[BUG] /usage statistics keep old account stats when you change accounts

Preflight Checklist

• [x] I have searched existing issues 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?

I switched from a personal account to an enterprise account today in the same Claude code filesystem. The usage stats history shows usage from two months ago, which is clearly from when I used my personal account.

For example, here are stats for the enterprise account that I started using today:
Sessions: 133 Longest session: 18d 14h 24m

What Should Happen?

Once I switch claude code should only show stats from the current login. Perhaps offer to look at historical data from the other login.

Error Messages/Logs

Steps to Reproduce

1. use claude code with a single-user account for a few days
2. exit session
3. start session in same directory context
4. /login to enterprise account
5. /usage -> stats
6. expected: almost empty, just the usage from step 4
7. actual: usage included data from account in step 1

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.145 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

IntelliJ IDEA terminal

Additional Information

_No response_