--- title: How Horizontal Clean Architecture Created a Room... description: When splitting an Android project into feature modules, a dependency cycle emerged from Room's requirement to reference entity types at compile time. The... canonical: https://daily.dev/posts/how-horizontal-clean-architecture-created-a-room-dependency-problem-mtlowwntj twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: How Horizontal Clean Architecture Created a Room Dependency Problem | daily.dev og:description: When splitting an Android project into feature modules, a dependency cycle emerged from Room's requirement to reference entity types at compile time. The... og:url: https://daily.dev/posts/how-horizontal-clean-architecture-created-a-room-dependency-problem-mtlowwntj og:image: https://api.daily.dev/og/posts/mTLOwWNTJ.png og:image:alt: How Horizontal Clean Architecture Created a Room Dependency Problem og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # How Horizontal Clean Architecture Created a Room Dependency Problem **[Medium](https://daily.dev/sources/medium_js)** · 9 min read · 0 upvotes · 0 comments ## Summary When splitting an Android project into feature modules, a dependency cycle emerged from Room's requirement to reference entity types at compile time. The author's horizontal Clean Architecture (presentation/domain/data layers) didn't clearly define who owned the database schema. The solution was introducing a dedicated `local` module per feature to hold Room entities and DAOs, breaking the cycle without merging everything into a shared core-database module. Architecture tests were added to enforce the new boundaries. The post also covers why a separate Paging abstraction was collapsed back into the feature implementation since it had no real second consumer. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Building a Modularized Android App: A Practical Guide to Clean Architecture in 2026](https://daily.dev/posts/building-a-modularized-android-app-a-practical-guide-to-clean-architecture-in-2026-kseskxqoz) · Medium · 0 upvotes · 0 comments - [Android Modularization That Holds Up: 5 Lessons for Large Codebases](https://daily.dev/posts/android-modularization-that-holds-up-5-lessons-for-large-codebases-1tagym5g1) · ProAndroidDev · 0 upvotes · 0 comments - [MVVM \+ Clean Architecture in Android: The Folder Structure That Scales](https://daily.dev/posts/mvvm-clean-architecture-in-android-the-folder-structure-that-scales-9nvzttmkb) · Medium · 0 upvotes · 0 comments - [Feature Modularization in Flutter: How to Combine Clean Architecture and Domain-Driven Design for Self-Contained, Scalable Features](https://daily.dev/posts/feature-modularization-in-flutter-how-to-combine-clean-architecture-and-domain-driven-design-for-se-av2mxrlbi) · freeCodeCamp · 1 upvotes · 0 comments - [Beyond CLEAN and MVP: Architecting an Offline-first Reactive Data Layer in Android](https://daily.dev/posts/beyond-clean-and-mvp-architecting-an-offline-first-reactive-data-layer-in-android-owjsx1xte) · InfoQ · 0 upvotes · 0 comments --- Tags: [#architecture](https://daily.dev/tags/architecture), [#android](https://daily.dev/tags/android) [View this post on daily.dev](https://daily.dev/posts/how-horizontal-clean-architecture-created-a-room-dependency-problem-mtlowwntj) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"How Horizontal Clean Architecture Created a Room Dependency Problem","url":"https://daily.dev/posts/how-horizontal-clean-architecture-created-a-room-dependency-problem-mtlowwntj","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/how-horizontal-clean-architecture-created-a-room-dependency-problem-mtlowwntj"},"datePublished":"2026-07-23T19:21:46.011Z","dateModified":"2026-07-23T19:36:42.058Z","description":"When splitting an Android project into feature modules, a dependency cycle emerged from Room's requirement to reference entity types at compile time. 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