diff --git a/backend/internal/handler/composite_platform_test.go b/backend/internal/handler/composite_platform_test.go
index 30f837f3c5..a879f9ffe5 100644
--- a/backend/internal/handler/composite_platform_test.go
+++ b/backend/internal/handler/composite_platform_test.go
@@ -22,16 +22,19 @@ func TestCompositeTargetPlatformAllowedResolvesKnownAllowedModel(t *testing.T) {
 	require.Equal(t, service.PlatformOpenAI, platform)
 }
 
-func TestOpenAICompatibleMessagesTargetAllowsCompositeGrokModel(t *testing.T) {
+func TestOpenAICompatibleTextTargetAllowsCompositeGrokModel(t *testing.T) {
 	gin.SetMode(gin.TestMode)
-	c, _ := gin.CreateTestContext(httptest.NewRecorder())
-	c.Request = httptest.NewRequest("POST", "/v1/messages", nil)
-	apiKey := &service.APIKey{Group: &service.Group{Platform: service.PlatformComposite}}
 
-	require.True(t, openAICompatibleMessagesTargetAllowed(c, apiKey, "grok-4.3"))
-	platform, ok := service.ResolvedTargetPlatformFromContext(c.Request.Context())
-	require.True(t, ok)
-	require.Equal(t, service.PlatformGrok, platform)
+	for _, path := range []string{"/v1/messages", "/v1/chat/completions"} {
+		c, _ := gin.CreateTestContext(httptest.NewRecorder())
+		c.Request = httptest.NewRequest("POST", path, nil)
+		apiKey := &service.APIKey{Group: &service.Group{Platform: service.PlatformComposite}}
+
+		require.True(t, openAICompatibleTextTargetAllowed(c, apiKey, "grok-4.3"), "path=%s", path)
+		platform, ok := service.ResolvedTargetPlatformFromContext(c.Request.Context())
+		require.True(t, ok, "path=%s", path)
+		require.Equal(t, service.PlatformGrok, platform, "path=%s", path)
+	}
 }
 
 func TestCompositeTargetPlatformAllowedRejectsWrongOrUnknownModel(t *testing.T) {
diff --git a/backend/internal/handler/openai_chat_completions.go b/backend/internal/handler/openai_chat_completions.go
index 8ccc4fb49e..7477057113 100644
--- a/backend/internal/handler/openai_chat_completions.go
+++ b/backend/internal/handler/openai_chat_completions.go
@@ -76,7 +76,7 @@ func (h *OpenAIGatewayHandler) ChatCompletions(c *gin.Context) {
 	}
 	reqModel := modelResult.String()
 	ensureCompositeTargetPlatform(c, apiKey, reqModel)
-	if !compositeTargetPlatformAllowed(c, apiKey, reqModel, service.PlatformOpenAI) {
+	if !openAICompatibleTextTargetAllowed(c, apiKey, reqModel) {
 		h.errorResponse(c, http.StatusBadRequest, "invalid_request_error", "Model is not supported by this OpenAI-compatible endpoint for composite groups")
 		return
 	}
diff --git a/backend/internal/handler/openai_gateway_handler.go b/backend/internal/handler/openai_gateway_handler.go
index f623f3dfff..1e5949f36f 100644
--- a/backend/internal/handler/openai_gateway_handler.go
+++ b/backend/internal/handler/openai_gateway_handler.go
@@ -147,7 +147,7 @@ func allowOpenAICompatibleMessagesDispatch(apiKey *service.APIKey) bool {
 	return apiKey.Group.AllowMessagesDispatch
 }
 
-func openAICompatibleMessagesTargetAllowed(c *gin.Context, apiKey *service.APIKey, model string) bool {
+func openAICompatibleTextTargetAllowed(c *gin.Context, apiKey *service.APIKey, model string) bool {
 	return compositeTargetPlatformAllowed(c, apiKey, model, service.PlatformOpenAI, service.PlatformGrok)
 }
 
@@ -877,7 +877,7 @@ func (h *OpenAIGatewayHandler) Messages(c *gin.Context) {
 	}
 	reqModel := modelResult.String()
 	ensureCompositeTargetPlatform(c, apiKey, reqModel)
-	if !openAICompatibleMessagesTargetAllowed(c, apiKey, reqModel) {
+	if !openAICompatibleTextTargetAllowed(c, apiKey, reqModel) {
 		h.anthropicErrorResponse(c, http.StatusBadRequest, "invalid_request_error", "Model is not supported by this OpenAI-compatible endpoint for composite groups")
 		return
 	}
diff --git a/backend/internal/server/routes/gateway_test.go b/backend/internal/server/routes/gateway_test.go
index fbf56959f3..c3e871a803 100644
--- a/backend/internal/server/routes/gateway_test.go
+++ b/backend/internal/server/routes/gateway_test.go
@@ -208,6 +208,23 @@ func TestGatewayRoutesCompositeMessagesWithGrokModelUsesOpenAIGateway(t *testing
 	require.NotContains(t, w.Body.String(), "composite groups")
 }
 
+func TestGatewayRoutesCompositeChatCompletionsWithGrokModelUsesOpenAIGateway(t *testing.T) {
+	router := newGatewayRoutesTestRouter(service.PlatformComposite)
+
+	for _, path := range []string{"/v1/chat/completions", "/chat/completions"} {
+		req := httptest.NewRequest(http.MethodPost, path, strings.NewReader(`{"model":"grok-4.3","messages":[{"role":"user","content":"hi"}]}`))
+		req.Header.Set("Content-Type", "application/json")
+		w := httptest.NewRecorder()
+
+		router.ServeHTTP(w, req)
+
+		require.NotEqual(t, http.StatusNotFound, w.Code, "path=%s", path)
+		require.NotContains(t, w.Body.String(), "not supported")
+		require.NotContains(t, w.Body.String(), "OpenAI-compatible endpoint")
+		require.NotContains(t, w.Body.String(), "composite groups")
+	}
+}
+
 func TestGatewayRoutesNonGrokVideosAreRejectedAtPlatformGate(t *testing.T) {
 	router := newGatewayRoutesTestRouter(service.PlatformOpenAI)