Developer finds sandbox misclassified shell crashes as command failures on Windows

A developer running an AI agent on Windows Server 2022 discovered that every executed command was silently failing due to a broken shell environment, not faulty commands. The root cause was a recent update that set bash as the default process-boundary shell across all platforms, despite bash not being a native Windows executable. Further investigation revealed that six bundled tools — including bash.exe — all depended on the msys2 runtime DLL, which was only present in one directory and causing STATUS_DLL_INIT_FAILED (exit code 0xC0000142) at the loader level. Because the runner's failure-detection logic did not recognise this exit code as an environment-level fault, every crash was logged as a normal command failure, masking the broken environment entirely. The developer concluded that runners should treat 'child process never initialised' as a runner failure and surface the exit code prominently in all error messages to prevent wasted retry attempts.