feat(channels): explode available channels by platform + apply platform theme

Backend: one source channel → N output rows, one per platform that
has user-visible groups. Each row carries a single platform, so the
frontend can color/icon an entire row without mixing sources.

- userAvailableChannel: add Platform field
- new explodeChannelByPlatform helper; drop now-redundant
  collectGroupPlatforms

Frontend: use the row platform to drive theming and stop repeating
"ANTHROPIC" / "OPENAI" labels on every model chip.

- api/channels.ts: UserAvailableChannel.platform
- AvailableChannelsTable: name cell — PlatformBadge next to channel
  name (replaces the two-line name/description block; description
  moves to the badge's title tooltip); groups cell — each chip uses
  platformBadgeLightClass + PlatformIcon; model list passes
  show-platform=false + platform-hint to child chips
- SupportedModelChip: chip bg/border driven by platformBadgeClass,
  leading PlatformIcon; platform-hint fallback when model.platform
  missing

backend/internal/handler/available_channel_handler.go

 package handler
 
 import (
+	"sort"
+
 	"github.com/Wei-Shaw/sub2api/internal/pkg/response"
 	"github.com/Wei-Shaw/sub2api/internal/server/middleware"
 	"github.com/Wei-Shaw/sub2api/internal/service"
@@ -84,9 +86,14 @@ type userSupportedModel struct {
 }
 
 // userAvailableChannel 用户可见的渠道条目（白名单字段）。
+//
+// 同一个渠道若在多个平台上都有用户可见的分组，会被摊开成多条记录 —— 每条对应
+// 一个平台，groups 和 supported_models 都只包含该平台的内容。这样前端无需在
+// 一行内混排多平台信息，也能直接为整行应用平台色/图标。
 type userAvailableChannel struct {
 	Name            string               `json:"name"`
 	Description     string               `json:"description"`
+	Platform        string               `json:"platform"`
 	Groups          []userAvailableGroup `json:"groups"`
 	SupportedModels []userSupportedModel `json:"supported_models"`
 }
@@ -132,28 +139,48 @@ func (h *AvailableChannelHandler) List(c *gin.Context) {
 		if len(visibleGroups) == 0 {
 			continue
 		}
-		allowedPlatforms := collectGroupPlatforms(visibleGroups)
-		out = append(out, userAvailableChannel{
-			Name:            ch.Name,
-			Description:     ch.Description,
-			Groups:          visibleGroups,
-			SupportedModels: toUserSupportedModels(ch.SupportedModels, allowedPlatforms),
-		})
+		out = append(out, explodeChannelByPlatform(ch, visibleGroups)...)
 	}
 
 	response.Success(c, out)
 }
 
-// collectGroupPlatforms 聚合 visible groups 覆盖的平台集合，用于过滤 SupportedModels。
-func collectGroupPlatforms(groups []userAvailableGroup) map[string]struct{} {
-	set := make(map[string]struct{}, len(groups))
-	for _, g := range groups {
+// explodeChannelByPlatform 将单个渠道按 visibleGroups 的平台集合摊开成多条记录。
+// 每条记录对应一个平台：groups 仅含该平台的 visibleGroups，supported_models 仅含
+// 该平台的模型。输出按 platform 字母序稳定排序，便于前端等效比较与回归测试。
+func explodeChannelByPlatform(
+	ch service.AvailableChannel,
+	visibleGroups []userAvailableGroup,
+) []userAvailableChannel {
+	groupsByPlatform := make(map[string][]userAvailableGroup, 4)
+	for _, g := range visibleGroups {
 		if g.Platform == "" {
 			continue
 		}
-		set[g.Platform] = struct{}{}
+		groupsByPlatform[g.Platform] = append(groupsByPlatform[g.Platform], g)
+	}
+	if len(groupsByPlatform) == 0 {
+		return nil
 	}
-	return set
+
+	platforms := make([]string, 0, len(groupsByPlatform))
+	for p := range groupsByPlatform {
+		platforms = append(platforms, p)
+	}
+	sort.Strings(platforms)
+
+	out := make([]userAvailableChannel, 0, len(platforms))
+	for _, platform := range platforms {
+		platformSet := map[string]struct{}{platform: {}}
+		out = append(out, userAvailableChannel{
+			Name:            ch.Name,
+			Description:     ch.Description,
+			Platform:        platform,
+			Groups:          groupsByPlatform[platform],
+			SupportedModels: toUserSupportedModels(ch.SupportedModels, platformSet),
+		})
+	}
+	return out
 }
 
 // filterUserVisibleGroups 仅保留用户可访问的分组。

backend/internal/handler/available_channel_handler_test.go

@@ -42,21 +42,6 @@ func TestFilterUserVisibleGroups_IntersectionOnly(t *testing.T) {
 	require.ElementsMatch(t, []int64{1, 3}, ids)
 }
 
-func TestCollectGroupPlatforms_DerivesAllowedSet(t *testing.T) {
-	groups := []userAvailableGroup{
-		{ID: 1, Platform: "anthropic"},
-		{ID: 2, Platform: "openai"},
-		{ID: 3, Platform: "anthropic"}, // 去重
-		{ID: 4, Platform: ""},          // 空平台忽略
-	}
-	got := collectGroupPlatforms(groups)
-	require.Len(t, got, 2)
-	_, hasAnt := got["anthropic"]
-	_, hasOA := got["openai"]
-	require.True(t, hasAnt)
-	require.True(t, hasOA)
-}
-
 func TestToUserSupportedModels_FiltersByAllowedPlatforms(t *testing.T) {
 	// 用户可访问分组只覆盖 anthropic；anthropic 平台的模型保留，openai 模型被剔除。
 	src := []service.SupportedModel{

frontend/src/api/channels.ts

@@ -43,6 +43,11 @@ export interface UserSupportedModel {
 export interface UserAvailableChannel {
   name: string
   description: string
+  /**
+   * 所属平台（anthropic / openai / antigravity / gemini ...）。后端按平台把一个渠道
+   * 摊开成多条记录，因此此字段决定整行的配色与图标。
+   */
+  platform: string
   groups: UserAvailableGroup[]
   supported_models: UserSupportedModel[]
 }

frontend/src/components/channels/AvailableChannelsTable.vue

 <template>
   <DataTable :columns="columns" :data="rows" :loading="loading">
     <template #cell-name="{ row }">
-      <div class="font-medium text-gray-900 dark:text-white">{{ row.name }}</div>
-      <div
-        v-if="row.description"
-        class="mt-0.5 text-xs text-gray-500 dark:text-gray-400"
-      >
-        {{ row.description }}
+      <div class="flex items-center gap-2">
+        <span class="font-medium text-gray-900 dark:text-white">{{ row.name }}</span>
+        <span
+          v-if="row.platform"
+          :class="[
+            'inline-flex items-center gap-1 rounded-md border px-1.5 py-0.5 text-[11px] font-medium uppercase',
+            platformBadgeClass(row.platform),
+          ]"
+          :title="row.description || undefined"
+        >
+          <PlatformIcon :platform="row.platform as GroupPlatform" size="xs" />
+          {{ row.platform }}
+        </span>
       </div>
     </template>
 
@@ -18,8 +25,16 @@
         <span
           v-for="g in row.groups"
           :key="g.id"
-          class="inline-flex items-center rounded bg-blue-50 px-2 py-0.5 text-xs font-medium text-blue-700 dark:bg-blue-900/30 dark:text-blue-300"
+          :class="[
+            'inline-flex items-center gap-1 rounded px-2 py-0.5 text-xs font-medium',
+            platformBadgeLightClass(g.platform || row.platform || ''),
+          ]"
         >
+          <PlatformIcon
+            v-if="g.platform || row.platform"
+            :platform="(g.platform || row.platform) as GroupPlatform"
+            size="xs"
+          />
           {{ g.name }}
         </span>
       </div>
@@ -36,6 +51,8 @@
           :model="m"
           :pricing-key-prefix="pricingKeyPrefix"
           :no-pricing-label="noPricingLabel"
+          :show-platform="false"
+          :platform-hint="row.platform"
         />
       </div>
     </template>
@@ -60,9 +77,12 @@
 import { computed, useSlots } from 'vue'
 import DataTable from '@/components/common/DataTable.vue'
 import Icon from '@/components/icons/Icon.vue'
+import PlatformIcon from '@/components/common/PlatformIcon.vue'
 import SupportedModelChip from './SupportedModelChip.vue'
 import type { UserSupportedModel } from '@/api/channels'
 import type { ChannelStatus, BillingModelSource } from '@/constants/channel'
+import type { GroupPlatform } from '@/types'
+import { platformBadgeClass, platformBadgeLightClass } from '@/utils/platformColors'
 
 interface GroupRef {
   id: number
@@ -73,6 +93,8 @@ interface GroupRef {
 interface Row {
   name: string
   description?: string
+  /** 单条记录归属的平台；后端按平台摊开后每行一个。admin 场景可能缺失，因此允许 optional。 */
+  platform?: string
   groups: GroupRef[]
   // 复用 user 侧最小 DTO；admin 侧 SupportedModel 结构上是其超集，可直接传入。
   supported_models: UserSupportedModel[]

frontend/src/components/channels/SupportedModelChip.vue

 <template>
   <div class="group relative inline-block">
     <span
-      class="inline-flex cursor-help items-center rounded-md border border-gray-200 bg-gray-50 px-2 py-0.5 text-xs font-medium text-gray-700 transition-colors hover:border-brand-400 hover:bg-brand-50 hover:text-brand-700 dark:border-dark-600 dark:bg-dark-800 dark:text-gray-300 dark:hover:border-brand-500 dark:hover:bg-brand-900/30 dark:hover:text-brand-300"
+      :class="[
+        'inline-flex cursor-help items-center gap-1 rounded-md border px-2 py-0.5 text-xs font-medium transition-colors',
+        effectivePlatform
+          ? platformBadgeClass(effectivePlatform)
+          : 'border-gray-200 bg-gray-50 text-gray-700 dark:border-dark-600 dark:bg-dark-800 dark:text-gray-300',
+      ]"
     >
+      <PlatformIcon
+        v-if="effectivePlatform"
+        :platform="effectivePlatform as GroupPlatform"
+        size="xs"
+      />
       <span
         v-if="showPlatform && model.platform"
-        class="mr-1 rounded bg-gray-200 px-1 text-[10px] uppercase text-gray-600 dark:bg-dark-700 dark:text-gray-400"
+        class="rounded bg-gray-200/60 px-1 text-[10px] uppercase text-gray-600 dark:bg-dark-700 dark:text-gray-400"
       >
         {{ model.platform }}
       </span>
@@ -130,6 +140,9 @@ import {
 // 复用 api/channels.ts 的用户侧最小形态 DTO。
 // admin 侧 ChannelModelPricing 字段更多，但结构上是用户 DTO 的超集，admin 视图传入可直接通过结构化子类型检查。
 import type { UserPricingInterval, UserSupportedModel } from '@/api/channels'
+import PlatformIcon from '@/components/common/PlatformIcon.vue'
+import type { GroupPlatform } from '@/types'
+import { platformBadgeClass } from '@/utils/platformColors'
 
 const props = withDefaults(
   defineProps<{
@@ -138,14 +151,22 @@ const props = withDefaults(
     pricingKeyPrefix?: string
     noPricingLabel?: string
     showPlatform?: boolean
+    /**
+     * 当 model.platform 缺失（如 admin 聚合场景）时，用父行的平台作为兜底着色。
+     * 仅用于视觉，不影响业务逻辑。
+     */
+    platformHint?: string
   }>(),
   {
     pricingKeyPrefix: 'availableChannels.pricing',
     noPricingLabel: '',
-    showPlatform: true
+    showPlatform: true,
+    platformHint: ''
   }
 )
 
+const effectivePlatform = computed<string>(() => props.model.platform || props.platformHint || '')
+
 const { t } = useI18n()
 
 /** 按 token 定价展示时的换算单位：每百万 token。 */