ChatGPT/Codex Windows Desktop App — Stuck in "Complete Windows Setup" one-time permission loop

Product: ChatGPT desktop app for Windows (bundles OpenAI Codex agent)
Package: OpenAI.Codex, version 26.803.5235.0, x64, Microsoft Store MSIX distribution (official chatgpt.com/download also redirects to this same Store package — no alternate installer channel exists)
OS: Windows 10 Home, build 19045

Symptom: On first launch, the "完成 Windows 設定 / Complete Windows Setup" screen shows a UAC-style consent dialog captioned "ChatGPT 需要一次性權限，才能在您的電腦上運作" (ChatGPT needs one-time permission to run on your device). Clicking either button, or "以有限存取權繼續" (Continue with limited access), always results in "Windows 安裝未完成" (Windows setup not completed) and loops back to the same screen. This happens regardless of choice, and is 100% reproducible across a clean reinstall.

Steps already tried, all failed to resolve:

1. Repair via Settings > Apps > Advanced options
2. Reset via same
3. Launched app as Administrator
4. Fully removed (Remove-AppxPackage) and reinstalled clean from Microsoft Store — identical result
5. Confirmed Windows AppReadiness service (handles first-run Store-app setup) was Stopped; manually started it (Running) — no change
6. Confirmed clicking the retry button generates zero entries in Microsoft-Windows-AppReadiness/Admin or Microsoft-Windows-AppXDeployment/Operational event logs — indicates the loop is entirely inside the app's own UI/renderer code, not an actual OS-level permission call
7. Confirmed network connectivity to OpenAI endpoints is fine (TLS handshake succeeds, TCP established)
8. No crash/error entries in Windows Event Viewer Application log for ChatGPT.exe
9. Device is not domain/MDM-managed; Windows Defender real-time protection active, no blocks logged
10. Current Windows account has local Administrators membership (UAC Admin Approval Mode, standard filtered token — not a permissions-restricted account)

Question: What does this "one-time permission" step actually attempt internally (driver install? protocol handler registration? something else)? Is there a known workaround or a way to bypass/force-complete this first-run flow (e.g. a registry flag or local state file the app checks)?