Analyze existing repositories, maintain structure, setup guardrails and best practices
Load with: base.md + security.md
For working with existing codebases - analyze structure, respect conventions, and set up proper guardrails without breaking anything.
Sources: Husky | lint-staged | pre-commit | commitlint
Understand before modifying. Existing repos have conventions, patterns, and history. Your job is to work within them, not reorganize them.
ALWAYS run this analysis first when joining an existing repo.
# Check git status
git remote -v 2>/dev/null
git branch -a 2>/dev/null
git log --oneline -5 2>/dev/null
# Check for existing configs
ls -la .* 2>/dev/null | head -20
ls *.json *.toml *.yaml *.yml 2>/dev/null# JavaScript/TypeScript
ls package.json tsconfig.json 2>/dev/null
# Python
ls pyproject.toml setup.py requirements*.txt 2>/dev/null
# Mobile
ls pubspec.yaml 2>/dev/null # Flutter
ls android/build.gradle 2>/dev/null # Android
ls ios/*.xcodeproj 2>/dev/null # iOS
# Other
ls Cargo.toml 2>/dev/null # Rust
ls go.mod 2>/dev/null # Go
ls Gemfile 2>/dev/null # Ruby| Pattern | Detection | Meaning |
|---|---|---|
| Monorepo | packages/, apps/, workspaces in package.json | Multiple projects, shared tooling |
| Full-Stack Monolith | frontend/ + backend/ in same repo | Single team, tightly coupled |
| Separate Concerns | Only frontend OR backend code | Split repos, separate deploys |
| Microservices | Multiple service-* or domain dirs | Distributed architecture |
# Detect repo structure type
if [ -d "packages" ] || [ -d "apps" ]; then
echo "MONOREPO detected"
elif [ -d "frontend" ] && [ -d "backend" ]; then
echo "FULL-STACK MONOLITH detected"
elif [ -d "src" ] || [ -d "app" ]; then
# Check if it's frontend or backend
grep -q "react\|vue\|angular" package.json 2>/dev/null && echo "FRONTEND detected"
grep -q "fastapi\|express\|django" package.json pyproject.toml 2>/dev/null && echo "BACKEND detected"
fi# Get directory structure (max 3 levels)
find . -type d -maxdepth 3 \
-not -path "*/node_modules/*" \
-not -path "*/.git/*" \
-not -path "*/venv/*" \
-not -path "*/__pycache__/*" \
-not -path "*/dist/*" \
-not -path "*/build/*" \
2>/dev/null | head -50
# Identify key directories
for dir in src app lib core services api routes components pages hooks utils models; do
[ -d "$dir" ] && echo "Found: $dir/"
done# Find main entry points
ls index.ts index.js main.ts main.py app.py server.ts server.js 2>/dev/null
cat package.json 2>/dev/null | grep -A1 '"main"'
cat pyproject.toml 2>/dev/null | grep -A1 'scripts'Identify and document existing patterns before making changes.
# Check for formatters
ls .prettierrc* .editorconfig .eslintrc* biome.json 2>/dev/null # JS/TS
ls pyproject.toml | xargs grep -l "ruff\|black\|isort" 2>/dev/null # Python
# Check indent style from existing files
head -20 src/**/*.ts 2>/dev/null | grep "^\s" | head -1 # tabs vs spaces# JS/TS testing
grep -l "jest\|vitest\|mocha\|playwright" package.json 2>/dev/null
ls jest.config.* vitest.config.* playwright.config.* 2>/dev/null
# Python testing
grep -l "pytest\|unittest" pyproject.toml 2>/dev/null
ls pytest.ini conftest.py 2>/dev/null
# Test directories
ls -d tests/ test/ __tests__/ spec/ 2>/dev/null# Check existing workflows
ls -la .github/workflows/ 2>/dev/null
ls .gitlab-ci.yml Jenkinsfile .circleci/ 2>/dev/null
# Check deploy configs
ls vercel.json render.yaml fly.toml railway.json Dockerfile 2>/dev/null# Find README pattern
head -30 README.md 2>/dev/null
# Find existing docs
ls -la docs/ documentation/ wiki/ 2>/dev/null
ls CONTRIBUTING.md CHANGELOG.md 2>/dev/nullCheck what guardrails exist and what's missing.
# Check for hook managers
ls .husky/ 2>/dev/null && echo "Husky installed"
ls .pre-commit-config.yaml 2>/dev/null && echo "pre-commit framework installed"
ls .git/hooks/pre-commit 2>/dev/null && echo "Manual pre-commit hook exists"
# Check what hooks run
cat .husky/pre-commit 2>/dev/null
cat .pre-commit-config.yaml 2>/dev/null# JS/TS linting
grep -q "eslint" package.json && echo "ESLint configured"
grep -q "biome" package.json && echo "Biome configured"
ls .eslintrc* biome.json 2>/dev/null
# Python linting
grep -q "ruff" pyproject.toml && echo "Ruff configured"
grep -q "flake8" pyproject.toml setup.cfg && echo "Flake8 configured"# TypeScript
ls tsconfig.json 2>/dev/null && echo "TypeScript configured"
grep "strict" tsconfig.json 2>/dev/null
# Python type checking
grep -q "mypy" pyproject.toml && echo "mypy configured"
grep -q "pyright" pyproject.toml && echo "pyright configured"
ls py.typed 2>/dev/null# commitlint
ls commitlint.config.* 2>/dev/null && echo "commitlint configured"
cat .husky/commit-msg 2>/dev/null
grep "conventional" package.json 2>/dev/null# Check for security tools
grep -q "detect-secrets\|trufflehog" .pre-commit-config.yaml package.json 2>/dev/null
ls .github/workflows/*.yml | xargs grep -l "security\|audit" 2>/dev/nullOnly add missing guardrails. Never overwrite existing configurations.
# Check if already installed
if [ ! -d ".husky" ]; then
# Install Husky
npm install -D husky lint-staged
npx husky init
# Create pre-commit hook
echo 'npx lint-staged' > .husky/pre-commit
chmod +x .husky/pre-commit
filint-staged config (add to package.json if missing):
{
"lint-staged": {
"*.{ts,tsx,js,jsx}": [
"eslint --fix",
"prettier --write"
],
"*.{json,md,yml,yaml}": [
"prettier --write"
]
}
}# Check if eslint exists
if ! grep -q "eslint" package.json; then
npm install -D eslint @typescript-eslint/parser @typescript-eslint/eslint-plugin
fieslint.config.js (ESLint 9+ flat config):
import eslint from '@eslint/js'
import tseslint from 'typescript-eslint'
export default tseslint.config(
eslint.configs.recommended,
...tseslint.configs.recommended,
{
rules: {
'@typescript-eslint/no-unused-vars': ['error', { argsIgnorePattern: '^_' }],
'@typescript-eslint/explicit-function-return-type': 'off',
'no-console': ['warn', { allow: ['warn', 'error'] }]
}
},
{
ignores: ['dist/', 'node_modules/', 'coverage/']
}
)if ! grep -q "prettier" package.json; then
npm install -D prettier
fi.prettierrc (respect existing style or use sensible defaults):
{
"semi": false,
"singleQuote": true,
"trailingComma": "es5",
"tabWidth": 2,
"printWidth": 100
}if [ ! -f "commitlint.config.js" ]; then
npm install -D @commitlint/cli @commitlint/config-conventional
echo "npx commitlint --edit \$1" > .husky/commit-msg
chmod +x .husky/commit-msg
ficommitlint.config.js:
export default {
extends: ['@commitlint/config-conventional'],
rules: {
'type-enum': [
2,
'always',
['feat', 'fix', 'docs', 'style', 'refactor', 'test', 'chore', 'ci', 'perf', 'revert']
],
'subject-case': [2, 'always', 'lower-case'],
'subject-max-length': [2, 'always', 72]
}
}# Install pre-commit
if [ ! -f ".pre-commit-config.yaml" ]; then
pip install pre-commit
pre-commit install
fi.pre-commit-config.yaml:
repos:
# Ruff - linting and formatting (replaces black, isort, flake8)
- repo: https://github.com/astral-sh/ruff-pre-commit
rev: v0.14.13
hooks:
- id: ruff
args: [--fix, --exit-non-zero-on-fix]
- id: ruff-format
# Type checking
- repo: https://github.com/pre-commit/mirrors-mypy
rev: v1.16.0
hooks:
- id: mypy
additional_dependencies: [types-requests]
args: [--ignore-missing-imports]
# Security
- repo: https://github.com/Yelp/detect-secrets
rev: v1.5.0
hooks:
- id: detect-secrets
args: ['--baseline', '.secrets.baseline']
# General
- repo: https://github.com/pre-commit/pre-commit-hooks
rev: v5.0.0
hooks:
- id: trailing-whitespace
- id: end-of-file-fixer
- id: check-yaml
- id: check-added-large-files
- id: check-merge-conflict
# Commit messages
- repo: https://github.com/compilerla/conventional-pre-commit
rev: v4.0.0
hooks:
- id: conventional-pre-commit
stages: [commit-msg][tool.ruff]
target-version = "py312"
line-length = 100
[tool.ruff.lint]
select = [
"E", # pycodestyle errors
"F", # pyflakes
"I", # isort
"B", # flake8-bugbear
"UP", # pyupgrade
"S", # flake8-bandit (security)
]
ignore = ["E501"] # line length handled by formatter
[tool.mypy]
python_version = "3.12"
strict = true
ignore_missing_imports = true
[tool.pytest.ini_options]
testpaths = ["tests"]
addopts = "-v --cov=src --cov-report=term-missing --cov-fail-under=80"Recommend these GitHub branch protection rules:
## Recommended Branch Protection (main branch)
1. **Require pull request before merging**
- Require 1 approval
- Dismiss stale reviews on new commits
2. **Require status checks**
- Lint
- Type check
- Tests
- Security scan
3. **Require signed commits** (optional but recommended)
4. **Do not allow bypassing above settings**Before writing any code, identify:
| Convention | Example | Where to Check |
|---|---|---|
| Naming | camelCase vs snake_case | Existing file names |
| File structure | feature/ vs type/ | Directory layout |
| Export style | default vs named | Existing modules |
| Error handling | throw vs return Error | Existing functions |
| Logging | console vs logger | Existing code |
| Testing | describe/it vs test() | Existing tests |
| Comments | JSDoc vs inline | Existing code |
After running analysis, generate this report:
# Repository Analysis Report
## Overview
- **Repo Type**: [Monorepo | Full-Stack | Frontend | Backend | Microservices]
- **Primary Language**: [TypeScript | Python | ...]
- **Framework**: [React | FastAPI | ...]
- **Age**: [X commits, Y contributors]
## Directory Structure[tree output]
## Tech Stack
| Category | Technology | Config File |
|----------|------------|-------------|
| Language | TypeScript | tsconfig.json |
| Framework | React | - |
| Testing | Vitest | vitest.config.ts |
| Linting | ESLint | eslint.config.js |
| Formatting | Prettier | .prettierrc |
## Guardrails Status
### Present
- [x] ESLint configured
- [x] Prettier configured
- [x] TypeScript strict mode
### Missing (Recommended)
- [ ] Pre-commit hooks (Husky + lint-staged)
- [ ] Commit message validation (commitlint)
- [ ] Security scanning in CI
## Conventions Detected
| Pattern | Observed | Example |
|---------|----------|---------|
| Naming | camelCase | `getUserById.ts` |
| Imports | Absolute | `@/components/Button` |
| Testing | Colocated | `Button.test.tsx` |
| Exports | Named | `export { Button }` |
## Recommendations
1. Add Husky + lint-staged for pre-commit hooks
2. Add commitlint for conventional commits
3. Add security workflow to GitHub Actions
## Files to Review First
- `src/index.ts` - Main entry point
- `src/utils/` - Shared utilities
- `tests/setup.ts` - Test configurationDon't add all guardrails at once. Follow this timeline:
| Week | Focus | Why |
|---|---|---|
| 1 | Formatting (Prettier/Ruff) | Non-breaking, easy wins |
| 2 | Linting (ESLint/Ruff) | Catches obvious issues |
| 3 | Pre-commit hooks | Automates week 1-2 |
| 4 | Commit message validation | Team consistency |
| 5 | Type checking strictness | Catches runtime errors |
| 6 | Security scanning | Catches vulnerabilities |
When frontend and backend are in separate repos:
# Clone and analyze
git clone [frontend-repo]
cd frontend
# Run analysis
# Expect: React/Vue/Angular, no backend code
# Add frontend-specific guardrails
# - Husky + lint-staged
# - ESLint + Prettier
# - Component testing (Vitest/Jest)# Clone and analyze
git clone [backend-repo]
cd backend
# Run analysis
# Expect: FastAPI/Express/Django, no frontend code
# Add backend-specific guardrails
# - pre-commit framework
# - Ruff + mypy
# - API testing (pytest/Jest)| Concern | Solution |
|---|---|
| Shared types | Generate from OpenAPI spec |
| API contracts | Contract testing (Pact) |
| Deployments | Coordinate via CI/CD triggers |
| Versioning | Semantic versioning on both |
# One-liner repo analysis
echo "=== Repo Type ===" && \
ls -d packages apps frontend backend 2>/dev/null || echo "Standard repo" && \
echo "=== Tech Stack ===" && \
ls *.json *.toml *.yaml 2>/dev/null && \
echo "=== Existing Guardrails ===" && \
ls .husky .pre-commit-config.yaml .eslintrc* 2>/dev/null || echo "None detected" && \
echo "=== Entry Points ===" && \
ls index.* main.* app.* server.* 2>/dev/nulld4ddb03
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