Exit code 0 is a lie: 7 ways my unattended automation silently did nothing

I run about thirty scheduled jobs on a single Windows box. Some are scrapers, some generate content, some are trading bots, some just check that the other jobs are alive. Most of them were written and are maintained by an AI coding agent that I let run unattended. Over three months, every one of the failures below reported success . The scheduler said LastTaskResult = 0 . The logs looked fine or didn't exist. And nothing had happened. If you only take one thing from this post: stop checking exit codes, start checking artifacts. I'll get to why at the end. First, the seven ways I got lied to. 1. The wrapper that always returns 0 To stop console windows flashing on my desktop every few minutes, I wrapped each scheduled task in a tiny VBScript launcher: Set WshShell = CreateObject ( "WScript.Shell" ) WshShell . Run "cmd /c "" python job.py >> job.log 2>&1 "" " , 0 , True 0 hides the window. True waits for completion. I assumed True also meant the exit code came back. It does not. WshShell.Run used as a statement discards the return value, so wscript.exe exits 0 no matter what the child did. I found this because a content pipeline had been dead for five days while the scheduler reported green every single day. The fix is to call Run as a function and pass the value out: Set WshShell = CreateObject ( "WScript.Shell" ) exitCode = WshShell . Run ( "cmd /c "" python job.py >> job.log 2>&1 "" " , 0 , True ) WScript . Quit ( exitCode ) Note the parentheses — required when you're taking a return value. After fixing this across 17 launchers, one task showed a non-zero result for the first time in its life . It had been failing for weeks. 2. The last line of your batch file overwrites the exit code Fixed the launcher, still got false greens. The next layer down was a .cmd shim: node pipeline .js >> run .log 2 >& 1 echo [ done ] exit code %errorlevel% >> run .log That echo is the last command, echo always succeeds, so the batch file returns its exit code — zero — regardless of wh