diff --git a/package.json b/package.json
index a623fc3..9c994a3 100644
--- a/package.json
+++ b/package.json
@@ -3,6 +3,7 @@
   "private": true,
   "type": "module",
   "scripts": {
+    "test": "node --test tests/*.test.mjs",
     "build": "nuxt build",
     "dev": "nuxt dev --host 0.0.0.0 --port 3000",
     "preview": "nuxt preview --host 0.0.0.0 --port 3000",
diff --git a/server/utils/comfy.ts b/server/utils/comfy.ts
index d95c2bf..f66f6f0 100644
--- a/server/utils/comfy.ts
+++ b/server/utils/comfy.ts
@@ -211,7 +211,9 @@ export async function freeComfyVram() {
 }
 
 export async function fetchHistory(promptId: string) {
-  const res = await comfyFetch(`/history/${encodeURIComponent(promptId)}`)
+  const res = await comfyFetch(`/history/${encodeURIComponent(promptId)}`, {
+    signal: AbortSignal.timeout(12000)
+  })
   if (!res.ok) return null
   return (await res.json()) as Record<string, unknown>
 }
diff --git a/server/utils/studioQueue.ts b/server/utils/studioQueue.ts
index f73de79..059e13f 100644
--- a/server/utils/studioQueue.ts
+++ b/server/utils/studioQueue.ts
@@ -309,7 +309,14 @@ async function reapZombieLiveJobs() {
       if (jobAgeMs(job) >= QUEUED_GRACE_MS) failZombieLiveJob(job, 'Job never started on ComfyUI')
       continue
     }
-    const history = await fetchHistory(job.promptId).catch(() => null)
+    let history: Awaited<ReturnType<typeof fetchHistory>>
+    try {
+      history = await fetchHistory(job.promptId)
+    } catch {
+      // A failed history request is not evidence that Comfy lost the prompt.
+      continue
+    }
+    if (!history) continue
     const entry = history?.[job.promptId] as { status?: { status_str?: string; completed?: boolean } } | undefined
     if (!entry) {
       failZombieLiveJob(job, 'ComfyUI lost this job (empty queue after a restart or clear). Generate again.')
@@ -755,10 +762,9 @@ export async function retryStudioJob(owner: string, id: string) {
 
 function pruneDone(jobs: StudioJob[]) {
   const cutoff = Date.now() - 1000 * 60 * 60 * 24
-  return jobs.filter(job => {
-    if (job.status === 'waiting' || job.status === 'running' || job.status === 'held') return true
-    return job.updatedAt > cutoff
-  }).slice(-40)
+  const active = (job: StudioJob) => job.status === 'waiting' || job.status === 'running' || job.status === 'held'
+  const recentDone = new Set(jobs.filter(job => !active(job) && job.updatedAt > cutoff).slice(-40))
+  return jobs.filter(job => active(job) || recentDone.has(job))
 }
 
 export async function markStudioLive(owner: string, id: string, liveJobId: string, shotQueueId?: string) {
@@ -1599,12 +1605,12 @@ function findStudioRowForLive(jobs: StudioJob[], job: Job) {
     const byQueue = jobs.find(item => (
       item.shotQueueId === job.library?.queueId
       && item.status === 'running'
+      && !item.liveJobId
     ))
     if (byQueue) return byQueue
   }
-  // Last resort: sole running row for this owner (liveJobId lost after a restart).
-  const running = jobs.filter(item => item.status === 'running')
-  if (running.length === 1) return running[0]
+  // A delayed callback from an older job must never settle a newer running job.
+  // Missing associations are handled by repairStaleJobs, not guessed here.
   return undefined
 }
 
@@ -1704,7 +1710,9 @@ export async function onLiveVideoSettled(job: Job) {
     syncPausedFlag(store)
   })
 
-  await kickStudioQueue()
+  // Settlement is also called from inside dispatchStudioQueue's recovery checks.
+  // Awaiting a dispatch queued behind that same dispatch deadlocks the entire queue.
+  void kickStudioQueue()
 }
 
 function interruptedRunning(job: Job, remaining: number, userPause: boolean, cutInHold: boolean) {
diff --git a/tests/studio-queue.test.mjs b/tests/studio-queue.test.mjs
new file mode 100644
index 0000000..b93e2cb
--- /dev/null
+++ b/tests/studio-queue.test.mjs
@@ -0,0 +1,168 @@
+import test from 'node:test'
+import assert from 'node:assert/strict'
+import { createRequire } from 'node:module'
+import { mkdtempSync, mkdirSync, readFileSync, writeFileSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { execFileSync } from 'node:child_process'
+import ts from 'typescript'
+
+const require = createRequire(import.meta.url)
+const file = 'server/utils/studioQueue.ts'
+const source = process.env.TEST_BASELINE === '1'
+  ? execFileSync('git', ['show', `HEAD:${file}`], { encoding: 'utf8' })
+  : readFileSync(new URL(`../${file}`, import.meta.url), 'utf8')
+const compiled = ts.transpileModule(source, {
+  compilerOptions: { module: ts.ModuleKind.CommonJS, target: ts.ScriptTarget.ES2022 }
+}).outputText
+
+// Execute the real queue module against temporary stores and a fake GPU.
+// No production library, network, Comfy process, or render is touched.
+function fixture({ rows = [], lives = [], queue = { running: 0, pending: 0 }, history = {} } = {}) {
+  const root = mkdtempSync(join(tmpdir(), 'aigen-queue-test-'))
+  const owner = 'test-owner'
+  mkdirSync(join(root, 'users', owner), { recursive: true })
+  const path = join(root, 'users', owner, 'studio-queue.json')
+  writeFileSync(path, JSON.stringify({ paused: false, jobs: rows }))
+  const timers = []
+  const started = []
+  const modules = {
+    '~/server/utils/jobs': {
+      listJobs: () => lives,
+      getJob: id => lives.find(job => job.id === id),
+      emitJob: () => {}
+    },
+    '~/server/utils/pending': {
+      listPendingJobs: () => [], readPendingJob: () => undefined,
+      patchPendingJob: () => {}, deletePendingJob: () => {}
+    },
+    '~/server/utils/shotQueue': {
+      getShotQueue: () => null, pendingSegmentCount: () => 0
+    },
+    '~/server/utils/comfy': { fetchLiveQueue: async () => queue, fetchHistory: async () => {
+      if (history instanceof Error) throw history
+      return history
+    } },
+    '~/utils/videoModels': {
+      isLtxWorkflow: () => false, isTextToVideo: () => true, isXaigenStudio: () => false,
+      ltxWorkflowEnabled: () => true, parseVideoWorkflow: value => value
+    },
+    '~/server/utils/loras': { persistLoraFields: () => ({}) },
+    '~/utils/loras': { resolveLoraStack: () => [] },
+    '~/utils/promptParts': { persistPromptWrappers: () => ({}) },
+    '~/utils/imageV2': { imageV2StackSpecials: () => ({}) },
+    '~/utils/globalLocks': { allowIdentityRefs: () => false },
+    '~/server/utils/generationLog': { updateGenerationLogByStudioJob: async () => {} },
+    '~/server/utils/musicChain': {
+      startMusicJob: async () => {
+        const live = liveJob(`started-${started.length}`, 'music')
+        lives.push(live)
+        started.push(live)
+        return live
+      }
+    }
+  }
+  const localRequire = id => {
+    if (id.startsWith('node:')) return require(id)
+    if (modules[id]) return modules[id]
+    throw new Error(`Unexpected test dependency: ${id}`)
+  }
+  const exports = {}
+  new Function('require', 'exports', 'useRuntimeConfig', 'setTimeout', 'createError', compiled)(
+    localRequire, exports, () => ({ libraryDir: root }),
+    fn => { timers.push(fn); return timers.length },
+    info => Object.assign(new Error(info.statusMessage), info)
+  )
+  return { api: exports, rows: () => JSON.parse(readFileSync(path, 'utf8')).jobs, lives, started, timers }
+}
+function row(id, status = 'running', liveJobId = id) {
+  return { id, ownerKey: 'test-owner', status, liveJobId, kind: 'music',
+    createdAt: Date.now(), updatedAt: Date.now(), payload: { prompt: 'test', extensions: [] } }
+}
+function liveJob(id, kind = 'edit', extra = {}) {
+  return { id, kind, status: 'running', promptId: `prompt-${id}`, startedAt: Date.now() - 300_000,
+    library: { ownerKey: 'test-owner' }, ...extra }
+}
+async function finishes(promise) {
+  let timer
+  try {
+    await Promise.race([promise, new Promise((_, reject) => {
+      timer = setTimeout(() => reject(new Error('Queue dispatcher deadlocked')), 500)
+    })])
+  } finally { clearTimeout(timer) }
+}
+
+for (const kind of ['edit', 'music']) {
+  test(`${kind}: recover saved output and dispatch the next job without deadlocking`, async () => {
+    const live = liveJob('old', kind, kind === 'edit' ? { stillId: 'saved' } : { audio: { filename: 'saved.wav' } })
+    const f = fixture({ rows: [row('old'), row('next', 'waiting', undefined)], lives: [live],
+      history: { 'prompt-old': { status: { status_str: 'success', completed: true } } } })
+    await finishes(f.api.kickStudioQueue())
+    assert.equal(f.rows().find(job => job.id === 'old').status, 'complete')
+    assert.equal(f.rows().find(job => job.id === 'next').status, 'running')
+    assert.equal(f.started.length, 1)
+    await finishes(f.api.kickStudioQueue())
+    assert.equal(f.started.length, 1)
+  })
+}
+
+test('late settlement from an older job does not complete the next running job', async () => {
+  const current = liveJob('current')
+  const f = fixture({ rows: [row('current')], lives: [current], queue: { running: 1, pending: 0 } })
+  await finishes(f.api.onLiveVideoSettled(liveJob('old', 'music', { status: 'complete' })))
+  assert.equal(f.rows()[0].status, 'running')
+  assert.equal(f.rows()[0].liveJobId, 'current')
+})
+
+test('history pruning preserves all waiting, held, and running jobs above 40 rows', async () => {
+  const rows = Array.from({ length: 50 }, (_, i) => row(`waiting-${i}`, 'waiting'))
+  rows.unshift(row('held', 'held'), row('active'))
+  const f = fixture({ rows, lives: [liveJob('active')], queue: { running: 1, pending: 0 } })
+  await finishes(f.api.kickStudioQueue())
+  assert.equal(f.rows().length, 52)
+  assert.equal(f.rows()[0].id, 'held')
+})
+
+test('an old shot callback cannot settle a new live job attached to the same batch', async () => {
+  const current = liveJob('current')
+  current.library.queueId = 'batch'
+  const currentRow = { ...row('current'), shotQueueId: 'batch' }
+  const f = fixture({ rows: [currentRow], lives: [current], queue: { running: 1, pending: 0 } })
+  const old = liveJob('old', 'video', { status: 'complete' })
+  old.library.queueId = 'batch'
+  await finishes(f.api.onLiveVideoSettled(old))
+  assert.equal(f.rows()[0].status, 'running')
+  assert.equal(f.rows()[0].liveJobId, 'current')
+})
+
+test('an empty Comfy queue during output saving does not release the active job', async () => {
+  const f = fixture({ rows: [row('saving'), row('next', 'waiting')], lives: [liveJob('saving', 'video', { saving: true })] })
+  await finishes(f.api.kickStudioQueue())
+  assert.equal(f.started.length, 0)
+  assert.equal(f.rows()[0].status, 'running')
+  assert.equal(f.timers.length, 1)
+})
+
+test('a missing prompt is failed and the next job starts', async () => {
+  const f = fixture({ rows: [row('lost'), row('next', 'waiting')], lives: [liveJob('lost')] })
+  await finishes(f.api.kickStudioQueue())
+  await finishes(f.api.kickStudioQueue())
+  assert.equal(f.rows()[0].status, 'error')
+  assert.equal(f.started.length, 1)
+})
+
+test('a connection outage does not fail an attached running job', async () => {
+  const f = fixture({ rows: [row('active'), row('next', 'waiting')], lives: [liveJob('active')], queue: null })
+  await finishes(f.api.kickStudioQueue())
+  assert.equal(f.rows()[0].status, 'running')
+  assert.equal(f.started.length, 0)
+})
+
+for (const history of [new Error('history timed out'), null]) {
+  test(`a failed history lookup (${history ? 'timeout' : 'HTTP failure'}) does not discard a render`, async () => {
+    const f = fixture({ rows: [row('active'), row('next', 'waiting')], lives: [liveJob('active')], history })
+    await finishes(f.api.kickStudioQueue())
+    assert.equal(f.rows()[0].status, 'running')
+    assert.equal(f.started.length, 0)
+  })
+}