diff --git a/server/supabase/functions/_shared/quota-reservation.test.ts b/server/supabase/functions/_shared/quota-reservation.test.ts
new file mode 100644
index 0000000..5b9e666
--- /dev/null
+++ b/server/supabase/functions/_shared/quota-reservation.test.ts
@@ -0,0 +1,112 @@
+import type { createClient } from '@supabase/supabase-js'
+import {
+  finalizeLlmQuota,
+  parseQuotaFinalizeResponse,
+  parseQuotaReservationResponse,
+  reserveLlmQuota,
+} from './quota.ts'
+
+function assert(condition: boolean, message: string): asserts condition {
+  if (!condition) throw new Error(message)
+}
+
+function assertThrows(fn: () => unknown, message: string): void {
+  try {
+    fn()
+  } catch {
+    return
+  }
+  throw new Error(message)
+}
+
+type ServiceClient = ReturnType<typeof createClient>
+
+class FakeRpcClient {
+  calls: Array<{ name: string; args: Record<string, unknown> }> = []
+  constructor(private readonly result: unknown, private readonly error: unknown = null) {}
+  rpc(name: string, args: Record<string, unknown>): Promise<{ data: unknown; error: unknown }> {
+    this.calls.push({ name, args })
+    return Promise.resolve({ data: this.result, error: this.error })
+  }
+}
+
+const RESERVED = {
+  allowed: true,
+  reservation_id: '6f1d8a0e-0000-4000-8000-000000000001',
+  status: 'reserved',
+  current: 3,
+  limit: 50,
+  period: 'daily',
+  tier: 'pro',
+  overage_credits: 0,
+  consumed_from: 'base',
+}
+
+Deno.test('parseQuotaReservationResponse accepts reserve RPC payloads', () => {
+  const parsed = parseQuotaReservationResponse(RESERVED, 'LLM')
+  assert(parsed.allowed && parsed.reservationId === RESERVED.reservation_id, 'reservation id')
+  assert(parsed.period === 'daily' && parsed.tier === 'pro' && parsed.consumedFrom === 'base', 'fields')
+
+  const denied = parseQuotaReservationResponse(
+    { ...RESERVED, allowed: false, reservation_id: null, status: 'denied', consumed_from: 'none' },
+    'LLM',
+  )
+  assert(!denied.allowed && denied.reservationId === null && denied.status === 'denied', 'denied')
+})
+
+Deno.test('parseQuotaReservationResponse rejects malformed payloads', () => {
+  assertThrows(() => parseQuotaReservationResponse(null, 'LLM'), 'null')
+  assertThrows(() => parseQuotaReservationResponse([], 'LLM'), 'array')
+  assertThrows(() => parseQuotaReservationResponse({ ...RESERVED, status: 'held' }, 'LLM'), 'status')
+  assertThrows(() => parseQuotaReservationResponse({ ...RESERVED, tier: 'gold' }, 'LLM'), 'tier')
+  assertThrows(() => parseQuotaReservationResponse({ ...RESERVED, period: 'monthly' }, 'LLM'), 'period')
+  assertThrows(() => parseQuotaReservationResponse({ ...RESERVED, current: '3' }, 'LLM'), 'current')
+})
+
+Deno.test('parseQuotaFinalizeResponse accepts completed/released only', () => {
+  assert(parseQuotaFinalizeResponse({ status: 'completed' }, 'LLM') === 'completed', 'completed')
+  assert(parseQuotaFinalizeResponse({ status: 'released' }, 'LLM') === 'released', 'released')
+  assertThrows(() => parseQuotaFinalizeResponse({ status: 'reserved' }, 'LLM'), 'reserved')
+})
+
+Deno.test('reserveLlmQuota calls reserve_llm_quota with feature, limit and period', async () => {
+  const client = new FakeRpcClient(RESERVED)
+  const result = await reserveLlmQuota(
+    'user-1',
+    RESERVED.reservation_id,
+    'llm_opus',
+    50,
+    'daily',
+    client as unknown as ServiceClient,
+  )
+  assert(result.reservationId === RESERVED.reservation_id, 'result')
+  assert(client.calls.length === 1 && client.calls[0].name === 'reserve_llm_quota', 'rpc name')
+  const args = client.calls[0].args
+  assert(
+    args.p_user_id === 'user-1'
+      && args.p_reservation_id === RESERVED.reservation_id
+      && args.p_feature === 'llm_opus'
+      && args.p_base_limit === 50
+      && args.p_period === 'daily',
+    'rpc args',
+  )
+})
+
+Deno.test('reserveLlmQuota throws on RPC error', async () => {
+  const client = new FakeRpcClient(null, { message: 'boom' })
+  let threw = false
+  try {
+    await reserveLlmQuota('user-1', 'r', 'llm_haiku', 250, 'weekly', client as unknown as ServiceClient)
+  } catch {
+    threw = true
+  }
+  assert(threw, 'must throw')
+})
+
+Deno.test('finalizeLlmQuota calls finalize_llm_quota', async () => {
+  const client = new FakeRpcClient({ reservation_id: 'r', status: 'released' })
+  const status = await finalizeLlmQuota('r', false, client as unknown as ServiceClient)
+  assert(status === 'released', 'status')
+  const call = client.calls[0]
+  assert(call.name === 'finalize_llm_quota' && call.args.p_reservation_id === 'r' && call.args.p_succeeded === false, 'rpc')
+})
diff --git a/server/supabase/functions/_shared/quota.ts b/server/supabase/functions/_shared/quota.ts
index 54ed7db..53d2177 100644
--- a/server/supabase/functions/_shared/quota.ts
+++ b/server/supabase/functions/_shared/quota.ts
@@ -60,7 +60,8 @@ export interface QuotaConsumeResult {
   consumedFrom: QuotaConsumedFrom
 }
 
-export interface SttQuotaReservation {
+/** reserve_*_quota RPC 결과 — 공급자 호출 전에 한 단위를 잡아 두는 리스(lease). */
+export interface QuotaReservation {
   allowed: boolean
   reservationId: string | null
   status: 'reserved' | 'completed' | 'released' | 'denied'
@@ -72,6 +73,59 @@ export interface SttQuotaReservation {
   consumedFrom: 'base' | 'overage' | 'unlimited' | 'none'
 }
 
+export type SttQuotaReservation = QuotaReservation
+
+export type QuotaReservationFinalStatus = 'completed' | 'released'
+
+const RESERVATION_STATUSES: readonly unknown[] = ['reserved', 'completed', 'released', 'denied']
+const QUOTA_PERIODS: readonly unknown[] = ['daily', 'weekly']
+const QUOTA_TIERS: readonly unknown[] = ['free', 'pro', 'pro_plus', 'team', 'enterprise']
+const RESERVATION_SOURCES: readonly unknown[] = ['base', 'overage', 'unlimited', 'none']
+
+/** reserve_stt_quota / reserve_llm_quota 공통 응답 검증. 형식이 어긋나면 throw. */
+export function parseQuotaReservationResponse(data: unknown, label: string): QuotaReservation {
+  if (!data || typeof data !== 'object' || Array.isArray(data)) {
+    throw new Error(`Invalid ${label} quota reservation response.`)
+  }
+  const result = data as Record<string, unknown>
+  if (
+    typeof result.allowed !== 'boolean'
+    || (result.reservation_id !== null && typeof result.reservation_id !== 'string')
+    || !RESERVATION_STATUSES.includes(result.status)
+    || typeof result.current !== 'number'
+    || typeof result.limit !== 'number'
+    || !QUOTA_PERIODS.includes(result.period)
+    || !QUOTA_TIERS.includes(result.tier)
+    || typeof result.overage_credits !== 'number'
+    || !RESERVATION_SOURCES.includes(result.consumed_from)
+  ) {
+    throw new Error(`Invalid ${label} quota reservation response.`)
+  }
+  return {
+    allowed: result.allowed,
+    reservationId: result.reservation_id as string | null,
+    status: result.status as QuotaReservation['status'],
+    current: result.current,
+    limit: result.limit,
+    period: result.period as QuotaPeriod,
+    tier: result.tier as Tier,
+    overageCredits: result.overage_credits,
+    consumedFrom: result.consumed_from as QuotaReservation['consumedFrom'],
+  }
+}
+
+/** finalize_*_quota RPC 공통 응답 검증. */
+export function parseQuotaFinalizeResponse(data: unknown, label: string): QuotaReservationFinalStatus {
+  if (!data || typeof data !== 'object' || Array.isArray(data)) {
+    throw new Error(`Invalid ${label} quota finalization response.`)
+  }
+  const status = (data as Record<string, unknown>).status
+  if (status !== 'completed' && status !== 'released') {
+    throw new Error(`Invalid ${label} quota finalization response.`)
+  }
+  return status
+}
+
 export async function reserveSttQuota(
   userId: string,
   reservationId: string,
@@ -84,38 +138,14 @@ export async function reserveSttQuota(
   if (error || !data || typeof data !== 'object' || Array.isArray(data)) {
     throw new Error('Failed to reserve STT quota.')
   }
-  const result = data as Record<string, unknown>
-  if (
-    typeof result.allowed !== 'boolean'
-    || (result.reservation_id !== null && typeof result.reservation_id !== 'string')
-    || !['reserved', 'completed', 'released', 'denied'].includes(String(result.status))
-    || typeof result.current !== 'number'
-    || typeof result.limit !== 'number'
-    || !['daily', 'weekly'].includes(String(result.period))
-    || !['free', 'pro', 'pro_plus', 'team', 'enterprise'].includes(String(result.tier))
-    || typeof result.overage_credits !== 'number'
-    || !['base', 'overage', 'unlimited', 'none'].includes(String(result.consumed_from))
-  ) {
-    throw new Error('Invalid STT quota reservation response.')
-  }
-  return {
-    allowed: result.allowed,
-    reservationId: result.reservation_id as string | null,
-    status: result.status as SttQuotaReservation['status'],
-    current: result.current,
-    limit: result.limit,
-    period: result.period as QuotaPeriod,
-    tier: result.tier as Tier,
-    overageCredits: result.overage_credits,
-    consumedFrom: result.consumed_from as SttQuotaReservation['consumedFrom'],
-  }
+  return parseQuotaReservationResponse(data, 'STT')
 }
 
 export async function finalizeSttQuota(
   reservationId: string,
   succeeded: boolean,
   serviceRoleClient: ReturnType<typeof createClient>,
-): Promise<'completed' | 'released'> {
+): Promise<QuotaReservationFinalStatus> {
   const { data, error } = await serviceRoleClient.rpc('finalize_stt_quota', {
     p_reservation_id: reservationId,
     p_succeeded: succeeded,
@@ -123,11 +153,50 @@ export async function finalizeSttQuota(
   if (error || !data || typeof data !== 'object' || Array.isArray(data)) {
     throw new Error('Failed to finalize STT quota.')
   }
-  const status = (data as Record<string, unknown>).status
-  if (status !== 'completed' && status !== 'released') {
-    throw new Error('Invalid STT quota finalization response.')
+  return parseQuotaFinalizeResponse(data, 'STT')
+}
+
+/**
+ * LLM 쿼터 한 단위를 공급자 호출 **전에** 잡는다 (`reserve_llm_quota`).
+ * consume_quota 와 같은 per-user/feature advisory lock 아래에서 진행 중인 요청까지
+ * 사용량에 포함하므로, 동시 요청이 한도를 넘어 공급자 비용을 쓰지 못한다.
+ * 성공/실패는 finalizeLlmQuota 로 확정하고, 확정되지 않은 리스는 10분 뒤 환불된다.
+ */
+export async function reserveLlmQuota(
+  userId: string,
+  reservationId: string,
+  feature: QuotaFeature,
+  baseLimit: number,
+  period: QuotaPeriod,
+  serviceRoleClient: ReturnType<typeof createClient>,
+): Promise<QuotaReservation> {
+  const { data, error } = await serviceRoleClient.rpc('reserve_llm_quota', {
+    p_user_id: userId,
+    p_reservation_id: reservationId,
+    p_feature: feature,
+    p_base_limit: baseLimit,
+    p_period: period,
+  })
+  if (error || !data || typeof data !== 'object' || Array.isArray(data)) {
+    throw new Error('Failed to reserve LLM quota.')
   }
-  return status
+  return parseQuotaReservationResponse(data, 'LLM')
+}
+
+/** 예약을 확정한다 — succeeded=true 면 소비 유지, false 면 사용량과 overage 크레딧 환불. */
+export async function finalizeLlmQuota(
+  reservationId: string,
+  succeeded: boolean,
+  serviceRoleClient: ReturnType<typeof createClient>,
+): Promise<QuotaReservationFinalStatus> {
+  const { data, error } = await serviceRoleClient.rpc('finalize_llm_quota', {
+    p_reservation_id: reservationId,
+    p_succeeded: succeeded,
+  })
+  if (error || !data || typeof data !== 'object' || Array.isArray(data)) {
+    throw new Error('Failed to finalize LLM quota.')
+  }
+  return parseQuotaFinalizeResponse(data, 'LLM')
 }
 
 interface SubscriptionQuotaState {
@@ -151,6 +220,14 @@ async function readSubscriptionQuotaState(
   }
 }
 
+/** 구독 티어만 조회 (행이 없으면 free). 사용량은 읽지 않는다. */
+export async function readSubscriptionTier(
+  userId: string,
+  serviceRoleClient: ReturnType<typeof createClient>,
+): Promise<Tier> {
+  return (await readSubscriptionQuotaState(userId, serviceRoleClient)).tier
+}
+
 /** 기간 창(daily=오늘, weekly=오늘-6..오늘) 안의 daily_usage 합계. */
 async function readWindowUsage(
   userId: string,
diff --git a/server/supabase/functions/llm-proxy/handler.test.ts b/server/supabase/functions/llm-proxy/handler.test.ts
new file mode 100644
index 0000000..2470194
--- /dev/null
+++ b/server/supabase/functions/llm-proxy/handler.test.ts
@@ -0,0 +1,378 @@
+// Regression tests for llm-proxy:
+//  * quota is reserved before the provider call, so parallel requests past the
+//    allowance never reach Anthropic;
+//  * the provider's first-byte deadline no longer cuts off a long stream, while
+//    idle/total stream deadlines and client disconnects still stop it;
+//  * provider-side failures refund the reservation.
+import type { QuotaFeature, QuotaPeriod, QuotaReservation } from '../_shared/quota.ts'
+import {
+  createLlmProxyHandler,
+  type LlmProxyDeps,
+  type LlmQuotaStore,
+  type ProviderFetch,
+} from './handler.ts'
+import { createSseCompletionTracker } from './provider-deadline.ts'
+
+function assert(condition: boolean, message: string): asserts condition {
+  if (!condition) throw new Error(message)
+}
+
+function assertEquals<T>(actual: T, expected: T, message: string): void {
+  const a = JSON.stringify(actual)
+  const e = JSON.stringify(expected)
+  if (a !== e) throw new Error(`${message}: expected ${e}, got ${a}`)
+}
+
+const delay = (ms: number) => new Promise<void>((resolve) => setTimeout(resolve, ms))
+const encoder = new TextEncoder()
+
+/** In-memory reserve/finalize with the same in-flight semantics as reserve_llm_quota. */
+class FakeLlmQuotaStore implements LlmQuotaStore {
+  used = 0
+  reserveCalls = 0
+  finalized: Array<{ id: string; succeeded: boolean }> = []
+  private reservations = new Map<string, 'reserved' | 'completed' | 'released'>()
+  constructor(private readonly limit: number, private readonly tier: 'free' | 'pro' = 'pro') {}
+
+  readTier(): Promise<'free' | 'pro'> {
+    return Promise.resolve(this.tier)
+  }
+
+  reserve(
+    _userId: string,
+    reservationId: string,
+    _feature: QuotaFeature,
+    _baseLimit: number,
+    period: QuotaPeriod,
+  ): Promise<QuotaReservation> {
+    this.reserveCalls++
+    if (this.used >= this.limit) {
+      return Promise.resolve({
+        allowed: false, reservationId: null, status: 'denied', current: this.used, limit: this.limit,
+        period, tier: this.tier, overageCredits: 0, consumedFrom: 'none',
+      })
+    }
+    this.used++
+    this.reservations.set(reservationId, 'reserved')
+    return Promise.resolve({
+      allowed: true, reservationId, status: 'reserved', current: this.used, limit: this.limit,
+      period, tier: this.tier, overageCredits: 0, consumedFrom: 'base',
+    })
+  }
+
+  finalize(reservationId: string, succeeded: boolean): Promise<'completed' | 'released'> {
+    this.finalized.push({ id: reservationId, succeeded })
+    if (this.reservations.get(reservationId) === 'reserved' && !succeeded) this.used--
+    const status = succeeded ? 'completed' : 'released'
+    this.reservations.set(reservationId, status)
+    return Promise.resolve(status)
+  }
+}
+
+interface UpstreamPlan {
+  chunks: string[]
+  intervalMs: number
+  /** Stop producing after this many chunks and hang (no more data, no EOF). */
+  stallAfter?: number
+}
+
+/**
+ * Mock of Deno's fetch body semantics: aborting the request signal after the
+ * headers arrived errors the response body stream.
+ */
+function slowSseResponse(plan: UpstreamPlan, signal: AbortSignal): { response: Response; state: { aborted: boolean } } {
+  const state = { aborted: false }
+  let index = 0
+  let timer: ReturnType<typeof setTimeout> | null = null
+  let wake: (() => void) | null = null
+  let streamController: ReadableStreamDefaultController<Uint8Array> | null = null
+  const onAbort = () => {
+    state.aborted = true
+    if (timer !== null) clearTimeout(timer)
+    timer = null
+    wake?.()
+    try {
+      streamController?.error(signal.reason)
+    } catch {
+      // closed
+    }
+  }
+  signal.addEventListener('abort', onAbort, { once: true })
+  const body = new ReadableStream<Uint8Array>({
+    start(controller) {
+      streamController = controller
+    },
+    async pull(controller) {
+      if (state.aborted) return
+      if (plan.stallAfter !== undefined && index >= plan.stallAfter) {
+        await new Promise<void>((resolve) => {
+          wake = resolve
+        })
+        return
+      }
+      await new Promise<void>((resolve) => {
+        wake = resolve
+        timer = setTimeout(resolve, plan.intervalMs)
+      })
+      timer = null
+      if (state.aborted) return
+      if (index >= plan.chunks.length) {
+        signal.removeEventListener('abort', onAbort)
+        controller.close()
+        return
+      }
+      controller.enqueue(encoder.encode(plan.chunks[index++]))
+    },
+    cancel() {
+      if (timer !== null) clearTimeout(timer)
+      signal.removeEventListener('abort', onAbort)
+    },
+  })
+  return {
+    response: new Response(body, { status: 200, headers: { 'Content-Type': 'text/event-stream' } }),
+    state,
+  }
+}
+
+const SSE_CHUNKS = [
+  'event: message_start\ndata: {"type":"message_start"}\n\n',
+  'event: content_block_delta\ndata: {"type":"content_block_delta","delta":{"type":"text_delta","text":"1. "}}\n\n',
+  'event: content_block_delta\ndata: {"type":"content_block_delta","delta":{"type":"text_delta","text":"item"}}\n\n',
+  'event: content_block_delta\ndata: {"type":"content_block_delta","delta":{"type":"text_delta","text":" two"}}\n\n',
+  'event: message_delta\ndata: {"type":"message_delta"}\n\n',
+  'event: message_st',
+  'op\ndata: {"type":"message_stop"}\n\n',
+]
+
+function buildDeps(
+  store: FakeLlmQuotaStore,
+  fetchProvider: ProviderFetch,
+  timeouts: LlmProxyDeps['timeouts'] = {},
+): LlmProxyDeps {
+  let seq = 0
+  return {
+    authenticate: () => Promise.resolve({ id: 'user-1' }),
+    providerKey: () => 'test-key',
+    quotaStore: () => store,
+    issueGenerationReceipt: () => Promise.resolve('00000000-0000-4000-8000-000000000001'),
+    fetchProvider,
+    newReservationId: () => `res-${++seq}`,
+    timeouts,
+  }
+}
+
+function llmRequest(stream: boolean, signal?: AbortSignal): Request {
+  return new Request('http://localhost/llm-proxy', {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({
+      messages: [{ role: 'user', content: 'Write a detailed itemised summary.' }],
+      max_tokens: 2048,
+      stream,
+    }),
+    signal,
+  })
+}
+
+function okJson(): Response {
+  return new Response(JSON.stringify({ content: [{ type: 'text', text: 'hello' }] }), {
+    status: 200,
+    headers: { 'Content-Type': 'application/json' },
+  })
+}
+
+Deno.test('stream longer than the first-byte deadline is relayed in full and charged once', async () => {
+  const store = new FakeLlmQuotaStore(10)
+  const upstreams: Array<{ aborted: boolean }> = []
+  const fetchProvider: ProviderFetch = (_input, init) => {
+    const { response, state } = slowSseResponse({ chunks: SSE_CHUNKS, intervalMs: 25 }, init.signal)
+    upstreams.push(state)
+    return Promise.resolve(response)
+  }
+  // 7 chunks x 25 ms ≈ 200 ms of streaming against a 40 ms first-byte deadline.
+  const handler = createLlmProxyHandler(buildDeps(store, fetchProvider, {
+    ttfbMs: 40,
+    streamIdleMs: 500,
+    streamTotalMs: 5_000,
+  }))
+
+  const resp = await handler(llmRequest(true))
+  assertEquals(resp.status, 200, 'status')
+  const text = await resp.text()
+  assertEquals(text, SSE_CHUNKS.join(''), 'relayed body')
+  assert(upstreams.length === 1 && !upstreams[0].aborted, 'upstream must not be aborted')
+  assertEquals(store.finalized, [{ id: 'res-1', succeeded: true }], 'finalized')
+  assertEquals(store.used, 1, 'one unit spent')
+})
+
+Deno.test('stream that stalls past the idle deadline is aborted and refunded', async () => {
+  const store = new FakeLlmQuotaStore(10)
+  const upstreams: Array<{ aborted: boolean }> = []
+  const fetchProvider: ProviderFetch = (_input, init) => {
+    const { response, state } = slowSseResponse(
+      { chunks: SSE_CHUNKS, intervalMs: 5, stallAfter: 2 },
+      init.signal,
+    )
+    upstreams.push(state)
+    return Promise.resolve(response)
+  }
+  const handler = createLlmProxyHandler(buildDeps(store, fetchProvider, {
+    ttfbMs: 1_000,
+    streamIdleMs: 60,
+    streamTotalMs: 5_000,
+  }))
+
+  const resp = await handler(llmRequest(true))
+  assertEquals(resp.status, 200, 'status')
+  let errored = false
+  try {
+    await resp.text()
+  } catch (err) {
+    errored = err instanceof DOMException && err.name === 'TimeoutError'
+  }
+  assert(errored, 'client stream must error with a timeout')
+  assert(upstreams.length === 1 && upstreams[0].aborted, 'upstream must be aborted')
+  assertEquals(store.finalized, [{ id: 'res-1', succeeded: false }], 'refunded')
+  assertEquals(store.used, 0, 'unit returned')
+})
+
+Deno.test('stream that exceeds the total deadline is aborted and refunded', async () => {
+  const store = new FakeLlmQuotaStore(10)
+  const many = Array.from({ length: 200 }, () => 'event: ping\ndata: {"type":"ping"}\n\n')
+  const fetchProvider: ProviderFetch = (_input, init) =>
+    Promise.resolve(slowSseResponse({ chunks: many, intervalMs: 10 }, init.signal).response)
+  const handler = createLlmProxyHandler(buildDeps(store, fetchProvider, {
+    ttfbMs: 1_000,
+    streamIdleMs: 500,
+    streamTotalMs: 120,
+  }))
+
+  const resp = await handler(llmRequest(true))
+  let errored = false
+  try {
+    await resp.text()
+  } catch {
+    errored = true
+  }
+  assert(errored, 'client stream must error')
+  assertEquals(store.finalized, [{ id: 'res-1', succeeded: false }], 'refunded')
+})
+
+Deno.test('stream that ends without message_stop is refunded', async () => {
+  const store = new FakeLlmQuotaStore(10)
+  const fetchProvider: ProviderFetch = (_input, init) =>
+    Promise.resolve(slowSseResponse({ chunks: SSE_CHUNKS.slice(0, 3), intervalMs: 5 }, init.signal).response)
+  const handler = createLlmProxyHandler(buildDeps(store, fetchProvider, { ttfbMs: 1_000 }))
+
+  const resp = await handler(llmRequest(true))
+  await resp.text()
+  assertEquals(store.finalized, [{ id: 'res-1', succeeded: false }], 'refunded')
+})
+
+Deno.test('client disconnect cancels the upstream stream and keeps the charge', async () => {
+  const store = new FakeLlmQuotaStore(10)
+  const upstreams: Array<{ aborted: boolean }> = []
+  const fetchProvider: ProviderFetch = (_input, init) => {
+    const { response, state } = slowSseResponse({ chunks: SSE_CHUNKS, intervalMs: 20 }, init.signal)
+    upstreams.push(state)
+    return Promise.resolve(response)
+  }
+  const handler = createLlmProxyHandler(buildDeps(store, fetchProvider, { ttfbMs: 1_000 }))
+
+  const resp = await handler(llmRequest(true))
+  const reader = resp.body!.getReader()
+  await reader.read()
+  await reader.cancel('client left')
+  await delay(10)
+  assert(upstreams.length === 1 && upstreams[0].aborted, 'upstream must be aborted')
+  assertEquals(store.finalized, [{ id: 'res-1', succeeded: true }], 'charged')
+})
+
+Deno.test('parallel requests past the allowance never reach the provider', async () => {
+  const store = new FakeLlmQuotaStore(2)
+  let providerCalls = 0
+  let release: () => void = () => {}
+  const gate = new Promise<void>((resolve) => {
+    release = resolve
+  })
+  const fetchProvider: ProviderFetch = async () => {
+    providerCalls++
+    await gate
+    return okJson()
+  }
+  const handler = createLlmProxyHandler(buildDeps(store, fetchProvider))
+
+  const pending = Array.from({ length: 6 }, () => handler(llmRequest(false)))
+  await delay(10)
+  // All reservations are decided while the first two provider calls are still in flight.
+  assertEquals(providerCalls, 2, 'provider calls while in flight')
+  release()
+  const statuses = (await Promise.all(pending)).map((r) => r.status).sort()
+  assertEquals(statuses, [200, 200, 429, 429, 429, 429], 'statuses')
+  assertEquals(providerCalls, 2, 'total provider calls')
+  assertEquals(store.used, 2, 'units spent')
+})
+
+Deno.test('provider error refunds the reservation', async () => {
+  const store = new FakeLlmQuotaStore(1)
+  const fetchProvider: ProviderFetch = () =>
+    Promise.resolve(new Response('overloaded', { status: 529 }))
+  const handler = createLlmProxyHandler(buildDeps(store, fetchProvider))
+
+  const resp = await handler(llmRequest(false))
+  assertEquals(resp.status, 502, 'status')
+  await resp.body?.cancel()
+  assertEquals(store.finalized, [{ id: 'res-1', succeeded: false }], 'refunded')
+  assertEquals(store.used, 0, 'unit returned')
+})
+
+Deno.test('first-byte timeout returns 504 and refunds the reservation', async () => {
+  const store = new FakeLlmQuotaStore(1)
+  const fetchProvider: ProviderFetch = (_input, init) =>
+    new Promise<Response>((_resolve, reject) => {
+      const signal = init.signal
+      signal.addEventListener('abort', () => reject(signal.reason), { once: true })
+    })
+  const handler = createLlmProxyHandler(buildDeps(store, fetchProvider, { ttfbMs: 30 }))
+
+  const resp = await handler(llmRequest(false))
+  assertEquals(resp.status, 504, 'status')
+  assertEquals(await resp.json(), { error: 'provider_timeout' }, 'body')
+  assertEquals(store.finalized, [{ id: 'res-1', succeeded: false }], 'refunded')
+})
+
+Deno.test('denied reservation returns 429 without calling the provider', async () => {
+  const store = new FakeLlmQuotaStore(0, 'free')
+  let providerCalls = 0
+  const fetchProvider: ProviderFetch = () => {
+    providerCalls++
+    return Promise.resolve(okJson())
+  }
+  const handler = createLlmProxyHandler(buildDeps(store, fetchProvider))
+
+  const resp = await handler(llmRequest(false))
+  assertEquals(resp.status, 429, 'status')
+  const body = await resp.json()
+  assertEquals(body.error, 'quota_exceeded', 'error')
+  assertEquals(body.model, 'claude-haiku-4-5-20251001', 'model')
+  assertEquals(body.tier, 'free', 'tier')
+  assertEquals(providerCalls, 0, 'provider calls')
+})
+
+Deno.test('non-stream success settles the reservation as completed', async () => {
+  const store = new FakeLlmQuotaStore(5)
+  const handler = createLlmProxyHandler(buildDeps(store, () => Promise.resolve(okJson())))
+
+  const resp = await handler(llmRequest(false))
+  assertEquals(resp.status, 200, 'status')
+  assertEquals(await resp.json(), { content: [{ type: 'text', text: 'hello' }] }, 'body')
+  assertEquals(store.finalized, [{ id: 'res-1', succeeded: true }], 'completed')
+})
+
+Deno.test('SSE completion tracker finds message_stop split across chunks', () => {
+  const tracker = createSseCompletionTracker()
+  tracker.push(encoder.encode('event: message_st'))
+  assert(!tracker.completed, 'not yet')
+  tracker.push(encoder.encode('op\ndata: {}\n\n'))
+  assert(tracker.completed, 'completed')
+})
diff --git a/server/supabase/functions/llm-proxy/handler.ts b/server/supabase/functions/llm-proxy/handler.ts
new file mode 100644
index 0000000..c5f3454
--- /dev/null
+++ b/server/supabase/functions/llm-proxy/handler.ts
@@ -0,0 +1,336 @@
+// server/supabase/functions/llm-proxy/handler.ts
+// Use case: proxy one Anthropic Messages API call for an authenticated user.
+//
+// Order of work:
+//   1. authenticate, validate the request, resolve the tier and model
+//   2. reserve one quota unit (atomic, counts in-flight requests)
+//   3. call the provider only while holding the reservation
+//   4. settle the reservation: completed when the user received the answer,
+//      released (refunded) when the provider failed, timed out, or the stream
+//      ended before message_stop
+//
+// IO goes through ports (auth, quota store, receipt issuer, provider fetch) so
+// the quota ordering and the stream deadlines are testable without Supabase or
+// Anthropic. index.ts wires the real adapters.
+
+import { corsHeaders, handleCorsPreflightRequest } from '../_shared/cors.ts'
+import { authErrorResponse, type AuthError } from '../_shared/auth.ts'
+import {
+  getQuotaPolicy,
+  modelToQuotaKey,
+  type QuotaFeature,
+  type QuotaPeriod,
+  type QuotaReservation,
+  type QuotaReservationFinalStatus,
+  type Tier,
+} from '../_shared/quota.ts'
+import {
+  hasAssistantText,
+  LlmRequestError,
+  parseLlmRequest,
+} from '../_shared/llm-contract.ts'
+import {
+  GENERATION_ID_HEADER,
+  GENERATION_PURPOSE_HEADER,
+  GenerationReceiptError,
+  type GenerationPurpose,
+  parseGenerationPurpose,
+} from '../_shared/generation-receipt.ts'
+import { buildAnthropicSystemBlocks } from '../_shared/generative-ai-safety.ts'
+import {
+  createProviderCallDeadline,
+  DEFAULT_LLM_PROVIDER_TIMEOUTS,
+  type LlmProviderTimeouts,
+  relayProviderStream,
+  type StreamRelayOutcome,
+} from './provider-deadline.ts'
+
+export const ANTHROPIC_MESSAGES_URL = 'https://api.anthropic.com/v1/messages'
+
+/** 티어별 허용 모델 — free는 Haiku만, pro는 +Sonnet, pro_plus는 +Opus, team/enterprise는 전 모델 */
+export const TIER_MODELS: Readonly<Record<Tier, readonly string[]>> = {
+  free: ['claude-haiku-4-5-20251001'],
+  pro: ['claude-haiku-4-5-20251001', 'claude-sonnet-4-6', 'claude-opus-4-6'],
+  pro_plus: ['claude-haiku-4-5-20251001', 'claude-sonnet-4-6', 'claude-opus-4-6'],
+  team: ['claude-haiku-4-5-20251001', 'claude-sonnet-4-6', 'claude-opus-4-6'],
+  enterprise: ['claude-haiku-4-5-20251001', 'claude-sonnet-4-6', 'claude-opus-4-6'],
+}
+
+export const DEFAULT_MODEL: Readonly<Record<Tier, string>> = {
+  free: 'claude-haiku-4-5-20251001',
+  pro: 'claude-sonnet-4-6',
+  pro_plus: 'claude-sonnet-4-6',
+  team: 'claude-sonnet-4-6',
+  enterprise: 'claude-sonnet-4-6',
+}
+
+/** Port over the LLM quota tables (subscriptions, daily_usage, llm_quota_reservations). */
+export interface LlmQuotaStore {
+  readTier(userId: string): Promise<Tier>
+  reserve(
+    userId: string,
+    reservationId: string,
+    feature: QuotaFeature,
+    baseLimit: number,
+    period: QuotaPeriod,
+  ): Promise<QuotaReservation>
+  finalize(reservationId: string, succeeded: boolean): Promise<QuotaReservationFinalStatus>
+}
+
+/** Request passed to the provider port. */
+export interface ProviderRequest {
+  method: 'POST'
+  headers: Record<string, string>
+  body: string
+  signal: AbortSignal
+}
+
+/** Port over the provider HTTP call (global fetch in production). */
+export type ProviderFetch = (url: string, init: ProviderRequest) => Promise<Response>
+
+export interface LlmProxyDeps {
+  authenticate(req: Request): Promise<{ id: string }>
+  /** null when the provider key is not configured. */
+  providerKey(): string | null
+  quotaStore(): LlmQuotaStore
+  /** Issue a content-generation receipt; throws GenerationReceiptError when unavailable. */
+  issueGenerationReceipt(userId: string, purpose: GenerationPurpose, model: string): Promise<string>
+  fetchProvider?: ProviderFetch
+  newReservationId?(): string
+  timeouts?: Partial<LlmProviderTimeouts>
+}
+
+const NO_STORE_JSON = { ...corsHeaders, 'Content-Type': 'application/json', 'Cache-Control': 'no-store' }
+
+function json(status: number, body: Record<string, unknown>, noStore = true): Response {
+  return new Response(JSON.stringify(body), {
+    status,
+    headers: noStore ? NO_STORE_JSON : { ...corsHeaders, 'Content-Type': 'application/json' },
+  })
+}
+
+/** 쓰지 않을 공급자 응답 본문을 닫아 연결과 생성을 정리한다. */
+async function discardBody(resp: Response): Promise<void> {
+  if (!resp.body || resp.bodyUsed) return
+  try {
+    await resp.body.cancel()
+  } catch {
+    // 이미 닫힌 스트림 — 무시
+  }
+}
+
+function generationHeaders(generationId: string | null): Record<string, string> {
+  return generationId === null ? {} : { [GENERATION_ID_HEADER]: generationId }
+}
+
+function isAuthLikeError(err: unknown): err is AuthError {
+  return Boolean(err && typeof err === 'object' && 'status' in err && 'message' in err)
+}
+
+/**
+ * Settle a reservation exactly once. A failed finalize is logged; an unsettled
+ * reservation is released when its lease expires.
+ */
+function reservationSettler(store: LlmQuotaStore, reservationId: string): (succeeded: boolean) => Promise<void> {
+  let done = false
+  return async (succeeded: boolean) => {
+    if (done) return
+    done = true
+    try {
+      await store.finalize(reservationId, succeeded)
+    } catch {
+      console.error('LLM quota finalization failed', { succeeded })
+    }
+  }
+}
+
+export function createLlmProxyHandler(deps: LlmProxyDeps): (req: Request) => Promise<Response> {
+  const fetchProvider: ProviderFetch = deps.fetchProvider ?? ((url, init) => fetch(url, init))
+  const newReservationId = deps.newReservationId ?? (() => crypto.randomUUID())
+  const timeouts: LlmProviderTimeouts = { ...DEFAULT_LLM_PROVIDER_TIMEOUTS, ...deps.timeouts }
+
+  return async (req: Request): Promise<Response> => {
+    const preflight = handleCorsPreflightRequest(req)
+    if (preflight) return preflight
+
+    if (req.method !== 'POST') {
+      return json(405, { error: 'Method not allowed' }, false)
+    }
+
+    let settleReservation: ((succeeded: boolean) => Promise<void>) | null = null
+    try {
+      const user = await deps.authenticate(req)
+
+      let rawBody: unknown
+      try {
+        rawBody = await req.json()
+      } catch {
+        throw new LlmRequestError('Invalid JSON body')
+      }
+      const body = parseLlmRequest(rawBody)
+      const generationPurpose = parseGenerationPurpose(req.headers.get(GENERATION_PURPOSE_HEADER))
+
+      // A deployment without a provider must not consume quota or fabricate an answer.
+      const anthropicKey = deps.providerKey()
+      if (!anthropicKey) return json(503, { error: 'provider_unavailable' })
+
+      const quota = deps.quotaStore()
+
+      // 1단계: 티어 조회 + 모델 검증
+      const tier = await quota.readTier(user.id)
+      const requestedModel = body.model ?? DEFAULT_MODEL[tier]
+      if (!TIER_MODELS[tier].includes(requestedModel)) {
+        return json(403, {
+          error: 'model_not_allowed',
+          tier,
+          requested: requestedModel,
+          allowed: TIER_MODELS[tier],
+        }, false)
+      }
+
+      // 2단계: 공급자 호출 전에 쿼터 한 단위를 원자적으로 예약한다.
+      // 진행 중인 요청도 사용량에 포함되므로 병렬 요청이 한도를 넘어 공급자 비용을 쓰지 못한다.
+      const quotaKey = modelToQuotaKey(requestedModel)
+      const policy = getQuotaPolicy(tier, quotaKey)
+      const reservation = await quota.reserve(
+        user.id,
+        newReservationId(),
+        quotaKey,
+        policy.limit,
+        policy.period,
+      )
+      if (!reservation.allowed || reservation.reservationId === null) {
+        return json(429, {
+          error: 'quota_exceeded',
+          model: requestedModel,
+          current: reservation.current,
+          limit: reservation.limit,
+          period: reservation.period,
+          tier: reservation.tier,
+          overage_credits: reservation.overageCredits,
+        }, false)
+      }
+      const settle = reservationSettler(quota, reservation.reservationId)
+      settleReservation = settle
+
+      // 3단계: 공급자 호출 (Prompt Caching 2024-07-31 활성화).
+      // 공급자 5xx/과부하/타임아웃으로 답을 주지 못한 요청은 예약을 해제(환불)한다.
+      const deadline = createProviderCallDeadline(timeouts.ttfbMs, req.signal)
+      let anthropicResp: Response
+      try {
+        anthropicResp = await fetchProvider(ANTHROPIC_MESSAGES_URL, {
+          method: 'POST',
+          headers: {
+            'Content-Type': 'application/json',
+            'x-api-key': anthropicKey,
+            'anthropic-version': '2023-06-01',
+            'anthropic-beta': 'prompt-caching-2024-07-31',
+          },
+          body: JSON.stringify({
+            model: requestedModel,
+            max_tokens: body.max_tokens,
+            system: buildAnthropicSystemBlocks(body.system),
+            messages: body.messages,
+            stream: body.stream,
+          }),
+          signal: deadline.signal,
+        })
+      } catch (err) {
+        deadline.dispose()
+        throw err
+      }
+
+      if (!anthropicResp.ok) {
+        deadline.dispose()
+        console.error('Anthropic request failed', { status: anthropicResp.status })
+        await discardBody(anthropicResp)
+        await settle(false)
+        return json(502, { error: 'provider_request_failed' })
+      }
+
+      if (body.stream && anthropicResp.body) {
+        // The first-byte deadline covers the provider call only; the streamed
+        // body gets its own idle/total deadlines.
+        deadline.headersReceived()
+        let generationId: string | null
+        try {
+          generationId = generationPurpose === null
+            ? null
+            : await deps.issueGenerationReceipt(user.id, generationPurpose, requestedModel)
+        } catch (err) {
+          deadline.abort(err)
+          deadline.dispose()
+          await discardBody(anthropicResp)
+          throw err
+        }
+        const relayed = relayProviderStream(anthropicResp.body, {
+          idleMs: timeouts.streamIdleMs,
+          totalMs: timeouts.streamTotalMs,
+          abortUpstream: (reason) => deadline.abort(reason),
+          onSettled: async (outcome: StreamRelayOutcome) => {
+            deadline.dispose()
+            if (outcome === 'failed') console.error('Anthropic stream did not complete')
+            // A client that stops reading keeps the charge: the provider already
+            // generated what was sent. Only provider-side failures are refunded.
+            await settle(outcome !== 'failed')
+          },
+        })
+        return new Response(relayed, {
+          status: 200,
+          headers: {
+            ...corsHeaders,
+            ...generationHeaders(generationId),
+            'Content-Type': 'text/event-stream',
+            'Cache-Control': 'no-store',
+            Connection: 'keep-alive',
+          },
+        })
+      }
+
+      // 비스트리밍: 본문 전체가 답이므로 첫 바이트 기한을 본문 읽기까지 유지한다.
+      let nonStreamData: unknown
+      try {
+        nonStreamData = await anthropicResp.json()
+      } finally {
+        deadline.dispose()
+      }
+      if (!hasAssistantText(nonStreamData)) {
+        console.error('Anthropic returned an invalid response shape')
+        await settle(false)
+        return json(502, { error: 'provider_invalid_response' })
+      }
+
+      const generationId = generationPurpose === null
+        ? null
+        : await deps.issueGenerationReceipt(user.id, generationPurpose, requestedModel)
+      await settle(true)
+      return new Response(JSON.stringify(nonStreamData), {
+        status: 200,
+        headers: {
+          ...corsHeaders,
+          ...generationHeaders(generationId),
+          'Content-Type': 'application/json',
+          'Cache-Control': 'no-store',
+        },
+      })
+    } catch (err) {
+      // Anything that failed while a reservation was held gives the unit back.
+      await settleReservation?.(false)
+      if (err instanceof GenerationReceiptError) {
+        const invalidPurpose = err.code === 'invalid_generation_purpose'
+        return json(invalidPurpose ? 400 : 503, {
+          error: invalidPurpose ? 'invalid_request' : 'generation_receipt_unavailable',
+        })
+      }
+      if (err instanceof LlmRequestError) {
+        return json(err.status, { error: 'invalid_request', message: err.message })
+      }
+      if (isAuthLikeError(err)) {
+        return authErrorResponse(err, corsHeaders)
+      }
+      const timedOut = err instanceof DOMException && err.name === 'TimeoutError'
+      console.error('llm-proxy failed', { kind: timedOut ? 'provider_timeout' : 'internal_error' })
+      return json(timedOut ? 504 : 500, { error: timedOut ? 'provider_timeout' : 'internal_error' })
+    }
+  }
+}
diff --git a/server/supabase/functions/llm-proxy/index.ts b/server/supabase/functions/llm-proxy/index.ts
index e5870c0..57034b4 100644
--- a/server/supabase/functions/llm-proxy/index.ts
+++ b/server/supabase/functions/llm-proxy/index.ts
@@ -1,293 +1,50 @@
 // server/supabase/functions/llm-proxy/index.ts
-// Anthropic Claude Messages API 프록시.
+// Anthropic Claude Messages API 프록시 — composition root.
 // Phase 3.2: 모델별 쿼터 (Haiku/Sonnet/Opus × Free/Pro/Pro+)
 // 요청: application/json { messages, system?, max_tokens?, model? }
 // 응답: JSON (non-stream) 또는 SSE (stream=true)
+// 유스케이스와 쿼터/기한 규칙은 handler.ts, 공급자 기한은 provider-deadline.ts 에 있다.
 
-import { corsHeaders, handleCorsPreflightRequest } from '../_shared/cors.ts'
-import { requireUser, authErrorResponse, type AuthError } from '../_shared/auth.ts'
+import { requireUser } from '../_shared/auth.ts'
 import {
-  checkQuota,
-  consumeQuota,
   createServiceRoleClient,
-  modelToQuotaKey,
-  getQuotaPolicy,
-  type Tier,
+  finalizeLlmQuota,
+  readSubscriptionTier,
+  reserveLlmQuota,
 } from '../_shared/quota.ts'
-import {
-  hasAssistantText,
-  LlmRequestError,
-  parseLlmRequest,
-} from '../_shared/llm-contract.ts'
-import {
-  GENERATION_ID_HEADER,
-  GENERATION_PURPOSE_HEADER,
-  GenerationReceiptError,
-  parseGenerationPurpose,
-  parseGenerationReceiptId,
-  type GenerationPurpose,
-} from '../_shared/generation-receipt.ts'
-import { buildAnthropicSystemBlocks } from '../_shared/generative-ai-safety.ts'
+import { GenerationReceiptError, parseGenerationReceiptId } from '../_shared/generation-receipt.ts'
 import { readProviderKey } from '../_shared/provider-key.ts'
+import { createLlmProxyHandler, type LlmQuotaStore } from './handler.ts'
 
-/** 티어별 허용 모델 — free는 Haiku만, pro는 +Sonnet, pro_plus는 +Opus, team/enterprise는 전 모델 */
-const TIER_MODELS: Record<Tier, string[]> = {
-  free: ['claude-haiku-4-5-20251001'],
-  pro: ['claude-haiku-4-5-20251001', 'claude-sonnet-4-6', 'claude-opus-4-6'],
-  pro_plus: ['claude-haiku-4-5-20251001', 'claude-sonnet-4-6', 'claude-opus-4-6'],
-  team: ['claude-haiku-4-5-20251001', 'claude-sonnet-4-6', 'claude-opus-4-6'],
-  enterprise: ['claude-haiku-4-5-20251001', 'claude-sonnet-4-6', 'claude-opus-4-6'],
+let serviceClient: ReturnType<typeof createServiceRoleClient> | null = null
+function service(): ReturnType<typeof createServiceRoleClient> {
+  serviceClient ??= createServiceRoleClient()
+  return serviceClient
 }
 
-const DEFAULT_MODEL: Record<Tier, string> = {
-  free: 'claude-haiku-4-5-20251001',
-  pro: 'claude-sonnet-4-6',
-  pro_plus: 'claude-sonnet-4-6',
-  team: 'claude-sonnet-4-6',
-  enterprise: 'claude-sonnet-4-6',
-}
-
-async function issueGenerationReceipt(
-  serviceClient: ReturnType<typeof createServiceRoleClient>,
-  userId: string,
-  purpose: GenerationPurpose | null,
-  model: string,
-): Promise<string | null> {
-  if (purpose === null) return null
-  const { data, error } = await serviceClient.rpc('issue_content_generation_receipt_v1', {
-    p_actor_id: userId,
-    p_purpose: purpose,
-    p_model: model,
-  })
-  if (error) {
-    console.error('Generation receipt issuance failed', { code: error.code ?? 'unknown' })
-    throw new GenerationReceiptError('generation_receipt_unavailable')
-  }
-  return parseGenerationReceiptId(data)
-}
-
-/** 쓰지 않을 공급자 응답 본문을 닫아 연결과 생성을 정리한다. */
-async function discardBody(resp: Response): Promise<void> {
-  if (!resp.body || resp.bodyUsed) return
-  try {
-    await resp.body.cancel()
-  } catch {
-    // 이미 닫힌 스트림 — 무시
+function supabaseLlmQuotaStore(client: ReturnType<typeof createServiceRoleClient>): LlmQuotaStore {
+  return {
+    readTier: (userId) => readSubscriptionTier(userId, client),
+    reserve: (userId, reservationId, feature, baseLimit, period) =>
+      reserveLlmQuota(userId, reservationId, feature, baseLimit, period, client),
+    finalize: (reservationId, succeeded) => finalizeLlmQuota(reservationId, succeeded, client),
   }
 }
 
-function generationHeaders(generationId: string | null): Record<string, string> {
-  return generationId === null ? {} : { [GENERATION_ID_HEADER]: generationId }
-}
-
-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' },
+Deno.serve(createLlmProxyHandler({
+  authenticate: requireUser,
+  providerKey: () => readProviderKey('ANTHROPIC_API_KEY'),
+  quotaStore: () => supabaseLlmQuotaStore(service()),
+  issueGenerationReceipt: async (userId, purpose, model) => {
+    const { data, error } = await service().rpc('issue_content_generation_receipt_v1', {
+      p_actor_id: userId,
+      p_purpose: purpose,
+      p_model: model,
     })
-  }
-
-  try {
-    const user = await requireUser(req)
-    const serviceClient = createServiceRoleClient()
-
-    let rawBody: unknown
-    try {
-      rawBody = await req.json()
-    } catch {
-      throw new LlmRequestError('Invalid JSON body')
+    if (error) {
+      console.error('Generation receipt issuance failed', { code: error.code ?? 'unknown' })
+      throw new GenerationReceiptError('generation_receipt_unavailable')
     }
-    const body = parseLlmRequest(rawBody)
-    const generationPurpose = parseGenerationPurpose(
-      req.headers.get(GENERATION_PURPOSE_HEADER),
-    )
-
-    // A deployment without a provider must not consume quota or fabricate an answer.
-    const anthropicKey = readProviderKey('ANTHROPIC_API_KEY')
-    if (!anthropicKey) {
-      return new Response(JSON.stringify({ error: 'provider_unavailable' }), {
-        status: 503,
-        headers: { ...corsHeaders, 'Content-Type': 'application/json', 'Cache-Control': 'no-store' },
-      })
-    }
-
-    // 1단계: 티어 조회 (어떤 모델이든 한 번만 읽으면 됨 — haiku로 대리 조회)
-    const tierCheck = await checkQuota(user.id, 'llm_haiku', serviceClient)
-    const tier = tierCheck.tier
-
-    // 모델 선택 + 티어 검증
-    const requestedModel = body.model ?? DEFAULT_MODEL[tier]
-    if (!TIER_MODELS[tier].includes(requestedModel)) {
-      return new Response(
-        JSON.stringify({
-          error: 'model_not_allowed',
-          tier,
-          requested: requestedModel,
-          allowed: TIER_MODELS[tier],
-        }),
-        {
-          status: 403,
-          headers: { ...corsHeaders, 'Content-Type': 'application/json' },
-        },
-      )
-    }
-
-    // 2단계: 해당 모델의 쿼터 확인 (모델별 일간/주간)
-    const quotaKey = modelToQuotaKey(requestedModel)
-    const modelQuota = await checkQuota(user.id, quotaKey, serviceClient)
-    if (!modelQuota.allowed) {
-      return new Response(
-        JSON.stringify({
-          error: 'quota_exceeded',
-          model: requestedModel,
-          current: modelQuota.current,
-          limit: modelQuota.limit,
-          period: modelQuota.period,
-          tier,
-          overage_credits: modelQuota.overageCredits,
-        }),
-        {
-          status: 429,
-          headers: { ...corsHeaders, 'Content-Type': 'application/json' },
-        },
-      )
-    }
-
-    // 3단계: 공급자 호출 (Prompt Caching 2024-07-31 활성화)
-    // 쿼터는 공급자가 요청을 받아들인 뒤에만 소비한다. 공급자 5xx/과부하/타임아웃으로
-    // 답을 주지 못한 요청이 쿼터를 깎고, 클라이언트 재시도가 한 번 더 깎는 일을 막는다.
-    const systemPayload = buildAnthropicSystemBlocks(body.system)
-
-    const anthropicResp = await fetch('https://api.anthropic.com/v1/messages', {
-      method: 'POST',
-      headers: {
-        'Content-Type': 'application/json',
-        'x-api-key': anthropicKey,
-        'anthropic-version': '2023-06-01',
-        'anthropic-beta': 'prompt-caching-2024-07-31',
-      },
-      body: JSON.stringify({
-        model: requestedModel,
-        max_tokens: body.max_tokens,
-        system: systemPayload,
-        messages: body.messages,
-        stream: body.stream,
-      }),
-      signal: AbortSignal.timeout(45_000),
-    })
-
-    if (!anthropicResp.ok) {
-      console.error('Anthropic request failed', { status: anthropicResp.status })
-      await discardBody(anthropicResp)
-      return new Response(JSON.stringify({ error: 'provider_request_failed' }), {
-        status: 502,
-        headers: { ...corsHeaders, 'Content-Type': 'application/json', 'Cache-Control': 'no-store' },
-      })
-    }
-
-    // 비스트리밍 응답은 형식 검증까지 통과한 뒤에 소비한다.
-    let nonStreamData: unknown = null
-    if (!body.stream || !anthropicResp.body) {
-      nonStreamData = await anthropicResp.json()
-      if (!hasAssistantText(nonStreamData)) {
-        console.error('Anthropic returned an invalid response shape')
-        return new Response(JSON.stringify({ error: 'provider_invalid_response' }), {
-          status: 502,
-          headers: { ...corsHeaders, 'Content-Type': 'application/json', 'Cache-Control': 'no-store' },
-        })
-      }
-    }
-
-    // 4단계: 쿼터 소비 (원자적 base → overage fallback).
-    // 동시 요청이 checkQuota 를 함께 통과했다면 여기서 초과분이 거절된다.
-    const policy = getQuotaPolicy(tier, quotaKey)
-    let consume: Awaited<ReturnType<typeof consumeQuota>>
-    try {
-      consume = await consumeQuota(user.id, quotaKey, serviceClient, policy.limit)
-    } catch (err) {
-      await discardBody(anthropicResp)
-      throw err
-    }
-    if (!consume.allowed) {
-      await discardBody(anthropicResp)
-      return new Response(
-        JSON.stringify({
-          error: 'quota_exceeded',
-          model: requestedModel,
-          current: consume.current,
-          limit: consume.limit,
-          tier,
-          overage_credits: consume.overageCredits,
-        }),
-        {
-          status: 429,
-          headers: { ...corsHeaders, 'Content-Type': 'application/json' },
-        },
-      )
-    }
-
-    if (body.stream && anthropicResp.body) {
-      const generationId = await issueGenerationReceipt(
-        serviceClient,
-        user.id,
-        generationPurpose,
-        requestedModel,
-      )
-      return new Response(anthropicResp.body, {
-        status: 200,
-        headers: {
-          ...corsHeaders,
-          ...generationHeaders(generationId),
-          'Content-Type': 'text/event-stream',
-          'Cache-Control': 'no-store',
-          Connection: 'keep-alive',
-        },
-      })
-    }
-
-    const generationId = await issueGenerationReceipt(
-      serviceClient,
-      user.id,
-      generationPurpose,
-      requestedModel,
-    )
-    return new Response(JSON.stringify(nonStreamData), {
-      status: 200,
-      headers: {
-        ...corsHeaders,
-        ...generationHeaders(generationId),
-        'Content-Type': 'application/json',
-        'Cache-Control': 'no-store',
-      },
-    })
-  } catch (err) {
-    if (err instanceof GenerationReceiptError) {
-      const invalidPurpose = err.code === 'invalid_generation_purpose'
-      return new Response(JSON.stringify({
-        error: invalidPurpose ? 'invalid_request' : 'generation_receipt_unavailable',
-      }), {
-        status: invalidPurpose ? 400 : 503,
-        headers: { ...corsHeaders, 'Content-Type': 'application/json', 'Cache-Control': 'no-store' },
-      })
-    }
-    if (err instanceof LlmRequestError) {
-      return new Response(JSON.stringify({ error: 'invalid_request', message: err.message }), {
-        status: err.status,
-        headers: { ...corsHeaders, 'Content-Type': 'application/json', 'Cache-Control': 'no-store' },
-      })
-    }
-    if (err && typeof err === 'object' && 'status' in err && 'message' in err) {
-      return authErrorResponse(err as AuthError, corsHeaders)
-    }
-    const timedOut = err instanceof DOMException && err.name === 'TimeoutError'
-    console.error('llm-proxy failed', { kind: timedOut ? 'provider_timeout' : 'internal_error' })
-    return new Response(JSON.stringify({ error: timedOut ? 'provider_timeout' : 'internal_error' }), {
-      status: timedOut ? 504 : 500,
-      headers: { ...corsHeaders, 'Content-Type': 'application/json', 'Cache-Control': 'no-store' },
-    })
-  }
-})
+    return parseGenerationReceiptId(data)
+  },
+}))
diff --git a/server/supabase/functions/llm-proxy/provider-deadline.ts b/server/supabase/functions/llm-proxy/provider-deadline.ts
new file mode 100644
index 0000000..c9c5fde
--- /dev/null
+++ b/server/supabase/functions/llm-proxy/provider-deadline.ts
@@ -0,0 +1,226 @@
+// server/supabase/functions/llm-proxy/provider-deadline.ts
+// Deadlines for the Anthropic call, split by phase.
+//
+// A single AbortSignal.timeout(45 s) on fetch also errors the response body,
+// so it used to cut off streamed answers that took longer than 45 s in total.
+// The phases now have their own limits:
+//   * time to first byte (response headers): ttfbMs — covers the provider call.
+//     For non-stream requests the whole body is the answer, so the deadline
+//     stays armed until the JSON has been read.
+//   * streamed body: an idle limit between chunks and a total limit for the
+//     stream, sized for a max_tokens=4096 answer.
+// The client's request signal is tied in, so a client that disconnects cancels
+// the upstream generation instead of letting it run to completion.
+
+export interface LlmProviderTimeouts {
+  /** Response headers must arrive within this time. */
+  ttfbMs: number
+  /** Longest gap allowed between two streamed chunks. */
+  streamIdleMs: number
+  /** Longest a streamed body may run after the headers arrived. */
+  streamTotalMs: number
+}
+
+export const DEFAULT_LLM_PROVIDER_TIMEOUTS: Readonly<LlmProviderTimeouts> = Object.freeze({
+  ttfbMs: 45_000,
+  streamIdleMs: 30_000,
+  streamTotalMs: 180_000,
+})
+
+export function providerTimeoutError(message: string): DOMException {
+  return new DOMException(message, 'TimeoutError')
+}
+
+export interface ProviderCallDeadline {
+  /** Pass to fetch; aborts on the first-byte deadline, a stream deadline or a client disconnect. */
+  readonly signal: AbortSignal
+  /** Stop the first-byte timer (the response headers arrived). */
+  headersReceived(): void
+  abort(reason: unknown): void
+  /** Clear timers and listeners. Safe to call more than once. */
+  dispose(): void
+}
+
+export function createProviderCallDeadline(
+  ttfbMs: number,
+  clientSignal: AbortSignal | null,
+): ProviderCallDeadline {
+  const controller = new AbortController()
+  let ttfbTimer: ReturnType<typeof setTimeout> | null = setTimeout(() => {
+    ttfbTimer = null
+    controller.abort(providerTimeoutError('provider response timeout'))
+  }, ttfbMs)
+
+  const onClientAbort = (): void => {
+    controller.abort(clientSignal?.reason ?? new DOMException('client disconnected', 'AbortError'))
+  }
+  if (clientSignal?.aborted) onClientAbort()
+  else clientSignal?.addEventListener('abort', onClientAbort, { once: true })
+
+  const clearTtfb = (): void => {
+    if (ttfbTimer !== null) clearTimeout(ttfbTimer)
+    ttfbTimer = null
+  }
+
+  return {
+    signal: controller.signal,
+    headersReceived: clearTtfb,
+    abort(reason: unknown): void {
+      controller.abort(reason)
+    },
+    dispose(): void {
+      clearTtfb()
+      clientSignal?.removeEventListener('abort', onClientAbort)
+    },
+  }
+}
+
+/**
+ * Tracks whether an Anthropic SSE stream reached `message_stop`.
+ * Chunks can split the marker, so a short tail of the previous text is kept.
+ */
+export function createSseCompletionTracker(): {
+  push(chunk: Uint8Array): void
+  readonly completed: boolean
+} {
+  const MARKER = 'message_stop'
+  const decoder = new TextDecoder()
+  let tail = ''
+  let completed = false
+  return {
+    push(chunk: Uint8Array): void {
+      if (completed) return
+      const text = tail + decoder.decode(chunk, { stream: true })
+      if (text.includes(MARKER)) {
+        completed = true
+        tail = ''
+        return
+      }
+      tail = text.slice(-(MARKER.length - 1))
+    },
+    get completed(): boolean {
+      return completed
+    },
+  }
+}
+
+/** How a relayed stream ended. */
+export type StreamRelayOutcome =
+  /** Upstream ended after message_stop: the client received the full answer. */
+  | 'completed'
+  /** Upstream errored, timed out, or ended without message_stop. */
+  | 'failed'
+  /** The client stopped reading (disconnect/cancel). */
+  | 'cancelled'
+
+export interface StreamRelayOptions {
+  idleMs: number
+  totalMs: number
+  /** Abort the upstream request (fetch signal). */
+  abortUpstream(reason: unknown): void
+  /** Called exactly once when the relay ends. Awaited before the client stream closes or errors. */
+  onSettled(outcome: StreamRelayOutcome): Promise<void>
+}
+
+/**
+ * Relay a provider SSE body to the client with an idle deadline between
+ * chunks and a total deadline for the whole stream.
+ */
+export function relayProviderStream(
+  upstream: ReadableStream<Uint8Array>,
+  options: StreamRelayOptions,
+): ReadableStream<Uint8Array> {
+  const reader = upstream.getReader()
+  const tracker = createSseCompletionTracker()
+  let settled = false
+  let totalTimer: ReturnType<typeof setTimeout> | null = null
+  let idleTimer: ReturnType<typeof setTimeout> | null = null
+  let rejectIdle: ((reason: unknown) => void) | null = null
+  let downstream: ReadableStreamDefaultController<Uint8Array> | null = null
+
+  const clearTimers = (): void => {
+    if (totalTimer !== null) clearTimeout(totalTimer)
+    if (idleTimer !== null) clearTimeout(idleTimer)
+    totalTimer = null
+    idleTimer = null
+  }
+
+  const settle = async (outcome: StreamRelayOutcome): Promise<boolean> => {
+    if (settled) return false
+    settled = true
+    clearTimers()
+    try {
+      await options.onSettled(outcome)
+    } catch {
+      // Settlement is best effort; the caller logs its own failures.
+    }
+    return true
+  }
+
+  const terminate = async (reason: unknown): Promise<void> => {
+    if (settled) return
+    options.abortUpstream(reason)
+    reader.cancel(reason).catch(() => undefined)
+    rejectIdle?.(reason)
+    if (await settle('failed')) {
+      try {
+        downstream?.error(reason)
+      } catch {
+        // Already closed.
+      }
+    }
+  }
+
+  const readWithIdleDeadline = (): Promise<ReadableStreamReadResult<Uint8Array>> =>
+    new Promise((resolve, reject) => {
+      rejectIdle = reject
+      idleTimer = setTimeout(() => {
+        idleTimer = null
+        void terminate(providerTimeoutError('provider stream idle timeout'))
+      }, options.idleMs)
+      reader.read().then(resolve, reject).finally(() => {
+        if (idleTimer !== null) clearTimeout(idleTimer)
+        idleTimer = null
+        rejectIdle = null
+      })
+    })
+
+  return new ReadableStream<Uint8Array>({
+    start(controller) {
+      downstream = controller
+      // Also fires while the client applies backpressure and no read is pending.
+      totalTimer = setTimeout(() => {
+        totalTimer = null
+        void terminate(providerTimeoutError('provider stream total timeout'))
+      }, options.totalMs)
+    },
+    async pull(controller) {
+      if (settled) return
+      let result: ReadableStreamReadResult<Uint8Array>
+      try {
+        result = await readWithIdleDeadline()
+      } catch (err) {
+        if (settled) return
+        options.abortUpstream(err)
+        if (await settle('failed')) controller.error(err)
+        return
+      }
+      if (settled) return
+      if (result.done) {
+        const outcome: StreamRelayOutcome = tracker.completed ? 'completed' : 'failed'
+        // A stream that ended without message_stop is still closed cleanly: the
+        // client already treats a missing message_stop as incomplete, and any
+        // in-band `event: error` the provider sent stays readable.
+        if (await settle(outcome)) controller.close()
+        return
+      }
+      tracker.push(result.value)
+      controller.enqueue(result.value)
+    },
+    async cancel(reason) {
+      options.abortUpstream(reason)
+      reader.cancel(reason).catch(() => undefined)
+      await settle('cancelled')
+    },
+  })
+}
diff --git a/server/supabase/migrations/20260928020800_llm_quota_reservations.sql b/server/supabase/migrations/20260928020800_llm_quota_reservations.sql
new file mode 100644
index 0000000..aeb45f2
--- /dev/null
+++ b/server/supabase/migrations/20260928020800_llm_quota_reservations.sql
@@ -0,0 +1,296 @@
+-- llm-proxy: reserve LLM quota before calling the provider.
+--
+-- llm-proxy used to run a read-only checkQuota (a SELECT on daily_usage),
+-- call Anthropic, and only then charge with consume_quota. Nothing counted
+-- requests that were still in flight, so N parallel requests from one user all
+-- passed the pre-check and each paid for a full Anthropic generation before
+-- consume_quota rejected every request past the allowance and threw the paid
+-- reply away (the same flaw 20260928000037 fixed for meeting documents).
+--
+-- reserve_llm_quota now takes one unit up front, under the same
+-- per-user/per-feature advisory lock that consume_quota uses, and records it
+-- in daily_usage immediately, so a concurrent request (or a consume_quota
+-- call for the same feature) sees it. The edge function calls the provider
+-- only while it holds a reservation, then settles it:
+--   * finalize_llm_quota(id, true)  -> 'completed' (the unit stays spent)
+--   * finalize_llm_quota(id, false) -> 'released'  (daily_usage -1, and the
+--     overage credit is returned when the unit came from overage)
+-- A crashed worker cannot hold a unit forever: reservations whose 10 minute
+-- lease has expired are released by the next reserve call for that
+-- user/feature, well beyond the proxy's 45 s time-to-first-byte and 180 s
+-- stream deadlines.
+--
+-- p_base_limit / p_period come from PLAN_QUOTA (packages/core plan catalog),
+-- exactly like consume_quota. Only service_role may call these functions.
+-- Apply this migration before deploying the llm-proxy that calls it.
+
+CREATE TABLE IF NOT EXISTS public.llm_quota_reservations (
+  id uuid PRIMARY KEY,
+  user_id uuid NOT NULL REFERENCES auth.users(id) ON DELETE CASCADE,
+  feature text NOT NULL CHECK (feature IN ('llm_haiku', 'llm_sonnet', 'llm_opus')),
+  usage_date date NOT NULL DEFAULT CURRENT_DATE,
+  consumed_from text NOT NULL CHECK (consumed_from IN ('base', 'overage', 'unlimited')),
+  status text NOT NULL DEFAULT 'reserved' CHECK (status IN ('reserved', 'completed', 'released')),
+  tier text NOT NULL,
+  quota_period text NOT NULL CHECK (quota_period IN ('daily', 'weekly')),
+  quota_limit integer NOT NULL,
+  current_count integer NOT NULL,
+  overage_after integer NOT NULL,
+  lease_expires_at timestamptz NOT NULL,
+  created_at timestamptz NOT NULL DEFAULT now(),
+  finalized_at timestamptz,
+  release_reason text
+);
+
+ALTER TABLE public.llm_quota_reservations ENABLE ROW LEVEL SECURITY;
+REVOKE ALL ON TABLE public.llm_quota_reservations FROM PUBLIC, anon, authenticated;
+GRANT SELECT, INSERT, UPDATE, DELETE ON TABLE public.llm_quota_reservations TO service_role;
+
+CREATE INDEX IF NOT EXISTS idx_llm_quota_reservations_reclaim
+  ON public.llm_quota_reservations(user_id, feature, lease_expires_at)
+  WHERE status = 'reserved';
+
+CREATE OR REPLACE FUNCTION public.reserve_llm_quota(
+  p_user_id uuid,
+  p_reservation_id uuid,
+  p_feature text,
+  p_base_limit integer,
+  p_period text
+) RETURNS jsonb
+LANGUAGE plpgsql
+SECURITY DEFINER
+SET search_path = public, pg_temp
+AS $$
+DECLARE
+  existing public.llm_quota_reservations%ROWTYPE;
+  expired public.llm_quota_reservations%ROWTYPE;
+  subscription_tier text := 'free';
+  overage integer := 0;
+  new_overage integer;
+  current_count integer := 0;
+  consumed_from text;
+BEGIN
+  IF p_user_id IS NULL
+     OR p_reservation_id IS NULL
+     OR p_feature IS NULL
+     OR p_feature NOT IN ('llm_haiku', 'llm_sonnet', 'llm_opus')
+     OR p_base_limit IS NULL
+     OR p_base_limit < -1
+     OR p_period IS NULL
+     OR p_period NOT IN ('daily', 'weekly') THEN
+    RAISE EXCEPTION 'invalid_llm_quota_reservation' USING ERRCODE = '22023';
+  END IF;
+
+  -- Same lock key as consume_quota so both paths serialise per user/feature.
+  PERFORM pg_advisory_xact_lock(hashtextextended(p_user_id::text || ':' || p_feature, 20260928));
+
+  SELECT * INTO existing
+  FROM public.llm_quota_reservations
+  WHERE id = p_reservation_id
+  FOR UPDATE;
+
+  IF FOUND THEN
+    IF existing.user_id <> p_user_id OR existing.feature <> p_feature THEN
+      RAISE EXCEPTION 'llm_quota_reservation_conflict' USING ERRCODE = 'PT409';
+    END IF;
+    RETURN jsonb_build_object(
+      'allowed', existing.status IN ('reserved', 'completed'),
+      'reservation_id', existing.id,
+      'status', existing.status,
+      'current', existing.current_count,
+      'limit', existing.quota_limit,
+      'period', existing.quota_period,
+      'tier', existing.tier,
+      'overage_credits', existing.overage_after,
+      'consumed_from', existing.consumed_from
+    );
+  END IF;
+
+  -- Reclaim crashed requests before calculating the next allowance.
+  FOR expired IN
+    SELECT *
+    FROM public.llm_quota_reservations
+    WHERE user_id = p_user_id
+      AND feature = p_feature
+      AND status = 'reserved'
+      AND lease_expires_at <= now()
+    FOR UPDATE
+  LOOP
+    UPDATE public.daily_usage
+    SET count = greatest(count - 1, 0)
+    WHERE user_id = expired.user_id
+      AND date = expired.usage_date
+      AND feature = expired.feature;
+
+    IF expired.consumed_from = 'overage' THEN
+      UPDATE public.subscriptions
+      SET overage_credits = overage_credits + 1,
+          updated_at = now()
+      WHERE user_id = expired.user_id;
+    END IF;
+
+    UPDATE public.llm_quota_reservations
+    SET status = 'released', finalized_at = now(), release_reason = 'lease_expired'
+    WHERE id = expired.id;
+  END LOOP;
+
+  SELECT coalesce(tier, 'free'), coalesce(overage_credits, 0)
+  INTO subscription_tier, overage
+  FROM public.subscriptions
+  WHERE user_id = p_user_id
+  FOR UPDATE;
+
+  IF NOT FOUND THEN
+    subscription_tier := 'free';
+    overage := 0;
+  END IF;
+
+  -- Not available: never spend credits on a model the tier does not include.
+  IF p_base_limit = 0 THEN
+    RETURN jsonb_build_object(
+      'allowed', false,
+      'reservation_id', NULL,
+      'status', 'denied',
+      'current', 0,
+      'limit', 0,
+      'period', p_period,
+      'tier', subscription_tier,
+      'overage_credits', overage,
+      'consumed_from', 'none'
+    );
+  END IF;
+
+  -- daily_usage already includes units held by in-flight reservations.
+  SELECT coalesce(sum(count), 0)::integer INTO current_count
+  FROM public.daily_usage
+  WHERE user_id = p_user_id
+    AND feature = p_feature
+    AND date >= CASE WHEN p_period = 'weekly' THEN CURRENT_DATE - 6 ELSE CURRENT_DATE END
+    AND date <= CURRENT_DATE;
+
+  IF p_base_limit = -1 THEN
+    consumed_from := 'unlimited';
+  ELSIF current_count < p_base_limit THEN
+    consumed_from := 'base';
+  ELSE
+    UPDATE public.subscriptions
+    SET overage_credits = overage_credits - 1,
+        updated_at = now()
+    WHERE user_id = p_user_id
+      AND overage_credits > 0
+    RETURNING overage_credits INTO new_overage;
+
+    IF NOT FOUND THEN
+      RETURN jsonb_build_object(
+        'allowed', false,
+        'reservation_id', NULL,
+        'status', 'denied',
+        'current', current_count,
+        'limit', p_base_limit,
+        'period', p_period,
+        'tier', subscription_tier,
+        'overage_credits', 0,
+        'consumed_from', 'none'
+      );
+    END IF;
+
+    overage := new_overage;
+    consumed_from := 'overage';
+  END IF;
+
+  INSERT INTO public.daily_usage(user_id, date, feature, count)
+  VALUES (p_user_id, CURRENT_DATE, p_feature, 1)
+  ON CONFLICT (user_id, date, feature)
+  DO UPDATE SET count = public.daily_usage.count + 1;
+
+  current_count := current_count + 1;
+  INSERT INTO public.llm_quota_reservations(
+    id, user_id, feature, consumed_from, tier, quota_period, quota_limit,
+    current_count, overage_after, lease_expires_at
+  ) VALUES (
+    p_reservation_id, p_user_id, p_feature, consumed_from, subscription_tier, p_period, p_base_limit,
+    current_count, overage, now() + interval '10 minutes'
+  );
+
+  RETURN jsonb_build_object(
+    'allowed', true,
+    'reservation_id', p_reservation_id,
+    'status', 'reserved',
+    'current', current_count,
+    'limit', p_base_limit,
+    'period', p_period,
+    'tier', subscription_tier,
+    'overage_credits', overage,
+    'consumed_from', consumed_from
+  );
+END;
+$$;
+
+CREATE OR REPLACE FUNCTION public.finalize_llm_quota(
+  p_reservation_id uuid,
+  p_succeeded boolean
+) RETURNS jsonb
+LANGUAGE plpgsql
+SECURITY DEFINER
+SET search_path = public, pg_temp
+AS $$
+DECLARE
+  reservation public.llm_quota_reservations%ROWTYPE;
+  final_status text;
+BEGIN
+  IF p_reservation_id IS NULL OR p_succeeded IS NULL THEN
+    RAISE EXCEPTION 'invalid_llm_quota_finalize' USING ERRCODE = '22023';
+  END IF;
+
+  SELECT * INTO reservation
+  FROM public.llm_quota_reservations
+  WHERE id = p_reservation_id;
+  IF NOT FOUND THEN
+    RAISE EXCEPTION 'llm_quota_reservation_not_found' USING ERRCODE = 'P0002';
+  END IF;
+
+  PERFORM pg_advisory_xact_lock(hashtextextended(reservation.user_id::text || ':' || reservation.feature, 20260928));
+  SELECT * INTO reservation
+  FROM public.llm_quota_reservations
+  WHERE id = p_reservation_id
+  FOR UPDATE;
+
+  IF reservation.status <> 'reserved' THEN
+    RETURN jsonb_build_object('reservation_id', reservation.id, 'status', reservation.status);
+  END IF;
+
+  IF p_succeeded THEN
+    final_status := 'completed';
+  ELSE
+    UPDATE public.daily_usage
+    SET count = greatest(count - 1, 0)
+    WHERE user_id = reservation.user_id
+      AND date = reservation.usage_date
+      AND feature = reservation.feature;
+
+    IF reservation.consumed_from = 'overage' THEN
+      UPDATE public.subscriptions
+      SET overage_credits = overage_credits + 1,
+          updated_at = now()
+      WHERE user_id = reservation.user_id;
+    END IF;
+    final_status := 'released';
+  END IF;
+
+  UPDATE public.llm_quota_reservations
+  SET status = final_status,
+      finalized_at = now(),
+      release_reason = CASE WHEN p_succeeded THEN NULL ELSE 'provider_failed' END
+  WHERE id = reservation.id;
+
+  RETURN jsonb_build_object('reservation_id', reservation.id, 'status', final_status);
+END;
+$$;
+
+REVOKE ALL ON FUNCTION public.reserve_llm_quota(uuid, uuid, text, integer, text) FROM PUBLIC, anon, authenticated;
+REVOKE ALL ON FUNCTION public.finalize_llm_quota(uuid, boolean) FROM PUBLIC, anon, authenticated;
+GRANT EXECUTE ON FUNCTION public.reserve_llm_quota(uuid, uuid, text, integer, text) TO service_role;
+GRANT EXECUTE ON FUNCTION public.finalize_llm_quota(uuid, boolean) TO service_role;
+
+COMMENT ON TABLE public.llm_quota_reservations IS
+  'Service-only leases that reserve LLM quota before the Anthropic call in llm-proxy and refund failed or expired generations.';