feat: add optional scrollbar to the session chat (#5116)

Co-authored-by: Sebastian <[email protected]>
Co-authored-by: opencode-agent[bot] <opencode-agent[bot]@users.noreply.github.com>
Co-authored-by: rekram1-node <[email protected]>

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

@@ -120,6 +120,7 @@ export function Session() {
   const [showTimestamps, setShowTimestamps] = createSignal(kv.get("timestamps", "hide") === "show")
   const [usernameVisible, setUsernameVisible] = createSignal(kv.get("username_visible", true))
   const [showDetails, setShowDetails] = createSignal(kv.get("tool_details_visibility", true))
+  const [showScrollbar, setShowScrollbar] = createSignal(kv.get("scrollbar_visible", false))
   const [diffWrapMode, setDiffWrapMode] = createSignal<"word" | "none">("word")
 
   const wide = createMemo(() => dimensions().width > 120)
@@ -494,6 +495,20 @@ export function Session() {
         dialog.clear()
       },
     },
+    {
+      title: "Toggle session scrollbar",
+      value: "session.toggle.scrollbar",
+      keybind: "scrollbar_toggle",
+      category: "Session",
+      onSelect: (dialog) => {
+        setShowScrollbar((prev) => {
+          const next = !prev
+          kv.set("scrollbar_visible", next)
+          return next
+        })
+        dialog.clear()
+      },
+    },
     {
       title: "Page up",
       value: "session.page.up",
@@ -840,9 +855,9 @@ export function Session() {
             </Show>
             <scrollbox
               ref={(r) => (scroll = r)}
-              scrollbarOptions={{
-                paddingLeft: 2,
-                visible: false,
+              verticalScrollbarOptions={{
+                paddingLeft: 1,
+                visible: showScrollbar(),
                 trackOptions: {
                   backgroundColor: theme.backgroundElement,
                   foregroundColor: theme.border,

packages/opencode/src/config/config.ts

@@ -404,6 +404,7 @@ export namespace Config {
       editor_open: z.string().optional().default("<leader>e").describe("Open external editor"),
       theme_list: z.string().optional().default("<leader>t").describe("List available themes"),
       sidebar_toggle: z.string().optional().default("<leader>b").describe("Toggle sidebar"),
+      scrollbar_toggle: z.string().optional().default("none").describe("Toggle session scrollbar"),
       username_toggle: z.string().optional().default("none").describe("Toggle username visibility"),
       status_view: z.string().optional().default("<leader>s").describe("View status"),
       session_export: z.string().optional().default("<leader>x").describe("Export session to editor"),