# RailBridge Composer Implementation Summary

## Completed Components

### Smart Contracts
- ✅ `PacketRegistry.sol` - On-chain packet lifecycle registry
- ✅ `IPacketRegistry.sol` - Interface for packet registry

### Core Modules
- ✅ Instruction types and data models
- ✅ Composer engine (orchestrates PDF generation, signing, packaging)
- ✅ Instruction validator
- ✅ Sidecar file generator (JSON, XML, hashes)

### PDF Generation
- ✅ PDF generator using PDFKit
- ✅ PDF layout utilities (cover page, MT103 fields, signatures, appendix)
- ✅ QR code generation for verification
- ✅ PDF signing module (PAdES support)

### Templates
- ✅ Template engine (Handlebars)
- ✅ MT103-equivalent credit transfer template
- ✅ Recall/cancellation template
- ✅ Return/reject template
- ✅ Settlement confirmation template

### Crypto & Security
- ✅ Hashing (SHA-256, SHA3-256)
- ✅ PGP encryption
- ✅ S/MIME encryption

### Transport Modules
- ✅ Secure email transport (PGP + S/MIME)
- ✅ AS4 envelope builder
- ✅ Portal upload handler

### Chain Integration
- ✅ ChainID 138 connector
- ✅ Trigger registry client
- ✅ Packet registry client

### Storage
- ✅ Counterparty profile store
- ✅ Key/certificate management

### Interfaces
- ✅ CLI interface (compose, send, verify, profile management)
- ✅ REST API service (Express)

## Configuration

Configuration is managed via `config/default.json` and environment variables:
- `RPC_URL` - ChainID 138 RPC endpoint
- `PRIVATE_KEY` - Private key for signing transactions
- `PACKET_REGISTRY` - PacketRegistry contract address
- `TRIGGER_REGISTRY` - RailTriggerRegistry contract address

## Usage

### CLI
```bash
# Compose packet from trigger
rbc compose <triggerId>

# Send packet
rbc send <instructionId> --mode email --profile <profileId>

# Verify packet
rbc verify <instructionId>

# List profiles
rbc profile list
```

### API
```bash
# Start API server
npm run start:api

# Compose packet
POST /api/v1/compose
{
  "triggerId": 12345
}

# Send packet
POST /api/v1/send
{
  "instructionId": "ABC-2025-000001",
  "mode": "email",
  "profileId": "counterparty1"
}
```

## Next Steps

1. Deploy `PacketRegistry` contract to ChainID 138
2. Configure contract addresses in `config/default.json`
3. Set up counterparty profiles
4. Test end-to-end flow
5. Add production email/AS4 integrations (currently placeholders)

## Notes

- Some transport modules contain placeholder implementations that need production integration
- PDF signing uses simplified PAdES (full implementation may require additional libraries)
- AS4 XML signing is simplified (full XMLDSig implementation needed for production)