[butilly]

Diagnostic 1 for My Younger Sister is My Roommate v1.0, executable OmaNeko-Seikatsu.exe, thread 1566676500433076425. Two reports on Proton 11 ARM64EC and FEXCore 2605 Compatibility exit with c000001d at libarm64ecfex.dll+0x171BFC, five additional FEX frames, then ntdll and exe+0x1264. No game-process FEX logging, UnityPlayer, or graphics DLLs appear. FEX_SILENTLOG=0 and FEX_OUTPUTLOG=stderr did not expose a guest opcode; do not assume this is an unsupported guest instruction. Source review finds config loading precedes Logging::Init and LogMan traps silently without a handler. Add allocation-free Wine startup stage messages and temporary pre-config LogMan handlers after CRT initialization; uninstall before normal logging initialization. No instruction, exception, renderer, or configuration behavior is changed. Existing logs cover only later stages; no available channel captures these early boundaries. Next report: inspect FEX-STARTUP last stage and early error text, distinguishing config/CRT initialization from translation. Keep Proton major and architecture unchanged. git diff --check passed; compilation is validated by package CI. Root cause remains unconfirmed.