feat(gateway): 会话title生成+PATCH改名(A4) — 首条用户消息自动命名+可重命名

- history/title.go: RenameSession(改名字段)+ensureTitle(首条用户消息自动命名,折叠空白取前20rune,纯空白回落主会话/次级会话)
- store.go insert() 前调用 ensureTitle(覆盖Web+IM,最小侵入), HistoryStore 新增 RenameSession
- gateway: PATCH /api/v1/sessions/{id} (owner/admin, ≤80rune, 主会话可改名), handleRenameSession
- 新增/扩展测试(title_test, history_handler_test, fake同步)
- Docs/api-client.md v0.21 同步

internal/services/channelbridge/channelbridge_test.go

@@ -276,6 +276,9 @@ func (c *captureHistory) ListAllLog(context.Context, int64, int) ([]history.Mess
 	return nil, nil
 }
 func (c *captureHistory) DeleteSession(context.Context, string) error { return nil }
+func (c *captureHistory) RenameSession(context.Context, string, string) error {
+	return nil
+}
 func (c *captureHistory) NewSubSession(context.Context, string) (string, error) {
 	return "", nil
 }

internal/services/gateway/history.go

@@ -1,9 +1,12 @@
 package gateway
 
 import (
+	"encoding/json"
 	"errors"
 	"net/http"
 	"strconv"
+	"strings"
+	"unicode/utf8"
 
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/auth"
 	apperr "git.yeij.top/AskaEth/Cyrene_v2/internal/errors"
@@ -257,6 +260,57 @@ func (s *Server) handleDeleteSession(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, http.StatusOK, map[string]any{"deleted": id})
 }
 
+// renameSessionRequest is the PATCH /api/v1/sessions/{id} body.
+type renameSessionRequest struct {
+	Title string `json:"title"`
+}
+
+// maxSessionTitleRunes bounds a client-supplied session title so a display row never
+// overflows. It is a display-only bound: identity and permissions never derive from
+// the title (project red line).
+const maxSessionTitleRunes = 80
+
+// handleRenameSession renames a persistent session (main or sub). The title is
+// display-only metadata, so unlike DELETE it is allowed on the fixed main session. An
+// empty/whitespace title or one longer than maxSessionTitleRunes answers 400; an
+// unknown session id answers 404. It is owner/admin-gated like the other history
+// writes.
+func (s *Server) handleRenameSession(w http.ResponseWriter, r *http.Request) {
+	if s.history == nil {
+		writeError(w, &apperr.AppError{Code: "not_implemented", Message: "会话历史服务未配置（未注入 HistoryStore）", HTTPCode: http.StatusNotImplemented})
+		return
+	}
+	id := r.PathValue("id")
+	if id == "" {
+		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "session id is required"))
+		return
+	}
+	var req renameSessionRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "invalid request body"))
+		return
+	}
+	title := strings.TrimSpace(req.Title)
+	if title == "" {
+		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "title is required"))
+		return
+	}
+	if utf8.RuneCountInString(title) > maxSessionTitleRunes {
+		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "title is too long (max 80 characters)"))
+		return
+	}
+	if err := s.history.RenameSession(r.Context(), id, title); err != nil {
+		if errors.Is(err, history.ErrSessionNotFound) {
+			writeError(w, apperr.Wrap(apperr.ErrNotFound, "not_found", "session %q not found", id))
+			return
+		}
+		s.log.Error("history rename session", "err", err, "session", id)
+		writeError(w, apperr.Wrap(apperr.ErrInternal, "session_failed", "failed to rename session"))
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"id": id, "title": title})
+}
+
 // toHistoryMessage maps a stored history.Message to its wire shape.
 func toHistoryMessage(m history.Message) historyMessage {
 	return historyMessage{

internal/services/gateway/history_handler_test.go

@@ -13,6 +13,7 @@ import (
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/auth"
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/db"
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/history"
+	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/model"
 )
 
 // testLogger returns a logger that writes nowhere, keeping test output clean.
@@ -284,6 +285,154 @@ func TestHistoryDeleteSubSession(t *testing.T) {
 	wantErrorShape(t, body)
 }
 
+// TestHistoryRenameSession covers PATCH /api/v1/sessions/{id}: renaming a sub and
+// the fixed main session, the input bounds, RBAC and an unknown id.
+func TestHistoryRenameSession(t *testing.T) {
+	t.Parallel()
+	_, ts, jwt, _ := newHistoryEnv(t)
+	tok := signAny(t, jwt, "acct", auth.RoleOwner)
+
+	// Create a sub session to rename.
+	resp, body := doReq(t, http.MethodPost, ts.URL+"/api/v1/sessions", nil, tok)
+	if resp.StatusCode != http.StatusCreated {
+		t.Fatalf("create status = %d, want 201 (body=%s)", resp.StatusCode, body)
+	}
+	var created struct {
+		SessionID string `json:"sessionId"`
+	}
+	if err := json.Unmarshal(decodeBody(t, body)["data"], &created); err != nil {
+		t.Fatalf("decode create data: %v", err)
+	}
+
+	// Rename it and assert the response envelope plus the persisted list.
+	resp, body = doReq(t, http.MethodPatch, ts.URL+"/api/v1/sessions/"+created.SessionID, map[string]any{"title": "  我的会话  "}, tok)
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("rename status = %d, want 200 (body=%s)", resp.StatusCode, body)
+	}
+	var renamed struct {
+		ID    string `json:"id"`
+		Title string `json:"title"`
+	}
+	if err := json.Unmarshal(decodeBody(t, body)["data"], &renamed); err != nil {
+		t.Fatalf("decode rename data: %v", err)
+	}
+	if renamed.ID != created.SessionID || renamed.Title != "我的会话" {
+		t.Fatalf("rename data = %+v, want id %s title 我的会话", renamed, created.SessionID)
+	}
+	resp, body = doReq(t, http.MethodGet, ts.URL+"/api/v1/sessions", nil, tok)
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("list status = %d, want 200 (body=%s)", resp.StatusCode, body)
+	}
+	var sessions []historySessionSummary
+	decodeDataSlice(t, body, &sessions)
+	found := false
+	for _, m := range sessions {
+		if m.ID == created.SessionID {
+			found = true
+			if m.Title != "我的会话" {
+				t.Fatalf("listed sub title = %q, want 我的会话", m.Title)
+			}
+		}
+	}
+	if !found {
+		t.Fatalf("renamed sub %s missing from %+v", created.SessionID, sessions)
+	}
+
+	// The fixed main session may be renamed even though it cannot be deleted.
+	resp, body = doReq(t, http.MethodPatch, ts.URL+"/api/v1/sessions/"+history.MainSessionID, map[string]any{"title": "主控台"}, tok)
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("rename main status = %d, want 200 (body=%s)", resp.StatusCode, body)
+	}
+	var mainRenamed struct {
+		ID    string `json:"id"`
+		Title string `json:"title"`
+	}
+	if err := json.Unmarshal(decodeBody(t, body)["data"], &mainRenamed); err != nil {
+		t.Fatalf("decode main rename data: %v", err)
+	}
+	if mainRenamed.ID != history.MainSessionID || mainRenamed.Title != "主控台" {
+		t.Fatalf("main rename data = %+v, want id web title 主控台", mainRenamed)
+	}
+
+	// Empty / whitespace-only / over-long titles are 400.
+	for _, bad := range []string{"", "   ", strings.Repeat("字", maxSessionTitleRunes+1)} {
+		resp, body = doReq(t, http.MethodPatch, ts.URL+"/api/v1/sessions/"+created.SessionID, map[string]any{"title": bad}, tok)
+		if resp.StatusCode != http.StatusBadRequest {
+			t.Fatalf("title %q status = %d, want 400 (body=%s)", bad, resp.StatusCode, body)
+		}
+		wantErrorShape(t, body)
+	}
+
+	// An unknown session id is 404.
+	resp, body = doReq(t, http.MethodPatch, ts.URL+"/api/v1/sessions/web:missing", map[string]any{"title": "x"}, tok)
+	if resp.StatusCode != http.StatusNotFound {
+		t.Fatalf("unknown rename status = %d, want 404 (body=%s)", resp.StatusCode, body)
+	}
+
+	// A title of exactly the 80-rune bound is accepted.
+	exact := strings.Repeat("字", maxSessionTitleRunes)
+	resp, body = doReq(t, http.MethodPatch, ts.URL+"/api/v1/sessions/"+created.SessionID, map[string]any{"title": exact}, tok)
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("80-rune rename status = %d, want 200 (body=%s)", resp.StatusCode, body)
+	}
+
+	// A viewer cannot rename (owner/admin write).
+	viewer := signAny(t, jwt, "acct", auth.RoleViewer)
+	resp, body = doReq(t, http.MethodPatch, ts.URL+"/api/v1/sessions/"+created.SessionID, map[string]any{"title": "nope"}, viewer)
+	if resp.StatusCode != http.StatusForbidden {
+		t.Fatalf("viewer rename status = %d, want 403 (body=%s)", resp.StatusCode, body)
+	}
+}
+
+// TestPersistUserMessageNamesSession exercises the Web persistence path end to end:
+// persistUserMessages (the orchestrator hook the HTTP/WS boundary calls) writes the
+// first user message through the real store, which names the session. A later user
+// message leaves the title alone.
+func TestPersistUserMessageNamesSession(t *testing.T) {
+	t.Parallel()
+	_, _, _, st := newHistoryEnv(t)
+	o := &Orchestrator{history: st, log: testLogger()}
+	ctx := context.Background()
+
+	// A sub session starts nameless; the first user message names it.
+	sub, err := st.NewSubSession(ctx, "owner")
+	if err != nil {
+		t.Fatalf("new sub: %v", err)
+	}
+	o.persistUserMessages(ctx, sub, []model.Message{model.TextMessage(model.RoleUser, "帮我规划一次旅行")}, "web:test", "chat")
+	o.persistUserMessages(ctx, sub, []model.Message{model.TextMessage(model.RoleUser, "第二句话")}, "web:test", "chat")
+
+	metas, err := st.ListSessions(ctx)
+	if err != nil {
+		t.Fatalf("list sessions: %v", err)
+	}
+	var gotSub string
+	for _, m := range metas {
+		if m.ID == sub {
+			gotSub = m.Title
+		}
+	}
+	if gotSub != "帮我规划一次旅行" {
+		t.Fatalf("sub title = %q, want 帮我规划一次旅行", gotSub)
+	}
+
+	// The main session is named from its first Web user message too.
+	o.persistUserMessages(ctx, history.MainSessionID, []model.Message{model.TextMessage(model.RoleUser, "  今天\n天气如何  ")}, "web:test", "chat")
+	metas, err = st.ListSessions(ctx)
+	if err != nil {
+		t.Fatalf("list sessions again: %v", err)
+	}
+	var gotMain string
+	for _, m := range metas {
+		if m.ID == history.MainSessionID {
+			gotMain = m.Title
+		}
+	}
+	if gotMain != "今天 天气如何" {
+		t.Fatalf("main title = %q, want 今天 天气如何", gotMain)
+	}
+}
+
 func TestHistoryNotWired(t *testing.T) {
 	t.Parallel()
 	_, ts, jwt := buildEnv(t, cfgDefault(), Deps{})
@@ -296,6 +445,7 @@ func TestHistoryNotWired(t *testing.T) {
 	}{
 		{http.MethodGet, "/api/v1/sessions/web/messages?limit=2", http.StatusNotImplemented},
 		{http.MethodPost, "/api/v1/sessions", http.StatusNotImplemented},
+		{http.MethodPatch, "/api/v1/sessions/web", http.StatusNotImplemented},
 	} {
 		resp, body := doReq(t, tc.method, ts.URL+tc.url, nil, tok)
 		if resp.StatusCode != tc.want {

internal/services/gateway/server.go

@@ -119,6 +119,9 @@ type HistoryStore interface {
 	ListAdapterLog(ctx context.Context, adapterID string, before int64, limit int) ([]history.Message, error)
 	ListAllLog(ctx context.Context, before int64, limit int) ([]history.Message, error)
 	DeleteSession(ctx context.Context, sessionID string) error
+	// RenameSession sets a session's display title (main or sub). An unknown id
+	// returns history.ErrSessionNotFound.
+	RenameSession(ctx context.Context, sessionID, title string) error
 	NewSubSession(ctx context.Context, ownerID string) (string, error)
 	ListSessions(ctx context.Context) ([]history.SessionMeta, error)
 }
@@ -400,6 +403,7 @@ func (s *Server) Handler() http.Handler {
 	mux.Handle("GET /api/v1/sessions/{id}/messages", historyAuth(http.HandlerFunc(s.handleListMessages)))
 	mux.Handle("POST /api/v1/sessions", historyAuth(http.HandlerFunc(s.handleCreateSubSession)))
 	mux.Handle("DELETE /api/v1/sessions/{id}", historyAuth(http.HandlerFunc(s.handleDeleteSession)))
+	mux.Handle("PATCH /api/v1/sessions/{id}", historyAuth(http.HandlerFunc(s.handleRenameSession)))
 
 	// Realtime.
 	mux.HandleFunc("/ws/chat", s.handleWS)

internal/services/gateway/session_orchestrator_test.go

@@ -199,6 +199,10 @@ func (f *fakeHistory) DeleteSession(context.Context, string) error {
 	return nil
 }
 
+func (f *fakeHistory) RenameSession(context.Context, string, string) error {
+	return nil
+}
+
 func (f *fakeHistory) NewSubSession(context.Context, string) (string, error) {
 	return "", nil
 }