Token Counts Are Not Model Lineage: A Frozen-Threshold Holdout Study of Black-Box LLM API Fingerprinting
A validity-gated result contract is introduced that distinguishes an observed dissimilarity from an uninformative measurement caused by missing usage data, rate limits, or endpoint policy, and validates token-count consistency as a fingerprint of a shared tokenization stack, but rejects its use as a standalone necessary test for model-family lineage.
Bolin Chen
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