feat: callback to intercept and modify predicates before re-registration

components/client/typescript/src/index.ts

@@ -6,6 +6,7 @@ import { Static, Type } from '@fastify/type-provider-typebox';
 import { BitcoinIfThisOptionsSchema, BitcoinIfThisSchema } from './schemas/bitcoin/if_this';
 import { StacksIfThisOptionsSchema, StacksIfThisSchema } from './schemas/stacks/if_this';
 import { logger } from './util/logger';
+import { PredicateSchema } from './schemas/predicate';
 
 const EventObserverOptionsSchema = Type.Object({
   /** Event observer host name (usually '0.0.0.0') */
@@ -40,6 +41,9 @@ const EventObserverOptionsSchema = Type.Object({
    * up to date. If they become obsolete, we will attempt to re-register them.
    */
   predicate_health_check_interval_ms: Type.Optional(Type.Integer({ default: 5000 })),
+  predicate_re_register_callback: Type.Optional(
+    Type.Function([PredicateSchema], Type.Promise(PredicateSchema))
+  ),
 });
 /** Chainhook event observer configuration options */
 export type EventObserverOptions = Static<typeof EventObserverOptionsSchema>;

components/client/typescript/src/predicates.ts

@@ -146,11 +146,15 @@ async function registerPredicate(
         authorization_header: `Bearer ${observer.auth_token}`,
       },
     };
-    const newPredicate = pendingPredicate as Predicate;
+    let newPredicate = pendingPredicate as Predicate;
     newPredicate.uuid = randomUUID();
     if (newPredicate.networks.mainnet) newPredicate.networks.mainnet.then_that = thenThat;
     if (newPredicate.networks.testnet) newPredicate.networks.testnet.then_that = thenThat;
 
+    if (observer.predicate_re_register_callback) {
+      newPredicate = await observer.predicate_re_register_callback(newPredicate);
+    }
+
     const path = observer.node_type === 'chainhook' ? `/v1/chainhooks` : `/v1/observers`;
     await request(`${chainhook.base_url}${path}`, {
       method: 'POST',