Load ordinary overlays without a main source

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Configuration Discovery Implementation Plan
 
-Status: in progress. Stages 1, 2, 3, and 4 are complete.
+Status: in progress. Stages 1, 2, 3, 4, and 5 are complete.
 
 Implement the target behavior in [the discovery roadmap](discovery.md). That
 document owns the selected conventions and OD-1 through OD-5; this plan owns the
@@ -297,7 +297,7 @@ Acceptance: imports can be enabled on absent input without synthetic sources,
 while invalid supplied contexts still fail. Run focused load, filesystem,
 version, and grouped tests, then the everyday check; mark and commit.
 
-## Stage 5 — Load Ordinary Overlays With An Absent Main
+## Stage 5 — Load Ordinary Overlays With An Absent Main (Complete)
 
 1. Replace the ordinary `NoSource` active-overlay rejection with the explicit
    context requirement. Resolve absent-input overlay access from its context;