Plan shell completion implementation

docs/roadmap/deferred.md

@@ -25,12 +25,28 @@ unselected extensions to the delivered ConfigKit comparison. Consider them only
 for a concrete consumer need and a deliberate API/behavior decision under the
 relevant ADRs.
 
+### Alias completion and discovery
+
+The [shell-completion roadmap](completion.md) selects an initial MVP with
+canonical suggestions and alias-aware interpretation. Potential future work
+includes suggesting command and flag alias spellings and valid continuations of
+alias-only prefixes. For example, completion could suggest `inspect` after
+`app legacy ` when `legacy inspect` is an installed alias.
+
+Alias discovery may be omitted from the MVP. This deferral does not establish a
+permanent canonical-only completion contract or prohibit future alias discovery.
+A later design should determine how alias suggestions are presented alongside
+canonical suggestions while ensuring inserted continuations form valid next
+steps. No delivery date or final API is selected here.
+
 ## Other deferred proposals
 
 These capabilities remain outside the delivered scope and require a concrete
 operator or consumer need and an appropriate ownership/behavior decision:
 
-- JSON reports, shell completion, and output-file management or reloadable export.
+- JSON reports and output-file management or reloadable export.
+- Shell-completion extensions beyond the initial scope in the
+  [completion roadmap](completion.md), including alias discovery described above.
 - Configuration mutation, generic value assignment, and exhaustive field-origin
   inventories.
 - Credential diagnostics beyond PromptKit's native smoke checks and additional