diff --git a/backend/cmd/server/main.go b/backend/cmd/server/main.go
index 2a6275b..8accba9 100644
--- a/backend/cmd/server/main.go
+++ b/backend/cmd/server/main.go
@@ -22,6 +22,7 @@ import (
 	"github.com/hhs/camtalk/internal/session"
 	"github.com/hhs/camtalk/internal/store"
 	"github.com/hhs/camtalk/internal/ws"
+	migrations "github.com/hhs/camtalk/migrations"
 )
 
 // Version 通过构建时 -ldflags 注入，如：
@@ -50,27 +51,39 @@ func main() {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
+	var userRepo store.UserRepository
+	var msgRepo store.MessageRepository
+
 	if cfg.Storage.Driver == "postgres" {
 		pool, err := store.NewPostgresPool(ctx, cfg.Storage.DSN)
 		if err != nil {
 			logger.Log.Fatalw("failed to connect to postgres", "error", err)
 		}
 		defer pool.Close()
-		logger.Log.Infow("postgres connected", "driver", cfg.Storage.Driver)
-		// TODO: Phase 2 - 初始化 UserRepository 和 MessageRepository
-		_ = pool
+
+		// 执行数据库迁移
+		if err := store.RunMigrations(ctx, pool, migrations.FS); err != nil {
+			logger.Log.Fatalw("failed to run migrations", "error", err)
+		}
+
+		userRepo = store.NewPgUserRepository(pool)
+		msgRepo = store.NewPgMessageRepository(pool)
+		logger.Log.Infow("postgres storage initialized", "driver", cfg.Storage.Driver)
+	} else {
+		userRepo = store.NewMemUserRepository()
+		logger.Log.Info("using in-memory storage")
 	}
 
-	// 初始化 UserRepository（内存模式用于无 DB 场景）
-	var userRepo store.UserRepository
-	userRepo = store.NewMemUserRepository()
-
-	// 初始化 Session Manager（MVP 默认内存实现）
+	// 初始化 Session Manager
 	var sessionMgr session.Manager
-	// TODO: 当 Redis 配置非空时切换为 RedisManager
+	var sessionOpts []session.Option
+	if msgRepo != nil {
+		sessionOpts = append(sessionOpts, session.WithMessageRepository(msgRepo))
+	}
 	sessionMgr = session.NewMemoryManager(
 		time.Duration(cfg.Session.TTL)*time.Minute,
 		cfg.Session.MaxHistory,
+		sessionOpts...,
 	)
 	defer sessionMgr.(*session.MemoryManager).Stop()
 
@@ -141,7 +154,7 @@ func main() {
 	authHandler.RegisterRoutes(apiGroup)
 
 	// Conversation REST 端点
-	convHandler := api.NewConversationHandler(sessionMgr, tokenMgr)
+	convHandler := api.NewConversationHandler(sessionMgr, tokenMgr, msgRepo)
 	convHandler.RegisterRoutes(apiGroup)
 
 	// WebSocket
diff --git a/backend/internal/api/conversation.go b/backend/internal/api/conversation.go
index f95e2c1..728cc9a 100644
--- a/backend/internal/api/conversation.go
+++ b/backend/internal/api/conversation.go
@@ -12,19 +12,23 @@ import (
 	apperr "github.com/hhs/camtalk/internal/errors"
 	"github.com/hhs/camtalk/internal/models"
 	"github.com/hhs/camtalk/internal/session"
+	"github.com/hhs/camtalk/internal/store"
 )
 
 // ConversationHandler 提供对话相关的 REST 端点。
 type ConversationHandler struct {
 	sessionMgr session.Manager
 	tokenMgr   *auth.TokenManager
+	msgRepo    store.MessageRepository // 可选，为 nil 时 fallback 到内存查询
 }
 
 // NewConversationHandler 创建 ConversationHandler。
-func NewConversationHandler(sessionMgr session.Manager, tokenMgr *auth.TokenManager) *ConversationHandler {
+// msgRepo 可选，为 nil 时消息查询走内存。
+func NewConversationHandler(sessionMgr session.Manager, tokenMgr *auth.TokenManager, msgRepo store.MessageRepository) *ConversationHandler {
 	return &ConversationHandler{
 		sessionMgr: sessionMgr,
 		tokenMgr:   tokenMgr,
+		msgRepo:    msgRepo,
 	}
 }
 
@@ -215,7 +219,7 @@ func (h *ConversationHandler) Delete(c *gin.Context) {
 //
 // 查询参数：
 //   - limit: 返回消息数量上限，默认 50
-//   - before: 消息偏移量（用于分页），返回此偏移量之前的消息
+//   - before: 消息 ID 游标（用于分页），返回此 ID 之前的消息
 func (h *ConversationHandler) GetMessages(c *gin.Context) {
 	sessionID := c.Param("id")
 
@@ -229,9 +233,27 @@ func (h *ConversationHandler) GetMessages(c *gin.Context) {
 		limit = 50
 	}
 
-	before, _ := strconv.Atoi(c.DefaultQuery("before", "0"))
+	beforeID, _ := strconv.ParseInt(c.DefaultQuery("before", "0"), 10, 64)
 
-	// 获取全量历史（内存实现中 history 是全量存储的）
+	// 优先从 PostgreSQL 查询（支持持久化后的全量历史）
+	if h.msgRepo != nil {
+		messages, err := h.msgRepo.GetMessages(c.Request.Context(), sessionID, limit, beforeID)
+		if err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{
+				"code":    apperr.CodeInternalError,
+				"message": "failed to get messages",
+			})
+			return
+		}
+		count, _ := h.msgRepo.GetMessageCount(c.Request.Context(), sessionID)
+		c.JSON(http.StatusOK, gin.H{
+			"messages": messages,
+			"total":    count,
+		})
+		return
+	}
+
+	// fallback：从内存查询
 	allMessages, err := h.sessionMgr.GetHistory(c.Request.Context(), sessionID, 0)
 	if err != nil {
 		if errors.Is(err, session.ErrSessionNotFound) {
@@ -250,9 +272,9 @@ func (h *ConversationHandler) GetMessages(c *gin.Context) {
 
 	total := len(allMessages)
 
-	// before > 0 表示取 before 之前的消息（不含 before 位置）
-	if before > 0 && before <= total {
-		allMessages = allMessages[:before]
+	// beforeID > 0 时表示偏移量（兼容旧接口语义）
+	if beforeID > 0 && int(beforeID) <= total {
+		allMessages = allMessages[:beforeID]
 	}
 
 	// 取最后 limit 条
diff --git a/backend/internal/api/conversation_test.go b/backend/internal/api/conversation_test.go
index 6b873fc..468d172 100644
--- a/backend/internal/api/conversation_test.go
+++ b/backend/internal/api/conversation_test.go
@@ -93,7 +93,7 @@ func newConvTestRouter(mgr session.Manager) (*gin.Engine, *auth.TokenManager) {
 	gin.SetMode(gin.TestMode)
 	r := gin.New()
 	tm := auth.NewTokenManager("test-secret", 15*time.Minute, 7*24*time.Hour)
-	h := api.NewConversationHandler(mgr, tm)
+	h := api.NewConversationHandler(mgr, tm, nil)
 	h.RegisterRoutes(r.Group("/api"))
 	return r, tm
 }
diff --git a/backend/internal/store/migrate.go b/backend/internal/store/migrate.go
new file mode 100644
index 0000000..b3ea4ba
--- /dev/null
+++ b/backend/internal/store/migrate.go
@@ -0,0 +1,80 @@
+package store
+
+import (
+	"context"
+	"fmt"
+	"io/fs"
+	"sort"
+	"strings"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+
+	"github.com/hhs/camtalk/internal/logger"
+)
+
+// RunMigrations 从给定的 fs.FS 中读取 *.up.sql 文件并按版本号顺序执行。
+// 已执行过的版本会跳过（通过 schema_migrations 表记录）。
+func RunMigrations(ctx context.Context, pool *pgxpool.Pool, fsys fs.FS) error {
+	// 确保 schema_migrations 表存在
+	if _, err := pool.Exec(ctx, `CREATE TABLE IF NOT EXISTS schema_migrations (
+		version INTEGER PRIMARY KEY,
+		applied_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+	)`); err != nil {
+		return fmt.Errorf("create schema_migrations table: %w", err)
+	}
+
+	// 收集所有 *.up.sql 文件
+	entries, err := fs.ReadDir(fsys, ".")
+	if err != nil {
+		return fmt.Errorf("read migrations dir: %w", err)
+	}
+
+	var files []string
+	for _, e := range entries {
+		if !e.IsDir() && strings.HasSuffix(e.Name(), ".up.sql") {
+			files = append(files, e.Name())
+		}
+	}
+	sort.Strings(files)
+
+	for _, name := range files {
+		// 从文件名提取版本号，如 "001_users.up.sql" → 1
+		var version int
+		if _, err := fmt.Sscanf(name, "%d_", &version); err != nil {
+			return fmt.Errorf("parse version from %s: %w", name, err)
+		}
+
+		// 检查是否已执行
+		var exists bool
+		if err := pool.QueryRow(ctx,
+			`SELECT EXISTS(SELECT 1 FROM schema_migrations WHERE version = $1)`, version,
+		).Scan(&exists); err != nil {
+			return fmt.Errorf("check migration version %d: %w", version, err)
+		}
+		if exists {
+			logger.Log.Debugw("migration already applied", "version", version, "file", name)
+			continue
+		}
+
+		// 读取并执行
+		content, err := fs.ReadFile(fsys, name)
+		if err != nil {
+			return fmt.Errorf("read migration %s: %w", name, err)
+		}
+
+		if _, err := pool.Exec(ctx, string(content)); err != nil {
+			return fmt.Errorf("execute migration %s: %w", name, err)
+		}
+
+		// 记录已执行
+		if _, err := pool.Exec(ctx,
+			`INSERT INTO schema_migrations (version) VALUES ($1)`, version,
+		); err != nil {
+			return fmt.Errorf("record migration %d: %w", version, err)
+		}
+
+		logger.Log.Infow("migration applied", "version", version, "file", name)
+	}
+
+	return nil
+}
diff --git a/backend/migrations/embed.go b/backend/migrations/embed.go
new file mode 100644
index 0000000..9b6970b
--- /dev/null
+++ b/backend/migrations/embed.go
@@ -0,0 +1,9 @@
+// Package migrations 提供数据库迁移 SQL 文件的嵌入式访问。
+package migrations
+
+import "embed"
+
+// FS 包含所有迁移 SQL 文件。
+//
+//go:embed *.sql
+var FS embed.FS
diff --git a/docker-compose.yml b/docker-compose.yml
index f5f15de..053f375 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -19,10 +19,32 @@ services:
     container_name: camtalk-backend
     environment:
       - APP_ENV=production
+      - CAMTALK_STORAGE_DRIVER=postgres
+      - CAMTALK_STORAGE_DSN=postgres://camtalk:camtalk123@postgres:5432/camtalk?sslmode=disable
+      - CAMTALK_AUTH_JWT_SECRET=78uWBBAF8XEQEotKDlrnlnd4y8i4WN3E4zXmNmC8BYQ=
+    depends_on:
+      - postgres
     networks:
       - camtalk-net
     restart: unless-stopped
 
+  postgres:
+    # 阿里云镜像，避免从 Docker Hub 拉取超时
+    image: registry.cn-hangzhou.aliyuncs.com/library/postgres:15-alpine
+    container_name: camtalk-postgres
+    environment:
+      POSTGRES_USER: camtalk
+      POSTGRES_PASSWORD: camtalk123
+      POSTGRES_DB: camtalk
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+    networks:
+      - camtalk-net
+    restart: unless-stopped
+
+volumes:
+  pgdata:
+
 networks:
   camtalk-net:
     driver: bridge