diff --git a/database/migrations/2026_03_10_224806_add_tenant_id_to_document_detail_tables.php b/database/migrations/2026_03_10_224806_add_tenant_id_to_document_detail_tables.php
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+++ b/database/migrations/2026_03_10_224806_add_tenant_id_to_document_detail_tables.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;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        $tables = ['document_data', 'document_approvals', 'document_attachments'];
+
+        foreach ($tables as $table) {
+            Schema::table($table, function (Blueprint $table) {
+                $table->unsignedBigInteger('tenant_id')->nullable()->after('id')->comment('테넌트 ID');
+                $table->index('tenant_id');
+            });
+
+            // 부모 테이블(documents)에서 tenant_id 채우기
+            DB::statement("
+                UPDATE {$table} t
+                JOIN documents d ON t.document_id = d.id
+                SET t.tenant_id = d.tenant_id
+            ");
+        }
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        $tables = ['document_data', 'document_approvals', 'document_attachments'];
+
+        foreach ($tables as $table) {
+            Schema::table($table, function (Blueprint $table) {
+                $table->dropIndex(['tenant_id']);
+                $table->dropColumn('tenant_id');
+            });
+        }
+    }
+};
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