diff --git a/ui/src/components/cliproxy/provider-model-selector.tsx b/ui/src/components/cliproxy/provider-model-selector.tsx
index 405c9f19..e6607c19 100644
--- a/ui/src/components/cliproxy/provider-model-selector.tsx
+++ b/ui/src/components/cliproxy/provider-model-selector.tsx
@@ -18,15 +18,22 @@ import {
   SelectValue,
 } from '@/components/ui/select';
 import { Skeleton } from '@/components/ui/skeleton';
+import { Switch } from '@/components/ui/switch';
 import type { CliproxyProviderRoutingHints } from '@/lib/api-client';
 import type { CodexEffort, CodexServiceTier } from '@/lib/codex-effort';
 import {
+  applyCodexServiceTierSuffix,
   getCodexEffortDisplay,
   getCodexEffortVariants,
   parseCodexEffort,
   parseCodexServiceTier,
+  stripCodexEffortSuffix,
 } from '@/lib/codex-effort';
-import { getResolvedCatalogModels, getSupplementalCatalogModels } from '@/lib/model-catalogs';
+import {
+  findCatalogModel,
+  getResolvedCatalogModels,
+  getSupplementalCatalogModels,
+} from '@/lib/model-catalogs';
 import { getReasoningAdapter } from '@/lib/reasoning-control';
 import { cn } from '@/lib/utils';
 
@@ -586,6 +593,19 @@ export function FlexibleModelSelector({
     !selectableReasoningLevels.includes(currentReasoningLevel)
       ? [...selectableReasoningLevels, currentReasoningLevel]
       : selectableReasoningLevels;
+  const currentServiceTier = isCodexProvider ? parseCodexServiceTier(value) : undefined;
+  const selectedCodexBaseModel =
+    isCodexProvider && catalog && value
+      ? findCatalogModel(
+          catalog.provider,
+          stripCodexEffortSuffix(normalizeModelValue(value, routing)),
+          catalog
+        )
+      : undefined;
+  const showFastToggle =
+    isCodexProvider &&
+    (selectedCodexBaseModel?.codexServiceTiers?.includes('fast') === true ||
+      currentServiceTier === 'fast');
 
   return (
     <div className="space-y-1.5">
@@ -702,6 +722,19 @@ export function FlexibleModelSelector({
             </SelectContent>
           </Select>
         )}
+        {showFastToggle && (
+          <label className="flex h-9 shrink-0 items-center gap-1.5">
+            <Switch
+              checked={currentServiceTier === 'fast'}
+              onCheckedChange={(checked) => onChange(applyCodexServiceTierSuffix(value, checked))}
+              disabled={disabled || !value}
+              aria-label={t('providerModelSelector.fastTier')}
+            />
+            <span className="text-xs text-muted-foreground">
+              {t('providerModelSelector.fastTier')}
+            </span>
+          </label>
+        )}
       </div>
       {selectedRoutingHint ? (
         <div
diff --git a/ui/src/lib/codex-effort.ts b/ui/src/lib/codex-effort.ts
index ae00ba54..393b78af 100644
--- a/ui/src/lib/codex-effort.ts
+++ b/ui/src/lib/codex-effort.ts
@@ -66,6 +66,12 @@ export function applyCodexEffortSuffix(
   return [normalizedModelId, effort, parsed.serviceTier].filter(Boolean).join('-');
 }
 
+export function applyCodexServiceTierSuffix(modelId: string | undefined, enabled: boolean): string {
+  const parsed = parseCodexTuningSuffix(modelId);
+  if (!parsed.baseModel) return parsed.baseModel;
+  return [parsed.baseModel, parsed.effort, enabled ? 'fast' : undefined].filter(Boolean).join('-');
+}
+
 export function getCodexEffortVariants(
   modelId: string,
   maxEffort: CodexEffort | undefined,
diff --git a/ui/src/lib/i18n.ts b/ui/src/lib/i18n.ts
index e9d047c9..55d6ae6c 100644
--- a/ui/src/lib/i18n.ts
+++ b/ui/src/lib/i18n.ts
@@ -230,6 +230,7 @@ const resources = {
         codexFastVariants: 'Fast variants',
         effortLabel: 'Effort',
         effortAuto: 'Auto',
+        fastTier: 'Fast',
       },
       createAuthProfileDialog: {
         title: 'Create New Account',
@@ -2958,6 +2959,7 @@ const resources = {
         codexFastVariants: '快速变体',
         effortLabel: '推理强度',
         effortAuto: '自动',
+        fastTier: '快速',
       },
       createAuthProfileDialog: {
         title: '创建新账号',
@@ -5569,6 +5571,7 @@ const resources = {
         codexFastVariants: 'Biến thể nhanh',
         effortLabel: 'Mức suy luận',
         effortAuto: 'Tự động',
+        fastTier: 'Nhanh',
       },
       createAuthProfileDialog: {
         title: 'Tạo tài khoản mới',
@@ -8296,6 +8299,7 @@ const resources = {
         codexFastVariants: '高速バリアント',
         effortLabel: '推論レベル',
         effortAuto: '自動',
+        fastTier: '高速',
       },
       createAuthProfileDialog: {
         title: '新しいアカウントを作成',
@@ -11046,6 +11050,7 @@ const resources = {
         codexFastVariants: '빠른 변형',
         effortLabel: '추론 강도',
         effortAuto: '자동',
+        fastTier: '고속',
       },
       createAuthProfileDialog: {
         title: '새 계정 생성',
diff --git a/ui/tests/unit/ui/lib/codex-effort.test.ts b/ui/tests/unit/ui/lib/codex-effort.test.ts
index 7031d89f..a0f377be 100644
--- a/ui/tests/unit/ui/lib/codex-effort.test.ts
+++ b/ui/tests/unit/ui/lib/codex-effort.test.ts
@@ -1,6 +1,7 @@
 import { describe, expect, it } from 'vitest';
 import {
   applyCodexEffortSuffix,
+  applyCodexServiceTierSuffix,
   getCodexEffortDisplay,
   getCodexEffortVariants,
   getSelectableCodexEfforts,
@@ -111,6 +112,40 @@ describe('codex effort helpers', () => {
   });
 });
 
+describe('applyCodexServiceTierSuffix', () => {
+  it('adds the fast tier while preserving the effort suffix', () => {
+    expect(applyCodexServiceTierSuffix('gpt-5.4-high', true)).toBe('gpt-5.4-high-fast');
+  });
+
+  it('removes only the fast tier', () => {
+    expect(applyCodexServiceTierSuffix('gpt-5.4-high-fast', false)).toBe('gpt-5.4-high');
+    expect(applyCodexServiceTierSuffix('gpt-5.4-fast', false)).toBe('gpt-5.4');
+  });
+
+  it('preserves routing prefixes', () => {
+    expect(applyCodexServiceTierSuffix('codex/gpt-5.6-sol', true)).toBe('codex/gpt-5.6-sol-fast');
+  });
+
+  it('is idempotent and safe on empty input', () => {
+    expect(applyCodexServiceTierSuffix('gpt-5.4-fast', true)).toBe('gpt-5.4-fast');
+    expect(applyCodexServiceTierSuffix('gpt-5.4', false)).toBe('gpt-5.4');
+    expect(applyCodexServiceTierSuffix(undefined, true)).toBe('');
+    expect(applyCodexServiceTierSuffix('', true)).toBe('');
+  });
+
+  it('composes with applyCodexEffortSuffix in both orders', () => {
+    expect(applyCodexEffortSuffix(applyCodexServiceTierSuffix('gpt-5.4', true), 'high')).toBe(
+      'gpt-5.4-high-fast'
+    );
+    expect(applyCodexServiceTierSuffix(applyCodexEffortSuffix('gpt-5.4', 'high'), true)).toBe(
+      'gpt-5.4-high-fast'
+    );
+    expect(
+      applyCodexEffortSuffix(applyCodexServiceTierSuffix('gpt-5.4-high-fast', false), 'low')
+    ).toBe('gpt-5.4-low');
+  });
+});
+
 describe('getSelectableCodexEfforts', () => {
   it('returns the explicit efforts list when provided', () => {
     expect(getSelectableCodexEfforts('xhigh', ['low', 'medium', 'high', 'xhigh'])).toEqual([