Consolidate D&D entity documentation

docs/integrations/dnd-item-occurrence-artifacts.md

@@ -14,9 +14,11 @@ inventory, balance, or ledger.
 | Schema version | `v1` |
 | Media type | `application/json` |
 
-The strict root has required `occurrences`. Records require `item_id`, `name`,
-`kind`, and `source_refs`; unknown fields are rejected. `quantity`, `from`, and
-`to` appear only when their kind permits them.
+`v1` accepts one strict JSON object with required `occurrences`; the array may
+be empty. Each occurrence has required `item_id`, `name`, `kind`, and
+`source_refs`, and occurrence and source-reference objects reject unknown
+fields. `quantity`, `from`, and `to` appear only when their kind permits them.
+An incompatible shape change requires a new schema version.
 
 ## Registry grounding
 
@@ -33,6 +35,10 @@ pairs.
 
 ## Wire shape
 
+Each source reference has exactly `source_id`, `start_unit_id`, and
+`end_unit_id`. It identifies an inclusive range in the current transcript;
+unit IDs are positive and the start may not follow the end.
+
 ```json
 {
   "occurrences": [
@@ -54,7 +60,10 @@ The five kinds remain `discovered`, `acquired`, `lost`, `consumed`, and
 `transferred`. Holder, quantity, currency, ordering, and exact-duplicate rules
 are unchanged: discovered has no holder; acquired requires `to`; lost and
 consumed require `from`; transferred requires distinct non-`party` holders.
-Each source reference is an inclusive current-transcript range.
+The only current downstream compatibility requirement is its registry handoff;
+the normalized occurrence list is otherwise published for callers. See
+[Configuration](../config.md#d-d-reference-slots) for the binding and
+[JSON output](json-output.md) for publication.
 
 See [item registry](dnd-item-registry-artifacts.md) for the grounding artifact
 and [D&D module internals](../internal/dnd.md) for implementation details.