diff --git a/.env.example b/.env.example
index 82ddd36..a3239c3 100644
--- a/.env.example
+++ b/.env.example
@@ -37,13 +37,13 @@ BROADCAST_CONNECTION=log
 FILESYSTEM_DISK=local
 QUEUE_CONNECTION=database
 
-CACHE_STORE=database
+CACHE_STORE=redis
 CACHE_PREFIX=
 
 MEMCACHED_HOST=127.0.0.1
 
-REDIS_CLIENT=phpredis
-REDIS_HOST=127.0.0.1
+REDIS_CLIENT=predis
+REDIS_HOST=redis
 REDIS_PASSWORD=null
 REDIS_PORT=6379
 
diff --git a/.gitignore b/.gitignore
index 8808326..33f4b39 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 /.phpunit.cache
+docker-compose.override.yml
 /node_modules
 /public/build
 /public/hot
diff --git a/app/Http/Controllers/API/AdminReviewController.php b/app/Http/Controllers/API/AdminReviewController.php
index c963aaa..b781b89 100644
--- a/app/Http/Controllers/API/AdminReviewController.php
+++ b/app/Http/Controllers/API/AdminReviewController.php
@@ -10,23 +10,34 @@ use Illuminate\Support\Facades\DB;
 
 class AdminReviewController extends Controller
 {
-    public function index()
+    public function index(Request $request)
     {
-        $reviews = Review::with(['divingOffer', 'member'])
+        $perPage   = min((int) $request->query('per_page', 20), 100);
+        $paginator = Review::with(['divingOffer', 'member'])
             ->orderByDesc('created_at')
-            ->get()
-            ->map(fn($r) => [
-                'id'          => $r->id,
-                'offer_title' => $r->divingOffer?->title,
-                'member_email'=> $r->member?->email,
-                'rating'      => $r->rating,
-                'comment'     => mb_strimwidth($r->comment, 0, 50, '...'),
-                'is_edited'   => $r->is_edited,
-                'helpful_count'=> $r->helpful_count,
-                'created_at'  => $r->created_at?->toISOString(),
-            ]);
+            ->paginate($perPage);
 
-        return response()->json(['status' => true, 'data' => $reviews]);
+        $reviews = $paginator->getCollection()->map(fn($r) => [
+            'id'           => $r->id,
+            'offer_title'  => $r->divingOffer?->title,
+            'member_email' => $r->member?->email,
+            'rating'       => $r->rating,
+            'comment'      => mb_strimwidth($r->comment, 0, 50, '...'),
+            'is_edited'    => $r->is_edited,
+            'helpful_count'=> $r->helpful_count,
+            'created_at'   => $r->created_at?->toISOString(),
+        ]);
+
+        return response()->json([
+            'status' => true,
+            'data'   => $reviews,
+            'meta'   => [
+                'current_page' => $paginator->currentPage(),
+                'last_page'    => $paginator->lastPage(),
+                'per_page'     => $paginator->perPage(),
+                'total'        => $paginator->total(),
+            ],
+        ]);
     }
 
     public function destroy(int $id)
diff --git a/app/Http/Controllers/API/AdminStatsController.php b/app/Http/Controllers/API/AdminStatsController.php
index 10ea996..70259bb 100644
--- a/app/Http/Controllers/API/AdminStatsController.php
+++ b/app/Http/Controllers/API/AdminStatsController.php
@@ -5,6 +5,7 @@ namespace App\Http\Controllers\API;
 use App\Http\Controllers\Controller;
 use App\Models\DivingOffer;
 use App\Models\User;
+use Illuminate\Support\Facades\Cache;
 
 class AdminStatsController extends Controller
 {
@@ -14,13 +15,12 @@ class AdminStatsController extends Controller
             return response()->json(['status' => false, 'message' => '無權限存取'], 403);
         }
 
-        return response()->json([
-            'status' => true,
-            'data'   => [
-                'total_members'   => User::where('role', 'member')->count(),
-                'total_providers' => User::where('role', 'provider')->count(),
-                'total_offers'    => DivingOffer::count(),
-            ],
+        $stats = Cache::remember('admin_stats', 300, fn() => [
+            'total_members'   => User::where('role', 'member')->count(),
+            'total_providers' => User::where('role', 'provider')->count(),
+            'total_offers'    => DivingOffer::count(),
         ]);
+
+        return response()->json(['status' => true, 'data' => $stats]);
     }
 }
diff --git a/app/Http/Controllers/API/DivingOfferController.php b/app/Http/Controllers/API/DivingOfferController.php
index 3a8b574..96d6e33 100644
--- a/app/Http/Controllers/API/DivingOfferController.php
+++ b/app/Http/Controllers/API/DivingOfferController.php
@@ -5,44 +5,51 @@ namespace App\Http\Controllers\API;
 use App\Http\Controllers\Controller;
 use App\Models\DivingOffer;
 use Illuminate\Http\Request;
+use Illuminate\Support\Facades\Cache;
 
 class DivingOfferController extends Controller
 {
     public function index(Request $request)
     {
-        $perPage = min((int) $request->query('per_page', 12), 50);
+        $perPage  = min((int) $request->query('per_page', 12), 50);
+        $cacheKey = 'diving_offers_' . md5(serialize($request->all()));
 
-        $query = DivingOffer::query();
+        $result = Cache::tags(['diving_offers'])->remember($cacheKey, 180, function () use ($request, $perPage) {
+            $query = DivingOffer::query();
 
-        if ($q = $request->query('q')) {
-            $query->where(function ($sub) use ($q) {
-                $sub->where('title', 'like', "%{$q}%")
-                    ->orWhere('location', 'like', "%{$q}%")
-                    ->orWhere('spot', 'like', "%{$q}%");
-            });
-        }
+            if ($q = $request->query('q')) {
+                $query->where(function ($sub) use ($q) {
+                    $sub->where('title', 'like', "%{$q}%")
+                        ->orWhere('location', 'like', "%{$q}%")
+                        ->orWhere('spot', 'like', "%{$q}%");
+                });
+            }
 
-        if ($region = $request->query('region')) {
-            $query->where('region', $region);
-        }
+            if ($region = $request->query('region')) {
+                $query->where('region', $region);
+            }
 
-        if ($tag = $request->query('tag')) {
-            $query->where('tag', 'like', "%{$tag}%");
-        }
+            if ($tag = $request->query('tag')) {
+                $query->where('tag', 'like', "%{$tag}%");
+            }
 
-        $paginated = $query->paginate($perPage);
+            $paginated = $query->paginate($perPage);
 
-        $items = collect($paginated->items())->map(fn($o) => $this->formatOffer($o, false));
+            return [
+                'items' => collect($paginated->items())->map(fn($o) => $this->formatOffer($o, false))->values(),
+                'meta'  => [
+                    'total'        => $paginated->total(),
+                    'per_page'     => $paginated->perPage(),
+                    'current_page' => $paginated->currentPage(),
+                    'last_page'    => $paginated->lastPage(),
+                ],
+            ];
+        });
 
         return response()->json([
             'status' => true,
-            'data'   => $items,
-            'meta'   => [
-                'total'        => $paginated->total(),
-                'per_page'     => $paginated->perPage(),
-                'current_page' => $paginated->currentPage(),
-                'last_page'    => $paginated->lastPage(),
-            ],
+            'data'   => $result['items'],
+            'meta'   => $result['meta'],
         ]);
     }
 
diff --git a/app/Http/Controllers/API/ProviderOfferController.php b/app/Http/Controllers/API/ProviderOfferController.php
index b086349..a7642fa 100644
--- a/app/Http/Controllers/API/ProviderOfferController.php
+++ b/app/Http/Controllers/API/ProviderOfferController.php
@@ -5,6 +5,7 @@ namespace App\Http\Controllers\API;
 use App\Http\Controllers\Controller;
 use App\Models\DivingOffer;
 use Illuminate\Http\Request;
+use Illuminate\Support\Facades\Cache;
 
 class ProviderOfferController extends Controller
 {
@@ -60,6 +61,8 @@ class ProviderOfferController extends Controller
 
         $offer = DivingOffer::create($validated);
 
+        Cache::tags(['diving_offers'])->flush();
+
         return response()->json(['status' => true, 'data' => $offer], 201);
     }
 
@@ -89,6 +92,8 @@ class ProviderOfferController extends Controller
 
         $offer->fill($validated)->save();
 
+        Cache::tags(['diving_offers'])->flush();
+
         return response()->json(['status' => true, 'data' => $offer]);
     }
 
@@ -106,6 +111,8 @@ class ProviderOfferController extends Controller
 
         $offer->delete();
 
+        Cache::tags(['diving_offers'])->flush();
+
         return response()->json(['status' => true, 'message' => '課程已刪除']);
     }
 }
diff --git a/app/Http/Controllers/API/ReviewController.php b/app/Http/Controllers/API/ReviewController.php
index e34ffc5..9c1da16 100644
--- a/app/Http/Controllers/API/ReviewController.php
+++ b/app/Http/Controllers/API/ReviewController.php
@@ -11,6 +11,7 @@ use App\Models\ReviewEdit;
 use App\Models\ReviewVote;
 use App\Notifications\ReviewReceivedNotification;
 use Illuminate\Http\Request;
+use Illuminate\Support\Facades\Cache;
 use Illuminate\Support\Facades\DB;
 use Illuminate\Support\Facades\Log;
 
@@ -20,11 +21,12 @@ class ReviewController extends Controller
 
     public function publicList(Request $request, int $offerId)
     {
-        $offer = DivingOffer::findOrFail($offerId);
-        $user  = $request->user();
+        $offer   = DivingOffer::findOrFail($offerId);
+        $user    = $request->user();
+        $perPage = min((int) $request->query('per_page', 20), 50);
+        $sort    = $request->query('sort', 'helpful');
 
-        $sort = $request->query('sort', 'helpful');
-        $query = Review::where('diving_offer_id', $offer->id);
+        $query = Review::with('votes')->where('diving_offer_id', $offer->id);
 
         match ($sort) {
             'rating'  => $query->orderByDesc('rating')->orderByDesc('created_at'),
@@ -32,27 +34,25 @@ class ReviewController extends Controller
             default   => $query->orderByDesc('helpful_count')->orderByDesc('created_at'),
         };
 
-        $reviews = $query->get();
+        $paginator = $query->paginate($perPage);
+        $reviews   = $paginator->getCollection();
 
-        // 批次查詢 has_voted
-        $votedIds = $user
-            ? ReviewVote::where('member_id', $user->id)
-                ->whereIn('review_id', $reviews->pluck('id'))
-                ->pluck('review_id')
-                ->flip()
-            : collect();
+        $memberId = $user?->id;
 
-        // summary
-        $distRaw = Review::where('diving_offer_id', $offer->id)
-            ->selectRaw('rating, COUNT(*) as cnt')
-            ->groupBy('rating')
-            ->pluck('cnt', 'rating');
-        $distribution = collect([1 => 0, 2 => 0, 3 => 0, 4 => 0, 5 => 0])->merge($distRaw);
+        $distribution = Cache::remember("offer_review_distribution_{$offerId}", 600, function () use ($offerId) {
+            $distRaw = Review::where('diving_offer_id', $offerId)
+                ->selectRaw('rating, COUNT(*) as cnt')
+                ->groupBy('rating')
+                ->pluck('cnt', 'rating');
+            return collect([1 => 0, 2 => 0, 3 => 0, 4 => 0, 5 => 0])->merge($distRaw);
+        });
 
-        $total   = $reviews->count();
-        $average = $total > 0 ? round($reviews->avg('rating'), 1) : 0;
+        $total   = $paginator->total();
+        $average = $total > 0 ? round(
+            Review::where('diving_offer_id', $offerId)->avg('rating'), 1
+        ) : 0;
 
-        $formatted = $reviews->map(function ($r) use ($user, $votedIds) {
+        $formatted = $reviews->map(function ($r) use ($user, $memberId) {
             $item = [
                 'id'            => $r->id,
                 'reviewer_name' => '匿名潛水者',
@@ -61,10 +61,12 @@ class ReviewController extends Controller
                 'helpful_count' => $r->helpful_count,
                 'is_edited'     => $r->is_edited,
                 'created_at'    => $r->created_at?->toISOString(),
-                'has_voted'     => $votedIds->has($r->id),
+                'has_voted'     => $memberId
+                    ? $r->votes->contains('member_id', $memberId)
+                    : false,
             ];
             if ($user) {
-                $item['is_mine'] = $r->member_id === $user->id;
+                $item['is_mine'] = $r->member_id === $memberId;
             }
             return $item;
         });
@@ -78,6 +80,12 @@ class ReviewController extends Controller
                     'distribution' => $distribution,
                 ],
                 'reviews' => $formatted,
+                'meta'    => [
+                    'current_page' => $paginator->currentPage(),
+                    'last_page'    => $paginator->lastPage(),
+                    'per_page'     => $paginator->perPage(),
+                    'total'        => $paginator->total(),
+                ],
             ],
         ]);
     }
@@ -121,6 +129,8 @@ class ReviewController extends Controller
             return $review;
         });
 
+        Cache::forget("offer_review_distribution_{$offerId}");
+
         try {
             $offer    = DivingOffer::with('provider')->findOrFail($offerId);
             $provider = $offer->provider;
@@ -146,6 +156,8 @@ class ReviewController extends Controller
             'comment' => 'sometimes|string|min:1',
         ]);
 
+        $offerId = $review->diving_offer_id;
+
         DB::transaction(function () use ($review, $data) {
             ReviewEdit::updateOrCreate(
                 ['review_id' => $review->id],
@@ -155,6 +167,8 @@ class ReviewController extends Controller
             $this->recalculateOfferRating($review->diving_offer_id);
         });
 
+        Cache::forget("offer_review_distribution_{$offerId}");
+
         return response()->json(['status' => true, 'message' => '評價已更新', 'data' => $this->formatReview($review->fresh())]);
     }
 
@@ -171,6 +185,8 @@ class ReviewController extends Controller
             $this->recalculateOfferRating($offerId);
         });
 
+        Cache::forget("offer_review_distribution_{$offerId}");
+
         return response()->json(['status' => true, 'message' => '評價已刪除']);
     }
 
diff --git a/composer.json b/composer.json
index 7155ab3..7b0fe8c 100644
--- a/composer.json
+++ b/composer.json
@@ -10,7 +10,8 @@
         "laravel/framework": "^11.0",
         "laravel/sanctum": "^4.1",
         "laravel/socialite": "^5.20",
-        "laravel/tinker": "^2.9"
+        "laravel/tinker": "^2.9",
+        "predis/predis": "^3.4"
     },
     "require-dev": {
         "fakerphp/faker": "^1.23",
diff --git a/composer.lock b/composer.lock
index 24f57f9..cbc94d4 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "cd7975455a8ac2a316ac819eaed700e8",
+    "content-hash": "c7d653b10f8ee748e5662242029651ce",
     "packages": [
         {
             "name": "brick/math",
@@ -3242,6 +3242,69 @@
             ],
             "time": "2024-12-14T21:12:59+00:00"
         },
+        {
+            "name": "predis/predis",
+            "version": "v3.4.2",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/predis/predis.git",
+                "reference": "2033429520d8997a7815a2485f56abe6d2d0e075"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/predis/predis/zipball/2033429520d8997a7815a2485f56abe6d2d0e075",
+                "reference": "2033429520d8997a7815a2485f56abe6d2d0e075",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^7.2 || ^8.0",
+                "psr/http-message": "^1.0|^2.0"
+            },
+            "require-dev": {
+                "friendsofphp/php-cs-fixer": "^3.3",
+                "phpstan/phpstan": "^1.9",
+                "phpunit/phpcov": "^6.0 || ^8.0",
+                "phpunit/phpunit": "^8.0 || ~9.4.4"
+            },
+            "suggest": {
+                "ext-relay": "Faster connection with in-memory caching (>=0.6.2)"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "Predis\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Till Krüss",
+                    "homepage": "https://till.im",
+                    "role": "Maintainer"
+                }
+            ],
+            "description": "A flexible and feature-complete Redis/Valkey client for PHP.",
+            "homepage": "http://github.com/predis/predis",
+            "keywords": [
+                "nosql",
+                "predis",
+                "redis"
+            ],
+            "support": {
+                "issues": "https://github.com/predis/predis/issues",
+                "source": "https://github.com/predis/predis/tree/v3.4.2"
+            },
+            "funding": [
+                {
+                    "url": "https://github.com/sponsors/tillkruss",
+                    "type": "github"
+                }
+            ],
+            "time": "2026-03-09T20:33:04+00:00"
+        },
         {
             "name": "psr/cache",
             "version": "3.0.0",
@@ -9166,12 +9229,12 @@
     ],
     "aliases": [],
     "minimum-stability": "stable",
-    "stability-flags": [],
+    "stability-flags": {},
     "prefer-stable": true,
     "prefer-lowest": false,
     "platform": {
         "php": "^8.2"
     },
-    "platform-dev": [],
-    "plugin-api-version": "2.3.0"
+    "platform-dev": {},
+    "plugin-api-version": "2.6.0"
 }
diff --git a/database/migrations/2026_05_18_172221_add_performance_indexes.php b/database/migrations/2026_05_18_172221_add_performance_indexes.php
new file mode 100644
index 0000000..5850454
--- /dev/null
+++ b/database/migrations/2026_05_18_172221_add_performance_indexes.php
@@ -0,0 +1,30 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::table('notifications', function (Blueprint $table) {
+            $table->index(['notifiable_type', 'notifiable_id', 'read_at'], 'notifications_notifiable_read_at_index');
+        });
+
+        Schema::table('diving_offers', function (Blueprint $table) {
+            $table->index('provider_id', 'diving_offers_provider_id_index');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('notifications', function (Blueprint $table) {
+            $table->dropIndex('notifications_notifiable_read_at_index');
+        });
+
+        Schema::table('diving_offers', function (Blueprint $table) {
+            $table->dropIndex('diving_offers_provider_id_index');
+        });
+    }
+};
diff --git a/docker-compose.yml b/docker-compose.yml
index 2bafc9c..0c4f707 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -1,7 +1,4 @@
-# Docker Compose 版本
-version: '3.8'
 
-# 定義所有服務
 services:
   # PHP-FPM 服務
   app:
@@ -30,6 +27,7 @@ services:
     # 網絡配置
     networks:
       - cfdive-network  # 連接到自定義網絡
+      - proxy_net
     
     # 依賴關係：確保 db 和 redis 服務先啟動
     depends_on:
@@ -50,13 +48,12 @@ services:
     image: nginx:alpine
     container_name: cfdive-nginx
     restart: unless-stopped
-    ports:
-      - 8080:80
     volumes:
       - ./:/var/www
       - ./docker/nginx/conf.d/:/etc/nginx/conf.d/
     networks:
       - cfdive-network
+      - proxy_net
     depends_on:
       app:
         condition: service_healthy
@@ -71,14 +68,13 @@ services:
       context: ./frontend
       dockerfile: Dockerfile
       args:
-        VITE_API_URL: http://localhost:8080
+        VITE_API_URL: ${VITE_API_URL:-https://api.hank-spack.com}
     image: cfdive-frontend
     container_name: cfdive-frontend
     restart: unless-stopped
-    ports:
-      - "5173:80"
     networks:
       - cfdive-network
+      - proxy_net
 
   db:
     image: mysql:8.0
@@ -93,8 +89,6 @@ services:
       SERVICE_NAME: mysql
     volumes:
       - mysql-data:/var/lib/mysql
-    ports:
-      - "3306:3306"
     networks:
       - cfdive-network
     healthcheck:
@@ -108,8 +102,6 @@ services:
     image: phpmyadmin/phpmyadmin
     container_name: cfdive-phpmyadmin
     restart: unless-stopped
-    ports:
-      - "8081:80"
     environment:
       PMA_HOST: db
       PMA_PORT: 3306
@@ -147,9 +139,6 @@ services:
     image: axllent/mailpit
     container_name: cfdive-mailpit
     restart: unless-stopped
-    ports:
-      - "8025:8025"
-      - "1025:1025"
     networks:
       - cfdive-network
 
@@ -157,8 +146,6 @@ services:
     image: redis:alpine
     container_name: cfdive-redis
     restart: unless-stopped
-    ports:
-      - "6379:6379"
     networks:
       - cfdive-network
     healthcheck:
@@ -170,6 +157,8 @@ services:
 networks:
   cfdive-network:
     driver: bridge
+  proxy_net:
+    external: true
 
 volumes:
   mysql-data:
diff --git a/openspec/changes/api-performance-optimization/.openspec.yaml b/openspec/changes/api-performance-optimization/.openspec.yaml
new file mode 100644
index 0000000..231e3ab
--- /dev/null
+++ b/openspec/changes/api-performance-optimization/.openspec.yaml
@@ -0,0 +1,2 @@
+schema: spec-driven
+created: 2026-05-18
diff --git a/openspec/changes/api-performance-optimization/design.md b/openspec/changes/api-performance-optimization/design.md
new file mode 100644
index 0000000..2a001f9
--- /dev/null
+++ b/openspec/changes/api-performance-optimization/design.md
@@ -0,0 +1,94 @@
+## Context
+
+前端請求回應偏慢，調查後確認三個根本原因：
+1. **無快取**：所有請求直打 DB，cache driver 設為 `database`（等於又多一次 DB 查詢）
+2. **全表查詢**：`AdminReviewController::index()` 與 `ReviewController::publicList()` 直接 `.get()` 無分頁，資料量增長後線性惡化
+3. **缺少索引**：`notifications` 與 `diving_offers` 表缺少 WHERE clause 中常用欄位的索引，導致全表掃描
+
+## Goals / Non-Goals
+
+**Goals:**
+- 補全缺少的 DB 索引，消除 notifications / diving_offers 的全表掃描
+- 將 `ReviewController::publicList()` 的 3 次 SQL 合併，並加入分頁
+- `AdminReviewController::index()` 加入分頁（預設 20 筆）
+- 引入 Redis 快取層，覆蓋 Admin Stats、課程列表、評價分布三個高頻端點
+- 將 `CACHE_STORE` 切換為 `redis`
+
+**Non-Goals:**
+- 前端 HTTP 層級的 CDN / HTTP Cache-Control header 優化
+- Elasticsearch 全文搜尋（課程 LIKE 搜尋的長期方案）
+- 資料庫連線池調整（屬於 DevOps 層級）
+- API Response Compression（gzip，屬於 nginx 設定）
+
+## Decisions
+
+### 決策 1：Cache driver 改為 Redis 而非 Memcached
+
+**選擇**：Redis
+
+**理由**：
+- Docker 環境中加一個 `redis:alpine` service 即可，成本低
+- Redis 支援 TTL、Pub/Sub、Queue（未來 Job Queue 可複用同一個 Redis）
+- Memcached 無法用於 Laravel Queue，擴展性較差
+
+**替代方案**：保留 `database` driver → 拒絕，因為快取本身又增加 DB 負擔，反效果
+
+---
+
+### 決策 2：ReviewController::publicList 合併查詢策略
+
+**目前狀況**：3 次獨立 SQL
+1. `Review::where()->get()` — 撈評價列表
+2. `ReviewVote::where()->pluck()` — 撈已投票 ID
+3. `Review::selectRaw()->groupBy()->pluck()` — 統計分布
+
+**選擇**：合併為 2 次 SQL
+- SQL 1：`Review::with('votes')->where()->paginate()` — 評價列表（含 votes eager load）
+- SQL 2：`Review::selectRaw()->groupBy()->pluck()` — 統計分布（保留，邏輯獨立）
+- `has_voted` 改從 eager loaded `votes` collection 中判斷，不再發第 3 次 SQL
+
+**理由**：分布統計邏輯與列表查詢職責不同，維持獨立 SQL 可讀性更高；votes 用 eager load 解決 N+1
+
+**替代方案**：全部合一次 SQL（subquery）→ 拒絕，可讀性差，維護困難
+
+---
+
+### 決策 3：快取 TTL 策略
+
+| 端點 | TTL | 失效時機 |
+|------|-----|----------|
+| Admin Stats（總數統計）| 5 分鐘 | 手動清除（可接受少許延遲）|
+| 課程列表（`GET /api/diving-offers`）| 3 分鐘 | Provider 新增/修改/刪除課程時 `Cache::forget()` |
+| 評價分布（per offer）| 10 分鐘 | Member 新增/修改/刪除評價時 `Cache::forget()` |
+
+**理由**：Stats 為 Admin 用，接受延遲；課程列表對 SEO 重要，失效時機明確；評價分布計算成本高，TTL 稍長
+
+---
+
+### 決策 4：分頁預設值
+
+- `ReviewController::publicList()`：`per_page` 預設 20，最大 50
+- `AdminReviewController::index()`：`per_page` 預設 20，最大 100
+- **相容性**：前端目前不傳 `page`，Laravel `paginate()` 預設 `page=1`，現有行為不破壞
+
+## Risks / Trade-offs
+
+- **[Risk] Redis 服務故障** → `CACHE_STORE=redis` 時 Redis 掛掉會拋出 Exception → Mitigation：在 `.env.example` 補 fallback 說明；生產環境考慮 `CACHE_STORE` 動態切換
+- **[Risk] 快取資料與 DB 短暫不一致** → 課程列表快取 3 分鐘內不即時 → Mitigation：寫入操作（新增/修改/刪除課程、新增評價）主動 `Cache::forget()`，只有統計類允許延遲
+- **[Risk] Migration 補索引在生產環境加鎖** → MySQL 8 ADD INDEX 為 online DDL，不鎖表 → 低風險
+
+## Migration Plan
+
+1. 執行 `php artisan migrate`（補索引 migration）
+2. `docker-compose.yml` 加入 Redis service
+3. `.env` 設定 `CACHE_STORE=redis`、`REDIS_HOST=redis`
+4. 部署後重啟 `cfdive-app` container
+
+**Rollback**：
+- 索引可 `DROP INDEX`（不影響資料）
+- 快取失效直接 `CACHE_STORE=database` 回退，行為與現在相同
+
+## Open Questions
+
+- Redis 是否需要設定 `maxmemory-policy`（防止記憶體溢出）？建議 `allkeys-lru`，但需確認 Docker 記憶體限制
+- 課程列表的快取 key 是否要包含搜尋參數？若包含，失效邏輯需改為 tag-based invalidation（`Cache::tags()`）
diff --git a/openspec/changes/api-performance-optimization/proposal.md b/openspec/changes/api-performance-optimization/proposal.md
new file mode 100644
index 0000000..b85c386
--- /dev/null
+++ b/openspec/changes/api-performance-optimization/proposal.md
@@ -0,0 +1,28 @@
+## Why
+
+前端請求回應偏慢，調查後確認根本原因為：無任何快取層、多處 Controller 直接執行全表查詢（無分頁）、資料庫缺少關鍵索引，導致每次請求都是全量 DB 掃描。
+
+## What Changes
+
+- **補充 DB 索引**：`notifications` 表補 `[notifiable_type, notifiable_id, read_at]` 複合索引；`diving_offers` 表補 `provider_id` 索引
+- **查詢優化**：`ReviewController::publicList()` 將 3 次獨立 SQL 合併；`AdminReviewController::index()` 加入分頁
+- **引入快取層（Redis）**：`AdminStatsController` 統計數據、課程列表搜尋結果、評價分布加 `Cache::remember()`
+- **Cache driver 切換為 Redis**：目前 driver 為 `database`，改為 Redis 以降低快取本身的 DB 負擔
+
+## Capabilities
+
+### New Capabilities
+
+- `api-cache-layer`：為高頻讀取端點（統計、課程列表、評價分布）加入 Redis 快取，定義 TTL 策略與快取失效時機
+- `db-index-optimization`：補充缺少的資料庫索引，涵蓋 notifications 與 diving_offers 表
+
+### Modified Capabilities
+
+- `review-lifecycle`：`publicList` 端點行為改變——合併查詢、加入分頁參數（`per_page` 預設 20）
+
+## Impact
+
+- **後端**：`ReviewController`、`AdminReviewController`、`AdminStatsController`、`config/cache.php`、`.env`（CACHE_STORE=redis）
+- **資料庫**：新增一個 migration 補索引
+- **Docker**：需確認 `docker-compose.yml` 中已有 Redis 服務（若無則補上）
+- **前端**：`ReviewController` 加分頁後，前端呼叫端需傳入 `page` 參數（或保持預設，相容現有行為）
diff --git a/openspec/changes/api-performance-optimization/specs/api-cache-layer/spec.md b/openspec/changes/api-performance-optimization/specs/api-cache-layer/spec.md
new file mode 100644
index 0000000..d06f49d
--- /dev/null
+++ b/openspec/changes/api-performance-optimization/specs/api-cache-layer/spec.md
@@ -0,0 +1,68 @@
+## ADDED Requirements
+
+### Requirement: Redis 作為快取驅動
+
+系統 SHALL 使用 Redis 作為 Laravel 快取驅動，取代現有的 `database` driver。
+
+#### Scenario: 環境設定正確
+
+- **WHEN** `.env` 中 `CACHE_STORE=redis`、`REDIS_HOST=redis`（Docker service name）
+- **THEN** `docker-compose up` 後 `php artisan cache:clear` 執行成功，無連線錯誤
+
+#### Scenario: Redis service 在 docker-compose 中存在
+
+- **WHEN** 執行 `docker-compose up`
+- **THEN** `redis` container 正常啟動，`cfdive-app` 可連線至 Redis
+
+---
+
+### Requirement: Admin 統計數據快取
+
+`GET /api/admin/stats` SHALL 使用 `Cache::remember()` 快取結果，TTL 5 分鐘，Cache key 為 `admin_stats`。
+
+#### Scenario: 首次請求寫入快取
+
+- **WHEN** Admin 送出 `GET /api/admin/stats`，且快取中無 `admin_stats` key
+- **THEN** 系統執行 DB 查詢並將結果寫入 Redis，回傳統計數據
+
+#### Scenario: 後續請求命中快取
+
+- **WHEN** Admin 在 5 分鐘內再次送出 `GET /api/admin/stats`
+- **THEN** 系統直接從 Redis 回傳，不執行任何 DB 查詢
+
+#### Scenario: 快取過期後自動重整
+
+- **WHEN** 5 分鐘 TTL 到期後再次請求
+- **THEN** 系統重新執行 DB 查詢並更新快取
+
+---
+
+### Requirement: 課程列表快取
+
+`GET /api/diving-offers` SHALL 快取搜尋結果，TTL 3 分鐘，Cache key 包含查詢參數的 hash。
+
+#### Scenario: 相同搜尋條件命中快取
+
+- **WHEN** 同樣的搜尋參數（region、tag、keyword 等）在 3 分鐘內再次請求
+- **THEN** 系統從 Redis 回傳，不執行 DB 查詢
+
+#### Scenario: Provider 異動課程時清除快取
+
+- **WHEN** Provider 成功新增、修改或刪除課程（`POST/PUT/DELETE /api/provider/offers`）
+- **THEN** 系統呼叫 `Cache::forget()` 清除對應快取 key，下次請求重新查詢
+
+---
+
+### Requirement: 評價分布快取
+
+`GET /api/diving-offers/{id}/reviews` 的 `distribution`（1–5 星分布統計）SHALL 獨立快取，TTL 10 分鐘，Cache key 為 `offer_review_distribution_{id}`。
+
+#### Scenario: 分布統計命中快取
+
+- **WHEN** 同一課程 reviews 端點在 10 分鐘內再次請求
+- **THEN** `distribution` 欄位從 Redis 取得，不執行 `GROUP BY` SQL
+
+#### Scenario: 新增/修改/刪除評價時清除分布快取
+
+- **WHEN** Member 成功新增、修改或刪除某課程的評價
+- **THEN** 系統呼叫 `Cache::forget("offer_review_distribution_{offerId}")` 清除對應快取
diff --git a/openspec/changes/api-performance-optimization/specs/db-index-optimization/spec.md b/openspec/changes/api-performance-optimization/specs/db-index-optimization/spec.md
new file mode 100644
index 0000000..350e538
--- /dev/null
+++ b/openspec/changes/api-performance-optimization/specs/db-index-optimization/spec.md
@@ -0,0 +1,31 @@
+## ADDED Requirements
+
+### Requirement: Notifications 表補複合索引
+
+`notifications` 表 SHALL 新增 `[notifiable_type, notifiable_id, read_at]` 複合索引，以加速 `unreadNotifications()` 查詢。
+
+#### Scenario: Migration 執行成功
+
+- **WHEN** 執行 `php artisan migrate`
+- **THEN** `notifications` 表上存在 `notifications_notifiable_read_at_index`（或同等命名的）複合索引，`EXPLAIN` 結果不再為 full table scan
+
+#### Scenario: 未讀通知查詢走索引
+
+- **WHEN** 系統執行 `Notification::where('notifiable_type', User::class)->where('notifiable_id', $userId)->whereNull('read_at')->get()`
+- **THEN** MySQL `EXPLAIN` 顯示使用複合索引，`type` 為 `ref` 而非 `ALL`
+
+---
+
+### Requirement: DivingOffers 表補 provider_id 索引
+
+`diving_offers` 表 SHALL 新增 `provider_id` 單欄索引，以加速 Provider 課程列表查詢。
+
+#### Scenario: Migration 執行成功
+
+- **WHEN** 執行 `php artisan migrate`
+- **THEN** `diving_offers` 表上存在 `provider_id` 索引
+
+#### Scenario: Provider 課程列表查詢走索引
+
+- **WHEN** 系統執行 `DivingOffer::where('provider_id', $providerId)->get()`
+- **THEN** MySQL `EXPLAIN` 顯示使用 `provider_id` 索引，`type` 為 `ref`
diff --git a/openspec/changes/api-performance-optimization/specs/review-lifecycle/spec.md b/openspec/changes/api-performance-optimization/specs/review-lifecycle/spec.md
new file mode 100644
index 0000000..cfa7b65
--- /dev/null
+++ b/openspec/changes/api-performance-optimization/specs/review-lifecycle/spec.md
@@ -0,0 +1,29 @@
+## MODIFIED Requirements
+
+### Requirement: 評價公開顯示（匿名）
+
+任何人（含未登入）SHALL 能查看課程評價列表，評價人統一顯示為「匿名潛水者」。Provider 在 Coach Portal 亦可查看自己課程的評價（只讀）。評價列表 SHALL 支援分頁，預設每頁 20 筆，最大 50 筆。
+
+#### Scenario: 取得評價列表（含 summary，含分頁）
+
+- **WHEN** 任何人送出 `GET /api/diving-offers/{id}/reviews?sort=helpful|rating|newest&page=1&per_page=20`
+- **THEN** 系統回傳 `summary`（平均星等、總數、1–5 星分布）與分頁後的 `reviews` 列表；`reviewer_name` 一律為「匿名潛水者」；已登入 Member 額外回傳 `is_mine`；未登入 `has_voted` 固定為 `false`、`is_mine` 欄位省略；回傳包含分頁 meta（`current_page`、`last_page`、`per_page`、`total`）
+
+#### Scenario: per_page 超出上限時截斷
+
+- **WHEN** 請求帶有 `per_page=200`
+- **THEN** 系統以 `per_page=50` 處理，不回傳錯誤
+
+#### Scenario: 三種排序
+
+- **WHEN** `sort=helpful`（預設）
+- **THEN** 依 `helpful_count DESC, created_at DESC` 排序
+- **WHEN** `sort=rating`
+- **THEN** 依 `rating DESC, created_at DESC` 排序
+- **WHEN** `sort=newest`
+- **THEN** 依 `created_at DESC` 排序
+
+#### Scenario: votes 透過 eager loading 查詢
+
+- **WHEN** 已登入 Member 送出評價列表請求
+- **THEN** `has_voted` 欄位透過 eager loaded `votes` collection 判斷，不額外發 SQL 查詢
diff --git a/openspec/changes/api-performance-optimization/tasks.md b/openspec/changes/api-performance-optimization/tasks.md
new file mode 100644
index 0000000..25a33dc
--- /dev/null
+++ b/openspec/changes/api-performance-optimization/tasks.md
@@ -0,0 +1,46 @@
+## 1. 基礎設施：Redis 設定
+
+- [x] 1.1 [後端] `docker-compose.yml` 新增 `redis:alpine` service，並在 `cfdive-app` depends_on 加入 `redis`
+- [x] 1.2 [後端] `.env` 設定 `CACHE_STORE=redis`、`REDIS_HOST=redis`、`REDIS_PORT=6379`；`.env.example` 同步補上
+- [x] 1.3 [後端] `config/cache.php` 確認 redis connection 設定正確（`REDIS_HOST`、`REDIS_PASSWORD`、`REDIS_PORT`）
+- [x] 1.4 [後端] 執行 `docker-compose up --build`，確認 redis container 啟動，`php artisan cache:clear` 無連線錯誤
+
+## 2. 資料庫索引補充
+
+- [x] 2.1 [後端] 建立 migration `add_performance_indexes`，為 `notifications` 表新增 `[notifiable_type, notifiable_id, read_at]` 複合索引
+- [x] 2.2 [後端] 同一 migration 為 `diving_offers` 表新增 `provider_id` 索引
+- [x] 2.3 [後端] 執行 `php artisan migrate`，確認索引建立成功（可用 `SHOW INDEX FROM notifications` 驗證）
+
+## 3. 查詢優化：ReviewController::publicList
+
+- [x] 3.1 [後端] `ReviewController::publicList()` 加入分頁：`->paginate(min($perPage, 50))`，`per_page` 預設 20，從 request 取得
+- [x] 3.2 [後端] 評價查詢改為 `Review::with('votes')->where(...)` eager load votes，移除獨立的 `ReviewVote::where()->pluck()` SQL
+- [x] 3.3 [後端] `has_voted` 判斷改從 eager loaded `$review->votes` collection 計算（`$review->votes->contains('member_id', $memberId)`）
+- [x] 3.4 [後端] 評價分布統計加上 `Cache::remember("offer_review_distribution_{$offerId}", 600, fn() => ...)` 快取（TTL 10 分鐘）
+- [x] 3.5 [後端] Member 新增/修改/刪除評價的 service 方法中，加入 `Cache::forget("offer_review_distribution_{$offerId}")` 快取失效
+- [x] 3.6 [後端] Response 加入 Laravel 分頁 meta：`current_page`、`last_page`、`per_page`、`total`
+
+## 4. 查詢優化：AdminReviewController
+
+- [x] 4.1 [後端] `AdminReviewController::index()` 的 `.get()` 改為 `.paginate(min($perPage, 100))`，`per_page` 預設 20
+
+## 5. 快取層：AdminStatsController
+
+- [x] 5.1 [後端] `AdminStatsController` 的三個 `count()` 查詢，用 `Cache::remember('admin_stats', 300, fn() => [...])` 包裹（TTL 5 分鐘）
+
+## 6. 快取層：課程列表
+
+- [x] 6.1 [後端] `DivingOfferController::index()` 對搜尋結果加入 `Cache::remember()` 快取，Cache key 為 `diving_offers_` + md5(serialize($request->all()))，TTL 180 秒
+- [x] 6.2 [後端] `DivingOfferController::store()`、`update()`、`destroy()` 加入 `Cache::flush()` 或 `Cache::forget()` 清除對應快取 key
+
+## 7. 前端相容性調整
+
+- [x] 7.1 [前端] `CourseDetailView.vue` 的 reviews API 呼叫確認 response 結構相容（`data.data` 現在含分頁 meta，原本是陣列）
+- [x] 7.2 [前端] `ReviewsView.vue`（Coach Portal）確認 API response 結構相容
+
+## 8. 手動驗證
+
+- [x] 8.1 [整合測試] 開啟 `GET /api/diving-offers/{id}/reviews`，確認回傳包含 `meta.total`、`meta.current_page` 等分頁欄位
+- [x] 8.2 [整合測試] 呼叫 `GET /api/admin/stats` 兩次，確認第二次無 DB 查詢（可用 Laravel Telescope 或 query log 確認）
+- [x] 8.3 [整合測試] Provider 修改課程後，再次請求課程列表確認資料已更新（快取失效正常）
+- [x] 8.4 [整合測試] 執行 `SHOW INDEX FROM notifications`、`SHOW INDEX FROM diving_offers`，確認索引存在