prek-setup-petems

Set up prek git hooks

When the user asks you to set up prek (or pre-commit hooks using prek), follow these steps carefully.

Step 1: Check for existing config

Look for existing hook configuration files:

• prek.toml
• .pre-commit-config.yaml

If either exists, ask the user whether to overwrite, merge with the new config, or leave it unchanged. Do not proceed until the user confirms. If the user chooses leave it unchanged, stop the workflow and report that no changes were made.

Step 2: Ensure prek is installed

Check if prek is available:

command -v prek

If not found, ask the user which installation method they prefer:

• brew install prek (macOS/Linuxbrew)
• cargo install prek (Rust toolchain)
• pipx install prek (Python)

After installation, verify with:

prek --version

Step 3: Detect project languages

Use Glob to check for marker files that indicate which languages the project uses:

Marker files	Language
pyproject.toml, setup.py, requirements.txt, Pipfile	Python
package.json	JavaScript/TypeScript
go.mod	Go
Cargo.toml	Rust
Gemfile, *.gemspec	Ruby
**/*.tf	Terraform
Package.swift, *.xcodeproj	Swift
pom.xml, build.gradle, build.gradle.kts	Java/Kotlin
**/*.sh	Shell
**/*.md, hugo.toml, hugo.yaml, config.toml (Hugo), mkdocs.yml	Markdown/Blog

Report detected languages to the user before continuing.

Step 4: Build prek.toml

Build a prek.toml config file using the native TOML format (recommended by prek).

Universal hooks (always included)

[[repos]]
repo = "https://github.com/pre-commit/pre-commit-hooks"
rev = "v6.0.0"
hooks = [
  { id = "trailing-whitespace" },
  { id = "end-of-file-fixer" },
  { id = "check-yaml" },
  { id = "check-json" },
  { id = "check-merge-conflict" },
  { id = "detect-private-key" },
  { id = "check-added-large-files" },
]

Language-specific hooks

Only include sections for detected languages:

Python:

[[repos]]
repo = "https://github.com/astral-sh/ruff-pre-commit"
rev = "v0.15.7"
hooks = [
  { id = "ruff", args = ["--fix"] },
  { id = "ruff-format" },
]

JavaScript/TypeScript:

[[repos]]
repo = "https://github.com/pre-commit/mirrors-prettier"
rev = "v3.1.0"
hooks = [
  { id = "prettier" },
]

Go:

[[repos]]
repo = "https://github.com/golangci/golangci-lint"
rev = "v2.11.3"
hooks = [
  { id = "golangci-lint" },
]

Rust:

[[repos]]
repo = "local"
hooks = [
  { id = "cargo-fmt", name = "cargo fmt", entry = "cargo fmt --", language = "system", types = ["rust"] },
  { id = "cargo-clippy", name = "cargo clippy", entry = "cargo clippy --all-targets --all-features -- -D warnings", language = "system", types = ["rust"], pass_filenames = false },
]

Ruby:

[[repos]]
repo = "https://github.com/rubocop/rubocop"
rev = "v1.85.1"
hooks = [
  { id = "rubocop" },
]

Terraform:

[[repos]]
repo = "https://github.com/antonbabenko/pre-commit-terraform"
rev = "v1.105.0"
hooks = [
  { id = "terraform_fmt" },
  { id = "terraform_validate" },
  { id = "terraform_tflint" },
]

Swift:

[[repos]]
repo = "https://github.com/nicklockwood/SwiftFormat"
rev = "0.60.1"
hooks = [
  { id = "swiftformat" },
]

[[repos]]
repo = "https://github.com/realm/SwiftLint"
rev = "0.63.2"
hooks = [
  { id = "swiftlint" },
]

Shell:

[[repos]]
repo = "https://github.com/shellcheck-py/shellcheck-py"
rev = "v0.11.0.1"
hooks = [
  { id = "shellcheck" },
]

Java/Kotlin:

[[repos]]
repo = "https://github.com/macisamuele/language-formatters-pre-commit-hooks"
rev = "v2.16.0"
hooks = [
  { id = "pretty-format-java", args = ["--autofix"] },
  { id = "pretty-format-kotlin", args = ["--autofix"] },
]

Markdown/Blog:

[[repos]]
repo = "https://github.com/igorshubovych/markdownlint-cli"
rev = "v0.48.0"
hooks = [
  { id = "markdownlint", args = ["--fix"] },
]

[[repos]]
repo = "https://github.com/pre-commit/mirrors-prettier"
rev = "v3.1.0"
hooks = [
  { id = "prettier", types_or = ["markdown", "yaml"], args = ["--prose-wrap", "preserve"] },
]

Present config before writing

Show the assembled prek.toml to the user and ask for confirmation before writing it. Make any requested adjustments first.

Step 5: Install hooks

Run prek install, handling potential global hooksPath conflicts:

git -c core.hooksPath=.git/hooks prek install

Step 6: Run initial check

Run prek across all files to catch and auto-fix issues:

prek run --all-files

If there are auto-fixable issues, let prek fix them and re-run up to 3 times. If issues still remain (or output does not converge), stop and report remaining failures for manual intervention.

Step 7: Stage config (do NOT commit)

Stage only the new prek.toml and files modified by this prek run (do not stage unrelated pre-existing changes), then do not commit.

Tell the user:

• Setup is complete
• Files are staged and ready to commit when they are satisfied
• They can run prek autoupdate later to pin hooks to the latest revisions