pypa/hatch

Add flag for fresh Environment

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#2138 opened on Dec 9, 2025

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 (3 comments) (0 reactions) (0 assignees)Python (4,451 stars) (240 forks)batch import
enhancementgood first issue

Description

Description

Currently, the environment is reused between runs. What I want is a flag that uses its own fresh environment for each specific run.

Use case/motivation

dev-mode = false installs the project as non-editable whl mode, so when you do update the project code, the environment doesn't pick it up, and we need to first hatch env remove [environment-name] then run the code. If we had a flag for fresh env, that would go well with dev-mode = false

Related issues

https://github.com/pypa/hatch/issues/2134#issuecomment-3622375564 Another way to approach this problem is by checking if the project whl needs to be reinstalled (uninstalled then installed) This requires

  1. Check the src dir for changes
  2. Check BuildHook for changes
  3. Check MetadataHook for changes If yes, reinstall!

This is actually more performant than having to recreate the whole environment. But I figure it'd be harder to implement.

Thus, a clean-env flag for now would do, as it only requires making a time-based hashed env for each session.

Are you willing to submit a PR?

  • Yes I am willing to submit a PR!

Code of Conduct

Contributor guide

Tech stack
python
Domain
developer experiencetooling
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic understanding of HatchPython environment management
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
The issue asks for a flag (e.g., fresh) to create a fresh environment per run. The discussion in the related issue (https://github.com/pypa/hatch/issues/2134#issuecomment 3622375564) suggests an alternative: detecting changes to reinstall the wheel. For now, a simpler approach is to implement a time based hashed environment name. Key files to investigate: hatch/env/core.py or similar environment creation logic. The feature should be added as a CLI option and potentially a config setting.