diff --git a/lib/hyper.d.ts b/lib/hyper.d.ts
new file mode 100644
index 00000000..31d332b5
--- /dev/null
+++ b/lib/hyper.d.ts
@@ -0,0 +1,22 @@
+declare global {
+  interface Window {
+    __rpcId: string;
+  }
+}
+
+export type ITermGroup = {
+  uid: string | null;
+  sessionUid: string | null;
+  parentUid: string | null;
+  direction: string | null;
+  sizes: number[] | null;
+  children: string[];
+};
+
+export type ITermGroups = Record<string, ITermGroup>;
+
+export type ITermState = {
+  termGroups: ITermGroups;
+  activeSessions: Record<string, string>;
+  activeRootGroup: string | null;
+};