Why does the Gemini app not use Compose?

In the rapidly evolving landscape of Android development, the introduction of Jetpack Compose marked a paradigm shift in how developers build user interfaces. It promised a declarative, Kotlin-first approach that streamlined UI creation, reduced boilerplate code, and offered a more intuitive way to manage state. As the official modern toolkit for building native UI, Compose has been widely adopted across the Android ecosystem. However, a recent observation by a user on a popular forum sparked a debate within the developer community: the Gemini app, a major application released in 2024, appears to be built entirely using the traditional XML/View system. This observation, made using the “Show Layout Bounds” developer option, presents a fascinating case study. It raises a critical question: why would a cutting-edge application, backed by a tech giant known for innovation, choose a legacy UI framework over the modern standard? We will delve into the multifaceted reasons behind this strategic decision, exploring the technical, business, and performance considerations that likely influenced the architecture of the Gemini app.

Understanding the Fundamental Differences: XML/View vs. Jetpack Compose

Before we can analyze the decision-making process behind the Gemini app’s architecture, it is crucial to establish a clear understanding of the two competing UI paradigms. The traditional Android UI toolkit, based on XML layouts and the View system, has been the foundation of Android development since its inception. This system is imperative; developers explicitly define the hierarchy of UI elements in XML files and manipulate these views programmatically in the host Activity or Fragment. State changes are managed by manually traversing the view tree and updating individual properties. While robust and mature, this approach is often criticized for its verbosity, complex lifecycle management, and the difficulty of building dynamic, interactive interfaces.

In stark contrast, Jetpack Compose offers a declarative framework built entirely in Kotlin. Instead of describing how to draw the UI step-by-step, developers declare what the UI should look like for a given state. The framework handles the underlying rendering, state tracking, and updates automatically. Compose rethinks the UI composition, breaking down interfaces into small, reusable functions called composables. This paradigm simplifies code, enhances readability, and provides powerful tools for managing state, theming, and animation. The Android community has largely embraced Compose as the future, with Google actively encouraging its adoption through documentation, sample projects, and a continuous stream of feature updates. Therefore, a major application eschewing Compose in favor of the older system is a deviation from the expected trajectory, compelling us to look deeper than surface-level trends.

The Immense Scale and Legacy Codebase of a Titan

One of the most significant factors that likely prevented the adoption of Jetpack Compose for the Gemini app is the sheer scale and historical depth of its underlying codebase. The Gemini app is not a fresh start; it is the successor to and an evolution of previous flagship applications like Google Assistant. This lineage carries with it a massive, monolithic codebase written over a decade, consisting of millions of lines of code, thousands of XML layouts, and countless custom Views and Fragments. Rewriting such a colossal architecture from scratch is not merely a matter of preference; it is a monumental engineering undertaking fraught with risk.

A complete migration to Jetpack Compose would require a complete redesign of the user interface, a re-architecture of the navigation logic, and a rewrite of state management at the application level. For a product used by billions of users worldwide, this presents several critical challenges:

• Resource Allocation: Diverting a massive team of highly skilled engineers to focus solely on a UI framework migration would mean pulling them away from developing new features, improving AI models, and fixing critical bugs. The opportunity cost is substantial.
• Parity and Regression: The primary goal would be to achieve 1:1 feature parity with the existing app. This is an incredibly difficult task, as the legacy View system has quirks and behaviors accumulated over the years that are not trivial to replicate perfectly in Compose. The risk of introducing subtle UI bugs, visual regressions, or behavioral changes that impact user experience is unacceptably high.
• Timeline and Complexity: A project of this magnitude could take years to complete. By the time the migration is finished, the framework itself would have likely evolved, potentially requiring further updates and refactoring.

Given these factors, it is often more pragmatic for large organizations to maintain and extend a stable, well-understood legacy system rather than undertaking a high-risk, high-cost rewrite. The decision to stick with XML/Views is not a rejection of Compose’s merits but a calculated business decision to prioritize stability and feature development over a complete architectural overhaul.

The Critical Role of Performance and Predictability

While Jetpack Compose has made tremendous strides in performance, the traditional View system still holds a distinct advantage in specific scenarios, particularly regarding raw performance and predictability. For an application as complex as Gemini, which integrates deeply with the operating system and handles real-time, responsive interactions, performance is non-negotiable. The View system, having been optimized for over a decade, offers a highly predictable performance profile. Its layout pass, rendering pipeline, and recycling mechanisms are mature and well-understood.

We can identify several performance-related reasons why the Gemini team might have preferred the View system:

Predictable Layout Passes

The View system’s layout hierarchy is explicit. When a layout is measured and drawn, the process follows a deterministic path. While complex nesting can lead to performance issues, the behavior is predictable and can be optimized with tools like ConstraintLayout. In contrast, Compose’s recomposition model, while efficient, can sometimes lead to unexpected performance bottlenecks if not managed carefully. Unstable composable parameters or poorly defined state can trigger excessive recompositions, leading to jank. For a UI that must be pixel-perfect and frame-rate-stable at all times, the predictable nature of the View system can be a safer bet.

Memory Footprint

Jetpack Compose introduces its own runtime and memory management overhead due to its use of Kotlin compiler plugins and a distinct composition model. For a large-scale application, this additional memory footprint could be significant. The View system, while not without its own overhead, is more lightweight in certain contexts, especially for static or less interactive screens. In a resource-constrained environment, every megabyte of RAM counts, and maintaining a smaller memory profile is a key performance metric.

Maturity of Custom Views and Hardware Acceleration

The Gemini app undoubtedly relies on numerous highly customized, complex UI components. Many of these custom Views have been developed and refined over years, leveraging low-level drawing commands with Canvas and direct manipulation of properties. Replicating this level of performance and functionality in Compose using DrawModifier or custom AndroidView wrappers can be complex and may not achieve the same level of optimization. Furthermore, the hardware acceleration pipeline for the View system is exceptionally mature and optimized across a vast range of devices, from low-end to high-end, ensuring consistent performance for all users.

UI Consistency and Unified Rendering Across Platforms

A key requirement for a global product like Gemini is maintaining strict UI consistency across different platforms and form factors. The Gemini experience is not limited to a single Android app; it spans web, iOS, and potentially desktop environments. While Compose Multiplatform is an emerging technology, it is not yet mature enough for a mission-critical application like Gemini that demands absolute fidelity across all target platforms.

The traditional XML/View system provides a stable, well-defined rendering baseline. To ensure a unified look and feel, large organizations often employ design systems that are implemented natively on each platform. The Android implementation of this design system, built with Views, can be meticulously crafted to match the iOS and web versions pixel-for-pixel. This native implementation guarantees that UI elements like buttons, cards, and navigation components behave identically across the ecosystem.

Adopting a relatively new framework like Compose could introduce subtle rendering differences, especially when combined with other modern Android libraries. The goal of a global brand is to eliminate these inconsistencies, and a mature, battle-tested framework provides a higher degree of confidence in achieving this visual uniformity. Therefore, the choice to use Views can be interpreted as a commitment to a stable, consistent visual identity that is aligned with the broader cross-platform strategy.

Integration with Existing Ecosystem and Build Systems

The integration of a new UI framework into a massive, complex build system is a challenge in itself. Large applications like Gemini often utilize intricate Gradle build configurations, custom build plugins, and a deep dependency graph. Introducing Jetpack Compose requires updating the Kotlin version, integrating specific compiler plugins, and potentially refactoring modules to be compatible with the new paradigm.

For an app with a large number of dynamic feature modules and a complex dependency management strategy, this integration can be fraught with challenges. The Compose compiler and runtime add to the build time, which is a critical metric for developer productivity. In a large engineering organization, even a minor increase in build time can aggregate into significant lost productivity across the entire team. The View system, being a stable part of the Android SDK for over a decade, integrates seamlessly with existing build tools and does not carry the same risk of disrupting the delicate balance of a large-scale CI/CD pipeline. The path of least resistance is often to stick with the technology that has proven to be stable and scalable within the existing infrastructure.

Developer Experience and Team Expertise

A successful application is built by a team of experts. The engineers working on the Gemini app are likely world-class developers with deep knowledge of the Android platform, its intricacies, and its performance characteristics. This expertise is heavily rooted in the XML/View system. While learning Compose is achievable, transitioning an entire large team to a new paradigm requires significant investment in training and a period of adjustment.

During this transition, productivity can temporarily decrease as developers navigate the learning curve, which involves understanding new concepts like recomposition, state hoisting, and custom layout logic. For a fast-paced product like Gemini, where new features and AI capabilities are being rolled out frequently, halting or slowing down development to retrain the entire team may not be feasible. The existing team’s proficiency with the View system allows them to build, debug, and optimize the UI efficiently and with a high degree of confidence. This expertise translates directly into a more stable product and faster iteration cycles.

Furthermore, debugging and tooling for the View system are incredibly mature. The layout inspector, profiler, and other developer tools have been refined over many years to provide deep insights into UI performance. While Compose tooling is improving rapidly, the mature ecosystem surrounding the View system remains a powerful asset for large-scale development.

The Strategic Pragmatism of Sticking with a Proven Technology

Ultimately, the decision for a product of Gemini’s magnitude to not use Jetpack Compose is a reflection of a core engineering principle: pragmatism over novelty. Technology choices for large-scale applications are not made in a vacuum; they are weighed against a backdrop of business objectives, resource constraints, risk assessment, and long-term maintainability.

While Jetpack Compose is undeniably the future of Android development and is the recommended choice for new projects, it does not automatically invalidate the past for established, massive applications. The View system remains a powerful, mature, and capable framework. For the Gemini app, the costs and risks associated with a full migration appear to outweigh the benefits at this stage in its lifecycle. The stability, performance predictability, and existing engineering investment in the View system make it a logical and responsible choice.

This decision does not signify a lack of innovation. Instead, it highlights a strategic focus on what truly matters for the product’s success: delivering a reliable, high-performance, and consistent user experience while continuously pushing the boundaries of its core AI capabilities. The choice to stick with a proven technology is a testament to a mature engineering culture that prioritizes user value above all else.

The Future Outlook: A Potential Hybrid Approach

It is important to note that choosing not to use Compose for the entire app does not mean it is excluded entirely. A common strategy for large applications undergoing modernization is the adoption of a hybrid approach. In this model, the core of the application remains built on the stable View system, but new features, screens, or complex interactive components are developed using Jetpack Compose. This allows teams to leverage the benefits of Compose for new development without the risk of rewriting the entire application.

The AndroidView composable in Jetpack Compose provides a seamless bridge to embed traditional Views within a Compose tree, and conversely, the ComposeView allows embedding Compose content within a Fragment or Activity. This interoperability is a key feature of Compose, designed explicitly for this kind of gradual migration strategy.

We might see the Gemini app slowly incorporating Compose in specific areas. For instance, a new settings screen, a complex onboarding flow, or a feature-rich chat interface could be built with Compose, allowing the team to gain experience and confidence in the framework while shipping new value to users. Over time, this could lead to a more comprehensive adoption of Compose, but it will be a measured and incremental process, not a big-bang replacement.

Conclusion: A Deliberate Engineering Decision

The observation that the Gemini app uses the XML/View system is a window into the complex reality of software engineering at a massive scale. It is not an indication of technological stagnation but rather a deliberate and well-reasoned architectural choice. The decision is rooted in the immense challenges of migrating a legacy codebase, the critical need for performance and predictability, the importance of cross-platform consistency, and the practical realities of managing a large engineering team and complex build systems.

We have explored the deep-seated reasons that favor the stability and maturity of the View system for an application of this caliber. While Jetpack Compose represents the future of Android UI development, its adoption in legacy systems must be strategic and incremental. The Gemini app serves as a powerful case study, reminding us that the best technology choice is not always the newest one, but the one that best aligns with the product’s goals, constraints, and the user’s need for a flawless experience. As the Android ecosystem continues to evolve, the balance between leveraging mature, stable technologies and embracing modern innovations will remain a central theme in building the next generation of world-class applications.