fix: hide duplicate StreamingIndicator during thinking, fix plain text color in code blocks

- StreamingIndicator now only shows during 'tool_executing' state
  (ThinkingBlock already animates during 'thinking')
- Plain text code blocks force dark color (#24292f) instead of prism's
  default faded gray which was invisible on our beige background

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

desktop/src/components/chat/CodeViewer.tsx

@@ -40,6 +40,7 @@ export function CodeViewer({ code, language, maxLines = 20, showLineNumbers = tr
             <pre className="m-0 bg-white p-0 font-[var(--font-mono)] text-[12px] leading-[1.3]">
               {tokens.map((line, i) => {
                 const lineProps = getLineProps({ line })
+                const hasLanguage = !!language && language !== 'text'
                 return effectiveShowLineNumbers ? (
                   <div
                     key={i}
@@ -63,10 +64,16 @@ export function CodeViewer({ code, language, maxLines = 20, showLineNumbers = tr
                     className="hover:bg-[#f6f8fa]/50"
                     style={undefined}
                   >
-                    <span className="block px-3 py-px whitespace-pre-wrap break-words">
-                      {line.map((token, key) => (
-                        <span key={key} {...getTokenProps({ token })} />
-                      ))}
+                    <span className={`block px-3 py-px whitespace-pre-wrap break-words ${!hasLanguage ? 'text-[#24292f]' : ''}`}>
+                      {hasLanguage ? (
+                        line.map((token, key) => (
+                          <span key={key} {...getTokenProps({ token })} />
+                        ))
+                      ) : (
+                        line.map((token, key) => (
+                          <span key={key} {...getTokenProps({ token })} style={{ color: '#24292f' }} />
+                        ))
+                      )}
                     </span>
                   </div>
                 )

desktop/src/components/chat/MessageList.tsx

@@ -117,7 +117,10 @@ export function MessageList() {
           <AssistantMessage content={streamingText} isStreaming />
         )}
 
-        {chatState !== 'idle' && chatState !== 'streaming' && chatState !== 'permission_pending' && (
+        {/* Only show StreamingIndicator for tool_executing state.
+            During 'thinking', the active ThinkingBlock already shows animation.
+            During 'streaming', the AssistantMessage shows the cursor. */}
+        {chatState === 'tool_executing' && (
           <StreamingIndicator />
         )}