unified-storage: use name instead of offset in kvstore continue token (#113560)

* unified-storage: use name instead of offset in kvstore continue token

---------

Co-authored-by: Georges Chaudy <chaudyg@gmail.com>

pkg/storage/unified/resource/continue_test.go

@@ -4,13 +4,54 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestContinueToken(t *testing.T) {
-	token := &ContinueToken{
-		ResourceVersion: 100,
-		StartOffset:     50,
-		SortAscending:   false,
-	}
-	assert.Equal(t, "eyJvIjo1MCwidiI6MTAwLCJzIjpmYWxzZX0=", token.String())
+	t.Run("round-trip with namespace (cross-namespace query)", func(t *testing.T) {
+		original := ContinueToken{
+			Namespace:       "my-namespace",
+			Name:            "my-resource",
+			ResourceVersion: 200,
+		}
+		decoded, err := GetContinueToken(original.String())
+		require.NoError(t, err)
+		assert.Equal(t, original.Namespace, decoded.Namespace)
+		assert.Equal(t, original.Name, decoded.Name)
+		assert.Equal(t, original.ResourceVersion, decoded.ResourceVersion)
+	})
+
+	t.Run("round-trip without namespace (single-namespace query)", func(t *testing.T) {
+		original := ContinueToken{
+			Name:            "test-resource",
+			ResourceVersion: 100,
+		}
+		decoded, err := GetContinueToken(original.String())
+		require.NoError(t, err)
+		assert.Equal(t, "", decoded.Namespace)
+		assert.Equal(t, original.Name, decoded.Name)
+		assert.Equal(t, original.ResourceVersion, decoded.ResourceVersion)
+	})
+
+	t.Run("history token (no name, uses ResourceVersion for pagination)", func(t *testing.T) {
+		original := ContinueToken{
+			ResourceVersion: 500,
+			SortAscending:   true,
+		}
+		decoded, err := GetContinueToken(original.String())
+		require.NoError(t, err)
+		assert.Equal(t, "", decoded.Name)
+		assert.Equal(t, int64(500), decoded.ResourceVersion)
+		assert.True(t, decoded.SortAscending)
+	})
+
+	t.Run("rejects invalid base64", func(t *testing.T) {
+		_, err := GetContinueToken("not-valid-base64!")
+		assert.Error(t, err)
+	})
+
+	t.Run("rejects invalid json", func(t *testing.T) {
+		_, err := GetContinueToken("bm90LWpzb24=") // "not-json" in base64
+		assert.Error(t, err)
+	})
 }