Continuum

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Continuum solves one of the hardest problems in rollup development: how do users carry their state forward when aztec rollup upgrades

What Problem Continuum Solves

When an Aztec L2 rollup migrates to a new version, all on-chain state is reset. Users who held NFTs, tokens, or other assets on the old rollup need a way to prove those holdings and recreate them on the new rollup — without trusting any single party and without requiring access to the old rollup's private data.

Continuum provides a cryptographic bridge between old and new rollup state using:

• An event indexer that reads public events from the old rollup
• An attester service that signs user state claims with a Schnorr key
• A Noir smart contract on the new rollup that verifies those signatures and records the migration

Architecture

Continuum is made of three off-chain services and a set of Noir contracts:

• MongoDB stores indexed events, sync cursors, contract ABIs, and old→new collection mappings.
• Indexer polls the old rollup’s Aztec node for public events and writes them to MongoDB.
• Fastify API exposes admin and public endpoints; it signs migration claims with a Schnorr attester key.
• Noir contracts live on both rollups. The old collection emits ownership and registration events; the new collection verifies Continuum’s attestation and mints the migrated asset.

Migration Flow

1. Register contracts: upload the old collection ABI to the API and register the old→new collection address mapping.
2. Create a migration secret: the user calls /migration/new-secret and saves the secret.
3. Register the commitment on the old rollup: the user calls MigrationRegistry.register_migration(collection, commitment) (or the NFT contract’s own registration function), where commitment = Poseidon2("NFTMR" ‖ secret).
4. Index events:the indexer crawls the old rollup and stores Transfer and MigrationRegistered events.
5. Request signed claim data: the user reveals the secret to /request_data; the API recomputes the commitment, resolves the verified owner, and returns Schnorr-signed attestations for each owned token.
6. Claim on the new rollup:the user calls newNFT.migrate_and_claim(token_id, commitment, signature), which verifies the signature and mints the token.

For a complete step-by-step example, see e2e-tests/src/sandbox/index.ts. For a recent testnet run, see e2e-tests/src/testnet/run_logs_july_1.txt.

Quick Start

Prerequisites

• Docker and Docker Compose
• Bun or Node.js for local development

Running with Docker Compose

1. Clone the repository

   git clone git@github.com:raven-house/continuum.git
   cd continuum

2. Configure environment

   cp .env.example .env

   If trying on Aztec Sandbox, download Aztec CLI from https://docs.aztec.network/developers/getting_started_on_local_network and start sandbox using aztec start --local-network

   Set AZTEC_NETWORK=sandbox in .env file

3. Start all services

   docker compose up -d

   This starts:

   • MongoDB on port 27017
   • Event Indexer (background service)
   • REST API on port 3004

4. Register contracts for indexing

   Upload each Aztec contract ABI through the API. The API extracts event selectors and stores the indexing configuration in MongoDB for the indexer.

   curl -X POST http://localhost:3004/contracts/upload \
     -H "Content-Type: application/json" \
     -d '{
       "artifact_id": "my-contract",
       "name": "My Contract",
       "abi": { /* Noir ABI JSON */ },
       "enabled": true,
       "event_types": ["Transfer", "Mint"],
       "start_block": {
         "testnet": 5000,
         "sandbox": 0
       }
     }'

   Omit event_types or pass an empty array to index all events in the ABI.

5. Check service status

   docker compose ps

6. View logs

   # All services
   docker compose logs -f
   
   # Specific service
   docker compose logs -f indexer
   docker compose logs -f api
   docker compose logs -f mongodb

7. Stop services

docker compose down

To also remove the MongoDB volume (WARNING: deletes all data):

docker compose down -v

List all docker volumes

docker volume ls

Development

Live Reload (no rebuild on code changes)

docker-compose.yml is the default local development stack. It mounts the source files as volumes so changes are reflected without rebuilding.

# First time — build images to bake in dependencies
docker compose up -d --build

# After any code change — just restart, no rebuild
docker compose up -d

# Only rebuild when adding/removing npm packages
docker compose up -d --build

# Run contract test cases
aztec test

Production deploy

In production, explicitly use the production compose file so self-contained built images are used and source code is not mounted from the host:

docker compose -f docker-compose.prod.yml up -d

API Endpoints

All endpoints are on port 3004.

Available Endpoints

Method	Path	Purpose
GET	/health	API liveness
POST	/contracts/upload	Upload ABI and indexing config (admin)
GET	/contracts / /contracts/:id / /contracts/event/:selector	Query uploaded contracts
POST	/collections/register	Map old→new collection address (admin)
GET	/collections / /collections/:newAddress	List / lookup mappings
GET	/migration/new-secret	Generate migration secret + commitment
POST	/migration/commitment	Recompute commitment from secret
POST	/request_data	Request signed token attestations
GET	/attester	Get the attester public key

Contract ABI Upload

# Upload contract ABI and extract events with selectors
curl -X POST http://localhost:3004/contracts/upload \
  -H "Content-Type: application/json" \
  -d '{
    "artifact_id": "my-contract",
    "name": "MyContract",
    "abi": { /* Noir ABI JSON */ },
    "enabled": true,
    "event_types": ["Transfer"],
    "start_block": {
      "testnet": 5000,
      "sandbox": 0
    }
  }'

# List all uploaded contracts
curl "http://localhost:3004/contracts?page=1&limit=10"

# Get specific contract by ID
curl http://localhost:3004/contracts/<contract-id>

# Find event by selector
curl http://localhost:3004/contracts/event/0x12345678

Troubleshooting

Indexer Not Processing Events

# Check indexer logs
docker compose logs -f indexer

# Verify registered contracts
curl "http://localhost:3004/contracts?page=1&limit=10"

# Check indexer health (inside the indexer container)
curl http://localhost:8080/health

API Not Responding

# Check API logs
docker compose logs -f api

# Verify API is running
curl http://localhost:3004/health

Run NFT Contract Tests

nft_contract tests need the compiled generic_proxy artifact in their target folder:

cd contracts/generic_proxy
aztec-nargo compile
cp target/generic_proxy-GenericProxy.json ../nft_contract/target/
cd ../nft_contract
aztec test

Address of Migration registry contract on testnet version 5.0.0-rc2 is 0x0f10ac27189276a91039bd47317783b1f76ce2fa1f26b89be1df464c08a5b3b3

License

MIT

Contributing

Contributions are welcome! Please open an issue or pull request.