I'm investigating repeated WindowServer watchdog kernel panics on a Mac mini M6 running macOS 27.0.1 (build 26A434), and would appreciate technical guidance on identifying the initiating failure. System configuration Mac mini M6, 16 GB unified memory macOS 27.0.1 (26A434) Redmi G Pro 27U external monitor Physical output: 3840 × 2160 @ 160 Hz, RGB 10-bit HDR10 USB-C-to-DisplayPort 1.4 direct connection, HBR3 ×4, DSC enabled Similar system-level crashes have occurred over both HDMI and DisplayPort The system has experienced repeated freezes and forced restarts over several days. Kernel panic signature userspace watchdog timeout: no successful checkins from WindowServer in 120 seconds WindowServer initialization not complete (post IOKitWaitQuiet)Some WindowServer recovery diagnostics involve IOMobileFramebuffer and IOMobileGraphicsFamily-DCP. Latest incident: October 24, 2026 (UTC+08:00) At 01:33:25.578, the unified log began recording repeated messages: DCPEXT1:GMailboxHandler.cpp:232 apt firmware: immediate_swap_denied landed frame_id = 1, reason = 1At 01:33:35.612, WindowServer reported: [Watchdog] display 1 has become stuck after 10.00154s of unreadiness (2463 failures)Approximately 14,264 immediate_swap_denied messages were recorded in the retrieved interval ending at 01:34:55, followed by a system restart around 01:35. The corresponding panic report is: panic-full-2026-10-24-013618.0002.panic What I have checked The failures are not limited to one video connection type. The physical display signal is 4K 160 Hz, not 5K 160 Hz. The 5120 × 2880 value reported by HiDPI utilities represents the internal scaling buffer. Crashes occurred before BetterDisplay was first used. The latest incident occurred while viewing a remote desktop stream, but available process-count samples did not reveal proliferation of the remote-control processes. Memory/resource pressure remains under investigation; there is not enough evidence to attribute the panics to memory exhaustion. It is unclear whether the initial WindowServer stall precedes or follows the DCP frame-swap errors. Questions What does immediate_swap_denied with frame_id=1, reason=1 indicate in the Apple DCP display pipeline? Can this error be a downstream symptom of an already-stalled WindowServer, or does it suggest a DCP/display frame-submission failure? Is there a known macOS 27 issue involving WindowServer watchdog failures or recovery stalls in IOMobileGraphicsFamily-DCP? What additional diagnostics would help distinguish a macOS display firmware/driver problem from external-display compatibility, memory pressure, or defective hardware? I can provide the panic report, WindowServer diagnostic samples, relevant unified-log extracts, display configuration information, and a sysdiagnose through Feedback Assistant. Feedback Assistant report: FB25300098 Any guidance from Apple DTS engineers or developers who have encountered a similar DCP/WindowServer failure would be appreciated.