diff --git a/controller/metaproxy_provision.go b/controller/metaproxy_provision.go
index 36decc712dbe..54ebf8f82937 100644
--- a/controller/metaproxy_provision.go
+++ b/controller/metaproxy_provision.go
@@ -11,6 +11,7 @@ import (
 
 	"github.com/QuantumNous/new-api/common"
 	"github.com/QuantumNous/new-api/model"
+	"github.com/QuantumNous/new-api/setting/billing_setting"
 	"github.com/gin-gonic/gin"
 )
 
@@ -38,6 +39,8 @@ type metaproxyProvisionOptionsRequest struct {
 	ModelRatio       string `json:"model_ratio"`
 	CompletionRatio  string `json:"completion_ratio"`
 	CacheRatio       string `json:"cache_ratio"`
+	ModelBillingMode string `json:"model_billing_mode"`
+	ModelBillingExpr string `json:"model_billing_expr"`
 	GroupRatio       string `json:"group_ratio"`
 	UserUsableGroups string `json:"user_usable_groups"`
 }
@@ -78,6 +81,22 @@ func parseUserUsableGroups(raw string) (map[string]string, error) {
 	return values, nil
 }
 
+func parseStringMap(name, raw string) (map[string]string, error) {
+	values := make(map[string]string)
+	if strings.TrimSpace(raw) == "" {
+		return values, nil
+	}
+	if err := common.Unmarshal([]byte(raw), &values); err != nil {
+		return nil, fmt.Errorf("%s must be a JSON object of strings: %w", name, err)
+	}
+	for key, value := range values {
+		if strings.TrimSpace(key) == "" || strings.TrimSpace(value) == "" {
+			return nil, fmt.Errorf("%s contains an empty model or value", name)
+		}
+	}
+	return values, nil
+}
+
 func validateOptionalJSONObject(name, raw string) error {
 	if raw == "" {
 		return nil
@@ -152,6 +171,31 @@ func validateMetaproxyProvisionRequest(
 	if _, err := parseRatioMap("CacheRatio", request.Options.CacheRatio, true); err != nil {
 		return err
 	}
+	billingModes, err := parseStringMap("ModelBillingMode", request.Options.ModelBillingMode)
+	if err != nil {
+		return err
+	}
+	billingExprs, err := parseStringMap("ModelBillingExpr", request.Options.ModelBillingExpr)
+	if err != nil {
+		return err
+	}
+	for modelName, mode := range billingModes {
+		if mode != billing_setting.BillingModeTieredExpr {
+			return fmt.Errorf("ModelBillingMode contains unsupported mode %q for %q", mode, modelName)
+		}
+		expr, ok := billingExprs[modelName]
+		if !ok {
+			return fmt.Errorf("model %q uses tiered_expr but is missing from ModelBillingExpr", modelName)
+		}
+		if err := billing_setting.SmokeTestExpr(expr); err != nil {
+			return fmt.Errorf("ModelBillingExpr for %q is invalid: %w", modelName, err)
+		}
+	}
+	for modelName := range billingExprs {
+		if _, ok := billingModes[modelName]; !ok {
+			return fmt.Errorf("model %q has ModelBillingExpr but is missing from ModelBillingMode", modelName)
+		}
+	}
 	groupRatios, err := parseRatioMap("GroupRatio", request.Options.GroupRatio, false)
 	if err != nil {
 		return err
@@ -220,10 +264,11 @@ func validateMetaproxyProvisionRequest(
 		}
 		for _, modelName := range models {
 			ratio, priced := modelRatios[modelName]
-			if !priced {
-				return fmt.Errorf("enabled model %q in an offered group is missing from ModelRatio", modelName)
+			_, expressionPriced := billingModes[modelName]
+			if !priced && !expressionPriced {
+				return fmt.Errorf("enabled model %q in an offered group is missing from ModelRatio and ModelBillingMode", modelName)
 			}
-			if ratio == 0 {
+			if priced && ratio == 0 && !expressionPriced {
 				return fmt.Errorf("enabled model %q in an offered group must have a positive ModelRatio", modelName)
 			}
 		}
@@ -232,6 +277,12 @@ func validateMetaproxyProvisionRequest(
 }
 
 func toMetaproxyProvisionConfig(request metaproxyProvisionRequest) model.MetaproxyProvisionConfig {
+	if strings.TrimSpace(request.Options.ModelBillingMode) == "" {
+		request.Options.ModelBillingMode = "{}"
+	}
+	if strings.TrimSpace(request.Options.ModelBillingExpr) == "" {
+		request.Options.ModelBillingExpr = "{}"
+	}
 	channels := make([]model.MetaproxyProvisionChannel, 0, len(request.Channels))
 	for _, channel := range request.Channels {
 		models, _ := commaValues(channel.Models)
@@ -259,6 +310,8 @@ func toMetaproxyProvisionConfig(request metaproxyProvisionRequest) model.Metapro
 			ModelRatio:       request.Options.ModelRatio,
 			CompletionRatio:  request.Options.CompletionRatio,
 			CacheRatio:       request.Options.CacheRatio,
+			ModelBillingMode: request.Options.ModelBillingMode,
+			ModelBillingExpr: request.Options.ModelBillingExpr,
 			GroupRatio:       request.Options.GroupRatio,
 			UserUsableGroups: request.Options.UserUsableGroups,
 		},
diff --git a/controller/metaproxy_provision_test.go b/controller/metaproxy_provision_test.go
index ca4eb47eccab..adfd0f6af7f4 100644
--- a/controller/metaproxy_provision_test.go
+++ b/controller/metaproxy_provision_test.go
@@ -34,17 +34,56 @@ func validMetaproxyProvisionRequest() metaproxyProvisionRequest {
 			ModelRatio:       `{"model-one":1}`,
 			CompletionRatio:  `{"model-one":2}`,
 			CacheRatio:       `{"model-one":0.1}`,
+			ModelBillingMode: `{}`,
+			ModelBillingExpr: `{}`,
 			GroupRatio:       `{"standard":1}`,
 			UserUsableGroups: `{"standard":"Standard"}`,
 		},
 	}
 }
 
+func TestValidateMetaproxyProvisionRequestAcceptsExpressionPricedModel(t *testing.T) {
+	request := validMetaproxyProvisionRequest()
+	request.Options.ModelRatio = `{}`
+	request.Options.ModelBillingMode = `{"model-one":"tiered_expr"}`
+	request.Options.ModelBillingExpr = `{"model-one":"(param(\"n\") == nil ? 1 : param(\"n\")) * (param(\"resolution\") == \"1k\" ? tier(\"1k\", 200000) : tier(\"2k\", 300000))"}`
+	require.NoError(t, validateMetaproxyProvisionRequest(request, request.Digest, "none"))
+}
+
+func TestValidateMetaproxyProvisionRequestRejectsInvalidBillingExpression(t *testing.T) {
+	request := validMetaproxyProvisionRequest()
+	request.Options.ModelRatio = `{}`
+	request.Options.ModelBillingMode = `{"model-one":"tiered_expr"}`
+	request.Options.ModelBillingExpr = `{"model-one":"tier(\"broken\", -1"}`
+	err := validateMetaproxyProvisionRequest(request, request.Digest, "none")
+	require.ErrorContains(t, err, "ModelBillingExpr")
+}
+
+func TestValidateMetaproxyProvisionRequestRejectsExpressionModeWithoutExpression(t *testing.T) {
+	request := validMetaproxyProvisionRequest()
+	request.Options.ModelRatio = `{}`
+	request.Options.ModelBillingMode = `{"model-one":"tiered_expr"}`
+	err := validateMetaproxyProvisionRequest(request, request.Digest, "none")
+	require.ErrorContains(t, err, "model-one")
+	require.ErrorContains(t, err, "ModelBillingExpr")
+}
+
 func TestValidateMetaproxyProvisionRequestAcceptsCompleteConfig(t *testing.T) {
 	request := validMetaproxyProvisionRequest()
 	require.NoError(t, validateMetaproxyProvisionRequest(request, request.Digest, "none"))
 }
 
+func TestValidateMetaproxyProvisionRequestAcceptsLegacyRequestWithoutBillingExpressions(t *testing.T) {
+	request := validMetaproxyProvisionRequest()
+	request.Options.ModelBillingMode = ""
+	request.Options.ModelBillingExpr = ""
+	require.NoError(t, validateMetaproxyProvisionRequest(request, request.Digest, "none"))
+
+	config := toMetaproxyProvisionConfig(request)
+	require.Equal(t, "{}", config.Options.ModelBillingMode)
+	require.Equal(t, "{}", config.Options.ModelBillingExpr)
+}
+
 func TestValidateMetaproxyProvisionRequestRejectsMismatchedIdempotencyKey(t *testing.T) {
 	request := validMetaproxyProvisionRequest()
 	err := validateMetaproxyProvisionRequest(
@@ -122,6 +161,17 @@ func TestToMetaproxyProvisionConfigStoresNormalizedLists(t *testing.T) {
 	require.Equal(t, "standard,archive", config.Channels[0].Group)
 }
 
+func TestToMetaproxyProvisionConfigNormalizesWhitespaceBillingOptions(t *testing.T) {
+	request := validMetaproxyProvisionRequest()
+	request.Options.ModelBillingMode = " \t\n"
+	request.Options.ModelBillingExpr = "\r\n"
+
+	config := toMetaproxyProvisionConfig(request)
+
+	require.Equal(t, "{}", config.Options.ModelBillingMode)
+	require.Equal(t, "{}", config.Options.ModelBillingExpr)
+}
+
 func TestApplyMetaproxyProvisionRequiresMemoryCache(t *testing.T) {
 	previous := common.MemoryCacheEnabled
 	common.MemoryCacheEnabled = false
diff --git a/dto/openai_image.go b/dto/openai_image.go
index 275fd5559080..bd6f514cd32e 100644
--- a/dto/openai_image.go
+++ b/dto/openai_image.go
@@ -20,6 +20,8 @@ type ImageRequest struct {
 	Prompt            string          `json:"prompt" binding:"required"`
 	N                 *uint           `json:"n,omitempty"`
 	Size              string          `json:"size,omitempty"`
+	Resolution        string          `json:"resolution,omitempty"`
+	AspectRatio       string          `json:"aspect_ratio,omitempty"`
 	Quality           string          `json:"quality,omitempty"`
 	ResponseFormat    string          `json:"response_format,omitempty"`
 	Style             json.RawMessage `json:"style,omitempty"`
diff --git a/dto/openai_image_test.go b/dto/openai_image_test.go
new file mode 100644
index 000000000000..c02bf1f8cfcc
--- /dev/null
+++ b/dto/openai_image_test.go
@@ -0,0 +1,20 @@
+package dto
+
+import (
+	"testing"
+
+	"github.com/QuantumNous/new-api/common"
+	"github.com/stretchr/testify/require"
+)
+
+func TestImageRequestPreservesProviderResolutionFields(t *testing.T) {
+	raw := []byte(`{"model":"grok-imagine-image","prompt":"test","resolution":"2k","aspect_ratio":"16:9"}`)
+	var request ImageRequest
+	require.NoError(t, common.Unmarshal(raw, &request))
+	require.Equal(t, "2k", request.Resolution)
+	require.Equal(t, "16:9", request.AspectRatio)
+
+	encoded, err := common.Marshal(request)
+	require.NoError(t, err)
+	require.JSONEq(t, string(raw), string(encoded))
+}
diff --git a/model/metaproxy_provision.go b/model/metaproxy_provision.go
index 5f14c5ee0ba0..ed6a9785c7dc 100644
--- a/model/metaproxy_provision.go
+++ b/model/metaproxy_provision.go
@@ -45,6 +45,8 @@ type MetaproxyProvisionOptions struct {
 	ModelRatio       string `json:"model_ratio"`
 	CompletionRatio  string `json:"completion_ratio"`
 	CacheRatio       string `json:"cache_ratio"`
+	ModelBillingMode string `json:"model_billing_mode"`
+	ModelBillingExpr string `json:"model_billing_expr"`
 	GroupRatio       string `json:"group_ratio"`
 	UserUsableGroups string `json:"user_usable_groups"`
 }
@@ -54,6 +56,8 @@ func (options MetaproxyProvisionOptions) orderedValues() []Option {
 		{Key: "ModelRatio", Value: options.ModelRatio},
 		{Key: "CompletionRatio", Value: options.CompletionRatio},
 		{Key: "CacheRatio", Value: options.CacheRatio},
+		{Key: "billing_setting.billing_mode", Value: options.ModelBillingMode},
+		{Key: "billing_setting.billing_expr", Value: options.ModelBillingExpr},
 		{Key: "GroupRatio", Value: options.GroupRatio},
 		{Key: "UserUsableGroups", Value: options.UserUsableGroups},
 	}
diff --git a/model/metaproxy_provision_test.go b/model/metaproxy_provision_test.go
index 9fe410d7aead..610959dc6f0a 100644
--- a/model/metaproxy_provision_test.go
+++ b/model/metaproxy_provision_test.go
@@ -85,6 +85,8 @@ func seedProvisionState(t *testing.T, db *gorm.DB) Channel {
 		{Key: "ModelRatio", Value: `{"old-model":1}`},
 		{Key: "CompletionRatio", Value: `{"old-model":2}`},
 		{Key: "CacheRatio", Value: `{}`},
+		{Key: "billing_setting.billing_mode", Value: `{}`},
+		{Key: "billing_setting.billing_expr", Value: `{}`},
 		{Key: "GroupRatio", Value: `{"standard":1}`},
 		{Key: "UserUsableGroups", Value: `{"default":"standard"}`},
 	}).Error)
@@ -102,6 +104,8 @@ func desiredProvisionConfig() MetaproxyProvisionConfig {
 			ModelRatio:       `{"new-model":1.5}`,
 			CompletionRatio:  `{"new-model":3}`,
 			CacheRatio:       `{"new-model":0.1}`,
+			ModelBillingMode: `{"image-model":"tiered_expr"}`,
+			ModelBillingExpr: `{"image-model":"tier(\"base\", 200000)"}`,
 			GroupRatio:       `{"standard":1}`,
 			UserUsableGroups: `{"default":"standard"}`,
 		},
@@ -140,6 +144,8 @@ func TestApplyMetaproxyProvisionReplacesManagedStateAtomically(t *testing.T) {
 	require.Equal(t, desiredProvisionConfig().Digest, got[MetaproxyProvisionDigestOption])
 	require.Equal(t, desiredProvisionConfig().Revision, got[MetaproxyProvisionRevisionOption])
 	require.Equal(t, `{"new-model":1.5}`, got["ModelRatio"])
+	require.Equal(t, `{"image-model":"tiered_expr"}`, got["billing_setting.billing_mode"])
+	require.Equal(t, `{"image-model":"tier(\"base\", 200000)"}`, got["billing_setting.billing_expr"])
 
 	common.OptionMapRWMutex.RLock()
 	require.Equal(t, "old-digest", common.OptionMap[MetaproxyProvisionDigestOption])
diff --git a/relay/channel/minimax/adaptor_test.go b/relay/channel/minimax/adaptor_test.go
index 46d57c11ff72..342eec861161 100644
--- a/relay/channel/minimax/adaptor_test.go
+++ b/relay/channel/minimax/adaptor_test.go
@@ -84,6 +84,22 @@ func TestConvertImageRequest(t *testing.T) {
 	}
 }
 
+func TestConvertImageRequestPreservesExplicitAspectRatio(t *testing.T) {
+	t.Parallel()
+
+	request := dto.ImageRequest{
+		Model:       "image-01",
+		Prompt:      "a red fox in snowfall",
+		Size:        "1536x1024",
+		AspectRatio: "16:9",
+	}
+
+	got := oaiImage2MiniMaxImageRequest(request)
+	if got.AspectRatio != "16:9" {
+		t.Fatalf("aspect_ratio = %q, want %q", got.AspectRatio, "16:9")
+	}
+}
+
 func TestDoResponseForImageGeneration(t *testing.T) {
 	t.Parallel()
 
diff --git a/relay/channel/minimax/image.go b/relay/channel/minimax/image.go
index 9b316bdc8230..9d851fefa92f 100644
--- a/relay/channel/minimax/image.go
+++ b/relay/channel/minimax/image.go
@@ -69,6 +69,9 @@ func oaiImage2MiniMaxImageRequest(request dto.ImageRequest) MiniMaxImageRequest
 }
 
 func aspectRatioFromImageRequest(request dto.ImageRequest) string {
+	if request.AspectRatio != "" {
+		return request.AspectRatio
+	}
 	if raw, ok := request.Extra["aspect_ratio"]; ok {
 		var aspectRatio string
 		if err := common.Unmarshal(raw, &aspectRatio); err == nil && aspectRatio != "" {