diff --git a/backend/internal/pkg/openai/constants.go b/backend/internal/pkg/openai/constants.go
index a863a19f81..772143ac92 100644
--- a/backend/internal/pkg/openai/constants.go
+++ b/backend/internal/pkg/openai/constants.go
@@ -45,6 +45,9 @@ func DefaultModelIDs() []string {
 // DefaultTestModel default model for testing OpenAI accounts
 const DefaultTestModel = "gpt-5.4"
 
+// CodexUsageProbeModel is the model used for OAuth Codex usage probes.
+const CodexUsageProbeModel = "codex-auto-review"
+
 // DefaultInstructions default instructions for non-Codex CLI requests.
 // 内容为真实 Codex CLI 的 GPT-5-Codex base prompt（codex 系模型默认）。
 //
diff --git a/backend/internal/service/account_usage_service.go b/backend/internal/service/account_usage_service.go
index 084d153ff2..5dc1b1b071 100644
--- a/backend/internal/service/account_usage_service.go
+++ b/backend/internal/service/account_usage_service.go
@@ -830,7 +830,7 @@ func (s *AccountUsageService) probeOpenAICodexSnapshot(ctx context.Context, acco
 	if accessToken == "" && !account.IsOpenAIAgentIdentity() {
 		return nil, fmt.Errorf("no access token available")
 	}
-	modelID := openaipkg.DefaultTestModel
+	modelID := openaipkg.CodexUsageProbeModel
 	payload := createOpenAITestPayload(modelID, true)
 	payloadBytes, err := json.Marshal(payload)
 	if err != nil {