feat(user): server-synced open-with defaults + visible TOTP setup key

#5 — preferred_viewers map on user settings (ext → viewer id), patched via
/user/setting, exposed on the login User object and settings response.
openViewers consults the synced map before localStorage, so "always open
with" follows the user across devices; stale viewer ids fall back to the
local copy. Preference page lists saved ext → app pairs with per-entry
removal. Map is shape-validated and capped at 200 entries.

#3 — the 2FA setup dialog now shows the raw TOTP secret under the QR code
with click-to-copy, for authenticators that can't scan.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

frontend/public/locales/en-US/application.json

@@ -836,6 +836,9 @@
     "syncViewOff": "Do not sync",
     "folderClickAction": "Folder click action",
     "folderClickActionDes": "Choose what happens when you click a folder. \"Open\" navigates into the folder, \"Select\" selects it (double-click to open).",
+    "preferredViewers": "Default apps",
+    "preferredViewersDes": "Apps chosen with \"Always\" in the open-with dialog. They apply on all your devices; remove one to be asked again.",
+    "preferredViewersEmpty": "No default apps saved yet. Pick \"Always\" in the open-with dialog on a file.",
     "folderClickOpen": "Open",
     "folderClickSelect": "Select",
     "noAuthenticator": "Add a passkey to sign in using fingerprint, face or USB key.",
@@ -961,6 +964,8 @@
     "disable2FA": "Disable 2FA authentication",
     "2faDescription": "Please use any 2FA mobile app or password management software that supports 2FA to scan the QR code to add this site. After scanning, please fill in the 6-digit verification code given by the 2FA app to enable 2FA.",
     "inputCurrent2FACode": "Enter current 2FA verification code.",
+    "copySecret": "Can't scan? Click to copy the setup key",
+    "secretCopied": "Setup key copied",
     "timeZoneCode": "IANA timezone code",
     "authenticatorRemoved": "Authenticator removed.",
     "authenticatorAdded": "Authenticator added.",

frontend/public/locales/zh-CN/application.json

@@ -836,6 +836,9 @@
     "syncViewOff": "不同步",
     "folderClickAction": "文件夹点击操作",
     "folderClickActionDes": "选择点击文件夹时的行为。「打开」将进入文件夹，「选中」将选中文件夹（双击打开）。",
+    "preferredViewers": "默认打开方式",
+    "preferredViewersDes": "在「打开方式」对话框中选择「始终」后保存的应用，会在所有设备上生效。删除后下次打开时将重新询问。",
+    "preferredViewersEmpty": "尚未保存默认应用。在文件的「打开方式」对话框中选择「始终」即可添加。",
     "folderClickOpen": "打开",
     "folderClickSelect": "选中",
     "noAuthenticator": "添加通行密钥以使用人脸、指纹或 USB 密钥登录账号",
@@ -961,6 +964,8 @@
     "disable2FA": "关闭二步验证",
     "2faDescription": "请使用任意二步验证 APP 或者支持二步验证的密码管理软件扫描二维码添加本站。扫描完成后请填写二步验证 APP 给出的 6 位验证码以开启二步验证。",
     "inputCurrent2FACode": "输入当前二步验证 APP 给出的 6 位验证码：",
+    "copySecret": "无法扫码？点击复制密钥",
+    "secretCopied": "已复制密钥",
     "timeZoneCode": "IANA 时区名称标识",
     "authenticatorRemoved": "凭证已删除",
     "authenticatorAdded": "验证器已添加",

frontend/src/api/user.ts

@@ -27,6 +27,7 @@ export interface User {
   disable_view_sync?: boolean;
   share_links_in_profile?: ShareLinksInProfileLevel;
   share_default_private?: boolean;
+  preferred_viewers?: Record<string, string>;
 }
 export interface Group {
   id: string;
@@ -142,6 +143,7 @@ export interface UserSettings {
   disable_view_sync: boolean;
   share_links_in_profile: ShareLinksInProfileLevel;
   share_default_private?: boolean;
+  preferred_viewers?: Record<string, string>;
   oauth_grants?: OAuthGrant[];
 }
 
@@ -168,6 +170,7 @@ export interface PatchUserSetting {
   share_links_in_profile?: ShareLinksInProfileLevel;
   // Tri-state: "true" / "false" / "" (inherit the site default).
   share_default_private?: string;
+  preferred_viewers?: Record<string, string>;
 }
 
 export interface PasskeyCredentialOption {

frontend/src/component/FileManager/Dialogs/OpenWith.tsx

@@ -13,6 +13,7 @@ import {
 } from "@mui/material";
 import React, { useCallback, useEffect, useMemo, useState } from "react";
 import { useTranslation } from "react-i18next";
+import { sendUpdateUserSetting } from "../../../api/api.ts";
 import { Viewer, ViewerType } from "../../../api/explorer.ts";
 import { closeViewerSelector } from "../../../redux/globalStateSlice.ts";
 import { useAppDispatch, useAppSelector } from "../../../redux/hooks.ts";
@@ -129,7 +130,15 @@ const OpenWith = () => {
     }
 
     if (always) {
-      SessionManager.set(UserSettings.OpenWithPrefix + ext, viewer?.id ?? selectedViewer?.id);
+      const viewerId = viewer?.id ?? selectedViewer?.id;
+      SessionManager.set(UserSettings.OpenWithPrefix + ext, viewerId);
+      const user = SessionManager.currentUser();
+      if (user && viewerId) {
+        const merged = { ...(user.preferred_viewers ?? {}), [ext]: viewerId };
+        dispatch(sendUpdateUserSetting({ preferred_viewers: merged }))
+          .then(() => SessionManager.updateUserIfExist({ ...user, preferred_viewers: merged }))
+          .catch(() => {});
+      }
     }
 
     dispatch(

frontend/src/component/Pages/Setting/PreferenceSetting.tsx

@@ -23,6 +23,7 @@ import { UserSettings as UserSettingsType } from "../../../api/user.ts";
 import { languages } from "../../../i18n.ts";
 import { setPreferredTheme } from "../../../redux/globalStateSlice.ts";
 import { useAppDispatch, useAppSelector } from "../../../redux/hooks.ts";
+import { ViewersByID } from "../../../redux/siteConfigSlice.ts";
 import { clearLocalCustomView } from "../../../redux/thunks/filemanager.ts";
 import { selectLanguage } from "../../../redux/thunks/settings.ts";
 import SessionManager, { UserSettings } from "../../../session";
@@ -190,6 +191,27 @@ const PreferenceSetting = ({ setting, setSetting }: PreferenceSettingProps) => {
     }
   };
 
+  const preferredViewerEntries = useMemo(
+    () => Object.entries(setting.preferred_viewers ?? {}),
+    [setting.preferred_viewers],
+  );
+
+  const removePreferredViewer = (ext: string) => {
+    const next = { ...(setting.preferred_viewers ?? {}) };
+    delete next[ext];
+    setSetting({ ...setting, preferred_viewers: next });
+    setLoading(true);
+    dispatch(sendUpdateUserSetting({ preferred_viewers: next }))
+      .then(() => {
+        const session = SessionManager.currentLoginOrNull();
+        if (session?.user) {
+          SessionManager.updateUserIfExist({ ...session.user, preferred_viewers: next });
+        }
+        SessionManager.set(UserSettings.OpenWithPrefix + ext, undefined);
+      })
+      .finally(() => setLoading(false));
+  };
+
   return (
     <Stack spacing={3}>
       <SettingForm title={t("setting.language")} lgWidth={3}>
@@ -375,6 +397,25 @@ const PreferenceSetting = ({ setting, setSetting }: PreferenceSettingProps) => {
         </ToggleButtonGroup>
         <FormHelperText>{t("setting.folderClickActionDes")}</FormHelperText>
       </SettingForm>
+      <SettingForm title={t("setting.preferredViewers")} lgWidth={12}>
+        <Box>
+          {preferredViewerEntries.length == 0 && (
+            <FormHelperText>{t("setting.preferredViewersEmpty")}</FormHelperText>
+          )}
+          <Stack direction="row" spacing={1} sx={{ flexWrap: "wrap", gap: 1 }}>
+            {preferredViewerEntries.map(([ext, viewerId]) => (
+              <Chip
+                key={ext}
+                size="small"
+                label={`.${ext} → ${ViewersByID[viewerId] ? t(ViewersByID[viewerId].display_name) : viewerId}`}
+                onDelete={() => removePreferredViewer(ext)}
+                disabled={loading}
+              />
+            ))}
+          </Stack>
+          <FormHelperText>{t("setting.preferredViewersDes")}</FormHelperText>
+        </Box>
+      </SettingForm>
     </Stack>
   );
 };

frontend/src/component/Pages/Setting/Security/Enable2FADialog.tsx

@@ -3,13 +3,14 @@ import { useTranslation } from "react-i18next";
 import { useSnackbar } from "notistack";
 import { useAppDispatch, useAppSelector } from "../../../../redux/hooks.ts";
 import React, { useEffect, useState } from "react";
-import { Box, DialogContent, FormControl, Stack, styled, Typography, useMediaQuery, useTheme } from "@mui/material";
+import { Box, DialogContent, FormControl, Stack, styled, Tooltip, Typography, useMediaQuery, useTheme } from "@mui/material";
 import { CSSTransition, SwitchTransition } from "react-transition-group";
 import AutoHeight from "../../../Common/AutoHeight.tsx";
 import FacebookCircularProgress from "../../../Common/CircularProgress.tsx";
 import { get2FAInitSecret, sendUpdateUserSetting } from "../../../../api/api.ts";
 import { QRCodeSVG } from "qrcode.react";
 import SessionManager from "../../../../session";
+import { copyToClipboard } from "../../../../util";
 import { MuiOtpInput } from "mui-one-time-password-input";
 
 export interface Enable2FADialogProps {
@@ -129,6 +130,25 @@ const Enable2FADialog = ({ open, onClose, on2FAEnabled }: Enable2FADialogProps)
                       <Typography variant={"body2"} sx={{ mt: 1 }}>
                         {t("setting.2faDescription")}
                       </Typography>
+                      <Tooltip title={t("setting.copySecret")}>
+                        <Typography
+                          variant={"body2"}
+                          onClick={() => {
+                            copyToClipboard(secret);
+                            enqueueSnackbar({ message: t("setting.secretCopied"), variant: "success" });
+                          }}
+                          sx={{
+                            mt: 1,
+                            fontFamily: "monospace",
+                            letterSpacing: 1,
+                            cursor: "pointer",
+                            wordBreak: "break-all",
+                            userSelect: "all",
+                          }}
+                        >
+                          {secret}
+                        </Typography>
+                      </Tooltip>
                       <Typography variant={"body2"} sx={{ mt: 1 }}>
                         {t("setting.inputCurrent2FACode")}
                       </Typography>

frontend/src/redux/thunks/viewer.ts

@@ -74,12 +74,18 @@ export function openViewers(
     const ext = fileExtension(file.name) ?? "";
     const entitySize = size ?? file.size;
 
-    // Try user preference
+    // Try user preference — the server-synced map wins over the per-device
-    const userPreference = SessionManager.get(UserSettings.OpenWithPrefix + ext);
+    // localStorage copy so the choice follows the user across devices. A
-    if (!ignorePreference && userPreference && ViewersByID[userPreference]) {
+    // stale server entry (viewer removed site-wide) falls back to local.
+    if (!ignorePreference) {
+      const serverPreference = SessionManager.currentUser()?.preferred_viewers?.[ext];
+      const localPreference = SessionManager.get(UserSettings.OpenWithPrefix + ext);
+      const userPreference = [serverPreference, localPreference].find((id) => id && ViewersByID[id]);
+      if (userPreference) {
         dispatch(openViewer(file, ViewersByID[userPreference], entitySize, preferredVersion));
         return;
       }
+    }
 
     const viewerOptions = Viewers[ext];
 

inventory/types/types.go

@@ -20,6 +20,10 @@ type (
 		// ShareDefaultPrivate overrides the site-wide private-share default
 		// for this user. nil means inherit the site default.
 		ShareDefaultPrivate *bool `json:"share_default_private,omitempty"`
+		// PreferredViewers maps file extensions (without dot, lowercase) to
+		// viewer IDs chosen via "always open with". Synced server-side so the
+		// preference follows the user across devices.
+		PreferredViewers map[string]string `json:"preferred_viewers,omitempty"`
 	}
 
 	ShareLinksInProfileLevel string

service/user/response.go

@@ -33,6 +33,7 @@ type UserSettings struct {
 	DisableViewSync         bool              `json:"disable_view_sync"`
 	ShareLinksInProfile     string            `json:"share_links_in_profile"`
 	ShareDefaultPrivate     *bool             `json:"share_default_private,omitempty"`
+	PreferredViewers        map[string]string `json:"preferred_viewers,omitempty"`
 	OAuthGrants             []OauthGrant      `json:"oauth_grants,omitempty"`
 }
 
@@ -49,6 +50,7 @@ func BuildUserSettings(u *ent.User, passkeys []*ent.Passkey, parser *uaparser.Pa
 		DisableViewSync:     u.Settings.DisableViewSync,
 		ShareLinksInProfile: string(u.Settings.ShareLinksInProfile),
 		ShareDefaultPrivate: u.Settings.ShareDefaultPrivate,
+		PreferredViewers:    u.Settings.PreferredViewers,
 		OAuthGrants: lo.Map(grants, func(item *ent.OAuthGrant, index int) OauthGrant {
 			return BuildOauthGrant(item)
 		}),
@@ -124,6 +126,8 @@ type User struct {
 	// the site default applies. Never resolved here — the dialog computes the
 	// effective default from user ?? site.
 	ShareDefaultPrivate *bool `json:"share_default_private,omitempty"`
+	// PreferredViewers maps file extensions to viewer IDs ("always open with").
+	PreferredViewers map[string]string `json:"preferred_viewers,omitempty"`
 }
 
 type Group struct {
@@ -182,6 +186,7 @@ func BuildUser(user *ent.User, idEncoder hashid.Encoder) User {
 		DisableViewSync:     user.Settings.DisableViewSync,
 		ShareLinksInProfile: user.Settings.ShareLinksInProfile,
 		ShareDefaultPrivate: user.Settings.ShareDefaultPrivate,
+		PreferredViewers:    user.Settings.PreferredViewers,
 	}
 }
 

service/user/setting.go

@@ -9,6 +9,7 @@ import (
 	"net/url"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
 
 	"github.com/cloudreve/Cloudreve/v4/application/dependency"
@@ -233,10 +234,33 @@ type (
 		// ShareDefaultPrivate accepts "true", "false" or "" (clear the
 		// override and inherit the site default).
 		ShareDefaultPrivate *string `json:"share_default_private" binding:"omitempty"`
+		// PreferredViewers replaces the whole extension → viewer-id map.
+		PreferredViewers *map[string]string `json:"preferred_viewers" binding:"omitempty"`
 	}
 	PatchUserSettingParamsCtx struct{}
 )
 
+var (
+	preferredViewerExtPattern = regexp.MustCompile(`^[a-z0-9]{1,20}$`)
+	preferredViewerIDPattern  = regexp.MustCompile(`^[\w.\-:]{1,64}$`)
+)
+
+const preferredViewersMaxEntries = 200
+
+// validatePreferredViewers bounds the extension → viewer-id map to sane
+// shapes so it can't be abused as arbitrary JSON storage.
+func validatePreferredViewers(m map[string]string) error {
+	if len(m) > preferredViewersMaxEntries {
+		return serializer.NewError(serializer.CodeParamErr, "Too many preferred viewers", nil)
+	}
+	for ext, viewerID := range m {
+		if !preferredViewerExtPattern.MatchString(ext) || !preferredViewerIDPattern.MatchString(viewerID) {
+			return serializer.NewError(serializer.CodeParamErr, "Invalid preferred viewer entry", nil)
+		}
+	}
+	return nil
+}
+
 func (s *PatchUserSetting) Patch(c *gin.Context) error {
 	dep := dependency.FromContext(c)
 	u := inventory.UserFromContext(c)
@@ -302,6 +326,14 @@ func (s *PatchUserSetting) Patch(c *gin.Context) error {
 		saveSetting = true
 	}
 
+	if s.PreferredViewers != nil {
+		if err := validatePreferredViewers(*s.PreferredViewers); err != nil {
+			return err
+		}
+		u.Settings.PreferredViewers = *s.PreferredViewers
+		saveSetting = true
+	}
+
 	if s.CurrentPassword != nil && s.NewPassword != nil {
 		if err := auth.CheckScope(c, types.ScopeUserSecurityInfoWrite); err != nil {
 			return err

service/user/setting_test.go

@@ -3,6 +3,7 @@ package user
 import (
 	"context"
 	"net/http/httptest"
+	"strconv"
 	"testing"
 
 	"github.com/cloudreve/Cloudreve/v4/application/dependency"
@@ -81,3 +82,65 @@ func TestPatchUserSettingShareDefaults(t *testing.T) {
 	// Invalid profile visibility rejected.
 	require.Error(t, patch(&PatchUserSetting{ShareLinksInProfile: strPtr("friends_only")}))
 }
+
+// TestPatchUserSettingPreferredViewers verifies the extension → viewer-id map
+// is persisted and validated (upstream: persist "always open with" in DB).
+func TestPatchUserSettingPreferredViewers(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	client := enttest.Open(t, "sqlite3", "file:"+t.Name()+"?mode=memory&cache=shared")
+	t.Cleanup(func() { require.NoError(t, client.Close()) })
+	ctx := context.Background()
+
+	group := client.Group.Create().SetName("g").SetPermissions(&boolset.BooleanSet{}).SaveX(ctx)
+	u := client.User.Create().
+		SetEmail("viewers@example.com").
+		SetNick("viewers").
+		SetStatus("active").
+		SetGroup(group).
+		SetSettings(&types.UserSetting{}).
+		SaveX(ctx)
+
+	newCtx := func() *gin.Context {
+		engine := gin.New()
+		engine.ContextWithFallback = true
+		c := gin.CreateTestContextOnly(httptest.NewRecorder(), engine)
+		c.Request = httptest.NewRequest("PATCH", "/", nil)
+		util.WithValue(c, dependency.DepCtx{}, dependency.NewDependency(
+			dependency.WithUserClient(inventory.NewUserClient(client)),
+		))
+		util.WithValue(c, inventory.UserCtx{}, u)
+		return c
+	}
+
+	patch := func(s *PatchUserSetting) error {
+		return s.Patch(newCtx())
+	}
+
+	// Valid map persists.
+	valid := map[string]string{"md": "codemirror", "epub": "epub"}
+	require.NoError(t, patch(&PatchUserSetting{PreferredViewers: &valid}))
+	require.Equal(t, "codemirror", u.Settings.PreferredViewers["md"])
+
+	persisted := client.User.GetX(ctx, u.ID)
+	require.Equal(t, "epub", persisted.Settings.PreferredViewers["epub"])
+
+	// Empty map clears all preferences.
+	empty := map[string]string{}
+	require.NoError(t, patch(&PatchUserSetting{PreferredViewers: &empty}))
+	require.Empty(t, u.Settings.PreferredViewers)
+
+	// Invalid extension key rejected.
+	badExt := map[string]string{"../evil": "x"}
+	require.Error(t, patch(&PatchUserSetting{PreferredViewers: &badExt}))
+
+	// Invalid viewer id rejected.
+	badID := map[string]string{"md": "../../etc"}
+	require.Error(t, patch(&PatchUserSetting{PreferredViewers: &badID}))
+
+	// Oversized map rejected.
+	big := map[string]string{}
+	for i := 0; i < preferredViewersMaxEntries+1; i++ {
+		big[string(rune('a'+i%26))+strconv.Itoa(i)] = "v"
+	}
+	require.Error(t, patch(&PatchUserSetting{PreferredViewers: &big}))
+}