fix: pass all reference images to OpenAI images.edit endpoint

bulkgen/providers/openai_image.py

@@ -185,25 +185,25 @@ async def _generate_edit(
     project_dir: Path,
     size: _SIZE | None,
 ) -> ImagesResponse:
-    """Generate an image using a reference image via the edits endpoint.
+    """Generate an image using reference images via the edits endpoint.
 
-    gpt-image-* models return b64 by default and reject ``response_format``,
-    so we only pass it for DALL-E models.
+    gpt-image-* models accept up to 16 images and return b64 by default
+    (they reject ``response_format``).  DALL-E 2 accepts only one image.
     """
-    ref_path = project_dir / reference_images[0]
-    image_bytes = ref_path.read_bytes()
+    images = [(project_dir / name).read_bytes() for name in reference_images]
+    image: bytes | list[bytes] = images[0] if len(images) == 1 else images
 
     if model.startswith("gpt-image-"):
         if size is not None:
             return await client.images.edit(
-                image=image_bytes,
+                image=image,
                 prompt=prompt,
                 model=model,
                 n=1,
                 size=size,  # pyright: ignore[reportArgumentType]
             )
         return await client.images.edit(
-            image=image_bytes,
+            image=image,
             prompt=prompt,
             model=model,
             n=1,
@@ -211,7 +211,7 @@ async def _generate_edit(
 
     if size is not None:
         return await client.images.edit(
-            image=image_bytes,
+            image=image,
             prompt=prompt,
             model=model,
             n=1,
@@ -219,7 +219,7 @@ async def _generate_edit(
             size=size,  # pyright: ignore[reportArgumentType]
         )
     return await client.images.edit(
-        image=image_bytes,
+        image=image,
         prompt=prompt,
         model=model,
         n=1,