Settings system

The settings system is small but central: it stores user preferences and serves as the app’s change-notification hub. See State and history for the latter role.

Architecture

ISettingsService (Core) is implemented by SettingsService (Mnemo.Infrastructure/Services/SettingsService.cs). It keeps a ConcurrentDictionary cache in front of the SQLite Storage table, where each setting is its own row keyed by a dotted name like Appearance.Theme. Values are JSON-serialized, so settings can be any serializable type. Every SetAsync raises SettingChanged, which is subscribed throughout the app.

There is no settings schema or registry; a setting exists once some code reads or writes its key. Defaults live at the call sites.

Key namespaces

Prefix	Examples
User.	DisplayName, ProfilePicture
App.	Language, LaunchAtStartup, EnableGamification, DeveloperMode, Icon
Editor.	AutoSave, SpellCheck, SpellCheckLanguages, Width
Markdown.	FontSize, LineHeight, BlockSpacing, MathFontSize, RenderMath
Appearance.	Theme
Mindmap.	GridType, GridSize, MinimapVisibility
AI.	EnableAssistant, EnableRAG, GpuAcceleration, UnloadTimeout, SmartUnitGeneration
Chat.	StreamingReveal, WipeInputForDictation
Developer.	ChatDatasetLogging, teacher model keys

The settings UI

SettingsViewModel (Mnemo.UI/Modules/Settings/) builds the categories shown to users: Account, General, Editor, AI Tools, Appearance, Mindmap, Updates, Hotkeys, and a gated Developer category. Each row is a small view model (ToggleSettingViewModel, ActionSettingViewModel, dropdowns) bound to a key. The Developer category unlocks after tapping the settings title seven times, which sets a gate key.

A subset of settings is exposed to the AI assistant through SettingsToolService, which keeps an explicit allowlist so the model cannot write arbitrary keys.

Known loose ends

These exist in the UI but are not wired up; do not document them as features and prefer fixing over working around:

• Editor.AutoSave is read by nothing; autosave always runs.
• The Clear cache action has no command handler.
• The Hotkeys category contains a placeholder “New note” rebind row.
• SettingsMnemoPayloadHandler exports legacy Theme.Current/Theme.Mode keys while the runtime uses Appearance.Theme.

Where the code lives

Concern	Path
Service	Mnemo.Infrastructure/Services/SettingsService.cs
Settings UI	Mnemo.UI/Modules/Settings/
AI allowlist	Mnemo.Infrastructure/Services/Tools/SettingsToolService.cs
Package export	Mnemo.Infrastructure/Services/Packaging/PayloadHandlers/ (settings handler)