Rough-in support for deepseeek-style separate reasoning output

pkg/tui/views/chat/update.go

@@ -33,6 +33,14 @@ func (m *Model) setMessageContents(i int, content string) {
 	m.messageCache[i] = m.renderMessage(i)
 }
 
+func (m *Model) setReasoningContents(i int, content string) {
+	if i >= len(m.App.Messages) {
+		panic("i out of range")
+	}
+	m.App.Messages[i].ReasoningContent = content
+	m.messageCache[i] = m.renderMessage(i)
+}
+
 func (m *Model) rebuildMessageCache() {
 	m.messageCache = make([]string, len(m.App.Messages))
 	for i := range m.App.Messages {
@@ -108,7 +116,7 @@ func (m *Model) Update(msg tea.Msg) (shared.ViewModel, tea.Cmd) {
 	case msgChatResponseChunk:
 		cmds = append(cmds, m.waitForResponseChunk()) // wait for the next chunk
 
-		if msg.Content == "" {
+		if msg.Content == "" && msg.ReasoningContent == "" {
 			// skip empty chunks
 			break
 		}
@@ -116,19 +124,27 @@ func (m *Model) Update(msg tea.Msg) (shared.ViewModel, tea.Cmd) {
 		last := len(m.App.Messages) - 1
 		if last >= 0 && m.App.Messages[last].Role.IsAssistant() {
 			// append chunk to existing message
-			m.setMessageContents(last, m.App.Messages[last].Content+msg.Content)
+			if msg.Content != "" {
+				m.setMessageContents(last, m.App.Messages[last].Content+msg.Content)
+			}
+			if msg.ReasoningContent != "" {
+				m.setReasoningContents(last, m.App.Messages[last].ReasoningContent+msg.ReasoningContent)
+			}
 		} else {
 			// use chunk in a new message
 			m.addMessage(conversation.Message{
 				Role:    api.MessageRoleAssistant,
 				Content: msg.Content,
+				ReasoningContent: msg.ReasoningContent,
 			})
 		}
 		m.updateContent()
 
 		// show cursor and reset blink interval (simulate typing)
-		m.replyCursor.Blink = false
-		cmds = append(cmds, m.replyCursor.BlinkCmd())
+		if msg.ReasoningContent == "" || m.showDetails {
+			m.replyCursor.Blink = false
+			cmds = append(cmds, m.replyCursor.BlinkCmd())
+		}
 
 		m.tokenCount += msg.TokenCount
 		m.elapsed = time.Now().Sub(m.startTime)
@@ -137,6 +153,7 @@ func (m *Model) Update(msg tea.Msg) (shared.ViewModel, tea.Cmd) {
 
 		reply := conversation.Message(msg)
 		reply.Content = strings.TrimSpace(reply.Content)
+		reply.ReasoningContent = strings.TrimSpace(reply.ReasoningContent)
 
 		last := len(m.App.Messages) - 1
 		if last < 0 {

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())
 	}