[Feature Request] Expose API usage limits and rate-limit reset timer to Claude Code

Bug Description
Title: Expose usage limits and rate-limit reset timer to Claude Code

Summary
Claude Code currently has no visibility into the user's remaining message quota
or the countdown timer until the limit resets. This makes it impossible for
Claude Code to self-manage session pacing, warn the user proactively, or
gracefully pause autonomous tasks before hitting a hard wall.

Use Case
Power users running autonomous, long-running agentic tasks (multi-step pipelines,
background workers, overnight jobs) are blindsided when Claude Code hits a usage
limit mid-task. There is no warning, no graceful shutdown, no ETA for resumption.

Proposed Solution
Expose a read-only API or environment variable accessible within a Claude Code
session, e.g.:

• CLAUDE_USAGE_REMAINING (integer: messages or tokens left in current window)
• CLAUDE_LIMIT_RESET_AT (ISO 8601 timestamp: when the limit resets)

Alternatively, surface this in the Claude Code status bar / session header.

Expected Benefit

• Claude Code can warn the user before hitting the limit
• Autonomous agents can pause gracefully and resume after reset
• Reduces lost work and frustration for agentic workflows

Environment Info

• Platform: darwin
• Terminal: Apple_Terminal
• Version: 2.1.77
• Feedback ID: bbd23a64-b4c3-4930-b998-e80359e927d1

Errors

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