hk Setup

Configure hk git hooks with appropriate linters for any project.

When to Use This Skill

• User asks to set up pre-commit hooks
• User wants to add linting/formatting to a project
• User mentions hk, git hooks, or pre-commit
• User wants to enforce code quality on commits

Prerequisites

# Install hk (one of these)
brew install hk
mise use -g hk

Workflow

1. Detect Project Type

Look for these files to identify the project:

2. Check Available Tools

hk builtins  # List all built-in linters

See references/builtins.md for full catalog. Key builtins:

3. Generate hk.pkl

Create hk.pkl in project root. Always use version-pinned imports:

amends "package://github.com/jdx/hk/releases/download/v1.28.0/hk@1.28.0#/Config.pkl"
import "package://github.com/jdx/hk/releases/download/v1.28.0/hk@1.28.0#/Builtins.pkl"

local linters = new Mapping<String, Step> {
    // Add linters here based on project type
}

hooks {
    ["pre-commit"] {
        fix = true
        stash = "git"
        steps = linters
    }
    ["pre-push"] {
        steps = linters
    }
    ["fix"] {
        fix = true
        steps = linters
    }
    ["check"] {
        steps = linters
    }
}

4. Install & Test

hk validate       # Check config syntax
hk install        # Install git hooks
hk check --all    # Run all checks
hk fix --all      # Auto-fix issues

Project Templates

Python (ruff + ty)

local linters = new Mapping<String, Step> {
    ["ruff"] = Builtins.ruff
    ["ruff-format"] = Builtins.ruff_format
    ["ty"] {
        glob = "**/*.py"
        check = "ty check"
    }
    ["pkl"] = Builtins.pkl
}

JavaScript/TypeScript (eslint + prettier)

local linters = new Mapping<String, Step> {
    ["eslint"] = Builtins.eslint
    ["prettier"] = Builtins.prettier
    ["pkl"] = Builtins.pkl
}

JavaScript/TypeScript (biome)

Biome is a fast all-in-one linter+formatter. Use instead of eslint+prettier for new projects:

local linters = new Mapping<String, Step> {
    ["biome"] = Builtins.biome
    ["pkl"] = Builtins.pkl
}

JavaScript/TypeScript (oxc)

Oxlint + oxfmt from the oxc project. Oxfmt is alpha but very fast:

local linters = new Mapping<String, Step> {
    ["oxlint"] = Builtins.ox_lint
    ["oxfmt"] {
        glob = "**/*.{ts,tsx,js,jsx,json,md}"
        check = "oxfmt --check {{files}}"
        fix = "oxfmt {{files}}"
    }
    ["pkl"] = Builtins.pkl
}

Install: npm install -g oxfmt

Go

local linters = new Mapping<String, Step> {
    ["gofmt"] = Builtins.gofmt
    ["goimports"] = Builtins.goimports
    ["golangci-lint"] = Builtins.golangci_lint
    ["pkl"] = Builtins.pkl
}

Rust

local linters = new Mapping<String, Step> {
    ["rustfmt"] = Builtins.rustfmt
    ["clippy"] = Builtins.clippy
    ["pkl"] = Builtins.pkl
}

Swift (swiftlint + swiftformat)

local linters = new Mapping<String, Step> {
    ["swiftlint"] = Builtins.swiftlint
    ["swiftformat"] {
        glob = "**/*.swift"
        check = "swiftformat --lint {{files}}"
        fix = "swiftformat {{files}}"
    }
    ["pkl"] = Builtins.pkl
}

Shell

local linters = new Mapping<String, Step> {
    ["shellcheck"] = Builtins.shellcheck
    ["shfmt"] = Builtins.shfmt
    ["pkl"] = Builtins.pkl
}

Docker

local linters = new Mapping<String, Step> {
    ["hadolint"] = Builtins.hadolint
    ["pkl"] = Builtins.pkl
}

Universal Linters

These work for any project. Add them directly to your linters mapping:

local linters = new Mapping<String, Step> {
    // Language-specific linters...
    ["ruff"] = Builtins.ruff

    // Universal linters (add to any project)
    ["typos"] = Builtins.typos                             // Spell checker
    ["trailing-whitespace"] = Builtins.trailing_whitespace // Remove trailing spaces
    ["newlines"] = Builtins.newlines                       // Ensure final newline
}

Note: Pkl Mappings don't support + concatenation. Define all linters in a single mapping.

Other useful universal builtins:

• check_merge_conflict - Prevent committing merge conflict markers
• detect_private_key - Prevent committing private keys
• check_added_large_files - Warn about large files

Custom Steps

For tools without builtins, define custom steps:

["my-linter"] {
    glob = "**/*.ext"           // Files to match
    check = "my-tool check {{files}}"  // Check command
    fix = "my-tool fix {{files}}"      // Optional fix command
}

Step Options

Environment Variables

If tools are in a venv or non-standard location:

env {
    ["PATH"] = ".venv/bin:\(read("env:PATH"))"
}

Or better: install tools globally via brew/mise.

Troubleshooting

Tool not found

# Check if tool is in PATH
which ruff

# Install globally
brew install ruff
# or
mise use -g ruff

Config validation failed

hk validate
# Check Pkl syntax errors in output

Hooks not running

# Reinstall hooks
hk install

# Check hook files exist
ls -la .git/hooks/pre-commit

Examples

User asks to add pre-commit hooks

1. Check project type (look for pyproject.toml, package.json, etc.)
2. Check what tools are available (hk builtins, which ruff)
3. Create appropriate hk.pkl
4. Run hk validate && hk install
5. Test with hk check --all
6. Fix issues with hk fix --all

User has existing linter config

1. Read existing config (ruff.toml, .eslintrc, etc.)
2. Use matching hk builtins
3. Add any custom tools as custom steps