feat(conversation): OpenAI gpt-realtime-2.1 라이브 음성 대화 Premium 백엔드

- realtime-token Edge Function: 티어 검증 + realtime_session 쿼터 + ephemeral key 발급
- useRealtimeConversation 훅: WebRTC 직결 (마이크 → OpenAI, 오디오 자동 재생)
- VoiceConversationPage: conversationBackend 분기 + 연결 실패 시 로컬 fallback
- AppConfig.conversationBackend + SettingsModal 음성 대화 엔진 선택
- ErrorCode 799 ConversationRealtimeTokenFailed, i18n ko/en

server/supabase/functions/_shared/quota.ts

@@ -13,6 +13,7 @@ export type QuotaFeature =
   | 'llm_haiku'
   | 'llm_sonnet'
   | 'llm_opus'
+  | 'realtime_session'
 
 export type QuotaPeriod = 'daily' | 'weekly'
 
@@ -29,18 +30,22 @@ const MODEL_QUOTA: Record<Tier, Record<QuotaFeature, ModelQuota>> = {
     llm_haiku: { limit: 250, period: 'weekly' },
     llm_sonnet: { limit: 0, period: 'daily' },   // 사용불가
     llm_opus: { limit: 0, period: 'daily' },      // 사용불가
+    realtime_session: { limit: 0, period: 'daily' }, // 사용불가
   },
   pro: {
     stt_transcribe: { limit: -1, period: 'daily' },
     llm_haiku: { limit: 1500, period: 'daily' },
     llm_sonnet: { limit: 300, period: 'daily' },
     llm_opus: { limit: 50, period: 'daily' },
+    // 세션 수 기준 (~$0.016/분 mini — 세션당 평균 수 분 가정)
+    realtime_session: { limit: 30, period: 'daily' },
   },
   pro_plus: {
     stt_transcribe: { limit: -1, period: 'daily' },
     llm_haiku: { limit: -1, period: 'daily' },    // 무제한
     llm_sonnet: { limit: 1500, period: 'daily' },
     llm_opus: { limit: 300, period: 'daily' },
+    realtime_session: { limit: 120, period: 'daily' },
   },
 }
 

server/supabase/functions/realtime-token/index.ts

@@ -0,0 +1,173 @@
+// server/supabase/functions/realtime-token/index.ts
+// OpenAI Realtime API ephemeral token 발급.
+// 렌더러가 이 토큰으로 OpenAI와 직접 WebRTC 연결한다 (서버 키 비노출).
+// 요청: application/json { model?, voice?, instructions? }
+// 응답: OpenAI client_secrets 응답 그대로 + { model, tier }
+
+import { corsHeaders, handleCorsPreflightRequest } from '../_shared/cors.ts'
+import { requireUser, authErrorResponse, type AuthError } from '../_shared/auth.ts'
+import {
+  checkQuota,
+  consumeQuota,
+  createServiceRoleClient,
+  getQuotaPolicy,
+  type Tier,
+} from '../_shared/quota.ts'
+
+interface RealtimeTokenRequest {
+  model?: string
+  voice?: string
+  instructions?: string
+}
+
+/** 티어별 허용 Realtime 모델 — free 차단, pro는 mini만, pro_plus는 풀 모델까지 */
+const TIER_MODELS: Record<Tier, string[]> = {
+  free: [],
+  pro: ['gpt-realtime-2.1-mini'],
+  pro_plus: ['gpt-realtime-2.1', 'gpt-realtime-2.1-mini'],
+}
+
+const DEFAULT_MODEL: Record<Tier, string | null> = {
+  free: null,
+  pro: 'gpt-realtime-2.1-mini',
+  pro_plus: 'gpt-realtime-2.1',
+}
+
+const DEFAULT_VOICE = 'marin'
+const MAX_INSTRUCTIONS_LENGTH = 2000
+
+// @ts-expect-error — Deno 런타임 전역
+Deno.serve(async (req: Request) => {
+  const preflight = handleCorsPreflightRequest(req)
+  if (preflight) return preflight
+
+  if (req.method !== 'POST') {
+    return new Response(JSON.stringify({ error: 'Method not allowed' }), {
+      status: 405,
+      headers: { ...corsHeaders, 'Content-Type': 'application/json' },
+    })
+  }
+
+  try {
+    const user = await requireUser(req)
+    const serviceClient = createServiceRoleClient()
+
+    const body = (await req.json().catch(() => ({}))) as RealtimeTokenRequest
+
+    // 1단계: 티어 + 세션 쿼터 확인
+    const quota = await checkQuota(user.id, 'realtime_session', serviceClient)
+    const tier = quota.tier
+
+    const requestedModel = body.model ?? DEFAULT_MODEL[tier]
+    if (!requestedModel || !TIER_MODELS[tier].includes(requestedModel)) {
+      return new Response(
+        JSON.stringify({
+          error: tier === 'free' ? 'tier_not_allowed' : 'model_not_allowed',
+          tier,
+          requested: body.model ?? null,
+          allowed: TIER_MODELS[tier],
+        }),
+        {
+          status: 403,
+          headers: { ...corsHeaders, 'Content-Type': 'application/json' },
+        },
+      )
+    }
+
+    if (!quota.allowed) {
+      return new Response(
+        JSON.stringify({
+          error: 'quota_exceeded',
+          current: quota.current,
+          limit: quota.limit,
+          period: quota.period,
+          tier,
+          overage_credits: quota.overageCredits,
+        }),
+        {
+          status: 429,
+          headers: { ...corsHeaders, 'Content-Type': 'application/json' },
+        },
+      )
+    }
+
+    // 2단계: 쿼터 소비 (세션 시작 = 1회)
+    const policy = getQuotaPolicy(tier, 'realtime_session')
+    const consume = await consumeQuota(user.id, 'realtime_session', serviceClient, policy.limit)
+    if (!consume.allowed) {
+      return new Response(
+        JSON.stringify({
+          error: 'quota_exceeded',
+          current: consume.current,
+          limit: consume.limit,
+          tier,
+          overage_credits: consume.overageCredits,
+        }),
+        {
+          status: 429,
+          headers: { ...corsHeaders, 'Content-Type': 'application/json' },
+        },
+      )
+    }
+
+    // @ts-expect-error — Deno.env
+    const openaiKey = Deno.env.get('OPENAI_API_KEY') ?? ''
+    if (!openaiKey) {
+      return new Response(
+        JSON.stringify({ error: 'not_configured', message: 'OPENAI_API_KEY 미설정' }),
+        {
+          status: 503,
+          headers: { ...corsHeaders, 'Content-Type': 'application/json' },
+        },
+      )
+    }
+
+    // 3단계: OpenAI ephemeral client secret 발급
+    const instructions =
+      typeof body.instructions === 'string'
+        ? body.instructions.slice(0, MAX_INSTRUCTIONS_LENGTH)
+        : undefined
+
+    const openaiResp = await fetch('https://api.openai.com/v1/realtime/client_secrets', {
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+        Authorization: `Bearer ${openaiKey}`,
+        'OpenAI-Safety-Identifier': user.id,
+      },
+      body: JSON.stringify({
+        session: {
+          type: 'realtime',
+          model: requestedModel,
+          ...(instructions ? { instructions } : {}),
+          audio: {
+            output: { voice: body.voice ?? DEFAULT_VOICE },
+          },
+        },
+      }),
+    })
+
+    if (!openaiResp.ok) {
+      const errText = await openaiResp.text()
+      throw new Error(`OpenAI ${openaiResp.status}: ${errText.slice(0, 500)}`)
+    }
+
+    const data = await openaiResp.json()
+    return new Response(
+      JSON.stringify({ ...data, model: requestedModel, tier }),
+      {
+        status: 200,
+        headers: { ...corsHeaders, 'Content-Type': 'application/json' },
+      },
+    )
+  } catch (err) {
+    if (err && typeof err === 'object' && 'status' in err && 'message' in err) {
+      return authErrorResponse(err as AuthError, corsHeaders)
+    }
+    const message = err instanceof Error ? err.message : 'Unknown error'
+    return new Response(JSON.stringify({ error: message }), {
+      status: 500,
+      headers: { ...corsHeaders, 'Content-Type': 'application/json' },
+    })
+  }
+})