Revise the Seriatim plan and workspace conventions

docs/roadmap/features/template.md

@@ -34,6 +34,14 @@ application contracts.
 Link the MVP roadmap and applicable decision records. Record technical or
 operational constraints that implementations must preserve.
 
+## Simplest Viable Implementation
+
+Outline the direct, module-driven task flow at the level needed to constrain
+the implementation without turning the roadmap into an execution plan. Trust
+module idempotence and change detection. Identify any non-obvious probe,
+sidecar state, staging mechanism, command, or abstraction and tie it to a
+specific acceptance criterion.
+
 ## Rationale and Alternatives
 
 Explain material tradeoffs and why the selected end state is preferred. Omit
@@ -47,3 +55,8 @@ this section when the choice is mechanical and needs no durable rationale.
 
 List prerequisites and explicitly deferred work without expanding this
 feature's scope.
+
+## Potential Future Hardening
+
+List worthwhile security or resilience improvements that are deliberately not
+part of the initial implementation. Omit this section when there are none.