October 2025 monthly summary focusing on delivering modernized build, API improvements, release readiness, and reliability across powsybl-entsoe, powsybl-core, powsybl-open-loadflow, and powsybl-diagram. Key business value includes Java 21 upgrade for security and compatibility, API refactor to simplify configuration via RunParameters, and enhanced test coverage and release discipline.

September 2025: Implemented a major modernization of powsybl-diagram by upgrading to Java 21 and aligning CI to JDK 21. Bumped powsybl-parent to 24 and signaled long-term maintenance changes by deprecating ForceLayout and Spring (and their tests) with since 5.0.0 to prepare for a future major release. This work improves compatibility with newer Java features, strengthens CI reliability, and clarifies roadmap for users and contributors.

August 2025: Security-focused CI/CD improvement for powsybl-core by implementing least-privilege GitHub Actions workflow. Reduced blast radius while preserving build reliability. Key change: remove broad workflow permissions and apply minimum necessary permissions at the job level.

July 2025 monthly summary focused on stability, security, backward compatibility, and localization across core, diagram, entsoe, open-rao, and pypowsybl. Delivered edge-case serialization tweaks, terminal handling improvements, and widespread dependency upgrades with targeted test/config updates to reduce risk, improve interoperability, and streamline builds for downstream teams.

Summary for 2025-06: Key features delivered: - PSS/E Import Backtracking Protection: Adds backtracking protection to LegacyTextReader.processText with a unit test, improving robustness of PSS/E data import. - Flexible Network Element Identifier Matching: Extends IdWithWildcardsNetworkElementIdentifier to support a broad range of UTF-16 characters (including spaces) and enables a custom wildcard character for more flexible identifier matching. - Dynamic Network Element Naming Strategies: Introduces a NamingStrategiesServiceLoader to dynamically discover and select naming strategies for network elements, enabling default and custom implementations. - Security Hardening: Regex and XML Processing: Replaces Java regex with RE2J to mitigate ReDoS, hardens XML parsing, and adds object-input-filter support for SparseMatrix deserialization. - IIDM Version 1.14 Compatibility and OperationalLimitsGroup Metadata: Bumps IIDM to version 1.14 and adds arbitrary key-value properties on OperationalLimitsGroup objects for richer metadata and serialization support. Major bugs fixed: - Deserialization End Task Execution Guard: Ensures each step of a deserialization end task is executed only once to prevent redundant operations. - CreateVoltageLevelTopology Data Integrity Improvements: Prevents creating busbar sections at occupied positions and aligns node index initialization with existing topology. - InMemoryZipFileDataSource.listNames regex reliability: Fixes listNames regex handling to improve zip file listing robustness. Overall impact and accomplishments: - Strengthened data import reliability, security, and interoperability across core, diagram, and pypowsybl modules. - Improved stability for PSS/E imports, network element identification, and dynamic naming strategies, enabling smoother integration with external datasets and tools. - Enhanced security posture for data processing and deserialization, reducing exposure to ReDoS and XXE attacks while tightening serialization safety. Technologies/skills demonstrated: - Java, service loader patterns, UTF-16 character handling, and advanced string matching. - Security hardening through RE2J integration, XML processing safeguards, and object-input-filter usage. - Robust testing practices with unit tests for critical flows. - Dependency management and version alignment (IIDM 1.14) and multi-repo coordination across core, diagram, and Python bindings.

May 2025 monthly summary for powsybl-open-loadflow: Delivered key stability and maintainability improvements with a Jacoco coverage reporting fix and a routine dependency upgrade to ensure compatibility and build reliability. These changes reduce build variance and improve QA readiness for next release.

April 2025 monthly summary focusing on key accomplishments across powsybl-core: feature delivery and reliability improvements with a focus on backward compatibility and data integrity. Emphasis on business value, maintainability, and traceability of changes.

March 2025 performance: Delivered cross-version extension support and import resilience in powsybl-core, hardened loader and deserialization flows, revamped transformer replacement logic, and maintained data integrity in CGMES exports. Implemented dependency upgrades and release readiness across core, entsoe, and open-rao, with extensive testing on edge cases and version-bound behavior.

February 2025 monthly summary focusing on features delivered, bugs fixed, and business impact across the codebase. Key outcomes include improved data exchange reliability for CGMES by adding backward-compatible deserialization with a SerDe layer and area-ID deduplication, along with focused testing for boundary conditions. In parallel, CI visibility and accuracy were enhanced by correcting GitHub Actions badge links and references across four repositories, improving stakeholder confidence in build status and release readiness.

January 2025: Build stability and dependency hygiene improvements in powsybl-open-rao. No new user-facing features were released this month; focus was on cleaning up dependencies to prevent build failures and reduce maintenance burden. The main change removed a non-existent dependency to ensure reliable CI and future upgrades.

December 2024: Delivered cross-repo enhancements and stability improvements across powsybl-diagram, powsybl-core, pypowsybl, powsybl-open-loadflow, and powsybl-entsoe. Key features and fixes include: GraphMetadata serialization order fix to ensure consistent attribute ordering; CGMES import enhancement to support voltages without names; dependency upgrades to powsybl-parent v20 and related version bumps; Entsoe CI snapshot build fix; core/open-loadflow upgrade to core 6.6.0; DC load flow reporting enhancement with test updates. Business value: improved data interoperability, more reliable tests and CI, and faster, safer release readiness.

Monthly performance summary for 2024-11 focused on delivering updates that enhance stability and user guidance for the Open Load Flow (OLF) feature set, within the powsybl-open-loadflow repository. The month emphasized dependency management and documentation maintenance to support reliable operation and easier user adoption.