diff --git a/internal/auth/token_store.go b/internal/auth/token_store.go
index bbf4b98758..0a99e04375 100644
--- a/internal/auth/token_store.go
+++ b/internal/auth/token_store.go
@@ -40,15 +40,23 @@ func MaskToken(token string) string {
 
 // GetStoredToken reads the stored UAT for a given (appId, userOpenId) pair.
 func GetStoredToken(appId, userOpenId string) *StoredUAToken {
+	token, _ := readStoredToken(appId, userOpenId)
+	return token
+}
+
+func readStoredToken(appId, userOpenId string) (*StoredUAToken, error) {
 	jsonStr, err := keychain.Get(keychain.LarkCliService, accountKey(appId, userOpenId))
-	if err != nil || jsonStr == "" {
-		return nil
+	if err != nil {
+		return nil, err
+	}
+	if jsonStr == "" {
+		return nil, nil
 	}
 	var token StoredUAToken
 	if err := json.Unmarshal([]byte(jsonStr), &token); err != nil {
-		return nil
+		return nil, err
 	}
-	return &token
+	return &token, nil
 }
 
 // SetStoredToken persists a UAT.
@@ -66,6 +74,54 @@ func RemoveStoredToken(appId, userOpenId string) error {
 	return keychain.Remove(keychain.LarkCliService, accountKey(appId, userOpenId))
 }
 
+// isSameStoredTokenGeneration reports whether two snapshots represent the same
+// refresh-token generation. Access tokens are used only for case that does not
+// contain a refresh token.
+func isSameStoredTokenGeneration(current, expected *StoredUAToken) bool {
+	if current == nil || expected == nil ||
+		current.AppId != expected.AppId ||
+		current.UserOpenId != expected.UserOpenId {
+		return false
+	}
+	if current.RefreshToken != "" || expected.RefreshToken != "" {
+		return current.RefreshToken == expected.RefreshToken
+	}
+	return current.AccessToken == expected.AccessToken
+}
+
+// setStoredTokenIfCurrent stores updated only when expected is still the
+// current token generation. It returns the token present after the check and
+// whether the update was applied.
+func setStoredTokenIfCurrent(expected, updated *StoredUAToken) (*StoredUAToken, bool, error) {
+	current, err := readStoredToken(expected.AppId, expected.UserOpenId)
+	if err != nil {
+		return nil, false, err
+	}
+	if !isSameStoredTokenGeneration(current, expected) {
+		return current, false, nil
+	}
+	if err := SetStoredToken(updated); err != nil {
+		return current, false, err
+	}
+	return updated, true, nil
+}
+
+// removeStoredTokenIfCurrent removes expected only when it is still the
+// current token generation. It returns the token retained on a mismatch.
+func removeStoredTokenIfCurrent(expected *StoredUAToken) (*StoredUAToken, bool, error) {
+	current, err := readStoredToken(expected.AppId, expected.UserOpenId)
+	if err != nil {
+		return nil, false, err
+	}
+	if !isSameStoredTokenGeneration(current, expected) {
+		return current, false, nil
+	}
+	if err := RemoveStoredToken(expected.AppId, expected.UserOpenId); err != nil {
+		return current, false, err
+	}
+	return nil, true, nil
+}
+
 // TokenStatus determines the freshness of a stored token.
 func TokenStatus(token *StoredUAToken) string {
 	now := time.Now().UnixMilli()
diff --git a/internal/auth/uat_client.go b/internal/auth/uat_client.go
index d1a0683927..06202388c0 100644
--- a/internal/auth/uat_client.go
+++ b/internal/auth/uat_client.go
@@ -4,17 +4,19 @@
 package auth
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
-	"net/url"
+	"net/http/httptrace"
 	"os"
 	"path/filepath"
 	"regexp"
-	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/gofrs/flock"
@@ -81,7 +83,7 @@ func GetValidAccessToken(httpClient *http.Client, opts UATCallOptions) (string,
 	}
 
 	if status == "needs_refresh" {
-		refreshed, err := refreshWithLock(httpClient, opts, stored)
+		refreshed, err := refreshWithLock(httpClient, opts)
 		if err != nil {
 			return "", err
 		}
@@ -103,7 +105,7 @@ func GetValidAccessToken(httpClient *http.Client, opts UATCallOptions) (string,
 }
 
 // refreshWithLock acquires a file lock before attempting to refresh the token.
-func refreshWithLock(httpClient *http.Client, opts UATCallOptions, stored *StoredUAToken) (*StoredUAToken, error) {
+func refreshWithLock(httpClient *http.Client, opts UATCallOptions) (*StoredUAToken, error) {
 	key := fmt.Sprintf("%s:%s", opts.AppId, opts.UserOpenId)
 
 	// 1. Process-level lock (prevents multiple goroutines in the same process)
@@ -125,12 +127,9 @@ func refreshWithLock(httpClient *http.Client, opts UATCallOptions, stored *Store
 		refreshLocks.Delete(key)
 	}()
 
-	// 2. Cross-process lock using flock
-	// We use the same underlying storage directory resolution as keychain_other.go
-	// to ensure locks are isolated properly alongside other sensitive data.
-	configDir := core.GetConfigDir()
-
-	lockDir := filepath.Join(configDir, "locks")
+	// 2. Cross-process lock using the global config directory so all
+	// workspaces sharing the same token also share the same lock.
+	lockDir := filepath.Join(core.GetBaseConfigDir(), "locks")
 	if err := vfs.MkdirAll(lockDir, 0700); err != nil {
 		return nil, fmt.Errorf("failed to create lock directory: %w", err)
 	}
@@ -153,21 +152,100 @@ func refreshWithLock(httpClient *http.Client, opts UATCallOptions, stored *Store
 	}
 	defer fileLock.Unlock()
 
-	// 3. Double-checked locking: Check if another process has already refreshed the token
-	freshStored := GetStoredToken(opts.AppId, opts.UserOpenId)
-	if freshStored != nil {
-		status := TokenStatus(freshStored)
-		if status == "valid" {
-			// Another process refreshed it, we can just use the new token
-			if opts.ErrOut != nil {
-				fmt.Fprintf(opts.ErrOut, "[lark-cli] uat-client: token already refreshed by another process\n")
-			}
-			return freshStored, nil
+	// 3. Re-read under the global lock and use only the current generation.
+	freshStored, err := readStoredToken(opts.AppId, opts.UserOpenId)
+	if err != nil {
+		return nil, err
+	}
+	if freshStored == nil {
+		return nil, nil
+	}
+
+	switch TokenStatus(freshStored) {
+	case "valid":
+		if opts.ErrOut != nil {
+			fmt.Fprintf(opts.ErrOut, "[lark-cli] uat-client: token already refreshed by another process\n")
+		}
+		return freshStored, nil
+	case "expired":
+		retained, removed, err := removeStoredTokenIfCurrent(freshStored)
+		if err != nil {
+			return nil, err
+		}
+		if !removed {
+			return storedTokenAfterGenerationChange(retained, opts.UserOpenId)
+		}
+		if opts.ErrOut != nil {
+			fmt.Fprintf(opts.ErrOut, "[lark-cli] uat-client: refresh_token expired for %s, clearing\n", opts.UserOpenId)
 		}
+		return nil, nil
+	}
+
+	if err := ensureDirWritable(lockDir, "tmp_writetest-*"); err != nil {
+		if opts.ErrOut != nil {
+			fmt.Fprintf(opts.ErrOut,
+				"[lark-cli] [WARN] uat-client: refresh lock directory is not writable while refreshing: %v\n",
+				err)
+		}
+		return nil, err
+	}
+
+	if err := ensureTokenStorageWritable(opts.AppId, opts.UserOpenId); err != nil {
+		if opts.ErrOut != nil {
+			fmt.Fprintf(opts.ErrOut,
+				"[lark-cli] [WARN] uat-client: token storage is not writable while refreshing: %v\n",
+				err)
+		}
+		return nil, err
 	}
 
 	// 4. Actually perform the refresh
-	return doRefreshToken(httpClient, opts, stored)
+	return doRefreshToken(httpClient, opts, freshStored)
+}
+
+const refreshMaxAttempts = 2
+
+type refreshRequest struct {
+	GrantType    string `json:"grant_type"`
+	RefreshToken string `json:"refresh_token"`
+	ClientID     string `json:"client_id"`
+	ClientSecret string `json:"client_secret"`
+}
+
+// refreshResponse contains only fields documented by the OAuth token endpoint.
+// Pointers distinguish an omitted numeric field from a real zero value.
+type refreshResponse struct {
+	Code                  *int   `json:"code"`
+	AccessToken           string `json:"access_token"`
+	ExpiresIn             *int64 `json:"expires_in"`
+	RefreshToken          string `json:"refresh_token"`
+	RefreshTokenExpiresIn *int64 `json:"refresh_token_expires_in"`
+	TokenType             string `json:"token_type"`
+	Scope                 string `json:"scope"`
+	Error                 string `json:"error"`
+	ErrorDescription      string `json:"error_description"`
+}
+
+// refreshAction describes both retry behavior and local token disposition.
+type refreshAction uint8
+
+const (
+	// refreshSaveResponse saves a successful response.
+	refreshSaveResponse refreshAction = iota
+	// refreshRetryAndPreserve retries, preserving the stored token if retry fails.
+	refreshRetryAndPreserve
+	// refreshRetryAndClear retries, clearing the stored token if retry fails.
+	refreshRetryAndClear
+	// refreshStopAndPreserve stops without clearing the stored token.
+	refreshStopAndPreserve
+	// refreshStopAndClear stops and clears the stored token.
+	refreshStopAndClear
+)
+
+type refreshResult struct {
+	action   refreshAction
+	response refreshResponse
+	err      error
 }
 
 // doRefreshToken performs the actual HTTP request to refresh the token.
@@ -177,124 +255,252 @@ func doRefreshToken(httpClient *http.Client, opts UATCallOptions, stored *Stored
 		errOut = os.Stderr
 	}
 
-	now := time.Now().UnixMilli()
-	if now >= stored.RefreshExpiresAt {
+	if time.Now().UnixMilli() >= stored.RefreshExpiresAt {
 		fmt.Fprintf(errOut, "[lark-cli] uat-client: refresh_token expired for %s, clearing\n", opts.UserOpenId)
-		if err := RemoveStoredToken(opts.AppId, opts.UserOpenId); err != nil {
+		retained, removed, err := removeStoredTokenIfCurrent(stored)
+		if err != nil {
 			fmt.Fprintf(errOut, "[lark-cli] [WARN] uat-client: failed to remove expired token: %v\n", err)
+			return nil, err
+		}
+		if !removed {
+			return storedTokenAfterGenerationChange(retained, opts.UserOpenId)
 		}
 		return nil, nil
 	}
 
-	endpoints := ResolveOAuthEndpoints(opts.Domain)
+	endpoint := ResolveOAuthEndpoints(opts.Domain).Token
+	uncertain := false
+	for attempt := 1; attempt <= refreshMaxAttempts; attempt++ {
+		result := refreshOnce(httpClient, endpoint, opts, stored)
+		if result.action == refreshSaveResponse {
+			return saveRefreshResponse(opts, stored, result.response)
+		}
 
-	callEndpoint := func() (map[string]interface{}, error) {
-		form := url.Values{}
-		form.Set("grant_type", "refresh_token")
-		form.Set("refresh_token", stored.RefreshToken)
-		form.Set("client_id", opts.AppId)
-		form.Set("client_secret", opts.AppSecret)
+		switch result.action {
+		case refreshRetryAndPreserve, refreshRetryAndClear:
+			if result.action == refreshRetryAndClear {
+				uncertain = true
+			}
+			if attempt < refreshMaxAttempts {
+				fmt.Fprintf(errOut,
+					"[lark-cli] [WARN] uat-client: refresh attempt %d/%d failed for %s: %v; retrying\n",
+					attempt, refreshMaxAttempts, opts.UserOpenId, result.err)
+				continue
+			}
+		case refreshStopAndPreserve, refreshStopAndClear:
+		default:
+			return nil, errs.NewInternalError(errs.SubtypeUnknown,
+				"unrecognized token refresh action %d", result.action)
+		}
 
-		req, err := http.NewRequest("POST", endpoints.Token, strings.NewReader(form.Encode()))
-		if err != nil {
-			return nil, err
+		clearToken := result.action == refreshStopAndClear ||
+			result.action == refreshRetryAndClear ||
+			(result.action == refreshRetryAndPreserve && uncertain)
+		if !clearToken {
+			fmt.Fprintf(errOut,
+				"[lark-cli] [WARN] uat-client: refresh failed for %s, preserving token: %v\n",
+				opts.UserOpenId, result.err)
+			return nil, result.err
 		}
-		req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
 
-		resp, err := httpClient.Do(req)
+		if problem, ok := errs.ProblemOf(result.err); ok {
+			problem.Retryable = false
+		}
+		retained, removed, err := removeStoredTokenIfCurrent(stored)
 		if err != nil {
+			fmt.Fprintf(errOut, "[lark-cli] [WARN] uat-client: failed to remove token: %v\n", err)
 			return nil, err
 		}
-		defer resp.Body.Close()
-		logHTTPResponse(resp)
+		if !removed {
+			fmt.Fprintf(errOut,
+				"[lark-cli] [WARN] uat-client: stored token changed during refresh for %s, preserving current token\n",
+				opts.UserOpenId)
+			return storedTokenAfterGenerationChange(retained, opts.UserOpenId)
+		}
+		fmt.Fprintf(errOut,
+			"[lark-cli] [WARN] uat-client: refresh failed for %s, token cleared: %v\n",
+			opts.UserOpenId, result.err)
+		return nil, result.err
+	}
 
-		body, err := io.ReadAll(resp.Body)
-		if err != nil {
-			return nil, fmt.Errorf("token refresh read error: %v", err)
+	return nil, errs.NewInternalError(errs.SubtypeUnknown,
+		"token refresh exhausted attempts without a result")
+}
+
+func refreshOnce(httpClient *http.Client, endpoint string, opts UATCallOptions, stored *StoredUAToken) refreshResult {
+	payload, err := json.Marshal(refreshRequest{
+		GrantType:    "refresh_token",
+		RefreshToken: stored.RefreshToken,
+		ClientID:     opts.AppId,
+		ClientSecret: opts.AppSecret,
+	})
+	if err != nil {
+		return refreshResult{
+			action: refreshStopAndPreserve,
+			err: errs.NewInternalError(errs.SubtypeSDKError,
+				"failed to encode token refresh request: %v", err).
+				WithCause(err),
 		}
-		var data map[string]interface{}
-		if err := json.Unmarshal(body, &data); err != nil {
-			return nil, fmt.Errorf("token refresh parse error: %w", err)
+	}
+
+	var wroteRequest atomic.Bool
+	trace := &httptrace.ClientTrace{
+		WroteRequest: func(httptrace.WroteRequestInfo) {
+			wroteRequest.Store(true)
+		},
+	}
+	ctx := httptrace.WithClientTrace(context.Background(), trace)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint, bytes.NewReader(payload))
+	if err != nil {
+		return refreshResult{
+			action: refreshStopAndPreserve,
+			err: errs.NewInternalError(errs.SubtypeSDKError,
+				"failed to create token refresh request: %v", err).
+				WithCause(err),
 		}
-		return data, nil
 	}
+	req.Header.Set("Content-Type", "application/json; charset=utf-8")
 
-	data, err := callEndpoint()
+	resp, err := httpClient.Do(req)
 	if err != nil {
-		return nil, err
+		action := refreshRetryAndPreserve
+		if wroteRequest.Load() {
+			action = refreshRetryAndClear
+		}
+		if _, ok := errs.ProblemOf(err); !ok {
+			err = errs.NewNetworkError(errs.SubtypeNetworkTransport,
+				"token refresh request failed: %v", err).
+				WithRetryable().
+				WithCause(err)
+		}
+		return refreshResult{
+			action: action,
+			err:    err,
+		}
 	}
+	defer resp.Body.Close()
+	logHTTPResponse(resp)
 
-	code := getInt(data, "code", -1)
-	meta, metaOK := errclass.LookupCodeMeta(code)
-	if metaOK && meta.Category == errs.CategoryPolicy {
-		challengeUrl := getStr(data, "challenge_url")
-		cliHint := getStr(data, "cli_hint")
-		msg := getStr(data, "error_description")
-
-		return nil, &errs.SecurityPolicyError{
-			Problem: errs.Problem{
-				Category: errs.CategoryPolicy,
-				Subtype:  meta.Subtype,
-				Code:     code,
-				Message:  msg,
-				Hint:     cliHint,
-			},
-			ChallengeURL: challengeUrl,
-		}
-	}
-
-	errStr := getStr(data, "error")
-
-	if (code != -1 && code != 0) || errStr != "" {
-		// Retryable server error: retry once, then clear token on second failure.
-		if metaOK && meta.Category == errs.CategoryAuthentication && meta.Retryable {
-			fmt.Fprintf(errOut, "[lark-cli] [WARN] uat-client: refresh transient error (code=%d) for %s, retrying once\n", code, opts.UserOpenId)
-			data, err = callEndpoint()
-			if err != nil {
-				fmt.Fprintf(errOut, "[lark-cli] [WARN] uat-client: refresh retry network error for %s, clearing token\n", opts.UserOpenId)
-				if err := RemoveStoredToken(opts.AppId, opts.UserOpenId); err != nil {
-					fmt.Fprintf(errOut, "[lark-cli] [WARN] uat-client: failed to remove token: %v\n", err)
-				}
-				return nil, nil
-			}
-			code = getInt(data, "code", -1)
-			errStr = getStr(data, "error")
-			if (code != -1 && code != 0) || errStr != "" {
-				fmt.Fprintf(errOut, "[lark-cli] [WARN] uat-client: refresh failed after retry (code=%d) for %s, clearing token\n", code, opts.UserOpenId)
-				if err := RemoveStoredToken(opts.AppId, opts.UserOpenId); err != nil {
-					fmt.Fprintf(errOut, "[lark-cli] [WARN] uat-client: failed to remove token: %v\n", err)
-				}
-				return nil, nil
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return refreshResult{
+			action: refreshRetryAndClear,
+			err: errs.NewNetworkError(errs.SubtypeNetworkTransport,
+				"token refresh response read failed: %v", err).
+				WithRetryable().
+				WithCause(err),
+		}
+	}
+
+	var parsed refreshResponse
+	if err := json.Unmarshal(body, &parsed); err != nil {
+		return refreshResult{
+			action: refreshRetryAndClear,
+			err: errs.NewInternalError(errs.SubtypeInvalidResponse,
+				"token refresh returned invalid JSON: %v", err).
+				WithRetryable().
+				WithCause(err),
+		}
+	}
+	if parsed.Code == nil {
+		return refreshResult{
+			action: refreshRetryAndClear,
+			err: errs.NewInternalError(errs.SubtypeInvalidResponse,
+				"token refresh response is missing required field code").
+				WithRetryable(),
+		}
+	}
+
+	code := *parsed.Code
+	if code != 0 {
+		if meta, ok := errclass.LookupCodeMeta(code); ok && meta.Category == errs.CategoryPolicy {
+			var policyFields struct {
+				ChallengeURL string `json:"challenge_url"`
+				CLIHint      string `json:"cli_hint"`
 			}
-			// Retry succeeded, fall through to parse token below.
-		} else {
-			// All other errors: clear token, require re-authorization.
-			fmt.Fprintf(errOut, "[lark-cli] [WARN] uat-client: refresh failed (code=%d), clearing token for %s\n", code, opts.UserOpenId)
-			if err := RemoveStoredToken(opts.AppId, opts.UserOpenId); err != nil {
-				fmt.Fprintf(errOut, "[lark-cli] [WARN] uat-client: failed to remove token: %v\n", err)
+			_ = json.Unmarshal(body, &policyFields)
+			return refreshResult{
+				action: refreshStopAndPreserve,
+				err: &errs.SecurityPolicyError{
+					Problem: errs.Problem{
+						Category: errs.CategoryPolicy,
+						Subtype:  meta.Subtype,
+						Code:     code,
+						Message:  parsed.ErrorDescription,
+						Hint:     policyFields.CLIHint,
+					},
+					ChallengeURL: policyFields.ChallengeURL,
+				},
 			}
-			return nil, nil
 		}
+
+		message := parsed.ErrorDescription
+		if message == "" {
+			message = parsed.Error
+		}
+		// BuildAPIError accepts the common OpenAPI message key; OAuth names
+		// the same value error_description.
+		apiErr := errclass.BuildAPIError(map[string]any{
+			"code": code,
+			"msg":  message,
+		}, errclass.ClassifyContext{
+			Brand:    string(opts.Domain),
+			AppID:    opts.AppId,
+			Identity: "user",
+		})
+		var authErr *errs.AuthenticationError
+		if errors.As(apiErr, &authErr) {
+			authErr.UserOpenID = opts.UserOpenId
+		}
+		return refreshResult{action: refreshActionForCode(code), err: apiErr}
+	}
+
+	if parsed.RefreshToken == "" {
+		parsed.RefreshToken = stored.RefreshToken
 	}
 
-	accessToken := getStr(data, "access_token")
-	if accessToken == "" {
-		return nil, fmt.Errorf("Token refresh returned no access_token")
+	if parsed.AccessToken == "" {
+		return refreshResult{
+			action: refreshStopAndPreserve,
+			err: errs.NewInternalError(errs.SubtypeInvalidResponse,
+				"token refresh response is missing required field access_token").
+				WithRetryable(),
+		}
 	}
 
-	refreshToken := getStr(data, "refresh_token")
-	if refreshToken == "" {
-		refreshToken = stored.RefreshToken
+	if parsed.ExpiresIn == nil || *parsed.ExpiresIn <= 0 {
+		parsed.ExpiresIn = new(int64)
+		*parsed.ExpiresIn = 7200 // 2 hours
+	}
+
+	if parsed.RefreshTokenExpiresIn == nil || *parsed.RefreshTokenExpiresIn <= 0 {
+		parsed.RefreshTokenExpiresIn = new(int64)
+		if stored.RefreshExpiresAt <= 0 {
+			*parsed.RefreshTokenExpiresIn = 2592000 // 30 days
+		} else {
+			now := time.Now().UnixMilli()
+			*parsed.RefreshTokenExpiresIn = (stored.RefreshExpiresAt - now) / 1000
+		}
 	}
 
-	expiresIn := getInt(data, "expires_in", 7200)
-	refreshExpiresIn := getInt(data, "refresh_token_expires_in", 0)
-	refreshExpiresAt := stored.RefreshExpiresAt
-	if refreshExpiresIn > 0 {
-		refreshExpiresAt = now + int64(refreshExpiresIn)*1000
+	return refreshResult{action: refreshSaveResponse, response: parsed}
+}
+
+func refreshActionForCode(code int) refreshAction {
+	meta, ok := errclass.LookupCodeMeta(code)
+	switch {
+	case ok && meta.Category == errs.CategoryPolicy:
+		return refreshStopAndPreserve
+	case ok && meta.Retryable:
+		return refreshRetryAndPreserve
+	default:
+		return refreshStopAndClear
 	}
+}
 
-	scope := getStr(data, "scope")
+func saveRefreshResponse(opts UATCallOptions, stored *StoredUAToken, response refreshResponse) (*StoredUAToken, error) {
+	now := time.Now().UnixMilli()
+	scope := response.Scope
 	if scope == "" {
 		scope = stored.Scope
 	}
@@ -302,16 +508,102 @@ func doRefreshToken(httpClient *http.Client, opts UATCallOptions, stored *Stored
 	updated := &StoredUAToken{
 		UserOpenId:       stored.UserOpenId,
 		AppId:            opts.AppId,
-		AccessToken:      accessToken,
-		RefreshToken:     refreshToken,
-		ExpiresAt:        now + int64(expiresIn)*1000,
-		RefreshExpiresAt: refreshExpiresAt,
+		AccessToken:      response.AccessToken,
+		RefreshToken:     response.RefreshToken,
+		ExpiresAt:        now + *response.ExpiresIn*1000,
+		RefreshExpiresAt: now + *response.RefreshTokenExpiresIn*1000,
 		Scope:            scope,
 		GrantedAt:        stored.GrantedAt,
 	}
-
-	if err := SetStoredToken(updated); err != nil {
+	current, saved, err := setStoredTokenIfCurrent(stored, updated)
+	if err != nil {
 		return nil, err
 	}
+	if !saved {
+		if opts.ErrOut != nil {
+			fmt.Fprintf(opts.ErrOut,
+				"[lark-cli] [WARN] uat-client: stored token changed during refresh for %s, preserving current token\n",
+				opts.UserOpenId)
+		}
+		return storedTokenAfterGenerationChange(current, opts.UserOpenId)
+	}
 	return updated, nil
 }
+
+func storedTokenAfterGenerationChange(current *StoredUAToken, userOpenId string) (*StoredUAToken, error) {
+	if current == nil {
+		return nil, nil
+	}
+	if TokenStatus(current) == "valid" {
+		return current, nil
+	}
+	return nil, errs.NewInternalError(errs.SubtypeStorage,
+		"stored refresh token changed while refreshing user %q", userOpenId).
+		WithRetryable().
+		WithHint("retry the command")
+}
+
+func ensureDirWritable(dir, tempPrefix string) error {
+	if dir == "" {
+		return nil
+	}
+
+	if err := vfs.MkdirAll(dir, 0700); err != nil {
+		return errs.NewInternalError(errs.SubtypeFileIO,
+			"failed to access refresh lock directory %q", dir).
+			WithCause(err).
+			WithHint("If running in a sandbox or read-only workspace, grant write access for this directory and retry.")
+	}
+
+	tmp, err := vfs.CreateTemp(dir, tempPrefix)
+	if err != nil {
+		return errs.NewInternalError(errs.SubtypeFileIO,
+			"failed to create temporary file in refresh lock directory %q", dir).
+			WithCause(err).
+			WithHint("If running in a sandbox or read-only workspace, grant write access for this directory and retry.")
+	}
+
+	tmpName := tmp.Name()
+	closeErr := tmp.Close()
+	if removeErr := vfs.Remove(tmpName); removeErr != nil {
+		cleanupErr := removeErr
+		if closeErr != nil {
+			cleanupErr = errors.Join(removeErr,
+				fmt.Errorf("also failed to close temp file: %w", closeErr))
+		}
+		return errs.NewInternalError(errs.SubtypeFileIO,
+			"failed to clean up refresh lock write-check file %q", tmpName).
+			WithCause(cleanupErr)
+	}
+	if closeErr != nil {
+		return errs.NewInternalError(errs.SubtypeFileIO,
+			"failed to close refresh lock write-check file %q", tmpName).
+			WithCause(closeErr)
+	}
+
+	return nil
+}
+
+func ensureTokenStorageWritable(appID, userOpenID string) error {
+	if appID == "" || userOpenID == "" {
+		return errs.NewValidationError(errs.SubtypeInvalidArgument,
+			"cannot validate refresh token storage without user identity").
+			WithParam("app-id/user-open-id")
+	}
+
+	probeUserOpenID := fmt.Sprintf("%s:%s:refresh-storage-probe", appID, userOpenID)
+	probeToken := &StoredUAToken{
+		AppId:       appID,
+		UserOpenId:  probeUserOpenID,
+		AccessToken: "refresh-storage-probe",
+		Scope:       "",
+	}
+
+	if err := SetStoredToken(probeToken); err != nil {
+		return err
+	}
+	if err := RemoveStoredToken(appID, probeUserOpenID); err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/internal/errclass/codemeta_test.go b/internal/errclass/codemeta_test.go
index 0d766f3de6..90ad01b0c5 100644
--- a/internal/errclass/codemeta_test.go
+++ b/internal/errclass/codemeta_test.go
@@ -43,6 +43,19 @@ func TestLookupCodeMeta_CredentialCodes(t *testing.T) {
 	}
 }
 
+func TestLookupCodeMeta_RefreshResponseCodesRemainUnregistered(t *testing.T) {
+	codes := []int{
+		20001, 20002, 20008, 20009, 20010, 20024, 20036, 20048,
+		20063, 20066, 20067, 20068, 20069, 20070, 20072, 20074,
+	}
+
+	for _, code := range codes {
+		if got, ok := LookupCodeMeta(code); ok {
+			t.Errorf("LookupCodeMeta(%d) = %+v, want unregistered", code, got)
+		}
+	}
+}
+
 func TestLookupCodeMeta_MissingScope(t *testing.T) {
 	got, ok := LookupCodeMeta(99991679)
 	if !ok {