60% of My $312 Anthropic Bill Came From One Silent Loop — Here's How I Found It (opens in new tab)

Last month's Anthropic invoice: $312. Sixty percent of it traced back to a single retry pattern I couldn't see anywhere in my normal logs. The agent was failing on tool calls, then re-entering the loop with the full context intact — 18K input tokens per invocation on a task that needs 3-4K. Claude Code's UI looked fine. Workers logs showed 200s. D1 writes were clean. The billing dashboard just said "tokens used" with no breakdown by worker or call chain. I found the culprit only after shippin...