Each AI NPC will have their own diary. The purpose of this is to provide a roleplaying tool that can generate an after-action-report of your entire Skyrim playthrough!
We mainly intend that your followers are the main NPCs who keep diaries. As they are around you the most and have the most intresting stories to tell based from their adventures with you.
We highly recommend that you maintain diary entries for at least 1-2 followers as it's honestly very neat seeing the tale of your adventures from their perspective.
It will use a non-JSON connector (CONNECTORS_DIARY) to generate a diary entry.
Diaries can be triggered in 2 ways.

Diary entries are logged as memories, so they will be used to create summarized memory entries.
When looking for memories, it won't search in the diary directly, but info from diary entries are used to create memories summaries.
CHIM supports a memory system that will allow AI NPC’s to remember events that have happened in the past.
Memory Systems:
Auto Summaries - Long term system that generates summaries of events and pulls them into conversations when appropriate.
Midterm Memory - A list of previous events tracked for each NPC. Think of it as a "Dwarf Fortress" announcement list.
Dynamic Profiles - Short term changes and goals. These are updates to an NPC's biography fields.
You can configure how often it triggers in the MCM menu.
You can configure which fields are updated in the profile menu.
Diaries - Journal entries recording your adventures from other NPC's perspective.