diff --git a/database/migrations/2025_12_14_012415_drop_legacy_product_material_id_columns.php b/database/migrations/2025_12_14_012415_drop_legacy_product_material_id_columns.php
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+++ b/database/migrations/2025_12_14_012415_drop_legacy_product_material_id_columns.php
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+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Schema;
+
+/**
+ * Phase 5.5: 레거시 product_id/material_id 컬럼 삭제
+ *
+ * 전제조건:
+ * - items 테이블로 데이터 마이그레이션 완료
+ * - item_id 컬럼에 데이터 매핑 완료
+ * - products/materials 테이블 삭제됨
+ */
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        // 1. orders.product_id 삭제
+        if (Schema::hasTable('orders') && Schema::hasColumn('orders', 'product_id')) {
+            Schema::table('orders', function (Blueprint $table) {
+                $table->dropColumn('product_id');
+            });
+        }
+
+        // 2. order_items.product_id 삭제
+        if (Schema::hasTable('order_items') && Schema::hasColumn('order_items', 'product_id')) {
+            Schema::table('order_items', function (Blueprint $table) {
+                $table->dropColumn('product_id');
+            });
+        }
+
+        // 3. quotes.product_id 삭제
+        if (Schema::hasTable('quotes') && Schema::hasColumn('quotes', 'product_id')) {
+            Schema::table('quotes', function (Blueprint $table) {
+                $table->dropColumn('product_id');
+            });
+        }
+
+        // 4. material_receipts.material_id 삭제
+        if (Schema::hasTable('material_receipts') && Schema::hasColumn('material_receipts', 'material_id')) {
+            Schema::table('material_receipts', function (Blueprint $table) {
+                $table->dropColumn('material_id');
+            });
+        }
+
+        // 5. lots.material_id 삭제
+        if (Schema::hasTable('lots') && Schema::hasColumn('lots', 'material_id')) {
+            Schema::table('lots', function (Blueprint $table) {
+                $table->dropColumn('material_id');
+            });
+        }
+
+        DB::statement("SELECT 'Dropped legacy product_id/material_id columns' AS result");
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * 주의: 컬럼 복원만 수행, 데이터는 item_id_mappings로 복원 필요
+     */
+    public function down(): void
+    {
+        // 1. orders.product_id 복원
+        if (Schema::hasTable('orders') && ! Schema::hasColumn('orders', 'product_id')) {
+            Schema::table('orders', function (Blueprint $table) {
+                $table->unsignedBigInteger('product_id')->nullable()->after('category_code')
+                    ->comment('(deprecated) 기존 products 참조');
+            });
+        }
+
+        // 2. order_items.product_id 복원
+        if (Schema::hasTable('order_items') && ! Schema::hasColumn('order_items', 'product_id')) {
+            Schema::table('order_items', function (Blueprint $table) {
+                $table->unsignedBigInteger('product_id')->nullable()->after('serial_no')
+                    ->comment('(deprecated) 기존 products 참조');
+            });
+        }
+
+        // 3. quotes.product_id 복원
+        if (Schema::hasTable('quotes') && ! Schema::hasColumn('quotes', 'product_id')) {
+            Schema::table('quotes', function (Blueprint $table) {
+                $table->unsignedBigInteger('product_id')->nullable()->after('product_category')
+                    ->comment('(deprecated) 기존 products 참조');
+            });
+        }
+
+        // 4. material_receipts.material_id 복원
+        if (Schema::hasTable('material_receipts') && ! Schema::hasColumn('material_receipts', 'material_id')) {
+            Schema::table('material_receipts', function (Blueprint $table) {
+                $table->unsignedBigInteger('material_id')->nullable()->first()
+                    ->comment('(deprecated) 기존 materials 참조');
+            });
+        }
+
+        // 5. lots.material_id 복원
+        if (Schema::hasTable('lots') && ! Schema::hasColumn('lots', 'material_id')) {
+            Schema::table('lots', function (Blueprint $table) {
+                $table->unsignedBigInteger('material_id')->nullable()->after('id')
+                    ->comment('(deprecated) 기존 materials 참조');
+            });
+        }
+
+        // 데이터 복원 안내
+        DB::statement("SELECT 'Columns restored. Use item_id_mappings to restore data if needed.' AS warning");
+    }
+};