March 2026 summary: Delivered targeted feature improvements (Ktlint formatting scanning improvements and Code of Conduct doc updates), and significant build/tooling upgrades (disable scoverage for BSP, upgraded Coursier and Acyclic). These changes reduce resource usage, improve reliability, and enhance developer experience across Mill users and BSP clients.

February 2026 (2026-02) monthly summary for com-lihaoyi/mill: Delivered user-facing UX improvements, cross-platform reliability fixes, and codebase maintenance that collectively enhance build stability, security, and performance. Key outcomes include a new indicator for unknown total job count in the execution header, a Windows-friendly environment-variable lookup in TaskCtx, and a broad wave of dependency upgrades across core libraries and tooling. These changes reduce runtime ambiguity, improve cross-platform consistency, and strengthen the overall development experience while preserving API compatibility and maintainability.

January 2026 performance for com-lihaoyi/mill focused on stabilizing the developer experience, modernizing the build toolchain, and improving reliability across CI and local use. Delivered CLI/docs improvements, upgraded core dependencies for better performance and compatibility, expanded configurability and init workflows, and implemented safer code-generation practices. Fixed key tests and release issues to improve overall stability. Business value includes faster onboarding, shorter iteration cycles, more reproducible builds, and improved tooling for teams adopting Maven/Gradle converters and YAML project generation.

Month: 2025-12 — Focused on stability, testability, and environment-driven configuration to improve build reliability and developer productivity. Delivered targeted features and fixes that reduce global state, clarify output paths, and strengthen offline workflows, while ensuring correct dependency resolution across toolchains. The changes improve maintainability, safer cleanups, and faster iteration for users and contributors. Overall impact: - Reduced risk of stale constants and incorrect artifacts via OutFiles singleton refactor with deprecation of static fields. - Safer BSP/output handling by introducing MILL_BSP_OUTPUT_DIR and realigning default paths under a dedicated .bsp directory to improve cleanup and reduce nested outputs. - Expanded task execution semantics with Task.Uncached for external/system-bound work that must run every time. - Improved offline build experience for NativeImageModule and SpringBootModule by pre-fetching new dependencies required for offline usage. - Fixed dependency resolution for KSP >= 2.3 to ensure correct transitive behavior. Technologies/skills demonstrated: - Scala/Java interop and refactoring to non-static state patterns (OutFiles singleton) - Environment-driven configuration (MILL_BSP_OUTPUT_DIR) and BSP path modeling - Task orchestration enhancements (Task.Uncached) and robust worker/module handling - Dependency management upgrades (Zinc, Scala, JLine, BouncyCastle, etc.) and compatibility considerations - Bug fixing with clear impact on reliability and developer experience

November 2025 (2025-11) monthly summary for com-lihaoyi/mill. Focused on reliability, ergonomics, and offline build readiness. Key features delivered include improved API ergonomics and tooling support, enhanced docs, and broader dependency hygiene. Major fixes and improvements reduce runtime risks and improve developer experience for Mill-based builds. Key achievements highlights: - RelocateModule: fix main class selection for older spring-boot-tools versions (bug) — ensures correct entry point selection and compatibility with older toolchains. - Named parameters for methods with many parameters (feature) — simplifies API usage and reduces parameter-related errors (#6105). - Add AutoClosable to SpringBootTools worker (feature) — improves resource management and safety (#6179). - AssemblyModule.prepareOffline to resolve worker dependencies offline (feature) — enables offline builds and better offline workflow (#6238). - Dependency upgrades (batch) — updated critical libraries across the project (commons-io, classgraph, semanticdb, Ammonite, snakeyaml-engine, Play framework, ASM, etc.) to align with current compatibility and security baselines (#6175-#6229). Major bugs fixed: - AndroidDataBindingImpl logic error (fix) (#6154). - Return imports from BuildWriter.imports without mutating parameters (fix) (#6140). - Fix API leakage in Sonatype publisher (bug) (#6256). - Silence/fix warning about workers not implementing AutoCloseable (bug) (#6259). Overall impact and accomplishments: - Strengthened compatibility with Spring Boot tooling, improved API ergonomics and safety, and enhanced build reliability with offline capabilities. The project now exhibits more predictable behavior across toolchains, clearer API usage, and safer resource handling. Documentation and changelog improvements also help downstream teams adopt changes with less friction. Technologies/skills demonstrated: - Scala ecosystem, Ammonite-based tooling, and build tooling engineering. - Dependency management at scale, integration testing, and manual verification of changes. - Documentation, Spring-related tooling, and explicit work-directory handling for readability and correctness.

October 2025: Focused on expanding cross-language capabilities, developer experience, and maintainability for Mill. Delivered Java code generation for Protocol Buffers in ScalaPBModule to broaden Java/Scala interoperability; stabilized the CLI UX with clearer messaging and deprecated-option handling; modernized the build and runtime to Scala 3-friendly dependencies; centralized API/docs coverage including contrib and non-stable modules and aligned Android tooling. These changes unlock broader adoption, reduce onboarding time, and improve maintainability and documentation quality.

September 2025 (Month: 2025-09) for com-lihaoyi/mill demonstrated strong delivery across core build tooling, Kotlin integration, and developer experience improvements. Key outcomes include targeted enhancements to the MillURLClassLoader for robust user project sub-package loading and parallel registration, Kotlin Build Tools API support for Kotlin 2.0+/2.1+, documentation and deprecation clarity improvements, a broad dependency refresh to improve stability and security, and performance improvements in website link checks via asynchronous processing. These efforts collectively increase build reliability, reduce developer friction, and ensure compatibility with evolving runtimes while better communicating changes to users.

August 2025 for com-lihaoyi/mill focused on delivering high-value features, improving build and docs reliability, and expanding platform support. Key work spanned API exposure, site/docs tooling, Android CI reliability, and dependency health, underscoring a strong emphasis on business value (stability, portability, and developer productivity).

July 2025 performance summary for com-lihaoyi/mill: Delivered substantive feature work and stability improvements across the core build and tooling. Highlights include PMD integration enhancements with API exposure and improved exit code handling; maintenance through targeted dependency upgrades; BSP module API refactor with dedicated API surface and improved worker diagnostics; and workflow improvements for documentation and API docs generation. These changes deliver clearer API boundaries, more reliable CI behavior, and faster onboarding for contributors and IDE integrations.

June 2025: Focused on stabilizing BSP integration, expanding migration tooling for JVM options, and refactoring API surfaces to improve usability and maintainability. Major effort shipped across the Mill core repo, delivering reliability improvements, enhanced migration workflows, and a cleaner, more evolvable API surface that supports faster iteration and external tool integration.

May 2025 focused on packaging flexibility and build-system robustness for Mill. Delivered self-executable JAR packaging via RepackageModule, enabling production-ready deployments with a simple repackagedJar task. Completed a major modernization of the Mill build system, including tooling upgrades, code generation reorganization, caching improvements, IDE-related source presentation cleanup, bootstrap backward-compatibility fixes, and publishing/dependency-management enhancements. These changes reduce deployment friction, accelerate local and CI builds, and improve long-term maintainability and scalability of the project.

April 2025 focused on stabilizing and accelerating the Kotlin-driven modernization in the Mill project, while fortifying the build system, improving offline capabilities, and cleaning up API usage. Key work spans Kotlin overhaul (RunModule adjustments, Kotlin plugin setup, and KotlinModule cleanup), API modernization (replacing deprecated ZincWorkerXxx/mill APIs and log streams), offline mode support, and build/tooling improvements alongside documentation and dependency upgrades. This set of changes reduces technical debt, enables offline workflows for users, and enhances overall build reliability and maintainability for Mill-based projects.

March 2025: Delivered Kotlin support and enhanced reliability across the Mill build system, driving developer productivity and stability. Key outcomes include Kotlin language support for the BuildInfo module and first-class Kotlin compiler plugin integration, robust BSP main-class discovery via ClassGraph, dependency-management refactor to eliminate circular dependencies, comprehensive build-tool upgrades to latest stable versions, and targeted bug fixes to harden string coloring and trace handling.

February 2025 monthly summary for com-lihaoyi/mill: Focused on stability, maintainability, and clarity across the codebase. Key features delivered include PalantirFormatModule output enhancement showing Java file counts; CI/test stability improvements (locale standardization, reduced dependency analysis to core modules, and bootstrap patch updates); documentation quality improvements via AsciiDoc migration and Graphviz block fixes; centralized dependency version management to remove hard-coded versions; and targeted Java/Kotlin code quality improvements. Overall, these efforts reduced build risk, improved developer experience, and clarified downstream tooling outputs.

January 2025 monthly summary for com-lihaoyi/mill focusing on reliability, visibility of module relationships, and operational efficiency.

December 2024: Focused on delivering business value through an automated, safer release workflow and a broad set of dependency updates to improve stability and security across the mill repository. Key outcomes include enabling prerelease announcements after sanity checks and artifact availability, and consolidating maintenance to align tooling and libraries with current standards.

November 2024 monthly summary focusing on delivering business value through reliable CI/CD, build stability, and tooling modernization across two repositories (com-lihaoyi/mill and guardian/scala-steward). Key outcomes include faster and more reliable artifact publishing, improved build correctness when Mill versions change, and clearer release/documentation workflows. Key features delivered - com-lihaoyi/mill: CI/CD improvements and artifact management with a dedicated build-artifacts workflow, artifact caching, naming consistency, and enhanced artifact publishing steps across publish workflows (supported by commits that refined publish-artifacts actions and artifact reuse in publish jobs). - Inspect command enhancements: improved module/parent resolution, dependencies visibility, and standardized output formatting for better developer feedback. - BSP documentation improvements: new install command and editor compatibility notes to streamline BSP setup. - Mill version readiness: updates to release notes and CI for Mill 0.11.13 to ensure accurate version tracking. Major bugs fixed - Mill incremental compilation invalidation on Mill version change: invalidated incremental compilation state to prevent undercompile issues when the version changes. - Dependency cleanup: removed unused junixsocket to simplify the build and prevent related issues. - Mill server-mode test stability (guardian): fixed a test by updating command usage to --no-server to ensure CI test stability. Overall impact and accomplishments - Significantly improved CI reliability and artifact publishing efficiency, reducing publish time and flakiness across GitHub Actions workflows. - Increased build correctness across Mill version bumps by implementing incremental compilation invalidation, preventing subtle undercompile scenarios. - Enhanced developer experience with better visibility into dependencies and module structure via inspect improvements, and clearer BSP setup guidance. - Strengthened build tooling and reproducibility through Mill tooling modernization in guardian/scala-steward (millw adoption, release-page usage) and updated formatting. Technologies/skills demonstrated - Mill tooling and Millw-based workflows, including artifact management, caching, and publish steps; Java 17 usage in CI. - Build reproducibility and version-locked tooling via millw, release-page sourcing, and Mill 0.11.13 updates. - BSP protocol and editor compatibility considerations; scalable, maintainable CI/CD pipelines on GitHub Actions. - Test stability strategies in CI for server-mode execution and robust dependency management.

October 2024 (com-lihaoyi/mill): Delivered reliability and maintainability enhancements across configuration, dependency management, and documentation workflows. Key features include dynamic environment variable interpolation in config files with updated docs and encapsulation of the envInterpolatorPattern; and overall improvements to dependency management. Major bugs fixed include correct reporting of runModuleDeps cycles through fixed recursive dependency calculation. Documentation workflow was stabilized by disabling edit links for legacy versions, reducing noise in docs. These efforts reduce build fragility, improve developer productivity, and accelerate feature delivery.