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Šimon Rozsíval

PROFILE

Šimon Rozsíval

Simon Rozsival engineered robust cross-platform runtime and UI infrastructure in the dotnet/android and dotnet/maui repositories, focusing on seamless .NET and Java interoperability, data binding reliability, and performance optimization. He delivered features such as a managed marshal method lookup for Xamarin.Android, a cross-runtime GC bridge, and a trimmable Java interoperability scanner, using C#, Java, and MSBuild. Simon refactored core subsystems like color parsing and type mapping, improved certificate handling, and enhanced CI/CD pipelines. His work addressed complex runtime edge cases, reduced memory leaks, and strengthened test coverage, demonstrating deep technical understanding and a disciplined, maintainable approach to software development.

Overall Statistics

Feature vs Bugs

67%Features

Repository Contributions

38Total
Bugs
11
Commits
38
Features
22
Lines of code
12,027
Activity Months14

Work History

February 2026

4 Commits • 2 Features

Feb 1, 2026

February 2026 monthly summary highlighting key features delivered, major bugs fixed, and impact across Maui and Android repos. Focused on delivering business value and technical achievements with concrete deliverables and future-oriented groundwork.

January 2026

6 Commits • 3 Features

Jan 1, 2026

January 2026 highlights across dotnet/maui and dotnet/android focused on stability, binding reliability, and cross-repo development efficiency. Delivered critical Maui fixes to reduce UI hangs and improve XAML binding, while strengthening Android/CoreCLR integration for better crash reporting and debugging. Updated CI/CD to the .NET 11 branch for forward compatibility and governance updates to streamline code reviews. Result: more responsive UIs, robust style binding with source-generated properties, clearer crash diagnostics, faster onboarding to new SDKs, and enhanced review processes.

November 2025

6 Commits • 3 Features

Nov 1, 2025

November 2025: Delivered tangible business value and improved developer experience across Maui and runtime by hardening data binding, stabilizing Android tooling, and expanding theming capabilities. The changes reduce debugging time, boost reliability of local development workflows, and strengthen CI stability across multiple repos.

October 2025

1 Commits • 1 Features

Oct 1, 2025

Month: 2025-10 — Focused work on dotnet/maui delivering a targeted refactor of the color handling subsystem to improve maintainability, performance, and test reliability. The changes prepare the codebase for simpler future enhancements and strengthen color parsing across UI components and the XAML source generator.

September 2025

1 Commits

Sep 1, 2025

September 2025 monthly summary for repository: dotnet/android. Focused on improving interop reliability between Mono.Android and CoreCLR by addressing delegate marshaling to native function pointers. This work reduces runtime failures during delegating and exporting delegates, enabling broader Android interop scenarios and smoother developer experience.

August 2025

2 Commits • 1 Features

Aug 1, 2025

August 2025 monthly summary for dotnet/runtime focusing on Android-related TLS capability detection and RSA verification behavior.

July 2025

2 Commits • 1 Features

Jul 1, 2025

July 2025 performance highlights: Implemented a cross-runtime GC bridge between CoreCLR and Java GC in dotnet/android to coordinate object lifetimes for hybrid .NET/Java workloads, enhancing memory management and stability. Re-enabled the Android test LargeHeaders_TrickledOverTime_ProcessedEfficiently on 64-bit Android with correct skip behavior on 32-bit devices, improving test reliability across architectures. Overall impact: reduced memory leaks and crash risk in long-running apps, stronger cross-platform reliability for Android workloads, and clearer QA feedback. Technologies/skills demonstrated: cross-language interoperability (CoreCLR ↔ Java GC), memory management optimization, architecture-aware testing, Android platform testing, and multi-repo collaboration.

June 2025

2 Commits • 2 Features

Jun 1, 2025

June 2025: Two major features delivered for the dotnet/android repo, focusing on performance, stability, and future interop work: CoreCLR JNI-to-Managed Type Mapping Cache and GC Bridge refactor (singleton ManagedValueManager + SimpleValueManager placeholder).

April 2025

2 Commits • 2 Features

Apr 1, 2025

April 2025 — dotnet/android: Key features delivered: 1) Code cleanup in JreRuntime.cs: removed the unused GetAssemblyLocation, eliminating a suppressed trimmer warning and reducing dead code maintenance. 2) Android networking security improvement: migrated to the .NET 9 certificate loading API to harden certificate validation and address potential null-reference issues. Major bugs fixed: eliminated the suppressed trimmer warning and mitigated potential null-reference in certificate handling. Overall impact: reduces maintenance burden, improves build stability, and strengthens security for Android networking. Technologies/skills demonstrated: C#, .NET 9 APIs, Android runtime (Mono.Android), and code hygiene practices (dead code elimination, trimmer warning mitigation).

March 2025

5 Commits • 2 Features

Mar 1, 2025

March 2025: Delivered performance and reliability improvements for Android interop in dotnet/android. Key features include a pre-generated, binary-search-based Android NativeAOT type map, and CoreCLR Android interop marshal methods behind a feature flag with correct app init and safe wrapper generation. Fixed a critical MAUI/CoreCLR crash by overriding GetInvokerTypeCore to correctly locate invoker types for abstract classes, and improved IL generation robustness by removing br.s in large switch tables. Impact: faster startup, lower memory footprint, fewer runtime exceptions, and more robust cross-platform Android/Mobile bindings; demonstrated strong proficiency in C#, IL generation, NativeAOT, MAUI, and Android interop.

February 2025

1 Commits • 1 Features

Feb 1, 2025

Monthly summary for 2025-02 focusing on feature delivery for Xamarin.Android interop and cross-runtime compatibility.

December 2024

4 Commits • 3 Features

Dec 1, 2024

December 2024 monthly summary: Delivered API and compiler improvements across Maui and Arcade, focused on expanding external accessibility, strengthening data-type safety, and refining Helix job results workflows. Key outcomes include public exposure of ResourceDictionary.SetAndLoadSource, DoesNotInheritDataTypeAttribute support in XamlC, and a controlled Helix API job results endpoint rollout with a subsequent rollback to address regressions, underscoring a disciplined approach to feature deployment and stability.

November 2024

1 Commits

Nov 1, 2024

November 2024 — NirmalKumarYuvaraj/maui Key features delivered: - MAUI Data Binding: Delay binding context type-check until the relative binding source is resolved, fixing misreported type mismatches. Major bugs fixed: - Correctly report type mismatches only after binding source resolution; added tests to cover the scenario. Overall impact and accomplishments: - Increased reliability and robustness of MAUI data binding; reduced false positives, improving developer productivity and UI correctness; enhanced test coverage with new tests. Technologies/skills demonstrated: - C# / .NET MAUI internals, data binding, test-driven development, focused refactoring, and commit-based traceability. Commit reference: - ff86add5061949e52b53ae2a79d96d1e99c96962a ("[X] Delay binding context type check until relative binding source is resolved (#25600)")

October 2024

1 Commits • 1 Features

Oct 1, 2024

Month: 2024-10 — Delivered core cross-platform AOT compatibility and serialization optimizations in the NirmalKumarYuvaraj/maui repository. The changes enhance Windows AOT reliability, improve performance via source-generated JSON serialization, and reduce build-time noise by cleaning up warning suppressions and compiler response files. The work strengthens cross-platform consistency, maintainability, and release readiness, enabling faster iterations and a better developer experience.

Activity

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Quality Metrics

Correctness93.2%
Maintainability87.4%
Architecture91.0%
Performance85.6%
AI Usage26.4%

Skills & Technologies

Programming Languages

CC#C++ILJavaXAMLXMLYAMLplaintext

Technical Skills

.NET Android Development Java Interop Runtime Unit Testing.NETAOT CompilationAPI DesignAPI IntegrationAndroidAndroid DevelopmentAndroid NDKAndroid developmentAssembly MetadataAttribute Handling

Repositories Contributed To

5 repos

Overview of all repositories you've contributed to across your timeline

dotnet/android

Feb 2025 Feb 2026
8 Months active

Languages Used

C#C++ILJavaXMLYAMLplaintext

Technical Skills

Android DevelopmentCode GenerationLLVMMSBuildRuntime InteroperabilityXamarin

dotnet/maui

Oct 2025 Feb 2026
4 Months active

Languages Used

C#XAML

Technical Skills

C#Graphics ProgrammingUnit Testing.NETAndroid DevelopmentContinuous Integration

dotnet/runtime

Jul 2025 Nov 2025
3 Months active

Languages Used

C#C

Technical Skills

.NET Android Development Unit TestingAndroid DevelopmentAndroid NDKCryptography

NirmalKumarYuvaraj/maui

Oct 2024 Dec 2024
3 Months active

Languages Used

C#

Technical Skills

AOT CompilationCompatibilityJSON SerializationRefactoringWindows DevelopmentData Binding

dotnet/arcade

Dec 2024 Dec 2024
1 Month active

Languages Used

C#

Technical Skills

API IntegrationBackend DevelopmentCode ReversionSoftware Development