Do LLMs Favor Their Providers? Measuring Vertical Integration Bias in Code Generation

Fuente: arXiv
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Auteurs principaux: Catal, Melih, Wolf, Alex, Matos, Tiago Ferreiro, Rani, Pooja, Gall, Harald
Format: Preprint
Publié: 2026
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author Catal, Melih
Wolf, Alex
Matos, Tiago Ferreiro
Rani, Pooja
Gall, Harald
author_facet Catal, Melih
Wolf, Alex
Matos, Tiago Ferreiro
Rani, Pooja
Gall, Harald
contents Large Language Models (LLMs) have become an integral part of software development, especially with the advent of agentic capabilities. Yet, many frontier LLMs are affiliated with specific providers. This raises the question of whether generated code favors the provider's own ecosystem over comparable alternatives, potentially constraining developers' choices and increasing dependence on a single provider. We define this behavior as Vertical Integration Bias (VIB) and introduce \textsc{VIBench}, a benchmark for measuring VIB in direct and agentic code generation across $20$ provider-selectable software-integration scenarios. Evaluating $10$ frontier provider-affiliated models against $3$ non-affiliated controls, we find positive VIB in direct generation, with six of ten affiliated models showing statistically significant effects up to $+18.8$ percentage points (pp). Agentic workflows further amplify VIB, reaching $+39.2$ pp. Moreover, early affiliated-ecosystem choices in agentic workflows can persist into conceptually decoupled downstream files, with persistence as high as $90.3\%$. These findings underscore the need to measure and account for VIB in code generation, especially as agentic capabilities become more prevalent.
format Preprint
id arxiv_https___arxiv_org_abs_2605_28515
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Do LLMs Favor Their Providers? Measuring Vertical Integration Bias in Code Generation
Catal, Melih
Wolf, Alex
Matos, Tiago Ferreiro
Rani, Pooja
Gall, Harald
Software Engineering
Artificial Intelligence
Large Language Models (LLMs) have become an integral part of software development, especially with the advent of agentic capabilities. Yet, many frontier LLMs are affiliated with specific providers. This raises the question of whether generated code favors the provider's own ecosystem over comparable alternatives, potentially constraining developers' choices and increasing dependence on a single provider. We define this behavior as Vertical Integration Bias (VIB) and introduce \textsc{VIBench}, a benchmark for measuring VIB in direct and agentic code generation across $20$ provider-selectable software-integration scenarios. Evaluating $10$ frontier provider-affiliated models against $3$ non-affiliated controls, we find positive VIB in direct generation, with six of ten affiliated models showing statistically significant effects up to $+18.8$ percentage points (pp). Agentic workflows further amplify VIB, reaching $+39.2$ pp. Moreover, early affiliated-ecosystem choices in agentic workflows can persist into conceptually decoupled downstream files, with persistence as high as $90.3\%$. These findings underscore the need to measure and account for VIB in code generation, especially as agentic capabilities become more prevalent.
title Do LLMs Favor Their Providers? Measuring Vertical Integration Bias in Code Generation
topic Software Engineering
Artificial Intelligence
url https://arxiv.org/abs/2605.28515