diff --git a/crates/erp-ai/src/error.rs b/crates/erp-ai/src/error.rs
index 5dff165..f3d4e35 100644
--- a/crates/erp-ai/src/error.rs
+++ b/crates/erp-ai/src/error.rs
@@ -31,6 +31,21 @@ pub enum AiError {
 
     #[error("数据库错误: {0}")]
     DbError(String),
+
+    #[error("AI 配额已耗尽: {reason}")]
+    QuotaExhausted { tenant_id: uuid::Uuid, reason: String },
+
+    #[error("缓存错误: {0}")]
+    CacheError(String),
+
+    #[error("知识库错误: {0}")]
+    KnowledgeError(String),
+
+    #[error("分析队列错误: {0}")]
+    QueueError(String),
+
+    #[error("AI 配置错误: {0}")]
+    ConfigError(String),
 }
 
 impl From<AiError> for AppError {
@@ -43,6 +58,7 @@ impl From<AiError> for AppError {
                 AppError::Internal(format!("AI 提供商 {p} 不可用"))
             }
             AiError::RateLimitExceeded => AppError::TooManyRequests,
+            AiError::QuotaExhausted { .. } => AppError::TooManyRequests,
             AiError::VersionMismatch => AppError::VersionMismatch,
             AiError::DbError(msg) => AppError::Internal(msg),
             other => AppError::Internal(other.to_string()),
@@ -161,4 +177,54 @@ mod tests {
             other => panic!("期望 AppError::Internal，得到 {:?}", other),
         }
     }
+
+    #[test]
+    fn quota_exhausted_maps_to_429() {
+        let err = AiError::QuotaExhausted {
+            tenant_id: uuid::Uuid::now_v7(),
+            reason: "monthly budget".into(),
+        };
+        let app: AppError = err.into();
+        assert!(matches!(app, AppError::TooManyRequests));
+    }
+
+    #[test]
+    fn cache_error_maps_to_internal() {
+        let err = AiError::CacheError("redis timeout".into());
+        let app: AppError = err.into();
+        match app {
+            AppError::Internal(msg) => assert!(msg.contains("redis timeout")),
+            other => panic!("期望 AppError::Internal，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn knowledge_error_maps_to_internal() {
+        let err = AiError::KnowledgeError("rule not found".into());
+        let app: AppError = err.into();
+        match app {
+            AppError::Internal(msg) => assert!(msg.contains("rule not found")),
+            other => panic!("期望 AppError::Internal，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn queue_error_maps_to_internal() {
+        let err = AiError::QueueError("queue full".into());
+        let app: AppError = err.into();
+        match app {
+            AppError::Internal(msg) => assert!(msg.contains("queue full")),
+            other => panic!("期望 AppError::Internal，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn config_error_maps_to_internal() {
+        let err = AiError::ConfigError("missing provider".into());
+        let app: AppError = err.into();
+        match app {
+            AppError::Internal(msg) => assert!(msg.contains("missing provider")),
+            other => panic!("期望 AppError::Internal，得到 {:?}", other),
+        }
+    }
 }