From f4515ce5e499d7bfb8d730765ebfda803eb9e115 Mon Sep 17 00:00:00 2001
From: hhs <386998068@qq.com>
Date: Sun, 14 Jun 2026 17:54:33 +0800
Subject: [PATCH] =?UTF-8?q?feat:=20Phase=208.3=20=E2=80=94=20Session=20Man?=
 =?UTF-8?q?ager=20=E6=B3=A8=E5=85=A5=20MessageRepository=EF=BC=8CAppendMes?=
 =?UTF-8?q?sage=20=E5=90=AF=E7=94=A8=20Write-Through?=
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---
 backend/internal/session/memory.go | 33 ++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

diff --git a/backend/internal/session/memory.go b/backend/internal/session/memory.go
index 2df0be3..be8da3c 100644
--- a/backend/internal/session/memory.go
+++ b/backend/internal/session/memory.go
@@ -10,6 +10,7 @@ import (
 
 	"github.com/hhs/camtalk/internal/logger"
 	"github.com/hhs/camtalk/internal/models"
+	"github.com/hhs/camtalk/internal/store"
 )
 
 const (
@@ -33,11 +34,23 @@ type MemoryManager struct {
 	ttl         time.Duration
 	maxHistory  int
 	stopCleaner chan struct{}
+	msgRepo     store.MessageRepository // 可选，消息持久化（Write-Through）
+}
+
+// Option MemoryManager 的函数式选项。
+type Option func(*MemoryManager)
+
+// WithMessageRepository 注入消息持久化仓库，启用 Write-Through 模式。
+func WithMessageRepository(repo store.MessageRepository) Option {
+	return func(m *MemoryManager) {
+		m.msgRepo = repo
+	}
 }
 
 // NewMemoryManager 创建内存版 SessionManager。
 // ttl 为会话过期时间，maxHistory 为对话历史上限（0 表示使用默认值 20）。
-func NewMemoryManager(ttl time.Duration, maxHistory int) *MemoryManager {
+// opts 为可选配置，如 WithMessageRepository 启用消息持久化。
+func NewMemoryManager(ttl time.Duration, maxHistory int, opts ...Option) *MemoryManager {
 	if ttl <= 0 {
 		ttl = defaultTTL
 	}
@@ -52,6 +65,10 @@ func NewMemoryManager(ttl time.Duration, maxHistory int) *MemoryManager {
 		stopCleaner: make(chan struct{}),
 	}
 
+	for _, opt := range opts {
+		opt(m)
+	}
+
 	// 启动后台清理 goroutine，每分钟清除过期会话。
 	go m.cleanLoop()
 
@@ -242,12 +259,13 @@ func (m *MemoryManager) GetHistory(_ context.Context, sessionID string, limit in
 }
 
 // AppendMessage 追加一条对话消息，同时刷新 TTL。
+// 若配置了 MessageRepository，消息会异步写入 PostgreSQL（Write-Through）。
 func (m *MemoryManager) AppendMessage(_ context.Context, sessionID string, msg models.Message) error {
 	m.mu.Lock()
-	defer m.mu.Unlock()
 
 	entry, ok := m.sessions[sessionID]
 	if !ok || m.isExpired(entry) {
+		m.mu.Unlock()
 		return ErrSessionNotFound
 	}
 
@@ -266,6 +284,17 @@ func (m *MemoryManager) AppendMessage(_ context.Context, sessionID string, msg m
 	now := time.Now()
 	entry.lastActive = now
 	entry.session.UpdatedAt = now
+	m.mu.Unlock()
+
+	// Write-Through：异步写冷存储，不阻塞调用方
+	if m.msgRepo != nil {
+		go func() {
+			if err := m.msgRepo.SaveMessage(context.Background(), sessionID, msg, 0); err != nil {
+				logger.Log.Warnw("persist message failed", "session", sessionID, "error", err)
+			}
+		}()
+	}
+
 	return nil
 }