diff --git a/database/migrations/tenant/2026_01_20_085700_add_performance_indexes_to_activity_log.php b/database/migrations/tenant/2026_01_20_085700_add_performance_indexes_to_activity_log.php
new file mode 100644
index 0000000..7d40d21
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+++ b/database/migrations/tenant/2026_01_20_085700_add_performance_indexes_to_activity_log.php
@@ -0,0 +1,45 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::connection(config('activitylog.database_connection'))->table(config('activitylog.table_name'), function (Blueprint $table) {
+            // 單欄索引：事件類型（高頻過濾條件）
+            $table->index('event', 'idx_event');
+            
+            // 單欄索引：批次 UUID（未來批次操作查詢）
+            $table->index('batch_uuid', 'idx_batch_uuid');
+            
+            // 複合索引 1：時間 + 事件類型（最常見的組合查詢）
+            $table->index(['created_at', 'event'], 'idx_created_event');
+            
+            // 複合索引 2：主體類型 + 主體 ID + 時間（查詢特定資源的操作歷史）
+            $table->index(['subject_type', 'subject_id', 'created_at'], 'idx_subject_created');
+            
+            // 複合索引 3：操作者 + 時間（查詢特定使用者的操作紀錄）
+            $table->index(['causer_id', 'created_at'], 'idx_causer_created');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::connection(config('activitylog.database_connection'))->table(config('activitylog.table_name'), function (Blueprint $table) {
+            $table->dropIndex('idx_event');
+            $table->dropIndex('idx_batch_uuid');
+            $table->dropIndex('idx_created_event');
+            $table->dropIndex('idx_subject_created');
+            $table->dropIndex('idx_causer_created');
+        });
+    }
+};