some comments never hurt

ui2/src/components/DualPanel/DualPanel.tsx

@@ -22,7 +22,7 @@ export default function DualPanel() {
   }
 
   return (
-    <PanelContext.Provider value="main">
+    <PanelContext.Provider value={"main"}>
       <SinglePanel />
     </PanelContext.Provider>
   )

ui2/src/contexts/PanelContext.ts

@@ -1,6 +1,17 @@
 import {createContext} from "react"
 import type {PanelMode} from "@/types"
 
+/*
+`@/component/DualPanel` component features two panels. One of the panels
+is called "main" and another one "secondary". Both panels
+are rendered using same `@/components/SinglePanel` component. In
+order to distinguish between the two - panel mode is passed as via
+react context.
+Panel with mode "main" (i.e. main panel) is always present.
+Panel with mode "secondary" - may or may not be present; in other
+words, "secondary" panel may be closed, while "main" panel
+cannot be closed.
+*/
 const PanelContext = createContext<PanelMode>("main")
 
 export default PanelContext