diff --git a/frontend/src/components/payment/SubscriptionPlanCard.vue b/frontend/src/components/payment/SubscriptionPlanCard.vue
index dd9d63ecc0..dbc084f821 100644
--- a/frontend/src/components/payment/SubscriptionPlanCard.vue
+++ b/frontend/src/components/payment/SubscriptionPlanCard.vue
@@ -3,20 +3,20 @@
     :class="[
       'group relative flex flex-col overflow-hidden rounded-2xl border transition-all',
       'hover:shadow-xl hover:-translate-y-0.5',
-      cardBorderClass,
+      borderClass,
       'bg-white dark:bg-dark-800',
     ]"
   >
     <!-- Colored top accent bar -->
-    <div :class="['h-1.5', accentBarClass]" />
+    <div :class="['h-1.5', accentClass]" />
 
     <div class="flex flex-1 flex-col p-5">
       <!-- Header: name + platform badge -->
       <div class="mb-4">
         <div class="flex items-center gap-2">
           <h3 class="text-base font-bold text-gray-900 dark:text-white">{{ plan.name }}</h3>
-          <span :class="['rounded-full px-2 py-0.5 text-[11px] font-medium', platformBadgeClass]">
-            {{ platformLabel }}
+          <span :class="['rounded-full px-2 py-0.5 text-[11px] font-medium', badgeLightClass]">
+            {{ pLabel }}
           </span>
         </div>
         <p v-if="plan.group_name" class="mt-1 text-xs text-gray-400 dark:text-dark-500">
@@ -31,14 +31,14 @@
       <div class="mb-4">
         <div class="flex items-baseline gap-1.5">
           <span class="text-sm text-gray-400 dark:text-dark-500">&yen;</span>
-          <span :class="['text-4xl font-extrabold tracking-tight', priceClass]">{{ plan.price }}</span>
+          <span :class="['text-4xl font-extrabold tracking-tight', textClass]">{{ plan.price }}</span>
           <span class="text-sm text-gray-400 dark:text-dark-500">/ {{ validitySuffix }}</span>
         </div>
         <div v-if="plan.original_price" class="mt-1 flex items-center gap-2">
           <span class="text-sm text-gray-400 line-through dark:text-dark-500">
             &yen;{{ plan.original_price }}
           </span>
-          <span :class="['rounded px-1.5 py-0.5 text-[11px] font-semibold', discountBadgeClass]">
+          <span :class="['rounded px-1.5 py-0.5 text-[11px] font-semibold', discountClass]">
             {{ discountText }}
           </span>
         </div>
@@ -46,32 +46,26 @@
 
       <!-- Group quota info -->
       <div class="mb-4 space-y-1.5 rounded-lg bg-gray-50 px-3 py-2.5 dark:bg-dark-700/50">
-        <!-- Rate multiplier -->
         <div class="flex items-center justify-between text-xs">
           <span class="text-gray-400 dark:text-dark-500">{{ t('payment.planCard.rate') }}</span>
           <span class="font-medium text-gray-700 dark:text-gray-300">{{ rateDisplay }}</span>
         </div>
-        <!-- Daily limit -->
         <div v-if="plan.daily_limit_usd != null" class="flex items-center justify-between text-xs">
           <span class="text-gray-400 dark:text-dark-500">{{ t('payment.planCard.dailyLimit') }}</span>
           <span class="font-medium text-gray-700 dark:text-gray-300">${{ plan.daily_limit_usd }}</span>
         </div>
-        <!-- Weekly limit -->
         <div v-if="plan.weekly_limit_usd != null" class="flex items-center justify-between text-xs">
           <span class="text-gray-400 dark:text-dark-500">{{ t('payment.planCard.weeklyLimit') }}</span>
           <span class="font-medium text-gray-700 dark:text-gray-300">${{ plan.weekly_limit_usd }}</span>
         </div>
-        <!-- Monthly limit -->
         <div v-if="plan.monthly_limit_usd != null" class="flex items-center justify-between text-xs">
           <span class="text-gray-400 dark:text-dark-500">{{ t('payment.planCard.monthlyLimit') }}</span>
           <span class="font-medium text-gray-700 dark:text-gray-300">${{ plan.monthly_limit_usd }}</span>
         </div>
-        <!-- No limits indicator -->
         <div v-if="plan.daily_limit_usd == null && plan.weekly_limit_usd == null && plan.monthly_limit_usd == null" class="flex items-center justify-between text-xs">
           <span class="text-gray-400 dark:text-dark-500">{{ t('payment.planCard.quota') }}</span>
           <span class="font-medium text-gray-700 dark:text-gray-300">{{ t('payment.planCard.unlimited') }}</span>
         </div>
-        <!-- Model scopes -->
         <div v-if="modelScopeLabels.length > 0" class="flex items-center justify-between text-xs">
           <span class="text-gray-400 dark:text-dark-500">{{ t('payment.planCard.models') }}</span>
           <div class="flex flex-wrap justify-end gap-1">
@@ -85,24 +79,19 @@
 
       <!-- Features list with checkmarks -->
       <div v-if="plan.features.length > 0" class="mb-4 space-y-2">
-        <div
-          v-for="feature in plan.features"
-          :key="feature"
-          class="flex items-start gap-2"
-        >
-          <svg :class="['mt-0.5 h-4 w-4 flex-shrink-0', checkIconClass]" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2">
+        <div v-for="feature in plan.features" :key="feature" class="flex items-start gap-2">
+          <svg :class="['mt-0.5 h-4 w-4 flex-shrink-0', iconClass]" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2">
             <path stroke-linecap="round" stroke-linejoin="round" d="M4.5 12.75l6 6 9-13.5" />
           </svg>
           <span class="text-sm text-gray-600 dark:text-gray-300">{{ feature }}</span>
         </div>
       </div>
 
-      <!-- Spacer pushes button to bottom -->
       <div class="flex-1" />
 
       <!-- Validity badge -->
       <div class="mb-3 text-center">
-        <span :class="['rounded-full px-3 py-1 text-xs font-medium', badgeClass]">
+        <span :class="['rounded-full px-3 py-1 text-xs font-medium', badgeLightClass]">
           {{ validityLabel }}
         </span>
       </div>
@@ -110,11 +99,7 @@
       <!-- Subscribe Button -->
       <button
         type="button"
-        :class="[
-          'w-full rounded-xl py-2.5 text-sm font-semibold transition-all',
-          'active:scale-[0.98]',
-          buttonClass,
-        ]"
+        :class="['w-full rounded-xl py-2.5 text-sm font-semibold transition-all active:scale-[0.98]', btnClass]"
         @click="emit('select', plan)"
       >
         {{ t('payment.subscribeNow') }}
@@ -127,44 +112,44 @@
 import { computed } from 'vue'
 import { useI18n } from 'vue-i18n'
 import type { SubscriptionPlan } from '@/types/payment'
+import {
+  platformAccentBarClass,
+  platformBadgeLightClass,
+  platformBorderClass,
+  platformTextClass,
+  platformIconClass,
+  platformButtonClass,
+  platformDiscountClass,
+  platformLabel,
+} from '@/utils/platformColors'
 
-const props = defineProps<{
-  plan: SubscriptionPlan
-}>()
-
-const emit = defineEmits<{
-  select: [plan: SubscriptionPlan]
-}>()
-
+const props = defineProps<{ plan: SubscriptionPlan }>()
+const emit = defineEmits<{ select: [plan: SubscriptionPlan] }>()
 const { t } = useI18n()
 
 const platform = computed(() => props.plan.group_platform || '')
 
-// Discount percentage
+// Derived color classes from central config
+const accentClass = computed(() => platformAccentBarClass(platform.value))
+const borderClass = computed(() => platformBorderClass(platform.value))
+const badgeLightClass = computed(() => platformBadgeLightClass(platform.value))
+const textClass = computed(() => platformTextClass(platform.value))
+const iconClass = computed(() => platformIconClass(platform.value))
+const btnClass = computed(() => platformButtonClass(platform.value))
+const discountClass = computed(() => platformDiscountClass(platform.value))
+const pLabel = computed(() => platformLabel(platform.value))
+
 const discountText = computed(() => {
   if (!props.plan.original_price || props.plan.original_price <= 0) return ''
   const pct = Math.round((1 - props.plan.price / props.plan.original_price) * 100)
   return pct > 0 ? `-${pct}%` : ''
 })
 
-// Rate multiplier display
 const rateDisplay = computed(() => {
   const rate = props.plan.rate_multiplier ?? 1
   return `×${Number(rate.toPrecision(10))}`
 })
 
-// Platform display label
-const platformLabel = computed(() => {
-  switch (platform.value) {
-    case 'anthropic': return 'Anthropic'
-    case 'openai': return 'OpenAI'
-    case 'antigravity': return 'Antigravity'
-    case 'gemini': return 'Gemini'
-    default: return platform.value || 'API'
-  }
-})
-
-// Model scope labels
 const MODEL_SCOPE_LABELS: Record<string, string> = {
   claude: 'Claude',
   gemini_text: 'Gemini',
@@ -177,87 +162,6 @@ const modelScopeLabels = computed(() => {
   return scopes.map(s => MODEL_SCOPE_LABELS[s] || s)
 })
 
-// Color schemes per platform
-const accentBarClass = computed(() => {
-  switch (platform.value) {
-    case 'anthropic': return 'bg-gradient-to-r from-orange-400 to-orange-500'
-    case 'openai': return 'bg-gradient-to-r from-emerald-400 to-emerald-500'
-    case 'antigravity': return 'bg-gradient-to-r from-purple-400 to-purple-500'
-    case 'gemini': return 'bg-gradient-to-r from-blue-400 to-blue-500'
-    default: return 'bg-gradient-to-r from-primary-400 to-primary-500'
-  }
-})
-
-const cardBorderClass = computed(() => {
-  switch (platform.value) {
-    case 'anthropic': return 'border-orange-100 dark:border-orange-900/30'
-    case 'openai': return 'border-emerald-100 dark:border-emerald-900/30'
-    case 'antigravity': return 'border-purple-100 dark:border-purple-900/30'
-    case 'gemini': return 'border-blue-100 dark:border-blue-900/30'
-    default: return 'border-gray-200 dark:border-dark-700'
-  }
-})
-
-const platformBadgeClass = computed(() => {
-  switch (platform.value) {
-    case 'anthropic': return 'bg-orange-50 text-orange-600 dark:bg-orange-900/30 dark:text-orange-300'
-    case 'openai': return 'bg-emerald-50 text-emerald-600 dark:bg-emerald-900/30 dark:text-emerald-300'
-    case 'antigravity': return 'bg-purple-50 text-purple-600 dark:bg-purple-900/30 dark:text-purple-300'
-    case 'gemini': return 'bg-blue-50 text-blue-600 dark:bg-blue-900/30 dark:text-blue-300'
-    default: return 'bg-gray-100 text-gray-600 dark:bg-dark-700 dark:text-gray-300'
-  }
-})
-
-const badgeClass = computed(() => {
-  switch (platform.value) {
-    case 'anthropic': return 'bg-orange-50 text-orange-600 dark:bg-orange-900/30 dark:text-orange-300'
-    case 'openai': return 'bg-emerald-50 text-emerald-600 dark:bg-emerald-900/30 dark:text-emerald-300'
-    case 'antigravity': return 'bg-purple-50 text-purple-600 dark:bg-purple-900/30 dark:text-purple-300'
-    case 'gemini': return 'bg-blue-50 text-blue-600 dark:bg-blue-900/30 dark:text-blue-300'
-    default: return 'bg-gray-100 text-gray-600 dark:bg-dark-700 dark:text-gray-300'
-  }
-})
-
-const priceClass = computed(() => {
-  switch (platform.value) {
-    case 'anthropic': return 'text-orange-600 dark:text-orange-400'
-    case 'openai': return 'text-emerald-600 dark:text-emerald-400'
-    case 'antigravity': return 'text-purple-600 dark:text-purple-400'
-    case 'gemini': return 'text-blue-600 dark:text-blue-400'
-    default: return 'text-primary-600 dark:text-primary-400'
-  }
-})
-
-const discountBadgeClass = computed(() => {
-  switch (platform.value) {
-    case 'anthropic': return 'bg-orange-100 text-orange-700 dark:bg-orange-900/40 dark:text-orange-300'
-    case 'openai': return 'bg-emerald-100 text-emerald-700 dark:bg-emerald-900/40 dark:text-emerald-300'
-    case 'antigravity': return 'bg-purple-100 text-purple-700 dark:bg-purple-900/40 dark:text-purple-300'
-    case 'gemini': return 'bg-blue-100 text-blue-700 dark:bg-blue-900/40 dark:text-blue-300'
-    default: return 'bg-red-100 text-red-700 dark:bg-red-900/40 dark:text-red-300'
-  }
-})
-
-const checkIconClass = computed(() => {
-  switch (platform.value) {
-    case 'anthropic': return 'text-orange-500 dark:text-orange-400'
-    case 'openai': return 'text-emerald-500 dark:text-emerald-400'
-    case 'antigravity': return 'text-purple-500 dark:text-purple-400'
-    case 'gemini': return 'text-blue-500 dark:text-blue-400'
-    default: return 'text-primary-500 dark:text-primary-400'
-  }
-})
-
-const buttonClass = computed(() => {
-  switch (platform.value) {
-    case 'anthropic': return 'bg-orange-500 text-white hover:bg-orange-600 dark:bg-orange-600 dark:hover:bg-orange-500'
-    case 'openai': return 'bg-emerald-500 text-white hover:bg-emerald-600 dark:bg-emerald-600 dark:hover:bg-emerald-500'
-    case 'antigravity': return 'bg-purple-500 text-white hover:bg-purple-600 dark:bg-purple-600 dark:hover:bg-purple-500'
-    case 'gemini': return 'bg-blue-500 text-white hover:bg-blue-600 dark:bg-blue-600 dark:hover:bg-blue-500'
-    default: return 'bg-primary-500 text-white hover:bg-primary-600 dark:bg-primary-600 dark:hover:bg-primary-500'
-  }
-})
-
 const validityLabel = computed(() => {
   const d = props.plan.validity_days
   const u = props.plan.validity_unit || 'day'
diff --git a/frontend/src/utils/platformColors.ts b/frontend/src/utils/platformColors.ts
new file mode 100644
index 0000000000..79c6482bd2
--- /dev/null
+++ b/frontend/src/utils/platformColors.ts
@@ -0,0 +1,127 @@
+/**
+ * Centralized platform color definitions.
+ *
+ * All components that need platform-specific styling should import from here
+ * instead of defining their own color mappings.
+ */
+
+export type Platform = 'anthropic' | 'openai' | 'antigravity' | 'gemini'
+
+// ── Badge (bg + text) ───────────────────────────────────────────────
+const BADGE: Record<Platform, string> = {
+  anthropic: 'bg-orange-100 text-orange-700 dark:bg-orange-900/30 dark:text-orange-400',
+  openai: 'bg-emerald-100 text-emerald-700 dark:bg-emerald-900/30 dark:text-emerald-400',
+  antigravity: 'bg-purple-100 text-purple-700 dark:bg-purple-900/30 dark:text-purple-400',
+  gemini: 'bg-blue-100 text-blue-700 dark:bg-blue-900/30 dark:text-blue-400',
+}
+const BADGE_DEFAULT = 'bg-gray-100 text-gray-600 dark:bg-dark-700 dark:text-gray-300'
+
+// ── Light badge (softer bg) ─────────────────────────────────────────
+const BADGE_LIGHT: Record<Platform, string> = {
+  anthropic: 'bg-orange-50 text-orange-600 dark:bg-orange-900/30 dark:text-orange-300',
+  openai: 'bg-emerald-50 text-emerald-600 dark:bg-emerald-900/30 dark:text-emerald-300',
+  antigravity: 'bg-purple-50 text-purple-600 dark:bg-purple-900/30 dark:text-purple-300',
+  gemini: 'bg-blue-50 text-blue-600 dark:bg-blue-900/30 dark:text-blue-300',
+}
+
+// ── Border ──────────────────────────────────────────────────────────
+const BORDER: Record<Platform, string> = {
+  anthropic: 'border-orange-100 dark:border-orange-900/30',
+  openai: 'border-emerald-100 dark:border-emerald-900/30',
+  antigravity: 'border-purple-100 dark:border-purple-900/30',
+  gemini: 'border-blue-100 dark:border-blue-900/30',
+}
+const BORDER_DEFAULT = 'border-gray-200 dark:border-dark-700'
+
+// ── Accent bar (gradient) ───────────────────────────────────────────
+const ACCENT_BAR: Record<Platform, string> = {
+  anthropic: 'bg-gradient-to-r from-orange-400 to-orange-500',
+  openai: 'bg-gradient-to-r from-emerald-400 to-emerald-500',
+  antigravity: 'bg-gradient-to-r from-purple-400 to-purple-500',
+  gemini: 'bg-gradient-to-r from-blue-400 to-blue-500',
+}
+const ACCENT_BAR_DEFAULT = 'bg-gradient-to-r from-primary-400 to-primary-500'
+
+// ── Text (price, icon) ─────────────────────────────────────────────
+const TEXT: Record<Platform, string> = {
+  anthropic: 'text-orange-600 dark:text-orange-400',
+  openai: 'text-emerald-600 dark:text-emerald-400',
+  antigravity: 'text-purple-600 dark:text-purple-400',
+  gemini: 'text-blue-600 dark:text-blue-400',
+}
+const TEXT_DEFAULT = 'text-primary-600 dark:text-primary-400'
+
+// ── Icon (check mark etc.) ──────────────────────────────────────────
+const ICON: Record<Platform, string> = {
+  anthropic: 'text-orange-500 dark:text-orange-400',
+  openai: 'text-emerald-500 dark:text-emerald-400',
+  antigravity: 'text-purple-500 dark:text-purple-400',
+  gemini: 'text-blue-500 dark:text-blue-400',
+}
+const ICON_DEFAULT = 'text-primary-500 dark:text-primary-400'
+
+// ── Button (solid bg) ───────────────────────────────────────────────
+const BUTTON: Record<Platform, string> = {
+  anthropic: 'bg-orange-500 text-white hover:bg-orange-600 dark:bg-orange-600 dark:hover:bg-orange-500',
+  openai: 'bg-emerald-500 text-white hover:bg-emerald-600 dark:bg-emerald-600 dark:hover:bg-emerald-500',
+  antigravity: 'bg-purple-500 text-white hover:bg-purple-600 dark:bg-purple-600 dark:hover:bg-purple-500',
+  gemini: 'bg-blue-500 text-white hover:bg-blue-600 dark:bg-blue-600 dark:hover:bg-blue-500',
+}
+const BUTTON_DEFAULT = 'bg-primary-500 text-white hover:bg-primary-600 dark:bg-primary-600 dark:hover:bg-primary-500'
+
+// ── Discount badge ──────────────────────────────────────────────────
+const DISCOUNT: Record<Platform, string> = {
+  anthropic: 'bg-orange-100 text-orange-700 dark:bg-orange-900/40 dark:text-orange-300',
+  openai: 'bg-emerald-100 text-emerald-700 dark:bg-emerald-900/40 dark:text-emerald-300',
+  antigravity: 'bg-purple-100 text-purple-700 dark:bg-purple-900/40 dark:text-purple-300',
+  gemini: 'bg-blue-100 text-blue-700 dark:bg-blue-900/40 dark:text-blue-300',
+}
+const DISCOUNT_DEFAULT = 'bg-red-100 text-red-700 dark:bg-red-900/40 dark:text-red-300'
+
+// ── Public API ──────────────────────────────────────────────────────
+
+function isPlatform(p: string): p is Platform {
+  return p === 'anthropic' || p === 'openai' || p === 'antigravity' || p === 'gemini'
+}
+
+export function platformBadgeClass(p: string): string {
+  return isPlatform(p) ? BADGE[p] : BADGE_DEFAULT
+}
+
+export function platformBadgeLightClass(p: string): string {
+  return isPlatform(p) ? BADGE_LIGHT[p] : BADGE_DEFAULT
+}
+
+export function platformBorderClass(p: string): string {
+  return isPlatform(p) ? BORDER[p] : BORDER_DEFAULT
+}
+
+export function platformAccentBarClass(p: string): string {
+  return isPlatform(p) ? ACCENT_BAR[p] : ACCENT_BAR_DEFAULT
+}
+
+export function platformTextClass(p: string): string {
+  return isPlatform(p) ? TEXT[p] : TEXT_DEFAULT
+}
+
+export function platformIconClass(p: string): string {
+  return isPlatform(p) ? ICON[p] : ICON_DEFAULT
+}
+
+export function platformButtonClass(p: string): string {
+  return isPlatform(p) ? BUTTON[p] : BUTTON_DEFAULT
+}
+
+export function platformDiscountClass(p: string): string {
+  return isPlatform(p) ? DISCOUNT[p] : DISCOUNT_DEFAULT
+}
+
+export function platformLabel(p: string): string {
+  switch (p) {
+    case 'anthropic': return 'Anthropic'
+    case 'openai': return 'OpenAI'
+    case 'antigravity': return 'Antigravity'
+    case 'gemini': return 'Gemini'
+    default: return p || 'API'
+  }
+}