Verify API–Interface Checkpoint Equivalence

Verify whether the matched API and chatbot-interface identifiers for ChatGPT, Claude, and Gemini correspond to the same underlying model checkpoints, so that observed API–interface benchmark gaps can be distinguished from differences caused by serving different model variants.

Background

The audit matches each deployed chatbot interface with the closest documented API identifier, but commercial providers generally do not disclose the exact checkpoint used for interface responses. Consequently, the reported comparisons may conflate access-surface effects with differences in the underlying models served through the two access paths.

Resolving this uncertainty would enable stronger causal interpretation of API–interface benchmark differences and clarify whether the observed context-validity gap arises from deployment layers, model variants, or both.

References

First, we cannot verify that matched API and interface identifiers always correspond to the same underlying checkpoint; if providers serve different variants across surfaces, some of the observed gap may reflect model differences rather than interface-layer effects.

— API Benchmark Scores Do Not Reliably Transfer to Chatbot Interfaces  (2609.08861 - Wang et al., 8 Sep 2026) in Section 7, Limitations

Without the ability to intervene at specific layers, researchers cannot determine whether an observed behavioral shift stems from a new model checkpoint, revised system instructions, changes to other components, or interactions among them.

— API Benchmark Scores Do Not Reliably Transfer to Chatbot Interfaces  (2609.08861 - Wang et al., 8 Sep 2026) in Section 6.2, “Auditing the Middle Layers Requires More Than Current API Access”