diff --git a/crates/focus-tui/src/app.rs b/crates/focus-tui/src/app.rs
index f1132ac..e840432 100644
--- a/crates/focus-tui/src/app.rs
+++ b/crates/focus-tui/src/app.rs
@@ -195,6 +195,9 @@ pub struct App {
     /// 已提交 assistant 消息的思考耗时（(消息索引, 内容索引) → 毫秒）。
     /// Committed assistant thinking durations ((message idx, content idx) → ms).
     pub thinking_durations: HashMap<(usize, usize), u64>,
+    /// 已提交 tool_result 消息的执行耗时（(消息索引, 0) → 毫秒）。
+    /// Committed tool_result execution durations ((message idx, 0) → ms).
+    pub tool_durations: HashMap<(usize, usize), u64>,
     pub expanded: HashSet<BlockId>,
     pub notes: Vec<String>,
     pub status: String,
@@ -232,6 +235,7 @@ impl App {
             run_join: None,
             run_state: None,
             thinking_durations: HashMap::new(),
+            tool_durations: HashMap::new(),
             expanded: HashSet::new(),
             notes: Vec::new(),
             status: String::new(),
@@ -422,16 +426,33 @@ impl App {
                     let tail_start = messages.len().saturating_sub(appended_count);
                     let mut turn = 0usize;
                     for (off, msg) in messages.iter().enumerate().skip(tail_start) {
-                        if let Message::Assistant(a) = msg {
-                            for (bi, block) in a.content.iter().enumerate() {
-                                if let ContentBlock::Thinking(_) = block {
-                                    if let Some(timing) = rs.thinking.get(&(turn, bi)) {
-                                        self.thinking_durations
-                                            .insert((off, bi), timing.duration_ms());
+                        match msg {
+                            Message::Assistant(a) => {
+                                for (bi, block) in a.content.iter().enumerate() {
+                                    if let ContentBlock::Thinking(_) = block {
+                                        if let Some(timing) = rs.thinking.get(&(turn, bi)) {
+                                            self.thinking_durations
+                                                .insert((off, bi), timing.duration_ms());
+                                        }
+                                    }
+                                }
+                                turn += 1;
+                            }
+                            Message::ToolResult(t) => {
+                                // 把该轮的工具执行耗时映射到 tool_result 消息。
+                                // Map the tool-execution duration onto the
+                                // tool_result message.
+                                if let Some(exec) = rs
+                                    .tool_execs
+                                    .iter()
+                                    .find(|e| e.tool_call_id == t.tool_call_id)
+                                {
+                                    if let Some(d) = exec.duration_ms() {
+                                        self.tool_durations.insert((off, 0), d);
                                     }
                                 }
                             }
-                            turn += 1;
+                            _ => {}
                         }
                     }
                 }
@@ -529,6 +550,7 @@ impl App {
         self.session_id = None;
         self.last_entry_id = None;
         self.thinking_durations.clear();
+        self.tool_durations.clear();
         self.expanded.clear();
         self.last_usage = None;
         self.notes.clear();
@@ -553,6 +575,7 @@ impl App {
         self.session_id = Some(session_id.to_string());
         self.last_entry_id = entries.last().map(|e| e.id.clone());
         self.thinking_durations.clear();
+        self.tool_durations.clear();
         self.expanded.clear();
         self.notes.clear();
         self.push_note(format!(
@@ -671,20 +694,48 @@ impl App {
             KeyCode::Delete => self.delete(),
             KeyCode::Left => self.move_caret(-1),
             KeyCode::Right => self.move_caret(1),
-            KeyCode::Up => self.move_caret_line(-1),
-            KeyCode::Down => self.move_caret_line(1),
             KeyCode::Home => {
                 self.caret = self.line_start(self.caret);
             }
             KeyCode::End => {
                 self.caret = self.line_end(self.caret);
             }
-            KeyCode::PageUp => self.scroll = self.scroll.saturating_add(10),
+            KeyCode::PageUp => {
+                self.follow = false;
+                self.scroll = self.scroll.saturating_add(self.view_height.max(1));
+                self.scroll = self.scroll.min(self.max_scroll());
+            }
             KeyCode::PageDown => {
-                let max = self.max_scroll();
-                self.scroll = (self.scroll + 10).min(max);
+                self.scroll = (self.scroll + self.view_height.max(1)).min(self.max_scroll());
+                self.follow = self.scroll >= self.max_scroll();
+            }
+            KeyCode::Up => {
+                if self.input.is_empty() {
+                    // 输入为空时 ↑↓ 滚动消息区（否则用于移动光标）。
+                    // Up/Down scroll the messages when the input is empty
+                    // (otherwise they move the caret).
+                    self.follow = false;
+                    self.scroll = self.scroll.saturating_sub(1);
+                } else {
+                    self.move_caret_line(-1);
+                }
+            }
+            KeyCode::Down => {
+                if self.input.is_empty() {
+                    self.scroll = (self.scroll + 1).min(self.max_scroll());
+                    self.follow = self.scroll >= self.max_scroll();
+                } else {
+                    self.move_caret_line(1);
+                }
             }
             KeyCode::Char(c) => {
+                // Ctrl+U 逐行向上滚动（vim 风格）。
+                // Ctrl+U scrolls up line-by-line (vim style).
+                if c == 'u' && key.modifiers.contains(KeyModifiers::CONTROL) {
+                    self.follow = false;
+                    self.scroll = self.scroll.saturating_sub(1);
+                    return false;
+                }
                 // Ctrl+D 继续。
                 // Ctrl+D continues.
                 if c == 'd' && key.modifiers.contains(KeyModifiers::CONTROL) {
diff --git a/crates/focus-tui/src/format.rs b/crates/focus-tui/src/format.rs
index 25987af..b9ee13b 100644
--- a/crates/focus-tui/src/format.rs
+++ b/crates/focus-tui/src/format.rs
@@ -46,6 +46,42 @@ pub fn summarize_tool(name: &str, args: &JsonValue) -> String {
     }
 }
 
+/// 把工具参数格式化为人类可读的多行文本（而非原始 JSON）。
+/// Format tool arguments as human-readable lines (not raw JSON).
+pub fn format_args_human(args: &JsonValue) -> Vec<String> {
+    let mut out = Vec::new();
+    match args {
+        JsonValue::Obj(entries) => {
+            for (k, v) in entries {
+                match v {
+                    JsonValue::Str(s) => out.push(format!("{}: {}", k, s)),
+                    JsonValue::Num(n) => out.push(format!("{}: {}", k, n)),
+                    JsonValue::Bool(b) => out.push(format!("{}: {}", k, b)),
+                    JsonValue::Arr(items) if k == "edits" => {
+                        out.push(format!("{}: 共 {} 处修改", k, items.len()));
+                        for (i, e) in items.iter().enumerate() {
+                            let old_s = e
+                                .get_str("oldString")
+                                .map(|s| truncate(s, 60))
+                                .unwrap_or_else(|| "?".into());
+                            let new_s = e
+                                .get_str("newString")
+                                .map(|s| truncate(s, 60))
+                                .unwrap_or_else(|| "?".into());
+                            out.push(format!("  {}: {}  →  {}", i + 1, old_s, new_s));
+                        }
+                    }
+                    JsonValue::Arr(items) => out.push(format!("{}: [{} 项]", k, items.len())),
+                    JsonValue::Null => out.push(format!("{}: (空)", k)),
+                    _ => out.push(format!("{}: …", k)),
+                }
+            }
+        }
+        _ => out.push(truncate(&focus_json::to_string(args), 200)),
+    }
+    out
+}
+
 /// 格式化耗时（毫秒 → 人类可读）。
 /// Format a duration (ms → human readable).
 pub fn format_duration(ms: u64) -> String {
diff --git a/crates/focus-tui/src/lib.rs b/crates/focus-tui/src/lib.rs
index dc07409..44b902b 100644
--- a/crates/focus-tui/src/lib.rs
+++ b/crates/focus-tui/src/lib.rs
@@ -25,6 +25,9 @@ pub mod format;
 /// 后台任务：运行 agent、自动压缩。
 /// Background jobs: running the agent, auto-compaction.
 pub mod job;
+/// 极简 Markdown 渲染。
+/// Minimal Markdown rendering.
+pub mod markdown;
 /// 纯 UI 状态机：从 Agent 事件构建可渲染的块（可独立测试）。
 /// Pure UI state machine: builds renderable blocks from Agent events
 /// (testable without a terminal).
diff --git a/crates/focus-tui/src/markdown.rs b/crates/focus-tui/src/markdown.rs
new file mode 100644
index 0000000..37dadb2
--- /dev/null
+++ b/crates/focus-tui/src/markdown.rs
@@ -0,0 +1,384 @@
+//! 极简 Markdown 渲染：把 LLM 输出的 markdown 转为带样式的行。
+//! Minimal Markdown rendering: turns LLM markdown into styled lines.
+//!
+//! 手写实现（白名单内无 markdown crate）：支持标题、粗体/斜体、行内代码、
+//! 围栏代码块、列表、引用、链接、分隔线。不追求完整规范，覆盖常见输出即可。
+//! Hand-rolled (no markdown crate in the whitelist): headers, bold/italic,
+//! inline code, fenced code blocks, lists, quotes, links and rules. Not
+//! spec-complete, just enough for typical LLM output.
+
+/// 行级块样式。
+/// Per-line block style.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum MdBlockStyle {
+    /// 普通段落。
+    /// A plain paragraph.
+    Plain,
+    /// 标题（# / ## / ###，级别存于 `level`）。
+    /// A header (level in `level`).
+    Header,
+    /// 引用（>）。
+    /// A blockquote (>).
+    Quote,
+    /// 无序列表项。
+    /// An unordered list item.
+    Bullet,
+    /// 有序列表项。
+    /// An ordered list item.
+    Numbered,
+    /// 围栏代码块中的一行。
+    /// A line inside a fenced code block.
+    CodeBlock,
+    /// 分隔线（---）。
+    /// A horizontal rule (---).
+    Hr,
+    /// 空行。
+    /// A blank line.
+    Blank,
+}
+
+/// 一个带内联样式的文本片段。
+/// One inline-styled text span.
+#[derive(Debug, Clone)]
+pub struct MdSpan {
+    pub text: String,
+    pub bold: bool,
+    pub italic: bool,
+    /// 行内代码（`code`）。
+    /// Inline code (`code`).
+    pub code: bool,
+    /// 链接（[text](url)）。
+    /// A link ([text](url)).
+    pub link: bool,
+}
+
+impl MdSpan {
+    fn plain(text: impl Into<String>) -> Self {
+        Self {
+            text: text.into(),
+            bold: false,
+            italic: false,
+            code: false,
+            link: false,
+        }
+    }
+}
+
+/// 渲染结果的一行。
+/// One rendered line.
+#[derive(Debug, Clone)]
+pub struct MdLine {
+    pub style: MdBlockStyle,
+    /// 标题级别（1-3，仅 Header 有意义）。
+    /// Header level (1-3, meaningful for Header only).
+    pub level: u8,
+    pub spans: Vec<MdSpan>,
+}
+
+/// 把 markdown 渲染为带样式的行（按 `width` 换行）。
+/// Render markdown into styled lines (wrapped at `width`).
+pub fn render_markdown(text: &str, width: usize) -> Vec<MdLine> {
+    let mut out: Vec<MdLine> = Vec::new();
+    let mut in_code = false;
+    for raw in text.lines() {
+        if in_code {
+            if raw.trim().starts_with("```") {
+                in_code = false;
+                continue;
+            }
+            push_code_line(&mut out, raw, width);
+            continue;
+        }
+        let trimmed = raw.trim_start();
+        if trimmed.starts_with("```") {
+            in_code = true;
+            continue;
+        }
+        if trimmed.is_empty() {
+            out.push(MdLine {
+                style: MdBlockStyle::Blank,
+                level: 0,
+                spans: Vec::new(),
+            });
+            continue;
+        }
+        if let Some(level) = header_level(trimmed) {
+            let body = trimmed[level as usize..].trim_start();
+            push_wrapped(
+                &mut out,
+                MdBlockStyle::Header,
+                level,
+                parse_inline(body),
+                width,
+            );
+        } else if let Some(q) = trimmed.strip_prefix(">") {
+            push_wrapped(
+                &mut out,
+                MdBlockStyle::Quote,
+                0,
+                parse_inline(q.trim_start()),
+                width,
+            );
+        } else if is_hr(trimmed) {
+            out.push(MdLine {
+                style: MdBlockStyle::Hr,
+                level: 0,
+                spans: vec![MdSpan::plain("─".repeat(width.max(3)))],
+            });
+        } else if let Some(num) = numbered_prefix(trimmed) {
+            let body = &trimmed[num.len()..];
+            let mut spans = vec![MdSpan::plain(num.to_string())];
+            spans.extend(parse_inline(body.trim_start()));
+            push_wrapped(&mut out, MdBlockStyle::Numbered, 0, spans, width);
+        } else if trimmed.starts_with("- ")
+            || trimmed.starts_with("* ")
+            || trimmed.starts_with("+ ")
+        {
+            let body = &trimmed[2..];
+            let mut spans = vec![MdSpan::plain("• ")];
+            spans.extend(parse_inline(body.trim_start()));
+            push_wrapped(&mut out, MdBlockStyle::Bullet, 0, spans, width);
+        } else {
+            push_wrapped(
+                &mut out,
+                MdBlockStyle::Plain,
+                0,
+                parse_inline(trimmed),
+                width,
+            );
+        }
+    }
+    out
+}
+
+/// 标题级别（返回 1-3，非标题返回 None）。
+/// Header level (1-3, None if not a header).
+fn header_level(s: &str) -> Option<u8> {
+    if s.starts_with("### ") {
+        Some(3)
+    } else if s.starts_with("## ") {
+        Some(2)
+    } else if s.starts_with("# ") {
+        Some(1)
+    } else {
+        None
+    }
+}
+
+/// 是否为分隔线。
+/// Whether the line is a horizontal rule.
+fn is_hr(s: &str) -> bool {
+    let t = s.trim();
+    (t == "---" || t == "***" || t == "___") && t.len() >= 3
+}
+
+/// 有序列表前缀（如 "1."）；非有序列表返回 None。
+/// An ordered-list prefix (e.g. "1."); None otherwise.
+fn numbered_prefix(s: &str) -> Option<&str> {
+    let digits: String = s.chars().take_while(|c| c.is_ascii_digit()).collect();
+    if digits.is_empty() {
+        return None;
+    }
+    let rest = &s[digits.len()..];
+    if rest.starts_with(". ") {
+        Some(&s[..digits.len() + 2])
+    } else {
+        None
+    }
+}
+
+/// 代码块行（整行作为一段文本）。
+/// A code-block line (the whole line as one span).
+fn push_code_line(out: &mut Vec<MdLine>, raw: &str, width: usize) {
+    for line in crate::format::wrap_text(raw, width) {
+        out.push(MdLine {
+            style: MdBlockStyle::CodeBlock,
+            level: 0,
+            spans: vec![MdSpan::plain(line)],
+        });
+    }
+}
+
+/// 按宽度换行推入一行（延续行复用同样的块样式与内联样式）。
+/// Push one line wrapped at `width` (continuation lines keep the block style
+/// and inline styles).
+fn push_wrapped(
+    out: &mut Vec<MdLine>,
+    style: MdBlockStyle,
+    level: u8,
+    spans: Vec<MdSpan>,
+    width: usize,
+) {
+    if spans.is_empty() {
+        out.push(MdLine {
+            style,
+            level,
+            spans,
+        });
+        return;
+    }
+    // 把 spans 拍平成 (字符, 样式) 流，按宽度切行，样式跟随字符。
+    // Flatten spans into a (char, style) stream and cut lines at `width`,
+    // carrying the style along with each char.
+    let width = width.max(1);
+    let mut current: Vec<MdSpan> = Vec::new();
+    let mut w = 0usize;
+    for span in spans {
+        for ch in span.text.chars() {
+            let cw = crate::format::display_width_char(ch);
+            if w + cw > width && w > 0 {
+                out.push(MdLine {
+                    style,
+                    level,
+                    spans: std::mem::take(&mut current),
+                });
+                w = 0;
+            }
+            // 与上一个片段样式相同时合并（避免逐字符成片段）。
+            // Coalesce with the previous fragment when the style matches
+            // (avoid one span per char).
+            let same_style = current.last().map(|last| {
+                last.bold == span.bold
+                    && last.italic == span.italic
+                    && last.code == span.code
+                    && last.link == span.link
+            });
+            if same_style == Some(true) {
+                current.last_mut().expect("last span").text.push(ch);
+            } else {
+                current.push(MdSpan {
+                    text: ch.to_string(),
+                    bold: span.bold,
+                    italic: span.italic,
+                    code: span.code,
+                    link: span.link,
+                });
+            }
+            w += cw;
+        }
+    }
+    if !current.is_empty() {
+        out.push(MdLine {
+            style,
+            level,
+            spans: current,
+        });
+    }
+}
+
+/// 行内解析：**粗体**、*斜体*、`行内代码`、[链接](url)。
+/// Inline parsing: **bold**, *italic*, `inline code`, [link](url).
+fn parse_inline(s: &str) -> Vec<MdSpan> {
+    let mut out = Vec::new();
+    let chars: Vec<char> = s.chars().collect();
+    let mut i = 0usize;
+    let mut plain = String::new();
+    while i < chars.len() {
+        let c = chars[i];
+        if c == '`' {
+            // 行内代码：直到下一个反引号。
+            // Inline code: until the next backtick.
+            if let Some(end) = chars[i + 1..].iter().position(|&x| x == '`') {
+                let end = i + 1 + end;
+                flush_plain(&mut plain, &mut out);
+                let code: String = chars[i + 1..end].iter().collect();
+                out.push(MdSpan {
+                    text: code,
+                    bold: false,
+                    italic: false,
+                    code: true,
+                    link: false,
+                });
+                i = end + 1;
+                continue;
+            }
+            plain.push(c);
+            i += 1;
+            continue;
+        }
+        if c == '[' {
+            // 链接 [text](url)。
+            // A link [text](url).
+            if let Some(close) = chars[i + 1..].iter().position(|&x| x == ']') {
+                let close = i + 1 + close;
+                let after = close + 1;
+                if after < chars.len() && chars[after] == '(' {
+                    if let Some(paren) = chars[after + 1..].iter().position(|&x| x == ')') {
+                        let paren = after + 1 + paren;
+                        flush_plain(&mut plain, &mut out);
+                        let text: String = chars[i + 1..close].iter().collect();
+                        out.push(MdSpan {
+                            text,
+                            bold: false,
+                            italic: false,
+                            code: false,
+                            link: true,
+                        });
+                        i = paren + 1;
+                        continue;
+                    }
+                }
+            }
+            plain.push(c);
+            i += 1;
+            continue;
+        }
+        if c == '*' {
+            // **粗体** 或 *斜体*。
+            // **bold** or *italic*.
+            if i + 1 < chars.len() && chars[i + 1] == '*' {
+                if let Some(end) = chars[i + 2..]
+                    .windows(2)
+                    .position(|w| w[0] == '*' && w[1] == '*')
+                {
+                    let end = i + 2 + end;
+                    flush_plain(&mut plain, &mut out);
+                    let inner: String = chars[i + 2..end].iter().collect();
+                    out.push(MdSpan {
+                        text: inner,
+                        bold: true,
+                        italic: false,
+                        code: false,
+                        link: false,
+                    });
+                    i = end + 2;
+                    continue;
+                }
+            }
+            if let Some(end) = chars[i + 1..].iter().position(|&x| x == '*') {
+                let end = i + 1 + end;
+                // 避免把 ** 误判为斜体：若该段以 * 结尾（如 **x** 的前半）则跳过。
+                // Avoid mistaking ** for italic: skip if the segment ends with
+                // a star (e.g. the first half of **x**).
+                if end > i + 1 && chars[end - 1] != '*' {
+                    flush_plain(&mut plain, &mut out);
+                    let inner: String = chars[i + 1..end].iter().collect();
+                    out.push(MdSpan {
+                        text: inner,
+                        bold: false,
+                        italic: true,
+                        code: false,
+                        link: false,
+                    });
+                    i = end + 1;
+                    continue;
+                }
+            }
+            plain.push(c);
+            i += 1;
+            continue;
+        }
+        plain.push(c);
+        i += 1;
+    }
+    flush_plain(&mut plain, &mut out);
+    out
+}
+
+/// 把累积的纯文本推入输出。
+/// Flush accumulated plain text into the output.
+fn flush_plain(plain: &mut String, out: &mut Vec<MdSpan>) {
+    if !plain.is_empty() {
+        out.push(MdSpan::plain(std::mem::take(plain)));
+    }
+}
diff --git a/crates/focus-tui/src/state.rs b/crates/focus-tui/src/state.rs
index b980b37..baeda52 100644
--- a/crates/focus-tui/src/state.rs
+++ b/crates/focus-tui/src/state.rs
@@ -75,6 +75,7 @@ pub enum UiBlock {
         name: String,
         text: String,
         is_error: bool,
+        duration_ms: Option<u64>,
         expanded: bool,
     },
     /// 运行错误（assistant 消息的 error_message，红色显示）。
@@ -324,6 +325,13 @@ impl RunState {
         "working…".to_string()
     }
 
+    /// 当前 assistant 消息已提交进 transcript：清空 partial，避免重复显示。
+    /// The current assistant message was committed to the transcript: clear
+    /// the partial to avoid double-rendering.
+    pub fn commit_partial(&mut self) {
+        self.partial = None;
+    }
+
     /// 消息结束时收尾未结算的思考计时。
     /// Finalize unsettled thinking timings at message end.
     pub fn finalize(&mut self) {
@@ -356,6 +364,7 @@ fn join_text(blocks: &[ContentBlock]) -> String {
 pub fn build_blocks(
     transcript: &[Message],
     thinking_durations: &std::collections::HashMap<(usize, usize), u64>,
+    tool_durations: &std::collections::HashMap<(usize, usize), u64>,
     run_state: Option<&RunState>,
     expanded: &HashSet<BlockId>,
 ) -> Vec<UiBlock> {
@@ -400,6 +409,7 @@ pub fn build_blocks(
                     name: t.tool_name.clone(),
                     text: join_text(&t.content),
                     is_error: t.is_error,
+                    duration_ms: tool_durations.get(&(mi, 0)).copied(),
                     expanded: expanded.contains(&BlockId(format!("m{}-r", mi))),
                 });
             }
@@ -432,7 +442,16 @@ pub fn build_blocks(
                 });
             }
         }
-        for (ei, exec) in rs.tool_execs.iter().enumerate() {
+        // 只显示仍在运行的工具执行（已结束的由 transcript 中的 tool_result
+        // 消息呈现，避免重复）。
+        // Only running tool executions are shown live; finished ones are
+        // presented by the transcript's tool_result messages (no duplicates).
+        for (ei, exec) in rs
+            .tool_execs
+            .iter()
+            .enumerate()
+            .filter(|(_, e)| e.status == ExecStatus::Running)
+        {
             out.push(UiBlock::ToolExec {
                 id: BlockId(format!("exec-{}", ei)),
                 name: exec.name.clone(),
diff --git a/crates/focus-tui/src/ui.rs b/crates/focus-tui/src/ui.rs
index 93462d2..10f7f59 100644
--- a/crates/focus-tui/src/ui.rs
+++ b/crates/focus-tui/src/ui.rs
@@ -2,13 +2,14 @@
 //! Terminal rendering and the main loop (ratatui + crossterm).
 
 use crate::app::{App, BlockGeometry, ConfigForm, FormField, Modal};
-use crate::format::{format_duration, format_tokens, truncate, wrap_text};
+use crate::format::{format_args_human, format_duration, format_tokens, truncate, wrap_text};
+use crate::markdown::{render_markdown, MdBlockStyle, MdLine};
 use crate::state::{ExecStatus, UiBlock};
 use focus_harness::estimate_messages;
 use focus_providers::config::resolve_context_window;
 use ratatui::backend::CrosstermBackend;
 use ratatui::layout::{Alignment, Constraint, Layout, Margin, Position, Rect};
-use ratatui::style::{Color, Style};
+use ratatui::style::{Color, Modifier, Style};
 use ratatui::text::{Line, Span, Text};
 use ratatui::widgets::{Block, Borders, Paragraph, Wrap};
 use ratatui::{Frame, Terminal};
@@ -137,6 +138,7 @@ fn draw_messages(frame: &mut Frame, area: Rect, app: &mut App) {
     blocks.extend(crate::state::build_blocks(
         &app.transcript,
         &app.thinking_durations,
+        &app.tool_durations,
         app.run_state.as_ref(),
         &app.expanded,
     ));
@@ -236,9 +238,9 @@ fn block_lines(block: &UiBlock, width: usize) -> Vec<Line<'static>> {
             out.push(Line::from(Span::styled(meta, dim)));
         }
         UiBlock::Text { text, .. } => {
-            for line in wrap_text(text, width) {
-                out.push(Line::from(Span::raw(line)));
-            }
+            // LLM 输出多为 markdown：按块样式渲染。
+            // LLM output is usually markdown: render it with block styles.
+            out.extend(markdown_lines(text, width));
         }
         UiBlock::Thinking {
             text,
@@ -291,9 +293,12 @@ fn block_lines(block: &UiBlock, width: usize) -> Vec<Line<'static>> {
                     format!("▾ 🔧 {}", name),
                     Style::new().fg(Color::Magenta).bold(),
                 )));
-                let json = focus_json::to_string(args);
-                for line in wrap_text(&json, width.saturating_sub(2)) {
-                    out.push(Line::from(Span::styled(format!("  {}", line), dim)));
+                // 人类可读的参数（非原始 JSON）。
+                // Human-readable arguments (not raw JSON).
+                for line in format_args_human(args) {
+                    for wrapped in wrap_text(&line, width.saturating_sub(2)) {
+                        out.push(Line::from(Span::styled(format!("  {}", wrapped), dim)));
+                    }
                 }
             } else {
                 out.push(Line::from(Span::styled(
@@ -306,13 +311,18 @@ fn block_lines(block: &UiBlock, width: usize) -> Vec<Line<'static>> {
             name,
             text,
             is_error,
+            duration_ms,
             expanded,
             ..
         } => {
             let mark = if *is_error { "✗" } else { "✓" };
+            let dur = duration_ms
+                .map(format_duration)
+                .map(|d| format!(" · {}", d))
+                .unwrap_or_default();
             if *expanded {
                 out.push(Line::from(Span::styled(
-                    format!("▾ 📦 {} {}", mark, name),
+                    format!("▾ 📦 {} {}{}", mark, name, dur),
                     if *is_error {
                         Style::new().fg(Color::Red).bold()
                     } else {
@@ -324,7 +334,7 @@ fn block_lines(block: &UiBlock, width: usize) -> Vec<Line<'static>> {
                 }
             } else {
                 out.push(Line::from(Span::styled(
-                    format!("▸ 📦 {} {}（点击/Tab 展开）", mark, name),
+                    format!("▸ 📦 {} {}{}（点击/Tab 展开）", mark, name, dur),
                     if *is_error {
                         Style::new().fg(Color::Red)
                     } else {
@@ -524,7 +534,7 @@ focus — 终端编码 agent
 中止：Esc（运行中）；退出：Esc（空闲）/ Ctrl+C
 继续：Ctrl+D（对最后一条 assistant 消息再追问）
 展开/折叠：点击思考/工具块，或 Tab 切换最近一个
-滚动：PageUp / PageDown / 鼠标滚轮
+滚动：↑↓（输入为空时）/ Ctrl+U / PageUp·PageDown / 鼠标滚轮
 
 命令：
   /new       新会话
@@ -612,3 +622,51 @@ fn draw_sessions_modal(frame: &mut Frame, area: Rect, form: &crate::app::Session
 }
 
 // emphasis.
+
+/// 把 markdown 渲染为 ratatui 行。
+/// Render markdown into ratatui lines.
+fn markdown_lines(text: &str, width: usize) -> Vec<Line<'static>> {
+    let lines = render_markdown(text, width);
+    let mut out = Vec::new();
+    for md in lines {
+        out.push(md_line_to_ratatui(&md));
+    }
+    out
+}
+
+/// 把一条渲染后的 markdown 行映射为 ratatui 行。
+/// Map one rendered markdown line to a ratatui line.
+fn md_line_to_ratatui(md: &MdLine) -> Line<'static> {
+    let block_style: Style = match md.style {
+        MdBlockStyle::Header => match md.level {
+            1 => Style::new().fg(Color::Cyan).bold(),
+            2 => Style::new().fg(Color::Cyan),
+            _ => Style::new().fg(Color::Yellow),
+        },
+        MdBlockStyle::CodeBlock => Style::new().fg(Color::DarkGray),
+        MdBlockStyle::Quote => Style::new().fg(Color::DarkGray),
+        MdBlockStyle::Hr | MdBlockStyle::Blank => Style::new().fg(Color::DarkGray),
+        MdBlockStyle::Bullet | MdBlockStyle::Numbered | MdBlockStyle::Plain => Style::new(),
+    };
+    let spans: Vec<Span> = md
+        .spans
+        .iter()
+        .map(|sp| {
+            let mut style = block_style;
+            if sp.bold {
+                style = style.add_modifier(Modifier::BOLD);
+            }
+            if sp.italic {
+                style = style.add_modifier(Modifier::ITALIC);
+            }
+            if sp.code {
+                style = style.fg(Color::Yellow);
+            }
+            if sp.link {
+                style = style.fg(Color::Blue).add_modifier(Modifier::UNDERLINED);
+            }
+            Span::styled(sp.text.clone(), style)
+        })
+        .collect();
+    Line::from(spans)
+}
diff --git a/crates/focus-tui/tests/format_tests.rs b/crates/focus-tui/tests/format_tests.rs
index 7d3bf6f..b681d4f 100644
--- a/crates/focus-tui/tests/format_tests.rs
+++ b/crates/focus-tui/tests/format_tests.rs
@@ -108,3 +108,34 @@ fn caret_positioning() {
     let (row, col, total) = caret_position("aaaaaa", 6, 3);
     assert_eq!((row, col, total), (1, 3, 2));
 }
+
+#[test]
+fn args_human_format_no_raw_json() {
+    use focus_tui::format::format_args_human;
+
+    // shell：命令按原样。
+    // shell: the command verbatim.
+    let args = obj(&[("command", "ls -la".into())]);
+    assert_eq!(
+        format_args_human(&args),
+        vec!["command: ls -la".to_string()]
+    );
+
+    // read：路径。
+    // read: the path.
+    let args = obj(&[("path", "/a/b.txt".into())]);
+    assert_eq!(format_args_human(&args), vec!["path: /a/b.txt".to_string()]);
+
+    // edit：多组修改以人类可读展示（非 JSON）。
+    // edit: multiple edits shown human-readably (not JSON).
+    let mut e1 = JsonValue::obj();
+    e1.insert("oldString", "foo".into()).ok();
+    e1.insert("newString", "bar".into()).ok();
+    let edits = JsonValue::Arr(vec![e1]);
+    let args = obj(&[("path", "f.txt".into()), ("edits", edits)]);
+    let lines = format_args_human(&args);
+    assert_eq!(lines[0], "path: f.txt");
+    assert_eq!(lines[1], "edits: 共 1 处修改");
+    assert!(lines[2].contains("foo"), "got {:?}", lines);
+    assert!(lines[2].contains("bar"), "got {:?}", lines);
+}
diff --git a/crates/focus-tui/tests/markdown_tests.rs b/crates/focus-tui/tests/markdown_tests.rs
new file mode 100644
index 0000000..4c44395
--- /dev/null
+++ b/crates/focus-tui/tests/markdown_tests.rs
@@ -0,0 +1,83 @@
+//! 极简 Markdown 渲染器的测试。
+//! Tests for the minimal Markdown renderer.
+
+use focus_tui::markdown::{render_markdown, MdBlockStyle, MdLine};
+
+fn text_of(md: &MdLine) -> String {
+    md.spans.iter().map(|s| s.text.as_str()).collect()
+}
+
+fn join(lines: &[MdLine]) -> Vec<String> {
+    lines.iter().map(text_of).collect()
+}
+
+#[test]
+fn renders_headers() {
+    let out = render_markdown("# Title\n## Sub\n### Deep\nplain", 80);
+    assert_eq!(out[0].style, MdBlockStyle::Header);
+    assert_eq!(out[0].level, 1);
+    assert_eq!(text_of(&out[0]), "Title");
+    assert_eq!(out[1].level, 2);
+    assert_eq!(out[2].level, 3);
+    assert_eq!(out[3].style, MdBlockStyle::Plain);
+}
+
+#[test]
+fn renders_bold_italic_and_code() {
+    let out = render_markdown("**bold** and *italic* and `code`", 80);
+    let line = &out[0];
+    // 5 段：bold, " and ", italic, " and ", code。
+    // 5 spans: bold, " and ", italic, " and ", code.
+    assert_eq!(line.spans.len(), 5);
+    let bold = line.spans.iter().find(|s| s.bold).expect("bold span");
+    assert_eq!(bold.text, "bold");
+    let italic = line.spans.iter().find(|s| s.italic).expect("italic span");
+    assert_eq!(italic.text, "italic");
+    let code = line.spans.iter().find(|s| s.code).expect("code span");
+    assert_eq!(code.text, "code");
+}
+
+#[test]
+fn renders_fenced_code_blocks() {
+    let md = "```rust\nfn main() {}\n```\nafter";
+    let out = render_markdown(md, 80);
+    assert_eq!(out[0].style, MdBlockStyle::CodeBlock);
+    assert_eq!(text_of(&out[0]), "fn main() {}");
+    assert_eq!(out[1].style, MdBlockStyle::Plain);
+    assert_eq!(text_of(&out[1]), "after");
+}
+
+#[test]
+fn renders_lists_and_quotes() {
+    let md = "- item a\n- item b\n1. first\n2. second\n> quote text";
+    let out = render_markdown(md, 80);
+    let joined = join(&out);
+    assert_eq!(joined[0], "• item a");
+    assert_eq!(joined[1], "• item b");
+    assert_eq!(joined[2], "1. first");
+    assert_eq!(joined[3], "2. second");
+    assert_eq!(out[4].style, MdBlockStyle::Quote);
+    assert_eq!(text_of(&out[4]), "quote text");
+}
+
+#[test]
+fn renders_links_and_hr() {
+    let out = render_markdown("see [docs](https://example.com)\n---", 80);
+    let link = out[0].spans.iter().find(|s| s.link).expect("link span");
+    assert_eq!(link.text, "docs");
+    assert_eq!(out[1].style, MdBlockStyle::Hr);
+}
+
+#[test]
+fn wraps_at_width() {
+    let out = render_markdown("aaaaaa bbbbbb cccccc", 8);
+    let joined = join(&out);
+    assert!(joined.len() >= 2, "got {:?}", joined);
+    for line in &joined {
+        assert!(
+            focus_tui::format::display_width(line) <= 8,
+            "line too wide: {:?}",
+            line
+        );
+    }
+}
diff --git a/crates/focus-tui/tests/state_tests.rs b/crates/focus-tui/tests/state_tests.rs
index f7caee8..74d60e4 100644
--- a/crates/focus-tui/tests/state_tests.rs
+++ b/crates/focus-tui/tests/state_tests.rs
@@ -151,7 +151,13 @@ fn blocks_are_collapsed_by_default_and_summarized() {
             }),
         ])),
     ];
-    let blocks = build_blocks(&transcript, &HashMap::new(), None, &expanded);
+    let blocks = build_blocks(
+        &transcript,
+        &HashMap::new(),
+        &HashMap::new(),
+        None,
+        &expanded,
+    );
 
     // 折叠态：思考块只显示摘要（无展开文本），工具调用只显示摘要。
     // Collapsed: thinking shows only its summary; tool calls show only their
@@ -185,7 +191,13 @@ fn blocks_are_collapsed_by_default_and_summarized() {
             toggle_expanded(&mut expanded, id);
         }
     }
-    let blocks = build_blocks(&transcript, &HashMap::new(), None, &expanded);
+    let blocks = build_blocks(
+        &transcript,
+        &HashMap::new(),
+        &HashMap::new(),
+        None,
+        &expanded,
+    );
     let mut expanded_count = 0;
     for b in &blocks {
         if let UiBlock::Thinking { expanded, .. } | UiBlock::ToolCall { expanded, .. } = b {
@@ -212,7 +224,13 @@ fn build_blocks_includes_live_run() {
         event_type: "text_start".into(),
     });
 
-    let blocks = build_blocks(&[], &HashMap::new(), Some(&rs), &HashSet::new());
+    let blocks = build_blocks(
+        &[],
+        &HashMap::new(),
+        &HashMap::new(),
+        Some(&rs),
+        &HashSet::new(),
+    );
     // live 头 + 思考 + 文本。
     // live header + thinking + text.
     let thinking = blocks
@@ -292,7 +310,13 @@ fn error_message_renders_as_error_block() {
         error_message: Some("http error 400: bad request detail".into()),
         timestamp: 0,
     })];
-    let blocks = build_blocks(&transcript, &HashMap::new(), None, &HashSet::new());
+    let blocks = build_blocks(
+        &transcript,
+        &HashMap::new(),
+        &HashMap::new(),
+        None,
+        &HashSet::new(),
+    );
     let err = blocks
         .iter()
         .find_map(|b| match b {
@@ -302,3 +326,108 @@ fn error_message_renders_as_error_block() {
         .expect("error block");
     assert_eq!(err, "http error 400: bad request detail");
 }
+
+/// commit_partial 清空流式 partial（消息已提交进 transcript 后避免重复显示）。
+/// commit_partial clears the streaming partial (avoids double-rendering once
+/// the message is committed into the transcript).
+#[test]
+fn commit_partial_clears_live_message() {
+    let fc = FakeClock::new();
+    let mut rs = RunState::new(fc.clock());
+    rs.on_agent_event(&AgentEvent::MessageStart {
+        message: Message::Assistant(assistant(vec![ContentBlock::text("hi")])),
+    });
+    assert!(rs.partial.is_some());
+    rs.commit_partial();
+    assert!(rs.partial.is_none());
+}
+
+/// 已提交 tool_result 消息的耗时进入摘要行。
+/// A committed tool_result's duration reaches its summary.
+#[test]
+fn tool_duration_shows_in_tool_result_block() {
+    let transcript = vec![Message::ToolResult(ToolResultMessage {
+        tool_call_id: "c1".into(),
+        tool_name: "shell".into(),
+        content: vec![ContentBlock::text("ok")],
+        details: JsonValue::obj(),
+        is_error: false,
+        timestamp: 0,
+    })];
+    let mut durations = HashMap::new();
+    durations.insert((0usize, 0usize), 12345u64);
+    let blocks = build_blocks(
+        &transcript,
+        &HashMap::new(),
+        &durations,
+        None,
+        &HashSet::new(),
+    );
+    let tr = blocks.iter().find_map(|b| match b {
+        UiBlock::ToolResult { duration_ms, .. } => Some(*duration_ms),
+        _ => None,
+    });
+    assert_eq!(tr, Some(Some(12_345)));
+}
+
+/// 流式视图只显示运行中的工具执行（已结束的由 transcript 呈现）。
+/// The live view only shows running tool executions (finished ones are
+/// presented by the transcript).
+#[test]
+fn live_renders_only_running_execs() {
+    let fc = FakeClock::new();
+    let mut rs = RunState::new(fc.clock());
+    let mut args = JsonValue::obj();
+    args.insert("command", "cargo test".into()).ok();
+    rs.on_agent_event(&AgentEvent::ToolExecutionStart {
+        tool_call_id: "c1".into(),
+        tool_name: "shell".into(),
+        args,
+    });
+    rs.on_agent_event(&AgentEvent::ToolExecutionEnd {
+        tool_call_id: "c1".into(),
+        tool_name: "shell".into(),
+        result: ToolResult::text("done"),
+        is_error: false,
+    });
+    // 全部结束 → 不渲染任何执行块。
+    // All finished → no execution blocks rendered.
+    let blocks = build_blocks(
+        &[],
+        &HashMap::new(),
+        &HashMap::new(),
+        Some(&rs),
+        &HashSet::new(),
+    );
+    assert!(
+        !blocks.iter().any(|b| matches!(b, UiBlock::ToolExec { .. })),
+        "finished execs must not render live"
+    );
+
+    // 一个新的运行中工具 → 渲染。
+    // A new running tool → rendered.
+    let mut args = JsonValue::obj();
+    args.insert("command", "sleep 1".into()).ok();
+    rs.on_agent_event(&AgentEvent::ToolExecutionStart {
+        tool_call_id: "c2".into(),
+        tool_name: "shell".into(),
+        args,
+    });
+    let blocks = build_blocks(
+        &[],
+        &HashMap::new(),
+        &HashMap::new(),
+        Some(&rs),
+        &HashSet::new(),
+    );
+    assert!(
+        blocks.iter().any(|b| matches!(
+            b,
+            UiBlock::ToolExec {
+                status: ExecStatus::Running,
+                ..
+            }
+        )),
+        "running exec must render"
+    );
+}