From 9b560c3e1cae579f4427f4c647d91e9a1c5cbdad Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9D=A8=E7=9D=BF?= <595403043@qq.com>
Date: Tue, 15 Jul 2025 14:27:54 +0800
Subject: [PATCH] fix: modality length mismatch with image_data (#7887)

---
 python/sglang/srt/managers/io_struct.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/python/sglang/srt/managers/io_struct.py b/python/sglang/srt/managers/io_struct.py
index 9b2768160..745b7a2da 100644
--- a/python/sglang/srt/managers/io_struct.py
+++ b/python/sglang/srt/managers/io_struct.py
@@ -297,6 +297,9 @@ class GenerateReqInput:
                         self.modalities.append("image")
                     elif len(self.image_data[i]) > 1:
                         self.modalities.append("multi-images")
+                    else:
+                        # Ensure len(self.modalities) == len(self.image_data)
+                        self.modalities.append(None)
                 # Expand parallel_sample_num
                 self.image_data = self.image_data * self.parallel_sample_num
                 self.modalities = self.modalities * self.parallel_sample_num