What are all these records that Message is creating?

Like any managed package, Modern Campus Message uses a number of records to store information about your configuration and make things work as expected. See below for a UML diagram and description of each record that Message uses.

SV Program (svmessaging__Signal_Vine_Program__c)
Contains metadata and configuration for each program.

Signal Vine Participant (svmessaging__Signal_Vine_Participant__c)
Contains metadata about records that are being shared/synced with Message. This creates an index of all records that the package syncs with or is available to message.

Message (svmessaging__Message__c)
Locally stores each incoming and outgoing message when that feature is enabled for a program.

Master Field Mapping (svmessaging__Master_Field_Mapping__c)
Contains field mapping configuration for each field in a program.

Change Log Entry (svmessaging__Change_Log_Entry__c)
Field history record used for bi-directional syncing, used to compare and determine which platform has the most recent data..

Log (svmessaging__Log__c)
This object is used to log as the batch job/API process and capturing any issues that arise.

Signal Vine Sync Object (svmessaging__Signal_Vine_Sync_Object__c)
Creates a queue of records that need to sync. These records are cleared once the sync is completed.

Signal Vine Participant Sync Object (svmessaging__Signal_Vine_Participant_Sync_Object__c)
This object is created via Flows or Process Builder to generate a new svmessaging__Signal_Vine_Participant__c record and trigger any additional processes that need to be completed by the package

Signal Vine Trigger Object (svmessaging__Signal_Vine_Trigger_Object__c)
This object creates a trigger when a svmessaging__Signal_Vine_Participant__c record is created for a record that is not a Contact.

Signal Vine Message Template (svmessaging__Signal_Vine_Message_Template__c)
This object stores the message templates for the program.

Signal Vine Program Permission (svmessaging__Signal_Vine_Program_Permission__c)
This object holds the program permissions that determine the user's visibility.

SV User Preferences (svmessaging__SV_User_Preference__c)
This object stores the user's notification preferences.

Signal Vine Message Search Save (svmessaging__Signal_Vine_Message_Search_Save__c)
This object holds a user's saved filters.

SV Quick Message (svmessaging__SV_Quick_Message__c)
No longer in use.