Add rate limit data to statusline JSON input

Feature Request

Add plan rate limit information to the statusline command's JSON input.

Problem

The statusline script receives a fixed JSON input that includes context_window data (per-conversation context usage), but does not include plan-level rate limit information (the 5-hour rolling window usage).

This data is available internally — the /usage command displays it:

Current session
██████████████████████████████                 50% used
Resets 6:59pm (Europe/Paris)

However, there is no way to access this from the statusline script, hooks, or any external mechanism.

Proposed Solution

Add a rate_limit (or plan_usage) object to the statusline JSON input:

{
  "rate_limit": {
    "used_percentage": 50,
    "remaining_percentage": 50,
    "tokens_limit": 1000000,
    "tokens_remaining": 500000,
    "reset_at": "2026-02-11T17:59:00Z"
  }
}

These values come from the Anthropic API response headers that Claude Code already receives:

• anthropic-ratelimit-tokens-limit
• anthropic-ratelimit-tokens-remaining
• anthropic-ratelimit-tokens-reset

Why

Users who customize their statusline want to monitor their plan usage at a glance — especially on Max plans where the 5-hour window matters. Currently, the only way to check is to run /usage manually or visit https://claude.ai/settings/usage.

Current Workarounds Explored (none viable)

• Hooks (PostToolUse, etc.): don't expose API response headers
• Transcript/debug logs: don't contain rate limit headers
• ccusage blocks: estimates synthetic 5h blocks that don't match the actual API rate limit window
• OAuth token + direct API call: token is in macOS Keychain, not easily accessible from scripts
• Proxy via ANTHROPIC_BASE_URL: fragile and complex

Environment

• Claude Code v2.1.39
• macOS, Max $100/month plan