`estimateCost` used `inputTokens` and `outputTokens` without validation.
A negative count yielded a negative cost, and a non-finite one yielded
NaN. That matters here specifically because this module backs the
cost-aware-llm-pipeline budget skill: `NaN > budget` is false, so a
corrupt token count silently passes the budget check it exists to
enforce. It now throws a RangeError naming the offending field.
The unknown-model fallback to sonnet rates deliberately stays fail-open:
that degrades an estimate, whereas these inputs corrupt one.
Separately, the estimator prices Fable and Mythos at $10/$50 per million
tokens, but all three pricing tables (the skill and its ja-JP and zh-CN
translations) listed only Haiku, Sonnet, and Opus, so a reader could not
budget for two supported model families. Added the missing row to each.
16 of the new assertions fail against the previous behaviour (23 passed,
16 failed) and all pass with the guard (39 passed).
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KV43bDJpgyMPovT2CHAoba
