feat(tui): add header visibility toggle

packages/opencode/src/cli/cmd/tui/app.tsx

@@ -610,6 +610,15 @@ function App() {
         dialog.clear()
       },
     },
+    {
+      title: kv.get("header_visible", true) ? "Hide header" : "Show header",
+      value: "session.toggle.header",
+      category: "System",
+      onSelect: (dialog) => {
+        kv.set("header_visible", !kv.get("header_visible", true))
+        dialog.clear()
+      },
+    },
   ])
 
   createEffect(() => {

packages/opencode/src/cli/cmd/tui/routes/session/index.tsx

@@ -149,6 +149,7 @@ export function Session() {
   const [showDetails, setShowDetails] = kv.signal("tool_details_visibility", true)
   const [showAssistantMetadata, setShowAssistantMetadata] = kv.signal("assistant_metadata_visibility", true)
   const [showScrollbar, setShowScrollbar] = kv.signal("scrollbar_visible", false)
+  const [showHeader] = kv.signal("header_visible", true)
   const [diffWrapMode] = kv.signal<"word" | "none">("diff_wrap_mode", "word")
   const [animationsEnabled, setAnimationsEnabled] = kv.signal("animations_enabled", true)
 
@@ -959,7 +960,9 @@ export function Session() {
         <box flexGrow={1} paddingBottom={1} paddingTop={1} paddingLeft={2} paddingRight={2} gap={1}>
           <Show when={session()}>
             <Show when={!sidebarVisible() || !wide()}>
-              <Header />
+              <Show when={showHeader()}>
+                <Header />
+              </Show>
             </Show>
             <scrollbox
               ref={(r) => (scroll = r)}