Rough-in support for deepseeek-style separate reasoning output

pkg/tui/views/chat/view.go

@@ -116,19 +116,42 @@ func (m *Model) renderMessage(i int) string {
 
 	// Write message contents
 	sb := &strings.Builder{}
-	sb.Grow(len(msg.Content) * 2)
+	sb.Grow((len(msg.Content) + len(msg.ReasoningContent) * 2))
+
+	isLast := i == len(m.App.Messages)-1
+	isAssistant := msg.Role == api.MessageRoleAssistant
+	hasReasoning := msg.ReasoningContent != ""
+
+	if hasReasoning {
+		reasoning := strings.Builder{}
+		reasoning.WriteString("<thinking>\n")
+		if m.showDetails {
+			//_ = m.App.Ctx.Chroma.Highlight(sb, msg.ReasoningContent)
+			reasoning.WriteString(msg.ReasoningContent)
+		} else {
+			reasoning.WriteString("...")
+		}
+		if m.state == pendingResponse && isLast && isAssistant && msg.Content == "" {
+			// Show the assistant's cursor
+			reasoning.WriteString(m.replyCursor.View())
+		}
+		reasoning.WriteString("\n</thinking>")
+		_ = m.App.Ctx.Chroma.Highlight(sb, reasoning.String())
+	}
+
 	if msg.Content != "" {
+		if hasReasoning {
+			sb.WriteString("\n\n")
+		}
 		err := m.App.Ctx.Chroma.Highlight(sb, msg.Content)
 		if err != nil {
+			// This would wipe out the thinking text
 			sb.Reset()
 			sb.WriteString(msg.Content)
 		}
 	}
 
-	isLast := i == len(m.App.Messages)-1
-	isAssistant := msg.Role == api.MessageRoleAssistant
-
-	if m.state == pendingResponse && isLast && isAssistant {
+	if m.state == pendingResponse && isLast && isAssistant && (!hasReasoning || msg.Content != "") {
 		// Show the assistant's cursor
 		sb.WriteString(m.replyCursor.View())
 	}