fix(tui): simplify thinking toggle styling (#28487)

packages/opencode/src/cli/cmd/tui/feature-plugins/system/session-v2.tsx

@@ -411,12 +411,9 @@ function AssistantReasoning(props: {
       <Switch>
         <Match when={!inMinimal() || expanded()}>
           <box
-            paddingLeft={2}
+            paddingLeft={3}
             marginTop={1}
             flexDirection="column"
-            border={["left"]}
-            customBorderChars={SplitBorder.customBorderChars}
-            borderColor={theme.backgroundElement}
             flexShrink={0}
             onMouseUp={toggle}
           >
@@ -425,17 +422,20 @@ function AssistantReasoning(props: {
               drawUnstyledText={false}
               streaming={true}
               syntaxStyle={props.subtleSyntax}
-              content={(inMinimal() ? "▼ " : "") + "_Thinking:_ " + content()}
+              content={(inMinimal() ? "- " : "") + "_Thinking:_ " + content()}
               conceal={true}
               fg={theme.textMuted}
             />
           </box>
         </Match>
         <Match when={isDone()}>
-          <box paddingLeft={3} marginTop={1} flexShrink={0} onMouseUp={toggle}>
-            <text fg={theme.textMuted} wrapMode="none">
-              {title() ? "▶ Thought: " + title() : "▶ Thought"}
-            </text>
+          <box
+            paddingLeft={3}
+            marginTop={1}
+            flexShrink={0}
+            onMouseUp={toggle}
+          >
+            <CollapsedReasoningText title={title()} />
           </box>
         </Match>
         <Match when={true}>
@@ -448,6 +448,16 @@ function AssistantReasoning(props: {
   )
 }
 
+function CollapsedReasoningText(props: { title: string | null }) {
+  const { theme } = useTheme()
+
+  return (
+    <text fg={theme.warning} wrapMode="none">
+      <span style={{ fg: theme.warning, italic: true }}>{props.title ? "+ Thought · " + props.title : "+ Thought"}</span>
+    </text>
+  )
+}
+
 function AssistantTool(props: { part: SessionMessageAssistantTool; sessionID: string }) {
   const input = createMemo(() => toolInputRecord(props.part.state.input))
   const toolprops = {