fix(openai): honor versioned image base URLs

backend/internal/service/account_test_service.go

@@ -1227,7 +1227,7 @@ func (s *AccountTestService) testOpenAIImageAPIKey(c *gin.Context, ctx context.C
 	if err != nil {
 		return s.sendErrorAndEnd(c, fmt.Sprintf("Invalid base URL: %s", err.Error()))
 	}
-	apiURL := strings.TrimSuffix(normalizedBaseURL, "/") + "/v1/images/generations"
+	apiURL := buildOpenAIImagesURL(normalizedBaseURL, openAIImagesGenerationsEndpoint)
 
 	// Set SSE headers
 	c.Writer.Header().Set("Content-Type", "text/event-stream")

backend/internal/service/account_test_service_openai_image_test.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/Wei-Shaw/sub2api/internal/config"
 	"github.com/gin-gonic/gin"
 	"github.com/stretchr/testify/require"
 )
@@ -48,3 +49,42 @@ func TestAccountTestService_OpenAIImageOAuthHandlesOutputItemDoneFallback(t *tes
 	require.Contains(t, rec.Body.String(), "data:image/png;base64,aGVsbG8=")
 	require.Contains(t, rec.Body.String(), "\"success\":true")
 }
+
+func TestAccountTestService_OpenAIImageAPIKeyUsesConfiguredV1BaseURL(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	rec := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(rec)
+	c.Request = httptest.NewRequest(http.MethodPost, "/api/v1/admin/accounts/1/test", nil)
+
+	upstream := &httpUpstreamRecorder{
+		resp: &http.Response{
+			StatusCode: http.StatusOK,
+			Header: http.Header{
+				"Content-Type": []string{"application/json"},
+			},
+			Body: io.NopCloser(strings.NewReader(`{"data":[{"b64_json":"aGVsbG8=","revised_prompt":"draw a cat"}]}`)),
+		},
+	}
+	svc := &AccountTestService{
+		httpUpstream: upstream,
+		cfg:          &config.Config{},
+	}
+	account := &Account{
+		ID:       54,
+		Name:     "openai-apikey",
+		Platform: PlatformOpenAI,
+		Type:     AccountTypeAPIKey,
+		Credentials: map[string]any{
+			"api_key":  "test-api-key",
+			"base_url": "https://image-upstream.example/v1",
+		},
+	}
+
+	err := svc.testOpenAIImageAPIKey(c, context.Background(), account, "gpt-image-2", "draw a cat")
+	require.NoError(t, err)
+	require.NotNil(t, upstream.lastReq)
+	require.Equal(t, "https://image-upstream.example/v1/images/generations", upstream.lastReq.URL.String())
+	require.Equal(t, "Bearer test-api-key", upstream.lastReq.Header.Get("Authorization"))
+	require.Contains(t, rec.Body.String(), "data:image/png;base64,aGVsbG8=")
+	require.Contains(t, rec.Body.String(), "\"success\":true")
+}

backend/internal/service/openai_images_test.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/Wei-Shaw/sub2api/internal/config"
 	"github.com/gin-gonic/gin"
 	"github.com/stretchr/testify/require"
 	"github.com/tidwall/gjson"
@@ -258,6 +259,25 @@ func TestAccountSupportsOpenAIImageCapability_OAuthSupportsNative(t *testing.T)
 	require.True(t, account.SupportsOpenAIImageCapability(OpenAIImagesCapabilityNative))
 }
 
+func TestBuildOpenAIImagesURL_HandlesVersionedBaseURL(t *testing.T) {
+	require.Equal(t,
+		"https://image-upstream.example/v1/images/generations",
+		buildOpenAIImagesURL("https://image-upstream.example/v1", openAIImagesGenerationsEndpoint),
+	)
+	require.Equal(t,
+		"https://image-upstream.example/v1/images/edits",
+		buildOpenAIImagesURL("https://image-upstream.example/v1/", openAIImagesEditsEndpoint),
+	)
+	require.Equal(t,
+		"https://image-upstream.example/v1/images/generations",
+		buildOpenAIImagesURL("https://image-upstream.example", openAIImagesGenerationsEndpoint),
+	)
+	require.Equal(t,
+		"https://image-upstream.example/v1/images/generations",
+		buildOpenAIImagesURL("https://image-upstream.example/v1/images/generations", openAIImagesGenerationsEndpoint),
+	)
+}
+
 type openAIImageTestSSEEvent struct {
 	Name string
 	Data string
@@ -371,6 +391,124 @@ func TestOpenAIGatewayServiceForwardImages_OAuthUsesResponsesAPI(t *testing.T) {
 	require.Equal(t, "draw a cat", gjson.Get(rec.Body.String(), "data.0.revised_prompt").String())
 }
 
+func TestOpenAIGatewayServiceForwardImages_APIKeyGenerationUsesConfiguredV1BaseURL(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	body := []byte(`{"model":"gpt-image-2","prompt":"draw a cat","response_format":"b64_json"}`)
+
+	req := httptest.NewRequest(http.MethodPost, "/v1/images/generations", bytes.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+	rec := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(rec)
+	c.Request = req
+
+	svc := &OpenAIGatewayService{
+		cfg: &config.Config{},
+		httpUpstream: &httpUpstreamRecorder{
+			resp: &http.Response{
+				StatusCode: http.StatusOK,
+				Header: http.Header{
+					"Content-Type": []string{"application/json"},
+					"X-Request-Id": []string{"req_img_apikey"},
+				},
+				Body: io.NopCloser(strings.NewReader(`{"created":1710000007,"data":[{"b64_json":"aGVsbG8=","revised_prompt":"draw a cat"}]}`)),
+			},
+		},
+	}
+	parsed, err := svc.ParseOpenAIImagesRequest(c, body)
+	require.NoError(t, err)
+
+	account := &Account{
+		ID:       6,
+		Name:     "openai-apikey",
+		Platform: PlatformOpenAI,
+		Type:     AccountTypeAPIKey,
+		Credentials: map[string]any{
+			"api_key":  "test-api-key",
+			"base_url": "https://image-upstream.example/v1",
+		},
+	}
+
+	result, err := svc.ForwardImages(context.Background(), c, account, body, parsed, "")
+	require.NoError(t, err)
+	require.NotNil(t, result)
+	require.Equal(t, 1, result.ImageCount)
+	require.Equal(t, "gpt-image-2", result.Model)
+	require.Equal(t, "gpt-image-2", result.UpstreamModel)
+
+	upstream, ok := svc.httpUpstream.(*httpUpstreamRecorder)
+	require.True(t, ok)
+	require.NotNil(t, upstream.lastReq)
+	require.Equal(t, "https://image-upstream.example/v1/images/generations", upstream.lastReq.URL.String())
+	require.Equal(t, "Bearer test-api-key", upstream.lastReq.Header.Get("Authorization"))
+	require.Equal(t, "application/json", upstream.lastReq.Header.Get("Content-Type"))
+	require.Equal(t, "gpt-image-2", gjson.GetBytes(upstream.lastBody, "model").String())
+	require.Equal(t, http.StatusOK, rec.Code)
+	require.Equal(t, "aGVsbG8=", gjson.Get(rec.Body.String(), "data.0.b64_json").String())
+}
+
+func TestOpenAIGatewayServiceForwardImages_APIKeyEditUsesConfiguredV1BaseURL(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+
+	var body bytes.Buffer
+	writer := multipart.NewWriter(&body)
+	require.NoError(t, writer.WriteField("model", "gpt-image-2"))
+	require.NoError(t, writer.WriteField("prompt", "replace background"))
+	imagePart, err := writer.CreateFormFile("image", "source.png")
+	require.NoError(t, err)
+	_, err = imagePart.Write([]byte("png-image-content"))
+	require.NoError(t, err)
+	require.NoError(t, writer.Close())
+
+	req := httptest.NewRequest(http.MethodPost, "/v1/images/edits", bytes.NewReader(body.Bytes()))
+	req.Header.Set("Content-Type", writer.FormDataContentType())
+	rec := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(rec)
+	c.Request = req
+
+	svc := &OpenAIGatewayService{
+		cfg: &config.Config{},
+		httpUpstream: &httpUpstreamRecorder{
+			resp: &http.Response{
+				StatusCode: http.StatusOK,
+				Header: http.Header{
+					"Content-Type": []string{"application/json"},
+					"X-Request-Id": []string{"req_img_edit_apikey"},
+				},
+				Body: io.NopCloser(strings.NewReader(`{"created":1710000008,"data":[{"b64_json":"ZWRpdGVk","revised_prompt":"replace background"}]}`)),
+			},
+		},
+	}
+	parsed, err := svc.ParseOpenAIImagesRequest(c, body.Bytes())
+	require.NoError(t, err)
+
+	account := &Account{
+		ID:       7,
+		Name:     "openai-apikey",
+		Platform: PlatformOpenAI,
+		Type:     AccountTypeAPIKey,
+		Credentials: map[string]any{
+			"api_key":  "test-api-key",
+			"base_url": "https://image-upstream.example/v1/",
+		},
+	}
+
+	result, err := svc.ForwardImages(context.Background(), c, account, body.Bytes(), parsed, "")
+	require.NoError(t, err)
+	require.NotNil(t, result)
+	require.Equal(t, 1, result.ImageCount)
+
+	upstream, ok := svc.httpUpstream.(*httpUpstreamRecorder)
+	require.True(t, ok)
+	require.NotNil(t, upstream.lastReq)
+	require.Equal(t, "https://image-upstream.example/v1/images/edits", upstream.lastReq.URL.String())
+	require.Equal(t, "Bearer test-api-key", upstream.lastReq.Header.Get("Authorization"))
+	require.Contains(t, upstream.lastReq.Header.Get("Content-Type"), "multipart/form-data")
+	require.Contains(t, string(upstream.lastBody), `name="model"`)
+	require.Contains(t, string(upstream.lastBody), "gpt-image-2")
+	require.Equal(t, http.StatusOK, rec.Code)
+	require.Equal(t, "ZWRpdGVk", gjson.Get(rec.Body.String(), "data.0.b64_json").String())
+}
+
 func TestOpenAIGatewayServiceForwardImages_OAuthStreamingTransformsEvents(t *testing.T) {
 	gin.SetMode(gin.TestMode)
 	body := []byte(`{"model":"gpt-image-2","prompt":"draw a cat","stream":true,"response_format":"url"}`)