Function session 

pub fn session(workspace: &str) -> Option<ContentStore>

The content workspace holds, read through the document media the session this process runs in serves its apps (TILO_FS_BLOB_SOCKET, fs serve-media), or None when none is served.

A session’s own process draws the same pictures its apps do — the shell composes views of records whose stills an app’s connector kept — and the launcher handed it no capability of its own, so this is where it reads them from. Which workspace a picture is in is the caller’s to say: the session serves a place’s pictures from the workspace that place stands in.