diff --git a/ui-tui-opentui-v2/src/view/messageLine.tsx b/ui-tui-opentui-v2/src/view/messageLine.tsx
index 0fa345506e8..612f2b92706 100644
--- a/ui-tui-opentui-v2/src/view/messageLine.tsx
+++ b/ui-tui-opentui-v2/src/view/messageLine.tsx
@@ -56,7 +56,10 @@ export function MessageLine(props: { message: Message }) {
             <Show
               when={m().streaming && !hasParts()}
               fallback={
-                <text>
+                // themed selection: a solid muted/accent bar that preserves the
+                // text fg (no selectionFg → the original color shows through, so a
+                // highlight over content reads as a clean bar, not SGR-inverse).
+                <text selectionBg={theme().color.selectionBg}>
                   <span style={{ fg: bodyFg() }}>{m().text}</span>
                 </text>
               }
diff --git a/ui-tui-opentui-v2/src/view/toolPart.tsx b/ui-tui-opentui-v2/src/view/toolPart.tsx
index 6f44d1b25b3..5dc1a4c4d6f 100644
--- a/ui-tui-opentui-v2/src/view/toolPart.tsx
+++ b/ui-tui-opentui-v2/src/view/toolPart.tsx
@@ -148,7 +148,7 @@ export function ToolPart(props: { part: ToolPartState }) {
                 fallback={
                   <For each={(props.part.argsText ?? '').split('\n').slice(0, ARGS_MAX)}>
                     {line => (
-                      <text>
+                      <text selectionBg={theme().color.selectionBg}>
                         <span style={{ fg: theme().color.muted }}>{truncate(line, bodyWidth() - 2)}</span>
                       </text>
                     )}
@@ -157,7 +157,7 @@ export function ToolPart(props: { part: ToolPartState }) {
               >
                 <For each={argEntries().slice(0, ARGS_MAX)}>
                   {([k, v]) => (
-                    <text>
+                    <text selectionBg={theme().color.selectionBg}>
                       <span style={{ fg: theme().color.muted }}>{truncate(argLine(k, v), bodyWidth() - 2)}</span>
                     </text>
                   )}
@@ -176,9 +176,11 @@ export function ToolPart(props: { part: ToolPartState }) {
                 <span style={{ fg: theme().color.label }}>output</span>
               </text>
             </Show>
+            {/* output body lines are the copyable content → themed selection bar
+                (preserves fg; same token as message text) (item: theme highlight). */}
             <For each={body().lines}>
               {line => (
-                <text>
+                <text selectionBg={theme().color.selectionBg}>
                   <span style={{ fg: theme().color.muted }}>{line}</span>
                 </text>
               )}