fix(openai): respect GPT-5.5 retirement on ChatGPT upstreams

backend/internal/handler/gateway_handler.go

@@ -1193,7 +1193,7 @@ func (h *GatewayHandler) Models(c *gin.Context) {
 		return
 	}
 
-	if len(availableModels) > 0 {
+	if len(availableModels) > 0 || (platform == service.PlatformOpenAI && availableModels != nil) {
 		writeModelsList(c, platform, availableModels)
 		return
 	}
@@ -1308,7 +1308,7 @@ func (h *GatewayHandler) compositeAvailableModels(ctx context.Context, groupID *
 			continue
 		}
 		platformModels := h.gatewayService.GetAvailableModels(ctx, groupID, platform)
-		if len(platformModels) == 0 {
+		if len(platformModels) == 0 && (platform != service.PlatformOpenAI || platformModels == nil) {
 			// CN 供应商没有静态默认模型列表（defaultModelIDsForPlatform 的
 			// default 分支是 Claude 列表），composite 下只暴露账号映射键。
 			if _, ok := schedulablePlatforms[platform]; ok && !service.IsMultiProtocolAPIKeyProvider(platform) {
@@ -1457,6 +1457,9 @@ func writeOpenAIModelsList(c *gin.Context, modelIDs []string) {
 // 与平台默认列表（fallbackModels）。账号映射为空时回落默认列表；Anthropic
 // 平台两者取并集，其余平台以账号映射键为准。
 func modelListingSource(platform string, availableModels, fallbackModels []string) []string {
+	if platform == service.PlatformOpenAI && availableModels != nil {
+		return availableModels
+	}
 	if len(availableModels) == 0 {
 		return fallbackModels
 	}

backend/internal/handler/gateway_models_test.go

@@ -324,6 +324,12 @@ func TestGatewayModels_UnmappedOpenAIAccountsSupplementMappedModels(t *testing.T
 			Credentials: map[string]any{"model_mapping": map[string]any{alias: "gpt-5.6-sol"}},
 		},
 	}
+	subscriptionDefaults := make([]string, 0)
+	for _, model := range openai.DefaultModelIDs() {
+		if model != "gpt-5.5" {
+			subscriptionDefaults = append(subscriptionDefaults, model)
+		}
+	}
 	tests := []struct {
 		name     string
 		accounts []service.Account
@@ -333,7 +339,7 @@ func TestGatewayModels_UnmappedOpenAIAccountsSupplementMappedModels(t *testing.T
 		{
 			name:     "unmapped parent and Spark shadow retain defaults and aliases",
 			accounts: accounts,
-			want:     append(openai.DefaultModelIDs(), alias),
+			want:     append(append([]string{}, subscriptionDefaults...), alias),
 		},
 		{
 			name:     "unmapped API key account also contributes defaults",
@@ -343,7 +349,7 @@ func TestGatewayModels_UnmappedOpenAIAccountsSupplementMappedModels(t *testing.T
 		{
 			name:     "unmapped accounts alone retain default response shape",
 			accounts: accounts[:1],
-			want:     openai.DefaultModelIDs(),
+			want:     subscriptionDefaults,
 		},
 		{
 			name:     "custom list can select defaults and aliases",
@@ -372,7 +378,7 @@ func TestGatewayModels_UnmappedOpenAIAccountsSupplementMappedModels(t *testing.T
 				Credentials: map[string]any{"model_mapping": map[string]any{"stale-model": "stale-model"}},
 				Extra:       map[string]any{"openai_passthrough": true},
 			}}, accounts[1:]...),
-			want: append(openai.DefaultModelIDs(), alias),
+			want: append(append([]string{}, subscriptionDefaults...), alias),
 		},
 		{
 			name:     "unmapped accounts from another platform do not add defaults",

backend/internal/handler/no_account_error.go

@@ -123,10 +123,14 @@ func classifyNoAccountError(
 
 	result := diag.DiagnoseModelAvailabilityForPlatform(ctx, apiKey.GroupID, routingModel, platform)
 	if result.HasAccountsInPool && !result.HasModelSupport {
+		message := fmt.Sprintf("Model %q is not supported by any configured account in this group", displayModel)
+		if result.HasRetiredSubscriptionModel {
+			message = fmt.Sprintf("Model %q targets GPT-5.5, which retired from Codex with ChatGPT sign-in on October 14, 2026. Select an available replacement such as GPT-6.1 Sol or GPT-6 Luna, or configure an API-key upstream that supports GPT-5.5.", displayModel)
+		}
 		return noAccountErrorClassification{
 			Status:        http.StatusNotFound,
 			ErrType:       "model_not_found",
-			Message:       fmt.Sprintf("Model %q is not supported by any configured account in this group", displayModel),
+			Message:       message,
 			ModelNotFound: true,
 		}
 	}

backend/internal/handler/no_account_error_test.go

@@ -303,3 +303,22 @@ func TestClassifySelectionFailureError_StillUpgradesNonModelNotFoundFallback(t *
 	require.Equal(t, "rate_limit_error", got.ErrType)
 	require.False(t, got.ModelNotFound)
 }
+
+func TestClassifyNoAccountError_GPT55Retirement(t *testing.T) {
+	groupID := int64(1)
+	apiKey := &service.APIKey{GroupID: &groupID}
+	fd := &fakeDiagnoser{resp: service.ModelAvailabilityDiagnosis{HasAccountsInPool: true, HasRetiredSubscriptionModel: true}}
+	cls := classifyNoAccountError(context.Background(), fd, apiKey, "gpt-5.5", "legacy", service.PlatformOpenAI)
+	require.Equal(t, http.StatusNotFound, cls.Status)
+	require.Equal(t, "model_not_found", cls.ErrType)
+	require.Contains(t, cls.Message, "retired")
+	require.Contains(t, cls.Message, "API-key")
+	fd.resp.HasModelSupport = true
+	cls = classifyNoAccountError(context.Background(), fd, apiKey, "gpt-5.5", "legacy", service.PlatformOpenAI)
+	require.Equal(t, http.StatusServiceUnavailable, cls.Status, "a temporarily unavailable API pool is not a retirement error")
+}
+
+func TestGPT55RetirementEmptyListingDoesNotUseDefaults(t *testing.T) {
+	require.Empty(t, modelListingSource(service.PlatformOpenAI, []string{}, []string{"gpt-5.5"}))
+	require.Equal(t, []string{"gpt-5.5"}, modelListingSource(service.PlatformOpenAI, nil, []string{"gpt-5.5"}))
+}

backend/internal/server/routes/gateway_models_pinned_test.go

@@ -27,6 +27,14 @@ func (r *pinnedModelsRoutesRepository) ListByGroup(context.Context, int64) ([]se
 	return []service.Account{r.account}, nil
 }
 
+func (r *pinnedModelsRoutesRepository) ListSchedulableByGroupID(context.Context, int64) ([]service.Account, error) {
+	return []service.Account{r.account}, nil
+}
+
+func (r *pinnedModelsRoutesRepository) ListModelAvailabilityCandidates(context.Context, *int64, []string, bool) ([]service.Account, error) {
+	return []service.Account{r.account}, nil
+}
+
 type pinnedModelsRoutesUpstream struct {
 	service.HTTPUpstream
 	ordinaryCalls atomic.Int32

backend/internal/service/account.go

@@ -914,6 +914,10 @@ func resolveRequestedModelInMapping(mapping map[string]string, requestedModel st
 // （isDeepseekServableModel）——未知模型名透传上游只会得到 404/400，并误触发
 // per-(账号,模型) 30 分钟冷却；带 [1m] 上下文后缀的写法先归一化再比对。
 func (a *Account) IsModelSupported(requestedModel string) bool {
+	return supportsOpenAIRequestModel(a, requestedModel, false)
+}
+
+func (a *Account) isModelMappingSupported(requestedModel string) bool {
 	// 透传模式仅替换认证、模型语义完全交由上游决定，因此放行所有模型。
 	// 该短路必须在 model_mapping 判定之前：账号从"白名单模式"切换到透传后，
 	// credentials 里常残留旧的非空 model_mapping，若不在此放行，透传账号会被

backend/internal/service/gateway_model_availability.go

@@ -21,6 +21,9 @@ type ModelAvailabilityDiagnosis struct {
 	// HasModelSupport is true if at least one account's model mapping admits
 	// the requested model.
 	HasModelSupport bool
+	// HasRetiredSubscriptionModel records a ChatGPT upstream blocked by model
+	// retirement, so an unsupported request can include migration guidance.
+	HasRetiredSubscriptionModel bool
 }
 
 // ModelAvailabilityDiagnoser is implemented by gateway services that can

backend/internal/service/gateway_service.go

@@ -22,6 +22,7 @@ import (
 	"github.com/Wei-Shaw/sub2api/internal/config"
 	"github.com/Wei-Shaw/sub2api/internal/domain"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/logger"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/openai"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/xai"
 	"github.com/Wei-Shaw/sub2api/internal/util/responseheaders"
 	"github.com/cespare/xxhash/v2"
@@ -1461,6 +1462,12 @@ func (s *GatewayService) GetAvailableModels(ctx context.Context, groupID *int64,
 	}
 
 	// If no account has model_mapping, return nil (use default)
+	if !hasAnyMapping && platform == PlatformOpenAI {
+		models := filterRetiredOpenAIModelIDs(accounts, openai.DefaultModelIDs())
+		if len(models) != len(openai.DefaultModels) {
+			return models
+		}
+	}
 	if !hasAnyMapping {
 		if s.modelsListCache != nil {
 			s.modelsListCache.Set(cacheKey, []string(nil), s.modelsListCacheTTL)
@@ -1478,6 +1485,12 @@ func (s *GatewayService) GetAvailableModels(ctx context.Context, groupID *int64,
 
 	if platform == PlatformOpenAI {
 		models = supplementUnmappedOpenAIModels(accounts, models)
+		models = filterRetiredOpenAIModelIDs(accounts, models)
+		// nil means "use defaults" to listing callers; an empty filtered catalog
+		// must remain authoritative instead of resurrecting retired defaults.
+		if len(models) == 0 {
+			return models
+		}
 	}
 
 	if s.modelsListCache != nil {

backend/internal/service/openai_account_scheduler.go

@@ -1812,7 +1812,7 @@ func (s *defaultOpenAIAccountScheduler) isAccountRequestCompatibleReason(ctx con
 	}) {
 		return false, "shadow_parent_unhealthy"
 	}
-	if req.RequestedModel != "" && !account.IsModelSupported(req.RequestedModel) {
+	if req.RequestedModel != "" && !supportsOpenAIRequestModel(account, req.RequestedModel, req.RequireCompact) {
 		return false, "model_not_supported"
 	}
 	if req.GroupID != nil && s != nil && s.service != nil &&

backend/internal/service/openai_codex_models_service.go

@@ -187,13 +187,13 @@ func (s *OpenAIGatewayService) MergeGroupConfiguredCodexModels(
 		return nil
 	}
 
+	visible, accounts, err := loadCodexGroupCatalogAccounts(ctx, s.accountRepo, group.ID)
+	if err != nil {
+		return fmt.Errorf("load group configured Codex models: %w", err)
+	}
 	var configuredModels []string
 	if !group.CodexModelsManifestConfig.Enabled {
-		var err error
-		configuredModels, err = s.groupConfiguredCodexModelIDs(ctx, group)
-		if err != nil {
-			return fmt.Errorf("load group configured Codex models: %w", err)
-		}
+		configuredModels = openAIConfiguredCodexModelIDsForGroup(visible, group)
 	}
 	body, changed, err := mergeConfiguredCodexModelsManifest(
 		manifest.Body,
@@ -211,7 +211,12 @@ func (s *OpenAIGatewayService) MergeGroupConfiguredCodexModels(
 		}
 		changed = true
 	}
-	if changed {
+	filtered, retired, err := filterRetiredOpenAIModelsBody(body, accounts, true)
+	if err != nil {
+		return fmt.Errorf("filter retired Codex models: %w", err)
+	}
+	body = filtered
+	if changed || retired {
 		manifest.Body = body
 		manifest.ETag = codexModelsManifestBodyETag(body)
 	}
@@ -222,17 +227,6 @@ func (s *OpenAIGatewayService) MergeGroupConfiguredCodexModels(
 	return nil
 }
 
-func (s *OpenAIGatewayService) groupConfiguredCodexModelIDs(ctx context.Context, group *Group) ([]string, error) {
-	if group == nil {
-		return nil, nil
-	}
-	accounts, err := s.accountRepo.ListSchedulableByGroupID(ctx, group.ID)
-	if err != nil {
-		return nil, err
-	}
-	return openAIConfiguredCodexModelIDsForGroup(accounts, group), nil
-}
-
 // loadCodexGroupCatalogAccounts separates picker membership from capability
 // intersection. visible accounts are currently schedulable and decide which
 // public aliases appear. catalog accounts are persistently enabled group
@@ -300,7 +294,7 @@ func openAIConfiguredCodexModelIDs(accounts []Account) []string {
 func openAIConfiguredCodexModelIDsForGroup(accounts []Account, group *Group) []string {
 	models := supplementUnmappedOpenAIModels(accounts, openAIConfiguredCodexModelIDs(accounts))
 	if group == nil || !group.ModelAllowlistEnabled() {
-		return models
+		return filterRetiredOpenAIModelIDs(accounts, models)
 	}
 
 	seen := make(map[string]struct{}, len(models)+len(group.ModelAllowlist.Models))
@@ -329,7 +323,7 @@ func openAIConfiguredCodexModelIDsForGroup(accounts []Account, group *Group) []s
 		}
 	}
 	sort.Strings(models)
-	return models
+	return filterRetiredOpenAIModelIDs(accounts, models)
 }
 
 const (
@@ -908,6 +902,19 @@ func buildCodexModelsManifestForAccounts(
 	compositeRoutes []CompositeModelRoute,
 	compositeRoutesAvailable bool,
 ) ([]byte, error) {
+	if effectivePlatform == PlatformOpenAI {
+		modelIDs = filterRetiredOpenAIModelIDs(accounts, modelIDs)
+	} else if effectivePlatform == PlatformComposite {
+		filtered := make([]string, 0, len(modelIDs))
+		for _, modelID := range modelIDs {
+			platform, target, resolved := resolveCodexCompositeModelTarget(modelID, accounts, compositeRoutes, compositeRoutesAvailable)
+			if resolved && platform == PlatformOpenAI && openAIModelRetiredForAccounts(accounts, target) {
+				continue
+			}
+			filtered = append(filtered, modelID)
+		}
+		modelIDs = filtered
+	}
 	imageInputModels := make(map[string]bool, len(modelIDs))
 	searchToolModels := make(map[string]bool, len(modelIDs))
 	metadataModels := codexCatalogMetadataModels(

backend/internal/service/openai_compact_fallback.go

@@ -57,6 +57,9 @@ func (s *OpenAIGatewayService) resolveOpenAICompactFallbackModel(account *Accoun
 	if account != nil {
 		if mapped, matched := account.ResolveCompactMappedModel(requestedModel); matched {
 			if mapped = strings.TrimSpace(mapped); mapped != "" {
+				if isRetiredOpenAISubscriptionModel(account, mapped) {
+					return ""
+				}
 				return mapped
 			}
 		}
@@ -68,7 +71,11 @@ func (s *OpenAIGatewayService) resolveOpenAICompactFallbackModel(account *Accoun
 	if fallback == "" {
 		return ""
 	}
-	return strings.TrimSpace(resolveOpenAIAccountUpstreamModelForRequest(account, fallback, false))
+	resolved := strings.TrimSpace(resolveOpenAIAccountUpstreamModelForRequest(account, fallback, false))
+	if isRetiredOpenAISubscriptionModel(account, resolved) {
+		return ""
+	}
+	return resolved
 }
 
 func isOpenAICompactModelFailure(statusCode int, upstreamMsg string, upstreamBody []byte) bool {

backend/internal/service/openai_gateway_model_availability.go

@@ -56,6 +56,9 @@ func (s *OpenAIGatewayService) DiagnoseModelAvailabilityForPlatform(
 	diag := ModelAvailabilityDiagnosis{}
 	for i := range accounts {
 		diag.HasAccountsInPool = true
+		if isRetiredOpenAISubscriptionModel(&accounts[i], resolveOpenAIAccountUpstreamModelForRequest(&accounts[i], requestedModel, false)) {
+			diag.HasRetiredSubscriptionModel = true
+		}
 		// Mirrors the per-candidate filter used during account selection
 		// (openai_account_scheduler.isAccountRequestCompatible): empty
 		// model_mapping accepts everything; otherwise the explicit / wildcard

backend/internal/service/openai_gateway_scheduling.go

@@ -440,7 +440,7 @@ func openAICompatibleAccountEligibilityFailureReasonBeforeProfit(ctx context.Con
 			return "quota_auto_pause"
 		}
 	}
-	if requestedModel != "" && !account.IsModelSupported(requestedModel) {
+	if requestedModel != "" && !supportsOpenAIRequestModel(account, requestedModel, requireCompact) {
 		return "model_not_supported"
 	}
 	if !account.SupportsOpenAIEndpointCapability(requiredCapability) {

backend/internal/service/openai_model_retirement.go

@@ -0,0 +1,90 @@
+package service
+
+import (
+	"encoding/json"
+	"strings"
+)
+
+// GPT-5.5 retired from Codex with ChatGPT sign-in on 2026-10-14 at
+// 19:00 UTC. API-key upstreams remain supported. Do not infer upstream
+// eligibility from the API key a client uses to authenticate to this gateway.
+// https://learn.chatgpt.com/docs/models#gpt-55-retirement
+func isRetiredOpenAISubscriptionModel(account *Account, upstreamModel string) bool {
+	if account == nil || !account.IsOpenAI() || (!account.IsOpenAIOAuthLike() && !account.IsShadow()) {
+		return false
+	}
+	model := canonicalizeOpenAIModelAliasSpelling(upstreamModel)
+	return model == "gpt-5.5" || strings.HasPrefix(model, "gpt-5.5-")
+}
+
+// Only remove entries blocked by retirement. Unknown models and other platforms
+// retain their existing listing policy. An explicitly mapped replacement is
+// allowed, but a public alias targeting retired GPT-5.5 is not.
+func openAIModelRetiredForAccounts(accounts []Account, modelID string) bool {
+	retired := false
+	for i := range accounts {
+		account := &accounts[i]
+		if !account.IsOpenAI() {
+			continue
+		}
+		target := resolveOpenAIAccountUpstreamModelForRequest(account, modelID, false)
+		if isRetiredOpenAISubscriptionModel(account, target) {
+			retired = true
+		} else if account.IsModelSupported(modelID) {
+			return false
+		}
+	}
+	return retired
+}
+
+func filterRetiredOpenAIModelIDs(accounts []Account, models []string) []string {
+	filtered := make([]string, 0, len(models))
+	for _, model := range models {
+		if !openAIModelRetiredForAccounts(accounts, model) {
+			filtered = append(filtered, model)
+		}
+	}
+	return filtered
+}
+
+// Apply after account/group mappings, including on cached upstream catalogs,
+// and before the final client ETag is calculated. Preserve unknown fields.
+func filterRetiredOpenAIModelsBody(body []byte, accounts []Account, codex bool) ([]byte, bool, error) {
+	field, idField := "data", "id"
+	if codex {
+		field, idField = "models", "slug"
+	}
+	envelope, entries, err := modelCatalogEntries(body, field)
+	if err != nil {
+		return nil, false, err
+	}
+	filtered := make([]json.RawMessage, 0, len(entries))
+	for _, raw := range entries {
+		var entry map[string]json.RawMessage
+		var id string
+		if json.Unmarshal(raw, &entry) == nil {
+			_ = json.Unmarshal(entry[idField], &id)
+		}
+		if !openAIModelRetiredForAccounts(accounts, id) {
+			filtered = append(filtered, raw)
+		}
+	}
+	if len(filtered) == len(entries) {
+		return body, false, nil
+	}
+	envelope[field], err = json.Marshal(filtered)
+	if err != nil {
+		return nil, false, err
+	}
+	encoded, err := json.Marshal(envelope)
+	return encoded, true, err
+}
+
+// Compact-only administrator mappings are evaluated against their actual
+// target, without treating an old client-visible name as a retired target.
+func supportsOpenAIRequestModel(account *Account, requestedModel string, requireCompact bool) bool {
+	if isRetiredOpenAISubscriptionModel(account, resolveOpenAIAccountUpstreamModelForRequest(account, requestedModel, requireCompact)) {
+		return false
+	}
+	return account.isModelMappingSupported(requestedModel)
+}

backend/internal/service/openai_model_retirement_test.go

@@ -0,0 +1,174 @@
+package service
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/Wei-Shaw/sub2api/internal/config"
+	"github.com/stretchr/testify/require"
+	"github.com/tidwall/gjson"
+)
+
+func TestGPT55RetirementModelSupport(t *testing.T) {
+	for _, typ := range []string{AccountTypeOAuth, AccountTypeSetupToken, AccountTypeAPIKey} {
+		for _, passthrough := range []bool{false, true} {
+			t.Run(typ+"/passthrough="+map[bool]string{true: "true", false: "false"}[passthrough], func(t *testing.T) {
+				account := &Account{Platform: PlatformOpenAI, Type: typ, Extra: map[string]any{"openai_passthrough": passthrough}}
+				for _, model := range []string{"gpt-5.5", "openai/gpt-5.5-high", "gpt-5.5-2026-04-23", "GPT_5.5", "gpt-5.5-openai-compact"} {
+					require.Equal(t, typ == AccountTypeAPIKey, account.IsModelSupported(model), model)
+				}
+				require.True(t, account.IsModelSupported("gpt-6.1-sol"))
+			})
+		}
+	}
+	for _, mapping := range []map[string]any{
+		{"legacy": "gpt-5.5"}, {"legacy*": "gpt-5.5"},
+	} {
+		account := &Account{Platform: PlatformOpenAI, Type: AccountTypeOAuth, Credentials: map[string]any{"model_mapping": mapping}}
+		require.False(t, account.IsModelSupported("legacy"))
+	}
+	account := &Account{Platform: PlatformOpenAI, Type: AccountTypeOAuth, Credentials: map[string]any{"model_mapping": map[string]any{"gpt-5.5": "gpt-6.1-sol"}}}
+	require.True(t, account.IsModelSupported("gpt-5.5"), "explicit administrator replacement remains authoritative")
+	account.Type = AccountTypeAPIKey
+	require.True(t, account.IsModelSupported("gpt-5.5"))
+	parent := int64(3)
+	shadow := &Account{Platform: PlatformOpenAI, Type: AccountTypeAPIKey, ParentAccountID: &parent}
+	require.False(t, shadow.IsModelSupported("gpt-5.5"))
+	require.False(t, isRetiredOpenAISubscriptionModel(&Account{Platform: PlatformAnthropic, Type: AccountTypeOAuth}, "gpt-5.5"))
+	require.False(t, isRetiredOpenAISubscriptionModel(account, "gpt-5.50"))
+}
+
+func TestGPT55RetirementCatalogs(t *testing.T) {
+	oauth := Account{ID: 1, Platform: PlatformOpenAI, Type: AccountTypeOAuth}
+	api := Account{ID: 2, Platform: PlatformOpenAI, Type: AccountTypeAPIKey}
+	group := &Group{ID: 1, Platform: PlatformOpenAI}
+	for _, tc := range []struct {
+		name      string
+		accounts  []Account
+		wantGPT55 bool
+	}{
+		{"oauth", []Account{oauth}, false}, {"api", []Account{api}, true}, {"mixed", []Account{oauth, api}, true},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			repo := codexModelsVisibilityAccountRepo{byGroup: map[int64][]Account{1: tc.accounts}}
+			gateway := &GatewayService{accountRepo: repo}
+			models := gateway.GetAvailableModels(context.Background(), &group.ID, PlatformOpenAI)
+			if models != nil {
+				require.Equal(t, tc.wantGPT55, containsModelID(models, "gpt-5.5"))
+			}
+			body, err := buildCodexModelsManifestForAccounts(PlatformOpenAI, []string{"gpt-5.5", "gpt-6.1-sol"}, tc.accounts, group, nil, true)
+			require.NoError(t, err)
+			require.Equal(t, tc.wantGPT55, containsManifestModel(body, "gpt-5.5"))
+			// A stale/pinned upstream body must be filtered before evaluating its old ETag.
+			original := []byte(`{"models":[{"slug":"gpt-5.5","unknown":1},{"slug":"gpt-6.1-sol","unknown":2}],"unknown_top":3}`)
+			etag := CodexModelsManifestETag(original)
+			manifest := &OpenAIModelsResponse{Body: original, ETag: etag}
+			service := &OpenAIGatewayService{accountRepo: repo}
+			require.NoError(t, service.MergeGroupConfiguredCodexModels(context.Background(), group, manifest, etag))
+			if !tc.wantGPT55 {
+				require.False(t, manifest.NotModified)
+				require.NotEqual(t, etag, manifest.ETag)
+				require.False(t, containsManifestModel(manifest.Body, "gpt-5.5"))
+				require.Equal(t, int64(3), gjson.GetBytes(manifest.Body, "unknown_top").Int())
+				require.Equal(t, int64(2), gjson.GetBytes(manifest.Body, "models.0.unknown").Int())
+			}
+		})
+	}
+	// All configured entries retired: plain discovery must remain an authoritative empty list.
+	oauth.Credentials = map[string]any{"model_mapping": map[string]any{"gpt-5.5": "gpt-5.5"}}
+	repo := codexModelsVisibilityAccountRepo{byGroup: map[int64][]Account{1: {oauth}}}
+	models := (&GatewayService{accountRepo: repo}).GetAvailableModels(context.Background(), &group.ID, PlatformOpenAI)
+	require.NotNil(t, models)
+	require.Empty(t, models)
+}
+
+func containsModelID(models []string, id string) bool {
+	for _, model := range models {
+		if model == id {
+			return true
+		}
+	}
+	return false
+}
+func containsManifestModel(body []byte, id string) bool {
+	for _, m := range gjson.GetBytes(body, "models").Array() {
+		if m.Get("slug").String() == id {
+			return true
+		}
+	}
+	return false
+}
+
+func TestGPT55RetirementAccountProjection(t *testing.T) {
+	body := []byte(`{"object":"list","data":[{"id":"gpt-5.5"},{"id":"gpt-6.1-sol","unknown":true}],"unknown_top":true}`)
+	for _, typ := range []string{AccountTypeOAuth, AccountTypeAPIKey} {
+		account := &Account{Platform: PlatformOpenAI, Type: typ}
+		got, err := projectAccountModelsBody(body, account, nil, false)
+		require.NoError(t, err)
+		require.Equal(t, typ == AccountTypeAPIKey, strings.Contains(string(got), "gpt-5.5"))
+		require.True(t, gjson.GetBytes(got, "unknown_top").Bool())
+		require.True(t, json.Valid(got))
+	}
+}
+
+func TestGPT55RetirementCompactFallbackKeepsSelectedModel(t *testing.T) {
+	for _, passthrough := range []bool{false, true} {
+		account := &Account{ID: 1, Platform: PlatformOpenAI, Type: AccountTypeOAuth, Concurrency: 1,
+			Credentials: map[string]any{"access_token": "test-token"}, Extra: map[string]any{"openai_passthrough": passthrough}}
+		upstream := &httpUpstreamRecorder{resp: &http.Response{StatusCode: http.StatusOK, Header: http.Header{"Content-Type": []string{"application/json"}}, Body: io.NopCloser(strings.NewReader(`{"id":"compact","output":[],"usage":{"input_tokens":1,"output_tokens":1}}`))}}
+		svc := &OpenAIGatewayService{cfg: &config.Config{Gateway: config.GatewayConfig{OpenAICompactModel: "gpt-5.5"}}, httpUpstream: upstream}
+		require.Empty(t, svc.resolveOpenAICompactFallbackModel(account, "gpt-6.1-sol"))
+		c := newOpenAICompactFallbackTestContext(t, "/v1/responses/compact")
+		_, err := svc.Forward(context.Background(), c, account, []byte(`{"model":"gpt-6.1-sol","input":[],"instructions":"compact","stream":false}`))
+		require.NoError(t, err)
+		require.Equal(t, "gpt-6.1-sol", gjson.GetBytes(upstream.lastBody, "model").String())
+		account.Type = AccountTypeAPIKey
+		require.Equal(t, "gpt-5.5", svc.resolveOpenAICompactFallbackModel(account, "gpt-6.1-sol"))
+	}
+}
+
+func TestGPT55RetirementSchedulerAndDiagnosis(t *testing.T) {
+	ctx := context.Background()
+	groupID := int64(1)
+	oauth := Account{ID: 1, Platform: PlatformOpenAI, Type: AccountTypeOAuth, Status: StatusActive, Schedulable: true}
+	api := Account{ID: 2, Platform: PlatformOpenAI, Type: AccountTypeAPIKey, Status: StatusActive, Schedulable: true}
+	for _, typ := range []string{AccountTypeOAuth, AccountTypeSetupToken, AccountTypeAPIKey} {
+		account := oauth
+		account.Type = typ
+		scheduler := &defaultOpenAIAccountScheduler{}
+		ok, _ := scheduler.isAccountRequestCompatibleReason(ctx, &account, OpenAIAccountScheduleRequest{RequestedModel: "gpt-5.5"})
+		require.Equal(t, typ == AccountTypeAPIKey, ok)
+		reason := openAICompatibleAccountEligibilityFailureReasonBeforeProfit(ctx, &account, PlatformOpenAI, "gpt-5.5", false, "")
+		require.Equal(t, typ == AccountTypeAPIKey, reason == "")
+	}
+	oauth.Credentials = map[string]any{"compact_model_mapping": map[string]any{"gpt-6.1-sol": "gpt-5.5"}}
+	scheduler := &defaultOpenAIAccountScheduler{}
+	ok, reason := scheduler.isAccountRequestCompatibleReason(ctx, &oauth, OpenAIAccountScheduleRequest{RequestedModel: "gpt-6.1-sol", RequireCompact: true})
+	require.False(t, ok)
+	require.Equal(t, "model_not_supported", reason)
+	svc := &OpenAIGatewayService{cfg: &config.Config{Gateway: config.GatewayConfig{OpenAICompactModel: "gpt-6.1-sol"}}}
+	require.Empty(t, svc.resolveOpenAICompactFallbackModel(&oauth, "gpt-6.1-sol"), "native compact retries must not use a retired explicit target")
+	oauth.Credentials = map[string]any{"compact_model_mapping": map[string]any{"gpt-5.5": "gpt-6.1-sol"}}
+	ok, _ = scheduler.isAccountRequestCompatibleReason(ctx, &oauth, OpenAIAccountScheduleRequest{RequestedModel: "gpt-5.5", RequireCompact: true})
+	require.True(t, ok, "an explicit compact replacement remains usable")
+	for _, accounts := range [][]Account{{oauth}, {oauth, api}} {
+		svc := &OpenAIGatewayService{accountRepo: codexModelsVisibilityAccountRepo{byGroup: map[int64][]Account{groupID: accounts}}}
+		diagnosis := svc.DiagnoseModelAvailabilityForPlatform(ctx, &groupID, "gpt-5.5", PlatformOpenAI)
+		require.True(t, diagnosis.HasAccountsInPool)
+		require.True(t, diagnosis.HasRetiredSubscriptionModel)
+		require.Equal(t, len(accounts) == 2, diagnosis.HasModelSupport)
+	}
+}
+
+func TestGPT55RetirementEmptyListingSource(t *testing.T) {
+	// A configured alias targeting retired GPT-5.5 must not reappear in a generated catalog.
+	account := Account{Platform: PlatformOpenAI, Type: AccountTypeOAuth, Credentials: map[string]any{"model_mapping": map[string]any{"legacy": "gpt-5.5"}}}
+	require.Empty(t, openAIConfiguredCodexModelIDsForGroup([]Account{account}, nil))
+	body, err := buildCodexModelsManifestForAccounts(PlatformComposite, []string{"gpt-5.5", "gpt-6.1-sol"}, []Account{account}, nil, nil, true)
+	require.NoError(t, err)
+	require.False(t, containsManifestModel(body, "gpt-5.5"))
+}

backend/internal/service/openai_models_list.go

@@ -165,6 +165,11 @@ func standardOpenAIModelsBody(body []byte, fromManifest bool) ([]byte, error) {
 // representations while retaining the source entry's metadata. It never changes
 // the shared response and never synthesizes models absent from this account.
 func projectAccountModelsBody(body []byte, account *Account, group *Group, codex bool) ([]byte, error) {
+	filtered, _, err := filterRetiredOpenAIModelsBody(body, []Account{*account}, codex)
+	if err != nil {
+		return nil, err
+	}
+	body = filtered
 	if account.IsOpenAIPassthroughEnabled() || len(account.GetModelMapping()) == 0 {
 		return body, nil
 	}

backend/internal/service/openai_ws_forwarder_support.go

@@ -571,7 +571,7 @@ func (s *OpenAIGatewayService) resolveAccountByPreviousResponseIDForCapability(
 		_ = store.DeleteResponseAccount(ctx, derefGroupID(groupID), responseID)
 		return 0, nil, "", nil
 	}
-	if requestedModel != "" && !account.IsModelSupported(requestedModel) {
+	if requestedModel != "" && !supportsOpenAIRequestModel(account, requestedModel, requireCompact) {
 		return 0, nil, "", nil
 	}
 	if !account.SupportsOpenAIEndpointCapability(requiredCapability) {
@@ -610,7 +610,7 @@ func (s *OpenAIGatewayService) resolveAccountByPreviousResponseIDForCapability(
 			_ = store.DeleteResponseAccount(ctx, derefGroupID(groupID), responseID)
 			return 0, nil, "", nil
 		}
-		if requestedModel != "" && !latest.IsModelSupported(requestedModel) {
+		if requestedModel != "" && !supportsOpenAIRequestModel(latest, requestedModel, requireCompact) {
 			return 0, nil, "", nil
 		}
 		if !latest.SupportsOpenAIEndpointCapability(requiredCapability) {

deploy/config.example.yaml

@@ -324,6 +324,8 @@ gateway:
   # OpenAI /responses/compact 上游模型（默认 gpt-5.5）。
   # Use this to avoid compact failures when newer models are not yet supported by the compact endpoint.
   # 当 compact 端点暂未支持更新模型时，可通过这里降级规避失败。
+  # GPT-5.5 is API-only after its ChatGPT Codex retirement; subscription
+  # requests skip this retired fallback and keep their selected model.
   openai_compact_model: "gpt-5.5"
   # ChatGPT Frameless Live 单会话硬上限（秒）。
   live:

docs/OPENAI_GPT55_RETIREMENT.md

@@ -0,0 +1,40 @@
+# GPT-5.5 retirement on ChatGPT-backed Codex accounts
+
+OpenAI retired GPT-5.5 from Codex with ChatGPT sign-in on October 14,
+2026 at 19:00 UTC (October 15 at 03:00 in Asia/Shanghai). Official API access
+is unaffected. See the [official migration notice](https://learn.chatgpt.com/docs/models#gpt-55-retirement).
+
+Sub2API applies this distinction to the upstream account, not the key used by
+clients to authenticate to Sub2API:
+
+- OpenAI OAuth and SetupToken accounts, including credential shadows, cannot
+  serve GPT-5.5. Normal, sticky, and compact scheduling exclude these targets.
+- API-key accounts retain GPT-5.5 support. In mixed groups, only eligible API-key
+  upstreams can serve it. Their actual model availability remains authoritative.
+- Public model lists and Codex catalogs omit models whose targets are retired on
+  the group's ChatGPT accounts and have no supporting API-key account. This also
+  filters stale/pinned catalog entries before calculating the client ETag.
+- Explicit administrator mappings to a supported replacement remain valid.
+  Aliases mapped *to* GPT-5.5 are excluded from ChatGPT account routing.
+- Unsupported requests return the existing `model_not_found` error with migration
+  guidance when the availability diagnosis identifies a retired subscription
+  target. Client chat requests are not silently rewritten to a replacement.
+
+## Administrator migration
+
+Review group/account mappings, client defaults, custom agents and scheduled tasks
+that select GPT-5.5. OpenAI recommends GPT-6.1 Sol for eligible paid plans or
+GPT-6 Luna for Free/Go in the desktop app, subject to model availability. Check
+availability on the upstream account before selecting a replacement.
+
+The global `gateway.openai_compact_model` setting remains compatible with API-key
+upstreams. If that fallback resolves to retired GPT-5.5 on a ChatGPT account, it
+is not applied; compact requests keep their selected model. A compact-only
+account mapping targeting retired GPT-5.5 is ineligible for scheduling: update
+that explicit mapping. No stored settings are automatically rewritten.
+
+Changing the public registry, deleting GPT-5.5 pricing/history, or globally
+mapping GPT-5.5 to a new model is unnecessary and would affect valid API usage.
+
+Regression tests use local fixtures and stub upstream responses. They do not
+establish real subscription access to a replacement model.