# DX Tooling - Bulletproof Local-First Developer Experience
## Goal
Replace scattered tooling with a fast, automated, local-first DX stack that catches issues before they reach the repo.
## Tools
### Added
| Tool | Purpose | Runs at |
|------|---------|---------|
| Biome | Lint + format (replaces ESLint + Prettier) | Pre-commit |
| Lefthook | Git hooks with parallel execution | Pre-commit, pre-push |
| Gitleaks | Secret scanning | Pre-commit |
| Knip | Dead code and unused dependency detection | Pre-commit |
| publint | Package.json validation for npm | Pre-push |
| Renovate | Automated dependency updates | Weekly (GitHub) |
### Removed
| Tool | Replaced by |
|------|-------------|
| eslint | Biome |
| @typescript-eslint/parser | Biome |
| @typescript-eslint/eslint-plugin | Biome |
| eslint-config-prettier | Biome |
| prettier | Biome |
| eslint.config.js | biome.json |
## Local Flow
```
git commit -> Lefthook pre-commit (parallel):
├── Biome check --write (format + lint + autofix)
├── tsc --noEmit (type check)
├── Gitleaks protect --staged (secret scan)
└── Knip (dead code check)
git push -> Lefthook pre-push (parallel):
├── Vitest run (full test suite)
└── publint (package validation)
```
## Config Files
### lefthook.yml
```yaml
pre-commit:
parallel: true
commands:
biome:
glob: "*.{ts,js,json}"
run: biome check --write {staged_files} && git add {staged_files}
typecheck:
run: tsc --noEmit
gitleaks:
run: gitleaks protect --staged --no-banner
knip:
run: knip --no-progress
pre-push:
parallel: true
commands:
test:
run: vitest run
publint:
run: publint
```
### biome.json
Migrate from current ESLint + Prettier config. Use `biome migrate` to auto-convert.
### .gitleaks.toml
```toml
[extend]
useDefault = true
[allowlist]
paths = [
"node_modules",
".env.example"
]
```
### renovate.json
```json
{
"$schema": "https://docs.renovatebot.com/renovate-schema.json",
"extends": [
"config:recommended",
":automergeMinor",
":semanticCommits",
"group:allNonMajor"
],
"schedule": ["before 9am on monday"],
"vulnerabilityAlerts": {
"enabled": true,
"labels": ["security"]
}
}
```
## Implementation Steps
1. Install Biome, migrate config, remove ESLint + Prettier
2. Install Lefthook, create `lefthook.yml`
3. Install Gitleaks (brew), add `.gitleaks.toml`
4. Install Knip + publint
5. Add `renovate.json` to repo
6. Update CI workflow to match local tooling
7. Update package.json scripts
