Validate command alias termination

docs/roadmap/implementation.md

@@ -321,6 +321,14 @@ finite cases. Verified with `go test ./internal/alias`.
 cases distinguish it from conservative declaration-cycle or bounded simulation
 checks. Do not integrate an approximate validator and defer correctness.
 
+**Completed:** Added worklist saturation for finite pop summaries, head-graph
+construction, cycle detection, and errors naming participating mappings.
+Terminal-marker transitions preserve the unique bottom marker, and tests verify
+markers cannot be popped. Direct, growing, and suffix-dependent loops are
+rejected; consuming repetition, longest-match suppression, and 80-rule chains
+in either registration order are accepted. Verified with
+`go test ./internal/alias -count=1`.
+
 ## Stage 4: Add captured declaration types and factories
 
 **Work**