The runaway bill

Trace-detective lab (Module 7, L7.1): the 200-step survivor finished its task, then the invoice arrived. Meter a deterministic 214-turn run with a cost ledger (tokens x an illustration rate table, cached input at a tenth), attribute the bill to three turn ranges (a doom loop, compaction churn, an overflow paste) that cover at least 90 percent of it, and name the missing mechanism for each: a repetition guard, prefix discipline, overflow to disk. Bigger budgets, cheaper models and routing are graded and fail: priced on the same tier the waste is unchanged. In-memory only; no provider call or real prices.

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