Module platform 

The parts that differ by platform, behind one small trait. Concept 12 structures the differences as a trait with three implementations rather than treating cross-platform as a yes-or-no decision. This is the launch half of it; the policy sources and the presentation join it in PLAN.md Phases 3 and 4.

Launching does not wait, and cannot. Concept 6 starts from the observation that handing a document to the desktop frequently returns at once, because the file goes to an already-running instance of the target application and there is no child process to wait on. Roughly half of real applications behave that way, so a launch that waited would be right about half the time and silently wrong about the rest. The session model exists because of this, and the launcher’s job stops at handing the file over.

Structs

Host

This machine.

Traits

Launcher

Handing a content file to whatever the desktop says opens it.