OLD design: a single 'Check Machine Number' scheduled task ran as the
logged-in user (BUILTIN\Users, Limited) on AtLogOn. It both showed the
InputBox AND tried to update HKLM\SOFTWARE\WOW6432Node\GE Aircraft
Engines\DNC\General + C:\ProgramData\UDC\udc_settings.json. To make
those non-admin writes possible, 02-MachineNumberACLs.ps1 pre-granted
BUILTIN\Users SetValue + Modify on those targets during imaging.
Three problems with that:
1. SECURITY: any logged-in user could overwrite the machine-identity
reg key.
2. FRAGILE: ACL grants raced with eDNC install timing on some bays
(eDNC reg key didn't exist yet when 02-MachineNumberACLs ran;
OpenSubKey returned null, ACL silently skipped, Check-MachineNumber
later failed with PermissionDenied).
3. SILENT-SUCCESS BUG: Update-MachineNumber's Set-ItemProperty calls
lacked -ErrorAction Stop. PermissionDenied is a non-terminating
error in PS5.1, so the try/catch never fired. The script set
$out.EdncUpdated=$true anyway and the dialog reported success
while the reg value stayed at 9999. WJF capture log on FGY07FZ3
shows this exact pattern.
NEW design - two scheduled tasks split by responsibility:
- "Prompt Machine Number" : AtLogOn trigger, BUILTIN\Users (Limited).
Reads current values (read-only). If 9999, shows InputBox. Writes
typed number to C:\Logs\SFLD\machine-number-request.txt. Triggers
SYSTEM Apply via schtasks /run. Polls for result JSON (60s timeout).
Shows result MessageBox with TopMost so it isn't hidden behind
other windows.
- "Apply Machine Number" : on-demand, SYSTEM (Highest). Reads the
request file, calls Update-MachineNumber (full HKLM + ProgramData
access from SYSTEM context). Pulls per-machine NTLARS .reg + UDC
settings JSON + UDC live data from the SFLD share if site-config
has share paths. Writes result JSON. Removes request file.
Unregisters the Prompt task on full success (Prompt itself can't
self-unregister - Limited users can't delete a SYSTEM-owned task).
- Default task SDDL only allows Admins + SYSTEM to read/run a
SYSTEM-owned task. Added BUILTIN\Users GR+GX ACE via COM
SetSecurityDescriptor so the Limited Prompt task can schtasks /run
Apply on demand. They can read + execute it; not modify or delete.
- Update-MachineNumber.ps1 writes now have -ErrorAction Stop so
PermissionDenied actually fires the catch block instead of being
swallowed.
- 02-MachineNumberACLs.ps1 gutted to a no-op (left in place for
Stage-Dispatcher discovery; no longer grants the ACLs). Old bays'
existing grants are harmless since SYSTEM ignores them.
- Register-CheckMachineNumberTask.ps1 now installs both tasks AND
unregisters the legacy 'Check Machine Number' task name on
re-imaging. Run-ShopfloorSetup.ps1's $skipInBaseline list now
includes Prompt-MachineNumber.ps1 + Apply-MachineNumber.ps1 so
they aren't auto-run during the baseline pass (only via the
scheduled tasks).
Smoke tested end-to-end on win11 VM with ShopFloor (Limited) logging in
interactively: AtLogOn trigger fired Prompt, dialog rendered, tech
typed 7777, schtasks /run succeeded (the SDDL fix lets Limited users
trigger SYSTEM tasks), Apply ran as SYSTEM, eDNC reg + machine-number.txt
both updated to 7777, result MessageBox shown, Prompt task auto-
unregistered by Apply's cleanup step. No ACL grants needed on any user.
Apply also re-tested with -ErrorAction Stop confirming non-terminating
PermissionDenied now properly throws into the catch + populates Errors[]
+ flips $out.EdncUpdated to false - so any future write failures will
report honestly instead of silently claiming success.
If a bay is imaged with the 9999 placeholder (tech leaves the WinPE
prompt blank or types 9999), the lockdown+auto-login chain ends up at
the ShopFloor user with no real machine number. We had Check-MachineNumber.ps1
written - InputBox + Update-MachineNumber pulls per-machine NTLARS .reg
+ udc_settings_<N>.json from the SFLD share - but it only got registered
when a tech manually ran Configure-PC + toggled item 6. Fresh 9999 bays
never got the prompt, leaving the bay stuck on placeholder values until
someone noticed.
New Register-CheckMachineNumberTask.ps1 auto-registers the logon task
at imaging time. Gated on C:\Enrollment\machine-number.txt == 9999;
bays imaged with a real number never get the task (and any stale task
from a prior 9999-imaging on the same disk is cleaned up).
Wired into Run-ShopfloorSetup.ps1 right after the S: drive logon mapper
register. Skipped for self-contained types (display kiosks have no
machine number).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
