diff --git a/docs/shared-gpu-rollout.md b/docs/shared-gpu-rollout.md
new file mode 100644
index 0000000..5e529d5
--- /dev/null
+++ b/docs/shared-gpu-rollout.md
@@ -0,0 +1,20 @@
+# Shared GPU coordination rollout
+
+Both Coolify applications must use the same COMFY_CONTROL_URL (the 5080 host agent on port 8199), COMFY_CONTROL_TOKEN, and COMFY_HOST through its proxy on port 8198. The retired 192.168.77.101 sidecar is not involved.
+
+The agent now requires an opaque reservation for Comfy mutations and host start/stop/purge. Each application process creates a random ticket. No studio name, user identity, job name, prompt, or media is included in reservation requests. A waiting instance receives availability only. The host serializes acquisition, renews leases for active work, respects waiting tickets, and confirms the physical Comfy queue has drained before handing off an expired/released reservation.
+
+The HTTP proxy strips graphs and IDs from queue status and disables global history enumeration. Exact prompt history remains available for known job IDs. Automatic cleanup deletes named files only; global sweeps are disabled. This coordinates trusted instances sharing one GPU; it is not a separate-account security boundary around Comfy's local files or direct native port.
+
+Deployment order:
+
+1. Let active renders and output saves finish in both sites. Do not use Force reset from one site to clear the other.
+2. Update/restart the local host agent with all three adjacent files: comfy-host-agent.mjs, gpu-reservation.mjs, gpu-proxy.mjs. The launcher runs the files directly from this repository's scripts folder. Copying only comfy-host-agent.mjs is no longer sufficient.
+3. Deploy the same commit to AIGen and xAIGen. Updating the host before the sites temporarily blocks older clients; updating a site first leaves its jobs waiting until the new coordinator is available. There is deliberately no uncoordinated fallback.
+4. Verify both sites report available, then queue a render on one and a render on the other. The second should remain waiting with a generic availability message, then start after the first saves. Repeat with sites reversed and test that Force reset on the waiting site is rejected without clearing its jobs.
+
+Pushing to Gitea alone does not restart the Windows host-agent process. Coolify's website containers and the host agent are separate processes. Do not open direct Comfy port 8188 to either app as a workaround; both must submit via 8198 for fencing to apply.
+
+Recovery: clients renew every 10 seconds; host leases last 60 seconds. If a site disappears, its waiting ticket expires and its lease may be reassigned only after Comfy confirms idle. A lost connection never counts as an idle GPU. Known running prompt recovery remains in the original site. Global-history fallback recovery is intentionally unavailable because it could import the other site's results.
+
+Validation: node --test tests/studio-queue.test.mjs tests/gpu-reservation.test.mjs tests/shared-gpu.test.mjs. The HTTP integration test uses two independent application-client modules, the real reservation coordinator and proxy, and a simulated Comfy server. It does not start Comfy, render media, or alter library data.
diff --git a/pages/queue.vue b/pages/queue.vue
index 412bb56..91b78f4 100644
--- a/pages/queue.vue
+++ b/pages/queue.vue
@@ -81,6 +81,7 @@
                 <p class="mt-1 text-sm text-zinc-300">{{ jobLine(job) }}</p>
                 <p v-if="job.shots && liveMessage[job.shots.id]" class="mt-1 text-xs text-amber-100">{{ liveMessage[job.shots.id] }}</p>
                 <p v-else-if="liveMessage[job.id]" class="mt-1 text-xs text-amber-100">{{ liveMessage[job.id] }}</p>
+                <p v-if="job.status === 'waiting'" class="mt-1 text-xs text-zinc-400">{{ job.waitReason || 'In queue. Waiting for GPU availability.' }}</p>
                 <p v-if="job.lastError" class="mt-1 text-xs text-red-300">{{ job.lastError }}</p>
               </div>
             </button>
@@ -501,6 +502,7 @@ type Queue = {
   name: string
   status: string
   lastError?: string
+  waitReason?: string
   pendingCount: number
   completedCount: number
   totalCount: number
@@ -528,6 +530,7 @@ type StudioJobRow = {
   pauseAfterCurrent?: boolean
   pausedByUser?: boolean
   lastError?: string
+  waitReason?: string
   shots?: Queue | null
   plannedShots?: { prompt: string; duration: number; loraName?: string; loraStack?: LoraStackItem[] }[]
   completedCount?: number
@@ -556,6 +559,7 @@ type GenerationLogEntry = {
   prompt: string
   status: string
   lastError?: string
+  waitReason?: string
   payload: Record<string, any>
   imagePipeline?: string
 }
diff --git a/scripts/comfy-host-agent.mjs b/scripts/comfy-host-agent.mjs
index 02495ba..6bbfdc0 100644
--- a/scripts/comfy-host-agent.mjs
+++ b/scripts/comfy-host-agent.mjs
@@ -1,3 +1,5 @@
+import { createGpuReservation } from './gpu-reservation.mjs'
+import { createGpuProxy } from './gpu-proxy.mjs'
 import http from 'node:http'
 import net from 'node:net'
 import { execFile, spawn } from 'node:child_process'
@@ -141,26 +143,7 @@ let proxyTarget = 0
 
 function ensureProxyListening() {
   if (proxyServer) return
-  proxyServer = net.createServer((client) => {
-    const target = proxyTarget
-    if (!target) {
-      client.destroy()
-      return
-    }
-    const upstream = net.connect(target, '127.0.0.1')
-    const fail = () => {
-      try { client.destroy() } catch { /* ignore */ }
-      try { upstream.destroy() } catch { /* ignore */ }
-    }
-    client.on('error', fail)
-    upstream.on('error', fail)
-    client.once('data', (chunk) => {
-      if (isWorkHttp(chunk)) markWork()
-      upstream.write(chunk)
-      client.pipe(upstream)
-    })
-    upstream.pipe(client)
-  })
+  proxyServer = createGpuProxy({ target: () => proxyTarget, reservation: gpuReservation, authorized, markWork })
   proxyServer.on('error', (error) => {
     console.log(JSON.stringify({ src: 'comfy-host-agent', event: 'proxy-error', error: String(error.message || error) }))
   })
@@ -508,6 +491,7 @@ async function noteQueue(portNum) {
 }
 
 async function maybeIdleStop(healthyPort) {
+  if (gpuReservation.availability().busy) return
   if (healthyPort) {
     stoppedByAgent = false
     const queue = await noteQueue(healthyPort)
@@ -767,7 +751,7 @@ function readJson(req) {
 
 function purgeDesktopFiles(body) {
   const deleted = []
-  const allowSweep = body?.sweep !== false
+  const allowSweep = false // Never sweep another studio's files during a job cleanup.
   const names = [
     String(body?.imageName || body?.filename || ''),
     ...(Array.isArray(body?.imageNames) ? body.imageNames : [])
@@ -827,9 +811,30 @@ function purgeDesktopFiles(body) {
   return { ok: true, deleted: unique }
 }
 
-const server = http.createServer(async (req, res) => {
+const gpuReservation = createGpuReservation({ idle: async () => {
+  if ((await trainingLock()).busy) return false
+  const healthy = await syncProxy()
+  if (healthy) {
+    const queue = await fetchLocalQueue(healthy)
+    return queue.ok && queue.running === 0 && queue.pending === 0
+  }
+  // A stopped service may be reserved before waking; a silent live process may not.
+  return !(await processUp()) && !(await pythonMainUp().catch(() => true))
+} })
+
+async function handleControl(req, res) {
   if (!authorized(req)) return json(res, 401, { ok: false, error: 'unauthorized' })
   const url = new URL(req.url || '/', 'http://localhost')
+  if (req.method === 'POST' && url.pathname.startsWith('/gpu/')) {
+    const body = await readJson(req)
+    let result
+    if (url.pathname === '/gpu/acquire') result = await gpuReservation.acquire(body.ticket)
+    else if (url.pathname === '/gpu/renew') result = await gpuReservation.renew(body.token)
+    else if (url.pathname === '/gpu/release') result = await gpuReservation.release(body.token)
+    else if (url.pathname === '/gpu/cancel') result = await gpuReservation.cancel(body.ticket)
+    else return json(res, 404, { ok: false })
+    return json(res, 200, result)
+  }
   if (req.method === 'GET' && url.pathname === '/status') {
     // Answer immediately. MyMonitor allows ~500ms; probing ports + WMI here
     // made the A light stay red even while this process was running.
@@ -849,7 +854,8 @@ const server = http.createServer(async (req, res) => {
       idleMs,
       port: healthyPort || null,
       proxyPort,
-      training: lastTraining
+      gpu: gpuReservation.availability(),
+      training: { busy: lastTraining.busy }
     })
   }
   if (req.method === 'POST' && url.pathname === '/start') {
@@ -935,21 +941,21 @@ const server = http.createServer(async (req, res) => {
     const body = await readJson(req)
     return json(res, 200, purgeDesktopFiles(body))
   }
-  if (req.method === 'POST' && url.pathname === '/sweep') {
-    const body = await readJson(req)
-    const deleted = [
-      ...sweepStaleStudioInputs(body?.sweepMaxAgeMs),
-      ...sweepStaleStudioOutputs(body?.sweepPrefixes, body?.sweepSubfolders, body?.sweepMaxAgeMs)
-    ]
-    console.log(JSON.stringify({
-      src: 'comfy-host-agent',
-      event: 'sweep',
-      deleted: deleted.length,
-      files: deleted.map((path) => basename(path))
-    }))
-    return json(res, 200, { ok: true, deleted })
-  }
+  if (req.method === 'POST' && url.pathname === '/sweep') return json(res, 409, { ok: false, message: 'Global cleanup is disabled while studios share the GPU.' })
   json(res, 404, { ok: false, error: 'not found' })
+}
+
+const server = http.createServer(async (req, res) => {
+  if (!authorized(req)) return json(res, 401, { ok: false, error: 'unauthorized' })
+  try {
+    const path = new URL(req.url || '/', 'http://localhost').pathname
+    if (req.method === 'POST' && !path.startsWith('/gpu/')) {
+      await gpuReservation.permit(String(req.headers['x-aigen-gpu-lease'] || ''), () => handleControl(req, res))
+    } else await handleControl(req, res)
+  } catch (error) {
+    req.resume()
+    if (!res.headersSent) json(res, error.statusCode || 400, { ok: false, message: error.statusCode === 409 ? 'GPU is in use. Waiting for availability.' : 'GPU coordination request failed.' })
+  }
 })
 
 function logStartupSweep() {
diff --git a/scripts/gpu-proxy.mjs b/scripts/gpu-proxy.mjs
new file mode 100644
index 0000000..b03275c
--- /dev/null
+++ b/scripts/gpu-proxy.mjs
@@ -0,0 +1,81 @@
+import http from 'node:http'
+import net from 'node:net'
+import { GPU_WAIT_MESSAGE } from './gpu-reservation.mjs'
+
+function reply(res, status, body) {
+  if (res.headersSent) return res.destroy()
+  res.writeHead(status, { 'Content-Type': 'application/json', 'Cache-Control': 'no-store' })
+  res.end(JSON.stringify(body))
+}
+
+/** Streams Comfy HTTP/WebSocket traffic; all mutations require the current reservation. */
+export function createGpuProxy({ target, reservation, authorized = () => true, markWork = () => {} }) {
+  const server = http.createServer(async (req, res) => {
+    const path = new URL(req.url || '/', 'http://localhost').pathname.replace(/\/+$/, '') || '/'
+    // A global history list can expose another studio's prompts and outputs.
+    if (req.method === 'GET' && (path === '/history' || path === '/history/')) return reply(res, 200, {})
+    const forward = () => new Promise(resolve => {
+      const port = target()
+      if (!port) { reply(res, 503, { error: 'GPU service is unavailable.' }); return resolve() }
+      const headers = { ...req.headers }
+      delete headers['x-aigen-gpu-lease']
+      delete headers.authorization
+      const upstream = http.request({ hostname: '127.0.0.1', port, path: req.url, method: req.method, headers }, response => {
+        if (req.method === 'GET' && path === '/queue') {
+          let size = 0
+          const chunks = []
+          response.on('data', chunk => {
+            size += chunk.length
+            if (size > 16 * 1024 * 1024) { response.destroy(); reply(res, 502, { error: 'GPU status unavailable.' }); resolve(); return }
+            chunks.push(chunk)
+          })
+          response.on('end', () => {
+            try {
+              if (response.statusCode !== 200) throw new Error('status unavailable')
+              const queue = JSON.parse(Buffer.concat(chunks).toString('utf8'))
+              if (!Array.isArray(queue.queue_running) || !Array.isArray(queue.queue_pending)) throw new Error('invalid queue')
+              // Preserve count compatibility without revealing IDs, graphs, or prompts.
+              reply(res, 200, { queue_running: queue.queue_running.map(() => null), queue_pending: queue.queue_pending.map(() => null) })
+            } catch { reply(res, 502, { error: 'GPU status unavailable.' }) }
+            resolve()
+          })
+        } else {
+          res.writeHead(response.statusCode || 502, response.headers)
+          response.pipe(res)
+          response.on('end', resolve)
+        }
+        response.on('error', () => { res.destroy(); resolve() })
+      })
+      upstream.on('error', () => { reply(res, 502, { error: 'GPU service is unavailable.' }); resolve() })
+      upstream.setTimeout(5 * 60 * 1000, () => upstream.destroy())
+      req.on('aborted', () => upstream.destroy())
+      res.on('close', () => { upstream.destroy(); resolve() })
+      req.pipe(upstream)
+    })
+    try {
+      if (req.method === 'GET' || req.method === 'HEAD') await forward()
+      else {
+        if (!authorized(req)) { req.resume(); return reply(res, 401, { error: 'Unauthorized' }) }
+        await reservation.permit(String(req.headers['x-aigen-gpu-lease'] || ''), async () => { markWork(); await forward() })
+      }
+    } catch {
+      req.resume()
+      reply(res, 409, { error: { message: GPU_WAIT_MESSAGE }, code: 'GPU_BUSY' })
+    }
+  })
+  server.on('upgrade', (req, socket, head) => {
+    if (new URL(req.url || '/', 'http://localhost').pathname !== '/ws' || !target()) return socket.destroy()
+    const upstream = net.connect(target(), '127.0.0.1', () => {
+      const headers = Object.entries(req.headers).filter(([key]) => key !== 'authorization' && key !== 'x-aigen-gpu-lease')
+        .map(([key, value]) => `${key}: ${value}`).join('\r\n')
+      upstream.write(`${req.method} ${req.url} HTTP/${req.httpVersion}\r\n${headers}\r\n\r\n`)
+      if (head.length) upstream.write(head)
+      socket.pipe(upstream); upstream.pipe(socket)
+    })
+    socket.on('error', () => upstream.destroy())
+    upstream.on('error', () => socket.destroy())
+    socket.on('close', () => upstream.destroy())
+    upstream.on('close', () => socket.destroy())
+  })
+  return server
+}
diff --git a/scripts/gpu-reservation.mjs b/scripts/gpu-reservation.mjs
new file mode 100644
index 0000000..07cb497
--- /dev/null
+++ b/scripts/gpu-reservation.mjs
@@ -0,0 +1,68 @@
+import { randomUUID } from 'node:crypto'
+
+export const GPU_WAIT_MESSAGE = 'GPU is in use. Waiting for availability.'
+
+/** Device-local arbitration. Tickets/tokens are opaque; no studio or job metadata is stored. */
+export function createGpuReservation({ idle, now = Date.now, ttlMs = 60_000, ticketTtlMs = 30_000 } = {}) {
+  if (typeof idle !== 'function') throw new Error('An authoritative GPU idle probe is required')
+  let owner = null
+  let gate = Promise.resolve()
+  let inFlight = 0
+  const waiting = new Map()
+  const serialize = fn => {
+    const run = gate.then(fn)
+    gate = run.catch(() => {})
+    return run
+  }
+  const valid = token => Boolean(owner && !owner.released && owner.token === token && owner.until > now())
+  const busy = () => ({ acquired: false, message: GPU_WAIT_MESSAGE, retryAfterMs: 2500 })
+  const prune = () => {
+    for (const [ticket, seen] of waiting) if (now() - seen >= ticketTtlMs) waiting.delete(ticket)
+  }
+  return {
+    acquire(ticket) {
+      return serialize(async () => {
+        if (typeof ticket !== 'string' || !/^[a-zA-Z0-9-]{16,80}$/.test(ticket)) throw new Error('Invalid reservation ticket')
+        prune()
+        if (owner?.ticket === ticket && valid(owner.token)) {
+          owner.until = now() + ttlMs
+          return { acquired: true, token: owner.token, ttlMs }
+        }
+        waiting.set(ticket, now())
+        if (owner && (valid(owner.token) || inFlight > 0)) return busy()
+        if (waiting.keys().next().value !== ticket) return busy()
+        // Unknown/offline is not idle; the adapter must explicitly account for a stopped GPU.
+        if (await idle() !== true) return busy()
+        owner = { ticket, token: randomUUID(), until: now() + ttlMs, released: false }
+        waiting.delete(ticket)
+        return { acquired: true, token: owner.token, ttlMs }
+      })
+    },
+    renew(token) {
+      return serialize(() => {
+        if (!valid(token)) return { renewed: false }
+        owner.until = now() + ttlMs
+        return { renewed: true, ttlMs }
+      })
+    },
+    release(token) {
+      return serialize(() => {
+        if (!owner || owner.token !== token) return { released: false }
+        owner.released = true
+        // The next acquire still verifies that Comfy has drained before granting access.
+        return { released: true }
+      })
+    },
+    cancel(ticket) { return serialize(() => { waiting.delete(ticket); return { cancelled: true } }) },
+    async permit(token, operation) {
+      const accepted = await serialize(() => {
+        if (!valid(token)) return false
+        inFlight += 1
+        return true
+      })
+      if (!accepted) throw Object.assign(new Error(GPU_WAIT_MESSAGE), { statusCode: 409 })
+      try { return await operation() } finally { inFlight -= 1 }
+    },
+    availability() { return { busy: Boolean(owner && (valid(owner.token) || inFlight > 0)) } }
+  }
+}
diff --git a/server/api/comfy/force-reset.post.ts b/server/api/comfy/force-reset.post.ts
index 5c0c828..e29aac5 100644
--- a/server/api/comfy/force-reset.post.ts
+++ b/server/api/comfy/force-reset.post.ts
@@ -1,15 +1,18 @@
+import { withSharedGpuReset } from '~/server/utils/sharedGpu'
 import { libraryOwnerKey } from '~/server/utils/library'
 import { requestComfyForceReset } from '~/server/utils/comfyLifecycle'
 import { clearStuckStudioWork } from '~/server/utils/studioQueue'
 
 export default defineEventHandler(async (event) => {
   const owner = libraryOwnerKey(event)
-  const cleared = await clearStuckStudioWork(owner)
-  const comfy = await requestComfyForceReset()
-  return {
-    ok: true,
-    message: 'Cleared every stuck Studio/music/shot job and force-stopped Comfy. Use Wake / Poke when you want the GPU again.',
-    cleared,
-    comfy
-  }
+  return withSharedGpuReset(async () => {
+    const cleared = await clearStuckStudioWork(owner)
+    const comfy = await requestComfyForceReset()
+    return {
+      ok: true,
+      message: 'Cleared every stuck Studio/music/shot job and force-stopped Comfy. Use Wake / Poke when you want the GPU again.',
+      cleared,
+      comfy
+    }
+  })
 })
diff --git a/server/plugins/shared-gpu.ts b/server/plugins/shared-gpu.ts
new file mode 100644
index 0000000..4f7d6e8
--- /dev/null
+++ b/server/plugins/shared-gpu.ts
@@ -0,0 +1,17 @@
+import { hasActivePromptJobs } from '~/server/utils/promptComfy'
+import { listJobs } from '~/server/utils/jobs'
+import { registerSharedGpuWork, maintainSharedGpu } from '~/server/utils/sharedGpu'
+
+export default defineNitroPlugin((nitro) => {
+  registerSharedGpuWork(() => hasActivePromptJobs() || listJobs().some(job =>
+    job.saving || job.library?.chainContinuing || ['queued', 'uploading', 'running'].includes(job.status)
+  ))
+  let running = false
+  const timer = setInterval(async () => {
+    if (running) return
+    running = true
+    try { await maintainSharedGpu() } finally { running = false }
+  }, 10_000)
+  timer.unref()
+  nitro.hooks.hook('close', () => { clearInterval(timer) })
+})
diff --git a/server/utils/comfy.ts b/server/utils/comfy.ts
index f66f6f0..93c9488 100644
--- a/server/utils/comfy.ts
+++ b/server/utils/comfy.ts
@@ -1,3 +1,4 @@
+import { assertSharedGpu, sharedGpuHeaders } from '~/server/utils/sharedGpu'
 import { LTX_NEGATIVE } from '~/utils/videoModels'
 import { createHash } from 'node:crypto'
 import { comfyJobPrefix } from '~/utils/outputNames'
@@ -73,6 +74,9 @@ function configuredComfyBase() {
 }
 
 export function getComfyHost() {
+  // Shared studios must never bypass the reservation-enforcing proxy.
+  const sharedHost = agentFrontDoorOrigin()
+  if (sharedHost) return sharedHost
   if (comfyHostOverride) return viaAgentFrontDoor(comfyHostOverride) || comfyHostOverride
   return viaAgentFrontDoor(configuredComfyBase()) || configuredComfyBase()
 }
@@ -83,6 +87,12 @@ export function comfyWsUrl(clientId: string) {
 
 export async function comfyFetch(path: string, init?: RequestInit) {
   const url = `${getComfyHost()}${path}`
+  if (init?.method && !['GET', 'HEAD'].includes(init.method.toUpperCase())) {
+    await assertSharedGpu()
+    const headers = new Headers(init.headers)
+    for (const [key, value] of Object.entries(sharedGpuHeaders())) headers.set(key, value)
+    init = { ...init, headers }
+  }
   try {
     return await fetch(url, init)
   } catch (error) {
@@ -623,7 +633,8 @@ async function purgeOnDesktop(opts: {
       headers: {
         'Content-Type': 'application/json',
         Accept: 'application/json',
-        ...(token ? { Authorization: `Bearer ${token}` } : {})
+        ...(token ? { Authorization: `Bearer ${token}` } : {}),
+        ...sharedGpuHeaders()
       },
       body: JSON.stringify({
         imageName: imageNames[0] || '',
diff --git a/server/utils/comfyLifecycle.ts b/server/utils/comfyLifecycle.ts
index 147b366..260b47e 100644
--- a/server/utils/comfyLifecycle.ts
+++ b/server/utils/comfyLifecycle.ts
@@ -1,3 +1,4 @@
+import { assertSharedGpu, sharedGpuHeaders, withSharedGpuStart } from '~/server/utils/sharedGpu'
 import { execFile, spawn } from 'node:child_process'
 import { promisify } from 'node:util'
 import { getComfyHost, setComfyHostOverride, comfyConfigured } from '~/server/utils/comfy'
@@ -85,13 +86,15 @@ export async function fetchQueue() {
 async function controlRequest(path: string, method = 'GET', timeoutMs = 5000, body?: Record<string, unknown>) {
   const { controlUrl, controlToken } = settings()
   if (!controlUrl) return null
+  if (method !== 'GET') await assertSharedGpu()
   try {
     const res = await fetch(`${controlUrl}${path}`, {
       method,
       headers: {
         Accept: 'application/json',
         ...(body ? { 'Content-Type': 'application/json' } : {}),
-        ...(controlToken ? { Authorization: `Bearer ${controlToken}` } : {})
+        ...(controlToken ? { Authorization: `Bearer ${controlToken}` } : {}),
+        ...(method !== 'GET' ? sharedGpuHeaders() : {})
       },
       ...(body ? { body: JSON.stringify(body) } : {}),
       signal: AbortSignal.timeout(timeoutMs)
@@ -344,7 +347,7 @@ async function waitWhileBusy(onStatus: StatusFn) {
   const started = Date.now()
   while (Date.now() - started < busyWaitMs) {
     const queue = await fetchQueue()
-    if (queue.running === 0) return
+    if (queue.ok && queue.running === 0 && queue.pending === 0) return
     onStatus({
       state: 'busy',
       message: `ComfyUI is busy with another prompt (${queue.running} running, ${queue.pending} queued). Waiting up to 3 minutes, then this job will be saved.`,
@@ -488,7 +491,10 @@ async function ensureUnlocked(onStatus: StatusFn, skipBusyWait = false) {
 
 export function ensureComfyReady(onStatus: StatusFn = () => undefined, options?: { skipBusyWait?: boolean }) {
   const skipBusyWait = options?.skipBusyWait === true
-  const run = gate.then(() => ensureUnlocked(onStatus, skipBusyWait))
+  const run = gate.then(() => withSharedGpuStart(
+    () => ensureUnlocked(onStatus, skipBusyWait),
+    async () => { await assertSharedGpu() }
+  ))
   gate = run.then(() => undefined, () => undefined)
   return run
 }
diff --git a/server/utils/imageComfy.ts b/server/utils/imageComfy.ts
index a194aef..2218321 100644
--- a/server/utils/imageComfy.ts
+++ b/server/utils/imageComfy.ts
@@ -1,3 +1,4 @@
+import { assertSharedGpu, sharedGpuHeaders, sharedGpuConfigured } from '~/server/utils/sharedGpu'
 import { createHash } from 'node:crypto'
 import { AsyncLocalStorage } from 'node:async_hooks'
 import { getComfyHost, viaAgentFrontDoor } from '~/server/utils/comfy'
@@ -61,6 +62,7 @@ export function getSidecarImageHost() {
 }
 
 export function getImageComfyHost() {
+  if (sharedGpuConfigured()) return getComfyHost()
   const fromAls = imageHostAls.getStore()
   if (fromAls) return viaAgentFrontDoor(fromAls) || fromAls
   if (imageComfyHostOverride) return viaAgentFrontDoor(imageComfyHostOverride) || imageComfyHostOverride
@@ -80,6 +82,12 @@ export async function imageComfyFetch(path: string, init?: RequestInit) {
   if (!host) {
     throw createError({ statusCode: 500, statusMessage: 'No image ComfyUI host is configured' })
   }
+  if (init?.method && !['GET', 'HEAD'].includes(init.method.toUpperCase())) {
+    await assertSharedGpu()
+    const headers = new Headers(init.headers)
+    for (const [key, value] of Object.entries(sharedGpuHeaders())) headers.set(key, value)
+    init = { ...init, headers }
+  }
   try {
     return await fetch(`${host}${path}`, init)
   } catch (error) {
@@ -390,7 +398,8 @@ async function purgeImageOnDesktop(opts: {
       headers: {
         'Content-Type': 'application/json',
         Accept: 'application/json',
-        ...(token ? { Authorization: `Bearer ${token}` } : {})
+        ...(token ? { Authorization: `Bearer ${token}` } : {}),
+        ...sharedGpuHeaders()
       },
       body: JSON.stringify({
         imageName: imageNames[0] || '',
diff --git a/server/utils/imageComfyLifecycle.ts b/server/utils/imageComfyLifecycle.ts
index 46dc6f8..25a6e29 100644
--- a/server/utils/imageComfyLifecycle.ts
+++ b/server/utils/imageComfyLifecycle.ts
@@ -1,3 +1,4 @@
+import { assertSharedGpu, sharedGpuHeaders, withSharedGpuStart } from '~/server/utils/sharedGpu'
 import { getImageComfyHost, setImageComfyHostOverride, imageComfyConfigured, getBeastImageHost, getSidecarImageHost, withImageComfyHost, type ImageEditBox } from '~/server/utils/imageComfy'
 
 export type ImageComfyState = 'online' | 'booting' | 'busy' | 'starting' | 'offline'
@@ -92,12 +93,14 @@ export async function fetchImageQueue() {
 async function controlRequest(path: string, method = 'GET', timeoutMs = 5000) {
   const { controlUrl, controlToken } = settings()
   if (!controlUrl) return null
+  if (method !== 'GET') await assertSharedGpu()
   try {
     const res = await fetch(`${controlUrl}${path}`, {
       method,
       headers: {
         Accept: 'application/json',
-        ...(controlToken ? { Authorization: `Bearer ${controlToken}` } : {})
+        ...(controlToken ? { Authorization: `Bearer ${controlToken}` } : {}),
+        ...(method !== 'GET' ? sharedGpuHeaders() : {})
       },
       signal: AbortSignal.timeout(timeoutMs)
     })
@@ -238,7 +241,7 @@ async function ensureUnlocked(onStatus: StatusFn) {
 }
 
 export function ensureImageComfyReady(onStatus: StatusFn = () => undefined) {
-  const run = gate.then(() => ensureUnlocked(onStatus))
+  const run = gate.then(() => withSharedGpuStart(() => ensureUnlocked(onStatus), async () => { await assertSharedGpu() }))
   gate = run.then(() => undefined, () => undefined)
   return run
 }
diff --git a/server/utils/promptComfy.ts b/server/utils/promptComfy.ts
index ba8a4da..fddc52d 100644
--- a/server/utils/promptComfy.ts
+++ b/server/utils/promptComfy.ts
@@ -1,4 +1,5 @@
-import { comfyInputFilename } from '~/server/utils/comfy'
+import { assertSharedGpu, sharedGpuHeaders, sharedGpuConfigured } from '~/server/utils/sharedGpu'
+import { comfyInputFilename, getComfyHost } from '~/server/utils/comfy'
 import { getSidecarImageHost } from '~/server/utils/imageComfy'
 import { ensureSidecarReady } from '~/server/utils/imageComfyLifecycle'
 import { buildVisionPromptWorkflow } from '~/server/utils/promptWorkflow'
@@ -19,6 +20,7 @@ const jobs = new Map<string, PromptJob>()
 const MAX_JOBS = 20
 
 export function getPromptComfyHost() {
+  if (sharedGpuConfigured()) return getComfyHost()
   return getSidecarImageHost()
 }
 
@@ -31,6 +33,12 @@ async function promptComfyFetch(path: string, init?: RequestInit) {
   if (!host) {
     throw createError({ statusCode: 503, statusMessage: 'Qwen VL is not configured. Set COMFY_HOST or IMAGE_COMFY_HOST to Beast.' })
   }
+  if (init?.method && !['GET', 'HEAD'].includes(init.method.toUpperCase())) {
+    await assertSharedGpu()
+    const headers = new Headers(init.headers)
+    for (const [key, value] of Object.entries(sharedGpuHeaders())) headers.set(key, value)
+    init = { ...init, headers }
+  }
   try {
     return await fetch(`${host}${path}`, init)
   } catch (error) {
@@ -260,3 +268,7 @@ export function failPromptJob(job: PromptJob, error: unknown) {
   job.error = err.statusMessage || err.message || 'Prompt recommend failed'
   job.message = job.error
 }
+
+export function hasActivePromptJobs() {
+  return [...jobs.values()].some(job => job.status === 'queued' || job.status === 'running')
+}
diff --git a/server/utils/sharedGpu.ts b/server/utils/sharedGpu.ts
new file mode 100644
index 0000000..8028eae
--- /dev/null
+++ b/server/utils/sharedGpu.ts
@@ -0,0 +1,106 @@
+import { randomUUID } from 'node:crypto'
+
+const ticket = randomUUID()
+let lease = ''
+let expiresAt = 0
+let lost = false
+let starting = 0
+let resetting = false
+let gate: Promise<unknown> = Promise.resolve()
+let localWork: () => boolean = () => true
+let reason = 'GPU is in use. Waiting for availability.'
+
+function settings() {
+  const config = useRuntimeConfig()
+  return {
+    url: String(config.comfyControlUrl || process.env.COMFY_CONTROL_URL || '').replace(/\/$/, ''),
+    token: String(config.comfyControlToken || process.env.COMFY_CONTROL_TOKEN || '')
+  }
+}
+export function sharedGpuConfigured() { return Boolean(settings().url) }
+export function sharedGpuWaitReason() { return reason }
+export function registerSharedGpuWork(check: () => boolean) { localWork = check }
+
+async function request(path: string, body: Record<string, string>) {
+  const { url, token } = settings()
+  const response = await fetch(`${url}/gpu/${path}`, {
+    method: 'POST', headers: { 'Content-Type': 'application/json', ...(token ? { Authorization: `Bearer ${token}` } : {}) },
+    body: JSON.stringify(body), signal: AbortSignal.timeout(15_000)
+  })
+  if (!response.ok) throw new Error('GPU coordinator unavailable')
+  return await response.json() as { acquired?: boolean; token?: string; ttlMs?: number; renewed?: boolean; released?: boolean }
+}
+function serialized<T>(fn: () => Promise<T>): Promise<T> {
+  const run = gate.then(fn)
+  gate = run.catch(() => {})
+  return run
+}
+
+export function acquireSharedGpu() {
+  return serialized(async () => {
+    if (!sharedGpuConfigured()) return true
+    if (lost) return false
+    if (lease && Date.now() < expiresAt) return true
+    if (lease) { lost = true; return false }
+    try {
+      const result = await request('acquire', { ticket })
+      if (!result.acquired || !result.token || !Number.isFinite(result.ttlMs) || Number(result.ttlMs) < 10_000) {
+        reason = 'GPU is in use. Waiting for availability.'
+        return false
+      }
+      lease = result.token
+      expiresAt = Date.now() + Math.max(1000, Number(result.ttlMs) - 5000)
+      return true
+    } catch {
+      reason = 'GPU coordinator unavailable. Waiting to reconnect.'
+      return false
+    }
+  })
+}
+
+export async function withSharedGpuStart<T>(fn: () => Promise<T>, blocked: () => Promise<T>): Promise<T> {
+  starting += 1
+  try { return await (!resetting && await acquireSharedGpu() ? fn() : blocked()) }
+  finally { starting -= 1 }
+}
+
+export async function assertSharedGpu() {
+  if (!await acquireSharedGpu()) throw createError({ statusCode: 409, statusMessage: reason, data: { code: 'GPU_BUSY' } })
+}
+
+export function sharedGpuHeaders() {
+  if (!sharedGpuConfigured()) return {} as Record<string, string>
+  if (!lease || lost || Date.now() >= expiresAt) {
+    throw createError({ statusCode: 409, statusMessage: 'GPU reservation is unavailable. Waiting to reconnect.', data: { code: 'GPU_BUSY' } })
+  }
+  const { token } = settings()
+  return { 'x-aigen-gpu-lease': lease, ...(token ? { Authorization: `Bearer ${token}` } : {}) }
+}
+
+export function maintainSharedGpu() {
+  return serialized(async () => {
+    if (!sharedGpuConfigured()) return
+    if (!starting && !resetting && !localWork()) {
+      if (lease) {
+        try { await request('release', { token: lease }) } catch { /* expires if the host is unreachable */ }
+      }
+      lease = ''; expiresAt = 0; lost = false
+      return
+    }
+    if (!lease || lost) return
+    try {
+      const result = await request('renew', { token: lease })
+      if (!result.renewed || !Number.isFinite(result.ttlMs) || Number(result.ttlMs) < 10_000) { lost = true; return }
+      expiresAt = Date.now() + Math.max(1000, Number(result.ttlMs) - 5000)
+    } catch {
+      if (Date.now() >= expiresAt) lost = true
+    }
+  })
+}
+
+export async function withSharedGpuReset<T>(fn: () => Promise<T>) {
+  if (resetting) throw createError({ statusCode: 409, statusMessage: 'GPU reset is already in progress.' })
+  resetting = true
+  try { await assertSharedGpu(); return await fn() }
+  finally { resetting = false }
+}
diff --git a/server/utils/studioQueue.ts b/server/utils/studioQueue.ts
index 059e13f..f50d82f 100644
--- a/server/utils/studioQueue.ts
+++ b/server/utils/studioQueue.ts
@@ -1,3 +1,4 @@
+import { withSharedGpuStart, sharedGpuWaitReason, maintainSharedGpu, acquireSharedGpu } from '~/server/utils/sharedGpu'
 import { existsSync, mkdirSync, readdirSync, readFileSync, renameSync, writeFileSync } from 'node:fs'
 import { join } from 'node:path'
 import { getJob, listJobs, emitJob, type Job } from '~/server/utils/jobs'
@@ -98,6 +99,7 @@ export interface StudioJob {
   pausedByUser?: boolean
   resumeAutoRun?: boolean
   lastError?: string
+  waitReason?: string
 }
 
 type StudioQueueStore = {
@@ -246,7 +248,8 @@ export function summarizeStudioJob(job: StudioJob) {
     holdForCutIn: job.holdForCutIn === true,
     pauseAfterCurrent: job.pauseAfterCurrent === true,
     pausedByUser: job.pausedByUser === true,
-    lastError: job.lastError
+    lastError: job.lastError,
+    waitReason: job.status === 'waiting' ? job.waitReason : undefined
   }
 }
 
@@ -415,14 +418,11 @@ export async function videoJobsBusy() {
   }))) return true
   const queue = await fetchLiveQueue()
   if (queue) {
-    if (queue.running > 0) return true
-    if (queue.pending > 0) {
-      if (listJobs().some(job => liveJobOwnsGpu(job) || jobIsLocallySubmitting(job))) return true
-      if (listPendingJobs().some((pending) => {
-        if (!pending.promptId || pending.stopAfterCurrent) return false
-        return Date.now() - pending.startedAt < PENDING_ORPHAN_MS
-      })) return true
-      return false
+    if (queue.running > 0 || queue.pending > 0) {
+      // Join the device queue while another instance is rendering, so it cannot
+      // reclaim every gap ahead of this waiting instance.
+      await acquireSharedGpu()
+      return true
     }
     return false
   }
@@ -865,7 +865,7 @@ function pendingAlive(job: StudioJob) {
 }
 
 function isTransientComfyError(error?: string) {
-  return /still busy|COMFY_BUSY|offline|never answered|host agent|unreachable|asleep|Starting Comfy|ComfyUI \(1\)|instance picker|refused to start|API never answered|cold start|ECONNREFUSED|ETIMEDOUT|fetch failed|502|503/i.test(String(error || ''))
+  return /GPU is in use|GPU reservation|GPU coordinator|GPU_BUSY|still busy|COMFY_BUSY|offline|never answered|host agent|unreachable|asleep|Starting Comfy|ComfyUI \(1\)|instance picker|refused to start|API never answered|cold start|ECONNREFUSED|ETIMEDOUT|fetch failed|502|503/i.test(String(error || ''))
 }
 
 async function parkStudioOnStartFailure(owner: string, id: string, message: string) {
@@ -1010,11 +1010,12 @@ async function dispatchStudioQueue() {
   }
   await settleAttachedTerminalLives()
   if (await videoJobsBusy()) {
-    if (owners.some(owner => readJobs(owner).some(job => job.status === 'waiting'))) {
+    if (owners.some(owner => readJobs(owner).some(job => job.status === 'waiting' || (job.status === 'held' && !job.pausedByUser)))) {
       scheduleKickRetry()
     }
     return
   }
+  await maintainSharedGpu()
   // Re-read after videoJobsBusy — reap/settle may have rewritten disk rows.
   for (const owner of owners) {
     const store = readStore(owner)
@@ -1039,6 +1040,13 @@ async function dispatchStudioQueue() {
 }
 
 async function resumeHeldStudioJob(item: StudioJob) {
+  return withSharedGpuStart(() => resumeHeldStudioJobReserved(item), async () => {
+    scheduleKickRetry()
+    return false
+  })
+}
+
+async function resumeHeldStudioJobReserved(item: StudioJob) {
   const latest = readJobs(item.ownerKey).find(job => job.id === item.id)
   if (!latest || latest.status === 'cancelled') return false
   if (!latest.shotQueueId) {
@@ -1386,6 +1394,13 @@ async function startStudioMusicJob(item: StudioJob) {
 }
 
 export async function startStudioJob(item: StudioJob) {
+  return withSharedGpuStart(() => startStudioJobReserved(item), async () => {
+    await patchStudioJob(item.ownerKey, item.id, row => { row.waitReason = sharedGpuWaitReason() })
+    scheduleKickRetry()
+  })
+}
+
+async function startStudioJobReserved(item: StudioJob) {
   if (studioJobKind(item) === 'music') {
     await startStudioMusicJob(item)
     return
diff --git a/tests/gpu-reservation.test.mjs b/tests/gpu-reservation.test.mjs
new file mode 100644
index 0000000..9dd19ab
--- /dev/null
+++ b/tests/gpu-reservation.test.mjs
@@ -0,0 +1,75 @@
+import test from 'node:test'
+import assert from 'node:assert/strict'
+import { createGpuReservation, GPU_WAIT_MESSAGE } from '../scripts/gpu-reservation.mjs'
+const a = 'aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa'
+const b = 'bbbbbbbb-bbbb-bbbb-bbbb-bbbbbbbbbbbb'
+
+test('simultaneous sites receive exactly one reservation', async () => {
+  const gpu = createGpuReservation({ idle: async () => true })
+  const replies = await Promise.all([gpu.acquire(a), gpu.acquire(b)])
+  assert.equal(replies.filter(reply => reply.acquired).length, 1)
+  assert.deepEqual(replies[1], { acquired: false, message: GPU_WAIT_MESSAGE, retryAfterMs: 2500 })
+  assert.deepEqual(gpu.availability(), { busy: true })
+})
+test('another site cannot renew, release, or execute with an invalid token', async () => {
+  const gpu = createGpuReservation({ idle: async () => true })
+  const first = await gpu.acquire(a)
+  assert.deepEqual(await gpu.renew(b), { renewed: false })
+  assert.deepEqual(await gpu.release(b), { released: false })
+  await assert.rejects(gpu.permit(b, () => assert.fail('must not execute')), { statusCode: 409 })
+  assert.equal((await gpu.acquire(b)).acquired, false)
+  assert.equal(await gpu.permit(first.token, () => 'allowed'), 'allowed')
+})
+test('release never grants another site while Comfy still has work', async () => {
+  let idle = true
+  const gpu = createGpuReservation({ idle: async () => idle })
+  const first = await gpu.acquire(a)
+  idle = false
+  await gpu.release(first.token)
+  assert.equal((await gpu.acquire(b)).acquired, false)
+  idle = true
+  assert.equal((await gpu.acquire(b)).acquired, true)
+  await assert.rejects(gpu.permit(first.token, () => {}), { statusCode: 409 })
+})
+test('expired reservations recover only after confirmed GPU idle', async () => {
+  let time = 0, idle = true
+  const gpu = createGpuReservation({ idle: async () => idle, now: () => time, ttlMs: 100 })
+  const first = await gpu.acquire(a)
+  time = 101; idle = false
+  assert.equal((await gpu.acquire(b)).acquired, false)
+  assert.equal((await gpu.renew(first.token)).renewed, false)
+  idle = true
+  assert.equal((await gpu.acquire(b)).acquired, true)
+})
+test('an unanswered idle probe fails closed', async () => {
+  const gpu = createGpuReservation({ idle: async () => null })
+  assert.equal((await gpu.acquire(a)).acquired, false)
+})
+test('a waiting site gets the next reservation before the previous owner can reacquire', async () => {
+  const gpu = createGpuReservation({ idle: async () => true })
+  const first = await gpu.acquire(a)
+  await gpu.acquire(b)
+  await gpu.release(first.token)
+  assert.equal((await gpu.acquire(a)).acquired, false)
+  assert.equal((await gpu.acquire(b)).acquired, true)
+})
+test('an expired reservation cannot transfer while submission is in flight', async () => {
+  let time = 0, finish
+  const gpu = createGpuReservation({ idle: async () => true, now: () => time, ttlMs: 100 })
+  const first = await gpu.acquire(a)
+  const work = gpu.permit(first.token, () => new Promise(resolve => { finish = resolve }))
+  await new Promise(resolve => setImmediate(resolve))
+  time = 101
+  assert.equal((await gpu.acquire(b)).acquired, false)
+  finish(); await work
+  assert.equal((await gpu.acquire(b)).acquired, true)
+})
+test('disconnected waiters expire so they cannot block the device forever', async () => {
+  let time = 0
+  const gpu = createGpuReservation({ idle: async () => true, now: () => time, ttlMs: 100, ticketTtlMs: 50 })
+  const first = await gpu.acquire(a)
+  await gpu.acquire(b)
+  time = 51
+  await gpu.release(first.token)
+  assert.equal((await gpu.acquire(a)).acquired, true)
+})
diff --git a/tests/shared-gpu.test.mjs b/tests/shared-gpu.test.mjs
new file mode 100644
index 0000000..f2e7904
--- /dev/null
+++ b/tests/shared-gpu.test.mjs
@@ -0,0 +1,81 @@
+import test from 'node:test'
+import assert from 'node:assert/strict'
+import http from 'node:http'
+import { createRequire } from 'node:module'
+import { readFileSync } from 'node:fs'
+import ts from 'typescript'
+import { createGpuReservation } from '../scripts/gpu-reservation.mjs'
+import { createGpuProxy } from '../scripts/gpu-proxy.mjs'
+const require = createRequire(import.meta.url)
+const compiled = ts.transpileModule(readFileSync(new URL('../server/utils/sharedGpu.ts', import.meta.url), 'utf8'), {
+  compilerOptions: { module: ts.ModuleKind.CommonJS, target: ts.ScriptTarget.ES2022 }
+}).outputText
+const listen = server => new Promise(resolve => server.listen(0, '127.0.0.1', () => resolve(server.address().port)))
+const close = server => new Promise(resolve => { server.closeAllConnections(); server.close(resolve) })
+const json = (res, body) => { res.setHeader('Content-Type', 'application/json'); res.end(JSON.stringify(body)) }
+function client(url) {
+  const exports = {}
+  new Function('require', 'exports', 'useRuntimeConfig', 'createError', compiled)(require, exports,
+    () => ({ comfyControlUrl: url, comfyControlToken: 'test-secret' }),
+    info => Object.assign(new Error(info.statusMessage), info))
+  let active = false
+  exports.registerSharedGpuWork(() => active)
+  return { api: exports, active: value => { active = value } }
+}
+
+test('two independent studio clients share the real HTTP gateway without sharing job details', async t => {
+  let busy = false
+  const mutations = []
+  const comfy = http.createServer((req,res) => {
+    if (req.method === 'GET') return json(res, { queue_running: busy ? [[1, 'private-id', { prompt: 'private prompt from other site' }]] : [], queue_pending: [] })
+    mutations.push(req.url)
+    req.resume(); req.on('end', () => json(res, { prompt_id: 'opaque-result' }))
+  })
+  const comfyPort = await listen(comfy)
+  t.after(() => close(comfy))
+  const reservation = createGpuReservation({ idle: async () => !busy })
+  const control = http.createServer(async (req,res) => {
+    let text = ''; for await (const chunk of req) text += chunk
+    const body = JSON.parse(text || '{}')
+    assert.equal(req.headers.authorization, 'Bearer test-secret')
+    const op = req.url.split('/').at(-1)
+    json(res, await reservation[op](body.ticket || body.token))
+  })
+  const controlPort = await listen(control)
+  t.after(() => close(control))
+  const proxy = createGpuProxy({ target: () => comfyPort, reservation, authorized: req => req.headers.authorization === 'Bearer test-secret' })
+  const proxyPort = await listen(proxy)
+  t.after(() => close(proxy))
+  const a = client(`http://127.0.0.1:${controlPort}`)
+  const b = client(`http://127.0.0.1:${controlPort}`)
+  const grants = await Promise.all([a.api.acquireSharedGpu(), b.api.acquireSharedGpu()])
+  assert.deepEqual(grants, [true, false])
+  a.active(true)
+  await a.api.maintainSharedGpu()
+  assert.equal((await fetch(`http://127.0.0.1:${proxyPort}/prompt`, { method:'POST', headers:a.api.sharedGpuHeaders(), body:'{}' })).status, 200)
+  assert.equal((await fetch(`http://127.0.0.1:${proxyPort}/interrupt`, { method:'POST', headers:{Authorization:'Bearer test-secret'}, body:'{}' })).status, 409)
+  assert.deepEqual(mutations, ['/prompt'])
+  busy = true
+  const queue = await (await fetch(`http://127.0.0.1:${proxyPort}/queue`)).json()
+  assert.deepEqual(queue, { queue_running: [null], queue_pending: [] })
+  assert.equal(JSON.stringify(queue).includes('private'), false)
+  assert.deepEqual(await (await fetch(`http://127.0.0.1:${proxyPort}/history`)).json(), {})
+  assert.equal(await b.api.acquireSharedGpu(), false)
+  // Saving still owns the reservation even after Comfy reports idle.
+  busy = false
+  assert.equal(await b.api.acquireSharedGpu(), false)
+  a.active(false); await a.api.maintainSharedGpu()
+  assert.equal(await a.api.acquireSharedGpu(), false, 'waiting B must run before another A job')
+  assert.equal(await b.api.acquireSharedGpu(), true)
+  assert.equal((await fetch(`http://127.0.0.1:${proxyPort}/prompt`, { method:'POST', headers:b.api.sharedGpuHeaders(), body:'{}' })).status, 200)
+  // A reset cannot even enter its local clear routine while B owns the device.
+  await assert.rejects(a.api.withSharedGpuReset(async () => assert.fail('must not clear jobs')), {statusCode:409})
+  b.active(false); await b.api.maintainSharedGpu()
+})
+
+test('missing coordinator cannot silently fall back to uncoordinated generation', async () => {
+  const c = client('http://127.0.0.1:1')
+  assert.equal(await c.api.acquireSharedGpu(), false)
+  await assert.rejects(c.api.assertSharedGpu(), {statusCode:409})
+  assert.throws(() => c.api.sharedGpuHeaders(), {statusCode:409})
+})
diff --git a/tests/studio-queue.test.mjs b/tests/studio-queue.test.mjs
index b93e2cb..1188f26 100644
--- a/tests/studio-queue.test.mjs
+++ b/tests/studio-queue.test.mjs
@@ -27,6 +27,7 @@ function fixture({ rows = [], lives = [], queue = { running: 0, pending: 0 }, hi
   const timers = []
   const started = []
   const modules = {
+    '~/server/utils/sharedGpu': { withSharedGpuStart: async fn => fn(), maintainSharedGpu: async () => {}, acquireSharedGpu: async () => false, sharedGpuWaitReason: () => 'GPU is in use. Waiting for availability.' },
     '~/server/utils/jobs': {
       listJobs: () => lives,
       getJob: id => lives.find(job => job.id === id),