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[Bug][2.36.0][Codex App] Plus account loses GPT-5.6 models; downgrade to 2.35.0 restores them #3022

Description

@h31105

Client or integration

Codex App

Area

Authentication / entitlement / model catalog

Summary

After upgrading OpenCodex from 2.35.0 to 2.36.0, a ChatGPT Plus account can no longer use the GPT-5.6 family in Codex.

Downgrading the same OpenCodex installation back to 2.35.0 immediately restores GPT-5.6 availability for the same Plus account.

Affected models:

  • gpt-5.6-sol
  • gpt-5.6-terra
  • gpt-5.6-luna

This looks like a 2.36.0 regression in the entitlement/catalog synchronization path rather than an actual account entitlement change, because the result is reproducible across the version boundary with the same account.

Reproduction

  1. Sign in to Codex with a ChatGPT Plus account that can use GPT-5.6 under OpenCodex 2.35.0.
  2. Confirm GPT-5.6 models are available/usable.
  3. Upgrade OpenCodex to 2.36.0.
  4. Restart/reload Codex so the model catalog is refreshed.
  5. Observe that the GPT-5.6 family is no longer usable / the model picker changes.
  6. Downgrade OpenCodex back to 2.35.0:
npm install -g @bitkyc08/opencodex@2.35.0
  1. Restart Codex.
  2. GPT-5.6 availability returns for the same Plus account.

Controlled A/B result

OpenCodex version ChatGPT plan GPT-5.6
2.35.0 Plus Works
2.36.0 Plus Does not work
2.35.0 (downgrade) Plus Works again

Version

Regression observed in 2.36.0. Control version: 2.35.0.

Operating system

macOS 26.6.2

Provider and model

OpenAI Codex login / ChatGPT Plus:

  • gpt-5.6-sol
  • gpt-5.6-terra
  • gpt-5.6-luna

Suspected area

2.36.0 includes changes around requesting/reconciling the upstream entitlement roster using the real Codex client version. The clean 2.35 → 2.36 → 2.35 A/B suggests that the refreshed entitlement/catalog logic may be producing a false negative for an entitled Plus account.

Related issue #2886 reports a similar false-negative catalog projection on an earlier version, but this report specifically captures a 2.36.0 regression where 2.35.0 works for the same account and downgrading restores GPT-5.6.

Expected behavior

An entitled ChatGPT Plus account that can use GPT-5.6 on 2.35.0 should retain the same GPT-5.6 models after upgrading to 2.36.0. A missing/stale/incorrect entitlement roster should not incorrectly remove or reject models the account is actually entitled to use.

Checks

  • Searched existing issues for GPT-5.6 / entitlement / 2.36.0 reports.
  • Reproduced across an upgrade and downgrade boundary.
  • No credentials, tokens, email addresses, or account identifiers included.

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    bugSomething isn't workingcatalogModel catalog, slugs, visibility, routed entriesinstallInstallation or packaginglanded-via-maintainerOriginal PR closed after landing via a maintainer merge train

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