Harden item occurrence grounding

internal/modules/dnd/items/identity/identity.go

@@ -8,10 +8,8 @@ import (
 	"fmt"
 	"strings"
 
-	"golang.org/x/text/cases"
-	"golang.org/x/text/unicode/norm"
-
 	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd"
+	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/shared"
 )
 
 const (
@@ -51,17 +49,7 @@ func NormalizeDisplay(value string) string {
 
 // ComparisonKey returns the stable key used for item-type identity comparisons.
 func ComparisonKey(value string) string {
-	value = norm.NFKC.String(value)
-	value = strings.Map(func(r rune) rune {
-		switch r {
-		case '\u2018', '\u2019', '\u02bc':
-			return '\''
-		default:
-			return r
-		}
-	}, value)
-	value = strings.Join(strings.Fields(value), " ")
-	return cases.Fold().String(value)
+	return shared.ComparisonKey(value)
 }
 
 // DeriveID returns the deterministic ID for an item type. Empty identity keys

internal/modules/dnd/items/identity/identity_test.go

@@ -9,29 +9,6 @@ import (
 	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd"
 )
 
-func TestComparisonKeyNormalizesSupportedEquivalences(t *testing.T) {
-	tests := []struct {
-		name  string
-		left  string
-		right string
-	}{
-		{name: "case", left: "Silver Key", right: "sILVER kEY"},
-		{name: "compatibility", left: "Ｓｉｌｖｅｒ Ｋｅｙ", right: "Silver Key"},
-		{name: "whitespace", left: "  Silver\u2003Key ", right: "Silver Key"},
-		{name: "apostrophe", left: "Healer’s Kit", right: "healer's kit"},
-	}
-	for _, test := range tests {
-		t.Run(test.name, func(t *testing.T) {
-			if ComparisonKey(test.left) != ComparisonKey(test.right) {
-				t.Fatalf("ComparisonKey(%q) = %q, ComparisonKey(%q) = %q", test.left, ComparisonKey(test.left), test.right, ComparisonKey(test.right))
-			}
-		})
-	}
-	if ComparisonKey("Silver Key") == ComparisonKey("Gold Key") {
-		t.Fatal("different item types received the same comparison key")
-	}
-}
-
 func TestDeriveIDUsesExactCompactIdentityBytes(t *testing.T) {
 	const wantID = "item:sha256:2f211c60b9bdcf3a6dd64086cc4c05df5b3357ae02cb462f7ef8988d9bd2fa4f"
 	const wantIdentity = `["dnd.item_registry.identity.v1","silver key"]`