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 shipping Workers logs to R2 via Logpush and querying with DuckDB:
worker_name,
COUNT(*) as call_count,
