feat: update image generation model configuration

- Change model from dall-e-2 to gpt-image-1-mini in README and tests
- Update model key constants in test files to use proper API constants

Signed-off-by: Hrushikesh Patil <[email protected]>

Author: nutanix-Hrushikesh

cmd/aigw/README.md

@@ -74,7 +74,7 @@ Here are values we use for Ollama:
          -X POST http://localhost:1975/v1/images/generations \
          -H "Authorization: Bearer unused" \
          -H "Content-Type: application/json" \
-        -d '{"model":"gpt-image-1-mini","prompt":"A watercolor painting of a red fox in a birch forest","size":"1024x1024","quality":"low"}' \
+         -d '{"model":"gpt-image-1-mini","prompt":"A watercolor painting of a red fox in a birch forest","size":"1024x1024","quality":"low"}' \
          | jq -r '.data[0].b64_json' | base64 -d > image.png
        ```
 

internal/extproc/imagegeneration_processor_test.go

@@ -109,7 +109,7 @@ func Test_imageGenerationProcessorRouterFilter_ProcessRequestBody(t *testing.T)
 
 	t.Run("ok", func(t *testing.T) {
 		headers := map[string]string{":path": "/v1/images/generations"}
-		const modelKey = "x-ai-gateway-model-key"
+		const modelKey = "x-ai-eg-model"
 		p := &imageGenerationProcessorRouterFilter{
 			config:         &processorConfig{},
 			requestHeaders: headers,
@@ -246,7 +246,7 @@ func Test_imageGenerationProcessorUpstreamFilter_ProcessResponseBody(t *testing.
 					},
 				},
 			},
-			requestHeaders:    map[string]string{"x-aigw-model": "ai_gateway_llm"},
+			requestHeaders:    map[string]string{internalapi.ModelNameHeaderKeyDefault: "ai_gateway_llm"},
 			responseHeaders:   map[string]string{":status": "200"},
 			backendName:       "some_backend",
 			modelNameOverride: "ai_gateway_llm",
@@ -261,16 +261,16 @@ func Test_imageGenerationProcessorUpstreamFilter_ProcessResponseBody(t *testing.
 
 		md := res.DynamicMetadata
 		require.NotNil(t, md)
-		require.Equal(t, float64(123), md.Fields["ai_gateway_llm_ns"].
+		require.Equal(t, float64(123), md.Fields[internalapi.AIGatewayFilterMetadataNamespace].
 			GetStructValue().Fields["output_token_usage"].GetNumberValue())
-		require.Equal(t, float64(1), md.Fields["ai_gateway_llm_ns"].
+		require.Equal(t, float64(1), md.Fields[internalapi.AIGatewayFilterMetadataNamespace].
 			GetStructValue().Fields["input_token_usage"].GetNumberValue())
-		require.Equal(t, float64(54321), md.Fields["ai_gateway_llm_ns"].
+		require.Equal(t, float64(54321), md.Fields[internalapi.AIGatewayFilterMetadataNamespace].
 			GetStructValue().Fields["cel_int"].GetNumberValue())
-		require.Equal(t, float64(9999), md.Fields["ai_gateway_llm_ns"].
+		require.Equal(t, float64(9999), md.Fields[internalapi.AIGatewayFilterMetadataNamespace].
 			GetStructValue().Fields["cel_uint"].GetNumberValue())
-		require.Equal(t, "ai_gateway_llm", md.Fields["ai_gateway_llm_ns"].GetStructValue().Fields["model_name_override"].GetStringValue())
-		require.Equal(t, "some_backend", md.Fields["ai_gateway_llm_ns"].GetStructValue().Fields["backend_name"].GetStringValue())
+		require.Equal(t, "ai_gateway_llm", md.Fields[internalapi.AIGatewayFilterMetadataNamespace].GetStructValue().Fields["model_name_override"].GetStringValue())
+		require.Equal(t, "some_backend", md.Fields[internalapi.AIGatewayFilterMetadataNamespace].GetStructValue().Fields["backend_name"].GetStringValue())
 	})
 
 	// Verify we record failure for non-2xx responses and do it exactly once (defer suppressed).

tests/internal/testopenai/cassettes/image-generation-basic.yaml

@@ -6,14 +6,14 @@ interactions:
     proto: HTTP/1.1
     proto_major: 1
     proto_minor: 1
-    content_length: 105
+    content_length: 139
     host: api.openai.com
-    body: "{\n  \"model\": \"dall-e-2\",\n  \"prompt\": \"A simple black-and-white line drawing of a cat playing with yarn\"\n}"
+    body: "{\n  \"model\": \"gpt-image-1-mini\",\n  \"prompt\": \"A simple black-and-white line drawing of a cat playing with yarn\",\n  \"size\": \"1024x1024\",\n  \"quality\": \"low\"\n}"
     headers:
       Accept-Encoding:
       - gzip
       Content-Length:
-      - "105"
+      - "139"
       Content-Type:
       - application/json
       User-Agent:
@@ -25,22 +25,22 @@ interactions:
     proto_major: 2
     proto_minor: 0
     content_length: 544
-    body: "{\n  \"created\": 1759925706,\n  \"data\": [\n    {\n      \"url\": \"https://oaidalleapiprodscus.blob.core.windows.net/private/org-lKxIBdltrjcFbzboW0t1hthB/user-EdKNxj0PjYS29CfjUcR77ybc/img-MigVWgAi6l5W3B31L6imFob3.png?st=2025-10-08T11%3A15%3A05Z&se=2025-10-08T13%3A15%3A05Z&sp=r&sv=2024-08-04&sr=b&rscd=inline&rsct=image/png&skoid=52f8f7b3-ca8d-4b21-9807-8b9df114d84c&sktid=a48cca56-e6da-484e-a814-9c849652bcb3&skt=2025-10-08T12%3A15%3A05Z&ske=2025-10-09T12%3A15%3A05Z&sks=b&skv=2024-08-04&sig=ex3I6RoFVH9hfNst8oloGtfBVA3o2aXvTI4cFtLVzlE%3D\"\n    }\n  ]\n}"
+    body: "{\n  \"created\": 1760092079,\n  \"data\": [\n    {\n      \"url\": \"https://oaidalleapiprodscus.blob.core.windows.net/private/org-lKxIBdltrjcFbzboW0t1hthB/user-EdKNxj0PjYS29CfjUcR77ybc/img-3Ah2ERYmeJLYrRlxnuWPFpXG.png?st=2025-10-10T09%3A27%3A58Z&se=2025-10-10T11%3A27%3A58Z&sp=r&sv=2024-08-04&sr=b&rscd=inline&rsct=image/png&skoid=475fd488-6c59-44a5-9aa9-31c4db451bea&sktid=a48cca56-e6da-484e-a814-9c849652bcb3&skt=2025-10-10T10%3A27%3A58Z&ske=2025-10-11T10%3A27%3A58Z&sks=b&skv=2024-08-04&sig=IlzMauzcIHqE5/JLQsiMglI0mqbGlrpQC/mvJz4TYuc%3D\"\n    }\n  ]\n}"
     headers:
       Alt-Svc:
       - h3=":443"; ma=86400
       Cf-Cache-Status:
       - DYNAMIC
       Cf-Ray:
-      - 98b58f7bde648af7-BOM
+      - 98c56d4f2dd889f6-BOM
       Content-Length:
       - "544"
       Content-Type:
       - application/json
       Date:
-      - Wed, 08 Oct 2025 12:15:06 GMT
+      - Fri, 10 Oct 2025 10:27:59 GMT
       Openai-Processing-Ms:
-      - "13265"
+      - "13023"
       Openai-Project:
       - proj_Ro6stNUOKIiLVqRr1zdjaFoh
       Openai-Version:
@@ -52,9 +52,9 @@ interactions:
       X-Content-Type-Options:
       - nosniff
       X-Envoy-Upstream-Service-Time:
-      - "13269"
+      - "13027"
       X-Request-Id:
-      - req_c643aaa7f52258b2192d4c133d117e43
+      - req_54999507941c487a8f1997287aaa8cf6
     status: 200 OK
     code: 200
-    duration: 13.632879292s
+    duration: 14.290895958s