# Watchers The watcher observes the Updater's interactions with the Home contract (by watching the Home contract) and reacts to malicious or faulty attestations. It also observes any number of replicas to ensure the Updater does not bypass the Home and go straight to a replica. **It is an off-chain actor that does the following:** * Observe the home * Observe 1 or more replicas * Maintain a DB of seen updates * Submit double-update proofs * Submit invalid update proofs * If configured, issue an emergency halt transaction --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.nomad.xyz/the-nomad-protocol/off-chain-agents/watchers.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.