diff --git a/server-rs/crates/platform-tripo/src/common/error.rs b/server-rs/crates/platform-tripo/src/common/error.rs
index e599b1d49..6697c95c9 100644
--- a/server-rs/crates/platform-tripo/src/common/error.rs
+++ b/server-rs/crates/platform-tripo/src/common/error.rs
@@ -62,6 +62,8 @@ impl fmt::Display for TripoField {
 pub enum TripoValidationReason {
     Required,
     InvalidCombination,
+    /// 取值超出该字段允许的长度或范围，与「参数组合互斥」区分开。
+    OutOfRange,
 }
 
 impl fmt::Display for TripoValidationReason {
@@ -69,6 +71,7 @@ impl fmt::Display for TripoValidationReason {
         f.write_str(match self {
             Self::Required => "required",
             Self::InvalidCombination => "invalid combination",
+            Self::OutOfRange => "out of range",
         })
     }
 }
diff --git a/server-rs/crates/platform-tripo/src/common/validation.rs b/server-rs/crates/platform-tripo/src/common/validation.rs
index 00dfaa4f6..ee19b7da8 100644
--- a/server-rs/crates/platform-tripo/src/common/validation.rs
+++ b/server-rs/crates/platform-tripo/src/common/validation.rs
@@ -173,7 +173,7 @@ pub(crate) fn validate_generation_options(
         if face_limit < minimum || face_limit > maximum {
             return Err(invalid(
                 Some(TripoField::FaceLimit),
-                TripoValidationReason::InvalidCombination,
+                TripoValidationReason::OutOfRange,
                 &format!(
                     "face_limit must be between {minimum} and {maximum} for the selected model and options"
                 ),
diff --git a/server-rs/crates/platform-tripo/src/text_to_model/validation.rs b/server-rs/crates/platform-tripo/src/text_to_model/validation.rs
index 472379133..1c3d6751e 100644
--- a/server-rs/crates/platform-tripo/src/text_to_model/validation.rs
+++ b/server-rs/crates/platform-tripo/src/text_to_model/validation.rs
@@ -16,7 +16,7 @@ pub fn validate_text_to_model_params(params: &Model3dTextToModelParams) -> Resul
     if params.prompt.chars().count() > 1024 {
         return Err(TripoError::InvalidParameters {
             field: Some(TripoField::Prompt),
-            reason: TripoValidationReason::InvalidCombination,
+            reason: TripoValidationReason::OutOfRange,
             message: "prompt must not exceed 1024 characters".into(),
         });
     }
@@ -27,7 +27,7 @@ pub fn validate_text_to_model_params(params: &Model3dTextToModelParams) -> Resul
     {
         return Err(TripoError::InvalidParameters {
             field: Some(TripoField::NegativePrompt),
-            reason: TripoValidationReason::InvalidCombination,
+            reason: TripoValidationReason::OutOfRange,
             message: "negative_prompt must not exceed 255 characters".into(),
         });
     }