fix(tui): rendering quality — truncate tool output, wrap code blocks, handle empty responses

4 real bugs in existing rendering code:
1. renderToolOutput: no line limit → truncate to 50 lines + indicator
2. renderCodeBlock: no line wrapping → MaxWidth wrap + 200-line limit
3. renderAssistantBubble: empty response → Thinking… or header-only
4. renderToolCard: input truncation by byte len → display width

Build ✅ | Tests ✅

Author: SIN CI

cmd/sin-code/tui/syntax_highlight.go

@@ -313,6 +313,18 @@ func renderCodeBlock(code, language string, h *SyntaxHighlighter, styles Styles,
 	highlightLines := strings.Split(highlighted, "\n")
 	codeLines := strings.Split(code, "\n")
 
+	const maxCodeLines = 200
+	truncated := false
+	totalLines := len(codeLines)
+	if len(highlightLines) > maxCodeLines {
+		highlightLines = highlightLines[:maxCodeLines]
+		truncated = true
+	}
+	if len(codeLines) > maxCodeLines {
+		codeLines = codeLines[:maxCodeLines]
+		truncated = true
+	}
+
 	var bodyLines []string
 	maxLines := len(highlightLines)
 	if len(codeLines) > maxLines {
@@ -324,6 +336,7 @@ func renderCodeBlock(code, language string, h *SyntaxHighlighter, styles Styles,
 		if i < len(highlightLines) {
 			hl = highlightLines[i]
 		}
+		hl = wrapLine(hl, innerWidth)
 		if showLineNumbers {
 			num = styles.Muted.Render(fmt.Sprintf("%3d ", i+1))
 		} else {
@@ -333,6 +346,10 @@ func renderCodeBlock(code, language string, h *SyntaxHighlighter, styles Styles,
 	}
 	body := strings.Join(bodyLines, "\n")
 
+	if truncated {
+		body += "\n" + styles.Muted.Render(fmt.Sprintf("⋯ %d more lines truncated", totalLines-maxCodeLines))
+	}
+
 	langLabel := ""
 	if language != "" {
 		langLabel = strings.ToLower(strings.TrimSpace(language))
@@ -354,3 +371,13 @@ func renderCodeBlock(code, language string, h *SyntaxHighlighter, styles Styles,
 
 	return hdr.String() + "\n" + body + "\n" + ftr
 }
+
+func wrapLine(line string, maxDisplayWidth int) string {
+	if maxDisplayWidth < 10 {
+		return line
+	}
+	if lipgloss.Width(line) <= maxDisplayWidth {
+		return line
+	}
+	return lipgloss.NewStyle().MaxWidth(maxDisplayWidth).Render(line)
+}

cmd/sin-code/tui/update.go

@@ -2326,6 +2326,13 @@ func renderToolOutput(output string, styles Styles, width int) string {
 		width = 10
 	}
 
+	lines := strings.Split(output, "\n")
+	const maxLines = 50
+	if len(lines) > maxLines {
+		output = strings.Join(lines[:maxLines], "\n")
+		output += fmt.Sprintf("\n⋯ %d more lines (use /tools to see full output)", len(lines)-maxLines)
+	}
+
 	highlighter := NewSyntaxHighlighter(styles.Theme)
 
 	if looksLikeGoCode(output) {
@@ -2638,6 +2645,14 @@ func renderAssistantBubble(msg ChatMessage, highlighter *SyntaxHighlighter, styl
 
 	rendered := renderMarkdownWithCodeBlocks(msg.Text, highlighter, styles, bodyWidth)
 
+	if strings.TrimSpace(rendered) == "" {
+		if streaming {
+			rendered = styles.Muted.Render("Thinking…")
+		} else {
+			return headerLine + "\n"
+		}
+	}
+
 	if streaming {
 		cursor := renderStreamingCursor(spinner, styles)
 		rendered = strings.TrimRight(rendered, "\n") + cursor
@@ -2725,7 +2740,7 @@ func renderToolCard(msg ChatMessage, styles Styles, width int, focused bool) str
 
 		if msg.ToolInput != "" {
 			inputText := msg.ToolInput
-			if len(inputText) > bodyWidth-10 {
+			if lipgloss.Width(inputText) > bodyWidth-10 {
 				inputText = truncateString(inputText, bodyWidth-13)
 			}
 			b.WriteString(styles.Muted.Render("  in: "))