diff --git a/core/backend/apps/ai/providers/openai_compatible.py b/core/backend/apps/ai/providers/openai_compatible.py
index dd86afa..9c9078d 100644
--- a/core/backend/apps/ai/providers/openai_compatible.py
+++ b/core/backend/apps/ai/providers/openai_compatible.py
@@ -1,10 +1,35 @@
 from typing import Any
+import io
 
 import requests
 
 from .volcano import VolcanoArkProvider
 
 
+def _downscale_ref_for_edit(data: bytes, content_type: str, max_edge: int = 2048) -> tuple[bytes, str]:
+    """图生图参考图过大时按需降采样,避免中转站(yunqi/gpt-image edits)拒收大图报 400
+    「invalid_image_file」(实测原图 6000×4000 / 5.8MB 被拒,缩到 ≤2048 即通过)。
+
+    只在「最长边 > max_edge 或体积 > 4MB」时才处理,否则原样返回(不损质量)。
+    三视图等成品输出 ≤1536px,参考图 2048 已 ≥ 输出分辨率 → 降到 2048 对成品零损失,只是去掉
+    成品用不上的冗余像素。保留透明通道(有 alpha 存 PNG,否则 JPEG q92)。解析失败则原样放行。"""
+    try:
+        from PIL import Image
+
+        im = Image.open(io.BytesIO(data))
+        if max(im.size) <= max_edge and len(data) <= 4_000_000:
+            return data, content_type
+        im.thumbnail((max_edge, max_edge))
+        out = io.BytesIO()
+        if im.mode in ("RGBA", "LA", "P"):
+            im.convert("RGBA").save(out, format="PNG", optimize=True)
+            return out.getvalue(), "image/png"
+        im.convert("RGB").save(out, format="JPEG", quality=92)
+        return out.getvalue(), "image/jpeg"
+    except Exception:  # noqa: BLE001 — 非图/解析失败:原样发,让上游/中转站决定,不因压缩环节中断生成
+        return data, content_type
+
+
 class OpenAICompatibleProvider(VolcanoArkProvider):
     """通用 OpenAI 兼容中转站适配器(tokenssr / yunqi / 任意 New-API 网关)。
 
@@ -78,12 +103,14 @@ class OpenAICompatibleProvider(VolcanoArkProvider):
         for idx, ref in enumerate(images or []):
             fileobj, content_type = self.media_to_bytes(ref)
             content_type = content_type or "image/png"
+            # 过大参考图按需降采样(≤2048,对成品零损失),否则中转站拒收报 400 invalid_image_file
+            img_bytes, content_type = _downscale_ref_for_edit(fileobj.getvalue(), content_type)
             ext = "png"
             if "jpeg" in content_type or "jpg" in content_type:
                 ext = "jpg"
             elif "webp" in content_type:
                 ext = "webp"
-            files.append(("image[]", (f"ref{idx + 1}.{ext}", fileobj.getvalue(), content_type)))
+            files.append(("image[]", (f"ref{idx + 1}.{ext}", img_bytes, content_type)))
         if not files:
             raise ValueError("image_edit 至少需要一张参考图")
         data = {"model": model, "prompt": prompt, "size": size, "n": "1"}