Sub-agents burning your Claude Code 5-hour window? Check their 5-minute prompt cache

A developer found that sub-agents were rapidly consuming their Claude Code 5-hour window, often within an hour or two. The issue was traced to the sub-agents' 5-minute prompt cache. After implementing a one-line fix, the quota usage for four sub-agents dropped significantly, from 100% to 22%. This fix allowed sub-agents to run for extended periods with minimal re-writes and reduced token consumption, demonstrating the importance of optimizing cache usage.