Gitronics lets you decompose a monolithic MCNP input file into independent, version-controllable components — universe filler models, an envelope structure, and separate data cards — and reassemble them at build time via a YAML configuration.
Full documentation: fusion4energy.github.io/gitronics
| Problem with monolithic models | Gitronics solution |
|---|---|
git diff is unreadable |
Each component is a separate file |
| Running variants means copying the whole file | Override only the fields that change |
| Teams can't work on sub-models in parallel | Each filler model is independent |
| Hard to know exactly what was run | Commit hash and timestamp written into every assembled file |
pip install gitronicsRequires Python 3.9+. Pre-built wheels for Linux, macOS, and Windows are published to PyPI — no Rust toolchain needed.
Migrate an existing model:
gitronics migrate path/to/my_model.mcnp --output-path ./my_projectBuild a model:
gitronics build my_project/configurations/baseline.yaml --output-path my_project/output/Get help:
gitronics --help
gitronics build --help
gitronics migrate --helpmy_project/
├── configurations/
│ ├── baseline.yaml ← declares which fillers go where
│ └── variant_A.yaml ← inherits baseline, overrides selected envelopes
├── output/
│ └── .gitignore
└── reference_model/
├── envelope_structure.mcnp
├── filler_models/
│ ├── component_A.mcnp
│ └── component_B.mcnp
└── data_cards/
├── materials/
├── sources/
└── tallies/
project_roots: [..]
envelope_structure: envelope_structure
source: dt_plasma
materials: [all_materials]
tallies: [tritium_breeding_ratio]
envelopes:
blanket_inner: blanket_v3
blanket_outer: blanket_reference
divertor: null # void — no FILL card insertedConfigurations support inheritance: a variant config can set overrides: baseline.yaml and override only the fields that differ.
The full documentation covers installation, CLI reference, configuration options, best practices, and worked examples: