No more transparent bg param option

Author: pvzig

.ENV.example

@@ -8,7 +8,7 @@ GENERATED_IMAGES_BUCKET=your-generated-images-bucket
 OPENAI_API_KEY=your-openai-api-key
 AWS_ACCESS_KEY_ID=your-aws-access-key-id
 AWS_SECRET_ACCESS_KEY=your-aws-secret-access-key
-OPENAI_IMAGE_MODEL=gpt-image-1.5
+OPENAI_IMAGE_MODEL=gpt-image-2
 IMAGE_GEN_PREFIX=generated/v2
 
 BACKEND_HOST=127.0.0.1

Backend/Sources/Server/Model/ImageGenRequest.swift

@@ -1,13 +1,11 @@
 struct ImageGenRequest: Encodable {
-    let background: String
     let model: String
     let outputFormat: String
     let prompt: String
     let quality: String
     let size: String
 
     enum CodingKeys: String, CodingKey {
-        case background
         case model
         case outputFormat = "output_format"
         case prompt

Backend/Sources/Server/OpenAiClient.swift

@@ -21,7 +21,6 @@ struct OpenAiClient {
 
     func generateImage(prompt: String) async throws -> Data {
         let payload = ImageGenRequest(
-            background: "transparent",
             model: environment.openAIModel,
             outputFormat: "png",
             prompt: prompt,

Backend/Tests/CoreTests/EnvironmentTests.swift

@@ -11,7 +11,7 @@ struct EnvironmentTests {
                 "HOST": "127.0.0.1",
                 "IMAGE_GEN_PREFIX": "/generated/v2/",
                 "OPENAI_API_KEY": "secret",
-                "OPENAI_IMAGE_MODEL": "gpt-image-1.5",
+                "OPENAI_IMAGE_MODEL": "gpt-image-2",
                 "PORT": "8080",
             ]
         )
@@ -21,7 +21,7 @@ struct EnvironmentTests {
         #expect(environment.generatedImagesPrefix == "generated/v2")
         #expect(environment.hostname == "127.0.0.1")
         #expect(environment.openAIAPIKey == "secret")
-        #expect(environment.openAIModel == "gpt-image-1.5")
+        #expect(environment.openAIModel == "gpt-image-2")
         #expect(environment.port == 8080)
     }
 
@@ -34,7 +34,7 @@ struct EnvironmentTests {
                 "GENERATED_IMAGES_BUCKET": "bytesized-generated-images",
                 "IMAGE_GEN_PREFIX": "generated/v2",
                 "OPENAI_API_KEY": "secret",
-                "OPENAI_IMAGE_MODEL": "gpt-image-1.5",
+                "OPENAI_IMAGE_MODEL": "gpt-image-2",
             ]
         )
 
@@ -50,7 +50,7 @@ struct EnvironmentTests {
                     "GENERATED_IMAGES_BUCKET": "bytesized-generated-images",
                     "IMAGE_GEN_PREFIX": "generated/v2",
                     "OPENAI_API_KEY": "secret",
-                    "OPENAI_IMAGE_MODEL": "gpt-image-1.5",
+                    "OPENAI_IMAGE_MODEL": "gpt-image-2",
                     "PORT": "8080",
                 ]
             )
@@ -67,7 +67,7 @@ struct EnvironmentTests {
                     "GENERATED_IMAGES_BUCKET": "bytesized-generated-images",
                     "IMAGE_GEN_PREFIX": "generated/v2",
                     "OPENAI_API_KEY": "secret",
-                    "OPENAI_IMAGE_MODEL": "gpt-image-1.5",
+                    "OPENAI_IMAGE_MODEL": "gpt-image-2",
                 ]
             )
         }

SPEC.md

@@ -10,7 +10,7 @@ Implement a web app where:
 - When the daily generation budget is exhausted, the backend returns a random previously generated image instead of requesting a new one.
 - The backend waits for image generation to finish before replying.
 - The final image is rendered from a public S3 HTTPS URL.
-- The image is generated by the OpenAI image generation API using the fixed model `gpt-image-1.5`.
+- The image is generated by the OpenAI image generation API using the fixed model `gpt-image-2`.
 - The generation prompt should use the request's origin country when the server can resolve it from the client IP through `country.is`, and otherwise fall back to a generic worldwide prompt.
 - The backend performs `country.is` lookups and OpenAI image-generation requests with AsyncHTTPClient.
 - The backend uses a long-lived Hummingbird server.
@@ -148,7 +148,7 @@ Rules:
   - Instruct the model to show exactly one hero food item with no combo meals, side dishes, drinks, menus, flags, labels, or text.
   - Instruct the model to avoid defaulting to globally common fast food such as hamburgers, fries, pizza, or hot dogs unless the subject is a distinctive named local variation.
   - Fall back to the same prompt structure scoped to somewhere in the world when the client IP or country cannot be resolved.
-  - Call the OpenAI image generation API with model `gpt-image-1.5`.
+  - Call the OpenAI image generation API with model `gpt-image-2`, PNG output.
   - Upload the PNG to the generated image key used for the dated generation pool.
   - Upload the same PNG to the daily page-cache key.
   - Return the page-cache `url`.