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v2.18.0 Release Notes

Release Date: 2026-02-17 Commit: 2742d869

Overview

v2.18.0 delivers a fully functional headless simulation engine in the gecko-simulation-core module, enabling real circuit simulation without the GUI. This release implements the complete Modified Nodal Analysis (MNA) solver, domain coupling infrastructure, and REST API enhancements for detailed progress tracking.

What's New

Real MNA Circuit Solver (Phase 2-3)

The core simulation engine now performs actual circuit analysis:

  • MatrixSolver - Modified Nodal Analysis matrix A, vector b, and LU decomposition
  • ComponentCurrentCalculator - Post-solve current calculation for R, L, C, switches, and sources
  • InitialConditionSolver - Automatic calculation of initial capacitor voltages and inductor currents
  • Support for all three integration methods:
  • Backward Euler (1st order, stable for stiff circuits)
  • Trapezoidal (2nd order, balanced accuracy)
  • Gear-Shichman (variable order, adaptive dynamics)
  • CircuitNetlist / NetlistBuilder - Topology-aware netlist parsing from .ipes files
  • ControlNetlist - Headless control block execution per time step

Domain Coupling (Phase 4)

Real multi-domain simulation orchestration:

  • DomainCoupler - Coordinates LK (electrical) ↔ CONTROL ↔ THERM (thermal) data exchange
  • Node voltages transferred to control blocks each simulation step
  • Control signals applied back to circuit sources and switches
  • Thermal domain integration for loss-based temperature feedback

Simulation Engine Enhancements (Phase 1 & 5)

Production-ready headless simulation:

  • SimulationProgress - Detailed metrics (preCalcProgress, mainSimProgress, currentStep, totalSteps, estimatedRemainingMs)
  • HeadlessSimulationEngine pause/resume/isPaused/getDetailedProgress() methods
  • Real MNA solver loop replacing placeholder waveforms
  • Async simulation execution with cancellation support
  • Progress callbacks for UI integration

REST API Enhancements (Phase 6)

Enhanced simulation API with detailed progress:

  • solverType field in simulation requests (backward-euler, trapezoidal, gear-shichman)
  • progressDetails in simulation responses with 7 metrics fields
  • Detailed progress endpoint: GET /api/v1/simulations/{id}/progress
  • Export simulation results: GET /api/v1/simulations/{id}/export
  • Pause/resume operations: POST /api/v1/simulations/{id}/pause, POST /api/v1/simulations/{id}/resume

Test Coverage

  • Core module: 1,711 → 1,809 tests (+98 new tests)
  • 9 new production classes, 15 new test files
  • All 7,315 tests passing across all modules

Breaking Changes

None — fully backward compatible.

Upgrade Notes

REST API users: simulation status now includes progressDetails with detailed breakdown.

Architecture Improvements

New Classes in gecko-simulation-core:

  • gecko.simulation.CircuitSolver - Main MNA solver entry point
  • gecko.simulation.DomainCoupler - Inter-domain communication orchestrator
  • gecko.simulation.control.ControlNetlist - Headless control block executor
  • gecko.math.MatrixSolver - LU decomposition and forward/back substitution
  • gecko.circuit.component.ComponentCurrentCalculator - Post-solve current computation
  • gecko.circuit.simulation.InitialConditionSolver - IC calculation
  • gecko.circuit.netlist.NetlistBuilder - Enhanced topology analysis

REST API Classes:

  • gecko.rest.api.dto.ProgressDetails - Detailed progress response
  • gecko.rest.api.controller.SimulationProgressController - Progress endpoint handler
  • gecko.rest.api.service.ExportService - Results export (CSV/HDF5)

Deprecations

None.

Known Issues

None reported. Full test suite passing.

Performance

Simulation times (Docker on 4-core Intel i5):

Circuit Time Steps Duration
Buck (simple) 1,000 ~200 ms
3-phase inverter 10,000 ~2 sec
Complex buck PFC 100,000 ~30 sec

System Requirements

  • Java: OpenJDK 21 or later
  • Memory: 4 GB RAM (8 GB recommended for large circuits)
  • Storage: 200 MB for application
  • Display: 1280x720 resolution (HiDPI supported)
  • WSL Only: X server (VcXsrv, Xming, or WSLg)

Installation & Getting Started

See the Installation Guide for detailed platform-specific instructions.

After installation, check out:

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