rsc_update

Resource update helper module used by m_rsc.

This module contains insert/update/delete/merge routines for resources and is logically part of the m_rsc model implementation. It is not exposed as a standalone model path endpoint.

Resource insert/update MQTT events include version, previous_version and reason. Background media workers can pass the update option {update_reason, media_processing}. The reason is media_processing only if that resource's properties are unchanged apart from version, modified and modifier_id; otherwise it is update. Clients must still check consecutive versions before acknowledging processing updates on an unsaved form. Menu saves can pass {update_reason, menu}; this reason is preserved only when no properties other than menu and the modification metadata changed. Derived pivot_* fields and absent versus undefined values are ignored for both reasons.