Two strands from the "Windows host went Offline after reconnect, zero errors in
the logs" investigation.
Crash visibility — the field reports kept arriving with nothing in the Logs
tab because every way the host can die silently was unlogged:
- A panic hook tees each panic (thread, location, backtrace) through `tracing`
into the in-memory ring + host.log before the default hook runs — a panicking
thread otherwise only hit stderr, absent from the web console and gone when
stderr is detached.
- A last-resort Windows SEH filter (windows/crash.rs) logs an unhandled native
exception with its code, faulting address, and faulting MODULE — the smoking
gun that separates our bug from a GPU runtime/driver DLL (amfrt64, the UMD,
d3d11) crashing under us.
- A 10 s watchdog around the vdisplay monitor teardown logs an ERROR when the
driver REMOVE/CCD-restore looks wedged (it runs under the manager state lock,
so a hang there silently blocks every future acquire).
Deliberate-quit teardown (Windows pf-vdisplay) — the Windows manager never
wired the linger skip the Linux registry has: on ⌘D (the QUIT close code) the
monitor lingered 10 s, so a quick reconnect hit the Lingering-preempt's
back-to-back REMOVE→ADD churn. A per-lease quit flag (VirtualDisplay::
set_quit_flag) now tears the monitor down immediately on a deliberate quit, so
the reconnect finds the manager Idle and does a clean fresh ADD.
Pin outranks quit (both platforms) — keep_alive=forever (the gaming-rig preset)
promises "the screen stays alive", so a deliberate quit must skip only the
linger WINDOW, never the pin. Windows release() checks keep_alive_forever()
before the quit; the Linux registry had the inverse bug (force_immediate tore
down even a pinned display) — fixed via effective_linger() with a unit test.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
