diff --git a/server-rs/crates/platform-tripo/src/common/types.rs b/server-rs/crates/platform-tripo/src/common/types.rs
index 455779e29..327ac73a7 100644
--- a/server-rs/crates/platform-tripo/src/common/types.rs
+++ b/server-rs/crates/platform-tripo/src/common/types.rs
@@ -197,7 +197,42 @@ impl TripoDownloadedArtifact {
                     && extension.len() <= MAX_ARTIFACT_FILE_EXTENSION_LEN
                     && extension.bytes().all(|byte| byte.is_ascii_alphanumeric())
             })
-            .unwrap_or("glb");
-        format!("{name}.{extension}")
+            .unwrap_or_else(|| fallback_artifact_extension(self.content_type.as_deref()));
+        format!("{}.{extension}", sanitize_artifact_file_stem(name))
+    }
+}
+
+/// URL 路径给不出可用扩展名时按 content type 兜底：同一条下载路径也服务预览图，
+/// 一律写 `.glb` 会把 PNG / JPEG 产物写成模型文件名。
+fn fallback_artifact_extension(content_type: Option<&str>) -> &'static str {
+    let content_type = content_type.unwrap_or_default();
+    if content_type.starts_with("image/png") {
+        "png"
+    } else if content_type.starts_with("image/jpeg") {
+        "jpg"
+    } else if content_type.starts_with("image/webp") {
+        "webp"
+    } else {
+        "glb"
+    }
+}
+
+/// 文件名主干同样来自不可信输入：路径分隔符与 `..` 会让拼接结果逃出目标目录，
+/// 这里统一中性化成安全字符。
+fn sanitize_artifact_file_stem(name: &str) -> String {
+    let sanitized: String = name
+        .chars()
+        .map(|ch| {
+            if ch.is_ascii_alphanumeric() || matches!(ch, '-' | '_') {
+                ch
+            } else {
+                '_'
+            }
+        })
+        .collect();
+    if sanitized.trim_matches('_').is_empty() {
+        "artifact".to_string()
+    } else {
+        sanitized
     }
 }