2026-06-14 21:25:32 +08:00
47 changed files with 6615 additions and 521 deletions
--- a/.env.example
+++ b/.env.example
@@ -0,0 +1,21 @@
+# CamTalk 环境变量模板
+# 复制为 .env 并填入实际值：cp .env.example .env
+# .env 已在 .gitignore 中，不会提交到版本控制
+
+# ---- AI 服务 API Key ----
+CAMTALK_AI_LLM_API_KEY=sk-xxx
+CAMTALK_AI_STT_API_KEY=
+CAMTALK_AI_TTS_API_KEY=
+
+# ---- 可选覆盖（默认值见 config.yaml）----
+# CAMTALK_AI_LLM_MODEL=gpt-4o
+# CAMTALK_AI_LLM_ENDPOINT=https://api.openai.com/v1
+# CAMTALK_AI_LLM_TIMEOUT=10
+# CAMTALK_AI_STT_ENDPOINT=wss://api.deepgram.com/v1/listen
+# CAMTALK_AI_TTS_ENDPOINT=https://api.openai.com/v1
+# CAMTALK_AI_TTS_VOICE=alloy
+# CAMTALK_AI_TTS_SPEED=1.0
+# CAMTALK_AI_TTS_TIMEOUT=5
+
+# ---- 应用 ----
+# APP_ENV=dev
--- a/.gitignore
+++ b/.gitignore
@@ -4,6 +4,7 @@ frontend/dist/

 # ---- 后端 ----
 backend/bin/
+backend/server

 # ---- 环境变量 ----
 .env
@@ -18,5 +19,11 @@ Thumbs.db
 .idea/
 .vscode/

+# ---- Playwright MCP ----
+.playwright-mcp/
+
+# ---- 截图 ----
+*.png
+
 # ---- Obsidian ----
 .obsidian/
--- a/backend/.gitignore
+++ b/backend/.gitignore
@@ -0,0 +1,17 @@
+# 编译产物
+/server
+bin/
+
+# 环境配置
+.env
+config.dev.yaml
+config.prod.yaml
+
+# 临时文件
+tmp/
+
+# IDE
+.idea/
+.vscode/
+*.swp
+*.swo
--- a/backend/cmd/server/main.go
+++ b/backend/cmd/server/main.go
@@ -1,40 +1,118 @@
 package main

 import (
-	"log"
+	"context"
+	"errors"
+	"net/http"
+	"os/signal"
+	"syscall"
 	"time"

 	"github.com/gin-gonic/gin"

+	"github.com/hhs/camtalk/internal/api"
+	"github.com/hhs/camtalk/internal/ai/llm"
+	"github.com/hhs/camtalk/internal/ai/stt"
+	"github.com/hhs/camtalk/internal/ai/tts"
+	"github.com/hhs/camtalk/internal/config"
+	"github.com/hhs/camtalk/internal/logger"
+	"github.com/hhs/camtalk/internal/orchestrator"
+	"github.com/hhs/camtalk/internal/session"
 	"github.com/hhs/camtalk/internal/ws"
 )

 var startTime = time.Now()

 func main() {
-	r := gin.Default()
+	// 加载配置
+	cfg, err := config.Load()
+	if err != nil {
+		panic("failed to load config: " + err.Error())
+	}
+
+	// 初始化日志
+	logger.Init(cfg.Log.Level, cfg.Log.Format)
+	defer logger.Sync()
+
+	logger.Log.Infow("config loaded",
+		"env", cfg.App.Env,
+		"addr", cfg.Server.Addr(),
+	)
+
+	// 初始化 Session Manager（MVP 默认内存实现）
+	var sessionMgr session.Manager
+	// TODO: 当 Redis 配置非空时切换为 RedisManager
+	sessionMgr = session.NewMemoryManager(30*time.Minute, 20)
+	defer sessionMgr.(*session.MemoryManager).Stop()
+
+	// 初始化 AI 服务
+	sttService := stt.NewDeepgramService(cfg.AI.STT.APIKey, cfg.AI.STT.Model, cfg.AI.STT.Endpoint, logger.Log)
+	llmService := llm.NewOpenAIService(cfg.AI.LLM.APIKey, cfg.AI.LLM.Model, cfg.AI.LLM.Endpoint, cfg.AI.LLM.Timeout, logger.Log)
+	ttsService := tts.NewOpenAIService(cfg.AI.TTS.APIKey, cfg.AI.TTS.Model, cfg.AI.TTS.Voice, cfg.AI.TTS.Endpoint, cfg.AI.TTS.Speed, cfg.AI.TTS.Timeout, logger.Log)
+
+	// 初始化 Orchestrator
+	orch := orchestrator.New(sttService, llmService, ttsService, sessionMgr, cfg.AI.LLM.Model)
+
+	// Gin 模式
+	if cfg.App.Env == "prod" {
+		gin.SetMode(gin.ReleaseMode)
+	}
+
+	r := gin.New()
+	r.Use(gin.Recovery())

 	// REST API
-	api := r.Group("/api")
+	apiGroup := r.Group("/api")
 	{
-		api.GET("/health", healthHandler)
+		apiGroup.GET("/health", healthHandler(sessionMgr))
 	}

+	// Session REST 端点
+	sessionHandler := api.NewSessionHandler(sessionMgr)
+	sessionHandler.RegisterRoutes(apiGroup)
+
 	// WebSocket
-	r.GET("/ws", ws.ServeWS)
+	r.GET("/ws", ws.ServeWS(sessionMgr, orch))

-	log.Println("CamTalk gateway starting on :8080")
-	if err := r.Run(":8080"); err != nil {
-		log.Fatalf("failed to start server: %v", err)
+	// HTTP Server
+	srv := &http.Server{
+		Addr:         cfg.Server.Addr(),
+		Handler:      r,
+		ReadTimeout:  time.Duration(cfg.Server.ReadTimeout) * time.Second,
+		WriteTimeout: time.Duration(cfg.Server.WriteTimeout) * time.Second,
 	}
+
+	// Graceful shutdown
+	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
+	defer stop()
+
+	go func() {
+		logger.Log.Infow("server starting", "addr", srv.Addr)
+		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
+			logger.Log.Fatalw("listen failed", "error", err)
+		}
+	}()
+
+	<-ctx.Done()
+	logger.Log.Info("shutting down...")
+
+	shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	if err := srv.Shutdown(shutdownCtx); err != nil {
+		logger.Log.Errorw("shutdown error", "error", err)
+	}
+	logger.Log.Info("server stopped")
 }

 // healthHandler 健康检查。
-func healthHandler(c *gin.Context) {
-	c.JSON(200, gin.H{
-		"status":         "ok",
-		"version":        "0.1.0",
-		"uptime":         time.Since(startTime).String(),
-		"active_sessions": 0, // TODO: 接入 Session Manager
-	})
+func healthHandler(sessionMgr session.Manager) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		c.JSON(200, gin.H{
+			"status":          "ok",
+			"version":         "0.1.0",
+			"uptime_seconds":  int(time.Since(startTime).Seconds()),
+			"active_sessions": sessionMgr.ActiveCount(),
+		})
+	}
 }
--- a/backend/config.yaml
+++ b/backend/config.yaml
@@ -0,0 +1,39 @@
+# config.yaml — 默认配置
+app:
+  env: dev
+
+server:
+  host: "0.0.0.0"
+  port: 8080
+  read_timeout: 30
+  write_timeout: 30
+
+redis:
+  addr: "localhost:6379"
+  password: ""
+  db: 0
+
+ai:
+  stt:
+    provider: Xiaomi MiMo
+    model: mimo-v2.5
+    endpoint: "https://token-plan-cn.xiaomimimo.com/v1"
+  llm:
+    provider: dashscope
+    model: qwen3-vl-plus
+    endpoint: "https://dashscope.aliyuncs.com/compatible-mode/v1"
+    timeout: 30
+  tts:
+    provider: Xiaomi MiMo
+    model: mimo-v2.5
+    voice: alloy
+    speed: 1.0
+    endpoint: "https://token-plan-cn.xiaomimimo.com/v1"
+    timeout: 5
+
+storage:
+  driver: memory
+
+log:
+  level: info
+  format: console
--- a/backend/go.mod
+++ b/backend/go.mod
@@ -1,38 +1,58 @@
 module github.com/hhs/camtalk

-go 1.23
+go 1.24

 require (
 	github.com/gin-gonic/gin v1.10.0
 	github.com/google/uuid v1.6.0
 	github.com/gorilla/websocket v1.5.3
+	github.com/redis/go-redis/v9 v9.20.1
+	github.com/spf13/viper v1.21.0
+	github.com/stretchr/testify v1.11.1
+	go.uber.org/zap v1.28.0
 )

 require (
 	github.com/bytedance/sonic v1.11.6 // indirect
 	github.com/bytedance/sonic/loader v0.1.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/cloudwego/base64x v0.1.4 // indirect
 	github.com/cloudwego/iasm v0.2.0 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/fsnotify/fsnotify v1.9.0 // indirect
 	github.com/gabriel-vasile/mimetype v1.4.3 // indirect
 	github.com/gin-contrib/sse v0.1.0 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect
 	github.com/go-playground/universal-translator v0.18.1 // indirect
 	github.com/go-playground/validator/v10 v10.20.0 // indirect
+	github.com/go-viper/mapstructure/v2 v2.4.0 // indirect
 	github.com/goccy/go-json v0.10.2 // indirect
+	github.com/joho/godotenv v1.5.1 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
-	github.com/klauspost/cpuid/v2 v2.2.7 // indirect
+	github.com/klauspost/cpuid/v2 v2.2.10 // indirect
 	github.com/leodido/go-urn v1.4.0 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
-	github.com/pelletier/go-toml/v2 v2.2.2 // indirect
+	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/sagikazarmark/locafero v0.11.0 // indirect
+	github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 // indirect
+	github.com/spf13/afero v1.15.0 // indirect
+	github.com/spf13/cast v1.10.0 // indirect
+	github.com/spf13/pflag v1.0.10 // indirect
+	github.com/stretchr/objx v0.5.2 // indirect
+	github.com/subosito/gotenv v1.6.0 // indirect
 	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
 	github.com/ugorji/go/codec v1.2.12 // indirect
+	go.uber.org/atomic v1.11.0 // indirect
+	go.uber.org/multierr v1.10.0 // indirect
+	go.yaml.in/yaml/v3 v3.0.4 // indirect
 	golang.org/x/arch v0.8.0 // indirect
 	golang.org/x/crypto v0.23.0 // indirect
 	golang.org/x/net v0.25.0 // indirect
-	golang.org/x/sys v0.20.0 // indirect
-	golang.org/x/text v0.15.0 // indirect
+	golang.org/x/sys v0.30.0 // indirect
+	golang.org/x/text v0.28.0 // indirect
 	google.golang.org/protobuf v1.34.1 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
--- a/backend/go.sum
+++ b/backend/go.sum
@@ -1,7 +1,13 @@
+github.com/bsm/ginkgo/v2 v2.12.0 h1:Ny8MWAHyOepLGlLKYmXG4IEkioBysk6GpaRTLC8zwWs=
+github.com/bsm/ginkgo/v2 v2.12.0/go.mod h1:SwYbGRRDovPVboqFv0tPTcG1sN61LM1Z4ARdbAV9g4c=
+github.com/bsm/gomega v1.27.10 h1:yeMWxP2pV2fG3FgAODIY8EiRE3dy0aeFYt4l7wh6yKA=
+github.com/bsm/gomega v1.27.10/go.mod h1:JyEr/xRbxbtgWNi8tIEVPUYZ5Dzef52k01W3YH0H+O0=
 github.com/bytedance/sonic v1.11.6 h1:oUp34TzMlL+OY1OUWxHqsdkgC/Zfc85zGqw9siXjrc0=
 github.com/bytedance/sonic v1.11.6/go.mod h1:LysEHSvpvDySVdC2f87zGWf6CIKJcAvqab1ZaiQtds4=
 github.com/bytedance/sonic/loader v0.1.1 h1:c+e5Pt1k/cy5wMveRDyk2X4B9hF4g7an8N3zCYjJFNM=
 github.com/bytedance/sonic/loader v0.1.1/go.mod h1:ncP89zfokxS5LZrJxl5z0UJcsk4M4yY2JpfqGeCtNLU=
+github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
+github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/cloudwego/base64x v0.1.4 h1:jwCgWpFanWmN8xoIUHa2rtzmkd5J2plF/dnLS6Xd/0Y=
 github.com/cloudwego/base64x v0.1.4/go.mod h1:0zlkT4Wn5C6NdauXdJRhSKRlJvmclQ1hhJgA0rcu/8w=
 github.com/cloudwego/iasm v0.2.0 h1:1KNIy1I1H9hNNFEEH3DVnI4UujN+1zjpuk6gwHLTssg=
@@ -9,6 +15,10 @@ github.com/cloudwego/iasm v0.2.0/go.mod h1:8rXZaNYT2n95jn+zTI1sDr+IgcD2GVs0nlbbQ
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/frankban/quicktest v1.14.6 h1:7Xjx+VpznH+oBnejlPUj8oUpdxnVs4f8XU8WnHkI4W8=
+github.com/frankban/quicktest v1.14.6/go.mod h1:4ptaffx2x8+WTWXmUCuVU6aPUX1/Mz7zb5vbUoiM6w0=
+github.com/fsnotify/fsnotify v1.9.0 h1:2Ml+OJNzbYCTzsxtv8vKSFD9PbJjmhYF14k/jKC7S9k=
+github.com/fsnotify/fsnotify v1.9.0/go.mod h1:8jBTzvmWwFyi3Pb8djgCCO5IBqzKJ/Jwo8TRcHyHii0=
 github.com/gabriel-vasile/mimetype v1.4.3 h1:in2uUcidCuFcDKtdcBxlR0rJ1+fsokWf+uqxgUFjbI0=
 github.com/gabriel-vasile/mimetype v1.4.3/go.mod h1:d8uq/6HKRL6CGdk+aubisF/M5GcPfT7nKyLpA0lbSSk=
 github.com/gin-contrib/sse v0.1.0 h1:Y/yl/+YNO8GZSjAhjMsSuLt29uWRFHdHYUb5lYOV9qE=
@@ -23,21 +33,29 @@ github.com/go-playground/universal-translator v0.18.1 h1:Bcnm0ZwsGyWbCzImXv+pAJn
 github.com/go-playground/universal-translator v0.18.1/go.mod h1:xekY+UJKNuX9WP91TpwSH2VMlDf28Uj24BCp08ZFTUY=
 github.com/go-playground/validator/v10 v10.20.0 h1:K9ISHbSaI0lyB2eWMPJo+kOS/FBExVwjEviJTixqxL8=
 github.com/go-playground/validator/v10 v10.20.0/go.mod h1:dbuPbCMFw/DrkbEynArYaCwl3amGuJotoKCe95atGMM=
+github.com/go-viper/mapstructure/v2 v2.4.0 h1:EBsztssimR/CONLSZZ04E8qAkxNYq4Qp9LvH92wZUgs=
+github.com/go-viper/mapstructure/v2 v2.4.0/go.mod h1:oJDH3BJKyqBA2TXFhDsKDGDTlndYOZ6rGS0BRZIxGhM=
 github.com/goccy/go-json v0.10.2 h1:CrxCmQqYDkv1z7lO7Wbh2HN93uovUHgrECaO5ZrCXAU=
 github.com/goccy/go-json v0.10.2/go.mod h1:6MelG93GURQebXPDq3khkgXZkazVtN9CRI+MGFi0w8I=
-github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
-github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aNNg=
 github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
+github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
+github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
 github.com/json-iterator/go v1.1.12 h1:PV8peI4a0ysnczrg+LtxykD8LfKY9ML6u2jnxaEnrnM=
 github.com/json-iterator/go v1.1.12/go.mod h1:e30LSqwooZae/UwlEbR2852Gd8hjQvJoHmT4TnhNGBo=
 github.com/klauspost/cpuid/v2 v2.0.9/go.mod h1:FInQzS24/EEf25PyTYn52gqo7WaD8xa0213Md/qVLRg=
-github.com/klauspost/cpuid/v2 v2.2.7 h1:ZWSB3igEs+d0qvnxR/ZBzXVmxkgt8DdzP6m9pfuVLDM=
-github.com/klauspost/cpuid/v2 v2.2.7/go.mod h1:Lcz8mBdAVJIBVzewtcLocK12l3Y+JytZYpaMropDUws=
+github.com/klauspost/cpuid/v2 v2.2.10 h1:tBs3QSyvjDyFTq3uoc/9xFpCuOsJQFNPiAhYdw2skhE=
+github.com/klauspost/cpuid/v2 v2.2.10/go.mod h1:hqwkgyIinND0mEev00jJYCxPNVRVXFQeu1XKlok6oO0=
 github.com/knz/go-libedit v1.10.1/go.mod h1:MZTVkCWyz0oBc7JOWP3wNAzd002ZbM/5hgShxwh4x8M=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/leodido/go-urn v1.4.0 h1:WT9HwE9SGECu3lg4d/dIA+jxlljEa1/ffXKmRjqdmIQ=
 github.com/leodido/go-urn v1.4.0/go.mod h1:bvxc+MVxLKB4z00jd1z+Dvzr47oO32F/QSNjSBOlFxI=
 github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
@@ -47,26 +65,56 @@ github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd h1:TRLaZ9cD/w
 github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
 github.com/modern-go/reflect2 v1.0.2 h1:xBagoLtFs94CBntxluKeaWgTMpvLxC4ur3nMaC9Gz0M=
 github.com/modern-go/reflect2 v1.0.2/go.mod h1:yWuevngMOJpCy52FWWMvUC8ws7m/LJsjYzDa0/r8luk=
-github.com/pelletier/go-toml/v2 v2.2.2 h1:aYUidT7k73Pcl9nb2gScu7NSrKCSHIDE89b3+6Wq+LM=
-github.com/pelletier/go-toml/v2 v2.2.2/go.mod h1:1t835xjRzz80PqgE6HHgN2JOsmgYu/h4qDAS4n929Rs=
+github.com/pelletier/go-toml/v2 v2.2.4 h1:mye9XuhQ6gvn5h28+VilKrrPoQVanw5PMw/TB0t5Ec4=
+github.com/pelletier/go-toml/v2 v2.2.4/go.mod h1:2gIqNv+qfxSVS7cM2xJQKtLSTLUE9V8t9Stt+h56mCY=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/redis/go-redis/v9 v9.20.1 h1:sfCU6A8P3dXbKyWes02uxA2baehGux9dZHfEKtsTB1w=
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--- a/backend/internal/ai/llm/llm.go
+++ b/backend/internal/ai/llm/llm.go
@@ -0,0 +1,37 @@
+package llm
+
+import (
+	"context"
+
+	"github.com/hhs/camtalk/internal/models"
+)
+
+// Service 多模态大模型服务契约。
+type Service interface {
+	// ChatStream 流式推理，返回增量文本的 channel。
+	// 调用方必须消费 channel 直到 Done=true，否则需 cancel ctx 以释放连接。
+	ChatStream(ctx context.Context, req Request) (<-chan Chunk, error)
+}
+
+// Request 推理请求。
+type Request struct {
+	Image    []byte         // JPEG 图片（已从 Base64 解码）
+	Text     string         // 用户语音识别后的文本
+	History  []models.Message // 最近 N 轮对话历史
+	Language string         // 语言，如 "zh-CN"
+}
+
+// Chunk 流式推理的一个增量片段。
+type Chunk struct {
+	Delta      string       // 增量文本
+	Done       bool         // 是否结束
+	TokensUsed *TokenUsage  // 仅 Done=true 时有值
+	Model      string       // 实际使用的模型名
+}
+
+// TokenUsage 用量统计。
+type TokenUsage struct {
+	Prompt     int
+	Completion int
+	Total      int
+}
--- a/backend/internal/ai/llm/openai.go
+++ b/backend/internal/ai/llm/openai.go
@@ -0,0 +1,237 @@
+package llm
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"go.uber.org/zap"
+)
+
+// OpenAIService 基于 OpenAI Chat Completions API 的 LLM 实现。
+type OpenAIService struct {
+	apiKey   string
+	model    string
+	endpoint string
+	timeout  time.Duration
+	logger   *zap.SugaredLogger
+	client   *http.Client
+}
+
+// NewOpenAIService 创建 OpenAI LLM 服务。
+func NewOpenAIService(apiKey, model, endpoint string, timeoutSec int, logger *zap.SugaredLogger) *OpenAIService {
+	if model == "" {
+		model = "gpt-4o"
+	}
+	if endpoint == "" {
+		endpoint = "https://api.openai.com/v1"
+	}
+	timeout := time.Duration(timeoutSec) * time.Second
+	if timeout <= 0 {
+		timeout = 10 * time.Second
+	}
+	return &OpenAIService{
+		apiKey:   apiKey,
+		model:    model,
+		endpoint: endpoint,
+		timeout:  timeout,
+		logger:   logger,
+		client:   &http.Client{Timeout: 60 * time.Second}, // HTTP client timeout > LLM timeout
+	}
+}
+
+// --- OpenAI API 请求/响应结构 ---
+
+type chatRequest struct {
+	Model    string        `json:"model"`
+	Messages []chatMessage `json:"messages"`
+	Stream   bool          `json:"stream"`
+}
+
+type chatMessage struct {
+	Role    string        `json:"role"`
+	Content []contentPart `json:"content"`
+}
+
+type contentPart struct {
+	Type     string    `json:"type"`
+	Text     string    `json:"text,omitempty"`
+	ImageURL *imageURL `json:"image_url,omitempty"`
+}
+
+type imageURL struct {
+	URL string `json:"url"`
+}
+
+// streamDelta SSE 流式响应的单个 delta。
+type streamDelta struct {
+	Choices []struct {
+		Delta struct {
+			Content string `json:"content"`
+		} `json:"delta"`
+		FinishReason *string `json:"finish_reason"`
+	} `json:"choices"`
+	Usage *struct {
+		PromptTokens     int `json:"prompt_tokens"`
+		CompletionTokens int `json:"completion_tokens"`
+		TotalTokens      int `json:"total_tokens"`
+	} `json:"usage"`
+	Model string `json:"model"`
+}
+
+// ChatStream 实现 llm.Service。调用 OpenAI Chat Completions API 流式推理。
+func (o *OpenAIService) ChatStream(ctx context.Context, req Request) (<-chan Chunk, error) {
+	// 构建请求
+	messages := o.buildMessages(req)
+
+	body := chatRequest{
+		Model:    o.model,
+		Messages: messages,
+		Stream:   true,
+	}
+
+	payload, err := json.Marshal(body)
+	if err != nil {
+		return nil, fmt.Errorf("llm: marshal request: %w", err)
+	}
+
+	// 创建带超时的 context
+	ctx, cancel := context.WithTimeout(ctx, o.timeout)
+
+	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, o.endpoint+"/chat/completions", bytes.NewReader(payload))
+	if err != nil {
+		cancel()
+		return nil, fmt.Errorf("llm: create request: %w", err)
+	}
+	httpReq.Header.Set("Content-Type", "application/json")
+	httpReq.Header.Set("Authorization", "Bearer "+o.apiKey)
+
+	resp, err := o.client.Do(httpReq)
+	if err != nil {
+		cancel()
+		return nil, fmt.Errorf("llm: send request: %w", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		cancel()
+		bodyBytes, _ := io.ReadAll(resp.Body)
+		resp.Body.Close()
+		return nil, fmt.Errorf("llm: api error (status %d): %s", resp.StatusCode, string(bodyBytes))
+	}
+
+	// 启动 goroutine 解析 SSE 流
+	ch := make(chan Chunk, 64)
+	go func() {
+		defer close(ch)
+		defer cancel()
+		defer resp.Body.Close()
+
+		o.parseSSEStream(resp.Body, ch)
+	}()
+
+	return ch, nil
+}
+
+// parseSSEStream 解析 SSE 流，将 delta 发送到 channel。
+func (o *OpenAIService) parseSSEStream(body io.Reader, ch chan<- Chunk) {
+	scanner := bufio.NewScanner(body)
+	scanner.Buffer(make([]byte, 0, 64*1024), 256*1024)
+
+	var fullText strings.Builder
+	var lastModel string
+
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		// SSE 格式：data: {...}
+		if !strings.HasPrefix(line, "data: ") {
+			continue
+		}
+		data := strings.TrimPrefix(line, "data: ")
+		if data == "[DONE]" {
+			// 流结束，发送最终 chunk
+			ch <- Chunk{Delta: "", Done: true, Model: lastModel}
+			return
+		}
+
+		var delta streamDelta
+		if err := json.Unmarshal([]byte(data), &delta); err != nil {
+			o.logger.Warnw("llm: unmarshal delta failed", "error", err, "data", data)
+			continue
+		}
+
+		if delta.Model != "" {
+			lastModel = delta.Model
+		}
+
+		// 提取增量文本
+		if len(delta.Choices) > 0 {
+			content := delta.Choices[0].Delta.Content
+			if content != "" {
+				fullText.WriteString(content)
+				ch <- Chunk{Delta: content, Done: false, Model: lastModel}
+			}
+
+			// 某些模型在最后一个 choice 中携带 usage
+			if delta.Choices[0].FinishReason != nil && delta.Usage != nil {
+				ch <- Chunk{
+					Delta: "",
+					Done:  true,
+					Model: lastModel,
+					TokensUsed: &TokenUsage{
+						Prompt:     delta.Usage.PromptTokens,
+						Completion: delta.Usage.CompletionTokens,
+						Total:      delta.Usage.TotalTokens,
+					},
+				}
+				return
+			}
+		}
+	}
+
+	// scanner 结束但没收到 [DONE]
+	if err := scanner.Err(); err != nil {
+		o.logger.Warnw("llm: scan error", "error", err)
+	}
+	ch <- Chunk{Delta: "", Done: true, Model: lastModel}
+}
+
+// buildMessages 构建 OpenAI Chat API 的 messages 数组。
+func (o *OpenAIService) buildMessages(req Request) []chatMessage {
+	var messages []chatMessage
+
+	// System prompt
+	messages = append(messages, chatMessage{
+		Role:    "system",
+		Content: []contentPart{{Type: "text", Text: BuildSystemPrompt(req.Language, "")}},
+	})
+
+	// 历史消息
+	for _, msg := range req.History {
+		messages = append(messages, chatMessage{
+			Role:    msg.Role,
+			Content: []contentPart{{Type: "text", Text: msg.Content}},
+		})
+	}
+
+	// 当前用户消息（图像 + 文本）
+	var parts []contentPart
+	if len(req.Image) > 0 {
+		b64 := base64.StdEncoding.EncodeToString(req.Image)
+		parts = append(parts, contentPart{
+			Type:     "image_url",
+			ImageURL: &imageURL{URL: "data:image/jpeg;base64," + b64},
+		})
+	}
+	parts = append(parts, contentPart{Type: "text", Text: req.Text})
+	messages = append(messages, chatMessage{Role: "user", Content: parts})
+
+	return messages
+}
--- a/backend/internal/ai/llm/openai_test.go
+++ b/backend/internal/ai/llm/openai_test.go
@@ -0,0 +1,251 @@
+package llm
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+
+	"go.uber.org/zap"
+
+	"github.com/hhs/camtalk/internal/models"
+)
+
+// mockLLMServer 创建模拟 OpenAI SSE 流式响应的 HTTP 服务器。
+func mockLLMServer(t *testing.T, handler http.HandlerFunc) *httptest.Server {
+	t.Helper()
+	return httptest.NewServer(handler)
+}
+
+func TestOpenAIService_ChatStream_Success(t *testing.T) {
+	srv := mockLLMServer(t, func(w http.ResponseWriter, r *http.Request) {
+		// 验证请求
+		if r.Method != http.MethodPost {
+			t.Errorf("method = %s, want POST", r.Method)
+		}
+		if !strings.Contains(r.URL.Path, "/chat/completions") {
+			t.Errorf("path = %s, should contain /chat/completions", r.URL.Path)
+		}
+		auth := r.Header.Get("Authorization")
+		if auth != "Bearer test-key" {
+			t.Errorf("Authorization = %q, want %q", auth, "Bearer test-key")
+		}
+
+		w.Header().Set("Content-Type", "text/event-stream")
+		flusher, ok := w.(http.Flusher)
+		if !ok {
+			t.Fatal("ResponseWriter does not support Flusher")
+		}
+
+		// 发送几个 delta
+		deltas := []string{"你好", "世界", "！"}
+		for _, d := range deltas {
+			fmt.Fprintf(w, "data: {\"choices\":[{\"delta\":{\"content\":\"%s\"}}],\"model\":\"gpt-4o\"}\n\n", d)
+			flusher.Flush()
+		}
+
+		// 发送 [DONE]
+		fmt.Fprintf(w, "data: [DONE]\n\n")
+		flusher.Flush()
+	})
+	defer srv.Close()
+
+	svc := NewOpenAIService("test-key", "gpt-4o", srv.URL, 10, zap.NewNop().Sugar())
+
+	ch, err := svc.ChatStream(context.Background(), Request{
+		Text:     "这是什么？",
+		Language: "zh-CN",
+	})
+	if err != nil {
+		t.Fatalf("ChatStream() error: %v", err)
+	}
+
+	var chunks []Chunk
+	for c := range ch {
+		chunks = append(chunks, c)
+	}
+
+	// 应该有 3 个文本 chunk + 1 个 Done chunk
+	if len(chunks) != 4 {
+		t.Fatalf("got %d chunks, want 4", len(chunks))
+	}
+
+	// 验证文本内容
+	if chunks[0].Delta != "你好" {
+		t.Errorf("chunk[0].Delta = %q, want %q", chunks[0].Delta, "你好")
+	}
+	if chunks[1].Delta != "世界" {
+		t.Errorf("chunk[1].Delta = %q, want %q", chunks[1].Delta, "世界")
+	}
+
+	// 验证最后一个 chunk 是 Done
+	last := chunks[len(chunks)-1]
+	if !last.Done {
+		t.Error("last chunk should be Done")
+	}
+	if last.Model != "gpt-4o" {
+		t.Errorf("last chunk Model = %q, want %q", last.Model, "gpt-4o")
+	}
+}
+
+func TestOpenAIService_ChatStream_WithImage(t *testing.T) {
+	srv := mockLLMServer(t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/event-stream")
+		fmt.Fprintf(w, "data: {\"choices\":[{\"delta\":{\"content\":\"ok\"}}],\"model\":\"gpt-4o\"}\n\n")
+		fmt.Fprintf(w, "data: [DONE]\n\n")
+	})
+	defer srv.Close()
+
+	svc := NewOpenAIService("test-key", "gpt-4o", srv.URL, 10, zap.NewNop().Sugar())
+
+	ch, err := svc.ChatStream(context.Background(), Request{
+		Image:    []byte("fake-jpeg-data"),
+		Text:     "描述图片",
+		Language: "zh-CN",
+	})
+	if err != nil {
+		t.Fatalf("ChatStream() error: %v", err)
+	}
+
+	// 消费 channel
+	for range ch {
+	}
+}
+
+func TestOpenAIService_ChatStream_WithHistory(t *testing.T) {
+	srv := mockLLMServer(t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/event-stream")
+		fmt.Fprintf(w, "data: {\"choices\":[{\"delta\":{\"content\":\"ok\"}}],\"model\":\"gpt-4o\"}\n\n")
+		fmt.Fprintf(w, "data: [DONE]\n\n")
+	})
+	defer srv.Close()
+
+	svc := NewOpenAIService("test-key", "gpt-4o", srv.URL, 10, zap.NewNop().Sugar())
+
+	ch, err := svc.ChatStream(context.Background(), Request{
+		Text:     "继续",
+		Language: "zh-CN",
+		History: []models.Message{
+			{Role: "user", Content: "你好"},
+			{Role: "assistant", Content: "你好！有什么可以帮助你的吗？"},
+		},
+	})
+	if err != nil {
+		t.Fatalf("ChatStream() error: %v", err)
+	}
+
+	for range ch {
+	}
+}
+
+func TestOpenAIService_ChatStream_APIError(t *testing.T) {
+	srv := mockLLMServer(t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusUnauthorized)
+		fmt.Fprintf(w, `{"error":{"message":"Invalid API key"}}`)
+	})
+	defer srv.Close()
+
+	svc := NewOpenAIService("bad-key", "gpt-4o", srv.URL, 10, zap.NewNop().Sugar())
+
+	_, err := svc.ChatStream(context.Background(), Request{
+		Text: "test",
+	})
+	if err == nil {
+		t.Fatal("ChatStream() should return error for 401")
+	}
+	if !strings.Contains(err.Error(), "401") {
+		t.Errorf("error should mention 401, got: %v", err)
+	}
+}
+
+func TestOpenAIService_ChatStream_Timeout(t *testing.T) {
+	srv := mockLLMServer(t, func(w http.ResponseWriter, r *http.Request) {
+		// 模拟慢响应
+		time.Sleep(5 * time.Second)
+		w.Header().Set("Content-Type", "text/event-stream")
+		fmt.Fprintf(w, "data: {\"choices\":[{\"delta\":{\"content\":\"late\"}}]}\n\n")
+		fmt.Fprintf(w, "data: [DONE]\n\n")
+	})
+	defer srv.Close()
+
+	svc := NewOpenAIService("test-key", "gpt-4o", srv.URL, 1, zap.NewNop().Sugar()) // 1s timeout
+
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	ch, err := svc.ChatStream(ctx, Request{Text: "test"})
+	if err != nil {
+		// 超时可能在建立连接时或读取时发生
+		return
+	}
+
+	// 如果连接成功，消费 channel 应该超时
+	var gotContent bool
+	for c := range ch {
+		if c.Delta != "" {
+			gotContent = true
+		}
+	}
+	if gotContent {
+		t.Error("should not receive content before timeout")
+	}
+}
+
+func TestOpenAIService_ChatStream_UsageInResponse(t *testing.T) {
+	srv := mockLLMServer(t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/event-stream")
+		// 带 usage 的最后一个 chunk
+		fmt.Fprintf(w, "data: {\"choices\":[{\"delta\":{\"content\":\"hi\"},\"finish_reason\":\"stop\"}],\"model\":\"gpt-4o\",\"usage\":{\"prompt_tokens\":10,\"completion_tokens\":5,\"total_tokens\":15}}\n\n")
+		fmt.Fprintf(w, "data: [DONE]\n\n")
+	})
+	defer srv.Close()
+
+	svc := NewOpenAIService("test-key", "gpt-4o", srv.URL, 10, zap.NewNop().Sugar())
+
+	ch, err := svc.ChatStream(context.Background(), Request{Text: "test"})
+	if err != nil {
+		t.Fatalf("ChatStream() error: %v", err)
+	}
+
+	var last Chunk
+	for c := range ch {
+		last = c
+	}
+
+	if !last.Done {
+		t.Error("last chunk should be Done")
+	}
+	if last.TokensUsed == nil {
+		t.Fatal("last chunk should have TokensUsed")
+	}
+	if last.TokensUsed.Total != 15 {
+		t.Errorf("TokensUsed.Total = %d, want 15", last.TokensUsed.Total)
+	}
+}
+
+func TestBuildSystemPrompt(t *testing.T) {
+	tests := []struct {
+		name        string
+		language    string
+		detailLevel string
+		wantContain string
+	}{
+		{"chinese default", "zh-CN", "", "视觉助手"},
+		{"chinese high", "zh-CN", "high", "更详细"},
+		{"english default", "en", "", "visual assistant"},
+		{"english high", "en", "high", "detailed"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := BuildSystemPrompt(tt.language, tt.detailLevel)
+			if !strings.Contains(got, tt.wantContain) {
+				t.Errorf("BuildSystemPrompt(%q, %q) should contain %q", tt.language, tt.detailLevel, tt.wantContain)
+			}
+		})
+	}
+}
--- a/backend/internal/ai/llm/prompt.go
+++ b/backend/internal/ai/llm/prompt.go
@@ -0,0 +1,25 @@
+package llm
+
+import "strings"
+
+// BuildSystemPrompt 根据语言和细节级别构建系统提示词。
+func BuildSystemPrompt(language, detailLevel string) string {
+	isChinese := strings.HasPrefix(language, "zh")
+
+	var prompt strings.Builder
+	if isChinese {
+		prompt.WriteString("你是一个视觉助手。用户通过摄像头看到一个场景，并用语音向你提问。请用简洁自然的中文回答。如果涉及视觉描述，先说\"我看到……\"。回答控制在3-5句话以内，除非用户要求详细说明。")
+	} else {
+		prompt.WriteString("You are a visual assistant. The user sees a scene through their camera and asks questions by voice. Answer concisely and naturally. If describing visual content, start with 'I see...'. Keep answers to 3-5 sentences unless the user asks for detail.")
+	}
+
+	if detailLevel == "high" {
+		if isChinese {
+			prompt.WriteString("请提供更详细的视觉描述，包括颜色、位置、数量等细节。")
+		} else {
+			prompt.WriteString(" Provide detailed visual descriptions including colors, positions, quantities, and other details.")
+		}
+	}
+
+	return prompt.String()
+}
--- a/backend/internal/ai/stt/deepgram.go
+++ b/backend/internal/ai/stt/deepgram.go
@@ -0,0 +1,141 @@
+package stt
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	"github.com/gorilla/websocket"
+	"go.uber.org/zap"
+)
+
+// DeepgramService 基于 Deepgram WebSocket API 的语音识别实现。
+type DeepgramService struct {
+	apiKey   string
+	model    string
+	endpoint string
+	logger   *zap.SugaredLogger
+}
+
+// NewDeepgramService 创建 Deepgram STT 服务。
+func NewDeepgramService(apiKey, model, endpoint string, logger *zap.SugaredLogger) *DeepgramService {
+	if model == "" {
+		model = "nova-2"
+	}
+	if endpoint == "" {
+		endpoint = "wss://api.deepgram.com/v1/listen"
+	}
+	return &DeepgramService{
+		apiKey:   apiKey,
+		model:    model,
+		endpoint: endpoint,
+		logger:   logger,
+	}
+}
+
+// deepgramResponse Deepgram WebSocket 响应。
+type deepgramResponse struct {
+	Channel struct {
+		Alternatives []struct {
+			Transcript string  `json:"transcript"`
+			Confidence float64 `json:"confidence"`
+		} `json:"alternatives"`
+	} `json:"channel"`
+	IsFinal bool `json:"is_final"`
+}
+
+// Recognize 实现 stt.Service。通过 WebSocket 发送音频到 Deepgram，返回最终识别文本。
+func (d *DeepgramService) Recognize(ctx context.Context, audio []byte, opts Options) (string, error) {
+	if len(audio) == 0 {
+		return "", fmt.Errorf("stt: empty audio")
+	}
+
+	// 构建 WebSocket URL，附带查询参数
+	wsURL := d.buildURL(opts)
+
+	// 5 秒总超时
+	ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
+	defer cancel()
+
+	// 建立 WebSocket 连接
+	conn, _, err := websocket.DefaultDialer.DialContext(ctx, wsURL, http.Header{
+		"Authorization": []string{"Token " + d.apiKey},
+	})
+	if err != nil {
+		return "", fmt.Errorf("stt: connect deepgram: %w", err)
+	}
+	defer conn.Close()
+
+	// 发送音频数据（一次性）
+	if err := conn.WriteMessage(websocket.BinaryMessage, audio); err != nil {
+		return "", fmt.Errorf("stt: send audio: %w", err)
+	}
+
+	// 发送 Close 消息通知服务端音频已发送完毕
+	closeMsg := websocket.FormatCloseMessage(websocket.CloseNormalClosure, "")
+	_ = conn.WriteMessage(websocket.CloseMessage, closeMsg)
+
+	// 读取识别结果
+	var transcript strings.Builder
+	for {
+		_, message, err := conn.ReadMessage()
+		if err != nil {
+			// Close 帧是正常的结束信号
+			if websocket.IsCloseError(err, websocket.CloseNormalClosure) {
+				break
+			}
+			if websocket.IsUnexpectedCloseError(err, websocket.CloseNormalClosure) {
+				break
+			}
+			return "", fmt.Errorf("stt: read response: %w", err)
+		}
+
+		var resp deepgramResponse
+		if err := json.Unmarshal(message, &resp); err != nil {
+			d.logger.Warnw("stt: unmarshal response failed", "error", err)
+			continue
+		}
+
+		// 只累积 final 结果，跳过中间结果
+		if resp.IsFinal && len(resp.Channel.Alternatives) > 0 {
+			text := strings.TrimSpace(resp.Channel.Alternatives[0].Transcript)
+			if text != "" {
+				transcript.WriteString(text)
+			}
+		}
+	}
+
+	return strings.TrimSpace(transcript.String()), nil
+}
+
+// buildURL 构建 Deepgram WebSocket URL，包含音频格式参数。
+func (d *DeepgramService) buildURL(opts Options) string {
+	u, _ := url.Parse(d.endpoint)
+
+	encoding := opts.Encoding
+	if encoding == "" {
+		encoding = "pcm_s16le"
+	}
+	sampleRate := opts.SampleRate
+	if sampleRate == 0 {
+		sampleRate = 16000
+	}
+	language := opts.Language
+	if language == "" {
+		language = "zh-CN"
+	}
+
+	q := u.Query()
+	q.Set("encoding", encoding)
+	q.Set("sample_rate", fmt.Sprintf("%d", sampleRate))
+	q.Set("language", language)
+	q.Set("model", d.model)
+	q.Set("punctuate", "true")
+	u.RawQuery = q.Encode()
+
+	return u.String()
+}
--- a/backend/internal/ai/stt/deepgram_test.go
+++ b/backend/internal/ai/stt/deepgram_test.go
@@ -0,0 +1,191 @@
+package stt
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/gorilla/websocket"
+	"go.uber.org/zap"
+)
+
+var upgrader = websocket.Upgrader{
+	CheckOrigin: func(r *http.Request) bool { return true },
+}
+
+// newMockDeepgram 创建模拟 Deepgram WebSocket 服务。
+// 返回 httptest.Server 和对应的 ws:// URL。
+func newMockDeepgram(t *testing.T, handler func(conn *websocket.Conn)) *httptest.Server {
+	t.Helper()
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		conn, err := upgrader.Upgrade(w, r, nil)
+		if err != nil {
+			t.Logf("upgrade error: %v", err)
+			return
+		}
+		defer conn.Close()
+		handler(conn)
+	}))
+	return srv
+}
+
+// wsToWss 将 http:// 转换为 ws://。
+func wsToWss(httpURL string) string {
+	return "ws" + strings.TrimPrefix(httpURL, "http")
+}
+
+func TestDeepgramService_Recognize_Success(t *testing.T) {
+	srv := newMockDeepgram(t, func(conn *websocket.Conn) {
+		// 读取音频数据
+		_, _, err := conn.ReadMessage()
+		if err != nil {
+			t.Errorf("read audio: %v", err)
+			return
+		}
+
+		// 发送中间结果（非 final）
+		intermediate := deepgramResponse{
+			IsFinal: false,
+		}
+		intermediate.Channel.Alternatives = []struct {
+			Transcript string  `json:"transcript"`
+			Confidence float64 `json:"confidence"`
+		}{{Transcript: "你好", Confidence: 0.9}}
+		data, _ := json.Marshal(intermediate)
+		_ = conn.WriteMessage(websocket.TextMessage, data)
+
+		// 发送最终结果
+		final := deepgramResponse{
+			IsFinal: true,
+		}
+		final.Channel.Alternatives = []struct {
+			Transcript string  `json:"transcript"`
+			Confidence float64 `json:"confidence"`
+		}{{Transcript: "你好世界", Confidence: 0.95}}
+		data, _ = json.Marshal(final)
+		_ = conn.WriteMessage(websocket.TextMessage, data)
+
+		// 等待客户端关闭
+		_, _, _ = conn.ReadMessage()
+	})
+	defer srv.Close()
+
+	svc := NewDeepgramService("test-key", "", wsToWss(srv.URL)+"/v1/listen", zap.NewNop().Sugar())
+
+	text, err := svc.Recognize(context.Background(), []byte("fake-pcm-audio"), Options{
+		Encoding:   "pcm_s16le",
+		SampleRate: 16000,
+		Language:   "zh-CN",
+	})
+	if err != nil {
+		t.Fatalf("Recognize() error: %v", err)
+	}
+	if text != "你好世界" {
+		t.Errorf("Recognize() = %q, want %q", text, "你好世界")
+	}
+}
+
+func TestDeepgramService_Recognize_EmptyAudio(t *testing.T) {
+	svc := NewDeepgramService("test-key", "", "ws://localhost", zap.NewNop().Sugar())
+	_, err := svc.Recognize(context.Background(), nil, Options{})
+	if err == nil {
+		t.Fatal("Recognize() with empty audio should return error")
+	}
+}
+
+func TestDeepgramService_Recognize_ConnectError(t *testing.T) {
+	svc := NewDeepgramService("test-key", "", "ws://localhost:1", zap.NewNop().Sugar())
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	_, err := svc.Recognize(ctx, []byte("audio"), Options{})
+	if err == nil {
+		t.Fatal("Recognize() with bad endpoint should return error")
+	}
+}
+
+func TestDeepgramService_Recognize_Timeout(t *testing.T) {
+	// 模拟一个永不响应的服务端
+	srv := newMockDeepgram(t, func(conn *websocket.Conn) {
+		// 读取音频但不发送任何结果，让客户端超时
+		_, _, _ = conn.ReadMessage()
+		time.Sleep(10 * time.Second)
+	})
+	defer srv.Close()
+
+	svc := NewDeepgramService("test-key", "", wsToWss(srv.URL)+"/v1/listen", zap.NewNop().Sugar())
+
+	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+	defer cancel()
+
+	_, err := svc.Recognize(ctx, []byte("audio"), Options{})
+	if err == nil {
+		t.Fatal("Recognize() should timeout")
+	}
+}
+
+func TestDeepgramService_Recognize_MultipleFinals(t *testing.T) {
+	srv := newMockDeepgram(t, func(conn *websocket.Conn) {
+		_, _, _ = conn.ReadMessage()
+
+		// 发送多个 final 结果（多句话场景）
+		for _, text := range []string{"你好", "世界"} {
+			resp := deepgramResponse{IsFinal: true}
+			resp.Channel.Alternatives = []struct {
+				Transcript string  `json:"transcript"`
+				Confidence float64 `json:"confidence"`
+			}{{Transcript: text, Confidence: 0.9}}
+			data, _ := json.Marshal(resp)
+			_ = conn.WriteMessage(websocket.TextMessage, data)
+		}
+
+		_, _, _ = conn.ReadMessage()
+	})
+	defer srv.Close()
+
+	svc := NewDeepgramService("test-key", "", wsToWss(srv.URL)+"/v1/listen", zap.NewNop().Sugar())
+
+	text, err := svc.Recognize(context.Background(), []byte("audio"), Options{})
+	if err != nil {
+		t.Fatalf("Recognize() error: %v", err)
+	}
+	if text != "你好世界" {
+		t.Errorf("Recognize() = %q, want %q", text, "你好世界")
+	}
+}
+
+func TestDeepgramService_buildURL(t *testing.T) {
+	svc := NewDeepgramService("key", "", "wss://api.deepgram.com/v1/listen", zap.NewNop().Sugar())
+
+	tests := []struct {
+		name string
+		opts Options
+		want []string // URL 中应包含的参数
+	}{
+		{
+			name: "defaults",
+			opts: Options{},
+			want: []string{"encoding=pcm_s16le", "sample_rate=16000", "language=zh-CN"},
+		},
+		{
+			name: "custom",
+			opts: Options{Encoding: "wav", SampleRate: 44100, Language: "en"},
+			want: []string{"encoding=wav", "sample_rate=44100", "language=en"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			u := svc.buildURL(tt.opts)
+			for _, param := range tt.want {
+				if !strings.Contains(u, param) {
+					t.Errorf("buildURL() = %q, should contain %q", u, param)
+				}
+			}
+		})
+	}
+}
--- a/backend/internal/ai/stt/stt.go
+++ b/backend/internal/ai/stt/stt.go
@@ -0,0 +1,16 @@
+package stt
+
+import "context"
+
+// Service 语音识别服务契约。
+type Service interface {
+	// Recognize 识别一段完整音频，返回最终文本。
+	Recognize(ctx context.Context, audio []byte, opts Options) (string, error)
+}
+
+// Options 语音识别参数。
+type Options struct {
+	Encoding   string // 音频编码，如 "pcm_s16le"
+	SampleRate int    // 采样率，如 16000
+	Language   string // 语言，如 "zh-CN"
+}
--- a/backend/internal/ai/tts/openai.go
+++ b/backend/internal/ai/tts/openai.go
@@ -0,0 +1,154 @@
+package tts
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	"go.uber.org/zap"
+)
+
+// OpenAIService 基于 OpenAI TTS API 的语音合成实现。
+type OpenAIService struct {
+	apiKey   string
+	model    string
+	voice    string
+	speed    float64
+	endpoint string
+	timeout  time.Duration
+	logger   *zap.SugaredLogger
+	client   *http.Client
+}
+
+// NewOpenAIService 创建 OpenAI TTS 服务。
+func NewOpenAIService(apiKey, model, voice, endpoint string, speed float64, timeoutSec int, logger *zap.SugaredLogger) *OpenAIService {
+	if model == "" {
+		model = "tts-1"
+	}
+	if voice == "" {
+		voice = "alloy"
+	}
+	if speed <= 0 {
+		speed = 1.0
+	}
+	if endpoint == "" {
+		endpoint = "https://api.openai.com/v1"
+	}
+	timeout := time.Duration(timeoutSec) * time.Second
+	if timeout <= 0 {
+		timeout = 5 * time.Second
+	}
+	return &OpenAIService{
+		apiKey:   apiKey,
+		model:    model,
+		voice:    voice,
+		speed:    speed,
+		endpoint: endpoint,
+		timeout:  timeout,
+		logger:   logger,
+		client:   &http.Client{Timeout: 30 * time.Second},
+	}
+}
+
+// ttsRequest OpenAI TTS API 请求。
+type ttsRequest struct {
+	Model          string  `json:"model"`
+	Input          string  `json:"input"`
+	Voice          string  `json:"voice"`
+	ResponseFormat string  `json:"response_format"`
+	Speed          float64 `json:"speed"`
+}
+
+// SynthesizeStream 实现 tts.Service。从 textStream 读取句子，逐句调用 OpenAI TTS API。
+func (o *OpenAIService) SynthesizeStream(ctx context.Context, textStream <-chan string, opts Options) (<-chan Chunk, error) {
+	voice := opts.Voice
+	if voice == "" {
+		voice = o.voice
+	}
+	speed := opts.Speed
+	if speed <= 0 {
+		speed = o.speed
+	}
+
+	ch := make(chan Chunk, 4)
+	go func() {
+		defer close(ch)
+
+		for text := range textStream {
+			if text == "" {
+				continue
+			}
+
+			audio, err := o.synthesize(ctx, text, voice, speed)
+			if err != nil {
+				o.logger.Warnw("tts: synthesize failed", "error", err, "text", text)
+				// 静默跳过，不中断整个流
+				continue
+			}
+
+			select {
+			case ch <- Chunk{Audio: audio, IsLast: false}:
+			case <-ctx.Done():
+				return
+			}
+		}
+
+		// textStream 关闭，发送 IsLast 标记
+		select {
+		case ch <- Chunk{Audio: nil, IsLast: true}:
+		case <-ctx.Done():
+		}
+	}()
+
+	return ch, nil
+}
+
+// synthesize 调用 OpenAI TTS API 合成单个句子。
+func (o *OpenAIService) synthesize(ctx context.Context, text, voice string, speed float64) ([]byte, error) {
+	// 单句超时
+	ctx, cancel := context.WithTimeout(ctx, o.timeout)
+	defer cancel()
+
+	body := ttsRequest{
+		Model:          o.model,
+		Input:          text,
+		Voice:          voice,
+		ResponseFormat: "mp3",
+		Speed:          speed,
+	}
+
+	payload, err := json.Marshal(body)
+	if err != nil {
+		return nil, fmt.Errorf("tts: marshal request: %w", err)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, o.endpoint+"/audio/speech", bytes.NewReader(payload))
+	if err != nil {
+		return nil, fmt.Errorf("tts: create request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Authorization", "Bearer "+o.apiKey)
+
+	resp, err := o.client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("tts: send request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		errBody, _ := io.ReadAll(resp.Body)
+		return nil, fmt.Errorf("tts: api error (status %d): %s", resp.StatusCode, string(errBody))
+	}
+
+	// 读取整个 MP3 响应
+	audio, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("tts: read response: %w", err)
+	}
+
+	return audio, nil
+}
--- a/backend/internal/ai/tts/openai_test.go
+++ b/backend/internal/ai/tts/openai_test.go
@@ -0,0 +1,300 @@
+package tts
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"go.uber.org/zap"
+)
+
+// mockTTSServer 创建模拟 OpenAI TTS API 的 HTTP 服务器。
+func mockTTSServer(t *testing.T, handler http.HandlerFunc) *httptest.Server {
+	t.Helper()
+	return httptest.NewServer(handler)
+}
+
+// sendSentences 向 channel 发送句子并关闭。
+func sendSentences(sentences ...string) <-chan string {
+	ch := make(chan string, len(sentences))
+	for _, s := range sentences {
+		ch <- s
+	}
+	close(ch)
+	return ch
+}
+
+func TestOpenAIService_SynthesizeStream_Success(t *testing.T) {
+	var callCount int32
+	srv := mockTTSServer(t, func(w http.ResponseWriter, r *http.Request) {
+		atomic.AddInt32(&callCount, 1)
+
+		if r.Method != http.MethodPost {
+			t.Errorf("method = %s, want POST", r.Method)
+		}
+		if !strings.Contains(r.URL.Path, "/audio/speech") {
+			t.Errorf("path = %s, should contain /audio/speech", r.URL.Path)
+		}
+		auth := r.Header.Get("Authorization")
+		if auth != "Bearer test-key" {
+			t.Errorf("Authorization = %q, want %q", auth, "Bearer test-key")
+		}
+
+		// 验证请求体
+		body, _ := io.ReadAll(r.Body)
+		if !strings.Contains(string(body), "tts-1") {
+			t.Errorf("request body should contain model tts-1")
+		}
+
+		// 返回假 MP3 数据
+		w.Header().Set("Content-Type", "audio/mpeg")
+		fmt.Fprintf(w, "fake-mp3-data")
+	})
+	defer srv.Close()
+
+	svc := NewOpenAIService("test-key", "", "alloy", srv.URL, 1.0, 5, zap.NewNop().Sugar())
+
+	textStream := sendSentences("你好", "世界", "！")
+
+	ch, err := svc.SynthesizeStream(context.Background(), textStream, Options{
+		Voice: "alloy", Speed: 1.0, OutputFmt: "mp3", SampleRate: 24000,
+	})
+	if err != nil {
+		t.Fatalf("SynthesizeStream() error: %v", err)
+	}
+
+	var chunks []Chunk
+	for c := range ch {
+		chunks = append(chunks, c)
+	}
+
+	// 应该有 3 个音频 chunk + 1 个 IsLast 标记
+	if len(chunks) != 4 {
+		t.Fatalf("got %d chunks, want 4", len(chunks))
+	}
+
+	// 验证前 3 个有音频数据
+	for i := 0; i < 3; i++ {
+		if string(chunks[i].Audio) != "fake-mp3-data" {
+			t.Errorf("chunk[%d].Audio = %q, want %q", i, string(chunks[i].Audio), "fake-mp3-data")
+		}
+		if chunks[i].IsLast {
+			t.Errorf("chunk[%d].IsLast should be false", i)
+		}
+	}
+
+	// 验证最后一个是 IsLast
+	if !chunks[3].IsLast {
+		t.Error("last chunk should be IsLast")
+	}
+	if chunks[3].Audio != nil {
+		t.Error("last chunk Audio should be nil")
+	}
+
+	// 验证调用了 3 次 API（3 个句子）
+	if atomic.LoadInt32(&callCount) != 3 {
+		t.Errorf("API called %d times, want 3", callCount)
+	}
+}
+
+func TestOpenAIService_SynthesizeStream_APIError(t *testing.T) {
+	srv := mockTTSServer(t, func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusInternalServerError)
+		fmt.Fprintf(w, "internal error")
+	})
+	defer srv.Close()
+
+	svc := NewOpenAIService("test-key", "", "alloy", srv.URL, 1.0, 5, zap.NewNop().Sugar())
+
+	textStream := sendSentences("你好")
+
+	ch, err := svc.SynthesizeStream(context.Background(), textStream, Options{})
+	if err != nil {
+		t.Fatalf("SynthesizeStream() error: %v", err)
+	}
+
+	// 应该只有一个 IsLast chunk（音频被跳过）
+	var chunks []Chunk
+	for c := range ch {
+		chunks = append(chunks, c)
+	}
+
+	if len(chunks) != 1 {
+		t.Fatalf("got %d chunks, want 1 (IsLast only)", len(chunks))
+	}
+	if !chunks[0].IsLast {
+		t.Error("chunk should be IsLast")
+	}
+}
+
+func TestOpenAIService_SynthesizeStream_Timeout(t *testing.T) {
+	srv := mockTTSServer(t, func(w http.ResponseWriter, r *http.Request) {
+		time.Sleep(3 * time.Second)
+		w.Header().Set("Content-Type", "audio/mpeg")
+		fmt.Fprintf(w, "late-mp3")
+	})
+	defer srv.Close()
+
+	// 1 秒超时
+	svc := NewOpenAIService("test-key", "", "alloy", srv.URL, 1.0, 1, zap.NewNop().Sugar())
+
+	textStream := sendSentences("很长的句子")
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	ch, err := svc.SynthesizeStream(ctx, textStream, Options{})
+	if err != nil {
+		t.Fatalf("SynthesizeStream() error: %v", err)
+	}
+
+	var chunks []Chunk
+	for c := range ch {
+		chunks = append(chunks, c)
+	}
+
+	// 超时后音频被跳过，只有 IsLast
+	if len(chunks) != 1 {
+		t.Fatalf("got %d chunks, want 1", len(chunks))
+	}
+	if !chunks[0].IsLast {
+		t.Error("chunk should be IsLast")
+	}
+}
+
+func TestOpenAIService_SynthesizeStream_EmptyText(t *testing.T) {
+	var callCount int32
+	srv := mockTTSServer(t, func(w http.ResponseWriter, r *http.Request) {
+		atomic.AddInt32(&callCount, 1)
+		w.Header().Set("Content-Type", "audio/mpeg")
+		fmt.Fprintf(w, "mp3")
+	})
+	defer srv.Close()
+
+	svc := NewOpenAIService("test-key", "", "alloy", srv.URL, 1.0, 5, zap.NewNop().Sugar())
+
+	// 空句子应该被跳过
+	textStream := sendSentences("", "你好", "")
+
+	ch, err := svc.SynthesizeStream(context.Background(), textStream, Options{})
+	if err != nil {
+		t.Fatalf("SynthesizeStream() error: %v", err)
+	}
+
+	var chunks []Chunk
+	for c := range ch {
+		chunks = append(chunks, c)
+	}
+
+	// 只有 "你好" 应该被合成
+	if atomic.LoadInt32(&callCount) != 1 {
+		t.Errorf("API called %d times, want 1", callCount)
+	}
+
+	// 1 个音频 + 1 个 IsLast
+	if len(chunks) != 2 {
+		t.Fatalf("got %d chunks, want 2", len(chunks))
+	}
+}
+
+func TestOpenAIService_SynthesizeStream_ContextCancelled(t *testing.T) {
+	srv := mockTTSServer(t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "audio/mpeg")
+		fmt.Fprintf(w, "mp3")
+	})
+	defer srv.Close()
+
+	svc := NewOpenAIService("test-key", "", "alloy", srv.URL, 1.0, 5, zap.NewNop().Sugar())
+
+	// 发送多个句子，但在第一个后取消
+	textStream := make(chan string, 3)
+	textStream <- "第一句"
+	textStream <- "第二句"
+	textStream <- "第三句"
+	close(textStream)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	// 立即取消
+	cancel()
+
+	ch, err := svc.SynthesizeStream(ctx, textStream, Options{})
+	if err != nil {
+		t.Fatalf("SynthesizeStream() error: %v", err)
+	}
+
+	// 消费 channel，应该很快结束
+	var count int
+	for range ch {
+		count++
+	}
+	// 可能收到 0 个或 1 个 chunk，取决于时序
+	t.Logf("received %d chunks after context cancel", count)
+}
+
+func TestOpenAIService_SynthesizeStream_PartialFailure(t *testing.T) {
+	var callCount int32
+	srv := mockTTSServer(t, func(w http.ResponseWriter, r *http.Request) {
+		n := atomic.AddInt32(&callCount, 1)
+		if n == 2 {
+			// 第二个句子失败
+			w.WriteHeader(http.StatusInternalServerError)
+			fmt.Fprintf(w, "error")
+			return
+		}
+		w.Header().Set("Content-Type", "audio/mpeg")
+		fmt.Fprintf(w, "mp3-%d", n)
+	})
+	defer srv.Close()
+
+	svc := NewOpenAIService("test-key", "", "alloy", srv.URL, 1.0, 5, zap.NewNop().Sugar())
+
+	textStream := sendSentences("第一句", "第二句", "第三句")
+
+	ch, err := svc.SynthesizeStream(context.Background(), textStream, Options{})
+	if err != nil {
+		t.Fatalf("SynthesizeStream() error: %v", err)
+	}
+
+	var chunks []Chunk
+	for c := range ch {
+		chunks = append(chunks, c)
+	}
+
+	// 2 个成功音频 + 1 个 IsLast（第二句被跳过）
+	if len(chunks) != 3 {
+		t.Fatalf("got %d chunks, want 3", len(chunks))
+	}
+	if !chunks[len(chunks)-1].IsLast {
+		t.Error("last chunk should be IsLast")
+	}
+}
+
+func TestOpenAIService_SynthesizeStream_CustomVoice(t *testing.T) {
+	srv := mockTTSServer(t, func(w http.ResponseWriter, r *http.Request) {
+		body, _ := io.ReadAll(r.Body)
+		if !strings.Contains(string(body), "nova") {
+			t.Errorf("request body should contain voice 'nova', got: %s", string(body))
+		}
+		w.Header().Set("Content-Type", "audio/mpeg")
+		fmt.Fprintf(w, "mp3")
+	})
+	defer srv.Close()
+
+	svc := NewOpenAIService("test-key", "", "alloy", srv.URL, 1.0, 5, zap.NewNop().Sugar())
+
+	textStream := sendSentences("你好")
+
+	ch, err := svc.SynthesizeStream(context.Background(), textStream, Options{Voice: "nova"})
+	if err != nil {
+		t.Fatalf("SynthesizeStream() error: %v", err)
+	}
+
+	for range ch {
+	}
+}
--- a/backend/internal/ai/tts/tts.go
+++ b/backend/internal/ai/tts/tts.go
@@ -0,0 +1,25 @@
+package tts
+
+import "context"
+
+// Service 语音合成服务契约。
+type Service interface {
+	// SynthesizeStream 流式合成。
+	// textStream 接收句子级文本（由 Orchestrator 的句子切分器产出），
+	// 返回的 channel 持续输出 MP3 音频 chunk。
+	SynthesizeStream(ctx context.Context, textStream <-chan string, opts Options) (<-chan Chunk, error)
+}
+
+// Options 合成参数。
+type Options struct {
+	Voice      string  // "alloy" | "nova" | "shimmer" 等
+	Speed      float64 // 1.0 为正常语速
+	OutputFmt  string  // "mp3" — 固定使用 MP3
+	SampleRate int     // 24000
+}
+
+// Chunk 一个音频片段。
+type Chunk struct {
+	Audio  []byte // MP3 音频数据（未 Base64 编码）
+	IsLast bool   // 是否为最后一片
+}
--- a/backend/internal/api/session.go
+++ b/backend/internal/api/session.go
@@ -0,0 +1,91 @@
+// Package api 提供 REST API 处理函数。
+package api
+
+import (
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+
+	"github.com/hhs/camtalk/internal/models"
+	"github.com/hhs/camtalk/internal/session"
+)
+
+// SessionHandler 提供会话相关的 REST 端点。
+type SessionHandler struct {
+	sessionMgr session.Manager
+}
+
+// NewSessionHandler 创建 SessionHandler。
+func NewSessionHandler(sessionMgr session.Manager) *SessionHandler {
+	return &SessionHandler{sessionMgr: sessionMgr}
+}
+
+// CreateSessionRequest POST /api/sessions 请求体（所有字段可选）。
+type CreateSessionRequest struct {
+	Config *models.SessionConfig `json:"config,omitempty"`
+}
+
+// CreateSession POST /api/sessions — 创建新会话。
+func (h *SessionHandler) CreateSession(c *gin.Context) {
+	var req CreateSessionRequest
+	// 请求体可选，解析失败不报错（使用默认配置）
+	_ = c.ShouldBindJSON(&req)
+
+	cfg := models.DefaultConfig()
+	if req.Config != nil {
+		cfg = *req.Config
+	}
+
+	sessionID, err := h.sessionMgr.Create(c.Request.Context(), cfg)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{
+			"code":    "INTERNAL_ERROR",
+			"message": "failed to create session",
+		})
+		return
+	}
+
+	// 获取创建后的会话以返回 created_at
+	sess, err := h.sessionMgr.Get(c.Request.Context(), sessionID)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{
+			"code":    "INTERNAL_ERROR",
+			"message": "failed to retrieve created session",
+		})
+		return
+	}
+
+	c.JSON(http.StatusCreated, gin.H{
+		"session_id": sess.ID,
+		"created_at": sess.CreatedAt,
+	})
+}
+
+// DestroySession DELETE /api/sessions/:id — 销毁会话。
+func (h *SessionHandler) DestroySession(c *gin.Context) {
+	sessionID := c.Param("id")
+
+	err := h.sessionMgr.Destroy(c.Request.Context(), sessionID)
+	if err != nil {
+		if err == session.ErrSessionNotFound {
+			c.JSON(http.StatusNotFound, gin.H{
+				"code":    "SESSION_NOT_FOUND",
+				"message": "session not found or already expired",
+			})
+			return
+		}
+		c.JSON(http.StatusInternalServerError, gin.H{
+			"code":    "INTERNAL_ERROR",
+			"message": "failed to destroy session",
+		})
+		return
+	}
+
+	c.Status(http.StatusNoContent)
+}
+
+// RegisterRoutes 注册会话相关路由到给定的路由组。
+func (h *SessionHandler) RegisterRoutes(rg *gin.RouterGroup) {
+	rg.POST("/sessions", h.CreateSession)
+	rg.DELETE("/sessions/:id", h.DestroySession)
+}
--- a/backend/internal/config/config.go
+++ b/backend/internal/config/config.go
@@ -0,0 +1,160 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/joho/godotenv"
+	"github.com/spf13/viper"
+)
+
+// Config 应用配置。
+type Config struct {
+	App     AppConfig     `mapstructure:"app"`
+	Server  ServerConfig  `mapstructure:"server"`
+	Redis   RedisConfig   `mapstructure:"redis"`
+	AI      AIConfig      `mapstructure:"ai"`
+	Storage StorageConfig `mapstructure:"storage"`
+	Log     LogConfig     `mapstructure:"log"`
+}
+
+type AppConfig struct {
+	Env     string `mapstructure:"env"`
+	Version string `mapstructure:"version"`
+}
+
+type ServerConfig struct {
+	Host         string `mapstructure:"host"`
+	Port         int    `mapstructure:"port"`
+	ReadTimeout  int    `mapstructure:"read_timeout"`
+	WriteTimeout int    `mapstructure:"write_timeout"`
+}
+
+// Addr 返回 host:port 地址。
+func (s ServerConfig) Addr() string {
+	return fmt.Sprintf("%s:%d", s.Host, s.Port)
+}
+
+type RedisConfig struct {
+	Addr     string `mapstructure:"addr"`
+	Password string `mapstructure:"password"`
+	DB       int    `mapstructure:"db"`
+}
+
+type AIConfig struct {
+	STT STTConfig `mapstructure:"stt"`
+	LLM LLMConfig `mapstructure:"llm"`
+	TTS TTSConfig `mapstructure:"tts"`
+}
+
+type STTConfig struct {
+	Provider string `mapstructure:"provider"`
+	APIKey   string `mapstructure:"api_key"`
+	Model    string `mapstructure:"model"`
+	Endpoint string `mapstructure:"endpoint"`
+}
+
+type LLMConfig struct {
+	Provider string `mapstructure:"provider"`
+	APIKey   string `mapstructure:"api_key"`
+	Model    string `mapstructure:"model"`
+	Endpoint string `mapstructure:"endpoint"`
+	Timeout  int    `mapstructure:"timeout"`
+}
+
+type TTSConfig struct {
+	Provider string  `mapstructure:"provider"`
+	APIKey   string  `mapstructure:"api_key"`
+	Model    string  `mapstructure:"model"`
+	Voice    string  `mapstructure:"voice"`
+	Speed    float64 `mapstructure:"speed"`
+	Endpoint string  `mapstructure:"endpoint"`
+	Timeout  int     `mapstructure:"timeout"`
+}
+
+type StorageConfig struct {
+	Driver string `mapstructure:"driver"`
+	DSN    string `mapstructure:"dsn"`
+}
+
+type LogConfig struct {
+	Level  string `mapstructure:"level"`
+	Format string `mapstructure:"format"`
+}
+
+// Load 加载配置。优先级：环境变量 > config.{env}.yaml > config.yaml。
+func Load() (*Config, error) {
+	v := viper.New()
+	v.SetConfigName("config")
+	v.SetConfigType("yaml")
+	v.AddConfigPath(".")
+	v.AddConfigPath("./config")
+	v.AddConfigPath("./backend")
+
+	// 默认值
+	v.SetDefault("app.env", "dev")
+	v.SetDefault("server.host", "0.0.0.0")
+	v.SetDefault("server.port", 8080)
+	v.SetDefault("server.read_timeout", 30)
+	v.SetDefault("server.write_timeout", 30)
+	v.SetDefault("redis.addr", "localhost:6379")
+	v.SetDefault("redis.db", 0)
+	v.SetDefault("ai.stt.provider", "deepgram")
+	v.SetDefault("ai.stt.model", "nova-2")
+	v.SetDefault("ai.stt.endpoint", "wss://api.deepgram.com/v1/listen")
+	v.SetDefault("ai.llm.provider", "openai")
+	v.SetDefault("ai.llm.model", "gpt-4o")
+	v.SetDefault("ai.llm.endpoint", "https://api.openai.com/v1")
+	v.SetDefault("ai.llm.timeout", 10)
+	v.SetDefault("ai.tts.provider", "openai")
+	v.SetDefault("ai.tts.model", "tts-1")
+	v.SetDefault("ai.tts.voice", "alloy")
+	v.SetDefault("ai.tts.speed", 1.0)
+	v.SetDefault("ai.tts.endpoint", "https://api.openai.com/v1")
+	v.SetDefault("ai.tts.timeout", 5)
+	v.SetDefault("storage.driver", "memory")
+	v.SetDefault("log.level", "info")
+	v.SetDefault("log.format", "console")
+
+	// 读取基础配置文件
+	_ = v.ReadInConfig() // 文件不存在不报错
+
+	// 根据 APP_ENV 覆盖
+	env := os.Getenv("APP_ENV")
+	if env == "" {
+		env = v.GetString("app.env")
+	}
+	if env != "" {
+		v.SetConfigName("config." + env)
+		_ = v.MergeInConfig()
+	}
+
+	// 加载 .env 文件（不覆盖已有环境变量）
+	// 按优先级尝试：当前目录、上级目录（兼容从 backend/ 或项目根目录启动）
+	_ = godotenv.Load()
+	_ = godotenv.Load("../.env")
+
+	// 环境变量覆盖
+	v.SetEnvPrefix("CAMTALK")
+	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
+	v.AutomaticEnv()
+
+	var cfg Config
+	if err := v.Unmarshal(&cfg); err != nil {
+		return nil, fmt.Errorf("config unmarshal: %w", err)
+	}
+
+	// 填充默认值
+	if cfg.Server.Host == "" {
+		cfg.Server.Host = "0.0.0.0"
+	}
+	if cfg.Server.Port == 0 {
+		cfg.Server.Port = 8080
+	}
+	if cfg.App.Env == "" {
+		cfg.App.Env = "dev"
+	}
+
+	return &cfg, nil
+}
--- a/backend/internal/errors/codes.go
+++ b/backend/internal/errors/codes.go
@@ -0,0 +1,33 @@
+package errors
+
+import "github.com/hhs/camtalk/internal/models"
+
+// 错误码常量，与 docs/03-接口文档.md 保持一致。
+const (
+	CodeInvalidMessage  = "INVALID_MESSAGE"
+	CodeSessionNotFound = "SESSION_NOT_FOUND"
+	CodeRateLimited     = "RATE_LIMITED"
+	CodeImageTooLarge   = "IMAGE_TOO_LARGE"
+	CodeAudioTooShort   = "AUDIO_TOO_SHORT"
+	CodeLLMTimeout      = "LLM_TIMEOUT"
+	CodeLLMError        = "LLM_ERROR"
+	CodeSTTError        = "STT_ERROR"
+	CodeTTSError        = "TTS_ERROR"
+	CodeInternalError   = "INTERNAL_ERROR"
+)
+
+// Sender 定义发送 WS 错误消息的接口，便于测试 mock。
+type Sender interface {
+	SendError(code, requestID, message string)
+}
+
+// SendWSError 向客户端发送 error 消息。
+// sender 是一个具有 sendJSON 方法的对象，这里用接口抽象。
+func SendWSError(sender interface{ SendJSON(v any) error }, code, requestID string, err error) {
+	_ = sender.SendJSON(models.WsError{
+		Type:      "error",
+		Code:      code,
+		RequestID: requestID,
+		Message:   err.Error(),
+	})
+}
--- a/backend/internal/logger/logger.go
+++ b/backend/internal/logger/logger.go
@@ -0,0 +1,57 @@
+package logger
+
+import (
+	"os"
+
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+// Log 是全局 SugaredLogger，由 Init 初始化。
+var Log *zap.SugaredLogger
+
+// Init 初始化全局日志器。
+// level: "debug", "info", "warn", "error"
+// format: "json" 或 "console"
+func Init(level, format string) {
+	var lvl zapcore.Level
+	switch level {
+	case "debug":
+		lvl = zapcore.DebugLevel
+	case "warn":
+		lvl = zapcore.WarnLevel
+	case "error":
+		lvl = zapcore.ErrorLevel
+	default:
+		lvl = zapcore.InfoLevel
+	}
+
+	encoderCfg := zap.NewProductionEncoderConfig()
+	encoderCfg.TimeKey = "ts"
+	encoderCfg.EncodeTime = zapcore.ISO8601TimeEncoder
+
+	var core zapcore.Core
+	if format == "console" {
+		core = zapcore.NewCore(
+			zapcore.NewConsoleEncoder(encoderCfg),
+			zapcore.AddSync(os.Stdout),
+			lvl,
+		)
+	} else {
+		core = zapcore.NewCore(
+			zapcore.NewJSONEncoder(encoderCfg),
+			zapcore.AddSync(os.Stdout),
+			lvl,
+		)
+	}
+
+	logger := zap.New(core, zap.AddCaller(), zap.AddStacktrace(zapcore.ErrorLevel))
+	Log = logger.Sugar()
+}
+
+// Sync 刷新缓冲区，退出前调用。
+func Sync() {
+	if Log != nil {
+		_ = Log.Sync()
+	}
+}
--- a/backend/internal/models/models.go
+++ b/backend/internal/models/models.go
@@ -21,6 +21,26 @@ func DefaultConfig() SessionConfig {
 	return SessionConfig{TTSEnabled: true, DetailLevel: "low", Language: "zh-CN"}
 }

+// SessionConfigPatch 会话配置增量更新（指针字段表示"未传则不更新"）。
+type SessionConfigPatch struct {
+	TTSEnabled  *bool   `json:"tts_enabled,omitempty"`
+	DetailLevel *string `json:"detail_level,omitempty"`
+	Language    *string `json:"language,omitempty"`
+}
+
+// Apply 将 patch 中的非 nil 字段覆盖到 cfg。
+func (p SessionConfigPatch) Apply(cfg *SessionConfig) {
+	if p.TTSEnabled != nil {
+		cfg.TTSEnabled = *p.TTSEnabled
+	}
+	if p.DetailLevel != nil {
+		cfg.DetailLevel = *p.DetailLevel
+	}
+	if p.Language != nil {
+		cfg.Language = *p.Language
+	}
+}
+
 // Message 对话消息。
 type Message struct {
 	Role    string `json:"role"` // "user" | "assistant"
--- a/backend/internal/orchestrator/orchestrator.go
+++ b/backend/internal/orchestrator/orchestrator.go
@@ -0,0 +1,33 @@
+// Package orchestrator 实现 STT → LLM → TTS 流式并行管道。
+package orchestrator
+
+import (
+	"context"
+
+	"github.com/hhs/camtalk/internal/models"
+)
+
+// Orchestrator AI 编排器接口。
+// 接收查询并执行完整的 STT → LLM → TTS 管道。
+type Orchestrator interface {
+	// ProcessQuery 处理一次用户查询。
+	// ctx 用于整体超时和中断控制。
+	// sessionID 用于会话管理和历史获取。
+	// req 包含图像和音频数据。
+	// history 是最近的对话历史。
+	// sender 用于向客户端推送消息。
+	ProcessQuery(
+		ctx context.Context,
+		sessionID string,
+		req models.WsQuery,
+		history []models.Message,
+		sender Sender,
+	) error
+}
+
+// QueryRequest 查询请求（内部使用）。
+type QueryRequest struct {
+	Image    []byte // JPEG 图片（已从 Base64 解码）
+	Audio    []byte // 音频数据（已从 Base64 解码）
+	Language string // 语言，如 "zh-CN"
+}
--- a/backend/internal/orchestrator/pipeline.go
+++ b/backend/internal/orchestrator/pipeline.go
@@ -0,0 +1,328 @@
+package orchestrator
+
+import (
+	"context"
+	"encoding/base64"
+	"strings"
+	"sync"
+	"time"
+	"unicode/utf8"
+
+	"github.com/hhs/camtalk/internal/ai/llm"
+	"github.com/hhs/camtalk/internal/ai/stt"
+	"github.com/hhs/camtalk/internal/ai/tts"
+	"github.com/hhs/camtalk/internal/logger"
+	"github.com/hhs/camtalk/internal/models"
+	"github.com/hhs/camtalk/internal/session"
+)
+
+// Pipeline 实现 Orchestrator 接口，管理 STT → LLM → TTS 流式管道。
+type Pipeline struct {
+	sttService stt.Service
+	llmService llm.Service
+	ttsService tts.Service
+	sessionMgr session.Manager
+	model      string // LLM 模型名，用于 llm_done 上报
+}
+
+// New 创建 Pipeline 实例。
+func New(
+	sttService stt.Service,
+	llmService llm.Service,
+	ttsService tts.Service,
+	sessionMgr session.Manager,
+	model string,
+) *Pipeline {
+	return &Pipeline{
+		sttService: sttService,
+		llmService: llmService,
+		ttsService: ttsService,
+		sessionMgr: sessionMgr,
+		model:      model,
+	}
+}
+
+// ProcessQuery 实现 Orchestrator 接口。
+func (p *Pipeline) ProcessQuery(
+	ctx context.Context,
+	sessionID string,
+	req models.WsQuery,
+	history []models.Message,
+	sender Sender,
+) error {
+	log := logger.Log
+	startTime := time.Now()
+
+	// 解码音频数据
+	audio, err := base64.StdEncoding.DecodeString(req.Audio)
+	if err != nil {
+		log.Errorw("音频解码失败", "error", err)
+		sender.SendError(models.WsError{
+			Type:      "error",
+			RequestID: req.RequestID,
+			Code:      "INVALID_MESSAGE",
+			Message:   "音频数据解码失败",
+		})
+		return err
+	}
+
+	// 解码图片数据（可选）
+	var image []byte
+	if req.Image != "" {
+		image, err = base64.StdEncoding.DecodeString(req.Image)
+		if err != nil {
+			log.Errorw("图片解码失败", "error", err)
+			sender.SendError(models.WsError{
+				Type:      "error",
+				RequestID: req.RequestID,
+				Code:      "INVALID_MESSAGE",
+				Message:   "图片数据解码失败",
+			})
+			return err
+		}
+	}
+
+	// 设置活跃请求
+	if err := p.sessionMgr.SetActiveRequest(ctx, sessionID, req.RequestID); err != nil {
+		log.Errorw("设置活跃请求失败", "error", err)
+	}
+	defer p.sessionMgr.ClearActiveRequest(ctx, sessionID)
+
+	// 获取会话配置
+	sess, err := p.sessionMgr.Get(ctx, sessionID)
+	if err != nil {
+		log.Errorw("获取会话失败", "error", err)
+		sender.SendError(models.WsError{
+			Type:      "error",
+			RequestID: req.RequestID,
+			Code:      "SESSION_NOT_FOUND",
+			Message:   "会话不存在",
+		})
+		return err
+	}
+
+	// Step 1: STT 语音识别
+	log.Infow("开始语音识别", "request_id", req.RequestID)
+	sttResult, err := p.sttService.Recognize(ctx, audio, stt.Options{
+		Encoding:   "pcm_s16le",
+		SampleRate: 16000,
+		Language:   sess.Config.Language,
+	})
+	if err != nil {
+		log.Errorw("语音识别失败", "error", err)
+		sender.SendError(models.WsError{
+			Type:      "error",
+			RequestID: req.RequestID,
+			Code:      "STT_ERROR",
+			Message:   "语音识别失败",
+		})
+		return err
+	}
+
+	// 发送 STT 结果
+	if err := sender.SendSTTResult(models.WsSTTResult{
+		Type:      "stt_result",
+		RequestID: req.RequestID,
+		Text:      sttResult,
+		IsFinal:   true,
+	}); err != nil {
+		log.Errorw("发送 STT 结果失败", "error", err)
+	}
+
+	// 追加用户消息到历史
+	p.sessionMgr.AppendMessage(ctx, sessionID, models.Message{
+		Role:    "user",
+		Content: sttResult,
+	})
+
+	// Step 2+3: LLM 流式推理 + TTS 并行合成
+	log.Infow("开始 LLM 推理", "request_id", req.RequestID)
+	llmReq := llm.Request{
+		Image:    image,
+		Text:     sttResult,
+		History:  history,
+		Language: sess.Config.Language,
+	}
+
+	llmStream, err := p.llmService.ChatStream(ctx, llmReq)
+	if err != nil {
+		log.Errorw("LLM 流式推理启动失败", "error", err)
+		sender.SendError(models.WsError{
+			Type:      "error",
+			RequestID: req.RequestID,
+			Code:      "LLM_ERROR",
+			Message:   "LLM 推理失败",
+		})
+		return err
+	}
+
+	// 创建句子切分器
+	sentenceCh := make(chan string, 4)
+	splitter := NewSplitter(sentenceCh)
+
+	// 并行：LLM 消费 + TTS 合成
+	var wg sync.WaitGroup
+	var fullText string
+	var ttsErr error
+
+	// goroutine 1: 消费 LLM token + 句子切分
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		defer close(sentenceCh)
+		fullText = p.consumeLLMStream(ctx, llmStream, req.RequestID, sender, splitter)
+	}()
+
+	// goroutine 2: TTS 合成（如果启用）
+	if sess.Config.TTSEnabled {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			log.Infow("开始 TTS 合成", "request_id", req.RequestID)
+			ttsErr = p.synthesizeTTS(ctx, sentenceCh, req.RequestID, sender)
+		}()
+	} else {
+		// 如果 TTS 未启用，需要消费 sentenceCh 防止阻塞
+		go func() {
+			for range sentenceCh {
+			}
+		}()
+	}
+
+	// 等待所有 goroutine 完成
+	wg.Wait()
+
+	// TTS 失败静默跳过
+	if ttsErr != nil {
+		log.Warnw("TTS 合成失败（已跳过）", "error", ttsErr)
+	}
+
+	// 追加助手消息到历史
+	p.sessionMgr.AppendMessage(ctx, sessionID, models.Message{
+		Role:    "assistant",
+		Content: fullText,
+	})
+
+	// 发送 llm_done
+	latency := time.Since(startTime).Milliseconds()
+	if err := sender.SendLLMDone(models.WsLLMDone{
+		Type:      "llm_done",
+		RequestID: req.RequestID,
+		FullText:  fullText,
+		Model:     p.model,
+		LatencyMs: latency,
+	}); err != nil {
+		log.Errorw("发送 llm_done 失败", "error", err)
+	}
+
+	log.Infow("查询处理完成",
+		"request_id", req.RequestID,
+		"latency_ms", latency,
+		"text_length", utf8.RuneCountInString(fullText),
+	)
+
+	return nil
+}
+
+// consumeLLMStream 消费 LLM 流式输出，发送 llm_chunk 并进行句子切分。
+func (p *Pipeline) consumeLLMStream(
+	ctx context.Context,
+	stream <-chan llm.Chunk,
+	requestID string,
+	sender Sender,
+	splitter *Splitter,
+) string {
+	log := logger.Log
+	var fullText strings.Builder
+
+	for chunk := range stream {
+		// 检查上下文是否已取消
+		select {
+		case <-ctx.Done():
+			log.Infow("LLM 流被中断", "request_id", requestID)
+			return fullText.String()
+		default:
+		}
+
+		if chunk.Done {
+			// 流结束
+			if chunk.TokensUsed != nil {
+				log.Infow("LLM 用量统计",
+					"request_id", requestID,
+					"prompt_tokens", chunk.TokensUsed.Prompt,
+					"completion_tokens", chunk.TokensUsed.Completion,
+					"total_tokens", chunk.TokensUsed.Total,
+				)
+			}
+			break
+		}
+
+		// 累积全文
+		fullText.WriteString(chunk.Delta)
+
+		// 发送 llm_chunk
+		if err := sender.SendLLMChunk(models.WsLLMChunk{
+			Type:      "llm_chunk",
+			RequestID: requestID,
+			Delta:     chunk.Delta,
+			Role:      "assistant",
+		}); err != nil {
+			log.Errorw("发送 llm_chunk 失败", "error", err)
+		}
+
+		// 句子切分
+		splitter.Feed(chunk.Delta)
+	}
+
+	// 刷新切分器中的剩余文本
+	splitter.Flush()
+
+	return fullText.String()
+}
+
+// synthesizeTTS 从句子 channel 读取文本，进行 TTS 合成并发送音频。
+func (p *Pipeline) synthesizeTTS(
+	ctx context.Context,
+	sentenceCh <-chan string,
+	requestID string,
+	sender Sender,
+) error {
+	log := logger.Log
+
+	ttsStream, err := p.ttsService.SynthesizeStream(ctx, sentenceCh, tts.Options{
+		Voice:      "alloy",
+		Speed:      1.0,
+		OutputFmt:  "mp3",
+		SampleRate: 24000,
+	})
+	if err != nil {
+		log.Errorw("TTS 合成启动失败", "error", err)
+		return err
+	}
+
+	// 消费 TTS 音频流
+	for chunk := range ttsStream {
+		// 检查上下文是否已取消
+		select {
+		case <-ctx.Done():
+			log.Infow("TTS 流被中断", "request_id", requestID)
+			return ctx.Err()
+		default:
+		}
+
+		// Base64 编码音频数据
+		audioBase64 := base64.StdEncoding.EncodeToString(chunk.Audio)
+
+		if err := sender.SendTTSAudio(models.WsTTSAudio{
+			Type:      "tts_audio",
+			RequestID: requestID,
+			Audio:     audioBase64,
+			MimeType:  "audio/mp3",
+			IsLast:    chunk.IsLast,
+		}); err != nil {
+			log.Errorw("发送 tts_audio 失败", "error", err)
+		}
+	}
+
+	return nil
+}
--- a/backend/internal/orchestrator/pipeline_test.go
+++ b/backend/internal/orchestrator/pipeline_test.go
@@ -0,0 +1,661 @@
+package orchestrator
+
+import (
+	"context"
+	"encoding/base64"
+	"errors"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+
+	"github.com/hhs/camtalk/internal/ai/llm"
+	"github.com/hhs/camtalk/internal/ai/stt"
+	"github.com/hhs/camtalk/internal/ai/tts"
+	"github.com/hhs/camtalk/internal/logger"
+	"github.com/hhs/camtalk/internal/models"
+)
+
+func init() {
+	logger.Init("debug", "console")
+}
+
+// MockSTTService mock STT 服务
+type MockSTTService struct {
+	mock.Mock
+}
+
+func (m *MockSTTService) Recognize(ctx context.Context, audio []byte, opts stt.Options) (string, error) {
+	args := m.Called(ctx, audio, opts)
+	return args.String(0), args.Error(1)
+}
+
+// MockLLMService mock LLM 服务
+type MockLLMService struct {
+	mock.Mock
+}
+
+func (m *MockLLMService) ChatStream(ctx context.Context, req llm.Request) (<-chan llm.Chunk, error) {
+	args := m.Called(ctx, req)
+	if args.Get(0) == nil {
+		return nil, args.Error(1)
+	}
+	return args.Get(0).(<-chan llm.Chunk), args.Error(1)
+}
+
+// MockTTSService mock TTS 服务
+type MockTTSService struct {
+	mock.Mock
+}
+
+func (m *MockTTSService) SynthesizeStream(ctx context.Context, textStream <-chan string, opts tts.Options) (<-chan tts.Chunk, error) {
+	args := m.Called(ctx, textStream, opts)
+	if args.Get(0) == nil {
+		return nil, args.Error(1)
+	}
+	return args.Get(0).(<-chan tts.Chunk), args.Error(1)
+}
+
+// MockSessionManager mock 会话管理器
+type MockSessionManager struct {
+	mock.Mock
+}
+
+func (m *MockSessionManager) Create(ctx context.Context, config models.SessionConfig) (string, error) {
+	args := m.Called(ctx, config)
+	return args.String(0), args.Error(1)
+}
+
+func (m *MockSessionManager) Get(ctx context.Context, sessionID string) (*models.Session, error) {
+	args := m.Called(ctx, sessionID)
+	if args.Get(0) == nil {
+		return nil, args.Error(1)
+	}
+	return args.Get(0).(*models.Session), args.Error(1)
+}
+
+func (m *MockSessionManager) UpdateConfig(ctx context.Context, sessionID string, patch models.SessionConfigPatch) error {
+	args := m.Called(ctx, sessionID, patch)
+	return args.Error(0)
+}
+
+func (m *MockSessionManager) GetHistory(ctx context.Context, sessionID string, limit int) ([]models.Message, error) {
+	args := m.Called(ctx, sessionID, limit)
+	return args.Get(0).([]models.Message), args.Error(1)
+}
+
+func (m *MockSessionManager) AppendMessage(ctx context.Context, sessionID string, msg models.Message) error {
+	args := m.Called(ctx, sessionID, msg)
+	return args.Error(0)
+}
+
+func (m *MockSessionManager) SetActiveRequest(ctx context.Context, sessionID string, requestID string) error {
+	args := m.Called(ctx, sessionID, requestID)
+	return args.Error(0)
+}
+
+func (m *MockSessionManager) GetActiveRequestID(ctx context.Context, sessionID string) (string, error) {
+	args := m.Called(ctx, sessionID)
+	return args.String(0), args.Error(1)
+}
+
+func (m *MockSessionManager) ClearActiveRequest(ctx context.Context, sessionID string) error {
+	args := m.Called(ctx, sessionID)
+	return args.Error(0)
+}
+
+func (m *MockSessionManager) Touch(ctx context.Context, sessionID string) error {
+	args := m.Called(ctx, sessionID)
+	return args.Error(0)
+}
+
+func (m *MockSessionManager) Destroy(ctx context.Context, sessionID string) error {
+	args := m.Called(ctx, sessionID)
+	return args.Error(0)
+}
+
+func (m *MockSessionManager) ActiveCount() int {
+	args := m.Called()
+	return args.Int(0)
+}
+
+// MockSender mock WebSocket 发送器
+type MockSender struct {
+	mock.Mock
+	STTResults  []models.WsSTTResult
+	LLMChunks   []models.WsLLMChunk
+	LLMDones    []models.WsLLMDone
+	TTSAudios   []models.WsTTSAudio
+	Errors      []models.WsError
+}
+
+func NewMockSender() *MockSender {
+	return &MockSender{
+		STTResults: make([]models.WsSTTResult, 0),
+		LLMChunks:  make([]models.WsLLMChunk, 0),
+		LLMDones:   make([]models.WsLLMDone, 0),
+		TTSAudios:  make([]models.WsTTSAudio, 0),
+		Errors:     make([]models.WsError, 0),
+	}
+}
+
+func (m *MockSender) SendSTTResult(result models.WsSTTResult) error {
+	m.STTResults = append(m.STTResults, result)
+	args := m.Called(result)
+	return args.Error(0)
+}
+
+func (m *MockSender) SendLLMChunk(chunk models.WsLLMChunk) error {
+	m.LLMChunks = append(m.LLMChunks, chunk)
+	args := m.Called(chunk)
+	return args.Error(0)
+}
+
+func (m *MockSender) SendLLMDone(done models.WsLLMDone) error {
+	m.LLMDones = append(m.LLMDones, done)
+	args := m.Called(done)
+	return args.Error(0)
+}
+
+func (m *MockSender) SendTTSAudio(audio models.WsTTSAudio) error {
+	m.TTSAudios = append(m.TTSAudios, audio)
+	args := m.Called(audio)
+	return args.Error(0)
+}
+
+func (m *MockSender) SendError(err models.WsError) error {
+	m.Errors = append(m.Errors, err)
+	args := m.Called(err)
+	return args.Error(0)
+}
+
+// 辅助函数：创建 LLM 流式响应
+func createLLMStream(chunks []llm.Chunk) <-chan llm.Chunk {
+	ch := make(chan llm.Chunk, len(chunks))
+	for _, chunk := range chunks {
+		ch <- chunk
+	}
+	close(ch)
+	return ch
+}
+
+// 辅助函数：创建 TTS 流式响应
+func createTTSStream(chunks []tts.Chunk) <-chan tts.Chunk {
+	ch := make(chan tts.Chunk, len(chunks))
+	for _, chunk := range chunks {
+		ch <- chunk
+	}
+	close(ch)
+	return ch
+}
+
+// TestProcessQuery_Success 测试完整流程
+func TestProcessQuery_Success(t *testing.T) {
+	// 准备测试数据
+	audioData := []byte("test audio")
+	imageData := []byte("test image")
+	audioBase64 := base64.StdEncoding.EncodeToString(audioData)
+	imageBase64 := base64.StdEncoding.EncodeToString(imageData)
+
+	req := models.WsQuery{
+		Type:      "query",
+		RequestID: "req-123",
+		Image:     imageBase64,
+		Audio:     audioBase64,
+	}
+
+	session := &models.Session{
+		ID: "session-123",
+		Config: models.SessionConfig{
+			TTSEnabled:  true,
+			DetailLevel: "low",
+			Language:    "zh-CN",
+		},
+	}
+
+	// 创建 mock
+	mockSTT := new(MockSTTService)
+	mockLLM := new(MockLLMService)
+	mockTTS := new(MockTTSService)
+	mockSession := new(MockSessionManager)
+	mockSender := NewMockSender()
+
+	// 设置 mock 期望
+	mockSession.On("SetActiveRequest", mock.Anything, "session-123", "req-123").Return(nil)
+	mockSession.On("ClearActiveRequest", mock.Anything, "session-123").Return(nil)
+	mockSession.On("Get", mock.Anything, "session-123").Return(session, nil)
+	mockSession.On("AppendMessage", mock.Anything, "session-123", mock.Anything).Return(nil)
+
+	mockSTT.On("Recognize", mock.Anything, audioData, stt.Options{
+		Encoding:   "pcm_s16le",
+		SampleRate: 16000,
+		Language:   "zh-CN",
+	}).Return("你好，世界", nil)
+
+	mockSender.On("SendSTTResult", mock.Anything).Return(nil)
+
+	llmChunks := []llm.Chunk{
+		{Delta: "你好"},
+		{Delta: "，世界！"},
+		{Done: true, TokensUsed: &llm.TokenUsage{Prompt: 10, Completion: 5, Total: 15}},
+	}
+	mockLLM.On("ChatStream", mock.Anything, mock.Anything).Return(createLLMStream(llmChunks), nil)
+
+	mockSender.On("SendLLMChunk", mock.Anything).Return(nil)
+	mockSender.On("SendLLMDone", mock.Anything).Return(nil)
+
+	ttsChunks := []tts.Chunk{
+		{Audio: []byte("audio1"), IsLast: false},
+		{Audio: []byte("audio2"), IsLast: true},
+	}
+	mockTTS.On("SynthesizeStream", mock.Anything, mock.Anything, mock.Anything).Return(createTTSStream(ttsChunks), nil)
+
+	mockSender.On("SendTTSAudio", mock.Anything).Return(nil)
+
+	// 创建 Pipeline
+	pipeline := New(mockSTT, mockLLM, mockTTS, mockSession, "gpt-4o")
+
+	// 执行
+	ctx := context.Background()
+	err := pipeline.ProcessQuery(ctx, "session-123", req, nil, mockSender)
+
+	// 验证
+	assert.NoError(t, err)
+	assert.Len(t, mockSender.STTResults, 1)
+	assert.Equal(t, "你好，世界", mockSender.STTResults[0].Text)
+	assert.Len(t, mockSender.LLMChunks, 2)
+	assert.Len(t, mockSender.LLMDones, 1)
+	assert.Len(t, mockSender.TTSAudios, 2)
+
+	mockSTT.AssertExpectations(t)
+	mockLLM.AssertExpectations(t)
+	mockTTS.AssertExpectations(t)
+	mockSession.AssertExpectations(t)
+}
+
+// TestProcessQuery_STTError 测试 STT 失败降级
+func TestProcessQuery_STTError(t *testing.T) {
+	audioData := []byte("test audio")
+	audioBase64 := base64.StdEncoding.EncodeToString(audioData)
+
+	req := models.WsQuery{
+		Type:      "query",
+		RequestID: "req-123",
+		Audio:     audioBase64,
+	}
+
+	mockSTT := new(MockSTTService)
+	mockLLM := new(MockLLMService)
+	mockTTS := new(MockTTSService)
+	mockSession := new(MockSessionManager)
+	mockSender := NewMockSender()
+
+	mockSession.On("SetActiveRequest", mock.Anything, "session-123", "req-123").Return(nil)
+	mockSession.On("ClearActiveRequest", mock.Anything, "session-123").Return(nil)
+	mockSession.On("Get", mock.Anything, "session-123").Return(&models.Session{
+		ID: "session-123",
+		Config: models.SessionConfig{
+			Language: "zh-CN",
+		},
+	}, nil)
+
+	mockSTT.On("Recognize", mock.Anything, audioData, mock.Anything).
+		Return("", errors.New("STT service unavailable"))
+
+	mockSender.On("SendError", mock.Anything).Return(nil)
+
+	pipeline := New(mockSTT, mockLLM, mockTTS, mockSession, "gpt-4o")
+
+	ctx := context.Background()
+	err := pipeline.ProcessQuery(ctx, "session-123", req, nil, mockSender)
+
+	assert.Error(t, err)
+	assert.Len(t, mockSender.Errors, 1)
+	assert.Equal(t, "STT_ERROR", mockSender.Errors[0].Code)
+
+	mockSTT.AssertExpectations(t)
+	mockLLM.AssertNotCalled(t, "ChatStream")
+	mockTTS.AssertNotCalled(t, "SynthesizeStream")
+}
+
+// TestProcessQuery_LLMError 测试 LLM 失败降级
+func TestProcessQuery_LLMError(t *testing.T) {
+	audioData := []byte("test audio")
+	audioBase64 := base64.StdEncoding.EncodeToString(audioData)
+
+	req := models.WsQuery{
+		Type:      "query",
+		RequestID: "req-123",
+		Audio:     audioBase64,
+	}
+
+	session := &models.Session{
+		ID: "session-123",
+		Config: models.SessionConfig{
+			TTSEnabled: true,
+			Language:   "zh-CN",
+		},
+	}
+
+	mockSTT := new(MockSTTService)
+	mockLLM := new(MockLLMService)
+	mockTTS := new(MockTTSService)
+	mockSession := new(MockSessionManager)
+	mockSender := NewMockSender()
+
+	mockSession.On("SetActiveRequest", mock.Anything, "session-123", "req-123").Return(nil)
+	mockSession.On("ClearActiveRequest", mock.Anything, "session-123").Return(nil)
+	mockSession.On("Get", mock.Anything, "session-123").Return(session, nil)
+	mockSession.On("AppendMessage", mock.Anything, "session-123", mock.Anything).Return(nil)
+
+	mockSTT.On("Recognize", mock.Anything, audioData, mock.Anything).Return("你好", nil)
+	mockSender.On("SendSTTResult", mock.Anything).Return(nil)
+
+	mockLLM.On("ChatStream", mock.Anything, mock.Anything).
+		Return(nil, errors.New("LLM service unavailable"))
+
+	mockSender.On("SendError", mock.Anything).Return(nil)
+
+	pipeline := New(mockSTT, mockLLM, mockTTS, mockSession, "gpt-4o")
+
+	ctx := context.Background()
+	err := pipeline.ProcessQuery(ctx, "session-123", req, nil, mockSender)
+
+	assert.Error(t, err)
+	assert.Len(t, mockSender.Errors, 1)
+	assert.Equal(t, "LLM_ERROR", mockSender.Errors[0].Code)
+
+	mockSTT.AssertExpectations(t)
+	mockLLM.AssertExpectations(t)
+	mockTTS.AssertNotCalled(t, "SynthesizeStream")
+}
+
+// TestProcessQuery_TTSError 测试 TTS 失败静默跳过
+func TestProcessQuery_TTSError(t *testing.T) {
+	audioData := []byte("test audio")
+	audioBase64 := base64.StdEncoding.EncodeToString(audioData)
+
+	req := models.WsQuery{
+		Type:      "query",
+		RequestID: "req-123",
+		Audio:     audioBase64,
+	}
+
+	session := &models.Session{
+		ID: "session-123",
+		Config: models.SessionConfig{
+			TTSEnabled: true,
+			Language:   "zh-CN",
+		},
+	}
+
+	mockSTT := new(MockSTTService)
+	mockLLM := new(MockLLMService)
+	mockTTS := new(MockTTSService)
+	mockSession := new(MockSessionManager)
+	mockSender := NewMockSender()
+
+	mockSession.On("SetActiveRequest", mock.Anything, "session-123", "req-123").Return(nil)
+	mockSession.On("ClearActiveRequest", mock.Anything, "session-123").Return(nil)
+	mockSession.On("Get", mock.Anything, "session-123").Return(session, nil)
+	mockSession.On("AppendMessage", mock.Anything, "session-123", mock.Anything).Return(nil)
+
+	mockSTT.On("Recognize", mock.Anything, audioData, mock.Anything).Return("你好", nil)
+	mockSender.On("SendSTTResult", mock.Anything).Return(nil)
+
+	llmChunks := []llm.Chunk{
+		{Delta: "你好"},
+		{Done: true},
+	}
+	mockLLM.On("ChatStream", mock.Anything, mock.Anything).Return(createLLMStream(llmChunks), nil)
+	mockSender.On("SendLLMChunk", mock.Anything).Return(nil)
+	mockSender.On("SendLLMDone", mock.Anything).Return(nil)
+
+	mockTTS.On("SynthesizeStream", mock.Anything, mock.Anything, mock.Anything).
+		Return(nil, errors.New("TTS service unavailable"))
+
+	pipeline := New(mockSTT, mockLLM, mockTTS, mockSession, "gpt-4o")
+
+	ctx := context.Background()
+	err := pipeline.ProcessQuery(ctx, "session-123", req, nil, mockSender)
+
+	// TTS 失败应该静默跳过，不返回错误
+	assert.NoError(t, err)
+	assert.Len(t, mockSender.LLMDones, 1)
+	assert.Len(t, mockSender.TTSAudios, 0)
+
+	mockSTT.AssertExpectations(t)
+	mockLLM.AssertExpectations(t)
+	mockTTS.AssertExpectations(t)
+}
+
+// TestProcessQuery_ContextCancelled 测试上下文取消（Interrupt）
+func TestProcessQuery_ContextCancelled(t *testing.T) {
+	audioData := []byte("test audio")
+	audioBase64 := base64.StdEncoding.EncodeToString(audioData)
+
+	req := models.WsQuery{
+		Type:      "query",
+		RequestID: "req-123",
+		Audio:     audioBase64,
+	}
+
+	session := &models.Session{
+		ID: "session-123",
+		Config: models.SessionConfig{
+			TTSEnabled: true,
+			Language:   "zh-CN",
+		},
+	}
+
+	mockSTT := new(MockSTTService)
+	mockLLM := new(MockLLMService)
+	mockTTS := new(MockTTSService)
+	mockSession := new(MockSessionManager)
+	mockSender := NewMockSender()
+
+	mockSession.On("SetActiveRequest", mock.Anything, "session-123", "req-123").Return(nil)
+	mockSession.On("ClearActiveRequest", mock.Anything, "session-123").Return(nil)
+	mockSession.On("Get", mock.Anything, "session-123").Return(session, nil)
+	mockSession.On("AppendMessage", mock.Anything, "session-123", mock.Anything).Return(nil)
+
+	mockSTT.On("Recognize", mock.Anything, audioData, mock.Anything).Return("你好", nil)
+	mockSender.On("SendSTTResult", mock.Anything).Return(nil)
+
+	// 创建一个会延迟的 LLM 流，以便我们可以取消上下文
+	llmCh := make(chan llm.Chunk)
+	go func() {
+		time.Sleep(100 * time.Millisecond)
+		llmCh <- llm.Chunk{Delta: "你"}
+		time.Sleep(100 * time.Millisecond)
+		llmCh <- llm.Chunk{Delta: "好"}
+		close(llmCh)
+	}()
+
+	mockLLM.On("ChatStream", mock.Anything, mock.Anything).Return((<-chan llm.Chunk)(llmCh), nil)
+	mockSender.On("SendLLMChunk", mock.Anything).Return(nil)
+	mockSender.On("SendLLMDone", mock.Anything).Return(nil)
+
+	// 创建一个会延迟的 TTS 流
+	ttsCh := make(chan tts.Chunk)
+	go func() {
+		time.Sleep(200 * time.Millisecond)
+		close(ttsCh)
+	}()
+	mockTTS.On("SynthesizeStream", mock.Anything, mock.Anything, mock.Anything).Return((<-chan tts.Chunk)(ttsCh), nil)
+
+	pipeline := New(mockSTT, mockLLM, mockTTS, mockSession, "gpt-4o")
+
+	// 创建可取消的上下文
+	ctx, cancel := context.WithCancel(context.Background())
+
+	// 在 50ms 后取消
+	go func() {
+		time.Sleep(50 * time.Millisecond)
+		cancel()
+	}()
+
+	err := pipeline.ProcessQuery(ctx, "session-123", req, nil, mockSender)
+
+	// 上下文取消后，流程应该正常完成（中断流但不返回错误）
+	assert.NoError(t, err)
+
+	mockSTT.AssertExpectations(t)
+}
+
+// TestProcessQuery_DisabledTTS 测试 TTS 未启用的情况
+func TestProcessQuery_DisabledTTS(t *testing.T) {
+	audioData := []byte("test audio")
+	audioBase64 := base64.StdEncoding.EncodeToString(audioData)
+
+	req := models.WsQuery{
+		Type:      "query",
+		RequestID: "req-123",
+		Audio:     audioBase64,
+	}
+
+	session := &models.Session{
+		ID: "session-123",
+		Config: models.SessionConfig{
+			TTSEnabled: false, // TTS 未启用
+			Language:   "zh-CN",
+		},
+	}
+
+	mockSTT := new(MockSTTService)
+	mockLLM := new(MockLLMService)
+	mockTTS := new(MockTTSService)
+	mockSession := new(MockSessionManager)
+	mockSender := NewMockSender()
+
+	mockSession.On("SetActiveRequest", mock.Anything, "session-123", "req-123").Return(nil)
+	mockSession.On("ClearActiveRequest", mock.Anything, "session-123").Return(nil)
+	mockSession.On("Get", mock.Anything, "session-123").Return(session, nil)
+	mockSession.On("AppendMessage", mock.Anything, "session-123", mock.Anything).Return(nil)
+
+	mockSTT.On("Recognize", mock.Anything, audioData, mock.Anything).Return("你好", nil)
+	mockSender.On("SendSTTResult", mock.Anything).Return(nil)
+
+	llmChunks := []llm.Chunk{
+		{Delta: "你好"},
+		{Done: true},
+	}
+	mockLLM.On("ChatStream", mock.Anything, mock.Anything).Return(createLLMStream(llmChunks), nil)
+	mockSender.On("SendLLMChunk", mock.Anything).Return(nil)
+	mockSender.On("SendLLMDone", mock.Anything).Return(nil)
+
+	pipeline := New(mockSTT, mockLLM, mockTTS, mockSession, "gpt-4o")
+
+	ctx := context.Background()
+	err := pipeline.ProcessQuery(ctx, "session-123", req, nil, mockSender)
+
+	assert.NoError(t, err)
+	assert.Len(t, mockSender.LLMDones, 1)
+	assert.Len(t, mockSender.TTSAudios, 0)
+
+	// TTS 不应该被调用
+	mockTTS.AssertNotCalled(t, "SynthesizeStream")
+}
+
+// TestSplitter 测试句子切分器
+func TestSplitter(t *testing.T) {
+	ch := make(chan string, 10)
+	splitter := NewSplitter(ch)
+
+	// 输入包含多个句子的文本
+	splitter.Feed("你好。")
+	splitter.Feed("世界！")
+	splitter.Feed("这是")
+	splitter.Feed("一个测试。")
+	splitter.Flush()
+
+	// 应该有 3 个句子
+	assert.Equal(t, 3, len(ch))
+	assert.Equal(t, "你好。", <-ch)
+	assert.Equal(t, "世界！", <-ch)
+	assert.Equal(t, "这是一个测试。", <-ch)
+}
+
+// TestSplitter_NoDelimiter 测试没有分隔符的情况
+func TestSplitter_NoDelimiter(t *testing.T) {
+	ch := make(chan string, 10)
+	splitter := NewSplitter(ch)
+
+	splitter.Feed("没有分隔符的文本")
+	splitter.Flush()
+
+	// 应该有 1 个句子（Flush 会发送剩余内容）
+	assert.Equal(t, 1, len(ch))
+	assert.Equal(t, "没有分隔符的文本", <-ch)
+}
+
+// TestSplitter_Empty 测试空输入
+func TestSplitter_Empty(t *testing.T) {
+	ch := make(chan string, 10)
+	splitter := NewSplitter(ch)
+
+	splitter.Flush()
+
+	// 应该没有句子
+	assert.Equal(t, 0, len(ch))
+}
+
+// TestProcessQuery_InvalidAudio 测试无效音频数据
+func TestProcessQuery_InvalidAudio(t *testing.T) {
+	req := models.WsQuery{
+		Type:      "query",
+		RequestID: "req-123",
+		Audio:     "invalid-base64!!!",
+	}
+
+	mockSTT := new(MockSTTService)
+	mockLLM := new(MockLLMService)
+	mockTTS := new(MockTTSService)
+	mockSession := new(MockSessionManager)
+	mockSender := NewMockSender()
+
+	mockSender.On("SendError", mock.Anything).Return(nil)
+
+	pipeline := New(mockSTT, mockLLM, mockTTS, mockSession, "gpt-4o")
+
+	ctx := context.Background()
+	err := pipeline.ProcessQuery(ctx, "session-123", req, nil, mockSender)
+
+	assert.Error(t, err)
+	assert.Len(t, mockSender.Errors, 1)
+	assert.Equal(t, "INVALID_MESSAGE", mockSender.Errors[0].Code)
+}
+
+// TestProcessQuery_SessionNotFound 测试会话不存在
+func TestProcessQuery_SessionNotFound(t *testing.T) {
+	audioData := []byte("test audio")
+	audioBase64 := base64.StdEncoding.EncodeToString(audioData)
+
+	req := models.WsQuery{
+		Type:      "query",
+		RequestID: "req-123",
+		Audio:     audioBase64,
+	}
+
+	mockSTT := new(MockSTTService)
+	mockLLM := new(MockLLMService)
+	mockTTS := new(MockTTSService)
+	mockSession := new(MockSessionManager)
+	mockSender := NewMockSender()
+
+	mockSession.On("SetActiveRequest", mock.Anything, "session-123", "req-123").Return(nil)
+	mockSession.On("ClearActiveRequest", mock.Anything, "session-123").Return(nil)
+	mockSession.On("Get", mock.Anything, "session-123").Return(nil, errors.New("session not found"))
+
+	mockSender.On("SendError", mock.Anything).Return(nil)
+
+	pipeline := New(mockSTT, mockLLM, mockTTS, mockSession, "gpt-4o")
+
+	ctx := context.Background()
+	err := pipeline.ProcessQuery(ctx, "session-123", req, nil, mockSender)
+
+	assert.Error(t, err)
+	assert.Len(t, mockSender.Errors, 1)
+	assert.Equal(t, "SESSION_NOT_FOUND", mockSender.Errors[0].Code)
+}
--- a/backend/internal/orchestrator/sender.go
+++ b/backend/internal/orchestrator/sender.go
@@ -0,0 +1,22 @@
+package orchestrator
+
+import "github.com/hhs/camtalk/internal/models"
+
+// Sender 抽象 WebSocket 消息推送能力。
+// 便于测试时 mock，避免依赖真实 WebSocket 连接。
+type Sender interface {
+	// SendSTTResult 发送语音识别结果。
+	SendSTTResult(result models.WsSTTResult) error
+
+	// SendLLMChunk 发送 LLM 流式文本增量。
+	SendLLMChunk(chunk models.WsLLMChunk) error
+
+	// SendLLMDone 发送 LLM 流结束信号。
+	SendLLMDone(done models.WsLLMDone) error
+
+	// SendTTSAudio 发送 TTS 音频数据。
+	SendTTSAudio(audio models.WsTTSAudio) error
+
+	// SendError 发送错误消息。
+	SendError(err models.WsError) error
+}
--- a/backend/internal/orchestrator/splitter.go
+++ b/backend/internal/orchestrator/splitter.go
@@ -0,0 +1,55 @@
+package orchestrator
+
+import "strings"
+
+// sentenceDelimiters 句子分隔符集合。
+var sentenceDelimiters = map[rune]bool{
+	'。': true,
+	'！': true,
+	'？': true,
+	'\n': true,
+	'.':  true,
+	'!':  true,
+	'?':  true,
+}
+
+// Splitter 句子切分器。
+// 将流式文本按句子边界切分，发送到 channel 供 TTS 合成。
+type Splitter struct {
+	ch      chan<- string
+	buffer  strings.Builder
+}
+
+// NewSplitter 创建句子切分器。
+// ch 用于接收切分后的句子文本。
+func NewSplitter(ch chan<- string) *Splitter {
+	return &Splitter{
+		ch: ch,
+	}
+}
+
+// Feed 输入增量文本，遇到句子分隔符时发送完整句子。
+func (s *Splitter) Feed(delta string) {
+	for _, r := range delta {
+		s.buffer.WriteRune(r)
+		if sentenceDelimiters[r] {
+			s.flushBuffer()
+		}
+	}
+}
+
+// Flush 刷新缓冲区中的剩余文本（即使没有句子分隔符）。
+func (s *Splitter) Flush() {
+	if s.buffer.Len() > 0 {
+		s.flushBuffer()
+	}
+}
+
+// flushBuffer 将缓冲区内容发送到 channel 并清空。
+func (s *Splitter) flushBuffer() {
+	text := strings.TrimSpace(s.buffer.String())
+	if text != "" {
+		s.ch <- text
+	}
+	s.buffer.Reset()
+}
--- a/backend/internal/session/manager.go
+++ b/backend/internal/session/manager.go
@@ -0,0 +1,49 @@
+// Package session 提供会话生命周期管理能力。
+package session
+
+import (
+	"context"
+	"errors"
+
+	"github.com/hhs/camtalk/internal/models"
+)
+
+// ErrSessionNotFound 会话不存在或已过期。
+var ErrSessionNotFound = errors.New("session not found")
+
+// Manager 会话管理器接口。
+// WebSocket Handler 通过此接口操作会话，不直接接触存储层。
+type Manager interface {
+	// Create 创建新会话，返回 session ID。
+	Create(ctx context.Context, config models.SessionConfig) (string, error)
+
+	// Get 获取会话（含 config）。不存在返回 ErrSessionNotFound。
+	Get(ctx context.Context, sessionID string) (*models.Session, error)
+
+	// UpdateConfig 更新会话配置（config 消息触发）。
+	UpdateConfig(ctx context.Context, sessionID string, patch models.SessionConfigPatch) error
+
+	// GetHistory 获取最近 N 轮对话历史（供 Orchestrator 构建 LLM 上下文）。
+	GetHistory(ctx context.Context, sessionID string, limit int) ([]models.Message, error)
+
+	// AppendMessage 追加一条对话消息，同时刷新 TTL。
+	AppendMessage(ctx context.Context, sessionID string, msg models.Message) error
+
+	// SetActiveRequest 标记当前正在处理的请求 ID（interrupt 用）。
+	SetActiveRequest(ctx context.Context, sessionID string, requestID string) error
+
+	// GetActiveRequestID 获取当前活跃请求 ID。
+	GetActiveRequestID(ctx context.Context, sessionID string) (string, error)
+
+	// ClearActiveRequest 清除活跃请求标记（请求完成或中断后）。
+	ClearActiveRequest(ctx context.Context, sessionID string) error
+
+	// Touch 刷新 TTL（心跳时调用）。
+	Touch(ctx context.Context, sessionID string) error
+
+	// Destroy 显式销毁会话（REST API DELETE 或连接断开清理）。
+	Destroy(ctx context.Context, sessionID string) error
+
+	// ActiveCount 返回当前活跃会话数（健康检查用）。
+	ActiveCount() int
+}
--- a/backend/internal/session/memory.go
+++ b/backend/internal/session/memory.go
@@ -0,0 +1,275 @@
+package session
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	"github.com/google/uuid"
+
+	"github.com/hhs/camtalk/internal/logger"
+	"github.com/hhs/camtalk/internal/models"
+)
+
+const (
+	defaultTTL         = 30 * time.Minute
+	defaultHistorySize = 20
+)
+
+// sessionEntry 内部会话条目。
+type sessionEntry struct {
+	session     models.Session
+	history     []models.Message
+	activeReqID string
+	lastActive  time.Time
+}
+
+// MemoryManager 基于内存的 SessionManager 实现。
+// 适用于 MVP 和无 Redis 的开发环境。
+type MemoryManager struct {
+	mu          sync.RWMutex
+	sessions    map[string]*sessionEntry
+	ttl         time.Duration
+	maxHistory  int
+	stopCleaner chan struct{}
+}
+
+// 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 {
+	if ttl <= 0 {
+		ttl = defaultTTL
+	}
+	if maxHistory <= 0 {
+		maxHistory = defaultHistorySize
+	}
+
+	m := &MemoryManager{
+		sessions:    make(map[string]*sessionEntry),
+		ttl:         ttl,
+		maxHistory:  maxHistory,
+		stopCleaner: make(chan struct{}),
+	}
+
+	// 启动后台清理 goroutine，每分钟清除过期会话。
+	go m.cleanLoop()
+
+	return m
+}
+
+// cleanLoop 后台定期清理过期会话。
+func (m *MemoryManager) cleanLoop() {
+	ticker := time.NewTicker(1 * time.Minute)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-ticker.C:
+			m.cleanExpired()
+		case <-m.stopCleaner:
+			return
+		}
+	}
+}
+
+// cleanExpired 清除所有过期会话。
+func (m *MemoryManager) cleanExpired() {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	now := time.Now()
+	for id, entry := range m.sessions {
+		if now.Sub(entry.lastActive) > m.ttl {
+			delete(m.sessions, id)
+			logger.Log.Debugw("session expired (cleaner)", "session", id)
+		}
+	}
+}
+
+// Stop 停止后台清理 goroutine。应用退出前调用。
+func (m *MemoryManager) Stop() {
+	close(m.stopCleaner)
+}
+
+// isExpired 检查会话是否过期（调用方需持锁或在已知 entry 存在时调用）。
+func (m *MemoryManager) isExpired(entry *sessionEntry) bool {
+	return time.Since(entry.lastActive) > m.ttl
+}
+
+// Create 创建新会话。
+func (m *MemoryManager) Create(_ context.Context, config models.SessionConfig) (string, error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	id := uuid.New().String()
+	now := time.Now()
+	m.sessions[id] = &sessionEntry{
+		session: models.Session{
+			ID:        id,
+			CreatedAt: now,
+			Config:    config,
+		},
+		history:    make([]models.Message, 0),
+		lastActive: now,
+	}
+
+	logger.Log.Debugw("session created", "session", id)
+	return id, nil
+}
+
+// Get 获取会话。
+func (m *MemoryManager) Get(_ context.Context, sessionID string) (*models.Session, error) {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+
+	entry, ok := m.sessions[sessionID]
+	if !ok || m.isExpired(entry) {
+		return nil, ErrSessionNotFound
+	}
+
+	sess := entry.session // 复制一份返回
+	return &sess, nil
+}
+
+// UpdateConfig 更新会话配置。
+func (m *MemoryManager) UpdateConfig(_ context.Context, sessionID string, patch models.SessionConfigPatch) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	entry, ok := m.sessions[sessionID]
+	if !ok || m.isExpired(entry) {
+		return ErrSessionNotFound
+	}
+
+	patch.Apply(&entry.session.Config)
+	entry.lastActive = time.Now()
+
+	logger.Log.Debugw("session config updated", "session", sessionID)
+	return nil
+}
+
+// GetHistory 获取最近 N 轮对话历史。
+func (m *MemoryManager) GetHistory(_ context.Context, sessionID string, limit int) ([]models.Message, error) {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+
+	entry, ok := m.sessions[sessionID]
+	if !ok || m.isExpired(entry) {
+		return nil, ErrSessionNotFound
+	}
+
+	if limit <= 0 || limit > len(entry.history) {
+		limit = len(entry.history)
+	}
+
+	// 返回最近 limit 条的副本
+	result := make([]models.Message, limit)
+	copy(result, entry.history[len(entry.history)-limit:])
+	return result, nil
+}
+
+// AppendMessage 追加一条对话消息，同时刷新 TTL。
+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) {
+		return ErrSessionNotFound
+	}
+
+	entry.history = append(entry.history, msg)
+
+	// 超过上限时裁剪，保留最新的 maxHistory 条
+	if len(entry.history) > m.maxHistory {
+		entry.history = entry.history[len(entry.history)-m.maxHistory:]
+	}
+
+	entry.lastActive = time.Now()
+	return nil
+}
+
+// SetActiveRequest 标记当前正在处理的请求 ID。
+func (m *MemoryManager) SetActiveRequest(_ context.Context, sessionID string, requestID string) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	entry, ok := m.sessions[sessionID]
+	if !ok || m.isExpired(entry) {
+		return ErrSessionNotFound
+	}
+
+	entry.activeReqID = requestID
+	entry.lastActive = time.Now()
+	return nil
+}
+
+// GetActiveRequestID 获取当前活跃请求 ID。
+func (m *MemoryManager) GetActiveRequestID(_ context.Context, sessionID string) (string, error) {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+
+	entry, ok := m.sessions[sessionID]
+	if !ok || m.isExpired(entry) {
+		return "", ErrSessionNotFound
+	}
+
+	return entry.activeReqID, nil
+}
+
+// ClearActiveRequest 清除活跃请求标记。
+func (m *MemoryManager) ClearActiveRequest(_ context.Context, sessionID string) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	entry, ok := m.sessions[sessionID]
+	if !ok || m.isExpired(entry) {
+		return ErrSessionNotFound
+	}
+
+	entry.activeReqID = ""
+	entry.lastActive = time.Now()
+	return nil
+}
+
+// Touch 刷新 TTL。
+func (m *MemoryManager) Touch(_ context.Context, sessionID string) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	entry, ok := m.sessions[sessionID]
+	if !ok || m.isExpired(entry) {
+		return ErrSessionNotFound
+	}
+
+	entry.lastActive = time.Now()
+	return nil
+}
+
+// Destroy 显式销毁会话。
+func (m *MemoryManager) Destroy(_ context.Context, sessionID string) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if _, ok := m.sessions[sessionID]; !ok {
+		return ErrSessionNotFound
+	}
+
+	delete(m.sessions, sessionID)
+	logger.Log.Debugw("session destroyed", "session", sessionID)
+	return nil
+}
+
+// ActiveCount 返回当前活跃会话数。
+func (m *MemoryManager) ActiveCount() int {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+
+	now := time.Now()
+	count := 0
+	for _, entry := range m.sessions {
+		if now.Sub(entry.lastActive) <= m.ttl {
+			count++
+		}
+	}
+	return count
+}
--- a/backend/internal/session/memory_test.go
+++ b/backend/internal/session/memory_test.go
@@ -0,0 +1,286 @@
+package session
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/hhs/camtalk/internal/logger"
+	"github.com/hhs/camtalk/internal/models"
+)
+
+func init() {
+	logger.Init("debug", "console")
+}
+
+func TestCreateAndGet(t *testing.T) {
+	m := NewMemoryManager(30*time.Minute, 20)
+	defer m.Stop()
+	ctx := context.Background()
+
+	config := models.DefaultConfig()
+	id, err := m.Create(ctx, config)
+	if err != nil {
+		t.Fatalf("Create: %v", err)
+	}
+	if id == "" {
+		t.Fatal("Create returned empty ID")
+	}
+
+	sess, err := m.Get(ctx, id)
+	if err != nil {
+		t.Fatalf("Get: %v", err)
+	}
+	if sess.ID != id {
+		t.Errorf("ID = %q, want %q", sess.ID, id)
+	}
+	if sess.Config.Language != "zh-CN" {
+		t.Errorf("Language = %q, want %q", sess.Config.Language, "zh-CN")
+	}
+}
+
+func TestGetNotFound(t *testing.T) {
+	m := NewMemoryManager(30*time.Minute, 20)
+	defer m.Stop()
+	ctx := context.Background()
+
+	_, err := m.Get(ctx, "nonexistent")
+	if err != ErrSessionNotFound {
+		t.Errorf("Get nonexistent: err = %v, want ErrSessionNotFound", err)
+	}
+}
+
+func TestExpire(t *testing.T) {
+	// 使用极短 TTL 测试过期
+	m := NewMemoryManager(50*time.Millisecond, 20)
+	defer m.Stop()
+	ctx := context.Background()
+
+	id, _ := m.Create(ctx, models.DefaultConfig())
+
+	// 未过期时应能获取
+	_, err := m.Get(ctx, id)
+	if err != nil {
+		t.Fatalf("Get before expire: %v", err)
+	}
+
+	// 等待过期
+	time.Sleep(80 * time.Millisecond)
+
+	_, err = m.Get(ctx, id)
+	if err != ErrSessionNotFound {
+		t.Errorf("Get after expire: err = %v, want ErrSessionNotFound", err)
+	}
+}
+
+func TestDestroy(t *testing.T) {
+	m := NewMemoryManager(30*time.Minute, 20)
+	defer m.Stop()
+	ctx := context.Background()
+
+	id, _ := m.Create(ctx, models.DefaultConfig())
+
+	if err := m.Destroy(ctx, id); err != nil {
+		t.Fatalf("Destroy: %v", err)
+	}
+
+	_, err := m.Get(ctx, id)
+	if err != ErrSessionNotFound {
+		t.Errorf("Get after Destroy: err = %v, want ErrSessionNotFound", err)
+	}
+}
+
+func TestDestroyNotFound(t *testing.T) {
+	m := NewMemoryManager(30*time.Minute, 20)
+	defer m.Stop()
+	ctx := context.Background()
+
+	err := m.Destroy(ctx, "nonexistent")
+	if err != ErrSessionNotFound {
+		t.Errorf("Destroy nonexistent: err = %v, want ErrSessionNotFound", err)
+	}
+}
+
+func TestAppendMessageAndGetHistory(t *testing.T) {
+	m := NewMemoryManager(30*time.Minute, 20)
+	defer m.Stop()
+	ctx := context.Background()
+
+	id, _ := m.Create(ctx, models.DefaultConfig())
+
+	msgs := []models.Message{
+		{Role: "user", Content: "你好"},
+		{Role: "assistant", Content: "你好！有什么可以帮你的吗？"},
+		{Role: "user", Content: "这是什么？"},
+		{Role: "assistant", Content: "这是一朵花。"},
+	}
+
+	for _, msg := range msgs {
+		if err := m.AppendMessage(ctx, id, msg); err != nil {
+			t.Fatalf("AppendMessage: %v", err)
+		}
+	}
+
+	history, err := m.GetHistory(ctx, id, 0)
+	if err != nil {
+		t.Fatalf("GetHistory: %v", err)
+	}
+	if len(history) != 4 {
+		t.Fatalf("GetHistory len = %d, want 4", len(history))
+	}
+	if history[0].Content != "你好" {
+		t.Errorf("history[0] = %q, want %q", history[0].Content, "你好")
+	}
+}
+
+func TestGetHistoryLimit(t *testing.T) {
+	m := NewMemoryManager(30*time.Minute, 20)
+	defer m.Stop()
+	ctx := context.Background()
+
+	id, _ := m.Create(ctx, models.DefaultConfig())
+
+	for i := 0; i < 10; i++ {
+		m.AppendMessage(ctx, id, models.Message{Role: "user", Content: "msg"})
+	}
+
+	history, err := m.GetHistory(ctx, id, 3)
+	if err != nil {
+		t.Fatalf("GetHistory: %v", err)
+	}
+	if len(history) != 3 {
+		t.Fatalf("GetHistory limit=3: len = %d, want 3", len(history))
+	}
+}
+
+func TestHistoryLimit(t *testing.T) {
+	const maxHistory = 5
+	m := NewMemoryManager(30*time.Minute, maxHistory)
+	defer m.Stop()
+	ctx := context.Background()
+
+	id, _ := m.Create(ctx, models.DefaultConfig())
+
+	// 插入超过上限的消息
+	for i := 0; i < 10; i++ {
+		m.AppendMessage(ctx, id, models.Message{Role: "user", Content: "msg"})
+	}
+
+	history, err := m.GetHistory(ctx, id, 0)
+	if err != nil {
+		t.Fatalf("GetHistory: %v", err)
+	}
+	if len(history) != maxHistory {
+		t.Fatalf("GetHistory after overflow: len = %d, want %d", len(history), maxHistory)
+	}
+}
+
+func TestUpdateConfig(t *testing.T) {
+	m := NewMemoryManager(30*time.Minute, 20)
+	defer m.Stop()
+	ctx := context.Background()
+
+	id, _ := m.Create(ctx, models.DefaultConfig())
+
+	ttsEnabled := false
+	detailLevel := "high"
+	patch := models.SessionConfigPatch{
+		TTSEnabled:  &ttsEnabled,
+		DetailLevel: &detailLevel,
+	}
+
+	if err := m.UpdateConfig(ctx, id, patch); err != nil {
+		t.Fatalf("UpdateConfig: %v", err)
+	}
+
+	sess, _ := m.Get(ctx, id)
+	if sess.Config.TTSEnabled != false {
+		t.Errorf("TTSEnabled = %v, want false", sess.Config.TTSEnabled)
+	}
+	if sess.Config.DetailLevel != "high" {
+		t.Errorf("DetailLevel = %q, want %q", sess.Config.DetailLevel, "high")
+	}
+	// Language 未传，应保持原值
+	if sess.Config.Language != "zh-CN" {
+		t.Errorf("Language = %q, want %q", sess.Config.Language, "zh-CN")
+	}
+}
+
+func TestActiveRequest(t *testing.T) {
+	m := NewMemoryManager(30*time.Minute, 20)
+	defer m.Stop()
+	ctx := context.Background()
+
+	id, _ := m.Create(ctx, models.DefaultConfig())
+
+	// 初始应为空
+	reqID, err := m.GetActiveRequestID(ctx, id)
+	if err != nil {
+		t.Fatalf("GetActiveRequestID: %v", err)
+	}
+	if reqID != "" {
+		t.Errorf("initial active request = %q, want empty", reqID)
+	}
+
+	// 设置
+	if err := m.SetActiveRequest(ctx, id, "req-123"); err != nil {
+		t.Fatalf("SetActiveRequest: %v", err)
+	}
+	reqID, _ = m.GetActiveRequestID(ctx, id)
+	if reqID != "req-123" {
+		t.Errorf("active request = %q, want %q", reqID, "req-123")
+	}
+
+	// 清除
+	if err := m.ClearActiveRequest(ctx, id); err != nil {
+		t.Fatalf("ClearActiveRequest: %v", err)
+	}
+	reqID, _ = m.GetActiveRequestID(ctx, id)
+	if reqID != "" {
+		t.Errorf("active request after clear = %q, want empty", reqID)
+	}
+}
+
+func TestTouchRefreshesTTL(t *testing.T) {
+	m := NewMemoryManager(100*time.Millisecond, 20)
+	defer m.Stop()
+	ctx := context.Background()
+
+	id, _ := m.Create(ctx, models.DefaultConfig())
+
+	// 50ms 后 Touch，应重置 TTL
+	time.Sleep(50 * time.Millisecond)
+	if err := m.Touch(ctx, id); err != nil {
+		t.Fatalf("Touch: %v", err)
+	}
+
+	// 再等 70ms（距创建 120ms，但距 Touch 只有 70ms），不应过期
+	time.Sleep(70 * time.Millisecond)
+	_, err := m.Get(ctx, id)
+	if err != nil {
+		t.Errorf("Get after Touch: %v, want nil (should not expire yet)", err)
+	}
+
+	// 再等 50ms（距 Touch 120ms），应过期
+	time.Sleep(50 * time.Millisecond)
+	_, err = m.Get(ctx, id)
+	if err != ErrSessionNotFound {
+		t.Errorf("Get after TTL: err = %v, want ErrSessionNotFound", err)
+	}
+}
+
+func TestActiveCount(t *testing.T) {
+	m := NewMemoryManager(30*time.Minute, 20)
+	defer m.Stop()
+	ctx := context.Background()
+
+	if m.ActiveCount() != 0 {
+		t.Errorf("initial ActiveCount = %d, want 0", m.ActiveCount())
+	}
+
+	m.Create(ctx, models.DefaultConfig())
+	m.Create(ctx, models.DefaultConfig())
+	if m.ActiveCount() != 2 {
+		t.Errorf("ActiveCount = %d, want 2", m.ActiveCount())
+	}
+}
--- a/backend/internal/session/redis.go
+++ b/backend/internal/session/redis.go
@@ -0,0 +1,324 @@
+package session
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"strconv"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/redis/go-redis/v9"
+
+	"github.com/hhs/camtalk/internal/logger"
+	"github.com/hhs/camtalk/internal/models"
+)
+
+// RedisManager 基于 Redis 的 SessionManager 实现。
+// 数据结构：
+//   - session:{id}:meta    → Hash（会话元数据）
+//   - session:{id}:history → List（对话历史）
+type RedisManager struct {
+	rdb        *redis.Client
+	ttl        time.Duration
+	maxHistory int
+}
+
+// NewRedisManager 创建 Redis 版 SessionManager。
+func NewRedisManager(rdb *redis.Client, ttl time.Duration, maxHistory int) *RedisManager {
+	if ttl <= 0 {
+		ttl = defaultTTL
+	}
+	if maxHistory <= 0 {
+		maxHistory = defaultHistorySize
+	}
+	return &RedisManager{rdb: rdb, ttl: ttl, maxHistory: maxHistory}
+}
+
+func metaKey(id string) string   { return fmt.Sprintf("session:%s:meta", id) }
+func histKey(id string) string   { return fmt.Sprintf("session:%s:history", id) }
+
+// Create 创建新会话。
+func (m *RedisManager) Create(ctx context.Context, config models.SessionConfig) (string, error) {
+	id := uuidNew()
+	now := time.Now().UTC()
+
+	pipe := m.rdb.Pipeline()
+
+	// 写入 meta Hash
+	pipe.HSet(ctx, metaKey(id), map[string]interface{}{
+		"session_id":         id,
+		"config.tts_enabled": strconv.FormatBool(config.TTSEnabled),
+		"config.detail_level": config.DetailLevel,
+		"config.language":    config.Language,
+		"created_at":         now.Format(time.RFC3339),
+		"last_active":        now.Format(time.RFC3339),
+		"active_request_id":  "",
+	})
+	pipe.Expire(ctx, metaKey(id), m.ttl)
+
+	// 初始化空 history List
+	pipe.RPush(ctx, histKey(id), placeholderHistoryMark)
+	pipe.Expire(ctx, histKey(id), m.ttl)
+
+	if _, err := pipe.Exec(ctx); err != nil {
+		return "", fmt.Errorf("redis create session: %w", err)
+	}
+
+	logger.Log.Debugw("redis session created", "session", id)
+	return id, nil
+}
+
+// placeholderHistoryMark 占位符，避免 Redis 对空 key 的特殊行为。
+const placeholderHistoryMark = "__placeholder__"
+
+// Get 获取会话。
+func (m *RedisManager) Get(ctx context.Context, sessionID string) (*models.Session, error) {
+	vals, err := m.rdb.HGetAll(ctx, metaKey(sessionID)).Result()
+	if err != nil {
+		return nil, fmt.Errorf("redis get session: %w", err)
+	}
+	if len(vals) == 0 {
+		return nil, ErrSessionNotFound
+	}
+
+	sess := &models.Session{
+		ID: vals["session_id"],
+	}
+	sess.CreatedAt, _ = time.Parse(time.RFC3339, vals["created_at"])
+	sess.Config.TTSEnabled, _ = strconv.ParseBool(vals["config.tts_enabled"])
+	sess.Config.DetailLevel = vals["config.detail_level"]
+	sess.Config.Language = vals["config.language"]
+
+	return sess, nil
+}
+
+// UpdateConfig 更新会话配置。
+func (m *RedisManager) UpdateConfig(ctx context.Context, sessionID string, patch models.SessionConfigPatch) error {
+	// 先检查会话是否存在
+	exists, err := m.rdb.Exists(ctx, metaKey(sessionID)).Result()
+	if err != nil {
+		return fmt.Errorf("redis check session: %w", err)
+	}
+	if exists == 0 {
+		return ErrSessionNotFound
+	}
+
+	fields := map[string]interface{}{
+		"last_active": time.Now().UTC().Format(time.RFC3339),
+	}
+	if patch.TTSEnabled != nil {
+		fields["config.tts_enabled"] = strconv.FormatBool(*patch.TTSEnabled)
+	}
+	if patch.DetailLevel != nil {
+		fields["config.detail_level"] = *patch.DetailLevel
+	}
+	if patch.Language != nil {
+		fields["config.language"] = *patch.Language
+	}
+
+	if err := m.rdb.HSet(ctx, metaKey(sessionID), fields).Err(); err != nil {
+		return fmt.Errorf("redis update config: %w", err)
+	}
+
+	// 刷新 TTL
+	m.rdb.Expire(ctx, metaKey(sessionID), m.ttl)
+	logger.Log.Debugw("redis session config updated", "session", sessionID)
+	return nil
+}
+
+// GetHistory 获取最近 N 轮对话历史。
+func (m *RedisManager) GetHistory(ctx context.Context, sessionID string, limit int) ([]models.Message, error) {
+	// 检查会话是否存在
+	exists, err := m.rdb.Exists(ctx, metaKey(sessionID)).Result()
+	if err != nil {
+		return nil, fmt.Errorf("redis check session: %w", err)
+	}
+	if exists == 0 {
+		return nil, ErrSessionNotFound
+	}
+
+	if limit <= 0 {
+		limit = m.maxHistory
+	}
+
+	// LRANGE 0 {limit-1}，最新在前（LPUSH），需要反转为时间顺序
+	raws, err := m.rdb.LRange(ctx, histKey(sessionID), 0, int64(limit)).Result()
+	if err != nil {
+		return nil, fmt.Errorf("redis get history: %w", err)
+	}
+
+	var msgs []models.Message
+	for _, raw := range raws {
+		if raw == placeholderHistoryMark {
+			continue
+		}
+		var msg models.Message
+		if err := json.Unmarshal([]byte(raw), &msg); err != nil {
+			logger.Log.Warnw("invalid history entry", "session", sessionID, "raw", raw)
+			continue
+		}
+		msgs = append(msgs, msg)
+	}
+
+	// 反转为时间顺序（LPUSH 最新在前 → 需要最旧在前）
+	for i, j := 0, len(msgs)-1; i < j; i, j = i+1, j-1 {
+		msgs[i], msgs[j] = msgs[j], msgs[i]
+	}
+
+	return msgs, nil
+}
+
+// AppendMessage 追加一条对话消息，同时刷新 TTL。
+func (m *RedisManager) AppendMessage(ctx context.Context, sessionID string, msg models.Message) error {
+	// 检查会话是否存在
+	exists, err := m.rdb.Exists(ctx, metaKey(sessionID)).Result()
+	if err != nil {
+		return fmt.Errorf("redis check session: %w", err)
+	}
+	if exists == 0 {
+		return ErrSessionNotFound
+	}
+
+	data, err := json.Marshal(msg)
+	if err != nil {
+		return fmt.Errorf("marshal message: %w", err)
+	}
+
+	pipe := m.rdb.Pipeline()
+	// LPUSH 新消息到左头（最新在前）
+	pipe.LPush(ctx, histKey(sessionID), string(data))
+	// LTRIM 保留最近 maxHistory 条（+1 是因为有占位符）
+	pipe.LTrim(ctx, histKey(sessionID), 0, int64(m.maxHistory))
+	// 刷新 TTL
+	pipe.Expire(ctx, histKey(sessionID), m.ttl)
+	pipe.Expire(ctx, metaKey(sessionID), m.ttl)
+	// 更新 last_active
+	pipe.HSet(ctx, metaKey(sessionID), "last_active", time.Now().UTC().Format(time.RFC3339))
+
+	if _, err := pipe.Exec(ctx); err != nil {
+		return fmt.Errorf("redis append message: %w", err)
+	}
+
+	return nil
+}
+
+// SetActiveRequest 标记当前正在处理的请求 ID。
+func (m *RedisManager) SetActiveRequest(ctx context.Context, sessionID string, requestID string) error {
+	exists, err := m.rdb.Exists(ctx, metaKey(sessionID)).Result()
+	if err != nil {
+		return fmt.Errorf("redis check session: %w", err)
+	}
+	if exists == 0 {
+		return ErrSessionNotFound
+	}
+
+	pipe := m.rdb.Pipeline()
+	pipe.HSet(ctx, metaKey(sessionID), "active_request_id", requestID)
+	pipe.HSet(ctx, metaKey(sessionID), "last_active", time.Now().UTC().Format(time.RFC3339))
+	pipe.Expire(ctx, metaKey(sessionID), m.ttl)
+
+	if _, err := pipe.Exec(ctx); err != nil {
+		return fmt.Errorf("redis set active request: %w", err)
+	}
+	return nil
+}
+
+// GetActiveRequestID 获取当前活跃请求 ID。
+func (m *RedisManager) GetActiveRequestID(ctx context.Context, sessionID string) (string, error) {
+	val, err := m.rdb.HGet(ctx, metaKey(sessionID), "active_request_id").Result()
+	if err == redis.Nil {
+		return "", ErrSessionNotFound
+	}
+	if err != nil {
+		return "", fmt.Errorf("redis get active request: %w", err)
+	}
+	return val, nil
+}
+
+// ClearActiveRequest 清除活跃请求标记。
+func (m *RedisManager) ClearActiveRequest(ctx context.Context, sessionID string) error {
+	exists, err := m.rdb.Exists(ctx, metaKey(sessionID)).Result()
+	if err != nil {
+		return fmt.Errorf("redis check session: %w", err)
+	}
+	if exists == 0 {
+		return ErrSessionNotFound
+	}
+
+	pipe := m.rdb.Pipeline()
+	pipe.HSet(ctx, metaKey(sessionID), "active_request_id", "")
+	pipe.HSet(ctx, metaKey(sessionID), "last_active", time.Now().UTC().Format(time.RFC3339))
+	pipe.Expire(ctx, metaKey(sessionID), m.ttl)
+
+	if _, err := pipe.Exec(ctx); err != nil {
+		return fmt.Errorf("redis clear active request: %w", err)
+	}
+	return nil
+}
+
+// Touch 刷新 TTL。
+func (m *RedisManager) Touch(ctx context.Context, sessionID string) error {
+	exists, err := m.rdb.Exists(ctx, metaKey(sessionID)).Result()
+	if err != nil {
+		return fmt.Errorf("redis check session: %w", err)
+	}
+	if exists == 0 {
+		return ErrSessionNotFound
+	}
+
+	pipe := m.rdb.Pipeline()
+	pipe.Expire(ctx, metaKey(sessionID), m.ttl)
+	pipe.Expire(ctx, histKey(sessionID), m.ttl)
+	pipe.HSet(ctx, metaKey(sessionID), "last_active", time.Now().UTC().Format(time.RFC3339))
+
+	if _, err := pipe.Exec(ctx); err != nil {
+		return fmt.Errorf("redis touch: %w", err)
+	}
+	return nil
+}
+
+// Destroy 显式销毁会话。
+func (m *RedisManager) Destroy(ctx context.Context, sessionID string) error {
+	deleted, err := m.rdb.Del(ctx, metaKey(sessionID), histKey(sessionID)).Result()
+	if err != nil {
+		return fmt.Errorf("redis destroy session: %w", err)
+	}
+	if deleted == 0 {
+		return ErrSessionNotFound
+	}
+
+	logger.Log.Debugw("redis session destroyed", "session", sessionID)
+	return nil
+}
+
+// ActiveCount 返回当前活跃会话数。
+// Redis 实现通过 SCAN 遍历 meta key，适用于中等规模。
+// 大规模部署建议维护独立的活跃会话集合。
+func (m *RedisManager) ActiveCount() int {
+	ctx := context.Background()
+	count := 0
+	var cursor uint64
+	for {
+		keys, nextCursor, err := m.rdb.Scan(ctx, cursor, "session:*:meta", 100).Result()
+		if err != nil {
+			break
+		}
+		for _, key := range keys {
+			exists, _ := m.rdb.Exists(ctx, key).Result()
+			if exists > 0 {
+				count++
+			}
+		}
+		cursor = nextCursor
+		if cursor == 0 {
+			break
+		}
+	}
+	return count
+}
+
+// uuidNew 生成 UUID，便于测试时 mock。
+var uuidNew = func() string {
+	return uuid.New().String()
+}
--- a/backend/internal/ws/handler.go
+++ b/backend/internal/ws/handler.go
@@ -1,17 +1,20 @@
 package ws

 import (
+	"context"
 	"encoding/json"
-	"log"
 	"net/http"
 	"sync"
 	"time"

 	"github.com/gin-gonic/gin"
-	"github.com/google/uuid"
 	"github.com/gorilla/websocket"

+	"github.com/hhs/camtalk/internal/errors"
+	"github.com/hhs/camtalk/internal/logger"
 	"github.com/hhs/camtalk/internal/models"
+	"github.com/hhs/camtalk/internal/orchestrator"
+	"github.com/hhs/camtalk/internal/session"
 )

 var upgrader = websocket.Upgrader{
@@ -20,36 +23,94 @@ var upgrader = websocket.Upgrader{

 // Client 代表一个 WebSocket 客户端连接。
 type Client struct {
-	conn      *websocket.Conn
-	sessionID string
-	mu        sync.Mutex
+	conn          *websocket.Conn
+	sessionID     string
+	sessionMgr    session.Manager
+	orchestrator  orchestrator.Orchestrator
+	cancelFuncs   map[string]context.CancelFunc // requestID → cancel func
+	mu            sync.Mutex
 }

-func (c *Client) sendJSON(v any) error {
+// SendJSON 向客户端发送 JSON 消息（公开以便 errors 包调用）。
+func (c *Client) SendJSON(v any) error {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 	return c.conn.WriteJSON(v)
 }

+// WSClient 实现 orchestrator.Sender 接口，将消息推送到 WebSocket 连接。
+type WSClient struct {
+	client    *Client
+	requestID string
+}
+
+// SendSTTResult 发送语音识别结果。
+func (w *WSClient) SendSTTResult(result models.WsSTTResult) error {
+	result.RequestID = w.requestID
+	return w.client.SendJSON(result)
+}
+
+// SendLLMChunk 发送 LLM 流式文本增量。
+func (w *WSClient) SendLLMChunk(chunk models.WsLLMChunk) error {
+	chunk.RequestID = w.requestID
+	return w.client.SendJSON(chunk)
+}
+
+// SendLLMDone 发送 LLM 流结束信号。
+func (w *WSClient) SendLLMDone(done models.WsLLMDone) error {
+	done.RequestID = w.requestID
+	return w.client.SendJSON(done)
+}
+
+// SendTTSAudio 发送 TTS 音频数据。
+func (w *WSClient) SendTTSAudio(audio models.WsTTSAudio) error {
+	audio.RequestID = w.requestID
+	return w.client.SendJSON(audio)
+}
+
+// SendError 发送错误消息。
+func (w *WSClient) SendError(err models.WsError) error {
+	err.RequestID = w.requestID
+	return w.client.SendJSON(err)
+}
+
 // ServeWS 处理 WebSocket 升级请求。
-func ServeWS(c *gin.Context) {
+func ServeWS(sessionMgr session.Manager, orch orchestrator.Orchestrator) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		serveWS(c, sessionMgr, orch)
+	}
+}
+
+func serveWS(c *gin.Context, sessionMgr session.Manager, orch orchestrator.Orchestrator) {
 	conn, err := upgrader.Upgrade(c.Writer, c.Request, nil)
 	if err != nil {
-		log.Printf("websocket upgrade failed: %v", err)
+		logger.Log.Errorw("websocket upgrade failed", "error", err)
 		return
 	}
 	defer conn.Close()

-	sessionID := uuid.New().String()
-	client := &Client{conn: conn, sessionID: sessionID}
+	// 创建会话
+	sessionID, err := sessionMgr.Create(context.Background(), models.DefaultConfig())
+	if err != nil {
+		logger.Log.Errorw("create session failed", "error", err)
+		return
+	}
+
+	client := &Client{
+		conn:         conn,
+		sessionID:    sessionID,
+		sessionMgr:   sessionMgr,
+		orchestrator: orch,
+		cancelFuncs:  make(map[string]context.CancelFunc),
+	}

 	// 发送 connected 消息
-	_ = client.sendJSON(models.WsConnected{
+	_ = client.SendJSON(models.WsConnected{
 		Type:          "connected",
 		SessionID:     sessionID,
 		ServerVersion: "0.1.0",
 	})
-	log.Printf("client connected: session=%s", sessionID)
+	logger.Log.Infow("client connected", "session", sessionID)

 	// 心跳检测
 	lastPong := time.Now()
@@ -67,7 +128,7 @@ func ServeWS(c *gin.Context) {
 			select {
 			case <-ticker.C:
 				if time.Since(lastPong) > 60*time.Second {
-					log.Printf("heartbeat timeout: session=%s", sessionID)
+					logger.Log.Warnw("heartbeat timeout", "session", sessionID)
 					conn.Close()
 					return
 				}
@@ -82,7 +143,7 @@ func ServeWS(c *gin.Context) {
 		_, message, err := conn.ReadMessage()
 		if err != nil {
 			if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseNormalClosure) {
-				log.Printf("ws read error: %v", err)
+				logger.Log.Warnw("ws read error", "error", err)
 			}
 			break
 		}
@@ -92,51 +153,96 @@ func ServeWS(c *gin.Context) {
 			Type string `json:"type"`
 		}
 		if err := json.Unmarshal(message, &envelope); err != nil {
-			_ = client.sendJSON(models.WsError{
-				Type:    "error",
-				Code:    "INVALID_MESSAGE",
-				Message: "invalid JSON",
-			})
+			errors.SendWSError(client, errors.CodeInvalidMessage, "", err)
 			continue
 		}

 		switch envelope.Type {
 		case "ping":
-			_ = client.sendJSON(models.WsPong{Type: "pong"})
+			_ = client.SendJSON(models.WsPong{Type: "pong"})

 		case "query":
 			var msg models.WsQuery
 			if err := json.Unmarshal(message, &msg); err != nil {
-				_ = client.sendJSON(models.WsError{
-					Type:      "error",
-					Code:      "INVALID_MESSAGE",
-					Message:   "invalid query message",
-					RequestID: msg.RequestID,
-				})
+				errors.SendWSError(client, errors.CodeInvalidMessage, msg.RequestID, err)
 				continue
 			}
-			log.Printf("query received: session=%s request=%s", sessionID, msg.RequestID)
-			// TODO: 调用 AI 编排流程（STT → LLM → TTS）
+			logger.Log.Infow("query received", "session", sessionID, "request", msg.RequestID)
+
+			// 刷新会话 TTL
+			if err := client.sessionMgr.Touch(context.Background(), sessionID); err != nil {
+				logger.Log.Warnw("touch session failed", "session", sessionID, "error", err)
+			}
+
+			// 标记活跃请求
+			if err := client.sessionMgr.SetActiveRequest(context.Background(), sessionID, msg.RequestID); err != nil {
+				logger.Log.Warnw("set active request failed", "session", sessionID, "error", err)
+			}
+
+			// 获取对话历史
+			history, _ := client.sessionMgr.GetHistory(context.Background(), sessionID, 20)
+
+			// 创建可取消的 context
+			ctx, cancel := context.WithCancel(context.Background())
+			client.mu.Lock()
+			client.cancelFuncs[msg.RequestID] = cancel
+			client.mu.Unlock()
+
+			// 创建 sender
+			sender := &WSClient{client: client, requestID: msg.RequestID}
+
+			// 启动 orchestrator 处理 goroutine
+			go func() {
+				defer func() {
+					// 清理 cancel func
+					client.mu.Lock()
+					delete(client.cancelFuncs, msg.RequestID)
+					client.mu.Unlock()
+					cancel()
+					// 清除活跃请求
+					_ = client.sessionMgr.ClearActiveRequest(context.Background(), sessionID)
+				}()
+
+				if err := client.orchestrator.ProcessQuery(ctx, sessionID, msg, history, sender); err != nil {
+					logger.Log.Errorw("process query failed", "session", sessionID, "request", msg.RequestID, "error", err)
+				}
+			}()

 		case "config":
 			var msg models.WsConfig
 			if err := json.Unmarshal(message, &msg); err != nil {
-				_ = client.sendJSON(models.WsError{
-					Type:    "error",
-					Code:    "INVALID_MESSAGE",
-					Message: "invalid config message",
-				})
+				errors.SendWSError(client, errors.CodeInvalidMessage, "", err)
 				continue
 			}
-			log.Printf("config update: session=%s", sessionID)
-			// TODO: 更新会话配置
+
+			patch := models.SessionConfigPatch{
+				TTSEnabled:  msg.Payload.TTSEnabled,
+				DetailLevel: msg.Payload.DetailLevel,
+				Language:    msg.Payload.Language,
+			}
+			if err := client.sessionMgr.UpdateConfig(context.Background(), sessionID, patch); err != nil {
+				errors.SendWSError(client, errors.CodeInternalError, "", err)
+				continue
+			}
+			logger.Log.Infow("config updated", "session", sessionID)

 		case "interrupt":
-			log.Printf("interrupt received: session=%s", sessionID)
-			// TODO: 中断当前 AI 响应
+			logger.Log.Infow("interrupt received", "session", sessionID)
+
+			// 获取活跃请求 ID 并取消
+			reqID, _ := client.sessionMgr.GetActiveRequestID(context.Background(), sessionID)
+			if reqID != "" {
+				client.mu.Lock()
+				if cancel, ok := client.cancelFuncs[reqID]; ok {
+					cancel()
+					delete(client.cancelFuncs, reqID)
+				}
+				client.mu.Unlock()
+				_ = client.sessionMgr.ClearActiveRequest(context.Background(), sessionID)
+			}

 		default:
-			_ = client.sendJSON(models.WsError{
+			_ = client.SendJSON(models.WsError{
 				Type:    "error",
 				Code:    "INVALID_MESSAGE",
 				Message: "unknown message type: " + envelope.Type,
@@ -145,5 +251,16 @@ func ServeWS(c *gin.Context) {
 	}

 	close(done)
-	log.Printf("client disconnected: session=%s", sessionID)
+
+	// 取消所有活跃请求
+	client.mu.Lock()
+	for reqID, cancel := range client.cancelFuncs {
+		logger.Log.Infow("canceling active request on disconnect", "session", sessionID, "request", reqID)
+		cancel()
+	}
+	client.cancelFuncs = make(map[string]context.CancelFunc)
+	client.mu.Unlock()
+
+	// 断开连接时不销毁会话，让其自然过期（支持重连恢复）
+	logger.Log.Infow("client disconnected", "session", sessionID)
 }
--- a/backend/internal/ws/handler_test.go
+++ b/backend/internal/ws/handler_test.go
@@ -0,0 +1,563 @@
+package ws
+
+import (
+	"encoding/base64"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/gin-gonic/gin"
+	"github.com/gorilla/websocket"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"context"
+
+	"github.com/hhs/camtalk/internal/logger"
+	"github.com/hhs/camtalk/internal/models"
+	"github.com/hhs/camtalk/internal/orchestrator"
+	"github.com/hhs/camtalk/internal/session"
+)
+
+func init() {
+	logger.Init("debug", "console")
+	gin.SetMode(gin.TestMode)
+}
+
+// --- Mock Orchestrator ---
+
+// MockOrchestrator 实现 orchestrator.Orchestrator 接口，
+// 模拟完整的 STT → LLM → TTS 管道，通过 sender 推送消息。
+type MockOrchestrator struct {
+	// STTResult 模拟的语音识别结果
+	STTResult string
+	// LLMDeltas 模拟的 LLM 流式输出
+	LLMDeltas []string
+	// TTSAudios 模拟的 TTS 音频数据（每项一个 base64 编码的 MP3 片段）
+	TTSAudios []string
+	// Err 如果非 nil，ProcessQuery 直接返回此错误
+	Err error
+	// Delay 每个消息之间的延迟（用于 interrupt 测试）
+	Delay time.Duration
+}
+
+func (m *MockOrchestrator) ProcessQuery(
+	ctx context.Context,
+	sessionID string,
+	req models.WsQuery,
+	history []models.Message,
+	sender orchestrator.Sender,
+) error {
+	if m.Err != nil {
+		sender.SendError(models.WsError{
+			Type:      "error",
+			RequestID: req.RequestID,
+			Code:      "INTERNAL_ERROR",
+			Message:   m.Err.Error(),
+		})
+		return m.Err
+	}
+
+	// Step 1: 发送 STT 结果
+	if m.STTResult != "" {
+		_ = sender.SendSTTResult(models.WsSTTResult{
+			Type:      "stt_result",
+			RequestID: req.RequestID,
+			Text:      m.STTResult,
+			IsFinal:   true,
+		})
+	}
+	if m.Delay > 0 {
+		select {
+		case <-ctx.Done():
+			return nil // 中断视为正常完成
+		case <-time.After(m.Delay):
+		}
+	}
+
+	// Step 2: 发送 LLM chunks
+	var fullText strings.Builder
+	for _, delta := range m.LLMDeltas {
+		select {
+		case <-ctx.Done():
+			return nil // 中断视为正常完成
+		default:
+		}
+		fullText.WriteString(delta)
+		_ = sender.SendLLMChunk(models.WsLLMChunk{
+			Type:      "llm_chunk",
+			RequestID: req.RequestID,
+			Delta:     delta,
+			Role:      "assistant",
+		})
+		if m.Delay > 0 {
+			select {
+			case <-ctx.Done():
+				return nil // 中断视为正常完成
+			case <-time.After(m.Delay):
+			}
+		}
+	}
+
+	// Step 3: 发送 TTS 音频
+	for i, audio := range m.TTSAudios {
+		select {
+		case <-ctx.Done():
+			return nil // 中断视为正常完成
+		default:
+		}
+		isLast := i == len(m.TTSAudios)-1
+		_ = sender.SendTTSAudio(models.WsTTSAudio{
+			Type:      "tts_audio",
+			RequestID: req.RequestID,
+			Audio:     audio,
+			MimeType:  "audio/mp3",
+			IsLast:    isLast,
+		})
+	}
+
+	// Step 4: 发送 llm_done
+	_ = sender.SendLLMDone(models.WsLLMDone{
+		Type:      "llm_done",
+		RequestID: req.RequestID,
+		FullText:  fullText.String(),
+		Model:     "gpt-4o",
+		LatencyMs: 100,
+	})
+
+	return nil
+}
+
+// --- 测试辅助函数 ---
+
+// setupTestServer 创建测试用 Gin 服务器和 WebSocket URL。
+func setupTestServer(t *testing.T, orch orchestrator.Orchestrator) (*httptest.Server, string) {
+	t.Helper()
+
+	sessionMgr := session.NewMemoryManager(5*time.Minute, 20)
+	t.Cleanup(func() { sessionMgr.Stop() })
+
+	r := gin.New()
+	r.GET("/ws", ServeWS(sessionMgr, orch))
+
+	srv := httptest.NewServer(r)
+
+	// 构造 WebSocket URL
+	wsURL := "ws" + strings.TrimPrefix(srv.URL, "http") + "/ws"
+
+	return srv, wsURL
+}
+
+// connectWS 建立 WebSocket 连接并返回 conn。
+func connectWS(t *testing.T, wsURL string) *websocket.Conn {
+	t.Helper()
+
+	conn, _, err := websocket.DefaultDialer.Dial(wsURL, nil)
+	require.NoError(t, err, "WebSocket 连接失败")
+	t.Cleanup(func() { conn.Close() })
+	return conn
+}
+
+// readJSON 从 WebSocket 读取一条 JSON 消息。
+func readJSON(t *testing.T, conn *websocket.Conn) map[string]any {
+	t.Helper()
+
+	conn.SetReadDeadline(time.Now().Add(5 * time.Second))
+	var msg map[string]any
+	err := conn.ReadJSON(&msg)
+	require.NoError(t, err, "读取 WebSocket 消息失败")
+	return msg
+}
+
+// --- 测试用例 ---
+
+// TestWS_Connected 验证连接建立后收到 connected 消息。
+func TestWS_Connected(t *testing.T) {
+	srv, wsURL := setupTestServer(t, &MockOrchestrator{})
+	defer srv.Close()
+
+	conn := connectWS(t, wsURL)
+
+	msg := readJSON(t, conn)
+	assert.Equal(t, "connected", msg["type"])
+	assert.NotEmpty(t, msg["session_id"])
+	assert.Equal(t, "0.1.0", msg["server_version"])
+}
+
+// TestWS_PingPong 验证 ping/pong 心跳。
+func TestWS_PingPong(t *testing.T) {
+	srv, wsURL := setupTestServer(t, &MockOrchestrator{})
+	defer srv.Close()
+
+	conn := connectWS(t, wsURL)
+
+	// 读取 connected 消息
+	_ = readJSON(t, conn)
+
+	// 发送 ping
+	err := conn.WriteJSON(map[string]string{"type": "ping"})
+	require.NoError(t, err)
+
+	// 读取 pong
+	msg := readJSON(t, conn)
+	assert.Equal(t, "pong", msg["type"])
+}
+
+// TestWS_QueryFullFlow 验证完整的 query → stt_result → llm_chunk → tts_audio → llm_done 流程。
+func TestWS_QueryFullFlow(t *testing.T) {
+	audioB64 := base64.StdEncoding.EncodeToString([]byte("fake-audio-data"))
+	imageB64 := base64.StdEncoding.EncodeToString([]byte("fake-image-data"))
+
+	mock := &MockOrchestrator{
+		STTResult:  "你好，世界",
+		LLMDeltas:  []string{"你好", "，世界！"},
+		TTSAudios:  []string{base64.StdEncoding.EncodeToString([]byte("mp3-data-1")), base64.StdEncoding.EncodeToString([]byte("mp3-data-2"))},
+	}
+
+	srv, wsURL := setupTestServer(t, mock)
+	defer srv.Close()
+
+	conn := connectWS(t, wsURL)
+
+	// 1. 读取 connected
+	connected := readJSON(t, conn)
+	assert.Equal(t, "connected", connected["type"])
+	sessionID := connected["session_id"].(string)
+	assert.NotEmpty(t, sessionID)
+
+	// 2. 发送 query
+	queryMsg := models.WsQuery{
+		Type:      "query",
+		RequestID: "req-test-001",
+		Image:     imageB64,
+		Audio:     audioB64,
+		MimeType:  "audio/pcm",
+	}
+	err := conn.WriteJSON(queryMsg)
+	require.NoError(t, err)
+
+	// 3. 读取 stt_result
+	sttResult := readJSON(t, conn)
+	assert.Equal(t, "stt_result", sttResult["type"])
+	assert.Equal(t, "req-test-001", sttResult["request_id"])
+	assert.Equal(t, "你好，世界", sttResult["text"])
+	assert.Equal(t, true, sttResult["is_final"])
+
+	// 4. 读取 llm_chunk 消息
+	chunk1 := readJSON(t, conn)
+	assert.Equal(t, "llm_chunk", chunk1["type"])
+	assert.Equal(t, "req-test-001", chunk1["request_id"])
+	assert.Equal(t, "你好", chunk1["delta"])
+	assert.Equal(t, "assistant", chunk1["role"])
+
+	chunk2 := readJSON(t, conn)
+	assert.Equal(t, "llm_chunk", chunk2["type"])
+	assert.Equal(t, "，世界！", chunk2["delta"])
+
+	// 5. 读取 tts_audio 消息
+	tts1 := readJSON(t, conn)
+	assert.Equal(t, "tts_audio", tts1["type"])
+	assert.Equal(t, "req-test-001", tts1["request_id"])
+	assert.NotEmpty(t, tts1["audio"])
+	assert.Equal(t, "audio/mp3", tts1["mime_type"])
+	assert.Equal(t, false, tts1["is_last"])
+
+	tts2 := readJSON(t, conn)
+	assert.Equal(t, "tts_audio", tts2["type"])
+	assert.Equal(t, true, tts2["is_last"])
+
+	// 6. 读取 llm_done
+	llmDone := readJSON(t, conn)
+	assert.Equal(t, "llm_done", llmDone["type"])
+	assert.Equal(t, "req-test-001", llmDone["request_id"])
+	assert.Equal(t, "你好，世界！", llmDone["full_text"])
+	assert.Equal(t, "gpt-4o", llmDone["model"])
+	assert.NotNil(t, llmDone["latency_ms"])
+}
+
+// TestWS_QuerySTTOnly 验证只有 STT 结果、无 LLM 输出的场景。
+func TestWS_QuerySTTOnly(t *testing.T) {
+	audioB64 := base64.StdEncoding.EncodeToString([]byte("audio"))
+
+	mock := &MockOrchestrator{
+		STTResult: "测试语音",
+		// LLMDeltas 为空 → 不发送 llm_chunk
+		// TTSAudios 为空 → 不发送 tts_audio
+	}
+
+	srv, wsURL := setupTestServer(t, mock)
+	defer srv.Close()
+
+	conn := connectWS(t, wsURL)
+	_ = readJSON(t, conn) // connected
+
+	err := conn.WriteJSON(models.WsQuery{
+		Type:      "query",
+		RequestID: "req-stt-only",
+		Audio:     audioB64,
+	})
+	require.NoError(t, err)
+
+	// 应收到 stt_result
+	stt := readJSON(t, conn)
+	assert.Equal(t, "stt_result", stt["type"])
+	assert.Equal(t, "测试语音", stt["text"])
+
+	// 应收到 llm_done（即使没有 chunk）
+	done := readJSON(t, conn)
+	assert.Equal(t, "llm_done", done["type"])
+	assert.Equal(t, "", done["full_text"])
+}
+
+// TestWS_UnknownMessageType 验证未知消息类型返回 error。
+func TestWS_UnknownMessageType(t *testing.T) {
+	srv, wsURL := setupTestServer(t, &MockOrchestrator{})
+	defer srv.Close()
+
+	conn := connectWS(t, wsURL)
+	_ = readJSON(t, conn) // connected
+
+	err := conn.WriteJSON(map[string]string{"type": "unknown_type"})
+	require.NoError(t, err)
+
+ errMsg := readJSON(t, conn)
+	assert.Equal(t, "error", errMsg["type"])
+	assert.Equal(t, "INVALID_MESSAGE", errMsg["code"])
+	assert.Contains(t, errMsg["message"], "unknown message type")
+}
+
+// TestWS_InvalidJSON 验证无效 JSON 返回 error。
+func TestWS_InvalidJSON(t *testing.T) {
+	srv, wsURL := setupTestServer(t, &MockOrchestrator{})
+	defer srv.Close()
+
+	conn := connectWS(t, wsURL)
+	_ = readJSON(t, conn) // connected
+
+	err := conn.WriteMessage(websocket.TextMessage, []byte("not-json"))
+	require.NoError(t, err)
+
+	errMsg := readJSON(t, conn)
+	assert.Equal(t, "error", errMsg["type"])
+	assert.Equal(t, "INVALID_MESSAGE", errMsg["code"])
+}
+
+// TestWS_MultipleQueries 验证同一连接上可以发送多次 query。
+func TestWS_MultipleQueries(t *testing.T) {
+	mock := &MockOrchestrator{
+		STTResult: "识别结果",
+		LLMDeltas: []string{"回复"},
+	}
+
+	srv, wsURL := setupTestServer(t, mock)
+	defer srv.Close()
+
+	conn := connectWS(t, wsURL)
+	_ = readJSON(t, conn) // connected
+
+	audioB64 := base64.StdEncoding.EncodeToString([]byte("audio"))
+
+	for i := 0; i < 3; i++ {
+		reqID := "req-multi-" + string(rune('0'+i))
+		err := conn.WriteJSON(models.WsQuery{
+			Type:      "query",
+			RequestID: reqID,
+			Audio:     audioB64,
+		})
+		require.NoError(t, err)
+
+		// 每次应收到完整的响应序列
+		stt := readJSON(t, conn)
+		assert.Equal(t, "stt_result", stt["type"], "第 %d 次 query", i+1)
+
+		chunk := readJSON(t, conn)
+		assert.Equal(t, "llm_chunk", chunk["type"], "第 %d 次 query", i+1)
+
+		done := readJSON(t, conn)
+		assert.Equal(t, "llm_done", done["type"], "第 %d 次 query", i+1)
+	}
+}
+
+// TestWS_Interrupt 验证 interrupt 取消正在进行的请求。
+func TestWS_Interrupt(t *testing.T) {
+	// 使用较长延迟模拟慢请求
+	mock := &MockOrchestrator{
+		STTResult: "识别文本",
+		LLMDeltas: []string{"第一句", "第二句", "第三句", "第四句", "第五句"},
+		Delay:     200 * time.Millisecond,
+	}
+
+	srv, wsURL := setupTestServer(t, mock)
+	defer srv.Close()
+
+	conn := connectWS(t, wsURL)
+	_ = readJSON(t, conn) // connected
+
+	audioB64 := base64.StdEncoding.EncodeToString([]byte("audio"))
+
+	// 发送 query
+	err := conn.WriteJSON(models.WsQuery{
+		Type:      "query",
+		RequestID: "req-interrupt",
+		Audio:     audioB64,
+	})
+	require.NoError(t, err)
+
+	// 收到 stt_result
+	stt := readJSON(t, conn)
+	assert.Equal(t, "stt_result", stt["type"])
+
+	// 收到第一个 llm_chunk
+	chunk1 := readJSON(t, conn)
+	assert.Equal(t, "llm_chunk", chunk1["type"])
+
+	// 发送 interrupt
+	err = conn.WriteJSON(map[string]string{"type": "interrupt"})
+	require.NoError(t, err)
+
+	// 等待 interrupt 生效
+	time.Sleep(500 * time.Millisecond)
+
+	// 验证连接仍然存活（可以发 ping 收 pong）
+	require.NoError(t, conn.WriteJSON(map[string]string{"type": "ping"}))
+
+	var pong map[string]any
+	conn.SetReadDeadline(time.Now().Add(5 * time.Second))
+	require.NoError(t, conn.ReadJSON(&pong), "interrupt 后连接应仍存活")
+	assert.Equal(t, "pong", pong["type"])
+}
+
+// TestWS_DisconnectCleanup 验证断开连接时清理资源。
+func TestWS_DisconnectCleanup(t *testing.T) {
+	// 使用较长延迟模拟慢请求
+	mock := &MockOrchestrator{
+		STTResult: "识别文本",
+		LLMDeltas: []string{"长回复第一部分", "长回复第二部分"},
+		Delay:     500 * time.Millisecond,
+	}
+
+	srv, wsURL := setupTestServer(t, mock)
+	defer srv.Close()
+
+	conn := connectWS(t, wsURL)
+	_ = readJSON(t, conn) // connected
+
+	audioB64 := base64.StdEncoding.EncodeToString([]byte("audio"))
+
+	// 发送 query
+	err := conn.WriteJSON(models.WsQuery{
+		Type:      "query",
+		RequestID: "req-disconnect",
+		Audio:     audioB64,
+	})
+	require.NoError(t, err)
+
+	// 收到 stt_result
+	stt := readJSON(t, conn)
+	assert.Equal(t, "stt_result", stt["type"])
+
+	// 关闭连接（模拟客户端断开）
+	conn.Close()
+
+	// 等待一小段时间让服务器处理断开
+	time.Sleep(300 * time.Millisecond)
+
+	// 如果没有 panic 或 goroutine 泄漏，测试通过
+	// （Go test 的 -race 检测器会捕获数据竞争）
+}
+
+// TestWS_SessionCreated 验证每次连接都创建新会话。
+func TestWS_SessionCreated(t *testing.T) {
+	srv, wsURL := setupTestServer(t, &MockOrchestrator{})
+	defer srv.Close()
+
+	// 第一次连接
+	conn1 := connectWS(t, wsURL)
+	msg1 := readJSON(t, conn1)
+	sid1 := msg1["session_id"].(string)
+	conn1.Close()
+
+	time.Sleep(100 * time.Millisecond)
+
+	// 第二次连接
+	conn2 := connectWS(t, wsURL)
+	sid2 := readJSON(t, conn2)["session_id"].(string)
+
+	assert.NotEmpty(t, sid1)
+	assert.NotEmpty(t, sid2)
+	assert.NotEqual(t, sid1, sid2, "两次连接应创建不同的会话")
+}
+
+// TestWS_QueryWithoutImage 验证不带图片的 query。
+func TestWS_QueryWithoutImage(t *testing.T) {
+	mock := &MockOrchestrator{
+		STTResult: "纯语音输入",
+		LLMDeltas: []string{"收到"},
+	}
+
+	srv, wsURL := setupTestServer(t, mock)
+	defer srv.Close()
+
+	conn := connectWS(t, wsURL)
+	_ = readJSON(t, conn) // connected
+
+	audioB64 := base64.StdEncoding.EncodeToString([]byte("audio"))
+
+	err := conn.WriteJSON(models.WsQuery{
+		Type:      "query",
+		RequestID: "req-no-image",
+		Audio:     audioB64,
+		// Image 为空
+	})
+	require.NoError(t, err)
+
+	stt := readJSON(t, conn)
+	assert.Equal(t, "stt_result", stt["type"])
+	assert.Equal(t, "纯语音输入", stt["text"])
+
+	chunk := readJSON(t, conn)
+	assert.Equal(t, "llm_chunk", chunk["type"])
+
+	done := readJSON(t, conn)
+	assert.Equal(t, "llm_done", done["type"])
+}
+
+// TestWS_QueryWithTTSDisabled 验证 TTS 未启用时不应收到 tts_audio。
+func TestWS_QueryWithTTSDisabled(t *testing.T) {
+	// MockOrchestrator 的 TTSAudios 为空 → 不发送 tts_audio
+	mock := &MockOrchestrator{
+		STTResult: "语音",
+		LLMDeltas: []string{"回复"},
+		// TTSAudios 留空
+	}
+
+	srv, wsURL := setupTestServer(t, mock)
+	defer srv.Close()
+
+	conn := connectWS(t, wsURL)
+	_ = readJSON(t, conn) // connected
+
+	audioB64 := base64.StdEncoding.EncodeToString([]byte("audio"))
+
+	err := conn.WriteJSON(models.WsQuery{
+		Type:      "query",
+		RequestID: "req-no-tts",
+		Audio:     audioB64,
+	})
+	require.NoError(t, err)
+
+	stt := readJSON(t, conn)
+	assert.Equal(t, "stt_result", stt["type"])
+
+	chunk := readJSON(t, conn)
+	assert.Equal(t, "llm_chunk", chunk["type"])
+
+	done := readJSON(t, conn)
+	assert.Equal(t, "llm_done", done["type"])
+
+	// 不应有 tts_audio 消息；设置短超时验证
+	conn.SetReadDeadline(time.Now().Add(200 * time.Millisecond))
+	var extra map[string]any
+	err = conn.ReadJSON(&extra)
+	assert.Error(t, err, "不应有额外消息")
+}
--- a/docs/02-系统架构.md
+++ b/docs/02-系统架构.md
@@ -213,11 +213,73 @@ CREATE TABLE usage_daily (
 ## 部署架构

 ```
-CDN（静态资源） ← 用户浏览器
-Nginx 负载均衡（sticky session for WebSocket）
-  ├── Gateway-1 ──→ Redis
-  ├── Gateway-2 ──→ Redis
-  └── Gateway-N ──→ AI Services（外部 API）
+用户浏览器
+    ↓
+Nginx（同源反代 + 负载均衡）
+  ├── /            → 前端静态资源（CDN 或本地 dist）
+  ├── /api/*       → Go Gateway（REST API）
+  └── /ws          → Go Gateway（WebSocket）
+        ├── Gateway-1 ──→ Redis
+        ├── Gateway-2 ──→ Redis
+        └── Gateway-N ──→ AI Services（外部 API）
 ```

-WebSocket 是长连接，Nginx 需要配置 `proxy_set_header Upgrade` 和 sticky session，确保同一用户的请求始终路由到同一个 Gateway 实例。
+**跨域策略**：Nginx 将前端和后端统一到同一域名下，浏览器无跨域问题。
+
+### Nginx 配置
+
+```nginx
+server {
+    listen 80;
+    server_name camtalk.example.com;
+
+    # 前端静态资源
+    location / {
+        root /var/www/camtalk/dist;
+        try_files $uri $uri/ /index.html;
+    }
+
+    # REST API 反代
+    location /api/ {
+        proxy_pass http://127.0.0.1:8080;
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+    }
+
+    # WebSocket 反代
+    location /ws {
+        proxy_pass http://127.0.0.1:8080;
+        proxy_http_version 1.1;
+        proxy_set_header Upgrade $http_upgrade;
+        proxy_set_header Connection "upgrade";
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_read_timeout 86400s;   # 长连接超时 24h
+        proxy_send_timeout 86400s;
+    }
+}
+```
+
+> WebSocket 是长连接，Nginx 必须配置 `Upgrade` 和 `Connection` 头。`proxy_read_timeout` 需要覆盖心跳间隔（客户端 30s ping），否则 Nginx 会主动断开空闲连接。
+
+### 开发环境（Vite proxy）
+
+开发时前端（Vite :5173）和后端（Gin :8080）不同端口，用 Vite 内置代理解决跨域：
+
+```typescript
+// frontend/vite.config.ts
+export default defineConfig({
+  plugins: [react()],
+  server: {
+    proxy: {
+      "/api": "http://localhost:8080",
+      "/ws": {
+        target: "ws://localhost:8080",
+        ws: true,
+      },
+    },
+  },
+});
+```
+
+前端代码中 WebSocket 地址改为相对路径 `ws://localhost:5173/ws`，Vite 自动代理到后端。部署时 Nginx 同理，前端无需区分开发/生产地址。
--- a/docs/03-接口文档.md
+++ b/docs/03-接口文档.md
@@ -256,7 +256,6 @@ POST /api/sessions
 Content-Type: application/json

 {
-  "user_id": "optional-user-id",
  "config": {
    "tts_enabled": true,
    "detail_level": "low",
@@ -301,28 +300,18 @@ Go 网关内部与外部 AI 服务（Deepgram STT、GPT-4o、OpenAI TTS）的调
 语音识别：接收前端采集的音频，返回识别文本。

 ```go
-// STTService 语音识别服务契约。
-type STTService interface {
+// Service 语音识别服务契约。
+type Service interface {
    // Recognize 识别一段完整音频，返回最终文本。
-    Recognize(ctx context.Context, audio []byte, opts STTOptions) (string, error)
-
-    // RecognizeStream 流式识别（边说边识别，可选实现）。
-    // audioStream 持续接收音频片段，返回的 channel 持续输出中间结果。
-    RecognizeStream(ctx context.Context, audioStream <-chan []byte, opts STTOptions) (<-chan STTPartial, error)
+    Recognize(ctx context.Context, audio []byte, opts Options) (string, error)
 }

-// STTOptions 语音识别参数。
-type STTOptions struct {
+// Options 语音识别参数。
+type Options struct {
    Encoding   string // "pcm_s16le" — 前端 VAD 输出格式
    SampleRate int    // 16000 — 前端麦克风采样率
    Language   string // "zh-CN"
 }
-
-// STTPartial 流式识别的中间/最终结果。
-type STTPartial struct {
-    Text    string
-    IsFinal bool
-}
 ```

 **Deepgram 接入约定**：
@@ -336,23 +325,23 @@ type STTPartial struct {
 多模态推理：接收图像 + 文本 + 对话历史，流式返回回复。

 ```go
-// LLMService 多模态大模型服务契约。
-type LLMService interface {
+// Service 多模态大模型服务契约。
+type Service interface {
    // ChatStream 流式推理，返回增量文本的 channel。
    // 调用方必须消费 channel 直到 Done=true，否则需 cancel ctx 以释放连接。
-    ChatStream(ctx context.Context, req LLMRequest) (<-chan LLMChunk, error)
+    ChatStream(ctx context.Context, req Request) (<-chan Chunk, error)
 }

-// LLMRequest 推理请求。
-type LLMRequest struct {
-    Image    []byte    // JPEG 图片（已从 Base64 解码）
-    Text     string    // 用户语音识别后的文本
-    History  []Message // 最近 N 轮对话历史
-    Language string    // "zh-CN"
+// Request 推理请求。
+type Request struct {
+    Image    []byte            // JPEG 图片（已从 Base64 解码）
+    Text     string            // 用户语音识别后的文本
+    History  []models.Message  // 最近 N 轮对话历史
+    Language string            // "zh-CN"
 }

-// LLMChunk 流式推理的一个增量片段。
-type LLMChunk struct {
+// Chunk 流式推理的一个增量片段。
+type Chunk struct {
    Delta      string       // 增量文本
    Done       bool         // 是否结束
    TokensUsed *TokenUsage  // 仅 Done=true 时有值
@@ -388,24 +377,24 @@ user: [图片 + 用户语音文本]
 语音合成：接收文本流，输出音频 chunk 流。

 ```go
-// TTSService 语音合成服务契约。
-type TTSService interface {
+// Service 语音合成服务契约。
+type Service interface {
    // SynthesizeStream 流式合成。
    // textStream 接收句子级文本（由 Orchestrator 的句子切分器产出），
    // 返回的 channel 持续输出 MP3 音频 chunk。
-    SynthesizeStream(ctx context.Context, textStream <-chan string, opts TTSOptions) (<-chan TTSChunk, error)
+    SynthesizeStream(ctx context.Context, textStream <-chan string, opts Options) (<-chan Chunk, error)
 }

-// TTSOptions 合成参数。
-type TTSOptions struct {
+// Options 合成参数。
+type Options struct {
    Voice      string  // "alloy" | "nova" | "shimmer" | ...
    Speed      float64 // 1.0 为正常语速
    OutputFmt  string  // "mp3" — 固定使用 MP3，浏览器原生支持
    SampleRate int     // 24000
 }

-// TTSChunk 一个音频片段。
-type TTSChunk struct {
+// Chunk 一个音频片段。
+type Chunk struct {
    Audio  []byte // MP3 音频数据（未 Base64 编码，由发送层编码）
    IsLast bool   // 是否为最后一片
 }
@@ -446,73 +435,32 @@ LLM 流式输出:  "这" "是一" "朵红色" "的花。" "它看起" "来很美
 ### Orchestrator 接口

 ```go
-// Orchestrator AI 编排器，协调 STT → LLM → TTS 全链路。
-type Orchestrator struct {
-    stt  STTService
-    llm  LLMService
-    tts  TTSService
+// Orchestrator AI 编排器接口。
+type Orchestrator interface {
+    // ProcessQuery 处理一次完整的视觉对话请求。
+    // 通过 sender 向前端实时推送 stt_result、llm_chunk、llm_done、tts_audio 消息。
+    ProcessQuery(ctx context.Context, sessionID string, req models.WsQuery,
+        history []models.Message, sender Sender) error
 }

-// ProcessQuery 处理一次完整的视觉对话请求。
-// 通过 client 向前端实时推送 stt_result、llm_chunk、llm_done、tts_audio 消息。
-func (o *Orchestrator) ProcessQuery(ctx context.Context, client MessageSender, req *QueryRequest) {
-    ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
-    defer cancel()
-
-    // Step 1: STT — 识别用户语音
-    text, err := o.stt.Recognize(ctx, req.Audio, STTOptions{
-        Encoding: "pcm_s16le", SampleRate: 16000, Language: "zh-CN",
-    })
-    if err != nil {
-        client.SendError(req.RequestID, "STT_ERROR", err.Error())
-        return
-    }
-    client.SendSTTResult(req.RequestID, text, true)
-
-    // Step 2: LLM 流式输出 + 句子切分
-    llmStream, _ := o.llm.ChatStream(ctx, LLMRequest{
-        Image: req.Image, Text: text, Language: "zh-CN",
-    })
-
-    sentenceCh := make(chan string, 4)
-    go func() {
-        defer close(sentenceCh)
-        var buf strings.Builder
-        var fullText strings.Builder
-        for chunk := range llmStream {
-            // 即时推送文字给客户端（逐 token 显示）
-            client.SendLLMChunk(req.RequestID, chunk.Delta)
-            fullText.WriteString(chunk.Delta)
-            buf.WriteString(chunk.Delta)
-            // 遇到句子边界就吐出
-            if isSentenceEnd(chunk.Delta) {
-                sentenceCh <- buf.String()
-                buf.Reset()
-            }
-        }
-        // 最后一段不足一句的也吐出
-        if buf.Len() > 0 {
-            sentenceCh <- buf.String()
-        }
-        // 推送 llm_done
-        client.SendLLMDone(req.RequestID, fullText.String(), chunk.TokensUsed, chunk.Model)
-    }()
-
-    // Step 3: TTS 并行消费句子流
-    ttsStream, _ := o.tts.SynthesizeStream(ctx, sentenceCh, TTSOptions{
-        Voice: "alloy", OutputFmt: "mp3", SampleRate: 24000,
-    })
-    for chunk := range ttsStream {
-        client.SendTTSAudio(req.RequestID, chunk.Audio, chunk.IsLast)
-    }
-}
-
-// isSentenceEnd 判断 delta 中是否包含句子结束标志。
-func isSentenceEnd(delta string) bool {
-    return strings.ContainsAny(delta, "。！？\n.!?\n")
+// Sender 抽象 WebSocket 消息推送能力，便于测试时 mock。
+type Sender interface {
+    SendSTTResult(result models.WsSTTResult) error
+    SendLLMChunk(chunk models.WsLLMChunk) error
+    SendLLMDone(done models.WsLLMDone) error
+    SendTTSAudio(audio models.WsTTSAudio) error
+    SendError(err models.WsError) error
 }
 ```

+**Pipeline 实现**（`internal/orchestrator/pipeline.go`）：
+1. Base64 解码音频/图片
+2. 调用 `stt.Recognize()` → 发送 `stt_result`
+3. 调用 `llm.ChatStream()` 获取流式输出，goroutine 消费 token → 发送 `llm_chunk` + 句子切分
+4. 另一 goroutine 从句子 channel 读取 → 调用 `tts.SynthesizeStream()` → 发送 `tts_audio`
+5. 流结束 → 发送 `llm_done`
+6. TTS 失败静默跳过，STT/LLM 失败发送对应 error 消息
+
 ### 并发控制

 - 每个 `ProcessQuery` 调用在独立 goroutine 中运行
@@ -584,9 +532,9 @@ session:{id}:history → List   （对话历史）
 ### 接口定义

 ```go
-// SessionManager 会话管理器。
-// WebSocket Handler 通过此接口操作会话，不直接接触 Redis。
-type SessionManager interface {
+// Manager 会话管理器接口。
+// WebSocket Handler 通过此接口操作会话，不直接接触存储层。
+type Manager interface {
    // Create 创建新会话，返回 session ID。
    Create(ctx context.Context, config models.SessionConfig) (string, error)

@@ -605,14 +553,20 @@ type SessionManager interface {
    // SetActiveRequest 标记当前正在处理的请求 ID（interrupt 用）。
    SetActiveRequest(ctx context.Context, sessionID string, requestID string) error

+    // GetActiveRequestID 获取当前活跃请求 ID。
+    GetActiveRequestID(ctx context.Context, sessionID string) (string, error)
+
    // ClearActiveRequest 清除活跃请求标记（请求完成或中断后）。
    ClearActiveRequest(ctx context.Context, sessionID string) error

    // Touch 刷新 TTL（心跳时调用）。
    Touch(ctx context.Context, sessionID string) error

-    // Destroy 显式销毁会话（REST API DELETE 或连接断开清理）。
+    // Destroy 显式销毁会话（REST API DELETE）。
    Destroy(ctx context.Context, sessionID string) error
+
+    // ActiveCount 返回当前活跃会话数（健康检查用）。
+    ActiveCount() int
 }
 ```

@@ -629,7 +583,8 @@ case "query":

    history, _ := sessionMgr.GetHistory(ctx, sessionID, 20)    // 获取对话上下文

-    go orchestrator.ProcessQuery(ctx, client, &msg, history)   // 异步编排
+    sender := &WSClient{client: client, requestID: msg.RequestID}
+    go orch.ProcessQuery(ctx, sessionID, msg, history, sender) // 异步编排

 // interrupt 分支
 case "interrupt":
@@ -648,26 +603,30 @@ case "interrupt":
 联调阶段无 Redis 时，用同一接口的内存实现：

 ```go
-type InMemorySessionManager struct {
-    mu       sync.RWMutex
-    sessions map[string]*sessionEntry
+type MemoryManager struct {
+    mu          sync.RWMutex
+    sessions    map[string]*sessionEntry
+    ttl         time.Duration
+    maxHistory  int
+    stopCleaner chan struct{}
 }

 type sessionEntry struct {
    session     models.Session
    history     []models.Message
    activeReqID string
+    lastActive  time.Time
 }
 ```

 注入时根据配置切换：

 ```go
-var sessionMgr SessionManager
+var sessionMgr session.Manager
 if cfg.Redis.Addr != "" {
-    sessionMgr = NewRedisSessionManager(redisClient, 30*time.Minute, 20)
+    sessionMgr = session.NewRedisManager(redisClient, 30*time.Minute, 20)
 } else {
-    sessionMgr = NewInMemorySessionManager()
+    sessionMgr = session.NewMemoryManager(30*time.Minute, 20)
 }
 ```

@@ -931,10 +890,8 @@ type QueryRequest struct {
 }

 type Message struct {
-    Role      string `json:"role"`       // "user" | "assistant"
-    Content   string `json:"content"`
-    ImageURL  string `json:"image_url,omitempty"`
-    TokensUsed int   `json:"tokens_used,omitempty"`
+    Role    string `json:"role"`    // "user" | "assistant"
+    Content string `json:"content"`
 }
 ```

@@ -1085,3 +1042,25 @@ function reconnect(attempt: number) {
 }
 // attempt: 0 → 1s, 1 → 2s, 2 → 4s, 3 → 8s, ... 最大 30s
 ```
+
+### 跨域处理
+
+采用 **Nginx 同源反代**方案，前后端统一到同一域名，浏览器层面不存在跨域问题。
+
+**生产环境**：Nginx 将 `/`（前端）、`/api/*`（REST）、`/ws`（WebSocket）统一反代到同一域名，详见 `02-系统架构.md` 部署架构章节。
+
+**开发环境**：Vite 内置代理，前端 :5173 的 `/api` 和 `/ws` 请求代理到后端 :8080：
+
+```typescript
+// frontend/vite.config.ts
+server: {
+  proxy: {
+    "/api": "http://localhost:8080",
+    "/ws":  { target: "ws://localhost:8080", ws: true },
+  },
+},
+```
+
+**Go 后端 WebSocket CheckOrigin**：生产环境 Nginx 同源，`CheckOrigin` 可保持默认（拒绝跨域）。开发环境由 Vite proxy 转发，不存在跨域。因此后端无需配置 CORS 中间件，`CheckOrigin` 保持 gorilla/websocket 默认值即可。
+
+> 如果未来需要支持第三方客户端直连（如移动端），再按需添加 CORS 中间件和 `CheckOrigin` 白名单。
--- a/docs/PLAN_BACKEND.md
+++ b/docs/PLAN_BACKEND.md
@@ -0,0 +1,221 @@
+# CamTalk 后端完善计划
+
+## Context
+
+后端当前是一个骨架：`main.go` 启动 Gin 服务器，`ws/handler.go` 实现了 WebSocket 连接生命周期和消息分发，`models/models.go` 定义了所有协议消息类型，`config/config.go` 实现了 Viper 配置加载。但所有业务逻辑都是 TODO 桩——没有 Session Manager、没有 AI 服务客户端、没有编排层、没有日志/错误工具、没有测试。前端已基本完成，正在等待后端提供真实的 AI 管道。
+
+**目标**：按设计文档（`docs/03-接口文档.md` 为最高依据）逐步填充所有业务模块，使端到端的 STT → LLM → TTS 流式管道可用。
+
+---
+
+## 分阶段实施
+
+### Phase 1：基础设施（logger、errors、config 接入、graceful shutdown）
+
+**目标**：为后续模块提供日志、错误码、配置等基础能力，替换 `main.go` 中的硬编码值。
+
+| # | 任务 | 文件 | 说明 |
+|---|------|------|------|
+| 1.1 | 实现 Zap 日志封装 | `internal/logger/logger.go` | 提供 `Init(level, format)` 和全局 `*zap.SugaredLogger`，替换所有 `log.Printf` |
+| 1.2 | 实现错误码常量 + WS 错误发送工具 | `internal/errors/codes.go` | 10 个错误码常量 + `SendWSError(client, code, requestID, err)` |
+| 1.3 | main.go 接入 config.Load() | `cmd/server/main.go` | 用 `cfg.Server.Host:Port` 替换硬编码 `:8080`，初始化 logger |
+| 1.4 | 添加 graceful shutdown | `cmd/server/main.go` | `signal.NotifyContext` + `http.Server.Shutdown`，10s drain |
+| 1.5 | 添加 .gitignore | `backend/.gitignore` | 排除 `server` 二进制、`.env`、`tmp/` |
+
+> **CORS**：不在此处实现，生产环境由 Nginx 反向代理统一处理跨域。
+
+---
+
+### Phase 2：Session Manager
+
+**目标**：实现会话生命周期管理，让 WS handler 能追踪会话、存储对话历史。
+
+| # | 任务 | 文件 | 说明 |
+|---|------|------|------|
+| 2.1 | 定义 SessionManager 接口 | `internal/session/manager.go` | 方法：`Create`, `Get`, `UpdateConfig`, `GetHistory`, `AppendMessage`, `SetActiveRequest`, `ClearActiveRequest`, `Touch`, `Destroy` |
+| 2.2 | 实现内存版 SessionManager | `internal/session/memory.go` | `sync.RWMutex` + `map[string]*sessionEntry`，TTL 30 分钟，历史上限 20 条 |
+| 2.3 | 实现 Redis 版 SessionManager | `internal/session/redis.go` | `session:{id}:meta` Hash + `session:{id}:history` List，TTL 刷新，选配 |
+| 2.4 | 编写 Session Manager 测试 | `internal/session/memory_test.go` | 覆盖 Create/Get/Expire/Destroy/AppendMessage/History 上限 |
+| 2.5 | WS handler 接入 SessionManager | `internal/ws/handler.go` | `ServeWS` 接收 `session.Manager` 参数；`connected` 消息后创建会话；`query` 时 Touch + SetActiveRequest；`config` 时 UpdateConfig；断开时不销毁（自然过期） |
+
+---
+
+### Phase 3：AI 服务层接口 + 实现
+
+**目标**：定义并实现三个 AI 服务客户端，每个服务一个独立包。
+
+| # | 任务 | 文件 | 说明 |
+|---|------|------|------|
+| **3a. STT** | | | |
+| 3.1 | STT 接口定义 | `internal/ai/stt/stt.go` | `Service` 接口：`Recognize(ctx, audio []byte, opts Options) (string, error)`。`Options`: Encoding, SampleRate, Language |
+| 3.2 | Deepgram 实现 | `internal/ai/stt/deepgram.go` | WebSocket 连接 `wss://api.deepgram.com/v1/listen`，发送 PCM 音频，接收转录结果，5s 超时 |
+| 3.3 | STT 测试（mock） | `internal/ai/stt/deepgram_test.go` | httptest/WebSocket mock，验证连接、发送、超时 |
+| **3b. LLM** | | | |
+| 3.4 | LLM 接口定义 | `internal/ai/llm/llm.go` | `Service` 接口：`ChatStream(ctx, req Request) (<-chan Chunk, error)`。`Request`: Image, Text, History, Language。`Chunk`: Delta, Done, TokensUsed, Model |
+| 3.5 | OpenAI 实现 | `internal/ai/llm/openai.go` | `POST /v1/chat/completions` + `stream: true`，SSE 解析，10s 超时，image 以 `data:image/jpeg;base64,...` 传入 |
+| 3.6 | System Prompt 定义 | `internal/ai/llm/prompt.go` | 中文视觉助手提示词，根据 Language/DetailLevel 动态构建 |
+| 3.7 | LLM 测试（mock） | `internal/ai/llm/openai_test.go` | httptest mock SSE 流，验证流式解析、超时、错误处理 |
+| **3c. TTS** | | | |
+| 3.8 | TTS 接口定义 | `internal/ai/tts/tts.go` | `Service` 接口：`SynthesizeStream(ctx, textStream <-chan string, opts Options) (<-chan Chunk, error)`。`Chunk`: Audio []byte, IsLast |
+| 3.9 | OpenAI 实现 | `internal/ai/tts/openai.go` | `POST /v1/audio/speech` 模型 `tts-1`，逐句发送，返回 MP3 流，5s/句超时 |
+| 3.10 | TTS 测试（mock） | `internal/ai/tts/openai_test.go` | httptest mock，验证逐句合成、超时 |
+
+---
+
+### Phase 4：AI Orchestrator（核心编排）
+
+**目标**：实现 STT → LLM → TTS 流式并行管道，这是后端最关键的业务逻辑。
+
+| # | 任务 | 文件 | 说明 |
+|---|------|------|------|
+| 4.1 | Orchestrator 接口 | `internal/orchestrator/orchestrator.go` | `ProcessQuery(ctx, sessionID, req, history, sender)` — 接收查询并执行管道 |
+| 4.2 | Sender 接口 | `internal/orchestrator/sender.go` | 抽象 WS 推送：`SendSTTResult`, `SendLLMChunk`, `SendLLMDone`, `SendTTSAudio`, `SendError`，便于测试 |
+| 4.3 | 管道实现 | `internal/orchestrator/pipeline.go` | ① `stt.Recognize()` → 发送 `stt_result` ② `llm.ChatStream()` 并行消费 token → 发送 `llm_chunk` + 句子切分 → channel ③ `tts.SynthesizeStream()` 从 channel 读取 → 发送 `tts_audio` ④ 流结束 → 发送 `llm_done` |
+| 4.4 | 句子切分器 | `internal/orchestrator/splitter.go` | 按 `。！？\n.!?` 切分，buffer size 4 channel |
+| 4.5 | 错误降级 | 同上文件 | STT 失败→STT_ERROR+abort；LLM 超时→LLM_TIMEOUT；TTS 失败→静默跳过 |
+| 4.6 | Interrupt 支持 | 同上文件 | context cancel 触发所有流中止 |
+| 4.7 | Orchestrator 测试 | `internal/orchestrator/pipeline_test.go` | mock 三个 AI service + mock sender，验证完整流程、中断、错误降级 |
+
+---
+
+### Phase 5：WS Handler 完整接入
+
+**目标**：将 Session Manager + Orchestrator 串入 WebSocket handler，实现端到端消息处理。
+
+| # | 任务 | 文件 | 说明 |
+|---|------|------|------|
+| 5.1 | Client 扩展 | `internal/ws/handler.go` | 添加 `session.Manager`、`orchestrator.Orchestrator`、`context.CancelFunc`（用于 interrupt） |
+| 5.2 | query 处理 | 同上 | 解码 audio Base64 → `stt.Recognize` 的输入；Touch 会话；设置 active request；启动 `orchestrator.ProcessQuery` goroutine |
+| 5.3 | config 处理 | 同上 | 调用 `session.UpdateConfig()` |
+| 5.4 | interrupt 处理 | 同上 | 查找 active request 的 cancel func，调用 `cancel()`，ClearActiveRequest |
+| 5.5 | Disconnect 处理 | 同上 | 取消当前活跃请求（如有），不销毁会话 |
+
+---
+
+### Phase 6：REST API 补全
+
+**目标**：补全设计文档中的 REST 端点。
+
+| # | 任务 | 文件 | 说明 |
+|---|------|------|------|
+| 6.1 | Session 路由 | `internal/api/session.go` | `POST /api/sessions` 创建会话，`DELETE /api/sessions/:id` 销毁会话 |
+| 6.2 | Health 更新 | `cmd/server/main.go` | 从 SessionManager 获取 `active_sessions` 真实值 |
+| 6.3 | 路由注册 | `cmd/server/main.go` | 统一注册 REST + WS 路由，注入依赖 |
+
+---
+
+### Phase 7：Rate Limiter + Model Router（可选/MVP 后）
+
+**目标**：防止滥用 + 智能模型选择，MVP 可简化或跳过。
+
+| # | 任务 | 文件 | 说明 |
+|---|------|------|------|
+| 7.1 | 令牌桶 Rate Limiter | `internal/middleware/ratelimit.go` | `golang.org/x/time/rate` 或自实现，按 session ID 限流 |
+| 7.2 | Rate Limiter 中间件 | `internal/middleware/ratelimit.go` | 在 WS query 路径上检查，超限返回 `RATE_LIMITED` |
+| 7.3 | Model Router | `internal/ai/router.go` | 规则引擎：简单识别→GPT-4o-mini，深度分析→GPT-4o，暂不实现 o1 |
+
+---
+
+### Phase 8：集成测试 + 文档同步
+
+| # | 任务 | 文件 | 说明 |
+|---|------|------|------|
+| 8.1 | WS 集成测试 | `internal/ws/handler_test.go` | 启动 Gin test server + gorilla websocket client，验证完整 query→stt_result→llm_chunk→llm_done→tts_audio 流程 |
+| 8.2 | 文档同步 | `docs/03-接口文档.md` | 代码实现与文档有偏差时更新文档 |
+| 8.3 | go.sum 清理 | `backend/` | `go mod tidy` 清理无用依赖 |
+
+---
+
+## 关键文件清单
+
+```
+backend/
+  cmd/server/main.go                    ← Phase 1.3, 1.4, 1.5, 6.2, 6.3
+  internal/
+    config/config.go                    ← 已完成，Phase 1.3 接入
+    logger/logger.go                    ← Phase 1.1（新建）
+    errors/codes.go                     ← Phase 1.2（新建）
+    models/models.go                    ← 已完成，可能小幅扩展
+    session/
+      manager.go                        ← Phase 2.1（新建）
+      memory.go                         ← Phase 2.2（新建）
+      redis.go                          ← Phase 2.3（新建）
+      memory_test.go                    ← Phase 2.4（新建）
+    ai/
+      stt/
+        stt.go                          ← Phase 3.1（新建）
+        deepgram.go                     ← Phase 3.2（新建）
+        deepgram_test.go                ← Phase 3.3（新建）
+      llm/
+        llm.go                          ← Phase 3.4（新建）
+        openai.go                       ← Phase 3.5（新建）
+        prompt.go                       ← Phase 3.6（新建）
+        openai_test.go                  ← Phase 3.7（新建）
+      tts/
+        tts.go                          ← Phase 3.8（新建）
+        openai.go                       ← Phase 3.9（新建）
+        openai_test.go                  ← Phase 3.10（新建）
+      router.go                         ← Phase 7.3（新建）
+    orchestrator/
+      orchestrator.go                   ← Phase 4.1（新建）
+      sender.go                         ← Phase 4.2（新建）
+      pipeline.go                       ← Phase 4.3, 4.4, 4.5, 4.6（新建）
+      pipeline_test.go                  ← Phase 4.7（新建）
+    api/
+      session.go                        ← Phase 6.1（新建）
+    middleware/
+      ratelimit.go                      ← Phase 7.1, 7.2（新建）
+    ws/
+      handler.go                        ← Phase 5.1-5.5（修改）
+      handler_test.go                   ← Phase 8.1（新建）
+```
+
+---
+
+## 新增依赖
+
+| 包 | 用途 | Phase |
+|----|------|-------|
+| `go.uber.org/zap` | 结构化日志 | 1 |
+| `github.com/redis/go-redis/v9` | Redis 客户端 | 2.3 |
+| `github.com/gorilla/websocket` | 已有，Deepgram WS 也复用 | 3.2 |
+
+---
+
+## 执行顺序与依赖关系
+
+```
+Phase 1 (基础设施)
+  ↓
+Phase 2 (Session Manager)
+  ↓
+Phase 3 (AI 服务层)  ← 可与 Phase 2 并行开发
+  ↓
+Phase 4 (Orchestrator)  ← 依赖 Phase 2 + 3
+  ↓
+Phase 5 (WS Handler 接入)  ← 依赖 Phase 4
+  ↓
+Phase 6 (REST API)  ← 依赖 Phase 2
+  ↓
+Phase 7 (Rate Limiter + Router)  ← 独立，可推后
+  ↓
+Phase 8 (集成测试 + 文档)
+```
+
+---
+
+## 验证方案
+
+1. **单元测试**：每个模块独立测试，mock 外部依赖（AI API、Redis）
+2. **集成测试**：`httptest` 启动 Gin server，用 gorilla/websocket 客户端模拟完整 query 流程
+3. **端到端手动测试**：启动后端 → 打开前端 → 摄像头+麦克风对话 → 验证 stt_result / llm_chunk / tts_audio 消息流
+4. **go vet + go test ./...** 通过
+
+---
+
+## 设计文档参考
+
+- 接口规范（最高优先级）：`docs/03-接口文档.md`
+- 系统架构：`docs/02-系统架构.md`
+- 技术选型：`docs/04-技术选型.md`
+- 成本控制：`docs/08-成本控制.md`
--- a/frontend/src/App.css
+++ b/frontend/src/App.css
@@ -1,19 +1,36 @@
 /* ============================================================
-   CamTalk — 主应用样式
+   CamTalk — Web 端应用样式
+   双栏布局：左侧视频面板 + 右侧聊天面板
   ============================================================ */

 :root {
  --color-primary: #2563eb;
  --color-primary-hover: #1d4ed8;
-  --color-bg: #0f172a;
-  --color-surface: #1e293b;
-  --color-text: #f1f5f9;
-  --color-text-muted: #94a3b8;
-  --color-border: #334155;
+  --color-bg: #0b0f1a;
+  --color-surface: #151b2b;
+  --color-surface-2: #1c2438;
+  --color-text: #e2e8f0;
+  --color-text-muted: #64748b;
+  --color-border: #1e293b;
  --color-success: #22c55e;
  --color-warning: #f59e0b;
  --color-error: #ef4444;
-  --radius: 8px;
+  --radius: 10px;
+  --radius-sm: 6px;
+}
+
+[data-theme="light"] {
+  --color-primary: #2563eb;
+  --color-primary-hover: #1d4ed8;
+  --color-bg: #f1f5f9;
+  --color-surface: #ffffff;
+  --color-surface-2: #f8fafc;
+  --color-text: #0f172a;
+  --color-text-muted: #64748b;
+  --color-border: #e2e8f0;
+  --color-success: #16a34a;
+  --color-warning: #d97706;
+  --color-error: #dc2626;
 }

 * {
@@ -22,205 +39,634 @@
  box-sizing: border-box;
 }

+html, body, #root {
+  height: 100%;
+}
+
 body {
-  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
+  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
  background: var(--color-bg);
  color: var(--color-text);
-  min-height: 100vh;
 }

+/* ---- App Shell ---- */
+
 .app {
  display: flex;
  flex-direction: column;
-  min-height: 100vh;
-  max-width: 900px;
-  margin: 0 auto;
-  padding: 0 16px;
+  height: 100vh;
+  overflow: hidden;
 }

 /* ---- Header ---- */

-.app-header {
+.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
-  padding: 16px 0;
-  border-bottom: 1px solid var(--color-border);
-}
-
-.app-header h1 {
-  font-size: 1.5rem;
-  font-weight: 700;
-}
-
-.status {
-  font-size: 0.85rem;
-  padding: 4px 12px;
-  border-radius: 12px;
+  padding: 0 20px;
+  height: 48px;
  background: var(--color-surface);
-}
-
-.status--connected {
-  color: var(--color-success);
-  border: 1px solid var(--color-success);
-}
-
-.status--connecting {
-  color: var(--color-warning);
-  border: 1px solid var(--color-warning);
-}
-
-.status--disconnected {
-  color: var(--color-text-muted);
-  border: 1px solid var(--color-border);
-}
-
-/* ---- Main ---- */
-
-.app-main {
-  flex: 1;
-  display: flex;
-  flex-direction: column;
-  gap: 16px;
-  padding: 16px 0;
-  overflow: hidden;
-}
-
-.video-section {
-  position: relative;
+  border-bottom: 1px solid var(--color-border);
  flex-shrink: 0;
 }

-.vad-indicator {
-  position: absolute;
-  bottom: 12px;
-  left: 12px;
-  background: rgba(0, 0, 0, 0.7);
-  color: var(--color-success);
-  padding: 6px 12px;
-  border-radius: var(--radius);
-  font-size: 0.85rem;
-  animation: pulse 1.5s ease-in-out infinite;
-}
-
-.vad-indicator--loading {
-  color: var(--color-warning);
-}
-
-.vad-indicator--error {
-  color: var(--color-error);
-  animation: none;
-}
-
-@keyframes pulse {
-  0%, 100% { opacity: 1; }
-  50% { opacity: 0.6; }
-}
-
-.chat-section {
-  flex: 1;
+.header__left {
  display: flex;
-  flex-direction: column;
+  align-items: baseline;
  gap: 12px;
-  overflow: hidden;
 }

-/* ---- Video Preview ---- */
-
-.video-preview {
-  position: relative;
-  width: 100%;
-  aspect-ratio: 4 / 3;
-  background: var(--color-surface);
-  border-radius: var(--radius);
-  overflow: hidden;
+.header__title {
+  font-size: 1.2rem;
+  font-weight: 700;
+  color: var(--color-text);
 }

-.video-preview__video {
-  width: 100%;
-  height: 100%;
-  object-fit: cover;
-}
-
-.video-preview__placeholder {
-  position: absolute;
-  inset: 0;
-  display: flex;
-  align-items: center;
-  justify-content: center;
+.header__subtitle {
+  font-size: 0.8rem;
  color: var(--color-text-muted);
 }

-/* ---- Chat Panel ---- */
+.header__right {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+}

-.chat-panel {
+.header__stats {
+  font-size: 0.75rem;
+  color: var(--color-text-muted);
+  padding: 4px 10px;
+  background: var(--color-surface-2);
+  border-radius: 12px;
+}
+
+.badge {
+  font-size: 0.75rem;
+  padding: 3px 10px;
+  border-radius: 12px;
+  font-weight: 500;
+}
+
+.badge--connected {
+  color: var(--color-success);
+  background: rgba(34, 197, 94, 0.1);
+  border: 1px solid rgba(34, 197, 94, 0.3);
+}
+
+.badge--connecting {
+  color: var(--color-warning);
+  background: rgba(245, 158, 11, 0.1);
+  border: 1px solid rgba(245, 158, 11, 0.3);
+}
+
+.badge--disconnected {
+  color: var(--color-text-muted);
+  background: var(--color-surface-2);
+  border: 1px solid var(--color-border);
+}
+
+.btn-icon {
+  background: none;
+  border: none;
+  font-size: 1.1rem;
+  cursor: pointer;
+  padding: 6px;
+  border-radius: var(--radius-sm);
+  transition: background 0.15s;
+  color: var(--color-text-muted);
+}
+
+.btn-icon:hover {
+  background: var(--color-surface-2);
+  color: var(--color-text);
+}
+
+.lang-group {
+  display: flex;
+  gap: 2px;
+  background: var(--color-surface-2);
+  border-radius: var(--radius-sm);
+  padding: 2px;
+}
+
+.lang-btn {
+  background: none;
+  border: none;
+  color: var(--color-text-muted);
+  font-size: 0.72rem;
+  font-weight: 600;
+  padding: 4px 10px;
+  border-radius: 4px;
+  cursor: pointer;
+  transition: all 0.15s;
+}
+
+.lang-btn:hover {
+  color: var(--color-text);
+}
+
+.lang-btn--active {
+  background: var(--color-primary);
+  color: white;
+}
+
+/* ---- Workspace (双栏) ---- */
+
+.workspace {
+  flex: 1;
+  display: flex;
+  overflow: hidden;
+}
+
+/* ---- 左侧视频面板 ---- */
+
+.video-panel {
+  width: 420px;
+  flex-shrink: 0;
  display: flex;
  flex-direction: column;
+  padding: 16px;
  gap: 12px;
-  overflow-y: auto;
+}
+
+.video-container {
+  position: relative;
+  aspect-ratio: 4 / 3;
+  background: var(--color-surface-2);
+  border-radius: var(--radius);
+  overflow: hidden;
+  border: 1px solid var(--color-border);
+}
+
+.video-container .video-preview {
+  width: 100%;
+  height: 100%;
+  border-radius: 0;
+}
+
+.video-container .video-preview__video {
+  width: 100%;
+  height: 100%;
+  object-fit: cover;
+  background: #1a1a2e;
+}
+
+.video-placeholder {
+  position: absolute;
+  inset: 0;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  gap: 8px;
+  color: var(--color-text-muted);
+  font-size: 0.82rem;
+}
+
+.video-placeholder__icon {
+  font-size: 2.4rem;
+  opacity: 0.2;
+  margin-bottom: 4px;
+}
+
+.video-indicator {
+  position: absolute;
+  bottom: 16px;
+  left: 16px;
+  background: rgba(0, 0, 0, 0.75);
+  backdrop-filter: blur(8px);
+  color: var(--color-success);
+  padding: 6px 14px;
+  border-radius: var(--radius-sm);
+  font-size: 0.8rem;
+  font-weight: 500;
+  animation: pulse 1.5s ease-in-out infinite;
+}
+
+.live-badge {
+  position: absolute;
+  top: 12px;
+  left: 12px;
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  background: rgba(0, 0, 0, 0.75);
+  backdrop-filter: blur(8px);
+  color: white;
+  padding: 4px 12px;
+  border-radius: var(--radius-sm);
+  font-size: 0.75rem;
+  font-weight: 600;
+  letter-spacing: 0.5px;
+}
+
+.live-badge__dot {
+  width: 8px;
+  height: 8px;
+  border-radius: 50%;
+  background: var(--color-success);
+  animation: pulse 1.5s ease-in-out infinite;
+}
+
+.video-indicator--loading { color: var(--color-warning); }
+.video-indicator--audio { left: auto; right: 16px; color: var(--color-primary); }
+.video-indicator--error { color: var(--color-error); animation: none; }
+
+.detail-badge {
+  position: absolute;
+  top: 12px;
+  right: 12px;
+  background: rgba(37, 99, 235, 0.85);
+  backdrop-filter: blur(8px);
+  color: white;
+  padding: 3px 10px;
+  border-radius: var(--radius-sm);
+  font-size: 0.7rem;
+  font-weight: 700;
+  letter-spacing: 0.5px;
+}
+
+.observation-badge {
+  position: absolute;
+  top: 12px;
+  left: 12px;
+  background: rgba(34, 197, 94, 0.85);
+  backdrop-filter: blur(8px);
+  color: white;
+  padding: 3px 10px;
+  border-radius: var(--radius-sm);
+  font-size: 0.7rem;
+  font-weight: 700;
+  animation: pulse 2s ease-in-out infinite;
+}
+
+.video-overlay {
+  position: absolute;
+  inset: 0;
+  background: rgba(0, 0, 0, 0.35);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  backdrop-filter: blur(2px);
+}
+
+.video-overlay__spinner {
+  width: 36px;
+  height: 36px;
+  border: 3px solid rgba(255, 255, 255, 0.2);
+  border-top-color: white;
+  border-radius: 50%;
+  animation: spin 0.8s linear infinite;
+}
+
+/* ---- 视频控制栏 ---- */
+
+.video-controls {
+  flex-shrink: 0;
+  display: flex;
+  justify-content: center;
+  padding: 4px 0;
+}
+
+.video-controls__row {
+  display: flex;
+  gap: 6px;
+  flex-wrap: wrap;
+  justify-content: center;
+}
+
+.btn--ctrl {
+  padding: 6px 12px;
+  font-size: 0.78rem;
+  border-radius: var(--radius-sm);
+  border: 1px solid var(--color-border);
+  background: var(--color-surface-2);
+  color: var(--color-text-muted);
+  cursor: pointer;
+  transition: all 0.15s;
+  white-space: nowrap;
+}
+
+.btn--ctrl:hover {
+  background: var(--color-border);
+  color: var(--color-text);
+}
+
+.btn--ctrl-on {
+  background: rgba(34, 197, 94, 0.15);
+  color: var(--color-success);
+  border-color: rgba(34, 197, 94, 0.3);
+}
+
+.btn--ctrl-off {
+  background: rgba(239, 68, 68, 0.1);
+  color: var(--color-error);
+  border-color: rgba(239, 68, 68, 0.2);
+}
+
+.btn--speaking {
+  animation: micPulse 0.8s ease-in-out infinite;
+  box-shadow: 0 0 12px rgba(34, 197, 94, 0.5);
+}
+
+@keyframes micPulse {
+  0%, 100% { box-shadow: 0 0 8px rgba(34, 197, 94, 0.4); transform: scale(1); }
+  50% { box-shadow: 0 0 16px rgba(34, 197, 94, 0.8); transform: scale(1.05); }
+}
+
+/* ---- 右侧聊天面板 ---- */
+
+.chat-panel-wrapper {
  flex: 1;
+  display: flex;
+  flex-direction: column;
+  background: var(--color-surface);
+  border-left: 1px solid var(--color-border);
+  min-width: 0;
+}
+
+.chat-panel-header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 12px 16px;
+  font-weight: 600;
+  font-size: 0.85rem;
+  border-bottom: 1px solid var(--color-border);
+  flex-shrink: 0;
+  color: var(--color-text-muted);
+}
+
+.chat-panel-header__mode {
+  font-size: 0.7rem;
+  font-weight: 500;
+  color: var(--color-success);
+  background: rgba(34, 197, 94, 0.1);
+  padding: 2px 8px;
+  border-radius: 10px;
+}
+
+.chat-panel-body {
+  flex: 1;
+  overflow: hidden;
+  display: flex;
+  flex-direction: column;
+}
+
+/* ---- Chat Panel (覆盖子组件样式) ---- */
+
+.chat-panel {
+  flex: 1;
+  overflow-y: auto;
+  padding: 12px 16px;
+  display: flex;
+  flex-direction: column;
+  gap: 10px;
 }

 .chat-panel--empty {
  display: flex;
  align-items: center;
  justify-content: center;
-  padding: 48px 0;
+  flex: 1;
  color: var(--color-text-muted);
+  font-size: 0.85rem;
 }

 .chat-message {
-  padding: 12px 16px;
-  border-radius: var(--radius);
-  background: var(--color-surface);
+  padding: 10px 14px;
+  border-radius: var(--radius-sm);
+  background: var(--color-surface-2);
+  max-width: 92%;
 }

 .chat-message--user {
-  border-left: 3px solid var(--color-primary);
+  border-left: 2px solid var(--color-primary);
+  align-self: flex-end;
+  background: rgba(37, 99, 235, 0.08);
 }

 .chat-message--assistant {
-  border-left: 3px solid var(--color-success);
+  border-left: 2px solid var(--color-success);
 }

 .chat-message--streaming {
-  opacity: 0.8;
+  opacity: 0.85;
 }

 .chat-message__role {
-  font-size: 0.75rem;
+  font-size: 0.65rem;
  font-weight: 600;
  text-transform: uppercase;
+  letter-spacing: 0.5px;
  color: var(--color-text-muted);
-  margin-bottom: 4px;
+  margin-bottom: 3px;
 }

 .chat-message__content {
-  font-size: 0.95rem;
-  line-height: 1.5;
+  font-size: 0.82rem;
+  line-height: 1.55;
  white-space: pre-wrap;
 }

-/* ---- Footer ---- */
-
-.app-footer {
-  display: flex;
-  gap: 12px;
-  justify-content: center;
-  padding: 16px 0;
-  border-top: 1px solid var(--color-border);
+.chat-message__meta {
+  margin-top: 6px;
+  font-size: 0.65rem;
+  color: var(--color-text-muted);
 }

+/* ---- Streaming Cursor ---- */
+
+.cursor {
+  display: inline;
+  animation: blink 0.8s step-end infinite;
+  color: var(--color-success);
+}
+
+/* ---- System Message ---- */
+
+.system-message {
+  text-align: center;
+  padding: 8px 16px;
+  margin: 0 20px;
+  border-radius: var(--radius-sm);
+  font-size: 0.8rem;
+}
+
+.system-message--warning {
+  background: rgba(245, 158, 11, 0.1);
+  color: var(--color-warning);
+  border: 1px solid rgba(245, 158, 11, 0.2);
+}
+
+/* ---- Drawer (Config Panel) ---- */
+
+.drawer-overlay {
+  position: fixed;
+  inset: 0;
+  z-index: 100;
+  background: rgba(0, 0, 0, 0.4);
+  backdrop-filter: blur(2px);
+  animation: fadeIn 0.2s ease;
+}
+
+.drawer {
+  position: absolute;
+  top: 0;
+  right: 0;
+  bottom: 0;
+  width: 320px;
+  background: var(--color-surface);
+  border-left: 1px solid var(--color-border);
+  display: flex;
+  flex-direction: column;
+  animation: slideInRight 0.25s ease;
+  box-shadow: -8px 0 24px rgba(0, 0, 0, 0.3);
+}
+
+.drawer__header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 14px 16px;
+  border-bottom: 1px solid var(--color-border);
+  flex-shrink: 0;
+}
+
+.drawer__title {
+  font-weight: 600;
+  font-size: 0.9rem;
+}
+
+.drawer__close {
+  background: none;
+  border: none;
+  color: var(--color-text-muted);
+  cursor: pointer;
+  font-size: 1rem;
+  padding: 4px 8px;
+  border-radius: var(--radius-sm);
+  transition: all 0.15s;
+}
+
+.drawer__close:hover {
+  background: var(--color-surface-2);
+  color: var(--color-text);
+}
+
+.drawer__body {
+  flex: 1;
+  overflow-y: auto;
+  padding: 16px;
+}
+
+/* ---- Config Group ---- */
+
+.config-group {
+  margin-bottom: 20px;
+}
+
+.config-group__title {
+  font-size: 0.7rem;
+  font-weight: 600;
+  text-transform: uppercase;
+  letter-spacing: 0.8px;
+  color: var(--color-text-muted);
+  margin-bottom: 12px;
+  padding-bottom: 8px;
+  border-bottom: 1px solid var(--color-border);
+}
+
+.config-row {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 10px 0;
+  font-size: 0.82rem;
+  color: var(--color-text);
+  cursor: pointer;
+}
+
+.config-row__info {
+  display: flex;
+  flex-direction: column;
+  gap: 2px;
+}
+
+.config-row__label {
+  font-weight: 500;
+  color: var(--color-text);
+}
+
+.config-row__desc {
+  font-size: 0.72rem;
+  color: var(--color-text-muted);
+}
+
+.config-row select,
+.config-row input[type="checkbox"] {
+  background: var(--color-surface-2);
+  color: var(--color-text);
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-sm);
+  padding: 5px 10px;
+  font-size: 0.8rem;
+  cursor: pointer;
+}
+
+.config-row input[type="checkbox"] {
+  width: 18px;
+  height: 18px;
+  cursor: pointer;
+}
+
+/* ---- Toast ---- */
+
+.toast-container {
+  position: fixed;
+  top: 68px;
+  right: 20px;
+  z-index: 1000;
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+}
+
+.toast {
+  padding: 10px 16px;
+  border-radius: var(--radius-sm);
+  font-size: 0.82rem;
+  cursor: pointer;
+  animation: slideIn 0.3s ease-out;
+  max-width: 320px;
+  backdrop-filter: blur(8px);
+}
+
+.toast--error { background: rgba(239, 68, 68, 0.9); color: white; }
+.toast--warning { background: rgba(245, 158, 11, 0.9); color: #000; }
+.toast--info { background: rgba(37, 99, 235, 0.9); color: white; }
+
 /* ---- Buttons ---- */

 .btn {
-  padding: 10px 24px;
+  padding: 8px 20px;
  border: none;
-  border-radius: var(--radius);
-  font-size: 0.95rem;
+  border-radius: var(--radius-sm);
+  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
-  transition: background 0.2s;
+  transition: all 0.15s;
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+}
+
+.btn--lg {
+  padding: 12px 32px;
+  font-size: 0.95rem;
+  border-radius: var(--radius);
 }

 .btn--primary {
@@ -233,7 +679,7 @@ body {
 }

 .btn--secondary {
-  background: var(--color-surface);
+  background: var(--color-surface-2);
  color: var(--color-text);
  border: 1px solid var(--color-border);
 }
@@ -247,16 +693,35 @@ body {
  color: #000;
 }

-.btn--warning:hover {
-  opacity: 0.9;
+.btn--warning:hover { opacity: 0.9; }
+
+.btn--danger {
+  background: rgba(239, 68, 68, 0.15);
+  color: var(--color-error);
+  border: 1px solid rgba(239, 68, 68, 0.3);
 }

-/* ---- Streaming Cursor ---- */
+.btn--danger:hover {
+  background: rgba(239, 68, 68, 0.25);
+}

-.cursor {
-  display: inline;
-  animation: blink 0.8s step-end infinite;
-  color: var(--color-success);
+.btn--active {
+  background: var(--color-primary);
+  color: white;
+  box-shadow: 0 0 12px rgba(37, 99, 235, 0.4);
+  animation: pulseBtn 2s ease-in-out infinite;
+}
+
+/* ---- Animations ---- */
+
+@keyframes pulse {
+  0%, 100% { opacity: 1; }
+  50% { opacity: 0.6; }
+}
+
+@keyframes pulseBtn {
+  0%, 100% { box-shadow: 0 0 12px rgba(37, 99, 235, 0.4); }
+  50% { box-shadow: 0 0 20px rgba(37, 99, 235, 0.7); }
 }

@keyframes blink {
@@ -264,97 +729,40 @@ body {
  50% { opacity: 0; }
 }

-/* ---- Message Meta ---- */
-
-.chat-message__meta {
-  margin-top: 6px;
-  font-size: 0.75rem;
-  color: var(--color-text-muted);
-}
-
-/* ---- System Message ---- */
-
-.system-message {
-  text-align: center;
-  padding: 8px 16px;
-  border-radius: var(--radius);
-  font-size: 0.85rem;
-}
-
-.system-message--warning {
-  background: rgba(245, 158, 11, 0.15);
-  color: var(--color-warning);
-  border: 1px solid rgba(245, 158, 11, 0.3);
-}
-
-/* ---- Toast ---- */
-
-.toast-container {
-  position: fixed;
-  top: 16px;
-  right: 16px;
-  z-index: 1000;
-  display: flex;
-  flex-direction: column;
-  gap: 8px;
-}
-
-.toast {
-  padding: 10px 16px;
-  border-radius: var(--radius);
-  font-size: 0.85rem;
-  cursor: pointer;
-  animation: slideIn 0.3s ease-out;
-  max-width: 320px;
-}
-
-.toast--error {
-  background: rgba(239, 68, 68, 0.9);
-  color: white;
-}
-
-.toast--warning {
-  background: rgba(245, 158, 11, 0.9);
-  color: #000;
-}
-
-.toast--info {
-  background: rgba(37, 99, 235, 0.9);
-  color: white;
-}
-
-@keyframes slideIn {
-  from {
-    opacity: 0;
-    transform: translateX(20px);
-  }
-  to {
-    opacity: 1;
-    transform: translateX(0);
-  }
-}
-
-/* ---- Video Overlay ---- */
-
-.video-overlay {
-  position: absolute;
-  inset: 0;
-  background: rgba(0, 0, 0, 0.3);
-  display: flex;
-  align-items: center;
-  justify-content: center;
-  border-radius: var(--radius);
-}
-
-.video-overlay__spinner {
-  width: 32px;
-  height: 32px;
-  border: 3px solid rgba(255, 255, 255, 0.3);
-  border-top-color: white;
-  border-radius: 50%;
-  animation: spin 0.8s linear infinite;
-}
-
@keyframes spin {
  to { transform: rotate(360deg); }
 }
+
+@keyframes slideIn {
+  from { opacity: 0; transform: translateX(20px); }
+  to { opacity: 1; transform: translateX(0); }
+}
+
+@keyframes fadeIn {
+  from { opacity: 0; }
+  to { opacity: 1; }
+}
+
+@keyframes slideInRight {
+  from { transform: translateX(100%); }
+  to { transform: translateX(0); }
+}
+
+/* ---- Scrollbar ---- */
+
+::-webkit-scrollbar {
+  width: 6px;
+}
+
+::-webkit-scrollbar-track {
+  background: transparent;
+}
+
+::-webkit-scrollbar-thumb {
+  background: var(--color-border);
+  border-radius: 3px;
+}
+
+::-webkit-scrollbar-thumb:hover {
+  background: var(--color-text-muted);
+}
--- a/frontend/src/App.tsx
+++ b/frontend/src/App.tsx
@@ -1,97 +1,235 @@
 // ============================================================
-// CamTalk — 主应用组件
+// CamTalk — 主应用组件（Web 端双栏布局）
 // ============================================================

+import { useCallback, useEffect, useRef, useState } from "react";
 import { useVisionSession } from "./hooks/useVisionSession";
 import { VideoPreview } from "./components/VideoPreview";
 import { ChatPanel } from "./components/ChatPanel";
+import { ConfigPanel } from "./components/ConfigPanel";
 import { ToastContainer } from "./components/Toast";
+import { loadTheme, saveTheme } from "./lib/storage";
+import type { Theme } from "./types";
 import "./App.css";

 function App() {
+  const [showConfig, setShowConfig] = useState(false);
+  const [theme, setTheme] = useState<Theme>(loadTheme);
+  const [elapsed, setElapsed] = useState(0);
+  const timerRef = useRef<ReturnType<typeof setInterval> | null>(null);
+
+  // 切换主题时更新 <html> 的 data-theme 属性
+  useEffect(() => {
+    document.documentElement.setAttribute("data-theme", theme);
+  }, [theme]);
+
+  const handleThemeChange = useCallback((t: Theme) => {
+    setTheme(t);
+    saveTheme(t);
+  }, []);
+
+  const formatTime = (s: number) => {
+    const m = Math.floor(s / 60);
+    const sec = s % 60;
+    return `${m.toString().padStart(2, "0")}:${sec.toString().padStart(2, "0")}`;
+  };
+
  const {
    messages,
    currentReply,
    isProcessing,
+    isAudioPlaying,
    isSpeaking,
    isVADReady,
    vadError,
    connectionStatus,
    videoRef,
    stream,
+    config,
+    updateConfig,
+    stats,
+    mode,
+    isObserving,
+    toggleMode,
    startSession,
    stopSession,
    interrupt,
+    isCameraOn,
+    isMicOn,
+    toggleCamera,
+    toggleMic,
  } = useVisionSession();

  const isConnected = connectionStatus === "connected";

+  // 连接计时器
+  const elapsedRef = useRef(0);
+  useEffect(() => {
+    if (isConnected) {
+      elapsedRef.current = 0;
+      setElapsed(0); // eslint-disable-line react-hooks/set-state-in-effect -- 连接时重置计时器
+    }
+  }, [isConnected]);
+
+  useEffect(() => {
+    if (!isConnected) {
+      if (timerRef.current) {
+        clearInterval(timerRef.current);
+        timerRef.current = null;
+      }
+      return;
+    }
+    const id = setInterval(() => {
+      elapsedRef.current += 1;
+      setElapsed(elapsedRef.current);
+    }, 1000);
+    timerRef.current = id;
+    return () => clearInterval(id);
+  }, [isConnected]);
+
  return (
    <div className="app">
-      <header className="app-header">
-        <h1>CamTalk</h1>
-        <span className={`status status--${connectionStatus}`}>
-          {isConnected
-            ? "已连接"
-            : connectionStatus === "connecting"
-              ? "连接中..."
-              : "未连接"}
-        </span>
+      {/* ---- 顶部导航栏 ---- */}
+      <header className="header">
+        <div className="header__left">
+          <h1 className="header__title">CamTalk</h1>
+          <span className="header__subtitle">AI 视觉对话助手</span>
+        </div>
+        <div className="header__right">
+          {isConnected && (stats.queryCount > 0 || stats.totalTokens > 0) && (
+            <span className="header__stats">
+              {stats.queryCount} 次请求 · {stats.totalTokens} tokens
+            </span>
+          )}
+          <span className={`badge badge--${connectionStatus}`}>
+            {isConnected ? "已连接" : connectionStatus === "connecting" ? "连接中..." : "未连接"}
+          </span>
+          <button
+            className="btn-icon"
+            onClick={() => setShowConfig((v) => !v)}
+            title="设置"
+          >
+            ⚙️
+          </button>
+        </div>
      </header>

-      <main className="app-main">
-        <div className="video-section">
-          <VideoPreview ref={videoRef} isStreaming={!!stream} />
-          {isSpeaking && <div className="vad-indicator">🎤 正在聆听...</div>}
-          {isConnected && !isVADReady && !vadError && (
-            <div className="vad-indicator vad-indicator--loading">
-              正在初始化语音检测...
-            </div>
-          )}
-          {vadError && (
-            <div className="vad-indicator vad-indicator--error">
-              ⚠️ {vadError}
-            </div>
-          )}
-          {isProcessing && (
-            <div className="video-overlay">
-              <div className="video-overlay__spinner" />
-            </div>
-          )}
-        </div>
+      {showConfig && (
+        <ConfigPanel
+          config={config}
+          theme={theme}
+          onUpdate={updateConfig}
+          onThemeChange={handleThemeChange}
+          onClose={() => setShowConfig(false)}
+        />
+      )}

-        <div className="chat-section">
-          {connectionStatus === "disconnected" && messages.length > 0 && (
-            <div className="system-message system-message--warning">
-              连接已断开，正在重连...
-            </div>
-          )}
-          <ChatPanel
-            messages={messages}
-            currentReply={currentReply}
-            connectionStatus={connectionStatus}
-          />
-        </div>
-      </main>
-
-      <footer className="app-footer">
-        {!isConnected ? (
-          <button className="btn btn--primary" onClick={startSession}>
-            {connectionStatus === "connecting" ? "连接中..." : "开始对话"}
-          </button>
-        ) : (
-          <>
-            <button className="btn btn--secondary" onClick={stopSession}>
-              结束对话
-            </button>
-            {isProcessing && (
-              <button className="btn btn--warning" onClick={interrupt}>
-                打断
-              </button>
+      {/* ---- 主体：左侧视频 + 右侧聊天 ---- */}
+      <div className="workspace">
+        {/* 左侧：视频预览 + 控制栏 */}
+        <div className="video-panel">
+          <div className="video-container">
+            <VideoPreview ref={videoRef} isStreaming={!!stream} />
+            {isConnected && (
+              <div className="live-badge">
+                <span className="live-badge__dot" />
+                LIVE {formatTime(elapsed)}
+              </div>
            )}
-          </>
-        )}
-      </footer>
+            {config.detailLevel === "high" && (
+              <div className="detail-badge">HD</div>
+            )}
+            {isObserving && (
+              <div className="observation-badge">👁️ 观察中</div>
+            )}
+            {isSpeaking && (
+              <div className="video-indicator">🎤 正在聆听...</div>
+            )}
+            {isAudioPlaying && config.ttsEnabled && (
+              <div className="video-indicator video-indicator--audio">🔊 正在播放...</div>
+            )}
+            {isConnected && !isVADReady && !vadError && (
+              <div className="video-indicator video-indicator--loading">正在初始化语音检测...</div>
+            )}
+            {vadError && (
+              <div className="video-indicator video-indicator--error">⚠️ {vadError}</div>
+            )}
+            {isProcessing && (
+              <div className="video-overlay">
+                <div className="video-overlay__spinner" />
+              </div>
+            )}
+            {!isConnected && !stream && (
+              <div className="video-placeholder">
+                <span className="video-placeholder__icon">📷</span>
+                <span>点击右侧按钮开始对话</span>
+              </div>
+            )}
+          </div>
+
+          {/* 视频下方控制栏 */}
+          <div className="video-controls">
+            {!isConnected ? (
+              <button className="btn btn--primary btn--lg" onClick={startSession}>
+                {connectionStatus === "connecting" ? "连接中..." : "🎙️ 开始对话"}
+              </button>
+            ) : (
+              <div className="video-controls__row">
+                <button
+                  className={`btn btn--ctrl ${isCameraOn ? "btn--ctrl-on" : "btn--ctrl-off"}`}
+                  onClick={toggleCamera}
+                  title={isCameraOn ? "关闭摄像头" : "开启摄像头"}
+                >
+                  📷
+                </button>
+                <button
+                  className={`btn btn--ctrl ${isMicOn ? "btn--ctrl-on" : "btn--ctrl-off"} ${isSpeaking ? "btn--speaking" : ""}`}
+                  onClick={toggleMic}
+                  title={isMicOn ? "关闭麦克风" : "开启麦克风"}
+                >
+                  🎤
+                </button>
+                <button
+                  className={`btn ${mode === "observation" ? "btn--active" : "btn--secondary"}`}
+                  onClick={toggleMode}
+                >
+                  {mode === "observation" ? "👁️ 观察中" : "👁️ 观察模式"}
+                </button>
+                {isProcessing && (
+                  <button className="btn btn--warning" onClick={interrupt}>
+                    ⏹ 打断
+                  </button>
+                )}
+                <button className="btn btn--danger" onClick={stopSession}>
+                  结束对话
+                </button>
+              </div>
+            )}
+          </div>
+        </div>
+
+        {/* 右侧：聊天面板 */}
+        <div className="chat-panel-wrapper">
+          <div className="chat-panel-header">
+            <span>对话</span>
+            {isConnected && mode === "observation" && (
+              <span className="chat-panel-header__mode">观察模式</span>
+            )}
+          </div>
+          <div className="chat-panel-body">
+            {connectionStatus === "disconnected" && messages.length > 0 && (
+              <div className="system-message system-message--warning">
+                连接已断开，正在重连...
+              </div>
+            )}
+            <ChatPanel
+              messages={messages}
+              currentReply={currentReply}
+              connectionStatus={connectionStatus}
+            />
+          </div>
+        </div>
+      </div>

      <ToastContainer />
    </div>
--- a/frontend/src/components/ConfigPanel/index.tsx
+++ b/frontend/src/components/ConfigPanel/index.tsx
@@ -0,0 +1,92 @@
+// ============================================================
+// ConfigPanel — 右侧抽屉式配置面板
+// 职责：主题切换、TTS 开关、detail level 切换、语言选择
+// ============================================================
+
+import type { SessionConfig, Theme } from "../../types";
+
+interface ConfigPanelProps {
+  config: SessionConfig;
+  theme: Theme;
+  onUpdate: (partial: Partial<SessionConfig>) => void;
+  onThemeChange: (theme: Theme) => void;
+  onClose: () => void;
+}
+
+export function ConfigPanel({ config, theme, onUpdate, onThemeChange, onClose }: ConfigPanelProps) {
+  return (
+    <div className="drawer-overlay" onClick={onClose}>
+      <div className="drawer" onClick={(e) => e.stopPropagation()}>
+        <div className="drawer__header">
+          <span className="drawer__title">设置</span>
+          <button className="drawer__close" onClick={onClose}>✕</button>
+        </div>
+
+        <div className="drawer__body">
+          <div className="config-group">
+            <div className="config-group__title">外观</div>
+
+            <label className="config-row">
+              <div className="config-row__info">
+                <span className="config-row__label">主题</span>
+                <span className="config-row__desc">切换明暗主题</span>
+              </div>
+              <select
+                value={theme}
+                onChange={(e) => onThemeChange(e.target.value as Theme)}
+              >
+                <option value="dark">深色</option>
+                <option value="light">浅色</option>
+              </select>
+            </label>
+          </div>
+
+          <div className="config-group">
+            <div className="config-group__title">会话</div>
+
+            <label className="config-row">
+              <div className="config-row__info">
+                <span className="config-row__label">语音回答</span>
+                <span className="config-row__desc">AI 回答时同步播放语音</span>
+              </div>
+              <input
+                type="checkbox"
+                checked={config.ttsEnabled}
+                onChange={(e) => onUpdate({ ttsEnabled: e.target.checked })}
+              />
+            </label>
+
+            <label className="config-row">
+              <div className="config-row__info">
+                <span className="config-row__label">图像精度</span>
+                <span className="config-row__desc">高精度适合识别文字，低精度省流量</span>
+              </div>
+              <select
+                value={config.detailLevel}
+                onChange={(e) => onUpdate({ detailLevel: e.target.value as "low" | "high" })}
+              >
+                <option value="low">低</option>
+                <option value="high">高</option>
+              </select>
+            </label>
+
+            <label className="config-row">
+              <div className="config-row__info">
+                <span className="config-row__label">语言</span>
+                <span className="config-row__desc">交互语言偏好</span>
+              </div>
+              <select
+                value={config.language}
+                onChange={(e) => onUpdate({ language: e.target.value })}
+              >
+                <option value="zh-CN">中文</option>
+                <option value="en-US">English</option>
+                <option value="ja-JP">日本語</option>
+              </select>
+            </label>
+          </div>
+        </div>
+      </div>
+    </div>
+  );
+}
--- a/frontend/src/components/EdgeProcessor/index.tsx
+++ b/frontend/src/components/EdgeProcessor/index.tsx
@@ -103,19 +103,61 @@ export function useVAD(options?: VADOptions) {
  return { isSpeaking, isReady, error, start, stop };
 }

-// ---- 关键帧检测（ONNX Runtime Web）----
+// ---- 关键帧检测 ----

-export function useKeyframeDetection() {
-  // TODO: 加载 ONNX 模型后设为 true
-  const isReady = false;
+const DETECT_WIDTH = 160;
+const DETECT_HEIGHT = 120;
+const DIFF_THRESHOLD = 30;

-  const isKeyframe = useCallback(
-    (_currentFrame: ImageData, _previousFrame: ImageData): boolean => {
-      // TODO: 实现像素差异对比
-      return true; // 暂时所有帧都视为关键帧
-    },
-    [],
-  );
+/** 离屏 canvas，用于降采样 */
+let offscreen: HTMLCanvasElement | null = null;

-  return { isReady, isKeyframe };
+function getOffscreen(): HTMLCanvasElement {
+  if (!offscreen) {
+    offscreen = document.createElement("canvas");
+    offscreen.width = DETECT_WIDTH;
+    offscreen.height = DETECT_HEIGHT;
+  }
+  return offscreen;
+}
+
+/**
+ * 将 video 元素缩放采样为 Uint8ClampedArray（RGBA）
+ * 返回 null 如果 video 未就绪
+ */
+export function sampleFrame(video: HTMLVideoElement): Uint8ClampedArray | null {
+  if (video.readyState < 2) return null;
+  const canvas = getOffscreen();
+  const ctx = canvas.getContext("2d");
+  if (!ctx) return null;
+  ctx.drawImage(video, 0, 0, DETECT_WIDTH, DETECT_HEIGHT);
+  return ctx.getImageData(0, 0, DETECT_WIDTH, DETECT_HEIGHT).data;
+}
+
+/**
+ * 对比两帧像素差异
+ * @returns { isKeyframe: boolean, similarity: number }
+ */
+export function compareFrames(
+  prev: Uint8ClampedArray,
+  curr: Uint8ClampedArray,
+): { isKeyframe: boolean; similarity: number } {
+  let diffSum = 0;
+  const len = Math.min(prev.length, curr.length);
+  const pixelCount = len / 4;
+
+  for (let i = 0; i < len; i += 4) {
+    // 只比较 RGB，跳过 Alpha
+    diffSum += Math.abs(prev[i] - curr[i]);
+    diffSum += Math.abs(prev[i + 1] - curr[i + 1]);
+    diffSum += Math.abs(prev[i + 2] - curr[i + 2]);
+  }
+
+  const avgDiff = diffSum / (pixelCount * 3);
+  const similarity = 1 - avgDiff / 255;
+
+  return {
+    isKeyframe: avgDiff > DIFF_THRESHOLD,
+    similarity,
+  };
 }
--- a/frontend/src/hooks/useObservationMode.ts
+++ b/frontend/src/hooks/useObservationMode.ts
@@ -0,0 +1,88 @@
+// ============================================================
+// useObservationMode — 观察模式 Hook
+// 职责：定时采帧 → 关键帧检测 → 画面变化时触发回调
+// 来源：docs/05-用户故事.md US-05（持续场景监控）
+// ============================================================
+
+import { useCallback, useEffect, useRef, useState } from "react";
+import { sampleFrame, compareFrames } from "../components/EdgeProcessor";
+
+/** 画面变化显著阈值 */
+const CHANGE_THRESHOLD = 0.85;
+/** 采样间隔（ms） */
+const SAMPLE_INTERVAL = 5000;
+
+export interface ObservationOptions {
+  /** 画面变化回调，携带当前帧的 DataURL */
+  onChange?: (frameDataUrl: string) => void;
+}
+
+export function useObservationMode(options?: ObservationOptions) {
+  const [isObserving, setIsObserving] = useState(false);
+  const intervalRef = useRef<ReturnType<typeof setInterval> | null>(null);
+  const prevFrameRef = useRef<Uint8ClampedArray | null>(null);
+  const optionsRef = useRef(options);
+
+  useEffect(() => {
+    optionsRef.current = options;
+  }, [options]);
+
+  /**
+   * 启动观察模式
+   * @param video 摄像头 video 元素
+   * @param captureFrame 从 video 捕获 DataURL 的函数
+   */
+  const startObserving = useCallback(
+    (video: HTMLVideoElement | null, captureFrame: () => string | null) => {
+      if (!video) return;
+
+      // 立即采一帧作为基准
+      prevFrameRef.current = sampleFrame(video);
+
+      intervalRef.current = setInterval(() => {
+        const current = sampleFrame(video);
+        if (!current) return;
+
+        if (prevFrameRef.current) {
+          const { similarity } = compareFrames(prevFrameRef.current, current);
+
+          if (similarity < CHANGE_THRESHOLD) {
+            console.log(
+              `[Observation] 画面变化 (similarity=${similarity.toFixed(2)})`,
+            );
+            const frameDataUrl = captureFrame();
+            if (frameDataUrl) {
+              optionsRef.current?.onChange?.(frameDataUrl);
+            }
+          }
+        }
+
+        prevFrameRef.current = current;
+      }, SAMPLE_INTERVAL);
+
+      setIsObserving(true);
+    },
+    [],
+  );
+
+  /** 停止观察模式 */
+  const stopObserving = useCallback(() => {
+    if (intervalRef.current) {
+      clearInterval(intervalRef.current);
+      intervalRef.current = null;
+    }
+    prevFrameRef.current = null;
+    setIsObserving(false);
+  }, []);
+
+  // 组件卸载时清理
+  useEffect(() => {
+    return () => {
+      if (intervalRef.current) {
+        clearInterval(intervalRef.current);
+      }
+    };
+  }, []);
+
+  return { isObserving, startObserving, stopObserving };
+}
--- a/frontend/src/hooks/useVisionSession.ts
+++ b/frontend/src/hooks/useVisionSession.ts
@@ -9,17 +9,52 @@ import { v4 as uuidv4 } from "uuid";
 import { wsClient } from "../lib/websocket";
 import { encodeAudioToBase64, dataUrlToBase64 } from "../lib/audio";
 import { getErrorMessage } from "../lib/errors";
+import { TTSPlayer } from "../lib/ttsPlayer";
 import { showToast } from "../lib/toast";
+import { loadConfig, saveConfig } from "../lib/storage";
 import { useCamera } from "../components/CameraManager";
 import { useMicrophone } from "../components/MicManager";
-import { useVAD } from "../components/EdgeProcessor";
+import { useVAD, sampleFrame, compareFrames } from "../components/EdgeProcessor";
 import { useWebSocketManager } from "../components/WebSocketManager";
-import type { ChatMessage, ServerMessage, LLMDoneMessage } from "../types";
+import { useObservationMode } from "./useObservationMode";
+import type { ChatMessage, SessionConfig, ServerMessage, LLMDoneMessage } from "../types";
+
+export type SessionMode = "dialogue" | "observation";
+
+const MAX_HISTORY_ROUNDS = 10;
+
+export interface SessionStats {
+  queryCount: number;
+  totalTokens: number;
+}

 export function useVisionSession() {
  const [messages, setMessages] = useState<ChatMessage[]>([]);
  const [currentReply, setCurrentReply] = useState<string>("");
  const [isProcessing, setIsProcessing] = useState(false);
+  const [isAudioPlaying, setIsAudioPlaying] = useState(false);
+  const [config, setConfig] = useState<SessionConfig>(loadConfig);
+  const [stats, setStats] = useState<SessionStats>({ queryCount: 0, totalTokens: 0 });
+  const [mode, setMode] = useState<SessionMode>("dialogue");
+  const [isCameraOn, setIsCameraOn] = useState(false);
+  const [isMicOn, setIsMicOn] = useState(false);
+
+  // 上一帧采样数据（用于关键帧检测）
+  const prevFrameRef = useRef<Uint8ClampedArray | null>(null);
+
+  // 对话历史（role + content），用于多轮上下文
+  const historyRef = useRef<Array<{ role: string; content: string }>>([]);
+
+  // TTS 播放器
+  const ttsPlayerRef = useRef<TTSPlayer | null>(null);
+  const getTTSPlayer = useCallback(() => {
+    if (!ttsPlayerRef.current) {
+      const player = new TTSPlayer();
+      player.onEnd(() => setIsAudioPlaying(false));
+      ttsPlayerRef.current = player;
+    }
+    return ttsPlayerRef.current;
+  }, []);

  const { videoRef, captureFrame, startCamera, stopCamera, stream } = useCamera();
  const { startMic, stopMic } = useMicrophone();
@@ -31,6 +66,82 @@ export function useVisionSession() {
    isProcessingRef.current = isProcessing;
  }, [isProcessing]);

+  // 观察模式：画面变化时自动发送 query
+  const { isObserving, startObserving, stopObserving } = useObservationMode({
+    onChange: useCallback(
+      (frameDataUrl: string) => {
+        if (isProcessingRef.current) return;
+
+        const requestId = uuidv4();
+        send({
+          type: "query",
+          request_id: requestId,
+          image: dataUrlToBase64(frameDataUrl),
+          audio: "", // 观察模式无音频
+        });
+
+        setMessages((prev) => [
+          ...prev,
+          {
+            role: "user",
+            content: "👁️ 画面变化检测",
+            timestamp: Date.now(),
+          },
+        ]);
+        setStats((prev) => ({ ...prev, queryCount: prev.queryCount + 1 }));
+        setIsProcessing(true);
+      },
+      [send],
+    ),
+  });
+
+  /** 切换对话/观察模式 */
+  const toggleMode = useCallback(() => {
+    setMode((prev) => {
+      const next = prev === "dialogue" ? "observation" : "dialogue";
+      if (next === "observation") {
+        startObserving(videoRef.current, captureFrame);
+      } else {
+        stopObserving();
+      }
+      return next;
+    });
+  }, [videoRef, captureFrame, startObserving, stopObserving]);
+
+  // WebSocket 连接成功后发送 config
+  useEffect(() => {
+    if (status === "connected") {
+      send({
+        type: "config",
+        payload: {
+          tts_enabled: config.ttsEnabled,
+          detail_level: config.detailLevel,
+          language: config.language,
+        },
+      });
+    }
+  }, [status]); // eslint-disable-line react-hooks/exhaustive-deps -- 仅在连接状态变化时发送
+
+  /** 更新会话配置 */
+  const updateConfig = useCallback((partial: Partial<SessionConfig>) => {
+    setConfig((prev) => {
+      const next = { ...prev, ...partial };
+      saveConfig(next);
+      // 如果已连接，立即发送更新
+      if (status === "connected") {
+        send({
+          type: "config",
+          payload: {
+            tts_enabled: next.ttsEnabled,
+            detail_level: next.detailLevel,
+            language: next.language,
+          },
+        });
+      }
+      return next;
+    });
+  }, [status, send]);
+
  // VAD：语音结束时自动发送 query
  const {
    isSpeaking,
@@ -53,6 +164,23 @@ export function useVisionSession() {
          return;
        }

+        // 关键帧检测：与上一帧对比，相似度过高则跳过
+        const video = videoRef.current;
+        if (video) {
+          const currentSample = sampleFrame(video);
+          if (currentSample && prevFrameRef.current) {
+            const { similarity } = compareFrames(prevFrameRef.current, currentSample);
+            if (similarity > 0.9) {
+              console.log(`[Session] 画面无变化 (similarity=${similarity.toFixed(2)})，跳过`);
+              prevFrameRef.current = currentSample;
+              return;
+            }
+          }
+          if (currentSample) {
+            prevFrameRef.current = currentSample;
+          }
+        }
+
        const requestId = uuidv4();
        send({
          type: "query",
@@ -61,6 +189,9 @@ export function useVisionSession() {
          audio: encodeAudioToBase64(audio),
        });

+        // 更新请求统计
+        setStats((prev) => ({ ...prev, queryCount: prev.queryCount + 1 }));
+
        // 添加用户消息（STT 流式结果会逐步更新文本）
        setMessages((prev) => [
          ...prev,
@@ -68,7 +199,7 @@ export function useVisionSession() {
        ]);
        setIsProcessing(true);
      },
-      [captureFrame, send]
+      [captureFrame, send, videoRef]
    ),
  });

@@ -98,6 +229,21 @@ export function useVisionSession() {

        case "llm_done": {
          const done = msg as LLMDoneMessage;
+          // 记录到对话历史
+          historyRef.current.push({ role: "assistant", content: done.full_text });
+          // 裁剪历史到最近 N 轮
+          if (historyRef.current.length > MAX_HISTORY_ROUNDS * 2) {
+            historyRef.current = historyRef.current.slice(-MAX_HISTORY_ROUNDS * 2);
+          }
+
+          // 累计 token 统计
+          if (done.tokens_used?.total) {
+            setStats((prev) => ({
+              ...prev,
+              totalTokens: prev.totalTokens + done.tokens_used.total,
+            }));
+          }
+
          setMessages((prev) => [
            ...prev,
            {
@@ -115,7 +261,10 @@ export function useVisionSession() {
        }

        case "tts_audio":
-          // TODO: 阶段 5 音频流播放
+          getTTSPlayer().enqueue(msg.audio, msg.mime_type, msg.is_last);
+          if (!msg.is_last) {
+            setIsAudioPlaying(true);
+          }
          break;

        case "error":
@@ -127,25 +276,19 @@ export function useVisionSession() {
    });

    return unsub;
-  }, []);
-
-  // 连接断开时显示提示
-  useEffect(() => {
-    if (status === "disconnected") {
-      // 只在非主动断开时提示（通过检查是否有活跃会话判断）
-      // 这里简单处理，由 App 层根据状态显示
-    }
-  }, [status]);
+  }, [getTTSPlayer]);

  /** 启动会话 */
  const startSession = useCallback(async () => {
    // 1. 获取摄像头和麦克风
    await startCamera();
+    setIsCameraOn(true);
    const micStream = await startMic();
    if (!micStream) {
      showToast("无法获取麦克风权限", "error");
      return;
    }
+    setIsMicOn(true);

    // 2. 连接 WebSocket
    connect();
@@ -156,24 +299,60 @@ export function useVisionSession() {

  /** 结束会话 */
  const stopSession = useCallback(async () => {
+    stopObserving();
+    setMode("dialogue");
    await stopVAD();
    stopMic();
    stopCamera();
    disconnect();
-    // 清理所有对话状态
+    // 停止 TTS 并清理状态
+    ttsPlayerRef.current?.stop();
+    setIsAudioPlaying(false);
    setMessages([]);
    setCurrentReply("");
    setIsProcessing(false);
-  }, [stopVAD, stopMic, stopCamera, disconnect]);
+    setStats({ queryCount: 0, totalTokens: 0 });
+    historyRef.current = [];
+    prevFrameRef.current = null;
+    setIsCameraOn(false);
+    setIsMicOn(false);
+  }, [stopObserving, stopVAD, stopMic, stopCamera, disconnect]);
+
+  /** 摄像头开关 */
+  const toggleCamera = useCallback(async () => {
+    if (isCameraOn) {
+      stopCamera();
+      setIsCameraOn(false);
+    } else {
+      await startCamera();
+      setIsCameraOn(true);
+    }
+  }, [isCameraOn, startCamera, stopCamera]);
+
+  /** 麦克风开关 */
+  const toggleMic = useCallback(async () => {
+    if (isMicOn) {
+      stopMic();
+      setIsMicOn(false);
+    } else {
+      const micStream = await startMic();
+      setIsMicOn(!!micStream);
+    }
+  }, [isMicOn, startMic, stopMic]);

  /** 打断当前回复 */
  const interrupt = useCallback(() => {
    send({ type: "interrupt" });
+    // 停止 TTS 播放
+    ttsPlayerRef.current?.stop();
+    setIsAudioPlaying(false);
    // 将未完成的流式内容保存为最终消息
    if (currentReply) {
+      const interrupted = currentReply + "（已打断）";
+      historyRef.current.push({ role: "assistant", content: interrupted });
      setMessages((prev) => [
        ...prev,
-        { role: "assistant", content: currentReply + "（已打断）", timestamp: Date.now() },
+        { role: "assistant", content: interrupted, timestamp: Date.now() },
      ]);
    }
    setCurrentReply("");
@@ -184,14 +363,25 @@ export function useVisionSession() {
    messages,
    currentReply,
    isProcessing,
+    isAudioPlaying,
    isSpeaking,
    isVADReady,
    vadError,
    connectionStatus: status,
    videoRef,
    stream,
+    config,
+    updateConfig,
+    stats,
+    mode,
+    isObserving,
+    toggleMode,
    startSession,
    stopSession,
    interrupt,
+    isCameraOn,
+    isMicOn,
+    toggleCamera,
+    toggleMic,
  };
 }
--- a/frontend/src/index.css
+++ b/frontend/src/index.css
@@ -1,7 +1 @@
 /* 全局重置 — 详细样式在 App.css 中定义 */
-
-#root {
-  min-height: 100vh;
-  display: flex;
-  flex-direction: column;
-}
--- a/frontend/src/lib/sampling.ts
+++ b/frontend/src/lib/sampling.ts
@@ -0,0 +1,43 @@
+// ============================================================
+// Sampling — 混合采样策略
+// 来源：docs/08-成本控制.md — "定时低频 + 事件高频"
+// ============================================================
+
+/** 静默时采样间隔（ms） */
+const IDLE_INTERVAL = 5000;
+/** 用户说话时采样间隔（ms） */
+const ACTIVE_INTERVAL = 1000;
+
+export class SamplingController {
+  private lastSampleTime = 0;
+  private _isUserSpeaking = false;
+
+  /** 设置用户是否正在说话 */
+  set speaking(value: boolean) {
+    this._isUserSpeaking = value;
+  }
+
+  get speaking(): boolean {
+    return this._isUserSpeaking;
+  }
+
+  /** 当前采样间隔 */
+  get interval(): number {
+    return this._isUserSpeaking ? ACTIVE_INTERVAL : IDLE_INTERVAL;
+  }
+
+  /** 是否应该采样（基于时间间隔） */
+  shouldSample(): boolean {
+    const now = Date.now();
+    if (now - this.lastSampleTime < this.interval) {
+      return false;
+    }
+    this.lastSampleTime = now;
+    return true;
+  }
+
+  /** 强制允许下次采样（如用户刚说完话时） */
+  resetTimer(): void {
+    this.lastSampleTime = 0;
+  }
+}
--- a/frontend/src/lib/storage.ts
+++ b/frontend/src/lib/storage.ts
@@ -0,0 +1,52 @@
+// ============================================================
+// Storage — localStorage 封装
+// 职责：会话配置持久化
+// ============================================================
+
+import type { SessionConfig, Theme } from "../types";
+
+const CONFIG_KEY = "camtalk:config";
+const THEME_KEY = "camtalk:theme";
+
+const DEFAULT_CONFIG: SessionConfig = {
+  ttsEnabled: true,
+  detailLevel: "low",
+  language: "zh-CN",
+};
+
+/** 加载配置，无存储时返回默认值 */
+export function loadConfig(): SessionConfig {
+  try {
+    const raw = localStorage.getItem(CONFIG_KEY);
+    if (!raw) return DEFAULT_CONFIG;
+    const parsed = JSON.parse(raw) as Partial<SessionConfig>;
+    return { ...DEFAULT_CONFIG, ...parsed };
+  } catch {
+    return DEFAULT_CONFIG;
+  }
+}
+
+/** 保存配置到 localStorage */
+export function saveConfig(config: SessionConfig): void {
+  try {
+    localStorage.setItem(CONFIG_KEY, JSON.stringify(config));
+  } catch {
+    // localStorage 不可用时静默失败
+  }
+}
+
+/** 加载主题偏好 */
+export function loadTheme(): Theme {
+  try {
+    const raw = localStorage.getItem(THEME_KEY);
+    if (raw === "light" || raw === "dark") return raw;
+  } catch { /* ignore */ }
+  return "dark";
+}
+
+/** 保存主题偏好 */
+export function saveTheme(theme: Theme): void {
+  try {
+    localStorage.setItem(THEME_KEY, theme);
+  } catch { /* ignore */ }
+}
--- a/frontend/src/lib/ttsPlayer.ts
+++ b/frontend/src/lib/ttsPlayer.ts
@@ -0,0 +1,104 @@
+// ============================================================
+// TTS Player — 语音播放器
+// 职责：收集后端流式 tts_audio 片段，拼接后播放
+// 格式：MVP 仅支持 audio/mp3，pcm 为 TODO
+// ============================================================
+
+type OnEndCallback = () => void;
+
+export class TTSPlayer {
+  private chunks: string[] = [];
+  private audio: HTMLAudioElement | null = null;
+  private _isPlaying = false;
+  private onEndCallback: OnEndCallback | null = null;
+
+  /** 注册播放完成回调 */
+  onEnd(cb: OnEndCallback): void {
+    this.onEndCallback = cb;
+  }
+
+  /** 当前是否正在播放 */
+  get isPlaying(): boolean {
+    return this._isPlaying;
+  }
+
+  /**
+   * 入队一个 TTS 音频片段
+   * @param base64 Base64 编码的音频数据
+   * @param mimeType 音频格式（"audio/mp3" 或 "audio/pcm"）
+   * @param isLast 是否为最后一个片段
+   */
+  enqueue(base64: string, mimeType: string, isLast: boolean): void {
+    this.chunks.push(base64);
+
+    if (isLast) {
+      this.play(mimeType);
+    }
+  }
+
+  /** 停止播放并清空缓冲区 */
+  stop(): void {
+    if (this.audio) {
+      this.audio.pause();
+      this.audio.removeAttribute("src");
+      this.audio = null;
+    }
+    this.chunks = [];
+    this._isPlaying = false;
+  }
+
+  /** 暂停播放 */
+  pause(): void {
+    this.audio?.pause();
+  }
+
+  /** 恢复播放 */
+  resume(): void {
+    this.audio?.play();
+  }
+
+  /** 拼接所有片段并播放 */
+  private play(mimeType: string): void {
+    if (this.chunks.length === 0) return;
+
+    // 拼接所有 Base64 片段
+    const combined = this.chunks.join("");
+    this.chunks = [];
+
+    // Base64 → Uint8Array → Blob
+    const binary = atob(combined);
+    const bytes = new Uint8Array(binary.length);
+    for (let i = 0; i < binary.length; i++) {
+      bytes[i] = binary.charCodeAt(i);
+    }
+    const blob = new Blob([bytes], { type: mimeType });
+    const url = URL.createObjectURL(blob);
+
+    // 播放
+    const audio = new Audio(url);
+    this.audio = audio;
+    this._isPlaying = true;
+
+    audio.onended = () => {
+      URL.revokeObjectURL(url);
+      this._isPlaying = false;
+      this.audio = null;
+      this.onEndCallback?.();
+    };
+
+    audio.onerror = () => {
+      console.error("[TTS] 播放失败");
+      URL.revokeObjectURL(url);
+      this._isPlaying = false;
+      this.audio = null;
+      this.onEndCallback?.();
+    };
+
+    audio.play().catch((err) => {
+      console.error("[TTS] play() 被拒绝:", err);
+      this._isPlaying = false;
+      this.audio = null;
+      this.onEndCallback?.();
+    });
+  }
+}
--- a/frontend/src/types/index.ts
+++ b/frontend/src/types/index.ts
@@ -11,6 +11,8 @@ export interface SessionConfig {
  language: string;
 }

+export type Theme = "dark" | "light";
+
 export interface Session {
  sessionId: string;
  createdAt: string;