fix(gemini): resolve customtools alias in mapping lookup

backend/internal/service/account.go

@@ -515,6 +515,45 @@ func ensureAntigravityDefaultPassthroughs(mapping map[string]string, models []st
 	}
 }
 
+func normalizeRequestedModelForLookup(platform, requestedModel string) string {
+	trimmed := strings.TrimSpace(requestedModel)
+	if trimmed == "" {
+		return ""
+	}
+	if platform != PlatformGemini && platform != PlatformAntigravity {
+		return trimmed
+	}
+	if trimmed == "gemini-3.1-pro-preview-customtools" {
+		return "gemini-3.1-pro-preview"
+	}
+	return trimmed
+}
+
+func mappingSupportsRequestedModel(mapping map[string]string, requestedModel string) bool {
+	if requestedModel == "" {
+		return false
+	}
+	if _, exists := mapping[requestedModel]; exists {
+		return true
+	}
+	for pattern := range mapping {
+		if matchWildcard(pattern, requestedModel) {
+			return true
+		}
+	}
+	return false
+}
+
+func resolveRequestedModelInMapping(mapping map[string]string, requestedModel string) (mappedModel string, matched bool) {
+	if requestedModel == "" {
+		return "", false
+	}
+	if mappedModel, exists := mapping[requestedModel]; exists {
+		return mappedModel, true
+	}
+	return matchWildcardMappingResult(mapping, requestedModel)
+}
+
 // IsModelSupported 检查模型是否在 model_mapping 中（支持通配符）
 // 如果未配置 mapping，返回 true（允许所有模型）
 func (a *Account) IsModelSupported(requestedModel string) bool {
@@ -522,17 +561,11 @@ func (a *Account) IsModelSupported(requestedModel string) bool {
 	if len(mapping) == 0 {
 		return true // 无映射 = 允许所有
 	}
-	// 精确匹配
-	if _, exists := mapping[requestedModel]; exists {
+	if mappingSupportsRequestedModel(mapping, requestedModel) {
 		return true
 	}
-	// 通配符匹配
-	for pattern := range mapping {
-		if matchWildcard(pattern, requestedModel) {
-			return true
-		}
-	}
-	return false
+	normalized := normalizeRequestedModelForLookup(a.Platform, requestedModel)
+	return normalized != requestedModel && mappingSupportsRequestedModel(mapping, normalized)
 }
 
 // GetMappedModel 获取映射后的模型名（支持通配符，最长优先匹配）
@@ -549,12 +582,16 @@ func (a *Account) ResolveMappedModel(requestedModel string) (mappedModel string,
 	if len(mapping) == 0 {
 		return requestedModel, false
 	}
-	// 精确匹配优先
-	if mappedModel, exists := mapping[requestedModel]; exists {
+	if mappedModel, matched := resolveRequestedModelInMapping(mapping, requestedModel); matched {
 		return mappedModel, true
 	}
-	// 通配符匹配（最长优先）
-	return matchWildcardMappingResult(mapping, requestedModel)
+	normalized := normalizeRequestedModelForLookup(a.Platform, requestedModel)
+	if normalized != requestedModel {
+		if mappedModel, matched := resolveRequestedModelInMapping(mapping, normalized); matched {
+			return mappedModel, true
+		}
+	}
+	return requestedModel, false
 }
 
 func (a *Account) GetBaseURL() string {

backend/internal/service/account_wildcard_test.go

@@ -133,6 +133,7 @@ func TestMatchWildcardMappingResult(t *testing.T) {
 func TestAccountIsModelSupported(t *testing.T) {
 	tests := []struct {
 		name           string
+		platform       string
 		credentials    map[string]any
 		requestedModel string
 		expected       bool
@@ -184,6 +185,17 @@ func TestAccountIsModelSupported(t *testing.T) {
 			requestedModel: "claude-opus-4-5-thinking",
 			expected:       true,
 		},
+		{
+			name:     "gemini customtools alias matches normalized mapping",
+			platform: PlatformGemini,
+			credentials: map[string]any{
+				"model_mapping": map[string]any{
+					"gemini-3.1-pro-preview": "gemini-3.1-pro-preview",
+				},
+			},
+			requestedModel: "gemini-3.1-pro-preview-customtools",
+			expected:       true,
+		},
 		{
 			name: "wildcard match not supported",
 			credentials: map[string]any{
@@ -199,6 +211,7 @@ func TestAccountIsModelSupported(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			account := &Account{
+				Platform:    tt.platform,
 				Credentials: tt.credentials,
 			}
 			result := account.IsModelSupported(tt.requestedModel)
@@ -212,6 +225,7 @@ func TestAccountIsModelSupported(t *testing.T) {
 func TestAccountGetMappedModel(t *testing.T) {
 	tests := []struct {
 		name           string
+		platform       string
 		credentials    map[string]any
 		requestedModel string
 		expected       string
@@ -223,6 +237,13 @@ func TestAccountGetMappedModel(t *testing.T) {
 			requestedModel: "claude-sonnet-4-5",
 			expected:       "claude-sonnet-4-5",
 		},
+		{
+			name:           "no mapping preserves gemini customtools model",
+			platform:       PlatformGemini,
+			credentials:    nil,
+			requestedModel: "gemini-3.1-pro-preview-customtools",
+			expected:       "gemini-3.1-pro-preview-customtools",
+		},
 
 		// 精确匹配
 		{
@@ -250,6 +271,29 @@ func TestAccountGetMappedModel(t *testing.T) {
 		},
 
 		// 无匹配返回原始模型
+		{
+			name:     "gemini customtools alias resolves through normalized mapping",
+			platform: PlatformGemini,
+			credentials: map[string]any{
+				"model_mapping": map[string]any{
+					"gemini-3.1-pro-preview": "gemini-3.1-pro-preview",
+				},
+			},
+			requestedModel: "gemini-3.1-pro-preview-customtools",
+			expected:       "gemini-3.1-pro-preview",
+		},
+		{
+			name:     "gemini customtools exact mapping wins over normalized fallback",
+			platform: PlatformGemini,
+			credentials: map[string]any{
+				"model_mapping": map[string]any{
+					"gemini-3.1-pro-preview":             "gemini-3.1-pro-preview",
+					"gemini-3.1-pro-preview-customtools": "gemini-3.1-pro-preview-customtools",
+				},
+			},
+			requestedModel: "gemini-3.1-pro-preview-customtools",
+			expected:       "gemini-3.1-pro-preview-customtools",
+		},
 		{
 			name: "no match returns original",
 			credentials: map[string]any{
@@ -265,6 +309,7 @@ func TestAccountGetMappedModel(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			account := &Account{
+				Platform:    tt.platform,
 				Credentials: tt.credentials,
 			}
 			result := account.GetMappedModel(tt.requestedModel)
@@ -278,6 +323,7 @@ func TestAccountGetMappedModel(t *testing.T) {
 func TestAccountResolveMappedModel(t *testing.T) {
 	tests := []struct {
 		name           string
+		platform       string
 		credentials    map[string]any
 		requestedModel string
 		expectedModel  string
@@ -312,6 +358,31 @@ func TestAccountResolveMappedModel(t *testing.T) {
 			expectedModel:  "gpt-5.4",
 			expectedMatch:  true,
 		},
+		{
+			name:     "gemini customtools alias reports normalized match",
+			platform: PlatformGemini,
+			credentials: map[string]any{
+				"model_mapping": map[string]any{
+					"gemini-3.1-pro-preview": "gemini-3.1-pro-preview",
+				},
+			},
+			requestedModel: "gemini-3.1-pro-preview-customtools",
+			expectedModel:  "gemini-3.1-pro-preview",
+			expectedMatch:  true,
+		},
+		{
+			name:     "gemini customtools exact mapping reports exact match",
+			platform: PlatformGemini,
+			credentials: map[string]any{
+				"model_mapping": map[string]any{
+					"gemini-3.1-pro-preview":             "gemini-3.1-pro-preview",
+					"gemini-3.1-pro-preview-customtools": "gemini-3.1-pro-preview-customtools",
+				},
+			},
+			requestedModel: "gemini-3.1-pro-preview-customtools",
+			expectedModel:  "gemini-3.1-pro-preview-customtools",
+			expectedMatch:  true,
+		},
 		{
 			name: "missing mapping reports unmatched",
 			credentials: map[string]any{
@@ -328,6 +399,7 @@ func TestAccountResolveMappedModel(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			account := &Account{
+				Platform:    tt.platform,
 				Credentials: tt.credentials,
 			}
 			mappedModel, matched := account.ResolveMappedModel(tt.requestedModel)

backend/internal/service/antigravity_model_mapping_test.go

@@ -268,6 +268,12 @@ func TestMapAntigravityModel_WildcardTargetEqualsRequest(t *testing.T) {
 			requestedModel: "gemini-2.5-flash",
 			expected:       "gemini-2.5-flash",
 		},
+		{
+			name:           "customtools alias falls back to normalized preview mapping",
+			modelMapping:   map[string]any{"gemini-3.1-pro-preview": "gemini-3.1-pro-high"},
+			requestedModel: "gemini-3.1-pro-preview-customtools",
+			expected:       "gemini-3.1-pro-high",
+		},
 	}
 
 	for _, tt := range tests {