Peek preview
View issue details without having to open issues.

Overview
Peek is one the semi-secrets of the Linear UI. It lets you view details of focused issues at a glance from any list or board view, similar to Quicklook in macOS.
Tap Space to toggle peek on or off
Space and hold to turn on peek only while Space is depressed
Configure
Peek is a default setting in Linear available on many issue views, the Inbox, and project lists. If peek is available for your page or view, you can launch it by pressing the Space bar and turn it off by pressing the Space bar again. To temporarily turn it on, hold the Space bar down. Peek will remain active until you let go of the Space bar.
Basics
Issue lists
Press Space to launch peek, then scroll through a list or board with (J/K or ↑/↓) to launch the issue peep pop up. It'll show a preview issue details including the description, assignee, status, priority, cycle, labels, estimate, creation date, and updated date.
Projects
Peek also works for projects in the projects view or roadmap. Use the same shortcut Space to launch issue peek, then scroll with the up / down arrows or use your mouse to hover over a project name in the list or project bar. Peek will show project details as well as the project graph.
Inbox and Triage
Peek will work to launch an issue preview on Triage and Inbox views so that you don't have to open the issue to remember what it's about.