# CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

## Project Overview

Metacrypt is a cryptographic service for the Metacircular platform, written in Go. It provides cryptographic resources via an "engines" architecture (CA, SSH CA, transit encryption, user-to-user encryption). Authentication is handled by MCIAS (Metacircular Identity and Access Service) using the client library at `git.wntrmute.dev/mc/mcias/clients/go`. MCIAS API docs: https://mcias.metacircular.net:8443/docs

## Build & Test Commands

```bash
go build ./...    # Build all packages
go test ./...     # Run all tests
go vet ./...      # Static analysis
```

## Architecture

- **Engines**: Modular cryptographic service providers (CA, SSH CA, transit, user-to-user encryption)
- **Storage**: SQLite database with an encrypted storage barrier (similar to HashiCorp Vault)
- **Seal/Unseal**: Single password unseals the service; a master encryption key serves as a key-encryption key (KEK) to decrypt per-engine data encryption keys
- **Auth**: MCIAS integration; MCIAS admin users get admin privileges on this service

## Project Structure

```
.
├── cmd/metacrypt/          # CLI entry point (server, init, status, snapshot)
├── deploy/
│   ├── docker/             # Docker Compose configuration
│   ├── examples/           # Example config files
│   ├── scripts/            # Deployment scripts
│   └── systemd/            # systemd unit files
├── internal/
│   ├── auth/               # MCIAS token authentication & caching
│   ├── barrier/            # Encrypted key-value storage abstraction
│   ├── config/             # TOML configuration loading & validation
│   ├── crypto/             # Low-level cryptographic primitives
│   ├── db/                 # SQLite setup & schema migrations
│   ├── engine/             # Pluggable engine registry & interface
│   ├── policy/             # Priority-based ACL engine
│   ├── seal/               # Seal/unseal state machine
│   └── server/             # HTTP server, routes, middleware
├── proto/metacrypt/        # Protobuf/gRPC definitions
├── web/
│   ├── static/             # CSS, HTMX
│   └── templates/          # Go HTML templates
├── Dockerfile
├── Makefile
└── metacrypt.toml.example
```

## Ignored Directories

- `srv/` — Local runtime data (database, certs, config). Do not read, modify, or reference these files.

## API Sync Rule

The gRPC proto definitions (`proto/metacrypt/v1/`) and the REST API (`internal/server/routes.go`) must always be kept in sync. When adding, removing, or changing an endpoint in either surface, the other must be updated in the same change. Every REST endpoint must have a corresponding gRPC RPC (and vice versa), with matching request/response fields.
