[BUG] System incorrectly downgraded Max Plan to Free after requesting a refund for unapplied usage credits

### Preflight Checklist

- [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) and this hasn't been reported yet
- [x] This is a single bug report (please file separate reports for different bugs)
- [x] I am using the latest version of Claude Code

### What's Wrong?

### Problem Description
I am completely unable to use Claude Code in my terminal due to a critical account and billing synchronization error on Anthropic's backend.

I recently purchased additional usage credits for the CLI, but they were never applied to my account balance. Since the credits did not appear after more than 20 hours, I requested a refund for them via the automated support system (Fin AI Agent)—specifically referencing the email "Your receipt from Anthropic, PBC #2193-1310-8018."

Immediately after requesting a refund for these missing credits, the system penalized me by incorrectly downgrading my entire account from the Max plan to the Free plan. This occurred despite the fact that I had paid for a full month of the Max plan just 15 days prior. The system essentially cancelled my active, paid 30-day subscription because I complained about a separate issue regarding the credit purchase.

### Detailed Timeline and Facts
- **August 15, 2026:** I paid for the Max plan subscription. The billing cycle was supposed to guarantee access for 30 days (until September 15, 2026).
- **August 31, 2026:** I purchased additional usage credits (R$ 50.00, R$ 20.00, and R$ 158.45) to use with Claude Code. All invoices appear as "Paid."
- **September 1, 2026:** The credits were never applied (the balance remained negative). I requested a refund for these unapplied credits via automated support.
- **September 1, 2026:** My account was abruptly and incorrectly downgraded from the Max plan to the Free plan, despite having 15 days remaining in my active paid month. - **Current Status:** I am on the Free plan; my paid Max plan has disappeared, the credits were not applied, and accessing `https://claude.ai/restricted` simply redirects to `https://claude.ai/new`, indicating there are no active bans—just a failed account state.

### Result
I missed the deadline for a job that would have earned me $400.

### Important note regarding potential duplicates (Do not auto-close)
Please do not automatically close this ticket as a duplicate. Although the underlying billing system failure is similar to that of the suggested cases, this is a distinct case involving a specific trigger for a plan downgrade: a refund request for **unapplied credits (credits paid for but never added to the account balance)** that resulted in the improper cancellation of a separately paid Max plan.

Related systemic billing failures exhibiting this exact pattern (for context):
- **Ticket #86503:** Credit dispute incorrectly cancelled an active, separately paid subscription.
- **Ticket #78577:** Automated bot denying refunds for unauthorized system upgrades based on flawed logic.
- **Ticket #67407:** Account plan downgrade due to a billing error.

[Invoice-EIABGYVN-0035.pdf](https://github.com/user-attachments/files/31737486/Invoice-EIABGYVN-0035.pdf)

Please escalate this case to a human agent or a backend engineer. The automated support cycle cannot correct this account-specific state desynchronization or the billing system logic failure.

### What Should Happen?

- A request for a refund of usage credits that—due to a technical failure—were not applied to the account balance must NOT result in the cancellation of a separate Max plan subscription that has already been paid for and still has 15 days of validity remaining.
- The Max plan subscription paid for on August 12 must be restored and remain active until September 12.
- Authentication via sockets and CLI must reflect the correct paid tier.

### Error Messages/Logs

```shell
There are no direct crash logs. The issue stems from a failure in the account synchronization and billing backend. The `/login` command works but incorrectly retrieves the "Free" plan status instead of my active "Max" plan. Furthermore, the `/usage-credits` command fails to display purchased credits, completely blocking the workflow I intended to carry out.
```

### Steps to Reproduce

1. Have an active Max plan subscription.
2. Purchase additional usage credits during a system outage (the credits are not applied to the balance).
3. Request a refund for the unapplied credits (credits that never reached the account balance) via automated email support.
4. Observe the system incorrectly cancel or downgrade the full Max subscription instead of simply processing the refund for the credits.
5. Log in to Claude Code using `/login` and notice that the Max plan is not recognized, blocking use of the CLI.

### Claude Model

None

### Is this a regression?

No, this never worked

### Last Working Version

_No response_

### Claude Code Version

It is not possible to verify the version via `claude --version` because this specific downgrade bug blocks the CLI with the error: "Your organization has disabled Claude subscription access...". I am using the latest version.

### Platform

Anthropic API

### Operating System

Windows

### Terminal/Shell

PowerShell

### Additional Information

[Invoice-EIABGYVN-0035.pdf](https://github.com/user-attachments/files/31737486/Invoice-EIABGYVN-0035.pdf)

The issue mentions the /login and /usage-credits CLI commands plus account plan state after a refund request, but no files, tests, or code entry points. First determine whether this belongs in the public Claude Code repo or an internal billing/account backend. Done would require restoring the account state and proving refunding unapplied credits cannot cancel an active Max plan.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.