# Environment Pinning: uv + pyproject.toml, CUDA Version Matrix, and Container Recipes

> Source: https://sukruyusufkaya.com/en/learn/fine-tuning-cookbook/ftc-environment-pinning-uv-cuda-matrix-containers
> Updated: 2026-05-14T14:42:49.189Z
> Category: Fine-Tuning Cookbook (Model-by-Model)
> Module: Part 0 — Engineering Foundations
**TLDR:** Second half of reproducibility: pin lib versions, understand the CUDA matrix, write Docker/Apptainer recipes. Where uv beats pip+poetry by 10-100x, the CUDA 12.4 / PyTorch 2.5 stack for RTX 4090, compatibility matrix for FT frameworks (TRL, Unsloth, Axolotl).