# quicproquo SDK Documentation

This guide covers how to build clients for the quicproquo E2E encrypted messenger using the official SDKs or by implementing your own.

## Official SDKs

| Language | Location | Transport | Status |
|---|---|---|---|
| **Rust** | `crates/quicproquo-client` | QUIC + Cap'n Proto | Production |
| **Go** | `sdks/go/` | QUIC + Cap'n Proto | Production |
| **TypeScript** | `sdks/typescript/` | WebSocket bridge + WASM crypto | Production |
| **Python** | `sdks/python/` | QUIC + Protobuf (v2) / Rust FFI | Production |
| **C** | `crates/quicproquo-ffi/` | Rust FFI (synchronous) | Production |
| **Swift** | `sdks/swift/` | C FFI wrapper | In progress |
| **Kotlin** | `sdks/kotlin/` | JNI + C FFI | In progress |
| **Java** | `sdks/java/` | JNI + C FFI | In progress |
| **Ruby** | `sdks/ruby/` | FFI gem | In progress |

## Documentation

- [Wire Format](wire-format.md) -- v2 QUIC + Protobuf wire protocol
- [Rust SDK](rust.md) -- Native Rust client
- [Go SDK](go.md) -- Go client with QUIC transport
- [Python SDK](python.md) -- Python client (async QUIC + sync FFI)
- [TypeScript SDK](typescript.md) -- Browser/Node.js client with WASM crypto
- [C FFI](c-ffi.md) -- C bindings for language integrations
- [Build Your Own SDK](build-your-own.md) -- Guide for implementing a new language SDK

## Architecture Overview

```
  Client SDK                     Server
  ─────────                     ──────
  ┌──────────┐   QUIC/TLS 1.3   ┌──────────┐
  │ App code │ ◄──────────────► │ RPC      │
  │          │   v2 wire frames  │ dispatch │
  │ SDK API  │                   │          │
  │          │   [method_id:u16] │ handlers │
  │ Proto    │   [req_id:u32]    │          │
  │ encode/  │   [len:u32]       │ storage  │
  │ decode   │   [protobuf]      │          │
  │          │                   │          │
  │ QUIC     │                   │ QUIC     │
  │ transport│                   │ listener │
  └──────────┘                   └──────────┘
```

Each RPC call opens a new QUIC bidirectional stream. The request and response use the same 10-byte framing header followed by a protobuf payload.

## Quick Start

1. Choose an SDK for your language
2. Connect to the server over QUIC (or WebSocket bridge for browsers)
3. Authenticate with OPAQUE (register or login)
4. Upload MLS key packages for E2E encryption
5. Send and receive encrypted messages

## Canonical Schemas

- **Protobuf** (v2): `proto/qpq/v1/*.proto` -- 14 service definitions
- **Cap'n Proto** (v1): `schemas/*.capnp` -- legacy RPC interface

The protobuf schemas in `proto/qpq/v1/` are the canonical API contract for the v2 protocol. New SDKs should implement against these definitions.
