User observed: 'display disconnected' + freeze with NO context change, and
'first switch happy, subsequent slower, then chaos under stress'. Log shows the
cause: MONITOR_GUID was a FIXED constant, so overlapping sessions (a client
RECONNECTING after a freeze before the old session tore down, or concurrent
sessions) all map to the SAME SudoVDA monitor (same GUID -> IOCTL_ADD reuses
target 257). When the old session ends, its IOCTL_REMOVE tears the monitor down
OUT FROM UNDER the live session -> 'display disconnected' + the late
E_INVALIDARG/MODE_CHANGE failures (output vanished mid-session) -> cascade.
Fix: next_monitor_guid() returns a unique GUID per (process, session) [base GUID
with low 48-bit node = pid<<16 | session#]; create() threads it into AddParams
AND the keepalive (which REMOVEs by it). Each session now owns its own monitor;
one ending can't kill another. (The 200ms DuplicateOutput1 retry confirmed
working — 'succeeded on retry' logged; the residual failures were this
collision, not the race.)
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
enricobuehler
2f7c021cac