Parse shared debug input once

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Shared debug binding implementation plan
 
-Status: in progress; Stages 1–2 complete.
+Status: in progress; Stages 1–3 complete.
 Baseline: `6727d22ce6e1ac668b56a3e6d8fa5f7a06e54d88`.
 Execution audience: Luna coding agent.
 
@@ -146,6 +146,11 @@ Backend-dependent checks may remain pending until Stage 3.
 
 ## Stage 3 — Parse one debug option into both consumers
 
+**Complete.** Backend registration and interpretation use effective flags while
+consumer values retain their original indexes. Public mode/value cases, aliases,
+invalid values, option-looking values and terminated operands pass, as do focused
+backend parsing checks, offline with Go 1.27.0.
+
 Primary files: [backend parse.go](../../internal/cobra/parse.go),
 [backend flags.go](../../internal/cobra/flags.go),
 [parser.go](../../parser.go), [binding.go](../../binding.go).