fix(python): clarify uv_venv_auto docs + prevent uv shim recursion in venv creation by halms · Pull Request #8402 · jdx/mise

halms · 2026-03-02T00:01:51Z

Two related fixes for python.uv_venv_auto:

Docs: The warning block on the Python page was misleading — it said uv_venv_auto = true is "deprecated", but only the true value is being phased out, not the setting itself. Rewrites the warning to clarify this, and also explains the practical difference between the legacy true behavior (exports UV_PYTHON with just the version string, letting uv pick any matching Python) vs the recommended approach (using tools.python.path to strictly bind uv to the exact mise-managed Python binary).

Bug fix: When uv_venv_auto = "create|source" is set and a mise shim for uv exists on PATH (e.g. from another project), create_python_venv was finding the shim via which_non_pristine("uv"). Running the shim calls mise exec, which re-enters env resolution and calls create_python_venv again — causing infinite subprocess recursion and an endless stream of "mise creating venv with uv at: ..." messages.

Fix adds which_no_shims() that excludes $MISE_DATA_DIR/shims from the PATH search, and uses it in create_python_venv. Also handles Ok(false) from create_python_venv in uv_venv() correctly (previously fell through to load_venv on a non-existent path).

gemini-code-assist · 2026-03-02T00:02:10Z

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses two key areas related to mise's Python uv virtual environment integration. Firstly, it enhances the documentation for python.uv_venv_auto to provide clearer guidance on its usage and the implications of different configuration values, particularly concerning UV_PYTHON. Secondly, it resolves a critical bug that could lead to infinite recursion when mise attempts to create a uv virtual environment while a mise uv shim is present in the system's PATH, ensuring stable and predictable virtual environment creation.

Highlights

Documentation Clarification: The documentation for python.uv_venv_auto has been updated to clarify that only the true value is being deprecated, not the setting itself. It also explains the difference in UV_PYTHON behavior between the legacy true value and newer string values, providing an example for strictly binding uv to a mise-managed Python interpreter.
Bug Fix: UV Shim Recursion: A critical bug causing infinite subprocess recursion when uv_venv_auto is enabled and a mise uv shim exists on PATH has been resolved. This was due to create_python_venv finding and invoking the mise shim, which would re-enter environment resolution.
New Utility Function: which_no_shims: A new function which_no_shims was introduced in src/file.rs. This function searches the PATH for executables but explicitly excludes the mise shim directory, preventing internal mise processes from recursively calling mise shims.
Improved Error Handling for Venv Creation: The uv_venv function now correctly handles cases where create_python_venv returns Ok(false) (indicating uv was not available for venv creation), preventing attempts to load a non-existent virtual environment.

Changelog

docs/lang/python.md
- Rewrote the warning block for python.uv_venv_auto = true to clarify that only the true value is deprecated, not the setting itself.
- Explained the difference in UV_PYTHON behavior between the legacy true value and newer string values.
- Added a configuration example to strictly bind uv to a mise-managed Python interpreter using tools.python.path.
e2e/core/test_python_uv_venv
- Updated test configurations from .mise.toml to mise.toml.
- Added a new test case to verify that mise's uv shim is not invoked during internal venv creation, preventing recursion.
src/config/env_directive/venv.rs
- Replaced the which_non_pristine function call with the new which_no_shims function when looking up the uv binary for venv creation.
src/file.rs
- Implemented a new public function which_no_shims that searches the PATH for an executable but explicitly excludes the mise shim directory to prevent recursive calls.
src/uv.rs
- Modified the create_python_venv call within uv_venv to use a match statement, allowing for proper handling of Ok(false) (indicating uv was not available) to prevent attempting to load a non-existent venv.

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gemini-code-assist

Code Review

This pull request introduces documentation clarifications and bug fixes for python.uv_venv_auto. The documentation is updated to clarify the deprecation of the true value. A bug causing infinite recursion when a mise shim for uv is in the PATH is fixed by adding a which_no_shims function to exclude the shim directory during executable lookups. A new e2e test verifies this fix. Additionally, the return value from the venv creation function is now handled correctly to prevent errors with non-existent venvs. The changes are well-implemented and I have no issues to report.

Copilot

Pull request overview

Improves python.uv_venv_auto behavior and documentation by clarifying legacy vs recommended configuration, and preventing infinite recursion when a uv shim is present on PATH during venv auto-creation.

Changes:

Fix uv_venv() to correctly handle create_python_venv() returning Ok(false) (skip loading a non-existent venv).
Add which_no_shims() and use it for internal uv lookup to avoid invoking mise shims (and recursive re-entry).
Update E2E coverage for shim-exclusion behavior and clarify Python docs around the legacy true setting value.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/uv.rs	Handle `Ok(false)` from venv creation to avoid loading a missing `.venv`.
src/file.rs	Introduce `which_no_shims()` to avoid shim-based recursion in internal tool lookups.
src/config/env_directive/venv.rs	Use `which_no_shims("uv")` when creating venvs.
e2e/core/test_python_uv_venv	Add regression test for shim recursion avoidance; switch config filename to `mise.toml`.
docs/lang/python.md	Clarify that only the `true` value is legacy, and document a stricter `UV_PYTHON` configuration pattern.

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src/file.rs

e2e/core/test_python_uv_venv

greptile-apps · 2026-03-02T00:09:20Z

Greptile Summary

This PR fixes a critical bug that caused infinite subprocess recursion when mise shims were on PATH during venv creation, and clarifies misleading documentation about the uv_venv_auto deprecation.

Key Changes:

Added which_no_shims() function to exclude $MISE_DATA_DIR/shims from PATH searches, preventing recursive shim invocation during venv creation
Fixed error handling in uv_venv() to correctly handle Ok(false) return value (previously would attempt to load non-existent venv)
Clarified documentation to explain that only uv_venv_auto = true is deprecated, not the setting itself
Added guidance on using UV_PYTHON with tools.python.path for strict Python interpreter binding
Added comprehensive test coverage for shim exclusion scenario
Updated test file naming from .mise.toml to mise.toml

Confidence Score: 5/5

This PR is safe to merge with no identified risks
All changes are well-implemented bug fixes with proper test coverage. The recursion fix addresses a real issue, error handling is improved, and documentation is clearer. No logical errors, security issues, or edge cases found.
No files require special attention

Important Files Changed

Filename	Overview
src/file.rs	Adds `which_no_shims()` function to prevent recursive shim invocation
src/uv.rs	Fixes error handling to properly handle `Ok(false)` from `create_python_venv()`
src/config/env_directive/venv.rs	Switches to `which_no_shims()` to avoid mise shim during venv creation

_{Last reviewed commit: d71e0b2}

jdx · 2026-03-02T00:10:43Z

bugbot run verbose=true

cursor · 2026-03-02T00:10:45Z

Bugbot request id: serverGenReqId_ce9f1153-3037-44dc-82c3-62279e95492e

The true value is considered legacy and will be deprecated in a future release (2026.7), but the setting itself is not going away. Clarify the difference between legacy `true` (exports UV_PYTHON with just the version number) and the new recommended approach (using `tools.python.path` to strictly pin uv to mise-managed Python). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

halms · 2026-03-02T00:31:57Z

@jdx, I pushed changes to address the Copilot comments which I think were valid.
This disabled the auto-merge again.

…_auto When `uv_venv_auto = "create|source"` is set and a mise shim for uv exists on PATH (from another project), `which_non_pristine("uv")` would find the shim. Running the shim invokes `mise exec`, which re-enters the same venv creation path, causing infinite subprocess recursion (printing "mise creating venv with uv at: ..." endlessly). Fix by adding `which_no_shims()` that excludes the mise shim directory from PATH searches, and using it in `create_python_venv`. Also handle the `Ok(false)` return case in `uv_venv()` so that when venv creation is skipped (e.g. uv unavailable), we correctly return None instead of falling through to `load_venv` on a non-existent path. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

@jdx

### 🚀 Features - **(hooks)** add task references to hooks and watch_files by @jdx in [#8400](#8400) - **(prepare)** add git-submodule built-in provider by @jdx in [#8407](#8407) - **(prepare)** add human-readable stale reasons to prepare output by @jdx in [#8408](#8408) - **(prepare)** add dependency ordering to prepare steps by @jdx in [#8401](#8401) - **(prepare)** add --explain flag for provider diagnostics by @jdx in [#8409](#8409) - **(prepare)** add per-provider timeout support by @jdx in [#8405](#8405) - **(prepare)** add blake3 content-hash freshness checking by @jdx in [#8404](#8404) - **(tasks)** monorepo vars and per-task vars by @halms in [#8248](#8248) ### 🐛 Bug Fixes - **(aqua)** restore bin_paths disk cache with fresh_file invalidation by @jdx in [#8398](#8398) - **(idiomatic)** use generic parser for idiomatic files by @risu729 in [#8171](#8171) - **(install)** apply precompiled options to all platforms in lockfile by @jdx in [#8396](#8396) - **(install)** normalize "v" prefix when matching lockfile versions by @jdx in [#8413](#8413) - **(prepare)** improve git submodule parser and fix check_staleness error handling by @jdx in [#8412](#8412) - **(python)** respect precompiled settings in lock file generation by @jdx in [#8399](#8399) - **(python)** clarify uv_venv_auto docs + prevent uv shim recursion in venv creation by @halms in [#8402](#8402) - **(task)** remove deprecated `# mise` task header syntax by @jdx in [#8403](#8403) - **(vfox)** avoid eager metadata loading during config file detection by @jdx in [#8397](#8397) - clarify GitHub attestations to be artifact ones by @scop in [#8394](#8394) - ignore comments in idiomatic version files by @iloveitaly in [#7682](#7682) ### 🚜 Refactor - unify archive detection by @risu729 in [#8137](#8137) ### 📚 Documentation - remove duplicated docs for npm.package_manager by @risu729 in [#8414](#8414)

Copilot AI review requested due to automatic review settings March 2, 2026 00:01

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halms force-pushed the docs/clarify-uv-venv-auto-deprecation branch from 4f0e548 to d71e0b2 Compare March 2, 2026 00:05

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jdx enabled auto-merge (squash) March 2, 2026 00:14

auto-merge was automatically disabled March 2, 2026 00:19
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halms force-pushed the docs/clarify-uv-venv-auto-deprecation branch from b14c3c0 to 176ad55 Compare March 2, 2026 00:26

halms force-pushed the docs/clarify-uv-venv-auto-deprecation branch from 176ad55 to c6442fd Compare March 2, 2026 00:43

jdx merged commit 4ba7aed into jdx:main Mar 2, 2026
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mise-en-dev mentioned this pull request Mar 2, 2026

chore: release 2026.3.0 #8406

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BrewTestBot mentioned this pull request Mar 2, 2026

mise 2026.3.0 Homebrew/homebrew-core#270150

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fix(python): clarify uv_venv_auto docs + prevent uv shim recursion in venv creation#8402

fix(python): clarify uv_venv_auto docs + prevent uv shim recursion in venv creation#8402
jdx merged 2 commits intojdx:mainfrom
halms:docs/clarify-uv-venv-auto-deprecation

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Confidence Score: 5/5

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