[Bug] ZCode 3.12.3 (Windows): Coding Plan shows "Not subscribed" after update despite active subscription

OS: Windows 11
ZCode Desktop version: 3.12.3 (auto-updated Sep 17, 2026)
Plan: Individual "Plus" Coding Plan (active before the update)

Symptom
After the 3.12.3 auto-update, ZCode stopped recognizing my active Coding Plan subscription. Main screen shows "No model available. Upgrade or set a custom model." Model settings > Z.ai provider shows "Coding Plan - Not subscribed, enabled after subscription", with Unlink available (so the account is still connected/linked to Z.ai - this isn't a login/session problem).

Already tried, no effect on either:

1. Full uninstall + reinstall of ZCode (reinstalls the same 3.12.3 - no older version cached to roll back to)
2. Full local app-data reset (cleared %APPDATA%\ZCode) + fresh login - account relinked successfully, but Coding Plan still shows "Not subscribed"

Since the account stays linked but entitlement isn't recognized even after a full local data wipe, this looks like a client-side entitlement/provider-registry read bug introduced in 3.12.3, not a session/cache issue - possibly the same class of bug as #695 (provider registry discarding config payloads due to a revision type mismatch).

Happy to provide logs/more detail if useful.

Reproduce the subscription recognition failure in ZCode Desktop 3.12.3 on Windows 11 after the update, reinstall, and %APPDATA%\ZCode reset. Compare the provider-registry behavior with the related discussion in #695 and inspect any available logs; done means the linked account recognizes the active Coding Plan instead of showing “Not subscribed.”