Double that. Sessions currently require way to many clicks if they are to be used as "temporary workspace I use sometimes". A few comments, however:
"Save an open workspace as a session" should be phrased differently to clearly indicate that workspace would be deleted and saved as a session. Something along the lines "Archive as Session".
When workspace is archived - it should indicate that session is a workspace archive, as well as retain the workspace icon.
Double-clicking such session would restore the workspace. Context menu should have both "Open in current window" and "Open in new window", unless workspace already exists and is active, provide simple "Open" in that case.
If there's already a workspace under same name present - it should prompt user to choose between override, append, append new (i.e. avoid duplicate tabs) or cancel. "Append new" would check existing tabs in the workspace and add only ones url of which is not already present.
The following options need to be available for users to customize feature to their liking:
Delete workspace after archiving (Default on) Delete session after restoring (Default off) What to do if workspace already exists (Default Ask, override, append, append new) Where to open the workspace by default: In current window (default) or in new window. When workspace exists and is active in any window - option is ignored and switches to that window instead. This behavior should be explicitly stated. (Nice to have tier) Limit the session history size for archived workspaces.All available in Settings and not as prompt during the action itself. Action itself should require as little clicks as possible.