feat: add sync checkpoint restore for last successful sync

Capture rolling online DB snapshots after push/drain/reconcile and expose SyncPage 数据恢复 plus checkpoint/restore APIs; mark Z12h and restore done in coop docs.

Co-authored-by: Cursor <cursoragent@cursor.com>

platform/internal/handler/sync.go

@@ -262,6 +262,7 @@ func syncReconcileHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
 		_ = svcCtx.DBSync.Store().PatchStats(ch.ID, func(c *dbsync.Channel) {
 			c.LastReconcileAt = &now
 		})
+		dbsync.ScheduleCheckpoint(svcCtx.DBSync.Store(), ch, "reconcile")
 		httpx.OkJson(w, res)
 	}
 }
@@ -418,3 +419,62 @@ func syncDropTableHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
 		httpx.OkJson(w, res)
 	}
 }
+
+func syncCheckpointMetaHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if !requireDBSync(svcCtx, w) {
+			return
+		}
+		id := pathvar.Vars(r)["id"]
+		if _, err := svcCtx.DBSync.Store().GetChannelForTenant(id, syncTenantID(r)); err != nil {
+			authx.WriteError(w, http.StatusNotFound, err.Error())
+			return
+		}
+		meta, err := dbsync.LoadCheckpointMeta(svcCtx.DBSync.Store(), id)
+		if err != nil {
+			authx.WriteError(w, http.StatusBadRequest, err.Error())
+			return
+		}
+		httpx.OkJson(w, meta)
+	}
+}
+
+func syncRestoreHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if !requireDBSync(svcCtx, w) {
+			return
+		}
+		ch, err := svcCtx.DBSync.Store().GetChannelForTenant(pathvar.Vars(r)["id"], syncTenantID(r))
+		if err != nil {
+			authx.WriteError(w, http.StatusNotFound, err.Error())
+			return
+		}
+		var body struct {
+			Which   string `json:"which"`
+			Confirm bool   `json:"confirm"`
+		}
+		if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+			authx.WriteError(w, http.StatusBadRequest, err.Error())
+			return
+		}
+		if !body.Confirm {
+			authx.WriteError(w, http.StatusBadRequest, "请确认恢复：confirm=true")
+			return
+		}
+		which := strings.TrimSpace(body.Which)
+		if which == "" {
+			which = "latest"
+		}
+		res, err := dbsync.RestoreCheckpoint(r.Context(), svcCtx.DBSync.Store(), ch, which)
+		if err != nil {
+			authx.WriteError(w, http.StatusBadRequest, err.Error())
+			return
+		}
+		if svcCtx.Audit != nil {
+			_ = svcCtx.Audit.Log(r.Context(), syncTenantID(r), authx.UserID(r.Context()), "dbsync.restore", audit.DetailJSON(map[string]any{
+				"channel_id": ch.ID, "which": which, "synced_at": res.SyncedAt, "upserted": res.Upserted, "deleted": res.Deleted,
+			}))
+		}
+		httpx.OkJson(w, res)
+	}
+}