diff --git a/crates/oak-render/examples/bench_playback.rs b/crates/oak-render/examples/bench_playback.rs
index 269029d40..8b7dcb841 100644
--- a/crates/oak-render/examples/bench_playback.rs
+++ b/crates/oak-render/examples/bench_playback.rs
@@ -39,9 +39,7 @@ use std::time::{Duration, Instant};
 
 use oak_core::{PixelFormat, Rational};
 use oak_render::procpool::{DispatcherConfig, ProcessDispatcher};
-use oak_render::ticket::{
-	Completion, Producer, TicketPayload, TicketResult, VideoTicketParams,
-};
+use oak_render::ticket::{Completion, Producer, TicketPayload, TicketResult, VideoTicketParams};
 use oak_render::worker::{Job, JobDispatch, JobSchedule};
 
 /// The comparison frame format: both backends must produce the same
@@ -80,10 +78,7 @@ fn cpu_times() -> (f64, f64) {
 	}
 	let self_times = rusage(libc::RUSAGE_SELF);
 	let children = rusage(libc::RUSAGE_CHILDREN);
-	(
-		self_times.0 + children.0,
-		self_times.1 + children.1,
-	)
+	(self_times.0 + children.0, self_times.1 + children.1)
 }
 
 /// One footage ticket over the whole timeline.
@@ -141,10 +136,7 @@ fn report(entries: &[(i64, Instant, Instant)], start: Instant, elapsed: Duration
 			),
 		);
 	}
-	report(
-		"cpu user + sys",
-		format!("{:.2} + {:.2} s", cpu.0, cpu.1),
-	);
+	report("cpu user + sys", format!("{:.2} + {:.2} s", cpu.0, cpu.1));
 	report(
 		"main-heap frame copies",
 		oak_render::procpool::main_heap_frame_copies().to_string(),
@@ -182,7 +174,12 @@ fn run_processes(media: &str, frames: usize, width: i32, height: i32, workers: O
 		let job = Job {
 			node_identity: 1,
 			time: Rational::new(frame, 25),
-			params: Arc::new(footage_params(&media_clone, Rational::new(frame, 25), width, height)),
+			params: Arc::new(footage_params(
+				&media_clone,
+				Rational::new(frame, 25),
+				width,
+				height,
+			)),
 			audio: None,
 			produce: Arc::new(|_, _| {
 				Err(oak_render::error::Error::Failed(
@@ -191,10 +188,11 @@ fn run_processes(media: &str, frames: usize, width: i32, height: i32, workers: O
 			}),
 			done: Box::new(move |result: TicketResult| match result {
 				Ok(TicketPayload::ShmFrame(f)) => {
-					results
-						.lock()
-						.unwrap_or_else(|e| e.into_inner())
-						.push((frame, start, Instant::now()));
+					results.lock().unwrap_or_else(|e| e.into_inner()).push((
+						frame,
+						start,
+						Instant::now(),
+					));
 					dc.release_frame(&f);
 				}
 				Ok(TicketPayload::ShmAudio(a)) => {
@@ -208,6 +206,7 @@ fn run_processes(media: &str, frames: usize, width: i32, height: i32, workers: O
 				}
 			}),
 			schedule: JobSchedule::playback(frame, frame, 0),
+			cancelled: None,
 		};
 		if !dispatcher.post(job) {
 			eprintln!("post refused at frame {frame}");
@@ -262,25 +261,30 @@ fn run_pipeline(media: &str, frames: usize, width: i32, height: i32) {
 		let submitted = Instant::now();
 		let done: Completion = Box::new(move |result: TicketResult| {
 			if let Ok(TicketPayload::Video(_)) = result {
-				results
-					.lock()
-					.unwrap_or_else(|e| e.into_inner())
-					.push((frame, submitted, Instant::now()));
+				results.lock().unwrap_or_else(|e| e.into_inner()).push((
+					frame,
+					submitted,
+					Instant::now(),
+				));
 			}
 		});
-		let producer: Producer =
-			Arc::new(|time, params| {
-				oak_render::eval::render_produced_frame(time, params)
-					.map(TicketPayload::Video)
-			});
+		let producer: Producer = Arc::new(|time, params| {
+			oak_render::eval::render_produced_frame(time, params).map(TicketPayload::Video)
+		});
 		let job = Job {
 			node_identity: 1,
 			time: Rational::new(frame, 25),
-			params: Arc::new(footage_params(media, Rational::new(frame, 25), width, height)),
+			params: Arc::new(footage_params(
+				media,
+				Rational::new(frame, 25),
+				width,
+				height,
+			)),
 			audio: None,
 			produce: producer,
 			done,
 			schedule: JobSchedule::playback(frame, frame, 0),
+			cancelled: None,
 		};
 		// The blocking post is the pipeline's backpressure: once the render
 		// queue is full the submitter waits (the app's window is capped by
@@ -332,7 +336,9 @@ fn main() {
 		.nth(4)
 		.and_then(|s| s.parse().ok())
 		.unwrap_or(480);
-	let mode = std::env::args().nth(5).unwrap_or_else(|| "processes".to_string());
+	let mode = std::env::args()
+		.nth(5)
+		.unwrap_or_else(|| "processes".to_string());
 
 	// The app's preview proxy size: the sequence's aspect scaled to the
 	// long edge (demo.mp4 is 16:9 1080p).
diff --git a/crates/oak-render/examples/bench_process.rs b/crates/oak-render/examples/bench_process.rs
index c71f36be1..9ca61dccb 100644
--- a/crates/oak-render/examples/bench_process.rs
+++ b/crates/oak-render/examples/bench_process.rs
@@ -57,8 +57,7 @@ fn worker_bin() -> PathBuf {
 		// target/<profile>/examples/bench_process -> target/<profile>/oak-worker
 		if let Some(examples) = exe.parent() {
 			if let Some(profile) = examples.parent() {
-				let candidate =
-					profile.join(format!("oak-worker{}", std::env::consts::EXE_SUFFIX));
+				let candidate = profile.join(format!("oak-worker{}", std::env::consts::EXE_SUFFIX));
 				if candidate.exists() {
 					return candidate;
 				}
@@ -91,9 +90,7 @@ fn main() {
 	let dispatcher = ProcessDispatcher::new(config).expect("dispatcher config");
 	dispatcher.start().expect("workers start + handshake");
 	let worker_count = dispatcher.worker_count();
-	println!(
-		"oak-worker pool: {worker_count} worker(s), {frames} x {width}x{height} BGRA8 frames"
-	);
+	println!("oak-worker pool: {worker_count} worker(s), {frames} x {width}x{height} BGRA8 frames");
 
 	// One completion record per frame: (frame number, wall-clock completion).
 	let results = Arc::new(Mutex::new(Vec::<(i64, Instant)>::new()));
@@ -152,6 +149,7 @@ fn main() {
 			// Playback priority: the pre-render window schedule (seek/playback
 			// prioritization is what the scheduler benchmark measures).
 			schedule: JobSchedule::playback(frame, 0, 0),
+			cancelled: None,
 		};
 		if !dispatcher.post(job) {
 			eprintln!("post refused at frame {frame}");
@@ -175,7 +173,11 @@ fn main() {
 	}
 	let elapsed = start.elapsed();
 
-	let mut entries: Vec<(i64, Instant)> = results.lock().unwrap_or_else(|e| e.into_inner()).drain(..).collect();
+	let mut entries: Vec<(i64, Instant)> = results
+		.lock()
+		.unwrap_or_else(|e| e.into_inner())
+		.drain(..)
+		.collect();
 	entries.sort_by_key(|(id, _)| *id);
 	let completed = entries.len();
 	let throughput = completed as f64 / elapsed.as_secs_f64();
@@ -195,18 +197,30 @@ fn main() {
 	};
 	report("frames completed", completed.to_string());
 	report("total wall time", format!("{:.2} s", elapsed.as_secs_f64()));
-	report("throughput", format!("{throughput:.1} fps ({:.1} ms/frame)", 1000.0 / throughput));
+	report(
+		"throughput",
+		format!("{throughput:.1} fps ({:.1} ms/frame)", 1000.0 / throughput),
+	);
 	if !deltas.is_empty() {
 		let mean = deltas.iter().sum::<f64>() / deltas.len() as f64;
 		let p95 = deltas[((deltas.len() as f64 * 0.95) as usize).min(deltas.len() - 1)];
 		report("adjacent-frame delta (pairs)", deltas.len().to_string());
-		report("  max", format!("{:.3} ms", deltas.last().unwrap() * 1000.0));
+		report(
+			"  max",
+			format!("{:.3} ms", deltas.last().unwrap() * 1000.0),
+		);
 		report("  mean", format!("{:.3} ms", mean * 1000.0));
 		report("  p95", format!("{:.3} ms", p95 * 1000.0));
 	} else {
-		report("adjacent-frame delta", "no adjacent pairs completed".to_string());
+		report(
+			"adjacent-frame delta",
+			"no adjacent pairs completed".to_string(),
+		);
 	}
-	report("main-heap frame copies", oak_render::procpool::main_heap_frame_copies().to_string());
+	report(
+		"main-heap frame copies",
+		oak_render::procpool::main_heap_frame_copies().to_string(),
+	);
 
 	dispatcher.shutdown();
 }
diff --git a/crates/oak-render/src/autocacher.rs b/crates/oak-render/src/autocacher.rs
index a007bb126..fb81eaa1c 100644
--- a/crates/oak-render/src/autocacher.rs
+++ b/crates/oak-render/src/autocacher.rs
@@ -139,8 +139,15 @@ impl PreviewAutoCacher {
 	}
 
 	/// Start a caching job for `range` of `owner`.
+	///
+	/// M4 priority fix: the range job is Background (§3.3 交互 > 播放 >
+	/// 导出 > 自动缓存). It used to go through `submit_video` (Seek), which
+	/// after the M4 seek over-admission let every autocache frame jump
+	/// ahead of playback *and* past the render-queue bound. The
+	/// interactive single-frame preview ([`PreviewAutoCacher::single_frame`])
+	/// keeps Seek.
 	fn start_range_job(&mut self, owner: u64, range: TimeRange) {
-		let id = self.arena.submit_video(
+		let id = self.arena.submit_video_background(
 			VideoTicketParams {
 				viewer: owner,
 				project: String::new(),
@@ -324,6 +331,44 @@ mod tests {
 		(PreviewAutoCacher::new(arena), d)
 	}
 
+	/// A dispatcher that records the posted schedules instead of running
+	/// them (the priority test only needs the posted `JobSchedule`).
+	#[derive(Default)]
+	struct RecordingDispatcher {
+		schedules: Mutex<Vec<crate::worker::JobSchedule>>,
+	}
+
+	impl JobDispatch for RecordingDispatcher {
+		fn post(&self, job: crate::worker::Job) -> bool {
+			lock(&self.schedules).push(job.schedule);
+			true
+		}
+
+		fn shutdown(&self) {}
+	}
+
+	#[test]
+	fn range_jobs_are_background_and_single_frames_stay_seek() {
+		let d = Arc::new(RecordingDispatcher::default());
+		let arena = Arc::new(TicketArena::new(d.clone(), frame_producer()));
+		let mut c = PreviewAutoCacher::new(arena);
+		c.attach(7).unwrap();
+		c.on_cache_request(7, TimeRange::new(Rational::new(0, 1), Rational::new(10, 1)));
+		c.single_frame(Rational::new(0, 1));
+		let schedules = lock(&d.schedules);
+		assert_eq!(schedules.len(), 2, "one range job + one single frame");
+		assert_eq!(
+			schedules[0].priority,
+			crate::scheduler::FramePriority::Background,
+			"autocache must yield to playback (§3.3)"
+		);
+		assert_eq!(
+			schedules[1].priority,
+			crate::scheduler::FramePriority::Seek,
+			"the interactive single-frame preview stays Seek"
+		);
+	}
+
 	#[test]
 	fn attach_detach_lifecycle() {
 		let (mut c, d) = new_cacher();
@@ -418,7 +463,6 @@ mod tests {
 		stop: AtomicU32,
 	}
 
-
 	#[test]
 	fn events_deliver_progress() {
 		let (mut c, d) = new_cacher();
diff --git a/crates/oak-render/src/pipeline.rs b/crates/oak-render/src/pipeline.rs
index ff4179827..5fbbccdab 100644
--- a/crates/oak-render/src/pipeline.rs
+++ b/crates/oak-render/src/pipeline.rs
@@ -96,10 +96,15 @@ pub const RENDER_QUEUE_CAP: usize = 8;
 /// path to the media, but still small enough to bound latency.
 pub const DECODE_QUEUE_CAP: usize = 16;
 
-/// Decoded-frame LRU capacity, in frames (~31 MB each at 1080p F32, so a
-/// handful of frames is already hundreds of MB). Sized for a playback
-/// window plus the montage baseline; the M2 decoder work lands here.
-pub const DECODE_LRU_CAP: usize = 8;
+/// Decoded-frame LRU capacity, in frames (~33 MB each at 1080p F32, so a
+/// small hand-off buffer, not a cache of record). The eval-side
+/// `decoded_frames` LRU (24 frames) is the cache of record; this one only
+/// bridges the decode thread and the render request. Keeping it at the
+/// read-ahead window bounds the double-cache overhead: at 1080p F32 the
+/// service copy stays ~2 frames instead of 8 (~200 MB saved). A request
+/// the hand-off missed is served from the eval cache without a decode —
+/// only the deep copy is paid again.
+pub const DECODE_LRU_CAP: usize = 2;
 
 fn lock<T>(m: &Mutex<T>) -> MutexGuard<'_, T> {
 	m.lock().unwrap_or_else(|e| e.into_inner())
@@ -388,7 +393,10 @@ impl DecodeService {
 			return false;
 		}
 		if self.enqueue(DecodeCommand::Prefetch { request }, false) {
-			self.inner.counters.prefetches.fetch_add(1, Ordering::Relaxed);
+			self.inner
+				.counters
+				.prefetches
+				.fetch_add(1, Ordering::Relaxed);
 			true
 		} else {
 			self.inner
@@ -506,7 +514,14 @@ fn serve(
 		return Ok(texture);
 	}
 	let texture = decode(request, inner)?;
-	lru_insert(lru, request.clone(), texture.clone(), lru_capacity, inner, tick);
+	lru_insert(
+		lru,
+		request.clone(),
+		texture.clone(),
+		lru_capacity,
+		inner,
+		tick,
+	);
 	inner.lru_len.store(lru.len(), Ordering::Relaxed);
 	Ok(texture)
 }
@@ -670,9 +685,8 @@ impl PipelineBackend {
 		// Prefetch is allowed only while the render queue has room: it must
 		// never fill the decode queue behind a saturated pipeline.
 		let gate_depth = depth.clone();
-		let gate: PrefetchGate = Arc::new(move || {
-			gate_depth.load(Ordering::Relaxed) < RENDER_QUEUE_CAP
-		});
+		let gate: PrefetchGate =
+			Arc::new(move || gate_depth.load(Ordering::Relaxed) < RENDER_QUEUE_CAP);
 		let decode = DecodeService::new(DECODE_LRU_CAP, gate);
 		let inner = Arc::new(PipelineInner {
 			queue: Mutex::new(VecDeque::new()),
@@ -687,7 +701,9 @@ impl PipelineBackend {
 			executed: AtomicU64::new(0),
 			drained: AtomicU64::new(0),
 		});
-		let backend = Arc::new(Self { inner: inner.clone() });
+		let backend = Arc::new(Self {
+			inner: inner.clone(),
+		});
 		let handle = std::thread::Builder::new()
 			.name("oak-render".into())
 			.spawn(move || render_loop(inner))
@@ -797,7 +813,9 @@ impl PipelineBackend {
 			inner.depth.store(0, Ordering::Relaxed);
 			jobs
 		};
-		inner.drained.fetch_add(jobs.len() as u64, Ordering::Relaxed);
+		inner
+			.drained
+			.fetch_add(jobs.len() as u64, Ordering::Relaxed);
 		inner.work.notify_all();
 		inner.room.notify_all();
 		for job in jobs {
@@ -921,8 +939,7 @@ mod tests {
 			"oakrender_pipeline_{tag}_{}.mp4",
 			std::process::id()
 		));
-		oak_codec::testmedia::write_test_clip(&path, 64, 64, 10, 10)
-			.expect("test clip generation");
+		oak_codec::testmedia::write_test_clip(&path, 64, 64, 10, 10).expect("test clip generation");
 		path
 	}
 
@@ -971,7 +988,9 @@ mod tests {
 			let off = y * stride + x * 16;
 			let mut out = [0f32; 4];
 			for i in 0..4 {
-				out[i] = f32::from_le_bytes(frame.data[off + i * 4..off + i * 4 + 4].try_into().unwrap());
+				out[i] = f32::from_le_bytes(
+					frame.data[off + i * 4..off + i * 4 + 4].try_into().unwrap(),
+				);
 			}
 			out
 		};
@@ -981,7 +1000,10 @@ mod tests {
 		assert!(r > 0.5 && g < 0.4 && b < 0.4, "{tag}: red half {r},{g},{b}");
 		assert!(a > 0.9, "{tag}: opaque {a}");
 		let [r, g, b, a] = read((48 - shift).rem_euclid(64) as usize, 32);
-		assert!(b > 0.5 && r < 0.4 && g < 0.4, "{tag}: blue half {r},{g},{b}");
+		assert!(
+			b > 0.5 && r < 0.4 && g < 0.4,
+			"{tag}: blue half {r},{g},{b}"
+		);
 		assert!(a > 0.9, "{tag}: opaque {a}");
 	}
 
@@ -1056,8 +1078,7 @@ mod tests {
 		let err = service
 			.request(req)
 			.expect("service available")
-			.err()
-			.expect("decoding a missing file must fail");
+			.expect_err("decoding a missing file must fail");
 		let _ = err.code(); // an explainable error, not a panic
 		let stats = service.stats();
 		assert_eq!(stats.errors, 1);
@@ -1108,9 +1129,10 @@ mod tests {
 		let path = test_clip("gate");
 		let open = Arc::new(AtomicBool::new(false));
 		let gate_open = open.clone();
-		let service = DecodeService::new(DECODE_LRU_CAP, Arc::new(move || {
-			gate_open.load(Ordering::Relaxed)
-		}));
+		let service = DecodeService::new(
+			DECODE_LRU_CAP,
+			Arc::new(move || gate_open.load(Ordering::Relaxed)),
+		);
 
 		let req = request(&path, Rational::new(1, 10));
 		assert!(!service.prefetch(req.clone()), "closed gate refuses");
@@ -1136,7 +1158,10 @@ mod tests {
 	fn wait_idle_barrier_covers_queued_commands() {
 		pin_legacy_working_space();
 		let path = test_clip("barrier");
-		let service = DecodeService::new(DECODE_LRU_CAP, always());
+		// The barrier test needs four live entries; the production
+		// hand-off capacity is deliberately tiny (see DECODE_LRU_CAP), so
+		// this test sizes its own service.
+		let service = DecodeService::new(4, always());
 		for n in 0..4 {
 			assert!(service.prefetch(request(&path, Rational::new(n, 10))));
 		}
@@ -1158,7 +1183,9 @@ mod tests {
 		let service = DecodeService::new(DECODE_LRU_CAP, always());
 		service.shutdown();
 		service.shutdown(); // idempotent
-		assert!(service.request(request(&path, Rational::new(0, 1))).is_none());
+		assert!(service
+			.request(request(&path, Rational::new(0, 1)))
+			.is_none());
 		assert!(!service.prefetch(request(&path, Rational::new(0, 1))));
 		assert!(!service.wait_idle());
 		let _ = std::fs::remove_file(&path);
@@ -1195,6 +1222,7 @@ mod tests {
 				distance: frame,
 				version: 0,
 			},
+			cancelled: None,
 		}
 	}
 
@@ -1302,15 +1330,29 @@ mod tests {
 			cache_timebase: None,
 			footage: None,
 			montage: vec![
-				clip("covered.mp4", Rational::new(0, 1), Rational::new(1, 1), Rational::new(2, 1)),
-				clip("outside.mp4", Rational::new(1, 1), Rational::new(2, 1), Rational::new(0, 1)),
+				clip(
+					"covered.mp4",
+					Rational::new(0, 1),
+					Rational::new(1, 1),
+					Rational::new(2, 1),
+				),
+				clip(
+					"outside.mp4",
+					Rational::new(1, 1),
+					Rational::new(2, 1),
+					Rational::new(0, 1),
+				),
 			],
 			adjustments: Vec::new(),
 		};
 		let requests = playback_decode_requests(&params, Rational::new(5, 10));
 		assert_eq!(requests.len(), 1, "only the covering clip is prefetched");
 		assert_eq!(requests[0].filename, "covered.mp4");
-		assert_eq!(requests[0].time, Rational::new(5, 2), "media_in + (time - in)");
+		assert_eq!(
+			requests[0].time,
+			Rational::new(5, 2),
+			"media_in + (time - in)"
+		);
 		assert_eq!(requests[0].size, (64, 32));
 		assert_eq!(requests[0].format, PixelFormat::F32);
 
diff --git a/crates/oak-render/src/ticket.rs b/crates/oak-render/src/ticket.rs
index 8406e0b7f..422e422ff 100644
--- a/crates/oak-render/src/ticket.rs
+++ b/crates/oak-render/src/ticket.rs
@@ -465,6 +465,7 @@ impl TicketArena {
 		let params = Arc::new(params);
 		let producer = self.producer.clone();
 		let slot_done = slot.clone();
+		let slot_cancelled = slot.clone();
 		let job = crate::worker::Job {
 			node_identity: params.viewer,
 			time: params.time,
@@ -473,6 +474,13 @@ impl TicketArena {
 			produce: producer,
 			done: Box::new(move |result| slot_done.finish(result)),
 			schedule,
+			// Audit B: let the dispatcher skip producing a frame whose
+			// ticket was cancelled after posting (exactly-once delivery is
+			// unchanged — `finish` still fires, here with the same
+			// `Error::State` a cancelled result would get).
+			cancelled: Some(Arc::new(move || {
+				slot_cancelled.cancel.load(Ordering::Acquire)
+			})),
 		};
 		if !self.dispatch.post(job) {
 			// Backend is gone (shutdown raced the submit): deliver now.
@@ -507,11 +515,7 @@ impl TicketArena {
 
 	/// Submit a Background-priority frame (M15 S2 exports/precache): the
 	/// scheduler renders it whenever no Seek/Playback work is pending.
-	pub fn submit_video_background(
-		&self,
-		params: VideoTicketParams,
-		done: Completion,
-	) -> TicketId {
+	pub fn submit_video_background(&self, params: VideoTicketParams, done: Completion) -> TicketId {
 		let id = self.next_id();
 		self.submit_video_background_with_id(id, params, done)
 	}
@@ -590,6 +594,7 @@ impl TicketArena {
 		let make_job = |slot_done: Arc<TicketSlot>| {
 			let ap_job = ap.clone();
 			let ap_prod = ap.clone();
+			let slot_cancelled = slot_done.clone();
 			let producer: Producer = Arc::new(move |_, _| eval::render_audio_samples(&ap_prod));
 			crate::worker::Job {
 				node_identity: viewer,
@@ -612,6 +617,9 @@ impl TicketArena {
 				produce: producer,
 				done: Box::new(move |result| slot_done.finish(result)),
 				schedule: JobSchedule::seek(),
+				cancelled: Some(Arc::new(move || {
+					slot_cancelled.cancel.load(Ordering::Acquire)
+				})),
 			}
 		};
 		let job = make_job(slot.clone());
diff --git a/crates/oak-render/src/worker.rs b/crates/oak-render/src/worker.rs
index c8d210be3..d0a392fc9 100644
--- a/crates/oak-render/src/worker.rs
+++ b/crates/oak-render/src/worker.rs
@@ -69,6 +69,11 @@ pub struct Job {
 	pub done: Completion,
 	/// Scheduler hints (M15 S2). Defaults to a Seek single-frame request.
 	pub schedule: JobSchedule,
+	/// Mid-flight cancellation probe (audit B): when it returns true the
+	/// dispatcher must finish the job with `Error::State` without running
+	/// the producer. The ticket arena installs the slot's cancel atom;
+	/// hand-built jobs (tests, non-ticket callers) pass `None`.
+	pub cancelled: Option<Arc<dyn Fn() -> bool + Send + Sync>>,
 }
 
 /// Scheduler hints a posted job carries (M15 S2). The process dispatcher
@@ -234,8 +239,14 @@ impl InlineDispatcher {
 
 /// Run one job on the calling thread: the producer, then its completion
 /// (used by the inline dispatcher and by [`crate::pipeline::PipelineBackend`],
-/// which runs the same producer on its render thread).
+/// which runs the same producer on its render thread). A job the arena
+/// already cancelled (audit B) is short-circuited with `Error::State` —
+/// a cancelled frame must not burn render/GPU work only to be discarded.
 pub(crate) fn execute_job(job: Job) {
+	if job.cancelled.as_ref().is_some_and(|cancelled| cancelled()) {
+		(job.done)(Err(Error::State));
+		return;
+	}
 	let result = catch_unwind(AssertUnwindSafe(|| (job.produce)(job.time, &job.params)))
 		.unwrap_or_else(|_| Err(Error::Failed("frame producer panicked".into())));
 	(job.done)(result);
@@ -302,8 +313,8 @@ impl GraphSnapshotStore {
 			"oakrender-snapshots-{}-{:x}",
 			std::process::id(),
 			{
-                use std::sync::atomic::{AtomicU64, Ordering};
-                static SEQ: AtomicU64 = AtomicU64::new(0);
+				use std::sync::atomic::{AtomicU64, Ordering};
+				static SEQ: AtomicU64 = AtomicU64::new(0);
 				SEQ.fetch_add(1, Ordering::Relaxed)
 			}
 		));
@@ -350,9 +361,10 @@ impl GraphSnapshotStore {
 		// Atomic staging: temp file + rename. The rename is a single
 		// directory entry swap, so a concurrent worker load observes
 		// either the old file or the complete new one.
-		let tmp = self
-			.dir
-			.join(format!("graph-{uuid}-{revision}.{}.tmp", std::process::id()));
+		let tmp = self.dir.join(format!(
+			"graph-{uuid}-{revision}.{}.tmp",
+			std::process::id()
+		));
 		std::fs::write(&tmp, &xml)
 			.map_err(|e| Error::Failed(format!("write snapshot temp: {e}")))?;
 		if let Err(e) = std::fs::rename(&tmp, &path) {
@@ -390,9 +402,10 @@ impl GraphSnapshotStore {
 		let path = self.dir.join(format!("graph-{uuid}-{revision}.xml"));
 		let path_str = path.to_string_lossy().into_owned();
 		// Atomic staging: temp file + rename (see [`acquire`]).
-		let tmp = self
-			.dir
-			.join(format!("graph-{uuid}-{revision}.{}.tmp", std::process::id()));
+		let tmp = self.dir.join(format!(
+			"graph-{uuid}-{revision}.{}.tmp",
+			std::process::id()
+		));
 		std::fs::write(&tmp, &xml)
 			.map_err(|e| Error::Failed(format!("write snapshot temp: {e}")))?;
 		if let Err(e) = std::fs::rename(&tmp, &path) {
@@ -466,13 +479,13 @@ impl Default for GraphSnapshotStore {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
-    use std::sync::mpsc;
-    use std::time::Duration;
+	use super::*;
+	use std::sync::mpsc;
+	use std::time::Duration;
 
-    use oak_core::texture::Texture;
+	use oak_core::texture::Texture;
 
-    fn job(tag: u64, tx: mpsc::Sender<u64>, gate: Option<Arc<AtomicBool>>) -> Job {
+	fn job(tag: u64, tx: mpsc::Sender<u64>, gate: Option<Arc<AtomicBool>>) -> Job {
 		let produce: Producer = Arc::new(move |_, _| {
 			if let Some(g) = &gate {
 				if g.load(Ordering::Acquire) {
@@ -505,6 +518,7 @@ mod tests {
 				let _ = tx.send(tag);
 			}),
 			schedule: JobSchedule::seek(),
+			cancelled: None,
 		}
 	}
 
@@ -552,7 +566,8 @@ mod tests {
 		let (tx, rx) = mpsc::channel();
 		for _ in 0..4 {
 			let tx = tx.clone();
-			let p: Producer = Arc::new(|_, _| Ok(crate::ticket::TicketPayload::Video(Texture::dummy())));
+			let p: Producer =
+				Arc::new(|_, _| Ok(crate::ticket::TicketPayload::Video(Texture::dummy())));
 			d.post(Job {
 				node_identity: 1,
 				time: Rational::new(0, 1),
@@ -576,6 +591,7 @@ mod tests {
 					let _ = tx.send(r.is_err());
 				}),
 				schedule: JobSchedule::seek(),
+				cancelled: None,
 			});
 		}
 		drop(tx);
@@ -585,7 +601,10 @@ mod tests {
 			delivered.push(err);
 		}
 		assert_eq!(delivered.len(), 4, "all queued completions fire");
-		assert!(delivered.iter().all(|&e| e), "queued jobs cancel at shutdown");
+		assert!(
+			delivered.iter().all(|&e| e),
+			"queued jobs cancel at shutdown"
+		);
 	}
 
 	#[test]
@@ -594,7 +613,8 @@ mod tests {
 		let (tx, rx) = mpsc::channel();
 		let tx1 = tx.clone();
 		let boom: Producer = Arc::new(|_, _| panic!("boom"));
-		let ok: Producer = Arc::new(|_, _| Ok(crate::ticket::TicketPayload::Video(Texture::dummy())));
+		let ok: Producer =
+			Arc::new(|_, _| Ok(crate::ticket::TicketPayload::Video(Texture::dummy())));
 		let params = Arc::new(VideoTicketParams {
 			viewer: 0,
 			project: String::new(),
@@ -620,6 +640,7 @@ mod tests {
 				let _ = tx1.send(1u64);
 			}),
 			schedule: JobSchedule::seek(),
+			cancelled: None,
 		});
 		d.post(Job {
 			node_identity: 1,
@@ -632,6 +653,7 @@ mod tests {
 				let _ = tx.send(2u64);
 			}),
 			schedule: JobSchedule::seek(),
+			cancelled: None,
 		});
 		let mut got = Vec::new();
 		while let Ok(v) = rx.recv_timeout(Duration::from_secs(5)) {
@@ -681,10 +703,7 @@ mod tests {
 		// First snapshot: the default project (working space ACEScg).
 		let p1 = store.acquire(&project, 1).unwrap();
 		let before = std::fs::read_to_string(&p1).unwrap();
-		assert!(
-			std::path::Path::new(&p1).exists(),
-			"snapshot file written"
-		);
+		assert!(std::path::Path::new(&p1).exists(), "snapshot file written");
 		assert_eq!(store.refs(&p1), 1);
 
 		// A settings change with no revision bump: plain acquire must NOT
@@ -695,7 +714,11 @@ mod tests {
 		}
 		let p2 = store.acquire(&project, 1).unwrap();
 		assert_eq!(p1, p2, "same (uuid, revision) key reuses the file");
-		assert_eq!(std::fs::read_to_string(&p1).unwrap(), before, "acquire never rewrites");
+		assert_eq!(
+			std::fs::read_to_string(&p1).unwrap(),
+			before,
+			"acquire never rewrites"
+		);
 		store.release(&p2);
 
 		// ...while acquire_rewrite rewrites it in place at the same key.
diff --git a/crates/oak-render/tests/render_threads_test.rs b/crates/oak-render/tests/render_threads_test.rs
index a29f644b6..a86790cba 100644
--- a/crates/oak-render/tests/render_threads_test.rs
+++ b/crates/oak-render/tests/render_threads_test.rs
@@ -25,6 +25,7 @@
 //! and each creates and tears its manager down explicitly.
 
 use std::path::{Path, PathBuf};
+use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{mpsc, Arc, Condvar, Mutex, MutexGuard};
 use std::time::{Duration, Instant};
 
@@ -44,8 +45,7 @@ use oak_render::error::Error;
 use oak_render::eval::{decode_invocations, reset_decode_invocations};
 use oak_render::manager::{RenderBackendChoice, RenderManager};
 use oak_render::pipeline::{
-	decode_service, DecodeRequest, DecodeStats, PipelineBackend, PipelineStats,
-	RENDER_QUEUE_CAP,
+	decode_service, DecodeRequest, DecodeStats, PipelineBackend, PipelineStats, RENDER_QUEUE_CAP,
 };
 use oak_render::ticket::{
 	Completion, MontageClip, Producer, TicketPayload, TicketResult, VideoTicketParams,
@@ -71,8 +71,7 @@ fn test_clip(tag: &str) -> PathBuf {
 		"oakrender_threads_{tag}_{}.mp4",
 		std::process::id()
 	));
-	oak_codec::testmedia::write_test_clip(&path, 64, 64, 10, 10)
-		.expect("test clip generation");
+	oak_codec::testmedia::write_test_clip(&path, 64, 64, 10, 10).expect("test clip generation");
 	path
 }
 
@@ -211,7 +210,8 @@ fn assert_known_pattern(frame: &Frame, index: i32, tag: &str) {
 		let off = y * stride + x * 16;
 		let mut out = [0f32; 4];
 		for i in 0..4 {
-			out[i] = f32::from_le_bytes(frame.data[off + i * 4..off + i * 4 + 4].try_into().unwrap());
+			out[i] =
+				f32::from_le_bytes(frame.data[off + i * 4..off + i * 4 + 4].try_into().unwrap());
 		}
 		out
 	};
@@ -221,7 +221,10 @@ fn assert_known_pattern(frame: &Frame, index: i32, tag: &str) {
 	assert!(r > 0.5 && g < 0.4 && b < 0.4, "{tag}: red half {r},{g},{b}");
 	assert!(a > 0.9, "{tag}: opaque {a}");
 	let [r, g, b, a] = read((48 - shift).rem_euclid(64) as usize, 32);
-	assert!(b > 0.5 && r < 0.4 && g < 0.4, "{tag}: blue half {r},{g},{b}");
+	assert!(
+		b > 0.5 && r < 0.4 && g < 0.4,
+		"{tag}: blue half {r},{g},{b}"
+	);
 	assert!(a > 0.9, "{tag}: opaque {a}");
 }
 
@@ -306,10 +309,9 @@ fn filler_job() -> Job {
 		Path::new("/definitely/not/here-filler.mp4"),
 		Rational::new(0, 1),
 	));
-	let produce: Producer =
-		Arc::new(|_time: Rational, _params: &VideoTicketParams| -> TicketResult {
-			Err(Error::State)
-		});
+	let produce: Producer = Arc::new(
+		|_time: Rational, _params: &VideoTicketParams| -> TicketResult { Err(Error::State) },
+	);
 	Job {
 		node_identity: 0,
 		time: Rational::new(0, 1),
@@ -318,6 +320,7 @@ fn filler_job() -> Job {
 		produce,
 		done: Box::new(|_result: TicketResult| {}),
 		schedule: JobSchedule::seek(),
+		cancelled: None,
 	}
 }
 
@@ -468,8 +471,18 @@ fn build_layered_project(
 		// V1: A [0,1) + transition [0.5,1.5) + B [1,2).
 		let (v1_core, v1_beh) = TrackBehavior::create();
 		let v1 = p.graph.add_node(v1_core, v1_beh);
-		let a = add_clip(&mut p.graph, first, Rational::new(0, 1), Rational::new(1, 1));
-		let b = add_clip(&mut p.graph, second, Rational::new(1, 1), Rational::new(2, 1));
+		let a = add_clip(
+			&mut p.graph,
+			first,
+			Rational::new(0, 1),
+			Rational::new(1, 1),
+		);
+		let b = add_clip(
+			&mut p.graph,
+			second,
+			Rational::new(1, 1),
+			Rational::new(2, 1),
+		);
 		let (tcore, tbehavior) = oak_node::block::transition_create();
 		let transition = p.graph.add_node(tcore, tbehavior);
 		{
@@ -507,7 +520,12 @@ fn build_layered_project(
 		// V2: C [0,2), overlapping the transition track.
 		let (v2_core, v2_beh) = TrackBehavior::create();
 		let v2 = p.graph.add_node(v2_core, v2_beh);
-		let c = add_clip(&mut p.graph, below, Rational::new(0, 1), Rational::new(2, 1));
+		let c = add_clip(
+			&mut p.graph,
+			below,
+			Rational::new(0, 1),
+			Rational::new(2, 1),
+		);
 		track_mut(&mut p.graph, v2).append_block(c);
 
 		// V3: an adjustment layer [0,2) with an Opacity(0.75) chain.
@@ -774,7 +792,8 @@ fn pipeline_graph_playback_has_zero_gpu_readbacks() {
 #[test]
 fn pipeline_layered_playback_has_zero_gpu_readbacks() {
 	let _lock = lock();
-	if oak_core::backend::shared_gpu_or_skip("the layered playback zero-readback assertion").is_none()
+	if oak_core::backend::shared_gpu_or_skip("the layered playback zero-readback assertion")
+		.is_none()
 	{
 		return;
 	}
@@ -899,10 +918,7 @@ fn parked_producer(
 		while !*released {
 			released = work.wait(released).unwrap_or_else(|e| e.into_inner());
 		}
-		order
-			.lock()
-			.unwrap_or_else(|e| e.into_inner())
-			.push(tag);
+		order.lock().unwrap_or_else(|e| e.into_inner()).push(tag);
 		Err(Error::State)
 	})
 }
@@ -910,10 +926,7 @@ fn parked_producer(
 /// A producer that records `tag` when the render thread runs it and fails.
 fn recording_producer(order: Arc<Mutex<Vec<&'static str>>>, tag: &'static str) -> Producer {
 	Arc::new(move |_time: Rational, _params: &VideoTicketParams| {
-		order
-			.lock()
-			.unwrap_or_else(|e| e.into_inner())
-			.push(tag);
+		order.lock().unwrap_or_else(|e| e.into_inner()).push(tag);
 		Err(Error::State)
 	})
 }
@@ -928,6 +941,7 @@ fn scheduled_job(produce: Producer, schedule: JobSchedule) -> Job {
 		produce,
 		done: Box::new(|_result: TicketResult| {}),
 		schedule,
+		cancelled: None,
 	}
 }
 
@@ -950,12 +964,7 @@ fn pipeline_orders_seek_ahead_of_background_end_to_end() {
 	let started = Arc::new((Mutex::new(false), Condvar::new()));
 	let release = Arc::new((Mutex::new(false), Condvar::new()));
 
-	let produce = parked_producer(
-		started.clone(),
-		release.clone(),
-		order.clone(),
-		"in-flight",
-	);
+	let produce = parked_producer(started.clone(), release.clone(), order.clone(), "in-flight");
 	assert!(
 		backend.try_post(scheduled_job(produce, JobSchedule::playback(0, 0, 0))),
 		"the in-flight playback frame is accepted"
@@ -1044,6 +1053,7 @@ fn pipeline_prefetch_is_the_frame_the_render_request_uses() {
 			let _ = done_tx.send(matches!(result, Ok(TicketPayload::Video(_))));
 		}),
 		schedule: JobSchedule::playback(0, 0, 0),
+		cancelled: None,
 	};
 	assert!(backend.post(playback), "the playback frame is accepted");
 	assert!(
@@ -1051,7 +1061,10 @@ fn pipeline_prefetch_is_the_frame_the_render_request_uses() {
 		"the read-ahead decode completes while the render thread is parked"
 	);
 	let after_prefetch = service.stats();
-	assert_eq!(after_prefetch.prefetches, 1, "the post queued one read-ahead");
+	assert_eq!(
+		after_prefetch.prefetches, 1,
+		"the post queued one read-ahead"
+	);
 	assert_eq!(after_prefetch.decodes, 1, "the read-ahead decoded once");
 
 	open_gate(&release);
@@ -1098,10 +1111,9 @@ fn pipeline_cancel_preview_frame_matches_the_sequence() {
 	let (tx, rx) = mpsc::channel();
 	for identity in [1u64, 2] {
 		let tx = tx.clone();
-		let produce: Producer =
-			Arc::new(|_time: Rational, _params: &VideoTicketParams| {
-				Ok(TicketPayload::Video(Texture::dummy()))
-			});
+		let produce: Producer = Arc::new(|_time: Rational, _params: &VideoTicketParams| {
+			Ok(TicketPayload::Video(Texture::dummy()))
+		});
 		let job = Job {
 			node_identity: identity,
 			time: Rational::new(0, 1),
@@ -1113,6 +1125,7 @@ fn pipeline_cancel_preview_frame_matches_the_sequence() {
 			}),
 			// Same frame number, same version — only the sequence differs.
 			schedule: JobSchedule::playback(5, 0, 0),
+			cancelled: None,
 		};
 		assert!(backend.post(job), "viewer {identity}'s frame is queued");
 	}
@@ -1135,6 +1148,48 @@ fn pipeline_cancel_preview_frame_matches_the_sequence() {
 	backend.shutdown();
 }
 
+/// Audit B: a job whose ticket was cancelled after posting must not run
+/// its producer. The arena installs `Job.cancelled` from the slot's cancel
+/// atom; this hand-built job pins the dispatcher behaviour and the
+/// exactly-once completion (`Error::State`).
+#[test]
+fn pipeline_skips_a_cancelled_job() {
+	let _lock = lock();
+	let backend = PipelineBackend::new().expect("pipeline backend starts");
+	let ran = Arc::new(AtomicBool::new(false));
+	let flag = Arc::new(AtomicBool::new(true));
+	let ran_producer = ran.clone();
+	let produce: Producer = Arc::new(move |_time: Rational, _params: &VideoTicketParams| {
+		ran_producer.store(true, Ordering::Release);
+		Ok(TicketPayload::Video(Texture::dummy()))
+	});
+	let probe = flag.clone();
+	let (tx, rx) = mpsc::channel();
+	let job = Job {
+		node_identity: 0,
+		time: Rational::new(0, 1),
+		params: Arc::new(base_params(Rational::new(0, 1))),
+		audio: None,
+		produce,
+		done: Box::new(move |result: TicketResult| {
+			let _ = tx.send(result.is_err());
+		}),
+		schedule: JobSchedule::seek(),
+		cancelled: Some(Arc::new(move || probe.load(Ordering::Acquire))),
+	};
+	assert!(backend.try_post(job), "the cancelled job is still accepted");
+	assert!(
+		rx.recv_timeout(Duration::from_secs(10))
+			.expect("the completion fires exactly once"),
+		"a cancelled job completes with Error::State"
+	);
+	assert!(
+		!ran.load(Ordering::Acquire),
+		"the producer must not run for a cancelled job"
+	);
+	backend.shutdown();
+}
+
 /// A saturated render queue closes the decode service's prefetch gate: a
 /// speculative decode must be refused while a frame is in flight and the
 /// queue is full, and everything queued must still run once the in-flight
@@ -1158,8 +1213,12 @@ fn pipeline_queue_backpressure_closes_the_prefetch_gate() {
 		move |_time: Rational, _params: &VideoTicketParams| -> TicketResult {
 			{
 				let (name, work) = &*job_started;
-				*name.lock().unwrap_or_else(|e| e.into_inner()) =
-					Some(std::thread::current().name().unwrap_or_default().to_string());
+				*name.lock().unwrap_or_else(|e| e.into_inner()) = Some(
+					std::thread::current()
+						.name()
+						.unwrap_or_default()
+						.to_string(),
+				);
 				work.notify_all();
 			}
 			let (released, work) = &*job_release;
@@ -1181,21 +1240,21 @@ fn pipeline_queue_backpressure_closes_the_prefetch_gate() {
 		produce,
 		done: Box::new(|_result: TicketResult| {}),
 		schedule: JobSchedule::seek(),
+		cancelled: None,
 	};
 
 	assert!(backend.try_post(hold_job), "the in-flight job is accepted");
-	wait_until("the render thread to pick up the in-flight job", &mut || {
-		started
-			.0
-			.lock()
-			.unwrap_or_else(|e| e.into_inner())
-			.is_some()
-	});
-	let thread_name = started
-		.0
-		.lock()
-		.unwrap_or_else(|e| e.into_inner())
-		.clone();
+	wait_until(
+		"the render thread to pick up the in-flight job",
+		&mut || {
+			started
+				.0
+				.lock()
+				.unwrap_or_else(|e| e.into_inner())
+				.is_some()
+		},
+	);
+	let thread_name = started.0.lock().unwrap_or_else(|e| e.into_inner()).clone();
 	assert_eq!(
 		thread_name.as_deref(),
 		Some("oak-render"),
@@ -1238,8 +1297,7 @@ fn pipeline_queue_backpressure_closes_the_prefetch_gate() {
 		work.notify_all();
 	}
 	wait_until("every queued job to execute", &mut || {
-		backend.stats().executed == RENDER_QUEUE_CAP as u64 + 1
-			&& backend.queue_depth() == 0
+		backend.stats().executed == RENDER_QUEUE_CAP as u64 + 1 && backend.queue_depth() == 0
 	});
 	let stats = backend.stats();
 	assert_eq!(
@@ -1249,11 +1307,11 @@ fn pipeline_queue_backpressure_closes_the_prefetch_gate() {
 	);
 
 	backend.shutdown();
+	assert!(!backend.try_post(filler_job()), "shutdown rejects new work");
 	assert!(
-		!backend.try_post(filler_job()),
-		"shutdown rejects new work"
+		decode_service().is_none(),
+		"shutdown uninstalls the service"
 	);
-	assert!(decode_service().is_none(), "shutdown uninstalls the service");
 }
 
 /// The backend owns the process-wide decode service slot: it is installed
@@ -1274,8 +1332,5 @@ fn pipeline_installs_and_uninstalls_the_decode_service() {
 		decode_service().is_none(),
 		"shutdown uninstalls the decode service"
 	);
-	assert!(
-		!backend.try_post(filler_job()),
-		"shutdown rejects new work"
-	);
+	assert!(!backend.try_post(filler_job()), "shutdown rejects new work");
 }
diff --git a/crates/oak-worker/tests/procpool_integration.rs b/crates/oak-worker/tests/procpool_integration.rs
index a432f26fd..dfedf82b9 100644
--- a/crates/oak-worker/tests/procpool_integration.rs
+++ b/crates/oak-worker/tests/procpool_integration.rs
@@ -42,9 +42,7 @@ use oak_render::ipc::SLOT_FORMAT_BGRA8;
 use oak_render::procpool::{
 	main_heap_frame_copies, reset_main_heap_frame_copies, DispatcherConfig, ProcessDispatcher,
 };
-use oak_render::ticket::{
-	AudioTicketParams, TicketPayload, TicketResult, VideoTicketParams,
-};
+use oak_render::ticket::{AudioTicketParams, TicketPayload, TicketResult, VideoTicketParams};
 use oak_render::worker::{Job, JobDispatch, JobSchedule};
 
 /// Serialize every test in this file (shared process environment +
@@ -117,9 +115,13 @@ fn submit(
 				))
 			}),
 			done: Box::new(move |result| {
-				results.lock().unwrap_or_else(|e| e.into_inner()).push(result);
+				results
+					.lock()
+					.unwrap_or_else(|e| e.into_inner())
+					.push(result);
 			}),
 			schedule: JobSchedule::seek(),
+			cancelled: None,
 		};
 		assert!(dispatcher.post(job), "post accepted while alive");
 	}
@@ -166,8 +168,11 @@ fn pool_resize_drains_shrunk_workers_and_regrows() {
 	let deadline = Instant::now() + Duration::from_secs(60);
 	while completed < 12 {
 		dispatcher.poll();
-		let drained: Vec<TicketResult> =
-			results.lock().unwrap_or_else(|e| e.into_inner()).drain(..).collect();
+		let drained: Vec<TicketResult> = results
+			.lock()
+			.unwrap_or_else(|e| e.into_inner())
+			.drain(..)
+			.collect();
 		for result in drained {
 			let payload = result.expect("frame rendered");
 			let TicketPayload::ShmFrame(frame) = payload else {
@@ -181,7 +186,10 @@ fn pool_resize_drains_shrunk_workers_and_regrows() {
 		}
 		std::thread::sleep(Duration::from_millis(2));
 	}
-	assert_eq!(completed, 12, "all tickets completed before the resize settles");
+	assert_eq!(
+		completed, 12,
+		"all tickets completed before the resize settles"
+	);
 	// The pool reached the target (the shrink took effect).
 	assert_eq!(dispatcher.worker_count(), 1);
 	// Let the retired children exit naturally (their EOF is reaped on
@@ -200,8 +208,11 @@ fn pool_resize_drains_shrunk_workers_and_regrows() {
 	let results2 = Arc::new(Mutex::new(Vec::new()));
 	submit(&dispatcher, &results2, 6, None);
 	pump_until(&dispatcher, &results2, 6);
-	let frames: Vec<TicketResult> =
-		results2.lock().unwrap_or_else(|e| e.into_inner()).drain(..).collect();
+	let frames: Vec<TicketResult> = results2
+		.lock()
+		.unwrap_or_else(|e| e.into_inner())
+		.drain(..)
+		.collect();
 	assert_eq!(frames.len(), 6, "the regrown pool renders a new wave");
 	for result in frames {
 		let payload = result.expect("regrown wave rendered");
@@ -237,8 +248,11 @@ fn two_workers_render_two_waves_zero_copy() {
 	let deadline = Instant::now() + Duration::from_secs(60);
 	while completed < 12 {
 		dispatcher.poll();
-		let drained: Vec<TicketResult> =
-			results.lock().unwrap_or_else(|e| e.into_inner()).drain(..).collect();
+		let drained: Vec<TicketResult> = results
+			.lock()
+			.unwrap_or_else(|e| e.into_inner())
+			.drain(..)
+			.collect();
 		for result in drained {
 			let payload = result.expect("frame rendered");
 			let TicketPayload::ShmFrame(frame) = payload else {
@@ -304,10 +318,8 @@ fn crash_isolation_restarts_worker_and_frame_still_renders() {
 	// One-shot crash hook: the worker dies with SIGSEGV while rendering
 	// ticket 1; the marker file it leaves behind makes the restarted
 	// worker render the re-queued frame for real.
-	let marker = std::env::temp_dir().join(format!(
-		"oak-procpool-crash-marker-{}",
-		std::process::id()
-	));
+	let marker =
+		std::env::temp_dir().join(format!("oak-procpool-crash-marker-{}", std::process::id()));
 	let _ = std::fs::remove_file(&marker);
 	std::env::set_var("OAK_WORKER_CRASH_ON_TICKET", "1");
 	std::env::set_var("OAK_WORKER_CRASH_MARKER", &marker);
@@ -387,7 +399,9 @@ fn worker_decodes_real_footage_into_slot() {
 		// Decoded video is opaque: every BGRA alpha byte is 255.
 		let pixels = &frame.shm.slot_bytes(frame.slot)[..frame.meta.data_size as usize];
 		let alpha_ok = pixels
-			.chunks_exact(4)
+			.as_chunks::<4>()
+			.0
+			.iter()
 			.filter(|px| px[3] == 255)
 			.count();
 		assert!(
@@ -431,10 +445,7 @@ fn montage_effects_render_through_the_worker() {
 			type_id: "org.olivevideoeditor.Olive.opacity".into(),
 			enabled: true,
 			effect_input_id: Some("tex_in".into()),
-			params: vec![(
-				"opacity_in".into(),
-				oak_node::value::NodeValue::Float(0.5),
-			)],
+			params: vec![("opacity_in".into(), oak_node::value::NodeValue::Float(0.5))],
 		}])],
 	];
 
@@ -455,9 +466,13 @@ fn montage_effects_render_through_the_worker() {
 				))
 			}),
 			done: Box::new(move |result| {
-				results.lock().unwrap_or_else(|e| e.into_inner()).push(result);
+				results
+					.lock()
+					.unwrap_or_else(|e| e.into_inner())
+					.push(result);
 			}),
 			schedule: JobSchedule::seek(),
+			cancelled: None,
 		};
 		assert!(dispatcher.post(job), "post accepted while alive");
 	}
@@ -480,7 +495,9 @@ fn montage_effects_render_through_the_worker() {
 	};
 	// Pick an opaque, non-black pixel in the plain render as the probe.
 	let probe = plain
-		.chunks_exact(4)
+		.as_chunks::<4>()
+		.0
+		.iter()
 		.position(|px| px[3] == 255 && px[0] > 40)
 		.expect("the fixture frame has an opaque non-black pixel");
 	let p = &plain[probe * 4..probe * 4 + 4];
@@ -549,9 +566,13 @@ fn submit_audio(
 			))
 		}),
 		done: Box::new(move |result| {
-			results.lock().unwrap_or_else(|e| e.into_inner()).push(result);
+			results
+				.lock()
+				.unwrap_or_else(|e| e.into_inner())
+				.push(result);
 		}),
 		schedule: JobSchedule::seek(),
+		cancelled: None,
 	};
 	assert!(dispatcher.post(job), "post accepted while alive");
 }
@@ -572,7 +593,13 @@ fn audio_tickets_roundtrip_through_shm_slots() {
 	// 1/24 s at 48 kHz stereo = 2000 sample frames x 2 ch = 16000 bytes —
 	// fits the 64x64 BGRA8 slot (16384 bytes).
 	for i in 0..4 {
-		submit_audio(&dispatcher, &results, 1, Rational::new(i, 24), Rational::new(1, 24));
+		submit_audio(
+			&dispatcher,
+			&results,
+			1,
+			Rational::new(i, 24),
+			Rational::new(1, 24),
+		);
 	}
 	pump_until(&dispatcher, &results, 4);
 
@@ -590,7 +617,10 @@ fn audio_tickets_roundtrip_through_shm_slots() {
 		// Empty montage: total silence, parsed back as f32.
 		let samples = audio.samples();
 		assert_eq!(samples.len(), 2000 * 2);
-		assert!(samples.iter().all(|&v| v == 0.0), "empty montage is silence");
+		assert!(
+			samples.iter().all(|&v| v == 0.0),
+			"empty montage is silence"
+		);
 		// Audio tickets are Seek priority — claimable by ANY worker (the
 		// seek-starvation fix), so there is no shard-spread assertion; what
 		// matters is that every ticket rendered on a live worker.
@@ -692,7 +722,13 @@ fn audio_crash_isolation_restarts_worker_and_audio_still_renders() {
 	// The dispatcher's first ticket id is 1 — exactly the crash ticket
 	// (an audio ticket this time).
 	for i in 0..4 {
-		submit_audio(&dispatcher, &results, 1, Rational::new(i, 24), Rational::new(1, 24));
+		submit_audio(
+			&dispatcher,
+			&results,
+			1,
+			Rational::new(i, 24),
+			Rational::new(1, 24),
+		);
 	}
 	pump_until(&dispatcher, &results, 4);
 
@@ -769,6 +805,7 @@ fn oversized_audio_ticket_is_refused_by_process_backend() {
 			results2.lock().unwrap_or_else(|e| e.into_inner()).push(());
 		}),
 		schedule: JobSchedule::seek(),
+		cancelled: None,
 	};
 	assert!(
 		!dispatcher.post(job),
@@ -792,7 +829,12 @@ fn f32_ticket_gets_f32_slot_and_bgra8_stays_bgra8() {
 	let results = Arc::new(Mutex::new(Vec::new()));
 	submit(&dispatcher, &results, 1, None);
 	pump_until(&dispatcher, &results, 1);
-	let bg = results.lock().unwrap().pop().unwrap().expect("frame rendered");
+	let bg = results
+		.lock()
+		.unwrap()
+		.pop()
+		.unwrap()
+		.expect("frame rendered");
 	let TicketPayload::ShmFrame(frame) = bg else {
 		panic!("ShmFrame payload");
 	};
@@ -829,14 +871,23 @@ fn f32_ticket_gets_f32_slot_and_bgra8_stays_bgra8() {
 				))
 			}),
 			done: Box::new(move |result| {
-				results2.lock().unwrap_or_else(|e| e.into_inner()).push(result);
+				results2
+					.lock()
+					.unwrap_or_else(|e| e.into_inner())
+					.push(result);
 			}),
 			schedule: JobSchedule::seek(),
+			cancelled: None,
 		};
 		assert!(dispatcher.post(job), "f32 post accepted");
 	}
 	pump_until(&dispatcher, &results2, 1);
-	let f32res = results2.lock().unwrap().pop().unwrap().expect("f32 frame rendered");
+	let f32res = results2
+		.lock()
+		.unwrap()
+		.pop()
+		.unwrap()
+		.expect("f32 frame rendered");
 	let TicketPayload::ShmFrame(frame) = f32res else {
 		panic!("ShmFrame payload");
 	};
@@ -845,7 +896,9 @@ fn f32_ticket_gets_f32_slot_and_bgra8_stays_bgra8() {
 	// The F32 bytes are zero (transparent black pipeline output).
 	let pixels = frame.shm.slot_bytes(frame.slot);
 	assert!(
-		pixels[..frame.meta.data_size as usize].iter().all(|&b| b == 0),
+		pixels[..frame.meta.data_size as usize]
+			.iter()
+			.all(|&b| b == 0),
 		"generated F32 frame is transparent black"
 	);
 	dispatcher.release_frame(&frame);
@@ -854,7 +907,12 @@ fn f32_ticket_gets_f32_slot_and_bgra8_stays_bgra8() {
 	//    segment (the wire format is per ticket).
 	submit(&dispatcher, &results, 1, None);
 	pump_until(&dispatcher, &results, 1);
-	let bg2 = results.lock().unwrap().pop().unwrap().expect("frame rendered");
+	let bg2 = results
+		.lock()
+		.unwrap()
+		.pop()
+		.unwrap()
+		.expect("frame rendered");
 	let TicketPayload::ShmFrame(frame) = bg2 else {
 		panic!("ShmFrame payload");
 	};
@@ -892,7 +950,12 @@ fn build_graph_project(clip: &std::path::Path) -> (Arc<Mutex<Project>>, NodeId)
 		let (ccore, cbehavior) = oak_node::block::clip_create();
 		let clip_node = p.graph.add_node(ccore, cbehavior);
 		p.graph
-			.connect(footage, clip_node, oak_node::block::clip_input::TEXTURE_INPUT, -1)
+			.connect(
+				footage,
+				clip_node,
+				oak_node::block::clip_input::TEXTURE_INPUT,
+				-1,
+			)
 			.expect("connect footage to clip");
 
 		let clip_behavior = p
@@ -974,9 +1037,13 @@ fn post_graph_job(
 			))
 		}),
 		done: Box::new(move |result| {
-			results.lock().unwrap_or_else(|e| e.into_inner()).push(result);
+			results
+				.lock()
+				.unwrap_or_else(|e| e.into_inner())
+				.push(result);
 		}),
 		schedule: JobSchedule::seek(),
+		cancelled: None,
 	};
 	assert!(dispatcher.post(job), "post accepted while alive");
 }
@@ -995,7 +1062,12 @@ fn assert_graph_frame_opaque(dispatcher: &ProcessDispatcher, payload: TicketResu
 	assert_eq!(frame.meta.format, SLOT_FORMAT_BGRA8);
 	assert_eq!(frame.meta.data_size, 64 * 64 * 4);
 	let pixels = &frame.shm.slot_bytes(frame.slot)[..frame.meta.data_size as usize];
-	let alpha_ok = pixels.chunks_exact(4).filter(|px| px[3] == 255).count();
+	let alpha_ok = pixels
+		.as_chunks::<4>()
+		.0
+		.iter()
+		.filter(|px| px[3] == 255)
+		.count();
 	assert!(
 		alpha_ok as f64 >= 0.99 * (64 * 64) as f64,
 		"graph-rendered frame must be opaque ({alpha_ok}/4096)"
@@ -1042,11 +1114,19 @@ fn graph_mode_renders_sequence_viewer_from_snapshot() {
 	dispatcher.start().expect("worker starts");
 
 	let results = Arc::new(Mutex::new(Vec::new()));
-	let project_uuid = project.lock().unwrap_or_else(|e| e.into_inner()).uuid.clone();
+	let project_uuid = project
+		.lock()
+		.unwrap_or_else(|e| e.into_inner())
+		.uuid
+		.clone();
 	post_graph_job(&dispatcher, &results, viewer, &project_uuid);
 	pump_until(&dispatcher, &results, 1);
 
-	let result = results.lock().unwrap_or_else(|e| e.into_inner()).pop().unwrap();
+	let result = results
+		.lock()
+		.unwrap_or_else(|e| e.into_inner())
+		.pop()
+		.unwrap();
 	assert_graph_frame_opaque(&dispatcher, result);
 
 	dispatcher.shutdown();
@@ -1088,11 +1168,19 @@ fn set_graph_snapshot_after_start_reroutes_tickets() {
 	dispatcher.set_graph_snapshot(Some(snapshot.display().to_string()));
 
 	let results = Arc::new(Mutex::new(Vec::new()));
-	let project_uuid = project.lock().unwrap_or_else(|e| e.into_inner()).uuid.clone();
+	let project_uuid = project
+		.lock()
+		.unwrap_or_else(|e| e.into_inner())
+		.uuid
+		.clone();
 	post_graph_job(&dispatcher, &results, viewer, &project_uuid);
 	pump_until(&dispatcher, &results, 1);
 
-	let result = results.lock().unwrap_or_else(|e| e.into_inner()).pop().unwrap();
+	let result = results
+		.lock()
+		.unwrap_or_else(|e| e.into_inner())
+		.pop()
+		.unwrap();
 	assert_graph_frame_opaque(&dispatcher, result);
 
 	dispatcher.shutdown();
diff --git a/docs/zh/plans/render-pipeline-threads.md b/docs/zh/plans/render-pipeline-threads.md
index 47fe525d1..f15b5dea9 100644
--- a/docs/zh/plans/render-pipeline-threads.md
+++ b/docs/zh/plans/render-pipeline-threads.md
@@ -273,6 +273,20 @@
 >   生效——若 Seek 被挡在门外，UI 会等一个导出/缓存帧跑完。`cancel_preview_frame`
 >   丢弃已过 playhead 的排队帧，按 `(sequence, frame, version)` 全键匹配
 >   （两个监视器可同帧号同版本，只按帧匹配会误杀另一序列）。
+> - 自动缓存优先级修正：`PreviewAutoCacher::start_range_job` 改走
+>   `submit_video_background`（Background），不再以 Seek 插到播放之前——
+>   否则 Seek 超额插队会让逐张 autocache 帧绕过队列容量约束、倒挂
+>   §3.3 的"交互 > 播放 > 导出 > 自动缓存"；`single_frame` 交互帧保持
+>   Seek（`range_jobs_are_background_and_single_frames_stay_seek`）。
+> - 取消即停（审计 B）：`Job.cancelled` 钩子由 arena 从 slot 的 cancel 原子
+>   安装，`execute_job` 在生产前检查——`TicketArena::cancel` 之后仍未开跑的
+>   帧直接以 `Error::State` 完成，不再烧一遍 GPU/CPU 再丢弃；交付仍是
+>   exactly-once（`pipeline_skips_a_cancelled_job` 断言 producer 未运行）。
+> - 双份帧缓存（审计 C）：eval 内层 `decoded_frames`（24 帧）才是缓存主拷贝，
+>   `DecodeService` LRU 只是解码线程→渲染请求的交接缓冲，已由 8 帧降到
+>   `DECODE_LRU_CAP=2`；1080p F32 下副缓存常驻 ~8×33MB → ~2×33MB，交接
+>   未命中由 eval 缓存兜底（不再解码，只多一次拷贝）。彻底合并两份缓存需
+>   让 Texture/缓存持有共享 Arc 帧，另行立项。
 > - **基准对比**（本机 release，`oak-render/examples/bench_playback`，
 >   1080p/25fps MPEG-2 源、240 帧@480p(853×480) / 128 帧@1080p；两个后端
 >   统一输出 F32 帧、同尺寸，否则进程池的 BGRA8 槽位与管线的 in-process