diff --git a/backend/internal/service/grok_media.go b/backend/internal/service/grok_media.go
index f8b7ff3e83..09d70eb0bd 100644
--- a/backend/internal/service/grok_media.go
+++ b/backend/internal/service/grok_media.go
@@ -433,9 +433,9 @@ func normalizeGrokMediaForwardBody(endpoint GrokMediaEndpoint, body []byte, cont
 	if !endpoint.RequiresRequestBody() || !gjson.ValidBytes(body) {
 		return body, contentType, nil
 	}
-	model := strings.TrimSpace(gjson.GetBytes(body, "model").String())
-	upstreamModel := normalizeGrokMediaModelForEndpoint(endpoint, model)
-	if upstreamModel == "" || upstreamModel == model {
+	info := ParseGrokMediaRequest(contentType, body)
+	upstreamModel := normalizeGrokMediaModelForEndpoint(endpoint, info.Model, info.HasInputImage())
+	if upstreamModel == "" || upstreamModel == info.Model {
 		return body, contentType, nil
 	}
 	out, err := sjson.SetBytes(body, "model", upstreamModel)
@@ -445,13 +445,21 @@ func normalizeGrokMediaForwardBody(endpoint GrokMediaEndpoint, body []byte, cont
 	return out, contentType, nil
 }
 
-func normalizeGrokMediaModelForEndpoint(endpoint GrokMediaEndpoint, model string) string {
+func (r GrokMediaRequestInfo) HasInputImage() bool {
+	return len(r.InputImageURLs) > 0 || len(r.Uploads) > 0
+}
+
+func normalizeGrokMediaModelForEndpoint(endpoint GrokMediaEndpoint, model string, hasInputImage bool) string {
 	model = strings.TrimSpace(model)
 	switch endpoint {
 	case GrokMediaEndpointImagesGenerations, GrokMediaEndpointImagesEdits:
 		if model == "grok-imagine" {
 			return "grok-imagine-image-quality"
 		}
+	case GrokMediaEndpointVideosGenerations:
+		if model == "grok-imagine-video-1.5" && !hasInputImage {
+			return "grok-imagine-video"
+		}
 	}
 	return model
 }
diff --git a/backend/internal/service/openai_gateway_grok_test.go b/backend/internal/service/openai_gateway_grok_test.go
index d012ab533a..f6aa4b6cd1 100644
--- a/backend/internal/service/openai_gateway_grok_test.go
+++ b/backend/internal/service/openai_gateway_grok_test.go
@@ -203,21 +203,24 @@ func TestParseGrokMediaRequestBuildsMultipartModerationBody(t *testing.T) {
 
 func TestNormalizeGrokMediaModelForEndpoint(t *testing.T) {
 	tests := []struct {
-		name     string
-		endpoint GrokMediaEndpoint
-		model    string
-		want     string
+		name          string
+		endpoint      GrokMediaEndpoint
+		model         string
+		hasInputImage bool
+		want          string
 	}{
 		{name: "image generation alias", endpoint: GrokMediaEndpointImagesGenerations, model: "grok-imagine", want: "grok-imagine-image-quality"},
 		{name: "image edit alias", endpoint: GrokMediaEndpointImagesEdits, model: "grok-imagine", want: "grok-imagine-image-quality"},
 		{name: "image quality passthrough", endpoint: GrokMediaEndpointImagesGenerations, model: "grok-imagine-image-quality", want: "grok-imagine-image-quality"},
 		{name: "image fast passthrough", endpoint: GrokMediaEndpointImagesGenerations, model: "grok-imagine-image", want: "grok-imagine-image"},
 		{name: "video passthrough", endpoint: GrokMediaEndpointVideosGenerations, model: "grok-imagine-video", want: "grok-imagine-video"},
+		{name: "video 1.5 text-only fallback", endpoint: GrokMediaEndpointVideosGenerations, model: "grok-imagine-video-1.5", want: "grok-imagine-video"},
+		{name: "video 1.5 image-to-video passthrough", endpoint: GrokMediaEndpointVideosGenerations, model: "grok-imagine-video-1.5", hasInputImage: true, want: "grok-imagine-video-1.5"},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			require.Equal(t, tt.want, normalizeGrokMediaModelForEndpoint(tt.endpoint, tt.model))
+			require.Equal(t, tt.want, normalizeGrokMediaModelForEndpoint(tt.endpoint, tt.model, tt.hasInputImage))
 		})
 	}
 }
@@ -355,13 +358,52 @@ func TestForwardGrokMediaVideoGenerationReturnsUsageAndResponseID(t *testing.T)
 	result, err := svc.ForwardGrokMedia(context.Background(), c, account, GrokMediaEndpointVideosGenerations, "", body, "application/json")
 	require.NoError(t, err)
 	require.Equal(t, "https://xai.test/v1/videos/generations", upstream.lastReq.URL.String())
+	require.JSONEq(t, `{"model":"grok-imagine-video","prompt":"waves"}`, string(upstream.lastBody))
 	require.Equal(t, "video-request-123", result.ResponseID)
-	require.Equal(t, "grok-imagine-video-1.5", result.BillingModel)
+	require.Equal(t, "grok-imagine-video", result.BillingModel)
 	require.Equal(t, 3, result.Usage.InputTokens)
 	require.Equal(t, 4, result.Usage.OutputTokens)
 	require.Equal(t, 1, result.ImageCount)
 }
 
+func TestForwardGrokMediaVideoGenerationPreservesImageToVideoModel(t *testing.T) {
+	t.Setenv(xai.EnvAllowUnsafeURLOverrides, "true")
+	gin.SetMode(gin.TestMode)
+
+	recorder := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(recorder)
+	body := []byte(`{"model":"grok-imagine-video-1.5","prompt":"animate","image":{"image_url":"data:image/png;base64,aW1n"}}`)
+	c.Request = httptest.NewRequest(http.MethodPost, "/v1/videos/generations", bytes.NewReader(body))
+	c.Request.Header.Set("Content-Type", "application/json")
+
+	account := &Account{
+		ID:          63,
+		Name:        "grok",
+		Platform:    PlatformGrok,
+		Type:        AccountTypeAPIKey,
+		Concurrency: 1,
+		Credentials: map[string]any{
+			"api_key":  "api-key",
+			"base_url": "https://xai.test/v1",
+		},
+	}
+	upstream := &httpUpstreamRecorder{resp: &http.Response{
+		StatusCode: http.StatusOK,
+		Header: http.Header{
+			"Content-Type": []string{"application/json"},
+		},
+		Body: io.NopCloser(strings.NewReader(`{"request_id":"video-request-456"}`)),
+	}}
+	svc := &OpenAIGatewayService{httpUpstream: upstream}
+
+	result, err := svc.ForwardGrokMedia(context.Background(), c, account, GrokMediaEndpointVideosGenerations, "", body, "application/json")
+	require.NoError(t, err)
+	require.Equal(t, "https://xai.test/v1/videos/generations", upstream.lastReq.URL.String())
+	require.JSONEq(t, `{"model":"grok-imagine-video-1.5","prompt":"animate","image":{"image_url":"data:image/png;base64,aW1n"}}`, string(upstream.lastBody))
+	require.Equal(t, "video-request-456", result.ResponseID)
+	require.Equal(t, "grok-imagine-video-1.5", result.BillingModel)
+}
+
 func TestForwardGrokMediaVideoStatusUsesGETWithoutBody(t *testing.T) {
 	t.Setenv(xai.EnvAllowUnsafeURLOverrides, "true")
 	gin.SetMode(gin.TestMode)