Account-specific capacity errors across Codex models despite a fully available weekly allowance

Environment

• Subscription: ChatGPT Pro 20x
• Verified CLI version: codex-cli 0.153.4, bundled with the desktop app
• Minimal reproduction platform: macOS, Apple Silicon
• Models: gpt-6-astra, gpt-5.6-luna, both at low reasoning
• Latest verified reproduction: September 7, 2026, approximately 10:58–10:59 UTC+8

Problem

One of my Pro 20x accounts repeatedly receives:

Selected model is at capacity. Please try a different model.

A second account with the same subscription works normally under comparable conditions.

I have also observed this problem across Linux, macOS ARM64, and Windows 11, using Codex CLI, app-server, and the desktop app. Switching models or clients does not resolve it.

Minimal reproduction

With the affected account signed in, run the following using Codex CLI 0.153.4:

codex exec \
  --ignore-user-config \
  --ephemeral \
  --skip-git-repo-check \
  -C /tmp \
  -s read-only \
  -m gpt-6-astra \
  -c 'model_reasoning_effort="low"' \
  --json \
  'Reply with exactly OK. Do not use tools.'

Repeat with -m gpt-5.6-luna.

Both tests failed with:

{"type":"error","message":"Selected model is at capacity. Please try a different model."}
{"type":"turn.failed","error":{"message":"Selected model is at capacity. Please try a different model."}}

These were fresh temporary tasks with user configuration disabled, rather than continuations of long conversations.

Quota and authentication checks

Immediately before these tests, the affected account’s usage endpoint returned the following fields:

{
  "plan_type": "pro",
  "rate_limit": {
    "allowed": true,
    "limit_reached": false,
    "primary_window": {
      "used_percent": 0,
      "limit_window_seconds": 604800
    }
  }
}

The weekly allowance had just reset: 0% used, 100% remaining. The usage endpoint reported allowed: true and limit_reached: false, but both minimal requests still failed with the capacity error.

Local checks confirmed that the authentication file and token identity claims referred to the affected account, the access token had not expired, and no API key was configured.

Expected behavior

Ordinary requests should succeed when access and quota are available, or return an actionable explanation if an account-specific restriction applies.

Investigation request

Could the team correlate these failures with backend telemetry and check the affected account’s provisioning, routing, throttling, and quota accounting? The client-side evidence does not establish which of these is responsible.

Related: #41790. This report adds a same-subscription account comparison and a minimal reproduction with user configuration disabled and 100% of the weekly allowance remaining.

I can provide account details and diagnostic identifiers through a private support channel.

Start by running the supplied codex exec reproduction on the affected account and checking the usage endpoint fields described in the report. Compare the behavior with the working account and related issue #41790; this is complete only when the account-specific cause is identified and the client returns either a successful request or an actionable explanation.