[BUG] Claude Opus 4.6 usage limit instantly maxed after 5-hour reset

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?

After waiting for the 5-hour session reset, Claude Opus 4.6 usage is instantly maxed out after only two prompts.
The reset appears to occur normally, but within ~2 minutes and two prompts:

The 5-hour session limit becomes fully used
Weekly usage jumps from ~40% to ~54%
Prompts were normal-sized (not unusually long or heavy)

This makes the quota unusable immediately after reset and seems inconsistent with expected token usage behavior.

What Should Happen?

After the 5-hour reset, usage should increase gradually based on prompt size and token consumption.
Two normal prompts should not fully exhaust the 5-hour limit or significantly jump weekly usage.

Error Messages/Logs

No explicit error message is shown.
The issue is observed via the usage meter:

5-hour usage instantly maxed
Weekly usage: 40% → 54% after two prompts

Steps to Reproduce

Use Claude with Opus 4.6
Wait until the 5-hour usage session resets
Send one normal prompt
Send a second normal prompt within ~2 minutes
Observe usage meter
5-hour session becomes fully used immediately
Weekly usage increases disproportionately

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Not sure — previously this behavior did not occur with earlier Opus sessions.

Claude Code Version

Latest (exact version not checked)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Occurred immediately after session reset
Only two prompts were sent
No long context or file uploads
Weekly usage increased unusually fast
Happens specifically when using Opus 4.6
May be related to incorrect token accounting or quota calculation