Show HN: agent-usage-guard – a Claude Code mod to protect your usage window

agent-usage-guard is a Claude Code plugin designed to prevent runaway spending of your five-hour usage window by monitoring live usage metrics and blocking excessive subagent calls, context churn, and retry loops before they occur. The tool runs locally within Claude Code, prompts users for approval on risky operations, and provides transparency through usage reports while maintaining privacy by storing only counts and metrics, never prompt text or model outputs. The creator developed it after a single session accidentally spent 84M context tokens in ten minutes through 394 subagent calls, completely exhausting their usage window.