Store information about recently used kernels or launcher items more generally?

[krassowski]

Problem

The launcher and the kernel selection dialog can be hard to use when multiple kernels are installed. This was previously reported in #3795 for launcher (20 👍 as of the day of writing) but also discussed in extensions such as jupyterlab-conda-store (conda-incubator/conda-store-ui#255).

Proposed Solution

The mockup in #3795 (comment) proposes adding a new section for "Recent" items. Regardless of whether we decide to have this functionality in core, and whether this will be a new section, or an option to change sort order, we would need to store the information about when each kernel/launcher item was most recently used; this may be difficult to achieve in extensions though as kernels can be selected or started in various ways.

Additional context

PR #15483 included in JupyterLab 4.2 introduced a manager for recently opened/closed documents:

jupyterlab/packages/docmanager/src/tokens.ts

Lines 294 to 327 in 2ceabd8

	export interface IRecentsManager extends IDisposable {
	/**
	* Get the recently opened documents.
	*/
	readonly recentlyOpened: RecentDocument[];
	/**
	* Get the recently closed items.
	*/
	readonly recentlyClosed: RecentDocument[];
	/**
	* Signal emitted when either of the list changes.
	*/
	readonly changed: ISignal<IRecentsManager, void>;
	/**
	* Check if the recent item is valid, remove if it from both lists if it is not.
	*/
	validate(recent: RecentDocument): Promise<boolean>;
	/**
	* Add a new path to the recent list.
	*/
	addRecent(
	document: Omit<RecentDocument, 'root'>,
	event: 'opened' | 'closed'
	): void;
	/**
	* Remove the document from recents list.
	*/
	removeRecent(document: RecentDocument, event: 'opened' | 'closed'): void;
	}

We could reuse it to also record info about the launcher items, or we could have a different plugin for this purpose (which might be better from the point of plugin dependency graph).