[2604.09360] LLM-Rosetta: A Hub-and-Spoke Intermediate Representation for Cross-Provider LLM API Translation

Computer Science > Software Engineering arXiv:2604.09360 (cs) [Submitted on 10 Apr 2026] Title:LLM-Rosetta: A Hub-and-Spoke Intermediate Representation for Cross-Provider LLM API Translation Authors:Peng Ding View a PDF of the paper titled LLM-Rosetta: A Hub-and-Spoke Intermediate Representation for Cross-Provider LLM API Translation, by Peng Ding View PDF HTML (experimental) Abstract:The rapid proliferation of Large Language Model (LLM) providers--each exposing proprietary API formats--has created a fragmented ecosystem where applications become tightly coupled to individual vendors. Switching or bridging providers requires $O(N^2)$ bilateral adapters, impeding portability and multi-provider architectures. We observe that despite substantial syntactic divergence, the major LLM APIs share a common semantic core: the practical challenge is the combinatorial surface of syntactic variations, not deep semantic incompatibility. Based on this finding, we present LLM-Rosetta, an open-source translation framework built on a hub-and-spoke Intermediate Representation (IR) that captures the shared semantic core--messages, content parts, tool calls, reasoning traces, and generation controls--in a 9-type content model and 10-type stream event schema. A modular Ops-composition converter architecture enables each API standard to be added independently. LLM-Rosetta supports bidirectional conversion (provider-to-IR-to-provider) for both request and response payloads, including chunk-level ...