docs: define ASAPPlanner input, output, and workflow

docs/design_docs/README.md

@@ -7,6 +7,9 @@ decisions, and evolving proposals.
   and Pre-ASAP/Post-ASAP representations.
 - [Architecture](architecture/README.md) describes stable component boundaries
   and system flows.
+- [Planner input, output, and workflow](architecture/input-output-workflow.md)
+  defines the user-facing contract, required and optional inputs, output data
+  structures, and initial-planning and replanning workflows.
 - [Decisions](decisions/README.md) records accepted local design choices.
 - [Proposals](proposals/README.md) contains evolving designs and research
   directions; check each document’s status before treating it as current.

docs/design_docs/architecture/README.md

@@ -6,6 +6,10 @@ It does not commit, deploy, or execute a physical plan; downstream systems such
 as ASAPQuery-backend bind the candidates to physical alternatives, make the
 deployment-level decision, and run the selected contract.
 
+For the integration contract, start with [ASAPPlanner input, output, and
+workflow](input-output-workflow.md). It defines required and optional inputs,
+`PlanSpace` and selected-plan outputs, lifecycle requirements, and replanning.
+
 ## Planner component flow
 
 ```mermaid