[LinuxJedi]

Problem

A bug report: on Windows 11 with an AMD GPU, resizing the main window hangs Copperline, and the whole machine is very slow until it recovers. It reproduces reliably.

Since 0.21.0 the present worker plans each frame on the main thread and presents it later. On Windows the main thread pumps the modal size-move loop while the user drags an edge, so the window changes size while frames are still queued for the worker. On Windows wgpu picks Vulkan first, and the driver returns VK_ERROR_OUT_OF_DATE_KHR when the swapchain extent no longer matches the window. pixels 0.17.2 retries that acquire in a loop with no bound, reconfiguring from its cached surface size. Only the main thread can update that size, and only after reclaiming the GPU side. So the worker rebuilt the swapchain at the stale size forever, while the main thread waited in PresentWorker::reclaim to apply the Resized event. The window stopped responding, and the swapchain churn starved the GPU driver.

This is the #362 loop again (fullscreen toggles on X11), now on a thread the corrective event cannot reach. The redraw-time resync from #362 does not cover it, because the size check runs on the main thread and the acquire runs on the worker. Single-threaded present never hit this on Windows: there the window can only change size while that same thread pumps messages.

Fix

• Each PresentJob records the surface size it was planned for. Before acquiring, the worker compares that size with the window's live size (worker_surface_current). If the window has changed size, the worker drops the job: it was drawn for the old geometry anyway. The Resized event behind the change reconfigures the surface on the main thread, and the next frame is planned for the new size. On macOS the worker must not call winit, and the Metal layer never reports a resized surface as out of date, so it presents as before.
• A resize can still land between that check and the acquire. To cover it, pixels is patched to upstream's bounded retry (Bound the retry loop while acquiring the surface texture parasyte/pixels#462, merged but unreleased; the pinned revision is 0.17.2 plus that change and an examples-only clippy pass). pixels now gives up after one reconfigure and returns GetSurface(Outdated). Both present paths log that at debug level as a dropped frame; other present failures are still errors.
• The patch is a revision-pinned [patch.crates-io] in the root, crates/copperline-player and fuzz workspaces (the ones that build pixels), with the source allowed in deny.toml. Remove all of them once a pixels release includes Add built-in General MIDI device #462. The lockfile changes only swap pixels' source line.
• docs/internals/video.md describes the worker-side check and the bounded retry.

Testing

• New unit tests: present_worker_drops_a_frame_the_window_has_resized_past and an_out_of_date_surface_is_a_dropped_frame_not_an_error.
• cargo test --release, cargo clippy --all-targets and cargo fmt --check are clean on macOS.
• Not yet run on Windows. The reporter's machine is the real test. Builds without this fix can avoid the hang with COPPERLINE_THREADED_PRESENT=0 or WGPU_BACKEND=dx12.

[Copilot]

🔵 Needs a closer look

The GPU-threading fix still needs resize validation on the affected Windows/Vulkan platform.

No open issues 🎉

What changed in this PR

Addresses resize-related presentation hangs by dropping stale worker frames and bounding surface-acquisition retries.

Changes:

• Check live window size before worker presentation.
• Pin the upstream pixels retry fix and log outdated surfaces as dropped frames.
• Add regression tests and update presentation documentation.

File	Description
src/​video/​window/​tests.rs	Tests stale-frame detection and error classification.
src/​video/​window/​present.rs	Adds size checks and present-error logging helpers.
src/​video/​window.rs	Records planned size and skips stale worker jobs.
fuzz/​Cargo.toml	Applies the pixels patch to fuzzing.
docs/​internals/​video.md	Documents resize handling and bounded retries.
deny.toml	Allows the upstream pixels Git source.
crates/​copperline-player/​Cargo.toml	Applies the pixels patch to the player.
crates/​copperline-player/​Cargo.lock	Pins the player's patched pixels source.
Cargo.toml	Pins the upstream bounded-retry patch.
Cargo.lock	Locks the patched pixels source.

_{Review effort: Balanced}