This doesn't seem to happen with some "older" builds I have, but on master ... I'm seeing that if I edit
/etc/config/snmpd, then restart the snmpd service => it updates
/var/run/snmpd.conf (as was also noted here). But - the service itself seems to be making use of the configuration file
/etc/snmp/snmpd.conf (which is not updated when
/etc/config/snmpd is modified).
Anyone else seeing this? Is it just a recent change / bug?