internxt: persist rotated token returned by the user info call

The refresh endpoint returns a rotated token with a fresh expiry on
every successful call, but getUserInfo discarded it, so routine use
never extended the stored token's life. Once the stored token aged
out, accounts with 2FA enabled could not recover non-interactively
and required a manual reconnect.

Carry the rotated token out of getUserInfo and persist it in NewFs
via the same jwtToOAuth2Token + oauthutil.PutToken path that
refreshJWTToken uses, keeping f.cfg.Token in sync (same pattern as
refreshOrReLogin).

Fixes #9584

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/internxt/auth.go

@@ -28,6 +28,7 @@ type userInfo struct {
 	Bucket       string
 	BridgeUser   string
 	UserID       string
+	NewToken     string
 }
 
 type userInfoConfig struct {
@@ -61,6 +62,7 @@ func getUserInfo(ctx context.Context, cfg *userInfoConfig) (*userInfo, error) {
 		Bucket:       resp.User.Bucket,
 		BridgeUser:   resp.User.BridgeUser,
 		UserID:       resp.User.UserID,
+		NewToken:     resp.NewToken,
 	}
 
 	fs.Debugf(nil, "User info: rootFolderId=%s, bucket=%s",

backend/internxt/internxt.go

@@ -366,6 +366,25 @@ func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, e
 	f.bridgeUser = userInfo.BridgeUser
 	f.userID = userInfo.UserID
 
+	// The refresh endpoint rotates the token on every successful call.
+	// Persist the rotated token so routine use keeps the stored token
+	// current; otherwise it keeps its original expiry and accounts that
+	// cannot re-login non-interactively (2FA) eventually strand.
+	if userInfo.NewToken != "" {
+		if rotated, rotErr := jwtToOAuth2Token(userInfo.NewToken); rotErr != nil {
+			fs.Debugf(f, "Not adopting rotated token from user info: %v", rotErr)
+		} else {
+			// Use the rotated token for this session even if saving it
+			// fails; persistence is best-effort.
+			f.cfg.Token = userInfo.NewToken
+			if putErr := oauthutil.PutToken(name, m, rotated, false); putErr != nil {
+				fs.Debugf(f, "Failed to save rotated token from user info: %v", putErr)
+			} else {
+				fs.Debugf(f, "Persisted rotated token from user info, expiry: %v", rotated.Expiry)
+			}
+		}
+	}
+
 	f.features = (&fs.Features{
 		CanHaveEmptyDirectories: true,
 	}).Fill(ctx, f)