Currently if a host gets decomissioned the zabbix-host get nodata/agent.ping fails and the items are stuck in queues.
We solve that currently with a hostmetadata entry ("dereg") and and agent service restart to transmit this metadata. On the zabbix server we have an Auto registration action which then disables the host.
It would be great, if the agent would send the server a signal if it gets uninstalled. In the frontend we would also need an Configuration > Actions > Event source: Auto deregistration where we then can define actions to decide what has to be done.
If the agent is reinstalled later the autoregistration could again trigger the configured actions for this scenario.