Garbled stdout (spinner/control characters) when running prek in Neovim/Fugitive

[pesap]

Summary

On my Neovim setup I use Fugitive to commit, which runs my pre-commit hooks. When I run pre-commit directly, the stdout renders correctly. But when it runs via prek , the output includes strange/garbled characters (looks like control sequences from a progress spinner).

Is this expected? If not, is there a way to disable the spinner/progress animation so the output is plain text?

Environment:

• Neovim
• vim-fugitive (commit workflow)
• pre-commit hooks run during commit

Platform

Darwin 24.6.0 arm64

Version

0.2.29

.pre-commit-config.yaml

default_stages:
  - pre-commit

default_install_hook_types:
  - pre-commit
  - commit-msg
  - pre-push

repos:
  - repo: local
    hooks:
      - id: ruff-format
        name: ruff format
        entry: uv run ruff format --verbose
        language: system
        types_or: [python, pyi]

      - id: ruff-check
        name: ruff check
        entry: uv run ruff check --fix --config=pyproject.toml
        language: system
        types_or: [python, pyi]

      - id: ty-check
        name: ty check
        entry: uv run ty check src/
        language: system
        types_or: [python, pyi]

  - repo: builtin
    hooks:
      - id: trailing-whitespace
      - id: check-added-large-files
      - id: end-of-file-fixer
      - id: detect-private-key
      - id: trailing-whitespace
      - id: check-added-large-files
      - id: check-case-conflict
      - id: end-of-file-fixer
      - id: fix-byte-order-marker
      - id: check-json
      - id: check-toml
      - id: check-yaml
      - id: check-xml
      - id: mixed-line-ending
      - id: check-symlinks
      - id: check-merge-conflict
      - id: detect-private-key
      - id: check-executables-have-shebangs

  - repo: https://github.com/commitizen-tools/commitizen
    rev: v4.10.0
    hooks:
      - id: commitizen
        stages:
          - commit-msg

  - repo: local
    hooks:
      - id: pytest
        name: pytest (quick)
        entry: uv run pytest -q -m "not slow" --maxfail=1 --disable-warnings
        language: system
        types: [python]
        pass_filenames: false
        stages: [pre-push]


  - repo: https://github.com/astral-sh/uv-pre-commit
    # uv version.
    rev: 0.9.4
    hooks:
      - id: uv-lock

Log file

Here is an example of the render output that I see on neovim.

[2Kruff format..............................................................
^[[2K^[[1Aruff format..............................................................                   ^[[1A
^[[2Kruff format..............................................................Passed
^[[2Kruff check...............................................................
^[[2K^[[1Aruff check...............................................................                   ^[[1A
^[[2Kruff check...............................................................Passed
^[[2Kty check.................................................................
^[[2K^[[1Aty check.................................................................                   ^[[1A
^[[2K^[[1Aty check.................................................................                   ^[[1A
^[[2Kty check.................................................................Passed
^[[2Kdocstring coverage.......................................................
^[[2K^[[1Adocstring coverage.......................................................                   ^[[1A
^[[2Kdocstring coverage.......................................................Failed
- hook id: docstring-coverage
- exit code: 2

  error: Failed to spawn: `docstr-coverage`
    Caused by: No such file or directory (os error 2)
^[[2Ktrim trailing whitespace.................................................Passed
^[[2Kcheck for added large files..............................................Passed
^[[2Kfix end of files.........................................................Passed
^[[2Kcheck for case conflicts.................................................Passed
^[[2Kfix utf-8 byte order marker..............................................Passed
^[[2Kcheck json...........................................(no files to check)Skipped
^[[2Kcheck toml...........................................(no files to check)Skipped
^[[2Kcheck yaml...........................................(no files to check)Skipped
^[[2Kcheck xml............................................(no files to check)Skipped
^[[2Kmixed line ending........................................................Passed
^[[2Kcheck for broken symlinks............................(no files to check)Skipped
^[[2Kcheck for merge conflicts................................................Passed
^[[2Kdetect private key.......................................................Passed
^[[2Kdon't commit to branch...................................................Passed
^[[2Kcheck that executables have shebangs.................(no files to check)Skipped
^[[2Kuv-lock..............................................(no files to check)Skipped
^[[2K

[shaanmajid]

Repro'd in 0.3.1.

printer.rs should use the same logic as run::USE_COLOR

[shaanmajid]

Is this expected? If not, is there a way to disable the spinner/progress animation so the output is plain text?

No, not expected. It is interesting cause running prek directly in Neovim worked fine, it's specifically as part of Fugitive that it gets garbled like this and the ANSI control characters show up.

Fugitive runs hooks through a pseudo-TTY that passes some of our checks to omit ANSI control characters, but it's not actually capable of handling them, which is why it shows up.

As a work around, you can configure PREK_QUIET=1 for now, but unfortunately that'll suppress all non-failed hooks, which might be a bit heavier than what you want.

[shaanmajid]

Fugitive properly sets TERM=dumb and NO_COLOR=1 but indicatif ignores it; might be worth an upstream report

[pesap]

Thanks for the prompt reply! Let me know if I can be of any help.

[shaanmajid]

Thanks for the report! Will hopefully be fixed in prek next release, and I submitted an upstream fix to indicatif as well :)

(indicatif is the dependency used to draw the progress bars fyi haha)