupplierController;
 use App\Http\Controllers\Admin\RoleController;
 use Illuminate\Support\Facades\Route;
@@ -38,6 +39,7 @@
         Route::get('products/{product}/variants/{variant}/edit', [ProductVariantController::class, 'edit'])->name('products.variants.edit');
         Route::put('products/{product}/variants/{variant}', [ProductVariantController::class, 'update'])->name('products.variants.update');
         Route::post('products/{product}/variants/{variant}/transfer-stock', [ProductVariantController::class, 'transferStock'])->name('products.variants.transfer-stock');
+        Route::get('products/{product}/variants/{variant}/stock-mutations', [StockMutationController::class, 'index'])->name('products.variants.stock-mutations');
         Route::resource('suppliers', SupplierController::class)->except(['show', 'create', 'edit']);
         Route::resource('customers', CustomerController::class)->except(['show', 'create', 'edit']);
     });

tests/Feature/Admin/Master/ProductTest.php

@@ -2526,3 +2526,281 @@ function allPriceTypes(): array
 
     $response->assertRedirect(route('admin.master.products.index'));
 });
+
+/*
+|--------------------------------------------------------------------------
+| STOCK MUTATION AUDIT TRAIL
+|--------------------------------------------------------------------------
+*/
+
+test('creating product with stock creates initial stock mutations', function () {
+    $user = User::factory()->create();
+    $this->actingAs($user);
+
+    $this->post(route('admin.master.products.store'), makeValidProductPayload([
+        'variants' => [[
+            'name' => 'Varian Audit',
+            'stock' => 50,
+            'reject_stock' => 5,
+            'retail_stock' => 10,
+            'photo_keys' => ['product-variant/audit.jpg'],
+            'prices' => allPriceTypes(),
+        ]],
+    ]));
+
+    $variant = ProductVariant::where('name', 'Varian Audit')->first();
+
+    $this->assertDatabaseCount('stock_mutations', 3);
+
+    $goodMutation = StockMutation::where('stockable_id', $variant->id)->where('stock_quality', 'good')->first();
+    expect($goodMutation)->not->toBeNull();
+    expect($goodMutation->type)->toBe('in');
+    expect((float) $goodMutation->quantity)->toBe(50.0);
+    expect((float) $goodMutation->stock_before)->toBe(0.0);
+    expect((float) $goodMutation->stock_after)->toBe(50.0);
+    expect($goodMutation->description)->toBe('Stok awal saat pembuatan varian');
+
+    $rejectMutation = StockMutation::where('stockable_id', $variant->id)->where('stock_quality', 'reject')->first();
+    expect((float) $rejectMutation->quantity)->toBe(5.0);
+
+    $retailMutation = StockMutation::where('stockable_id', $variant->id)->where('stock_quality', 'retail')->first();
+    expect((float) $retailMutation->quantity)->toBe(10.0);
+});
+
+test('creating product with zero stock creates no mutations', function () {
+    $user = User::factory()->create();
+    $this->actingAs($user);
+
+    $this->post(route('admin.master.products.store'), makeValidProductPayload([
+        'variants' => [[
+            'name' => 'Varian Kosong',
+            'stock' => 0,
+            'reject_stock' => 0,
+            'retail_stock' => 0,
+            'photo_keys' => ['product-variant/empty.jpg'],
+            'prices' => allPriceTypes(),
+        ]],
+    ]));
+
+    $this->assertDatabaseCount('stock_mutations', 0);
+});
+
+test('updating variant stock creates adjustment mutations', function () {
+    $user = User::factory()->create();
+    $this->actingAs($user);
+
+    $product = Product::factory()->create();
+    $category = Category::factory()->create();
+    DB::table('product_categories')->insert([
+        'product_id' => $product->id,
+        'category_id' => $category->id,
+    ]);
+    $variant = ProductVariant::factory()->for($product)->create([
+        'name' => 'Original',
+        'stock' => 100,
+        'reject_stock' => 10,
+        'retail_stock' => 20,
+    ]);
+    foreach (allPriceTypes() as $price) {
+        ProductPrice::factory()->create(['variant_id' => $variant->id, 'type' => $price['type'], 'price' => $price['price']]);
+    }
+
+    $this->put(route('admin.master.products.update', $product), makeValidProductPayload([
+        'name' => $product->name,
+        'category_ids' => [$category->id],
+        'variants' => [[
+            'id' => $variant->id,
+            'name' => 'Original',
+            'stock' => 120,
+            'reject_stock' => 10,
+            'retail_stock' => 25,
+            'photo_keys' => ['product-variant/updated.jpg'],
+            'prices' => allPriceTypes(),
+        ]],
+    ]));
+
+    $goodMutation = StockMutation::where('stockable_id', $variant->id)->where('stock_quality', 'good')->first();
+    expect($goodMutation)->not->toBeNull();
+    expect($goodMutation->type)->toBe('in');
+    expect((float) $goodMutation->quantity)->toBe(20.0);
+    expect((float) $goodMutation->stock_before)->toBe(100.0);
+    expect((float) $goodMutation->stock_after)->toBe(120.0);
+
+    $retailMutation = StockMutation::where('stockable_id', $variant->id)->where('stock_quality', 'retail')->first();
+    expect((float) $retailMutation->quantity)->toBe(5.0);
+});
+
+test('updating variant via single edit creates adjustment mutations', function () {
+    $user = User::factory()->create();
+    $this->actingAs($user);
+
+    $product = Product::factory()->create();
+    $variant = ProductVariant::factory()->for($product)->create([
+        'name' => 'Single Edit',
+        'stock' => 80,
+        'reject_stock' => 5,
+        'retail_stock' => 15,
+    ]);
+
+    $this->put(route('admin.master.products.variants.update', [$product, $variant]), [
+        'name' => 'Single Edit',
+        'stock' => 70,
+        'reject_stock' => 8,
+        'retail_stock' => 15,
+        'photo_keys' => ['product-variant/single-edit.jpg'],
+        'prices' => allPriceTypes(),
+    ]);
+
+    $goodMutation = StockMutation::where('stockable_id', $variant->id)->where('stock_quality', 'good')->first();
+    expect($goodMutation)->not->toBeNull();
+    expect($goodMutation->type)->toBe('out');
+    expect((float) $goodMutation->quantity)->toBe(-10.0);
+
+    $rejectMutation = StockMutation::where('stockable_id', $variant->id)->where('stock_quality', 'reject')->first();
+    expect((float) $rejectMutation->quantity)->toBe(3.0);
+
+    $retailMutation = StockMutation::where('stockable_id', $variant->id)->where('stock_quality', 'retail')->first();
+    expect($retailMutation)->toBeNull();
+});
+
+test('no mutation created when stock values unchanged', function () {
+    $user = User::factory()->create();
+    $this->actingAs($user);
+
+    $product = Product::factory()->create();
+    $category = Category::factory()->create();
+    DB::table('product_categories')->insert([
+        'product_id' => $product->id,
+        'category_id' => $category->id,
+    ]);
+    $variant = ProductVariant::factory()->for($product)->create([
+        'name' => 'Unchanged',
+        'stock' => 50,
+        'reject_stock' => 10,
+        'retail_stock' => 20,
+    ]);
+    foreach (allPriceTypes() as $price) {
+        ProductPrice::factory()->create(['variant_id' => $variant->id, 'type' => $price['type'], 'price' => $price['price']]);
+    }
+
+    $this->put(route('admin.master.products.update', $product), makeValidProductPayload([
+        'name' => 'Updated Name Only',
+        'category_ids' => [$category->id],
+        'variants' => [[
+            'id' => $variant->id,
+            'name' => 'Unchanged',
+            'stock' => 50,
+            'reject_stock' => 10,
+            'retail_stock' => 20,
+            'photo_keys' => ['product-variant/unchanged.jpg'],
+            'prices' => allPriceTypes(),
+        ]],
+    ]));
+
+    $this->assertDatabaseCount('stock_mutations', 0);
+});
+
+test('stock mutations record user who performed the action', function () {
+    $user = User::factory()->create();
+    $this->actingAs($user);
+
+    $product = Product::factory()->create();
+    $variant = ProductVariant::factory()->for($product)->create(['stock' => 100]);
+
+    $this->post(route('admin.master.products.variants.transfer-stock', [$product, $variant]), [
+        'quantity' => 10,
+    ]);
+
+    $mutation = StockMutation::where('stockable_id', $variant->id)->first();
+    expect($mutation->user_id)->toBe($user->id);
+});
+
+/*
+|--------------------------------------------------------------------------
+| STOCK MUTATIONS PAGE
+|--------------------------------------------------------------------------
+*/
+
+test('guest cannot access stock mutations page', function () {
+    $product = Product::factory()->create();
+    $variant = ProductVariant::factory()->for($product)->create();
+
+    $response = $this->get(route('admin.master.products.variants.stock-mutations', [$product, $variant]));
+    $response->assertRedirect(route('login'));
+});
+
+test('authenticated user can access stock mutations page', function () {
+    $user = User::factory()->create();
+    $this->actingAs($user);
+
+    $product = Product::factory()->create();
+    $variant = ProductVariant::factory()->for($product)->create();
+
+    $response = $this->get(route('admin.master.products.variants.stock-mutations', [$product, $variant]));
+    $response->assertOk();
+    $response->assertInertia(fn (Assert $page) => $page
+        ->component('admin/master/product/variant/stock-mutations')
+        ->has('mutations.data', 0)
+        ->where('product.id', $product->id)
+        ->where('variant.id', $variant->id)
+    );
+});
+
+test('stock mutations page displays mutations for specific variant', function () {
+    $user = User::factory()->create();
+    $this->actingAs($user);
+
+    $product = Product::factory()->create();
+    $variant = ProductVariant::factory()->for($product)->create(['stock' => 100]);
+
+    $this->post(route('admin.master.products.variants.transfer-stock', [$product, $variant]), [
+        'quantity' => 10,
+    ]);
+
+    $response = $this->get(route('admin.master.products.variants.stock-mutations', [$product, $variant]));
+    $response->assertOk();
+    $response->assertInertia(fn (Assert $page) => $page
+        ->component('admin/master/product/variant/stock-mutations')
+        ->has('mutations.data', 2)
+    );
+});
+
+test('stock mutations page does not show mutations from other variants', function () {
+    $user = User::factory()->create();
+    $this->actingAs($user);
+
+    $product = Product::factory()->create();
+    $variant1 = ProductVariant::factory()->for($product)->create(['stock' => 100]);
+    $variant2 = ProductVariant::factory()->for($product)->create(['stock' => 50]);
+
+    $this->post(route('admin.master.products.variants.transfer-stock', [$product, $variant1]), [
+        'quantity' => 10,
+    ]);
+
+    $response = $this->get(route('admin.master.products.variants.stock-mutations', [$product, $variant1]));
+    $response->assertInertia(fn (Assert $page) => $page
+        ->component('admin/master/product/variant/stock-mutations')
+        ->has('mutations.data', 2)
+    );
+
+    $response = $this->get(route('admin.master.products.variants.stock-mutations', [$product, $variant2]));
+    $response->assertInertia(fn (Assert $page) => $page
+        ->component('admin/master/product/variant/stock-mutations')
+        ->has('mutations.data', 0)
+    );
+});
+
+test('stock mutations page shows correct product and variant info', function () {
+    $user = User::factory()->create();
+    $this->actingAs($user);
+
+    $product = Product::factory()->create(['name' => 'Produk Test']);
+    $variant = ProductVariant::factory()->for($product)->create(['name' => 'Varian Test']);
+
+    $response = $this->get(route('admin.master.products.variants.stock-mutations', [$product, $variant]));
+    $response->assertOk();
+    $response->assertInertia(fn (Assert $page) => $page
+        ->where('product.name', 'Produk Test')
+        ->where('variant.name', 'Varian Test')
+    );
+});