Feature request: Usage/spending API endpoint + status line integration

Summary

There's currently no programmatic way to check monthly Claude usage or spending. This makes it impossible to surface account-level usage data in tooling like the Claude Code status line.

Requested changes

1. A usage/spending API endpoint

Something like GET /v1/usage (or under the Console API) that returns current-period spend and quota, e.g.:

{
  "period": "2026-06",
  "spent_usd": 100.00,
  "limit_usd": 500.00,
  "credits_remaining_usd": 400.00
}

2. Claude Code status line integration

Once the data is available, expose it as a status line variable so users can display something like $100/$500 in their status bar — similar to how the current session token cost is already shown.

Use case

Users on team/enterprise plans with configured usage limits (e.g. extra usage allocated by a company admin) have no way to monitor how much of their monthly budget they've consumed without visiting the Console web UI. A queryable endpoint would unlock status line widgets, shell aliases, and other lightweight monitoring tools.

Current workaround

Manual check at console.anthropic.com → Usage tab.