PredicateHealthCheck re-register bug

[zone117x]

The chainhook client healthcheck code detects inactive predicates, and re-registers using the same predicate from when the app was started.

This causes chainhook to re-send old events starting at the block_height that the client specified on startup.

async function startChainhookServer() {
  const blockHeight = await db.getChainTipBlockHeight();
  const predicate = {
    name: 'metadata-api-blocks',
    version: 1,
    chain: 'stacks',
    networks: {
      mainnet: {
        start_block: blockHeight, // <-- predicate re-registration uses whatever this value was on app start
        include_contract_abi: true,
        if_this: {
          scope: 'block_height',
          higher_than: 1,
        },
      },
    },
  };
  const observer: EventObserverOptions = {
    predicate_health_check_interval_ms: 300_000,
    // ...
  };
  const server = new ChainhookEventObserver(observer, { ... });
  await server.start([predicate], payload => db.processPayload(payload));
}

This could be solved with something like a callback where the client can provide an updated predicate for re-registration. E.g.:

  const observer: EventObserverOptions = {
    predicate_health_check_interval_ms: 300_000,
    predicate_reregister_callback: async (predicate) => {
      predicate.networks.mainnet.start_block = await db.getChainTipBlockHeight();
      return predicate;
    },
  };