rseng-reproducible-environmentslisted

# Reproducible software environments Use this skill when software must behave the same on another machine, a cluster, a CI runner, or a reviewer's laptop as it does on the author's. Two complementary tools deliver this: a per-project virtual environment that isolates the language interpreter and its libraries, and a container that packages the code together with its entire dependency stack. Reach for the virtual environment when developing or modifying code in one language; reach for the container when the environment must travel across machines, platforms, or pipelines unchanged. ## Pick the right level of isolation Match the tool to how far the software has to travel and what it depends on: - Language-specific virtual environment - isolates one interpreter/compiler version plus library versions for a single project. Default choice while developing, running, or modifying someone's code in one language. - Container (Docker, Apptainer/Singularity, Docker Compose) - packages the whole environment, including non-language system libraries and OS-level config. Choose when the code must run unchanged across collaborators' machines, clusters, or cloud, or plug into CI/CD. - System-level tools (Vagrant, NixOS, Packer) - reproduce a whole machine image or OS configuration as code. Use when the OS itself is part of what must be reproduced. - Workflow environments (Nextflow, Snakemake, Galaxy, CWL/WDL) - manage reproducible environments for multi-step, multi-tool ana