Add NPC interaction normalization

internal/modules/dnd/register/merge.go

@@ -57,6 +57,27 @@ func appendCombatTurnLists(values []dnd.CombatTurnList) (dnd.CombatTurnList, err
 	return combined, nil
 }
 
+func appendNPCInteractionLists(values []dnd.NPCInteractionList) (dnd.NPCInteractionList, error) {
+	count := 0
+	present := false
+	for _, value := range values {
+		if value.Interactions != nil {
+			present = true
+		}
+		count += len(value.Interactions)
+	}
+	if !present {
+		return dnd.NPCInteractionList{}, nil
+	}
+	combined := dnd.NPCInteractionList{Interactions: make([]dnd.NPCInteraction, 0, count)}
+	for _, value := range values {
+		for _, interaction := range value.Interactions {
+			combined.Interactions = append(combined.Interactions, cloneNPCInteraction(interaction))
+		}
+	}
+	return combined, nil
+}
+
 func cloneCombatTurn(value dnd.CombatTurn) dnd.CombatTurn {
 	clone := value
 	if value.SourceRefs != nil {
@@ -64,3 +85,11 @@ func cloneCombatTurn(value dnd.CombatTurn) dnd.CombatTurn {
 	}
 	return clone
 }
+
+func cloneNPCInteraction(value dnd.NPCInteraction) dnd.NPCInteraction {
+	clone := value
+	if value.SourceRefs != nil {
+		clone.SourceRefs = append([]source.SourceRef(nil), value.SourceRefs...)
+	}
+	return clone
+}

internal/modules/dnd/register/register_test.go

@@ -185,6 +185,33 @@ func TestAppendNPCListsPreservesOrderAndArrayPresence(t *testing.T) {
 	}
 }
 
+func TestAppendNPCInteractionListsPreservesOrderPresenceAndOwnership(t *testing.T) {
+	refs := []source.SourceRef{{SourceID: "session", StartUnitID: 10, EndUnitID: 10}}
+	input := []dnd.NPCInteractionList{
+		{},
+		{Interactions: []dnd.NPCInteraction{}},
+		{Interactions: []dnd.NPCInteraction{{Name: "Aria", Kind: dnd.NPCInteractionKindDialogue, SourceRefs: refs}}},
+		{Interactions: []dnd.NPCInteraction{{Name: "Borin", Kind: dnd.NPCInteractionKindMentioned, SourceRefs: []source.SourceRef{{SourceID: "session", StartUnitID: 20, EndUnitID: 20}}}}},
+	}
+	got, err := appendNPCInteractionLists(input)
+	if err != nil {
+		t.Fatalf("appendNPCInteractionLists() error = %v", err)
+	}
+	if got.Interactions == nil || !reflect.DeepEqual([]string{got.Interactions[0].Name, got.Interactions[1].Name}, []string{"Aria", "Borin"}) {
+		t.Fatalf("combined interactions = %#v", got)
+	}
+	got.Interactions[0].SourceRefs[0].StartUnitID = 999
+	if input[2].Interactions[0].SourceRefs[0].StartUnitID == 999 {
+		t.Fatal("merged interactions share source reference storage")
+	}
+	for _, values := range [][]dnd.NPCInteractionList{nil, []dnd.NPCInteractionList{{}, {}}} {
+		result, err := appendNPCInteractionLists(values)
+		if err != nil || result.Interactions != nil {
+			t.Fatalf("nil-only merge = %#v, %v; want nil interactions", result, err)
+		}
+	}
+}
+
 func TestAppendCombatTurnListsPreservesOrderPresenceAndOwnership(t *testing.T) {
 	refs := []source.SourceRef{{SourceID: "session", StartUnitID: 1, EndUnitID: 1}}
 	input := []dnd.CombatTurnList{