Class PlainRenderer

src/main/java/com/tcode/render/PlainRenderer.java:26–305

Plain 渲染器：纯 println 模式，等价 phase-15 行为，无折叠、无状态栏。 同时充当 inline / lanterna 两套实现的回退基线——任何高级特性都退化成普通文本。

 * <p>同时充当 inline / lanterna 两套实现的回退基线——任何高级特性都退化成普通文本。
 */
public final class PlainRenderer implements Renderer {

    private static final ObjectMapper JSON = new ObjectMapper();

    private final PrintStream out;
    private final BufferedReader in;

    public PlainRenderer() {
        this(System.out, new BufferedReader(new InputStreamReader(System.in, StandardCharsets.UTF_8)));
    }

    PlainRenderer(PrintStream out, BufferedReader in) {
        this.out = out;
        this.in = in;
    }

    @Override
    public void start() {
        // no-op
    }

    @Override
    public void close() {
        // no-op：不接管 System.out / System.in，启动者自己管生命周期
    }

    @Override
    public PrintStream stream() {
        return out;
    }

    @Override
    public void appendToolCalls(List<LlmClient.ToolCall> toolCalls) {
        if (toolCalls == null || toolCalls.isEmpty()) {
            return;
        }
        Map<String, List<LlmClient.ToolCall>> grouped = new LinkedHashMap<>();
        for (LlmClient.ToolCall tc : toolCalls) {
            grouped.computeIfAbsent(tc.function().name(), k -> new ArrayList<>()).add(tc);
        }
        for (var group : grouped.entrySet()) {
            String toolName = group.getKey();
            List<LlmClient.ToolCall> calls = group.getValue();
            out.println(AnsiStyle.subtle("  " + toolLabel(toolName, calls.size())));
            for (LlmClient.ToolCall tc : calls) {
                String detail = extractKeyParam(toolName, tc.function().arguments());
                if (!detail.isEmpty()) {
                    out.println(AnsiStyle.subtle("    └ " + detail));
                }
            }
        }
    }

    @Override
    public void appendDiff(String filePath, String before, String after) {
        out.println();
        out.println(AnsiStyle.heading("📝 " + (filePath == null ? "(unnamed)" : filePath)));
        if (before == null && after != null) {