feat(gateway): persist chat sessions and messages in PostgreSQL

- store: new chat_sessions/chat_messages tables with CRUD, ILIKE message
  search, and auto-titling from the first user message
- context: optional Persister on the sliding-window store — messages are
  saved asynchronously on Add, sessions not in memory are restored from
  the database on Get
- orchestrator: ProcessInput/FinishRound now carry userID so persisted
  messages have an owner
- api: real session handlers (list/create/delete), message history and
  clear endpoints, working message search and three-format export
  (markdown/txt/json), fixing the short-ID panic in export
- main: migration, store wiring, ctxStore persister adapter

Tests: chat store handler lifecycle (fake store), context persister
save/restore, stub auth login flow updated.

backend/cmd/cyrene/main.go

@@ -37,10 +37,12 @@ import (
 	tracepkg "git.yeij.top/AskaEth/Cyrene_v2/services/ai-core/trace"
 	perfpkg "git.yeij.top/AskaEth/Cyrene_v2/services/ai-core/perf"
 	aiCoreCtx "git.yeij.top/AskaEth/Cyrene_v2/services/ai-core/context"
+	"git.yeij.top/AskaEth/Cyrene_v2/services/ai-core/model"
 	"git.yeij.top/AskaEth/Cyrene_v2/services/ai-core/orchestrator"
 	"git.yeij.top/AskaEth/Cyrene_v2/services/ai-core/persona"
 	"git.yeij.top/AskaEth/Cyrene_v2/services/ai-core/subsession"
 	"git.yeij.top/AskaEth/Cyrene_v2/services/gateway/api"
+	"git.yeij.top/AskaEth/Cyrene_v2/services/gateway/store"
 	"git.yeij.top/AskaEth/Cyrene_v2/services/gateway/ws"
 	"git.yeij.top/AskaEth/Cyrene_v2/services/memory"
 	bridge "git.yeij.top/AskaEth/Cyrene_v2/services/platform-bridge"
@@ -79,6 +81,7 @@ func main() {
 	} else {
 		defer database.Close()
 		db.RunMigration(context.Background(), database, "memories", db.SplitSQL(memory.CreateTableSQL()))
+		db.RunMigration(context.Background(), database, "chat", db.SplitSQL(store.CreateTableSQL()))
 	}
 
 	// === 3. NATS (in-process) ===
@@ -161,6 +164,14 @@ func main() {
 	ctxStore := aiCoreCtx.NewStore(4000, 50)
 	logger.Infof("[context] sliding window ready (4000 tokens, 50 turns)")
 
+	// === 9.5 Chat persistence (sessions + messages) ===
+	var chatStore *store.ChatStore
+	if database != nil {
+		chatStore = store.NewChatStore(database)
+		ctxStore.SetPersister(&chatPersisterAdapter{s: chatStore})
+		logger.Infof("[chat] session/message persistence ready")
+	}
+
 	// === 10. AI-Core: Sub-session Manager ===
 	subMgr := subsession.NewManager(
 		&subsession.GeneralProvider{},
@@ -238,6 +249,9 @@ func main() {
 	if memSvc != nil {
 		gwDeps.MemorySvc = memory.NewAPIAdapter(memSvc)
 	}
+	if chatStore != nil {
+		gwDeps.ChatStore = chatStore
+	}
 	gwDeps.VoiceSvc = voiceSvc
 
 	wsHub := ws.NewHub(orch)
@@ -331,6 +345,31 @@ func (a *perfAdapter) History() []map[string]any {
 	return result
 }
 
+// chatPersisterAdapter adapts store.ChatStore to aiCoreCtx.Persister.
+type chatPersisterAdapter struct{ s *store.ChatStore }
+
+func (a *chatPersisterAdapter) SaveMessage(sessionID, userID string, msg model.Message) {
+	if userID == "" {
+		userID = "unknown"
+	}
+	if err := a.s.AddMessage(context.Background(), sessionID, userID, msg.Role, msg.Content); err != nil {
+		logger.Infof("[chat] persist message failed: %v", err)
+	}
+}
+
+func (a *chatPersisterAdapter) LoadRecent(sessionID string, limit int) []model.Message {
+	msgs, err := a.s.ListMessages(context.Background(), sessionID, limit)
+	if err != nil {
+		logger.Infof("[chat] load history failed: %v", err)
+		return nil
+	}
+	out := make([]model.Message, len(msgs))
+	for i, m := range msgs {
+		out[i] = model.Message{SessionID: m.SessionID, Role: m.Role, Content: m.Content, CreatedAt: m.CreatedAt}
+	}
+	return out
+}
+
 // toolExecAdapter adapts the plugin registry to orchestrator.ToolExecutor.
 type toolExecAdapter struct{ reg *plugin.Registry }
 
@@ -389,7 +428,7 @@ func loadAdaptersFromConfig(router *bridge.Router, cfg *bridge.BridgeConfig, orc
 
 	router.SetMessageHandler(func(msg *bridge.UnifiedMessage) {
 		sessionID := "bridge-" + msg.Source
-		tokenCh, _, err := orch.ProcessInput(context.Background(), sessionID, msg.Content)
+		tokenCh, _, err := orch.ProcessInput(context.Background(), sessionID, msg.SenderID, msg.Content)
 		if err != nil { return }
 		var fc string
 		for t := range tokenCh { fc += t.Content }

backend/services/ai-core/context/context.go

@@ -10,12 +10,23 @@ import (
 	"git.yeij.top/AskaEth/Cyrene_v2/services/ai-core/model"
 )
 
+// Persister saves conversation messages durably and can restore them
+// (e.g. from PostgreSQL) when a session is not in memory.
+type Persister interface {
+	// SaveMessage persists one message. Called synchronously by Add —
+	// implementations should be fast or dispatch async work themselves.
+	SaveMessage(sessionID, userID string, msg model.Message)
+	// LoadRecent returns the most recent messages of a session, ascending.
+	LoadRecent(sessionID string, limit int) []model.Message
+}
+
 // Store holds conversation history with a sliding window.
 type Store struct {
 	mu       sync.RWMutex
 	sessions map[string]*SessionHistory
 	maxTokens int // Maximum tokens to include in context
 	maxTurns  int // Maximum message turns to keep
+	persister Persister
 }
 
 // SessionHistory holds messages for a single session.
@@ -39,14 +50,31 @@ func NewStore(maxTokens, maxTurns int) *Store {
 	}
 }
 
+// SetPersister injects durable persistence for conversation messages.
+func (s *Store) SetPersister(p Persister) {
+	s.mu.Lock()
+	s.persister = p
+	s.mu.Unlock()
+}
+
 // Add appends a message to the session history.
 func (s *Store) Add(sessionID string, msg model.Message) {
+	s.add(sessionID, "", msg)
+}
+
+// AddWithUser appends a message and records the owning user for persistence.
+func (s *Store) AddWithUser(sessionID, userID string, msg model.Message) {
+	s.add(sessionID, userID, msg)
+}
+
+func (s *Store) add(sessionID, userID string, msg model.Message) {
 	s.mu.Lock()
 	sh, ok := s.sessions[sessionID]
 	if !ok {
 		sh = &SessionHistory{}
 		s.sessions[sessionID] = sh
 	}
+	persister := s.persister
 	s.mu.Unlock()
 
 	sh.mu.Lock()
@@ -56,15 +84,33 @@ func (s *Store) Add(sessionID string, msg model.Message) {
 		sh.Messages = sh.Messages[len(sh.Messages)-s.maxTurns:]
 	}
 	sh.mu.Unlock()
+
+	// Persist asynchronously — never block the conversation on the database.
+	if persister != nil && (msg.Role == "user" || msg.Role == "assistant") {
+		go persister.SaveMessage(sessionID, userID, msg)
+	}
 }
 
 // Get retrieves recent messages for a session, trimmed to fit token budget.
+// Sessions missing from memory are restored from the persister if available.
 func (s *Store) Get(sessionID string) []model.Message {
 	s.mu.RLock()
 	sh, ok := s.sessions[sessionID]
+	persister := s.persister
 	s.mu.RUnlock()
+
 	if !ok {
-		return nil
+		if persister == nil {
+			return nil
+		}
+		loaded := persister.LoadRecent(sessionID, s.maxTurns)
+		if len(loaded) == 0 {
+			return nil
+		}
+		sh = &SessionHistory{Messages: loaded}
+		s.mu.Lock()
+		s.sessions[sessionID] = sh
+		s.mu.Unlock()
 	}
 
 	sh.mu.RLock()

backend/services/ai-core/context/context_test.go

@@ -0,0 +1,98 @@
+package context
+
+import (
+	"sync"
+	"testing"
+	"time"
+
+	"git.yeij.top/AskaEth/Cyrene_v2/services/ai-core/model"
+)
+
+// fakePersister records saved messages and can restore them.
+type fakePersister struct {
+	mu     sync.Mutex
+	saved  map[string][]model.Message
+}
+
+func newFakePersister() *fakePersister {
+	return &fakePersister{saved: map[string][]model.Message{}}
+}
+
+func (f *fakePersister) SaveMessage(sessionID, userID string, msg model.Message) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.saved[sessionID] = append(f.saved[sessionID], msg)
+}
+
+func (f *fakePersister) LoadRecent(sessionID string, limit int) []model.Message {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	return f.saved[sessionID]
+}
+
+func (f *fakePersister) count(sessionID string) int {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	return len(f.saved[sessionID])
+}
+
+func TestPersisterSaveOnAdd(t *testing.T) {
+	s := NewStore(4000, 50)
+	p := newFakePersister()
+	s.SetPersister(p)
+
+	s.AddWithUser("s1", "u1", model.Message{Role: "user", Content: "你好"})
+
+	// SaveMessage is dispatched asynchronously — wait briefly
+	for i := 0; i < 50 && p.count("s1") == 0; i++ {
+		time.Sleep(10 * time.Millisecond)
+	}
+	if p.count("s1") != 1 {
+		t.Fatalf("expected 1 persisted message, got %d", p.count("s1"))
+	}
+}
+
+func TestPersisterSkipsNonChatRoles(t *testing.T) {
+	s := NewStore(4000, 50)
+	p := newFakePersister()
+	s.SetPersister(p)
+
+	s.Add("s1", model.Message{Role: "system", Content: "上下文块"})
+	time.Sleep(50 * time.Millisecond)
+	if p.count("s1") != 0 {
+		t.Fatalf("system messages should not be persisted, got %d", p.count("s1"))
+	}
+}
+
+func TestRestoreFromPersisterOnGet(t *testing.T) {
+	s := NewStore(4000, 50)
+	p := newFakePersister()
+	p.saved["s2"] = []model.Message{
+		{Role: "user", Content: "以前说过的话"},
+		{Role: "assistant", Content: "以前的回复"},
+	}
+	s.SetPersister(p)
+
+	// Session not in memory — should restore from persister
+	msgs := s.Get("s2")
+	if len(msgs) != 2 {
+		t.Fatalf("expected 2 restored messages, got %d", len(msgs))
+	}
+	if msgs[0].Content != "以前说过的话" {
+		t.Errorf("unexpected restored content: %q", msgs[0].Content)
+	}
+
+	// Second Get should hit memory, not reload
+	p.saved["s2"] = nil
+	msgs = s.Get("s2")
+	if len(msgs) != 2 {
+		t.Errorf("expected cached messages after restore, got %d", len(msgs))
+	}
+}
+
+func TestGetWithoutPersister(t *testing.T) {
+	s := NewStore(4000, 50)
+	if msgs := s.Get("missing"); msgs != nil {
+		t.Errorf("expected nil for unknown session, got %v", msgs)
+	}
+}

backend/services/ai-core/orchestrator/orchestrator.go

@@ -79,7 +79,7 @@ func (p *Pipeline) SetToolExecutor(t ToolExecutor) {
 
 // ProcessInput processes a user message through the full pipeline.
 // Returns a channel of StreamToken for the LLM response.
-func (p *Pipeline) ProcessInput(ctx context.Context, sessionID, userMessage string) (<-chan model.StreamToken, *model.Intent, error) {
+func (p *Pipeline) ProcessInput(ctx context.Context, sessionID, userID, userMessage string) (<-chan model.StreamToken, *model.Intent, error) {
 	// 1. Cache check
 	if cached := p.cache.Get(userMessage); cached != nil {
 		ch := make(chan model.StreamToken, 1)
@@ -122,7 +122,7 @@ func (p *Pipeline) ProcessInput(ctx context.Context, sessionID, userMessage stri
 	}
 
 	// 7. Store user message
-	p.ctxStore.Add(sessionID, model.Message{Role: "user", Content: userMessage})
+	p.ctxStore.AddWithUser(sessionID, userID, model.Message{Role: "user", Content: userMessage})
 
 	return tokenCh, intent, nil
 }
@@ -193,7 +193,7 @@ func (p *Pipeline) streamWithTools(ctx context.Context, adapter *llm.Adapter, me
 // after the response stream completes.
 func (p *Pipeline) FinishRound(sessionID, userID, assistantReply string) {
 	if assistantReply != "" {
-		p.ctxStore.Add(sessionID, model.Message{Role: "assistant", Content: assistantReply})
+		p.ctxStore.AddWithUser(sessionID, userID, model.Message{Role: "assistant", Content: assistantReply})
 	}
 	p.PostProcess(sessionID, userID)
 }

backend/services/ai-core/orchestrator/orchestrator_tools_test.go

@@ -87,7 +87,7 @@ func TestToolCallLoop(t *testing.T) {
 	exec := &fakeToolExec{}
 	p.SetToolExecutor(exec)
 
-	tokenCh, _, err := p.ProcessInput(context.Background(), "s1", "打开客厅灯")
+	tokenCh, _, err := p.ProcessInput(context.Background(), "s1", "u1", "打开客厅灯")
 	if err != nil {
 		t.Fatalf("ProcessInput: %v", err)
 	}

backend/services/gateway/api/handlers_more.go

@@ -166,20 +166,60 @@ func (r *Router) notificationHandler(w http.ResponseWriter, req *http.Request) {
 
 func (r *Router) messageSearchHandler(w http.ResponseWriter, req *http.Request) {
 	q := req.URL.Query().Get("q")
-	uid := req.Header.Get("X-User-ID")
+	uid := r.userID(req)
 	if q == "" { writeJSON(w, 400, M{"error": "missing query"}); return }
-	// Uses session store DB — returns matching messages
-	writeJSON(w, 200, M{"messages": []any{}, "query": q, "user_id": uid, "total": 0})
+	if r.deps.ChatStore == nil { writeJSON(w, 503, M{"error": "chat store unavailable"}); return }
+
+	messages, err := r.deps.ChatStore.SearchMessages(req.Context(), uid, q, 20)
+	if err != nil {
+		writeJSON(w, 500, M{"error": err.Error()})
+		return
+	}
+	writeJSON(w, 200, M{"messages": messages, "query": q, "total": len(messages)})
 }
 
 func (r *Router) sessionExportHandler(w http.ResponseWriter, req *http.Request) {
-	id := strings.TrimPrefix(req.URL.Path, "/api/v1/sessions/")
-	id = strings.TrimSuffix(id, "/export")
-	// Export session as markdown
-	w.Header().Set("Content-Type", "text/markdown; charset=utf-8")
-	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=session-%s.md", id[:8]))
-	w.WriteHeader(200)
-	fmt.Fprintf(w, "# Cyrene Chat - Session %s\n\n*Exported at %s*\n\n", id[:8], time.Now().Format(time.RFC3339))
+	id := strings.TrimSuffix(strings.TrimPrefix(req.URL.Path, "/api/v1/sessions/"), "/export")
+	if r.deps.ChatStore == nil { writeJSON(w, 503, M{"error": "chat store unavailable"}); return }
+
+	messages, err := r.deps.ChatStore.ListMessages(req.Context(), id, 200)
+	if err != nil {
+		writeJSON(w, 500, M{"error": err.Error()})
+		return
+	}
+
+	short := id
+	if len(short) > 8 { short = short[:8] }
+	format := req.URL.Query().Get("format")
+	exportedAt := time.Now().Format(time.RFC3339)
+
+	switch format {
+	case "json":
+		w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=session-%s.json", short))
+		writeJSON(w, 200, M{"session_id": id, "exported_at": exportedAt, "messages": messages})
+	case "txt":
+		var sb strings.Builder
+		fmt.Fprintf(&sb, "Cyrene Chat - Session %s (exported %s)\n\n", short, exportedAt)
+		for _, m := range messages {
+			fmt.Fprintf(&sb, "[%s] %s: %s\n\n", m.CreatedAt.Format("2006-01-02 15:04"), m.Role, m.Content)
+		}
+		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+		w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=session-%s.txt", short))
+		w.WriteHeader(200)
+		w.Write([]byte(sb.String()))
+	default: // markdown
+		var sb strings.Builder
+		fmt.Fprintf(&sb, "# Cyrene Chat - Session %s\n\n*Exported at %s*\n\n", short, exportedAt)
+		for _, m := range messages {
+			who := "用户"
+			if m.Role == "assistant" { who = "昔涟" }
+			fmt.Fprintf(&sb, "**%s**（%s）：\n\n%s\n\n---\n\n", who, m.CreatedAt.Format("2006-01-02 15:04"), m.Content)
+		}
+		w.Header().Set("Content-Type", "text/markdown; charset=utf-8")
+		w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=session-%s.md", short))
+		w.WriteHeader(200)
+		w.Write([]byte(sb.String()))
+	}
 }
 
 func (r *Router) imageAnalyzeHandler(w http.ResponseWriter, req *http.Request) {

backend/services/gateway/api/router.go

@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"git.yeij.top/AskaEth/Cyrene_v2/services/ai-core/model"
+	"git.yeij.top/AskaEth/Cyrene_v2/services/gateway/store"
 )
 
 // --- Interfaces for injected services ---
@@ -51,7 +52,7 @@ type VoiceService interface {
 
 // OrchestratorPipeline handles the main dialogue flow.
 type OrchestratorPipeline interface {
-	ProcessInput(ctx context.Context, sessionID, userMessage string) (<-chan model.StreamToken, *model.Intent, error)
+	ProcessInput(ctx context.Context, sessionID, userID, userMessage string) (<-chan model.StreamToken, *model.Intent, error)
 }
 
 // WebSocketHub manages WS connections.
@@ -85,6 +86,16 @@ type BridgeConfigManager interface {
 	DeleteAdapter(name string) error
 }
 
+// ChatStorer persists chat sessions and messages.
+type ChatStorer interface {
+	CreateSession(ctx context.Context, id, userID, title string) (*store.Session, error)
+	ListSessions(ctx context.Context, userID string) ([]store.Session, error)
+	DeleteSession(ctx context.Context, id, userID string) error
+	ListMessages(ctx context.Context, sessionID string, limit int) ([]store.Message, error)
+	ClearMessages(ctx context.Context, sessionID string) error
+	SearchMessages(ctx context.Context, userID, query string, limit int) ([]store.Message, error)
+}
+
 // Dependencies holds all injectable services.
 type Dependencies struct {
 	AuthMgr      AuthManager
@@ -96,6 +107,7 @@ type Dependencies struct {
 	TraceLog     TraceLogger
 	PerfMon      PerfMonitor
 	BridgeCfg    BridgeConfigManager
+	ChatStore    ChatStorer
 	ModelConfig  *ModelConfigStore
 	Automation   *AutomationStore
 	Reminders    *ReminderStore
@@ -257,29 +269,91 @@ func (r *Router) registerHandler(w http.ResponseWriter, req *http.Request) {
 // --- Sessions ---
 
 func (r *Router) sessionsHandler(w http.ResponseWriter, req *http.Request) {
+	if r.deps.ChatStore == nil {
+		writeJSON(w, 503, M{"error": "chat store unavailable"})
+		return
+	}
+	uid := r.userID(req)
 	switch req.Method {
 	case "GET":
-		writeJSON(w, 200, M{"sessions": []any{}})
+		sessions, err := r.deps.ChatStore.ListSessions(req.Context(), uid)
+		if err != nil {
+			writeJSON(w, 500, M{"error": err.Error()})
+			return
+		}
+		writeJSON(w, 200, M{"sessions": sessions})
 	case "POST":
-		writeJSON(w, 201, M{"session_id": randID()})
+		var body struct {
+			Title string `json:"title"`
+		}
+		json.NewDecoder(req.Body).Decode(&body)
+		sess, err := r.deps.ChatStore.CreateSession(req.Context(), randID(), uid, body.Title)
+		if err != nil {
+			writeJSON(w, 500, M{"error": err.Error()})
+			return
+		}
+		writeJSON(w, 201, M{"session_id": sess.ID, "title": sess.Title})
 	default:
 		writeJSON(w, 405, M{"error": "method not allowed"})
 	}
 }
 
 func (r *Router) sessionByIDHandler(w http.ResponseWriter, req *http.Request) {
-	id := strings.TrimPrefix(req.URL.Path, "/api/v1/sessions/")
-	// Handle export
-	if strings.HasSuffix(id, "/export") {
-		id = strings.TrimSuffix(id, "/export")
+	if r.deps.ChatStore == nil {
+		writeJSON(w, 503, M{"error": "chat store unavailable"})
+		return
+	}
+	rest := strings.TrimPrefix(req.URL.Path, "/api/v1/sessions/")
+
+	// Sub-resources: /sessions/{id}/export and /sessions/{id}/messages
+	if strings.HasSuffix(rest, "/export") {
 		r.sessionExportHandler(w, req)
 		return
 	}
+	if strings.HasSuffix(rest, "/messages") {
+		r.sessionMessagesHandler(w, req)
+		return
+	}
+
+	id := rest
 	switch req.Method {
 	case "DELETE":
+		if err := r.deps.ChatStore.DeleteSession(req.Context(), id, r.userID(req)); err != nil {
+			writeJSON(w, 404, M{"error": err.Error()})
+			return
+		}
 		writeJSON(w, 204, nil)
 	case "GET":
-		writeJSON(w, 200, M{"session_id": id})
+		messages, err := r.deps.ChatStore.ListMessages(req.Context(), id, 100)
+		if err != nil {
+			writeJSON(w, 500, M{"error": err.Error()})
+			return
+		}
+		writeJSON(w, 200, M{"session_id": id, "messages": messages})
+	default:
+		writeJSON(w, 405, M{"error": "method not allowed"})
+	}
+}
+
+// sessionMessagesHandler serves GET (recent history) and DELETE (clear).
+func (r *Router) sessionMessagesHandler(w http.ResponseWriter, req *http.Request) {
+	id := strings.TrimSuffix(strings.TrimPrefix(req.URL.Path, "/api/v1/sessions/"), "/messages")
+	switch req.Method {
+	case "GET":
+		limit := 0
+		fmt.Sscanf(req.URL.Query().Get("limit"), "%d", &limit)
+		messages, err := r.deps.ChatStore.ListMessages(req.Context(), id, limit)
+		if err != nil {
+			writeJSON(w, 500, M{"error": err.Error()})
+			return
+		}
+		writeJSON(w, 200, M{"messages": messages})
+	case "DELETE":
+		if err := r.deps.ChatStore.ClearMessages(req.Context(), id); err != nil {
+			writeJSON(w, 500, M{"error": err.Error()})
+			return
+		}
+		writeJSON(w, 204, nil)
 	default:
 		writeJSON(w, 405, M{"error": "method not allowed"})
 	}

backend/services/gateway/api/router_test.go

@@ -25,7 +25,7 @@ func TestHealth(t *testing.T) {
 
 func TestLoginAndProtectedEndpoint(t *testing.T) {
 	auth := NewStubAuthManager()
-	r := New(Dependencies{AuthMgr: auth})
+	r := New(Dependencies{AuthMgr: auth, ChatStore: newFakeChatStore()})
 	srv := httptest.NewServer(r)
 	defer srv.Close()
 

backend/services/gateway/api/sessions_test.go

@@ -0,0 +1,239 @@
+package api
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"git.yeij.top/AskaEth/Cyrene_v2/services/gateway/store"
+)
+
+// fakeChatStore is an in-memory ChatStorer for tests.
+type fakeChatStore struct {
+	mu       sync.Mutex
+	sessions map[string]*store.Session
+	messages map[string][]store.Message
+	nextID   int64
+}
+
+func newFakeChatStore() *fakeChatStore {
+	return &fakeChatStore{sessions: map[string]*store.Session{}, messages: map[string][]store.Message{}}
+}
+
+func (f *fakeChatStore) CreateSession(_ context.Context, id, userID, title string) (*store.Session, error) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	s := &store.Session{ID: id, UserID: userID, Title: title, CreatedAt: time.Now(), UpdatedAt: time.Now()}
+	f.sessions[id] = s
+	return s, nil
+}
+
+func (f *fakeChatStore) ListSessions(_ context.Context, userID string) ([]store.Session, error) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	out := []store.Session{}
+	for _, s := range f.sessions {
+		if s.UserID == userID {
+			out = append(out, *s)
+		}
+	}
+	return out, nil
+}
+
+func (f *fakeChatStore) DeleteSession(_ context.Context, id, userID string) error {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	if _, ok := f.sessions[id]; !ok {
+		return fmt.Errorf("session not found")
+	}
+	delete(f.sessions, id)
+	delete(f.messages, id)
+	return nil
+}
+
+func (f *fakeChatStore) AddMessage(sessionID, role, content string) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.nextID++
+	f.messages[sessionID] = append(f.messages[sessionID], store.Message{
+		ID: f.nextID, SessionID: sessionID, Role: role, Content: content, CreatedAt: time.Now(),
+	})
+}
+
+func (f *fakeChatStore) ListMessages(_ context.Context, sessionID string, limit int) ([]store.Message, error) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	msgs := f.messages[sessionID]
+	if msgs == nil {
+		msgs = []store.Message{}
+	}
+	return msgs, nil
+}
+
+func (f *fakeChatStore) ClearMessages(_ context.Context, sessionID string) error {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.messages[sessionID] = nil
+	return nil
+}
+
+func (f *fakeChatStore) SearchMessages(_ context.Context, userID, query string, limit int) ([]store.Message, error) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	out := []store.Message{}
+	for _, msgs := range f.messages {
+		for _, m := range msgs {
+			if strings.Contains(m.Content, query) {
+				out = append(out, m)
+			}
+		}
+	}
+	return out, nil
+}
+
+func authReq(method, url, body string) *http.Request {
+	var r *http.Request
+	if body != "" {
+		r, _ = http.NewRequest(method, url, strings.NewReader(body))
+		r.Header.Set("Content-Type", "application/json")
+	} else {
+		r, _ = http.NewRequest(method, url, nil)
+	}
+	r.Header.Set("Authorization", "Bearer stub-token-admin")
+	return r
+}
+
+func TestSessionLifecycle(t *testing.T) {
+	auth := NewStubAuthManager()
+	auth.Login("admin", "admin") // register stub-token-admin
+	chat := newFakeChatStore()
+	r := New(Dependencies{AuthMgr: auth, ChatStore: chat})
+	srv := httptest.NewServer(r)
+	defer srv.Close()
+
+	// Create session
+	resp, err := http.DefaultClient.Do(authReq("POST", srv.URL+"/api/v1/sessions", `{"title":""}`))
+	if err != nil {
+		t.Fatalf("POST sessions: %v", err)
+	}
+	if resp.StatusCode != http.StatusCreated {
+		t.Fatalf("create: expected 201, got %d", resp.StatusCode)
+	}
+	var created struct {
+		SessionID string `json:"session_id"`
+	}
+	readJSON(t, resp, &created)
+	if created.SessionID == "" {
+		t.Fatal("empty session_id")
+	}
+
+	// Seed messages directly
+	chat.AddMessage(created.SessionID, "user", "今晚想吃火锅")
+	chat.AddMessage(created.SessionID, "assistant", "好呀，要不要叫上朋友")
+
+	// List sessions
+	resp, _ = http.DefaultClient.Do(authReq("GET", srv.URL+"/api/v1/sessions", ""))
+	var listed struct {
+		Sessions []store.Session `json:"sessions"`
+	}
+	readJSON(t, resp, &listed)
+	if len(listed.Sessions) != 1 {
+		t.Fatalf("list: expected 1 session, got %d", len(listed.Sessions))
+	}
+
+	// Get messages
+	resp, _ = http.DefaultClient.Do(authReq("GET", srv.URL+"/api/v1/sessions/"+created.SessionID+"/messages", ""))
+	var msgs struct {
+		Messages []store.Message `json:"messages"`
+	}
+	readJSON(t, resp, &msgs)
+	if len(msgs.Messages) != 2 {
+		t.Fatalf("messages: expected 2, got %d", len(msgs.Messages))
+	}
+
+	// Search
+	resp, _ = http.DefaultClient.Do(authReq("GET", srv.URL+"/api/v1/messages/search?q=火锅", ""))
+	var found struct {
+		Total int `json:"total"`
+	}
+	readJSON(t, resp, &found)
+	if found.Total != 1 {
+		t.Errorf("search: expected 1 hit, got %d", found.Total)
+	}
+
+	// Export markdown
+	resp, _ = http.DefaultClient.Do(authReq("GET", srv.URL+"/api/v1/sessions/"+created.SessionID+"/export", ""))
+	body := readBody(t, resp)
+	if !strings.Contains(body, "火锅") || !strings.Contains(body, "# Cyrene Chat") {
+		t.Errorf("export markdown missing content: %q", body)
+	}
+
+	// Export json
+	resp, _ = http.DefaultClient.Do(authReq("GET", srv.URL+"/api/v1/sessions/"+created.SessionID+"/export?format=json", ""))
+	var exported struct {
+		Messages []store.Message `json:"messages"`
+	}
+	readJSON(t, resp, &exported)
+	if len(exported.Messages) != 2 {
+		t.Errorf("export json: expected 2 messages, got %d", len(exported.Messages))
+	}
+
+	// Clear messages
+	resp, _ = http.DefaultClient.Do(authReq("DELETE", srv.URL+"/api/v1/sessions/"+created.SessionID+"/messages", ""))
+	if resp.StatusCode != http.StatusNoContent {
+		t.Errorf("clear: expected 204, got %d", resp.StatusCode)
+	}
+	resp.Body.Close()
+
+	// Delete session
+	resp, _ = http.DefaultClient.Do(authReq("DELETE", srv.URL+"/api/v1/sessions/"+created.SessionID, ""))
+	if resp.StatusCode != http.StatusNoContent {
+		t.Errorf("delete: expected 204, got %d", resp.StatusCode)
+	}
+	resp.Body.Close()
+
+	resp, _ = http.DefaultClient.Do(authReq("DELETE", srv.URL+"/api/v1/sessions/"+created.SessionID, ""))
+	if resp.StatusCode != http.StatusNotFound {
+		t.Errorf("delete again: expected 404, got %d", resp.StatusCode)
+	}
+	resp.Body.Close()
+}
+
+func TestSessionsUnavailableWithoutStore(t *testing.T) {
+	auth := NewStubAuthManager()
+	auth.Login("admin", "admin")
+	r := New(Dependencies{AuthMgr: auth})
+	srv := httptest.NewServer(r)
+	defer srv.Close()
+
+	resp, _ := http.DefaultClient.Do(authReq("GET", srv.URL+"/api/v1/sessions", ""))
+	if resp.StatusCode != http.StatusServiceUnavailable {
+		t.Errorf("expected 503 without store, got %d", resp.StatusCode)
+	}
+	resp.Body.Close()
+}
+
+func readJSON(t *testing.T, resp *http.Response, v any) {
+	t.Helper()
+	defer resp.Body.Close()
+	if err := json.NewDecoder(resp.Body).Decode(v); err != nil {
+		t.Fatalf("decode response: %v", err)
+	}
+}
+
+func readBody(t *testing.T, resp *http.Response) string {
+	t.Helper()
+	defer resp.Body.Close()
+	b, err := io.ReadAll(resp.Body)
+	if err != nil {
+		t.Fatalf("read body: %v", err)
+	}
+	return string(b)
+}

backend/services/gateway/store/chat_store.go

@@ -0,0 +1,224 @@
+// Package store provides PostgreSQL persistence for chat sessions and messages.
+package store
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"strings"
+	"time"
+)
+
+// Session represents a chat session.
+type Session struct {
+	ID        string    `json:"id"`
+	UserID    string    `json:"user_id"`
+	Title     string    `json:"title"`
+	CreatedAt time.Time `json:"created_at"`
+	UpdatedAt time.Time `json:"updated_at"`
+}
+
+// Message represents a single chat message.
+type Message struct {
+	ID        int64     `json:"id"`
+	SessionID string    `json:"session_id"`
+	Role      string    `json:"role"` // "user" | "assistant"
+	Content   string    `json:"content"`
+	CreatedAt time.Time `json:"created_at"`
+}
+
+// ChatStore persists sessions and messages in PostgreSQL.
+type ChatStore struct {
+	db *sql.DB
+}
+
+// NewChatStore creates a store backed by the given database.
+func NewChatStore(db *sql.DB) *ChatStore {
+	return &ChatStore{db: db}
+}
+
+// CreateTableSQL returns the schema for session/message persistence.
+func CreateTableSQL() string {
+	return `
+CREATE TABLE IF NOT EXISTS chat_sessions (
+    id         TEXT PRIMARY KEY,
+    user_id    TEXT NOT NULL,
+    title      TEXT NOT NULL DEFAULT '',
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+CREATE INDEX IF NOT EXISTS idx_chat_sessions_user ON chat_sessions(user_id, updated_at DESC);
+
+CREATE TABLE IF NOT EXISTS chat_messages (
+    id         BIGSERIAL PRIMARY KEY,
+    session_id TEXT NOT NULL REFERENCES chat_sessions(id) ON DELETE CASCADE,
+    user_id    TEXT NOT NULL,
+    role       TEXT NOT NULL,
+    content    TEXT NOT NULL,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+CREATE INDEX IF NOT EXISTS idx_chat_messages_session ON chat_messages(session_id, id);
+CREATE INDEX IF NOT EXISTS idx_chat_messages_user ON chat_messages(user_id, id);
+`
+}
+
+// --- Sessions ---
+
+// CreateSession creates a new session for the user.
+func (s *ChatStore) CreateSession(ctx context.Context, id, userID, title string) (*Session, error) {
+	sess := &Session{ID: id, UserID: userID, Title: title}
+	err := s.db.QueryRowContext(ctx, `
+		INSERT INTO chat_sessions (id, user_id, title) VALUES ($1, $2, $3)
+		RETURNING created_at, updated_at
+	`, id, userID, title).Scan(&sess.CreatedAt, &sess.UpdatedAt)
+	if err != nil {
+		return nil, fmt.Errorf("create session: %w", err)
+	}
+	return sess, nil
+}
+
+// ListSessions returns the user's sessions, most recently active first.
+func (s *ChatStore) ListSessions(ctx context.Context, userID string) ([]Session, error) {
+	rows, err := s.db.QueryContext(ctx, `
+		SELECT id, user_id, title, created_at, updated_at
+		FROM chat_sessions WHERE user_id = $1
+		ORDER BY updated_at DESC LIMIT 100
+	`, userID)
+	if err != nil {
+		return nil, fmt.Errorf("list sessions: %w", err)
+	}
+	defer rows.Close()
+
+	sessions := []Session{}
+	for rows.Next() {
+		var sess Session
+		if err := rows.Scan(&sess.ID, &sess.UserID, &sess.Title, &sess.CreatedAt, &sess.UpdatedAt); err != nil {
+			return nil, err
+		}
+		sessions = append(sessions, sess)
+	}
+	return sessions, rows.Err()
+}
+
+// DeleteSession removes a session and its messages (CASCADE).
+func (s *ChatStore) DeleteSession(ctx context.Context, id, userID string) error {
+	res, err := s.db.ExecContext(ctx, `DELETE FROM chat_sessions WHERE id = $1 AND user_id = $2`, id, userID)
+	if err != nil {
+		return fmt.Errorf("delete session: %w", err)
+	}
+	if n, _ := res.RowsAffected(); n == 0 {
+		return fmt.Errorf("session not found")
+	}
+	return nil
+}
+
+// --- Messages ---
+
+// AddMessage appends a message, creating the session row if needed and
+// bumping updated_at. The first user message becomes the session title.
+func (s *ChatStore) AddMessage(ctx context.Context, sessionID, userID, role, content string) error {
+	tx, err := s.db.BeginTx(ctx, nil)
+	if err != nil {
+		return fmt.Errorf("begin tx: %w", err)
+	}
+	defer tx.Rollback()
+
+	if _, err := tx.ExecContext(ctx, `
+		INSERT INTO chat_sessions (id, user_id) VALUES ($1, $2) ON CONFLICT (id) DO NOTHING
+	`, sessionID, userID); err != nil {
+		return fmt.Errorf("ensure session: %w", err)
+	}
+
+	if _, err := tx.ExecContext(ctx, `
+		INSERT INTO chat_messages (session_id, user_id, role, content) VALUES ($1, $2, $3, $4)
+	`, sessionID, userID, role, content); err != nil {
+		return fmt.Errorf("insert message: %w", err)
+	}
+
+	title := ""
+	if role == "user" {
+		title = truncateRunes(strings.TrimSpace(content), 24)
+	}
+	if _, err := tx.ExecContext(ctx, `
+		UPDATE chat_sessions SET
+			updated_at = now(),
+			title = CASE WHEN title = '' AND $3 <> '' THEN $3 ELSE title END
+		WHERE id = $1 AND user_id = $2
+	`, sessionID, userID, title); err != nil {
+		return fmt.Errorf("touch session: %w", err)
+	}
+
+	return tx.Commit()
+}
+
+// ListMessages returns the most recent messages of a session (ascending order).
+func (s *ChatStore) ListMessages(ctx context.Context, sessionID string, limit int) ([]Message, error) {
+	if limit <= 0 || limit > 200 {
+		limit = 100
+	}
+	rows, err := s.db.QueryContext(ctx, `
+		SELECT id, session_id, role, content, created_at FROM (
+			SELECT id, session_id, role, content, created_at
+			FROM chat_messages WHERE session_id = $1
+			ORDER BY id DESC LIMIT $2
+		) recent ORDER BY id ASC
+	`, sessionID, limit)
+	if err != nil {
+		return nil, fmt.Errorf("list messages: %w", err)
+	}
+	defer rows.Close()
+
+	messages := []Message{}
+	for rows.Next() {
+		var m Message
+		if err := rows.Scan(&m.ID, &m.SessionID, &m.Role, &m.Content, &m.CreatedAt); err != nil {
+			return nil, err
+		}
+		messages = append(messages, m)
+	}
+	return messages, rows.Err()
+}
+
+// ClearMessages removes all messages of a session.
+func (s *ChatStore) ClearMessages(ctx context.Context, sessionID string) error {
+	_, err := s.db.ExecContext(ctx, `DELETE FROM chat_messages WHERE session_id = $1`, sessionID)
+	return err
+}
+
+// SearchMessages does a substring search across the user's messages.
+func (s *ChatStore) SearchMessages(ctx context.Context, userID, query string, limit int) ([]Message, error) {
+	if limit <= 0 || limit > 100 {
+		limit = 20
+	}
+	rows, err := s.db.QueryContext(ctx, `
+		SELECT id, session_id, role, content, created_at
+		FROM chat_messages
+		WHERE user_id = $1 AND content ILIKE '%' || $2 || '%'
+		ORDER BY id DESC LIMIT $3
+	`, userID, query, limit)
+	if err != nil {
+		return nil, fmt.Errorf("search messages: %w", err)
+	}
+	defer rows.Close()
+
+	messages := []Message{}
+	for rows.Next() {
+		var m Message
+		if err := rows.Scan(&m.ID, &m.SessionID, &m.Role, &m.Content, &m.CreatedAt); err != nil {
+			return nil, err
+		}
+		messages = append(messages, m)
+	}
+	return messages, rows.Err()
+}
+
+// --- Helpers ---
+
+// truncateRunes cuts s to at most n runes, appending an ellipsis when cut.
+func truncateRunes(s string, n int) string {
+	runes := []rune(s)
+	if len(runes) <= n {
+		return s
+	}
+	return string(runes[:n]) + "…"
+}

backend/services/gateway/ws/hub.go

@@ -22,7 +22,7 @@ var upgrader = websocket.Upgrader{
 
 // Orchestrator is the interface for the AI dialogue pipeline.
 type Orchestrator interface {
-	ProcessInput(ctx context.Context, sessionID, userMessage string) (<-chan model.StreamToken, *model.Intent, error)
+	ProcessInput(ctx context.Context, sessionID, userID, userMessage string) (<-chan model.StreamToken, *model.Intent, error)
 	// FinishRound records the assistant reply and triggers post-round work
 	// (e.g. memory extraction) after the response stream completes.
 	FinishRound(sessionID, userID, assistantReply string)
@@ -160,7 +160,7 @@ func (c *Client) handleChatMessage(msg WSMessage) {
 	}
 
 	// Call orchestrator
-	tokenCh, intent, err := c.hub.orchestrator.ProcessInput(context.Background(), msg.SessionID, msg.Content)
+	tokenCh, intent, err := c.hub.orchestrator.ProcessInput(context.Background(), msg.SessionID, c.UserID, msg.Content)
 	if err != nil {
 		c.sendJSON(WSMessage{Type: "error", Error: err.Error()})
 		return