fix(antigravity): keep legacy default passthroughs and bill Claude 5.5 tier IDs at base rates

- Restore runtime default passthroughs and Gemini 3.1 Pro aliases for
  explicit Antigravity model_mapping. Mappings saved before the Gemini
  3.x Flash / 3.1 Pro releases still depend on them; dropping them would
  silently remove those models from existing accounts on upgrade.
- Capability sync now skips injected-only passthrough targets, so models
  the upstream catalog omits no longer mark the sync as partial.
- Price Antigravity claude-{opus,sonnet}-5-5-{high,medium,low} at the base
  Opus/Sonnet 5.5 card instead of substring-matching claude-opus-5 /
  claude-sonnet-4-5 (1.25x-3x overbilling).

backend/internal/handler/gateway_models_test.go

@@ -1408,14 +1408,14 @@ func modelIDsForTest(models []gatewayModelItemForTest) []string {
 	return ids
 }
 
-func TestGatewayModels_AntigravityExplicitMappingDefinesBothCatalogs(t *testing.T) {
+func TestGatewayModels_AntigravityExplicitMappingAppearsInBothCatalogs(t *testing.T) {
 	gin.SetMode(gin.TestMode)
 	const groupID int64 = 93
 	mapping := map[string]any{
-		"gemini-3.8-flash":      "gemini-3.8-flash-high",
-		"gemini-3.8-flash-high": "gemini-3.8-flash-high",
-		"claude-opus-5-5-high":  "claude-opus-5-5-high",
-		"gemini-pro-agent":      "gemini-pro-agent",
+		"gemini-3.8-flash":         "gemini-3.8-flash-high",
+		"gemini-3.8-flash-high":    "gemini-3.8-flash-high",
+		"claude-opus-4-6-thinking": "claude-opus-4-6-thinking",
+		"gemini-pro-agent":         "gemini-pro-agent",
 	}
 	for _, platform := range []string{service.PlatformAntigravity, service.PlatformComposite, service.PlatformGemini} {
 		t.Run(platform, func(t *testing.T) {
@@ -1426,7 +1426,7 @@ func TestGatewayModels_AntigravityExplicitMappingDefinesBothCatalogs(t *testing.
 					Credentials: map[string]any{"model_mapping": mapping},
 				}}},
 			})
-			want := []string{"gemini-3.8-flash", "gemini-3.8-flash-high", "gemini-pro-agent", "claude-opus-5-5-high"}
+			want := []string{"gemini-3.8-flash", "gemini-3.8-flash-high", "gemini-pro-agent", "claude-opus-4-6-thinking"}
 			if platform == service.PlatformGemini {
 				want = want[:3]
 			}
@@ -1452,7 +1452,11 @@ func TestGatewayModels_AntigravityExplicitMappingDefinesBothCatalogs(t *testing.
 					ids = modelIDsForTest(got.Data)
 				}
 				require.Equal(t, http.StatusOK, rec.Code)
-				require.ElementsMatch(t, want, ids, "codex=%t", codex)
+				// 显式条目必须同时出现在两种目录；默认透传补齐的条目不锁定。
+				require.Subset(t, ids, want, "codex=%t", codex)
+				if platform == service.PlatformGemini {
+					require.NotContains(t, ids, "claude-opus-4-6-thinking", "codex=%t", codex)
+				}
 			}
 		})
 	}
@@ -1517,7 +1521,12 @@ func TestGatewayModels_GeminiGroupIncludesAntigravityGeminiMappings(t *testing.T
 	var got gatewayModelsResponseForTest
 	require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &got))
 	ids := modelIDsForTest(got.Data)
-	require.ElementsMatch(t, []string{"gemini-3.8-flash-high", "gemini-synced-custom", "gemini-3.8-flash-low", "gemini-native-only"}, ids)
+	// 账号显式配置的 gemini-* 映射必须出现（resolveModelMapping 还会补一组 antigravity
+	// 默认透传别名，这里只断言显式条目与排除项，不锁定补齐后的完整集合）。
+	require.Contains(t, ids, "gemini-3.8-flash-high")
+	require.Contains(t, ids, "gemini-synced-custom")
+	require.Contains(t, ids, "gemini-3.8-flash-low")
+	require.Contains(t, ids, "gemini-native-only")
 	require.NotContains(t, ids, "gemini-disabled-only")
 	require.NotContains(t, ids, "gemini-unset-only")
 	// antigravity 账号的 claude-* 映射与 anthropic 账号的映射都不应出现在 gemini 分组。

backend/internal/service/account.go

@@ -8,6 +8,7 @@ import (
 	"log/slog"
 	"net/url"
 	"reflect"
+	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -690,8 +691,7 @@ func (a *Account) resolveModelMapping(rawMapping map[string]any) map[string]stri
 	}
 	if len(result) > 0 {
 		if a.Platform == domain.PlatformAntigravity {
-			// Explicit mappings define this account's whitelist. Injecting static
-			// defaults re-enables retired models after an upstream model sync.
+			ensureAntigravityDefaultPassthroughs(result, antigravityDefaultPassthroughModels)
 			applyAntigravityGemini31ProAliases(result)
 		}
 		return result
@@ -741,6 +741,72 @@ func modelMappingSignature(rawMapping map[string]any) uint64 {
 	return h.Sum64()
 }
 
+// antigravityDefaultPassthroughModels 是 Antigravity 显式 model_mapping 运行时补齐的默认透传条目：
+// 让新模型发布前保存的映射也能调用这些模型。
+var antigravityDefaultPassthroughModels = []string{
+	"gemini-3-flash",
+	"gemini-3.1-pro-high",
+	"gemini-3.1-pro-low",
+	"gemini-3.6-flash",
+	"gemini-3.6-flash-high",
+	"gemini-3.6-flash-low",
+	"gemini-3.6-flash-medium",
+	"gemini-3.6-flash-tiered",
+	"gemini-3.7-flash",
+	"gemini-3.7-flash-high",
+	"gemini-3.7-flash-low",
+	"gemini-3.7-flash-medium",
+	"gemini-3.7-flash-tiered",
+	"gemini-3.8-flash",
+	"gemini-3.8-flash-high",
+	"gemini-3.8-flash-low",
+	"gemini-3.8-flash-medium",
+	"gemini-3.8-flash-tiered",
+}
+
+// isAntigravityInjectedDefaultPassthrough 判断 GetModelMapping 中的 key→target 是否仅由
+// resolveModelMapping 运行时补齐（管理员未写入 credentials.model_mapping）。
+func (a *Account) isAntigravityInjectedDefaultPassthrough(key, target string) bool {
+	if a == nil || a.Platform != domain.PlatformAntigravity || key != target || !slices.Contains(antigravityDefaultPassthroughModels, key) {
+		return false
+	}
+	rawMapping, _ := a.Credentials["model_mapping"].(map[string]any)
+	hasExplicitEntry := false
+	for _, v := range rawMapping {
+		if _, ok := v.(string); ok {
+			hasExplicitEntry = true
+			break
+		}
+	}
+	if !hasExplicitEntry {
+		// 空映射走默认目录，不做运行时补齐。
+		return false
+	}
+	_, configured := rawMapping[key].(string)
+	return !configured
+}
+
+func ensureAntigravityDefaultPassthrough(mapping map[string]string, model string) {
+	if mapping == nil || model == "" {
+		return
+	}
+	if _, exists := mapping[model]; exists {
+		return
+	}
+	for pattern := range mapping {
+		if matchWildcard(pattern, model) {
+			return
+		}
+	}
+	mapping[model] = model
+}
+
+func ensureAntigravityDefaultPassthroughs(mapping map[string]string, models []string) {
+	for _, model := range models {
+		ensureAntigravityDefaultPassthrough(mapping, model)
+	}
+}
+
 func applyAntigravityGemini31ProAliases(mapping map[string]string) {
 	target := strings.TrimSpace(mapping[domain.AntigravityGemini31ProAgentModel])
 	if target == "" {
@@ -774,13 +840,26 @@ func applyAntigravityGemini31ProAliases(mapping map[string]string) {
 
 	for _, alias := range aliases {
 		current, exists := mapping[alias.model]
-		if !exists {
+		if exists {
+			if _, legacy := alias.legacyTargets[current]; legacy {
+				mapping[alias.model] = target
+			}
 			continue
 		}
-		if _, legacy := alias.legacyTargets[current]; legacy {
-			mapping[alias.model] = target
+		if mappingHasWildcardForModel(mapping, alias.model) {
+			continue
+		}
+		mapping[alias.model] = target
+	}
+}
+
+func mappingHasWildcardForModel(mapping map[string]string, model string) bool {
+	for pattern := range mapping {
+		if matchWildcard(pattern, model) {
+			return true
 		}
 	}
+	return false
 }
 
 func normalizeRequestedModelForLookup(platform, requestedModel string) string {

backend/internal/service/account_wildcard_test.go

@@ -437,8 +437,8 @@ func TestAccountGetModelMapping_AntigravityNormalizesGemini31ProAliases(t *testi
 
 	mapping := account.GetModelMapping()
 
-	if account.IsModelSupported("gemini-3.1-pro") {
-		t.Fatal("legacy target normalization must not add an unconfigured alias")
+	if got := mapping["gemini-3.1-pro"]; got != domain.AntigravityGemini31ProAgentModel {
+		t.Fatalf("expected gemini-3.1-pro to map to %q, got %q", domain.AntigravityGemini31ProAgentModel, got)
 	}
 	if got := mapping["gemini-3.1-pro-high"]; got != domain.AntigravityGemini31ProAgentModel {
 		t.Fatalf("expected gemini-3.1-pro-high to map to %q, got %q", domain.AntigravityGemini31ProAgentModel, got)
@@ -470,8 +470,8 @@ func TestAccountGetModelMapping_AntigravityPreservesGemini31ProOverrides(t *test
 	if got := mapping["gemini-3.1-pro-preview"]; got != "custom-preview" {
 		t.Fatalf("expected gemini-3.1-pro-preview override to be preserved, got %q", got)
 	}
-	if account.IsModelSupported("gemini-3.1-pro") {
-		t.Fatal("explicit overrides must not add an unconfigured alias")
+	if got := mapping["gemini-3.1-pro"]; got != domain.AntigravityGemini31ProAgentModel {
+		t.Fatalf("expected gemini-3.1-pro alias to default to %q, got %q", domain.AntigravityGemini31ProAgentModel, got)
 	}
 }
 
@@ -591,7 +591,7 @@ func TestAccountResolveMappedModel(t *testing.T) {
 	}
 }
 
-func TestAccountGetModelMapping_AntigravityExplicitWhitelistDoesNotReenableDefaults(t *testing.T) {
+func TestAccountGetModelMapping_AntigravityEnsuresGeminiDefaultPassthroughs(t *testing.T) {
 	account := &Account{
 		Platform: PlatformAntigravity,
 		Credentials: map[string]any{
@@ -602,13 +602,14 @@ func TestAccountGetModelMapping_AntigravityExplicitWhitelistDoesNotReenableDefau
 	}
 
 	mapping := account.GetModelMapping()
-	if len(mapping) != 1 || account.GetMappedModel("gemini-3-pro-high") != "gemini-3.1-pro-high" {
-		t.Fatalf("expected the explicit alias to be retained, got %v", mapping)
+	if mapping["gemini-3-flash"] != "gemini-3-flash" {
+		t.Fatalf("expected gemini-3-flash passthrough to be auto-filled, got: %q", mapping["gemini-3-flash"])
 	}
-	for _, model := range []string{"gemini-3-flash", "gemini-3.1-pro-high", "gemini-3.1-pro-low", "gemini-3.7-flash-high", "claude-opus-5-5-high"} {
-		if account.IsModelSupported(model) {
-			t.Fatalf("explicit whitelist must not re-enable %q", model)
-		}
+	if mapping["gemini-3.1-pro-high"] != "gemini-3.1-pro-high" {
+		t.Fatalf("expected gemini-3.1-pro-high passthrough to be auto-filled, got: %q", mapping["gemini-3.1-pro-high"])
+	}
+	if mapping["gemini-3.1-pro-low"] != "gemini-3.1-pro-low" {
+		t.Fatalf("expected gemini-3.1-pro-low passthrough to be auto-filled, got: %q", mapping["gemini-3.1-pro-low"])
 	}
 }
 

backend/internal/service/antigravity_gemini_thinking_variant_test.go

@@ -77,7 +77,8 @@ func TestResolveGeminiThinkingVariant(t *testing.T) {
 		{"only -high exists: low request degrades to high", map[string]string{
 			"gemini-3.5-flash-high": "gemini-3.5-flash-high",
 		}, "gemini-3.5-flash", budget("1000"), "gemini-3.5-flash-high", true},
-		{"unconfigured default variants stay unavailable", catalog, "gemini-3.6-flash", budget("1000"), "gemini-3.6-flash-high", true},
+		// gemini-3.6/3.7/3.8-flash 的四个变体会被 resolveModelMapping 自动补齐（存量显式映射账号的兼容透传）。
+		{"injected default variants are usable", catalog, "gemini-3.6-flash", budget("1000"), "gemini-3.6-flash-low", true},
 		{"already suffixed: untouched", catalog, "gemini-3.8-flash-low", budget("-1"), "", false},
 		{"bare name explicitly mapped: untouched", catalog, "gemini-2.5-flash", budget("-1"), "", false},
 		{"no variants in mapping: untouched", catalog, "gemini-9.9-flash", budget("-1"), "", false},
@@ -89,10 +90,15 @@ func TestResolveGeminiThinkingVariant(t *testing.T) {
 		{"variant value is itself a mapping target", map[string]string{
 			"gemini-3.8-flash-high": "gemini-3.8-flash-tiered",
 		}, "gemini-3.8-flash", budget("-1"), "gemini-3.8-flash-tiered", true},
+		// 前端持久化的默认目录含裸名自映射；-low 由默认透传补齐，按预算命中。
 		{"persisted default bare identity passthrough still resolves when variants exist", map[string]string{
 			"gemini-3.8-flash":      "gemini-3.8-flash",
 			"gemini-3.8-flash-high": "gemini-3.8-flash-high",
-		}, "gemini-3.8-flash", budget("1000"), "gemini-3.8-flash-high", true},
+		}, "gemini-3.8-flash", budget("1000"), "gemini-3.8-flash-low", true},
+		{"bare identity passthrough resolves a configured variant outside the default passthroughs", map[string]string{
+			"gemini-3.5-flash":      "gemini-3.5-flash",
+			"gemini-3.5-flash-high": "gemini-3.5-flash-high",
+		}, "gemini-3.5-flash", budget("1000"), "gemini-3.5-flash-high", true},
 		{"wildcard mapping does not fabricate variants for non-tiered bare model", map[string]string{
 			"gemini-2.5*": "gemini-2.5-flash",
 		}, "gemini-2.5-flash", budget("-1"), "", false},

backend/internal/service/billing_service.go

@@ -1035,7 +1035,7 @@ func (s *BillingService) initFallbackPricing() {
 
 // getFallbackPricing 根据模型系列获取回退价格
 func (s *BillingService) getFallbackPricing(model string) *ModelPricing {
-	modelLower := strings.ToLower(model)
+	modelLower := normalizeAntigravityClaudeTierAlias(strings.ToLower(model))
 	if modelLower == "jev-latest" {
 		return s.fallbackPrices["jev-latest"]
 	}

backend/internal/service/pricing_service.go

@@ -1309,7 +1309,7 @@ func (s *PricingService) buildModelLookupCandidates(modelLower string) []string
 	// one later. Antigravity's Gemini thinking tiers share the base rate,
 	// so the normalized base remains the fallback after the exact aliases.
 	candidates := rawCandidates
-	if normalizeGeminiThinkingTierAlias(lastSegment(modelLower)) != lastSegment(modelLower) {
+	if isAntigravityThinkingTierAlias(lastSegment(modelLower)) {
 		candidates = append(candidates, normalized)
 	} else {
 		// Prefer canonical model names for all other aliases (including models/xxx).
@@ -1365,7 +1365,29 @@ func normalizeModelNameForPricing(model string) string {
 		}
 		return canonical
 	}
-	return normalizeGeminiThinkingTierAlias(model)
+	return normalizeAntigravityClaudeTierAlias(normalizeGeminiThinkingTierAlias(model))
+}
+
+// normalizeAntigravityClaudeTierAlias maps Antigravity's Claude 5.5 thinking-tier
+// model IDs (claude-opus-5-5-high, claude-sonnet-5-5-low, ...) to the public base
+// model. Like the Gemini tiers, the suffix selects reasoning depth rather than a
+// separate token rate; without this the IDs fall into substring family matching
+// and are billed as claude-opus-5 / claude-sonnet-4-5.
+func normalizeAntigravityClaudeTierAlias(model string) string {
+	for _, baseModel := range []string{"claude-opus-5-5", "claude-sonnet-5-5"} {
+		for _, tier := range []string{"-high", "-low", "-medium"} {
+			if model == baseModel+tier {
+				return baseModel
+			}
+		}
+	}
+	return model
+}
+
+// isAntigravityThinkingTierAlias reports whether model is an Antigravity
+// Gemini or Claude thinking-tier alias of a priced base model.
+func isAntigravityThinkingTierAlias(model string) bool {
+	return normalizeGeminiThinkingTierAlias(model) != model || normalizeAntigravityClaudeTierAlias(model) != model
 }
 
 // normalizeGeminiThinkingTierAlias maps Antigravity's Gemini thinking-tier
@@ -1411,6 +1433,7 @@ func (s *PricingService) extractBaseName(model string) string {
 
 // matchByModelFamily 基于模型系列匹配
 func (s *PricingService) matchByModelFamily(model string) *LiteLLMModelPricing {
+	model = normalizeAntigravityClaudeTierAlias(model)
 	if claude.IsOpus55(model) {
 		if pricing, ok := s.pricingData["claude-opus-5-5"]; ok {
 			return pricing

backend/internal/service/pricing_service_test.go

@@ -1278,3 +1278,42 @@ func TestCalculateCost_ClaudeSonnetCatalogLadderIsDataDriven(t *testing.T) {
 	require.NoError(t, err)
 	require.False(t, cost.LongContextBillingApplied, "恰好 200000 不进高档（严格大于）")
 }
+
+// Antigravity 的 Claude 5.5 思考档位 ID 只决定推理深度，必须按基础型号计价，
+// 不能落入子串家族匹配（opus-5-5-high → claude-opus-5、sonnet-5-5-high → sonnet-4-5）。
+func TestPricingService_AntigravityClaude55TiersUseBaseModelPricing(t *testing.T) {
+	opus := &LiteLLMModelPricing{InputCostPerToken: 4e-6, OutputCostPerToken: 20e-6}
+	sonnet := &LiteLLMModelPricing{InputCostPerToken: 2e-6, OutputCostPerToken: 10e-6}
+	svc := &PricingService{pricingData: map[string]*LiteLLMModelPricing{
+		"claude-opus-5-5":   opus,
+		"claude-sonnet-5-5": sonnet,
+		"claude-opus-5":     {InputCostPerToken: 5e-6, OutputCostPerToken: 25e-6},
+		"claude-sonnet-4-5": {InputCostPerToken: 3e-6, OutputCostPerToken: 15e-6},
+	}}
+	for _, tier := range []string{"high", "medium", "low"} {
+		require.Same(t, opus, svc.GetModelPricing("claude-opus-5-5-"+tier))
+		require.Same(t, sonnet, svc.GetModelPricing("claude-sonnet-5-5-"+tier))
+	}
+
+	// 价格目录缺基础型号时走家族兜底，同样不能落到 claude-opus-5 / sonnet-4-5。
+	sparse := &PricingService{pricingData: map[string]*LiteLLMModelPricing{
+		"claude-opus-5":     {InputCostPerToken: 5e-6, OutputCostPerToken: 25e-6},
+		"claude-sonnet-4-5": {InputCostPerToken: 3e-6, OutputCostPerToken: 15e-6},
+	}}
+	require.Same(t, claudeOpus55FallbackPricing, sparse.GetModelPricing("claude-opus-5-5-high"))
+	require.Same(t, claudeSonnet55FallbackPricing, sparse.GetModelPricing("claude-sonnet-5-5-low"))
+}
+
+func TestBillingService_AntigravityClaude55TierFallbacksUseBaseRates(t *testing.T) {
+	svc := NewBillingService(&config.Config{}, nil)
+	tokens := UsageTokens{InputTokens: 1_000_000, OutputTokens: 1_000_000}
+	for _, tier := range []string{"high", "medium", "low"} {
+		for base, want := range map[string]string{"claude-opus-5-5": "claude-opus-5-5", "claude-sonnet-5-5": "claude-sonnet-5-5"} {
+			got, err := svc.CalculateCost(base+"-"+tier, tokens, 1)
+			require.NoError(t, err)
+			ref, err := svc.CalculateCost(want, tokens, 1)
+			require.NoError(t, err)
+			require.InDelta(t, ref.TotalCost, got.TotalCost, 1e-12, base+"-"+tier)
+		}
+	}
+}

backend/internal/service/upstream_models.go

@@ -340,7 +340,11 @@ func configuredUpstreamModelsForCapabilitySync(account *Account) []string {
 		return nil
 	}
 	models := make([]string, 0)
-	for _, mappedModel := range account.GetModelMapping() {
+	for requestedModel, mappedModel := range account.GetModelMapping() {
+		// Antigravity 运行时补齐的默认透传不是管理员配置的目标，上游目录未列出时不应拉低能力同步完整度。
+		if account.isAntigravityInjectedDefaultPassthrough(requestedModel, mappedModel) {
+			continue
+		}
 		mappedModel = strings.TrimSpace(mappedModel)
 		if mappedModel == "" || strings.Contains(mappedModel, "*") {
 			continue

backend/internal/service/upstream_models_antigravity_test.go

@@ -223,3 +223,23 @@ func TestSyncUpstreamModelCatalogAntigravityBudgetReasoningLevels(t *testing.T)
 		})
 	}
 }
+
+func TestConfiguredUpstreamModelsForCapabilitySyncSkipsInjectedAntigravityPassthroughs(t *testing.T) {
+	account := &Account{
+		Platform: PlatformAntigravity,
+		Credentials: map[string]any{"model_mapping": map[string]any{
+			"gemini-3.8-flash-high": "gemini-3.8-flash-high",
+			"gemini-3.8-flash":      "gemini-3.8-flash-tiered",
+			"custom-alias":          "gemini-3.6-flash-low",
+		}},
+	}
+	// 运行时补齐的默认透传仍可调用（存量账号兼容）。
+	require.True(t, account.IsModelSupported("gemini-3.7-flash-medium"))
+
+	got := configuredUpstreamModelsForCapabilitySync(account)
+	require.ElementsMatch(t, []string{"gemini-3.8-flash-high", "gemini-3.8-flash-tiered", "gemini-3.6-flash-low"}, got)
+
+	// 空映射走默认目录，其中的同名条目不是运行时补齐。
+	empty := &Account{Platform: PlatformAntigravity, Credentials: map[string]any{}}
+	require.Contains(t, configuredUpstreamModelsForCapabilitySync(empty), "gemini-3.8-flash-low")
+}