为绑定区域校验引入类型错误

用 ZeroDimension 和 OutOfBounds 区分边界校验失败

补充 typed error 单元测试并保留展示层中文文案

apps/ai-game-creator-shell/src-tauri/src/ui_editor/commands/separation/model/binding.rs

@@ -2,6 +2,23 @@ use crate::ui_editor::utils::NodeId;
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
 
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum BindingAreaValidationError {
+    ZeroDimension,
+    OutOfBounds,
+}
+
+impl std::fmt::Display for BindingAreaValidationError {
+    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        formatter.write_str(match self {
+            Self::ZeroDimension => "BindingArea 宽度和高度必须大于 0",
+            Self::OutOfBounds => "BindingArea 超出处理图边界",
+        })
+    }
+}
+
+impl std::error::Error for BindingAreaValidationError {}
+
 #[derive(Clone, Copy, Debug, Deserialize, Eq, PartialEq, Serialize, JsonSchema)]
 #[schemars(deny_unknown_fields)]
 pub struct BindingArea {
@@ -12,9 +29,9 @@ pub struct BindingArea {
 }
 
 impl BindingArea {
-    pub fn validate_in(&self, w: u32, h: u32) -> Result<(), String> {
+    pub fn validate_in(&self, w: u32, h: u32) -> Result<(), BindingAreaValidationError> {
         if self.width_px == 0 || self.height_px == 0 {
-            return Err("BindingArea 宽度和高度必须大于 0".into());
+            return Err(BindingAreaValidationError::ZeroDimension);
         }
         if self
             .global_pos_x_px
@@ -25,7 +42,7 @@ impl BindingArea {
                 .checked_add(self.height_px)
                 .is_none_or(|v| v > h)
         {
-            return Err("BindingArea 超出处理图边界".into());
+            return Err(BindingAreaValidationError::OutOfBounds);
         }
         Ok(())
     }
@@ -48,3 +65,33 @@ pub enum BindingDecision {
 pub struct BindingResp {
     pub decisions: Vec<BindingDecision>,
 }
+
+#[cfg(test)]
+mod tests {
+    use super::{BindingArea, BindingAreaValidationError};
+
+    #[test]
+    fn validates_binding_area_with_typed_errors() {
+        let zero = BindingArea {
+            global_pos_x_px: 0,
+            global_pos_y_px: 0,
+            width_px: 0,
+            height_px: 1,
+        };
+        assert_eq!(
+            zero.validate_in(10, 10),
+            Err(BindingAreaValidationError::ZeroDimension)
+        );
+
+        let outside = BindingArea {
+            global_pos_x_px: 10,
+            global_pos_y_px: 0,
+            width_px: 1,
+            height_px: 1,
+        };
+        assert_eq!(
+            outside.validate_in(10, 10),
+            Err(BindingAreaValidationError::OutOfBounds)
+        );
+    }
+}