Feature request: Usage/billing API for Max plan users

Feature Request

As a Max plan subscriber using Claude Code CLI,
I want to check my current billing cycle usage (messages remaining, cost breakdown) from the CLI or via API,
so that I can monitor my weekly/monthly usage without leaving the terminal.

Current Behavior

• There is no programmatic way to check Max plan usage
• Users must manually visit https://claude.ai/settings/billing in a browser
• The /cost command only shows the current session cost, not plan-level usage

Desired Behavior

• A CLI command (e.g., /usage or /billing) that shows:
• Current billing period
• Messages used / remaining
• Cost breakdown (if applicable)
• Alternatively, an API endpoint that returns this data

Context

For power users who spend most of their time in the terminal, having to switch to a browser to check usage is a friction point. This is especially relevant for Max 20 plan users who need to track their message budget.

Plan

Max 20