Event Reactor

What This Template Does

This template demonstrates the event → read → decide → write pattern using a LogTrigger for real-time on-chain reaction.

The workflow:

1. LogTrigger fires when MonitoredToken emits a LargeTransfer event
2. Decodes the event using typed bindings (from, to, amount, timestamp)
3. Reads ReactorConsumer state to check if the sender is already flagged
4. Decides: If not flagged, sends a signed report to flag the address on-chain. If already flagged, logs and skips.

Key Technologies:

• CRE (Chainlink Runtime Environment) — Event-driven workflow orchestration with DON consensus
• LogTrigger — Real-time event reaction without cron delays
• State-aware decisions — Checks existing state before acting to avoid duplicates

How It Works

Getting Started

cd my-workflow && bun install && cd .. && cd contracts && bun install && cd ..

cd my-workflow && bun test

cre workflow simulate my-workflow --target staging-settings \
  --non-interactive \
  --trigger-index 0 \
  --evm-tx-hash 0xe5ac97df3f93c5fdc89690a71d68a8e5ebd35ec8ba9c6cb5d1069f5818222553 \
  --evm-event-index 0

cast send 0x805A04e5C8b2dcb2B26C9e9C9aa12ce34374A35b \
  "simulateLargeTransfer(address,uint256)" \
  0x000000000000000000000000000000000000dEaD \
  2000000000000000000000

forge create src/MonitoredToken.sol:MonitoredToken \
  --broadcast --private-key <KEY> --rpc-url <RPC>

forge create src/ReactorConsumer.sol:ReactorConsumer \
  --broadcast --private-key <KEY> --rpc-url <RPC> \
  --constructor-args 0x15fc6ae953e024d975e77382eeec56a9101f9f88

Customization

• Change monitored event — Modify MonitoredToken or point to a different contract
• Change reaction logic — Update the onLargeTransfer workflow and _processReport in the contract
• Add off-chain API calls — Use cre.capabilities.HTTPClient to fetch external data before deciding

For full details, see the TypeScript README on GitHub.