diff --git a/backend/internal/service/openai_codex_transform.go b/backend/internal/service/openai_codex_transform.go
index dcc30fc1..264bdf95 100644
--- a/backend/internal/service/openai_codex_transform.go
+++ b/backend/internal/service/openai_codex_transform.go
@@ -90,17 +90,11 @@ func applyCodexOAuthTransform(reqBody map[string]any) codexTransformResult {
 		result.NormalizedModel = normalizedModel
 	}
 
-	// 续链场景强制启用 store；非续链仍按原策略强制关闭存储。
-	if needsToolContinuation {
-		if v, ok := reqBody["store"].(bool); !ok || !v {
-			reqBody["store"] = true
-			result.Modified = true
-		}
-	} else {
-		if v, ok := reqBody["store"].(bool); !ok || v {
-			reqBody["store"] = false
-			result.Modified = true
-		}
+	// OAuth 走 ChatGPT internal API 时，store 必须为 false；显式 true 也会强制覆盖。
+	// 避免上游返回 "Store must be set to false"。
+	if v, ok := reqBody["store"].(bool); !ok || v {
+		reqBody["store"] = false
+		result.Modified = true
 	}
 	if v, ok := reqBody["stream"].(bool); !ok || !v {
 		reqBody["stream"] = true
diff --git a/backend/internal/service/openai_codex_transform_test.go b/backend/internal/service/openai_codex_transform_test.go
index 9663229f..0ff9485a 100644
--- a/backend/internal/service/openai_codex_transform_test.go
+++ b/backend/internal/service/openai_codex_transform_test.go
@@ -11,7 +11,7 @@ import (
 )
 
 func TestApplyCodexOAuthTransform_ToolContinuationPreservesInput(t *testing.T) {
-	// 续链场景：保留 item_reference 与 id，并启用 store。
+	// 续链场景：保留 item_reference 与 id，但不再强制 store=true。
 	setupCodexCache(t)
 
 	reqBody := map[string]any{
@@ -25,9 +25,10 @@ func TestApplyCodexOAuthTransform_ToolContinuationPreservesInput(t *testing.T) {
 
 	applyCodexOAuthTransform(reqBody)
 
+	// 未显式设置 store=true，默认为 false。
 	store, ok := reqBody["store"].(bool)
 	require.True(t, ok)
-	require.True(t, store)
+	require.False(t, store)
 
 	input, ok := reqBody["input"].([]any)
 	require.True(t, ok)
@@ -45,8 +46,8 @@ func TestApplyCodexOAuthTransform_ToolContinuationPreservesInput(t *testing.T) {
 	require.Equal(t, "o1", second["id"])
 }
 
-func TestApplyCodexOAuthTransform_ToolContinuationForcesStoreTrue(t *testing.T) {
-	// 续链场景：显式 store=false 也会被强制为 true。
+func TestApplyCodexOAuthTransform_ExplicitStoreFalsePreserved(t *testing.T) {
+	// 续链场景：显式 store=false 不再强制为 true，保持 false。
 	setupCodexCache(t)
 
 	reqBody := map[string]any{
@@ -62,16 +63,35 @@ func TestApplyCodexOAuthTransform_ToolContinuationForcesStoreTrue(t *testing.T)
 
 	store, ok := reqBody["store"].(bool)
 	require.True(t, ok)
-	require.True(t, store)
+	require.False(t, store)
 }
 
-func TestApplyCodexOAuthTransform_NonContinuationForcesStoreFalseAndStripsIDs(t *testing.T) {
-	// 非续链场景：强制 store=false，并移除 input 中的 id。
+func TestApplyCodexOAuthTransform_ExplicitStoreTrueForcedFalse(t *testing.T) {
+	// 显式 store=true 也会强制为 false。
 	setupCodexCache(t)
 
 	reqBody := map[string]any{
 		"model": "gpt-5.1",
 		"store": true,
+		"input": []any{
+			map[string]any{"type": "function_call_output", "call_id": "call_1"},
+		},
+		"tool_choice": "auto",
+	}
+
+	applyCodexOAuthTransform(reqBody)
+
+	store, ok := reqBody["store"].(bool)
+	require.True(t, ok)
+	require.False(t, store)
+}
+
+func TestApplyCodexOAuthTransform_NonContinuationDefaultsStoreFalseAndStripsIDs(t *testing.T) {
+	// 非续链场景：未设置 store 时默认 false，并移除 input 中的 id。
+	setupCodexCache(t)
+
+	reqBody := map[string]any{
+		"model": "gpt-5.1",
 		"input": []any{
 			map[string]any{"type": "text", "id": "t1", "text": "hi"},
 		},
diff --git a/frontend/src/components/admin/user/UserBalanceModal.vue b/frontend/src/components/admin/user/UserBalanceModal.vue
index 61d4785e..c669c2a5 100644
--- a/frontend/src/components/admin/user/UserBalanceModal.vue
+++ b/frontend/src/components/admin/user/UserBalanceModal.vue
@@ -3,14 +3,17 @@
     <form v-if="user" id="balance-form" @submit.prevent="handleBalanceSubmit" class="space-y-5">
       <div class="flex items-center gap-3 rounded-xl bg-gray-50 p-4 dark:bg-dark-700">
         <div class="flex h-10 w-10 items-center justify-center rounded-full bg-primary-100"><span class="text-lg font-medium text-primary-700">{{ user.email.charAt(0).toUpperCase() }}</span></div>
-        <div class="flex-1"><p class="font-medium text-gray-900">{{ user.email }}</p><p class="text-sm text-gray-500">{{ t('admin.users.currentBalance') }}: ${{ user.balance.toFixed(2) }}</p></div>
+        <div class="flex-1"><p class="font-medium text-gray-900">{{ user.email }}</p><p class="text-sm text-gray-500">{{ t('admin.users.currentBalance') }}: ${{ formatBalance(user.balance) }}</p></div>
       </div>
       <div>
         <label class="input-label">{{ operation === 'add' ? t('admin.users.depositAmount') : t('admin.users.withdrawAmount') }}</label>
-        <div class="relative"><div class="absolute left-3 top-1/2 -translate-y-1/2 font-medium text-gray-500">$</div><input v-model.number="form.amount" type="number" step="0.01" min="0.01" required class="input pl-8" /></div>
+        <div class="relative flex gap-2">
+          <div class="relative flex-1"><div class="absolute left-3 top-1/2 -translate-y-1/2 font-medium text-gray-500">$</div><input v-model.number="form.amount" type="number" step="any" min="0" required class="input pl-8" /></div>
+          <button v-if="operation === 'subtract'" type="button" @click="fillAllBalance" class="btn btn-secondary whitespace-nowrap">{{ t('admin.users.withdrawAll') }}</button>
+        </div>
       </div>
       <div><label class="input-label">{{ t('admin.users.notes') }}</label><textarea v-model="form.notes" rows="3" class="input"></textarea></div>
-      <div v-if="form.amount > 0" class="rounded-xl border border-blue-200 bg-blue-50 p-4"><div class="flex items-center justify-between text-sm"><span>{{ t('admin.users.newBalance') }}:</span><span class="font-bold">${{ calculateNewBalance().toFixed(2) }}</span></div></div>
+      <div v-if="form.amount > 0" class="rounded-xl border border-blue-200 bg-blue-50 p-4"><div class="flex items-center justify-between text-sm"><span>{{ t('admin.users.newBalance') }}:</span><span class="font-bold">${{ formatBalance(calculateNewBalance()) }}</span></div></div>
     </form>
     <template #footer>
       <div class="flex justify-end gap-3">
@@ -35,11 +38,30 @@ const emit = defineEmits(['close', 'success']); const { t } = useI18n(); const a
 const submitting = ref(false); const form = reactive({ amount: 0, notes: '' })
 watch(() => props.show, (v) => { if(v) { form.amount = 0; form.notes = '' } })
 
+// 格式化余额：显示完整精度，去除尾部多余的0
+const formatBalance = (value: number) => {
+  if (value === 0) return '0.00'
+  // 最多保留8位小数，去除尾部的0
+  const formatted = value.toFixed(8).replace(/\.?0+$/, '')
+  // 确保至少有2位小数
+  const parts = formatted.split('.')
+  if (parts.length === 1) return formatted + '.00'
+  if (parts[1].length === 1) return formatted + '0'
+  return formatted
+}
+
+// 填入全部余额
+const fillAllBalance = () => {
+  if (props.user) {
+    form.amount = props.user.balance
+  }
+}
+
 const calculateNewBalance = () => {
   if (!props.user) return 0
   const result = props.operation === 'add' ? props.user.balance + form.amount : props.user.balance - form.amount
   // 避免浮点数精度问题导致的 -0.00 显示
-  return result === 0 || Object.is(result, -0) ? 0 : result
+  return Math.abs(result) < 1e-10 ? 0 : result
 }
 const handleBalanceSubmit = async () => {
   if (!props.user) return
@@ -47,10 +69,8 @@ const handleBalanceSubmit = async () => {
     appStore.showError(t('admin.users.amountRequired'))
     return
   }
-  // 使用小数点后两位精度比较，避免浮点数精度问题
-  const amount = Math.round(form.amount * 100) / 100
-  const balance = Math.round(props.user.balance * 100) / 100
-  if (props.operation === 'subtract' && amount > balance) {
+  // 退款时验证金额不超过实际余额
+  if (props.operation === 'subtract' && form.amount > props.user.balance) {
     appStore.showError(t('admin.users.insufficientBalance'))
     return
   }
diff --git a/frontend/src/i18n/locales/en.ts b/frontend/src/i18n/locales/en.ts
index bb2c05bc..69a56fa5 100644
--- a/frontend/src/i18n/locales/en.ts
+++ b/frontend/src/i18n/locales/en.ts
@@ -727,6 +727,7 @@ export default {
       withdraw: 'Withdraw',
       depositAmount: 'Deposit Amount',
       withdrawAmount: 'Withdraw Amount',
+      withdrawAll: 'All',
       currentBalance: 'Current Balance',
       depositNotesPlaceholder:
         'e.g., New user registration bonus, promotional credit, compensation, etc.',
diff --git a/frontend/src/i18n/locales/zh.ts b/frontend/src/i18n/locales/zh.ts
index dcb0a812..ac50e20b 100644
--- a/frontend/src/i18n/locales/zh.ts
+++ b/frontend/src/i18n/locales/zh.ts
@@ -783,6 +783,7 @@ export default {
       withdraw: '退款',
       depositAmount: '充值金额',
       withdrawAmount: '退款金额',
+      withdrawAll: '全部',
       depositNotesPlaceholder: '例如：新用户注册奖励、活动充值、补偿充值等',
       withdrawNotesPlaceholder: '例如：服务问题退款、错误充值退回、账户注销退款等',
       notesOptional: '备注为可选项，有助于未来查账',