fix(server): route OpenAI image edits by reference conditioning support (#2167)

examples/server/openai_edit_policy.h

@@ -0,0 +1,44 @@
+#ifndef __SD_EXAMPLES_SERVER_OPENAI_EDIT_POLICY_H__
+#define __SD_EXAMPLES_SERVER_OPENAI_EDIT_POLICY_H__
+
+#include "common/resource_owners.hpp"
+
+enum class OpenAIEditInitImageAction {
+    KeepExisting,
+    UseUploaded,
+    Clear,
+};
+
+inline bool openai_edit_uses_uploaded_image_as_init(bool supports_ref_image_conditioning,
+                                                    bool has_ref_images,
+                                                    bool has_mask,
+                                                    bool has_explicit_strength_override) {
+    return !supports_ref_image_conditioning || !has_ref_images || has_mask || has_explicit_strength_override;
+}
+
+inline OpenAIEditInitImageAction apply_openai_edit_init_image_policy(
+    SDImageOwner& init_image,
+    SDImageOwner& uploaded_image,
+    bool uploaded_image_was_first_reference,
+    bool supports_ref_image_conditioning,
+    bool has_ref_images,
+    bool has_mask,
+    bool has_extra_init_image_override,
+    bool has_explicit_strength_override) {
+    if (!uploaded_image_was_first_reference || has_extra_init_image_override) {
+        return OpenAIEditInitImageAction::KeepExisting;
+    }
+
+    if (openai_edit_uses_uploaded_image_as_init(supports_ref_image_conditioning,
+                                                has_ref_images,
+                                                has_mask,
+                                                has_explicit_strength_override)) {
+        init_image = std::move(uploaded_image);
+        return OpenAIEditInitImageAction::UseUploaded;
+    }
+
+    init_image.reset();
+    return OpenAIEditInitImageAction::Clear;
+}
+
+#endif  // __SD_EXAMPLES_SERVER_OPENAI_EDIT_POLICY_H__