fix(billing): settle tiered retries with final group (#6518)

controller/relay.go

@@ -199,6 +199,10 @@ func Relay(c *gin.Context, relayFormat types.RelayFormat) {
 			newAPIError = channelErr
 			break
 		}
+		if billingErr := service.PrepareTieredBillingForSelectedGroup(c, relayInfo); billingErr != nil {
+			newAPIError = billingErr
+			break
+		}
 
 		addUsedChannel(c, channel.Id)
 		bodyStorage, bodyErr := common.GetBodyStorage(c)

pkg/billingexpr/expr.md

@@ -159,7 +159,7 @@ When a request arrives and the model uses `tiered_expr` billing:
 2. Builds `RequestInput` (headers + body) for `param()` / `header()` functions
 3. Runs expression with estimated tokens: `RunExprWithRequest(expr, {P, C}, requestInput)`
 4. Converts output to quota: `rawCost / 1,000,000 * QuotaPerUnit`
-5. Creates `BillingSnapshot` (frozen state for settlement) and stores on `RelayInfo`
+5. Creates `BillingSnapshot` and stores it on `RelayInfo`. Expression and request state stay frozen for settlement. An auto-group retry refreshes group-dependent fields from the selected group before the next upstream attempt. If a free initial group skipped pre-consume and the retry selects a paid group, the billing session is created before that attempt. If an existing session moves to a more expensive group, its reservation is raised to that group's estimate before sending; cheaper groups are refunded only after actual usage is settled.
 
 ### 4. Settlement (Actual Billing)
 
@@ -173,7 +173,7 @@ After the upstream response returns with actual token usage:
    - For Claude-format APIs (input_tokens is text-only): no adjustment needed
 
 2. `TryTieredSettle(relayInfo, params)`:
-   - Uses the frozen `BillingSnapshot` from pre-consume
+   - Uses the captured `BillingSnapshot`, whose group-dependent fields have been refreshed from the final selected group
    - Re-runs the expression with actual token counts
    - Converts via `quotaConversion()` (version-dispatched)
    - Returns actual quota

pkg/billingexpr/types.go

@@ -36,8 +36,10 @@ type TraceResult struct {
 	Cost        float64 `json:"cost"`
 }
 
-// BillingSnapshot captures the billing rule state frozen at pre-consume time.
+// BillingSnapshot captures billing state at pre-consume time. Expression and
-// It is fully serializable and contains no compiled program pointers.
+// request fields stay frozen; group-dependent fields are refreshed before an
+// auto-group retry and settlement. It is fully serializable and contains no
+// compiled program pointers.
 type BillingSnapshot struct {
 	BillingMode               string  `json:"billing_mode"`
 	ModelName                 string  `json:"model_name"`

relay/common/relay_info.go

@@ -122,7 +122,7 @@ type RelayInfo struct {
 	// 必须在提交前锁定全额。
 	ForcePreConsume bool
 	// Billing 是计费会话，封装了预扣费/结算/退款的统一生命周期。
-	// 免费模型时为 nil。
+	// 初始免费组可为 nil；若 auto 重试切换到付费组，会在发送前创建。
 	Billing BillingSettler
 	// BillingSource indicates whether this request is billed from wallet quota or subscription.
 	// "" or "wallet" => wallet; "subscription" => subscription
@@ -163,8 +163,9 @@ type RelayInfo struct {
 	// It is surfaced onto the consume/task log's admin_info for auditing.
 	QuotaClamp *common.QuotaClamp
 
-	// TieredBillingSnapshot is a frozen snapshot of tiered billing rules
+	// TieredBillingSnapshot captures tiered billing rules at pre-consume time.
-	// captured at pre-consume time. Non-nil only when billing mode is "tiered_expr".
+	// Auto-group retries refresh its group-dependent fields before each attempt
+	// and again before settlement. Non-nil only when billing mode is "tiered_expr".
 	TieredBillingSnapshot *billingexpr.BillingSnapshot
 	BillingRequestInput   *billingexpr.RequestInput
 

service/tiered_settle.go

@@ -1,9 +1,13 @@
 package service
 
 import (
+	"net/http"
+
 	"github.com/QuantumNous/new-api/pkg/billingexpr"
 	relaycommon "github.com/QuantumNous/new-api/relay/common"
 	"github.com/QuantumNous/new-api/relaykit/dto"
+	"github.com/QuantumNous/new-api/relaykit/types"
+	"github.com/gin-gonic/gin"
 )
 
 // TieredResultWrapper wraps billingexpr.TieredResult for use at the service layer.
@@ -90,8 +94,60 @@ func BuildTieredTokenParams(usage *dto.Usage, isClaudeUsageSemantic bool, usedVa
 	}
 }
 
+func refreshTieredBillingGroup(relayInfo *relaycommon.RelayInfo) (*billingexpr.BillingSnapshot, error) {
+	if relayInfo == nil {
+		return nil, nil
+	}
+	snap := relayInfo.TieredBillingSnapshot
+	if snap == nil || snap.BillingMode != "tiered_expr" {
+		return nil, nil
+	}
+
+	groupRatio := relayInfo.PriceData.GroupRatioInfo.GroupRatio
+	if snap.GroupRatio == groupRatio {
+		return snap, nil
+	}
+
+	estimatedQuotaAfterGroup := snap.EstimatedQuotaBeforeGroup * groupRatio
+	estimatedQuota, err := billingexpr.QuotaRoundStrict(estimatedQuotaAfterGroup)
+	if err != nil {
+		return nil, err
+	}
+	snap.GroupRatio = groupRatio
+	snap.EstimatedQuotaAfterGroup = estimatedQuota
+	return snap, nil
+}
+
+// PrepareTieredBillingForSelectedGroup refreshes routing-dependent billing
+// state before an upstream attempt. An existing session reserves any higher
+// estimate before sending. If the initial group was free and skipped
+// pre-consume, switching to a paid group creates the session at that point.
+func PrepareTieredBillingForSelectedGroup(c *gin.Context, relayInfo *relaycommon.RelayInfo) *types.NewAPIError {
+	snap, err := refreshTieredBillingGroup(relayInfo)
+	if err != nil {
+		return types.NewErrorWithStatusCode(
+			err,
+			types.ErrorCodeModelPriceError,
+			http.StatusBadRequest,
+			types.ErrOptionWithSkipRetry(),
+		)
+	}
+	if snap == nil || snap.GroupRatio == 0 {
+		return nil
+	}
+
+	if relayInfo.Billing == nil {
+		return PreConsumeBilling(c, snap.EstimatedQuotaAfterGroup, relayInfo)
+	}
+	if err := relayInfo.Billing.Reserve(snap.EstimatedQuotaAfterGroup); err != nil {
+		return types.NewError(err, types.ErrorCodeUpdateDataError, types.ErrOptionWithSkipRetry())
+	}
+	relayInfo.FinalPreConsumedQuota = relayInfo.Billing.GetPreConsumedQuota()
+	return nil
+}
+
 // TryTieredSettle checks if the request uses tiered_expr billing and, if so,
-// computes the actual quota using the frozen BillingSnapshot. Returns:
+// computes the actual quota using the captured BillingSnapshot. Returns:
 //   - ok=true, quota, result  when tiered billing applies
 //   - ok=false, 0, nil        when it doesn't (caller should fall through to existing logic)
 func TryTieredSettle(relayInfo *relaycommon.RelayInfo, params billingexpr.TokenParams) (ok bool, quota int, result *billingexpr.TieredResult) {

service/tiered_settle_test.go

@@ -5,10 +5,15 @@ import (
 	"math/rand"
 	"testing"
 
+	"github.com/QuantumNous/new-api/model"
 	"github.com/QuantumNous/new-api/pkg/billingexpr"
 	relaycommon "github.com/QuantumNous/new-api/relay/common"
 	"github.com/QuantumNous/new-api/relaykit/dto"
+	"github.com/QuantumNous/new-api/types"
+	"github.com/gin-gonic/gin"
 	"github.com/shopspring/decimal"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 // Claude Sonnet-style tiered expression: standard vs long-context
@@ -309,6 +314,139 @@ func TestTryTieredSettle_NoRequestInput_FallsBackToDefault(t *testing.T) {
 // Group ratio tests
 // ---------------------------------------------------------------------------
 
+type recordingBillingSettler struct {
+	preConsumedQuota int
+	reserveTargets   []int
+}
+
+func (*recordingBillingSettler) Settle(int) error { return nil }
+
+func (*recordingBillingSettler) Refund(*gin.Context) {}
+
+func (*recordingBillingSettler) NeedsRefund() bool { return false }
+
+func (s *recordingBillingSettler) GetPreConsumedQuota() int {
+	return s.preConsumedQuota
+}
+
+func (s *recordingBillingSettler) Reserve(targetQuota int) error {
+	s.reserveTargets = append(s.reserveTargets, targetQuota)
+	if targetQuota > s.preConsumedQuota {
+		s.preConsumedQuota = targetQuota
+	}
+	return nil
+}
+
+func TestPrepareTieredBillingForSelectedGroupUpdatesReservation(t *testing.T) {
+	const expr = `tier("base", p)`
+	billing := &recordingBillingSettler{preConsumedQuota: 50_000}
+	relayInfo := &relaycommon.RelayInfo{
+		Billing:               billing,
+		FinalPreConsumedQuota: 50_000,
+		TieredBillingSnapshot: &billingexpr.BillingSnapshot{
+			BillingMode:               "tiered_expr",
+			ExprString:                expr,
+			ExprHash:                  billingexpr.ExprHashString(expr),
+			GroupRatio:                0.10,
+			EstimatedQuotaBeforeGroup: 500_000,
+			EstimatedQuotaAfterGroup:  50_000,
+			QuotaPerUnit:              testQuotaPerUnit,
+		},
+		PriceData: types.PriceData{
+			GroupRatioInfo: types.GroupRatioInfo{GroupRatio: 0.20},
+		},
+	}
+
+	require.Nil(t, PrepareTieredBillingForSelectedGroup(nil, relayInfo))
+	require.Equal(t, []int{100_000}, billing.reserveTargets)
+	assert.Equal(t, 100_000, billing.preConsumedQuota)
+	assert.Equal(t, 100_000, relayInfo.FinalPreConsumedQuota)
+	assert.Equal(t, 0.20, relayInfo.TieredBillingSnapshot.GroupRatio)
+	assert.Equal(t, 100_000, relayInfo.TieredBillingSnapshot.EstimatedQuotaAfterGroup)
+}
+
+func TestPrepareTieredBillingForSelectedGroupStartsBillingAfterFreeGroup(t *testing.T) {
+	truncate(t)
+	gin.SetMode(gin.TestMode)
+
+	const userID = 700
+	seedUser(t, userID, 500_000)
+
+	relayInfo := &relaycommon.RelayInfo{
+		UserId:          userID,
+		IsPlayground:    true,
+		ForcePreConsume: true,
+		OriginModelName: "gpt-test",
+		UserSetting: dto.UserSetting{
+			BillingPreference: "wallet_only",
+		},
+		TieredBillingSnapshot: &billingexpr.BillingSnapshot{
+			BillingMode:               "tiered_expr",
+			ExprString:                `tier("base", p)`,
+			ExprHash:                  billingexpr.ExprHashString(`tier("base", p)`),
+			GroupRatio:                0,
+			EstimatedQuotaBeforeGroup: 500_000,
+			QuotaPerUnit:              testQuotaPerUnit,
+		},
+		PriceData: types.PriceData{
+			GroupRatioInfo: types.GroupRatioInfo{GroupRatio: 0.20},
+		},
+	}
+	ctx, _ := gin.CreateTestContext(nil)
+
+	require.Nil(t, PrepareTieredBillingForSelectedGroup(ctx, relayInfo))
+	require.NotNil(t, relayInfo.Billing)
+	assert.Equal(t, 100_000, relayInfo.FinalPreConsumedQuota)
+	assert.Equal(t, 0.20, relayInfo.TieredBillingSnapshot.GroupRatio)
+	assert.Equal(t, 100_000, relayInfo.TieredBillingSnapshot.EstimatedQuotaAfterGroup)
+
+	userQuota, err := model.GetUserQuota(userID, false)
+	require.NoError(t, err)
+	assert.Equal(t, 400_000, userQuota)
+}
+
+func TestTryTieredSettleUsesFinalGroupAfterRetry(t *testing.T) {
+	const expr = `tier("base", p)`
+	tests := []struct {
+		name            string
+		finalGroupRatio float64
+		wantQuota       int
+	}{
+		{name: "more expensive final group", finalGroupRatio: 0.20, wantQuota: 100_000},
+		{name: "free final group", finalGroupRatio: 0, wantQuota: 0},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			relayInfo := &relaycommon.RelayInfo{
+				Billing:               &recordingBillingSettler{preConsumedQuota: 50_000},
+				FinalPreConsumedQuota: 50_000,
+				TieredBillingSnapshot: &billingexpr.BillingSnapshot{
+					BillingMode:               "tiered_expr",
+					ExprString:                expr,
+					ExprHash:                  billingexpr.ExprHashString(expr),
+					GroupRatio:                0.10,
+					EstimatedQuotaBeforeGroup: 500_000,
+					EstimatedQuotaAfterGroup:  50_000,
+					QuotaPerUnit:              testQuotaPerUnit,
+				},
+				PriceData: types.PriceData{
+					GroupRatioInfo: types.GroupRatioInfo{GroupRatio: tt.finalGroupRatio},
+				},
+			}
+
+			require.Nil(t, PrepareTieredBillingForSelectedGroup(nil, relayInfo))
+			ok, quota, result := TryTieredSettle(relayInfo, billingexpr.TokenParams{P: 1_000_000})
+
+			require.True(t, ok)
+			require.NotNil(t, result)
+			assert.Equal(t, tt.wantQuota, quota)
+			assert.Equal(t, tt.finalGroupRatio, relayInfo.TieredBillingSnapshot.GroupRatio)
+			assert.Equal(t, tt.wantQuota, relayInfo.TieredBillingSnapshot.EstimatedQuotaAfterGroup)
+		})
+	}
+}
+
 func TestTryTieredSettle_GroupRatioScaling(t *testing.T) {
 	info := makeRelayInfo(flatExpr, 1.5, 1000, 500)