OpenAI OAuth account plan_type remains Plus after usage_limit_reached reports free

[XiaoYu994]

Summary

OpenAI OAuth accounts can still be shown as Plus in the admin account list even after the upstream OpenAI response reports plan_type: "free" in a usage_limit_reached 429 response.

This makes the displayed account plan stale/misleading: the account is handled by OpenAI as a Free account, while Sub2API still displays the cached credentials.plan_type as Plus.

Environment

• Repository: Wei-Shaw/sub2api
• Observed on commit: dbc8ae6
• Deployment: Docker image built from current main
• Account type: OpenAI OAuth

Reproduction

1. Have an OpenAI OAuth account whose local accounts.credentials.plan_type is cached as plus.
2. Run the admin account test endpoint, for example POST /api/v1/admin/accounts/{id}/test, after the upstream account has become Free or has exhausted its Free usage window.
3. OpenAI returns a 429 response like:

{
  "error": {
    "type": "usage_limit_reached",
    "message": "The usage limit has been reached",
    "plan_type": "free",
    "resets_at": 1778634027,
    "resets_in_seconds": 210842
  }
}

4. The account list still shows Plus.

Actual Behavior

• rate_limit_reset_at is updated correctly from resets_at.
• credentials.plan_type remains the previous cached value, for example plus.
• The frontend PlatformTypeBadge renders this stale planType and continues to show Plus.

Expected Behavior

When OpenAI returns error.plan_type in usage_limit_reached / related 429 responses, Sub2API should either:

• persist the observed value to accounts.credentials.plan_type, especially when it changes to free; or
• store/display an explicit observed/current plan state so the UI does not present stale cached subscription data as current.

Also, if subscription_expires_at is already in the past, the admin UI should probably avoid showing the cached Plus badge as a current plan unless a fresh account check confirms it.

Suspected Code Paths

• backend/internal/service/account_test_service.go
  • reconcileOpenAI429State parses/reset-limits the 429 state but does not update plan_type.
• backend/internal/service/ratelimit_service.go
  • parseOpenAIRateLimitResetTime parses reset fields from usage_limit_reached, but ignores error.plan_type.
• frontend/src/components/common/PlatformTypeBadge.vue
  • renders planType directly from cached account credentials without checking staleness or expiry.

Notes

This is visible when an account was previously cached as Plus but OpenAI now responds with plan_type: "free". In that state, routing/limits should follow the upstream response, while the admin UI still suggests the account is Plus.