diff --git a/mateclaw-server/src/main/java/vip/mate/workspace/conversation/ConversationService.java b/mateclaw-server/src/main/java/vip/mate/workspace/conversation/ConversationService.java
index fea4f499..6de391be 100644
--- a/mateclaw-server/src/main/java/vip/mate/workspace/conversation/ConversationService.java
+++ b/mateclaw-server/src/main/java/vip/mate/workspace/conversation/ConversationService.java
@@ -556,6 +556,7 @@ public class ConversationService {
                 case "text" -> appendSegment(text, part.getText());
                 case "thinking", "tool_call", "parse_error" -> { /* skip — frontend reads these from contentParts directly */ }
                 case "file" -> appendSegment(text, renderFilePart(part));
+                case "image", "video", "audio", "model3d" -> appendSegment(text, renderMediaPart(part));
                 default -> appendSegment(text, part.getText());
             }
         }
@@ -614,6 +615,36 @@ public class ConversationService {
         return "[附件] " + name + "（路径: " + path + "）";
     }
 
+    /**
+     * Render an image/video/audio/3D-model content part for the LLM prompt.
+     * <p>
+     * Without this marker, media parts are invisible in the rendered text — the LLM
+     * sees only the user's accompanying text and has no idea an attachment was sent.
+     * That fails closed when the multimodal Media injection in {@code BaseAgent} is
+     * upstream-stripped (model heuristic claims vision but the actual provider drops
+     * the image), leaving the agent to ask "which image?" for an attachment the user
+     * already uploaded. The path lets file-reading tools ({@code read_file},
+     * {@code extract_document_text}, {@code detect_file_type}) work as a fallback.
+     */
+    private String renderMediaPart(MessageContentPart part) {
+        String label = switch (part.getType()) {
+            case "image" -> "[图片]";
+            case "video" -> "[视频]";
+            case "audio" -> "[音频]";
+            case "model3d" -> "[3D 模型]";
+            default -> "[附件]";
+        };
+        String name = safe(part.getFileName());
+        if (name.isBlank()) {
+            name = "未命名";
+        }
+        String path = safe(part.getPath());
+        if (path.isBlank()) {
+            return label + " " + name;
+        }
+        return label + " " + name + "（路径: " + path + "）";
+    }
+
     private void appendSegment(StringBuilder builder, String text) {
         String safeText = safe(text);
         if (safeText.isBlank()) {