diff --git a/.github/workflows/ai-pr-review.yml b/.github/workflows/ai-pr-review.yml
new file mode 100644
index 0000000..fda4b31
--- /dev/null
+++ b/.github/workflows/ai-pr-review.yml
@@ -0,0 +1,81 @@
+name: AI Code Review
+
+on:
+  pull_request:
+    types: [opened, synchronize]
+
+jobs:
+  ai-review:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: write
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - uses: actions/github-script@v7
+        env:
+          OPENROUTER_API_KEY: ${{ secrets.OPENROUTER_API_KEY }}
+        with:
+          script: |
+            const diff = await github.rest.repos.compareCommits({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              base: context.payload.pull_request.base.sha,
+              head: context.payload.pull_request.head.sha
+            });
+
+            const kotlinFiles = diff.data.files.filter(file =>
+              (file.filename.endsWith('.kt') || file.filename.endsWith('.kts')) && file.patch
+            );
+
+            if (kotlinFiles.length === 0) return;
+
+            for (const file of kotlinFiles.slice(0, 3)) {
+              const response = await fetch('https://openrouter.ai/api/v1/chat/completions', {
+                method: 'POST',
+                headers: {
+                  'Authorization': `Bearer ${process.env.OPENROUTER_API_KEY}`,
+                  'Content-Type': 'application/json'
+                },
+                body: JSON.stringify({
+                  model: 'x-ai/grok-4-fast:free',
+                  messages: [{
+                    role: 'system',
+                    content: `코드 리뷰어입니다. 다음 규칙을 검토하세요:
+
+## 필수 검토 항목
+1. **글로벌 익셉션 처리**: @ControllerAdvice 사용, 표준 에러 응답
+2. **ApiResponse 사용**: 모든 API는 ApiResponse<T>로 감싸서 응답
+3. **Kotlin 최적화**: data class, null safety, when 표현식, 확장함수 등
+4. **ktlint 규칙**: 포맷팅, 네이밍 컨벤션
+
+## 응답 형식
+🟢 **좋은점**: [규칙을 잘 지킨 부분]
+🟡 **개선사항**: [더 좋게 할 수 있는 부분]
+🔴 **문제점**: [반드시 수정해야 할 부분]`
+                  }, {
+                    role: 'user',
+                    content: `파일: ${file.filename}\n\n변경사항:\n${file.patch}`
+                  }],
+                  max_tokens: 500,
+                  temperature: 0
+                })
+              });
+
+              if (response.ok) {
+                const result = await response.json();
+                const review = result.choices[0].message.content;
+
+                await github.rest.pulls.createReview({
+                  owner: context.repo.owner,
+                  repo: context.repo.repo,
+                  pull_number: context.payload.pull_request.number,
+                  body: `## 🤖 AI 리뷰 - \`${file.filename}\`\n\n${review}`,
+                  event: 'COMMENT'
+                });
+              }
+            }
\ No newline at end of file
diff --git a/docs/erd-diagram.md b/docs/erd-diagram.md
index 239077e..cdfc7bf 100644
--- a/docs/erd-diagram.md
+++ b/docs/erd-diagram.md
@@ -47,7 +47,6 @@ erDiagram
         bigint session_id FK "세션 ID"
         text content "메시지 내용"
         enum sender_type "USER, AI"
-        json metadata "AI 도구 사용 정보"
         datetime created_at "메시지 전송 시간"
     }
 
@@ -143,7 +142,6 @@ AI 채팅 메시지를 저장하는 테이블입니다.
 | session_id | BIGINT | FK, NOT NULL | 세션 ID |
 | content | TEXT | NOT NULL | 메시지 내용 |
 | sender_type | ENUM | NOT NULL | 발신자 유형 (USER, AI) |
-| metadata | JSON | NULL | AI 도구 사용 정보 (WeatherTool, TourTool) |
 | created_at | DATETIME | NOT NULL | 메시지 전송 시간 |
 
 **제약조건:**
@@ -243,7 +241,7 @@ Guest가 AI 채팅 세션과 채팅방을 평가하는 테이블입니다.
 1. User → AiChatSession 생성
 2. User → AiChatMessage 전송
 3. Spring AI → WeatherTool/TourTool 호출
-4. AI → AiChatMessage(sender_type=AI) 생성 + metadata 저장
+4. AI → AiChatMessage(sender_type=AI) 생성
 5. SSE로 실시간 응답 전송
 ```
 
diff --git a/src/main/kotlin/com/back/koreaTravelGuide/domain/ai/aiChat/entity/AiChatMessage.kt b/src/main/kotlin/com/back/koreaTravelGuide/domain/ai/aiChat/entity/AiChatMessage.kt
new file mode 100644
index 0000000..184155e
--- /dev/null
+++ b/src/main/kotlin/com/back/koreaTravelGuide/domain/ai/aiChat/entity/AiChatMessage.kt
@@ -0,0 +1,34 @@
+package com.back.koreaTravelGuide.domain.ai.aiChat.entity
+
+import jakarta.persistence.Column
+import jakarta.persistence.Entity
+import jakarta.persistence.EnumType
+import jakarta.persistence.Enumerated
+import jakarta.persistence.FetchType
+import jakarta.persistence.GeneratedValue
+import jakarta.persistence.GenerationType
+import jakarta.persistence.Id
+import jakarta.persistence.JoinColumn
+import jakarta.persistence.ManyToOne
+import jakarta.persistence.Table
+import java.time.ZoneId
+import java.time.ZonedDateTime
+
+@Entity
+@Table(name = "ai_chat_messages")
+class AiChatMessage(
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    @Column(name = "id")
+    val id: Long? = null,
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "session_id", nullable = false)
+    val aiChatSession: AiChatSession,
+    @Column(name = "content", columnDefinition = "TEXT", nullable = false)
+    val content: String,
+    @Enumerated(EnumType.STRING)
+    @Column(name = "sender_type", nullable = false)
+    val senderType: SenderType,
+    @Column(name = "created_at", nullable = false)
+    val createdAt: ZonedDateTime = ZonedDateTime.now(ZoneId.of("Asia/Seoul")),
+)
diff --git a/src/main/kotlin/com/back/koreaTravelGuide/domain/ai/aiChat/entity/AiChatSession.kt b/src/main/kotlin/com/back/koreaTravelGuide/domain/ai/aiChat/entity/AiChatSession.kt
new file mode 100644
index 0000000..bbf9fe3
--- /dev/null
+++ b/src/main/kotlin/com/back/koreaTravelGuide/domain/ai/aiChat/entity/AiChatSession.kt
@@ -0,0 +1,25 @@
+package com.back.koreaTravelGuide.domain.ai.aiChat.entity
+
+import jakarta.persistence.Column
+import jakarta.persistence.Entity
+import jakarta.persistence.GeneratedValue
+import jakarta.persistence.GenerationType
+import jakarta.persistence.Id
+import jakarta.persistence.Table
+import java.time.ZoneId
+import java.time.ZonedDateTime
+
+@Entity
+@Table(name = "ai_chat_sessions")
+class AiChatSession(
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    @Column(name = "id")
+    val id: Long? = null,
+    @Column(name = "user_id", nullable = false)
+    val userId: Long,
+    @Column(name = "session_title", nullable = true, length = 100)
+    var sessionTitle: String? = null,
+    @Column(name = "created_at", nullable = false)
+    val createdAt: ZonedDateTime = ZonedDateTime.now(ZoneId.of("Asia/Seoul")),
+)
diff --git a/src/main/kotlin/com/back/koreaTravelGuide/domain/ai/aiChat/entity/ChatHistory.kt b/src/main/kotlin/com/back/koreaTravelGuide/domain/ai/aiChat/entity/ChatHistory.kt
deleted file mode 100644
index c3c7619..0000000
--- a/src/main/kotlin/com/back/koreaTravelGuide/domain/ai/aiChat/entity/ChatHistory.kt
+++ /dev/null
@@ -1,4 +0,0 @@
-package com.back.koreaTravelGuide.domain.ai.aiChat.entity
-
-// TODO: 채팅 기록 엔티티 - 대화 내용 저장 (향후 구현)
-class ChatHistory
diff --git a/src/main/kotlin/com/back/koreaTravelGuide/domain/ai/aiChat/entity/SenderType.kt b/src/main/kotlin/com/back/koreaTravelGuide/domain/ai/aiChat/entity/SenderType.kt
new file mode 100644
index 0000000..04c644f
--- /dev/null
+++ b/src/main/kotlin/com/back/koreaTravelGuide/domain/ai/aiChat/entity/SenderType.kt
@@ -0,0 +1,6 @@
+package com.back.koreaTravelGuide.domain.ai.aiChat.entity
+
+enum class SenderType {
+    USER,
+    AI,
+}