diff --git a/src/components/Conversation.tsx b/src/components/Conversation.tsx
index a347a43..42511a2 100644
--- a/src/components/Conversation.tsx
+++ b/src/components/Conversation.tsx
@@ -7,7 +7,8 @@ import type { Message, Part, HITLCard } from '../contracts'
 import { UIRenderer, InlineConfirmCard, hasOpenConfirm } from '@ui'
 import { docBridge } from './Workbench'
 
-marked.setOptions({ breaks: true })
+// marked 走标准 Markdown 语义（不开 breaks）：模型输出按块级排版渲染，
+// 行内换行交给段落折叠，避免与 CSS 块间距叠加出松散排版。
 
 // Part 渲染器注册表：按类型查表；未知类型静默忽略（前向兼容）。
 function PartView({ part, live }: { part: Part; live?: boolean | null }) {
@@ -16,7 +17,13 @@ function PartView({ part, live }: { part: Part; live?: boolean | null }) {
       return <div className={live ? 'part-text cursor-blink' : 'part-text'}
         dangerouslySetInnerHTML={{ __html: marked.parse(part.text ?? '') }} />
     case 'thinking':
-      return <div className="part-thinking">{part.text}</div>
+      // 流式期间展开可实时看到思考；run 终态后收进过程折叠区，默认收起。
+      return (
+        <details className="part-thinking" open={live ? true : undefined}>
+          <summary>思考过程</summary>
+          <div className="part-thinking-body">{part.text}</div>
+        </details>
+      )
     case 'tool_call':
       return <span className="tool-chip">🛠 {part.toolCall?.name}</span>
     case 'tool_result': {
@@ -93,7 +100,7 @@ function AssistantMessage({ msg, live }: { msg: Message; live?: LiveState | null
         {live && <span className="live-bar"><span className="live-dot" />{live.phase}</span>}
       </div>
       {split.process.length > 0 && (showProcessInline
-        ? split.process.map((p, i) => <div className="part" key={i}><PartView part={p} /></div>)
+        ? split.process.map((p, i) => <div className="part" key={i}><PartView part={p} live={!!live} /></div>)
         : <ProcessCollapse parts={split.process} />)}
       {split.content.map((p, i) => <div className="part" key={i}><PartView part={p} live={!!(live && i === split.content.length - 1 && p.type === 'text')} /></div>)}
       {live && <LiveAgentNotes live={live} />}
@@ -102,6 +109,22 @@ function AssistantMessage({ msg, live }: { msg: Message; live?: LiveState | null
   )
 }
 
+// live 投影：run 进行中没有已落库的助手消息，把 LiveState 合成为同构的临时消息
+// 复用 AssistantMessage 渲染（思考/工具/文本实时上屏）；run 终态对账后由真消息替代。
+function liveToMessage(live: LiveState): Message {
+  const parts: Part[] = []
+  if (live.thinking) parts.push({ type: 'thinking', text: live.thinking, process: true })
+  for (const tc of live.toolCalls) {
+    parts.push({ type: 'tool_call', process: true, toolCall: { id: '', name: tc.name } })
+    if (tc.status !== undefined) {
+      parts.push({ type: 'tool_result', process: true, toolCall: { id: '', name: tc.name },
+        toolResult: { callId: '', status: tc.status === 'error' ? 'error' : 'ok', summary: tc.summary } })
+    }
+  }
+  if (live.text) parts.push({ type: 'text', text: live.text })
+  return { id: `live:${live.runId}`, conversationId: '', role: 'assistant', runId: live.runId, parts, createdAt: '' }
+}
+
 // 上下文组装观测（4.10/4.17）：模型实际看到什么、裁了什么——可解释性入口。
 function ContextObsView({ obs }: { obs: ContextObs }) {
   return (
@@ -212,7 +235,7 @@ export function Conversation() {
 
   useEffect(() => {
     bodyRef.current?.scrollTo({ top: bodyRef.current.scrollHeight })
-  }, [messages.length, live?.text, live?.thinking, activeHitl.length])
+  }, [messages.length, live?.text, live?.thinking, live?.toolCalls.length, live?.phase, activeHitl.length])
 
   const send = async () => {
     if (!text.trim() && attachmentIds.length === 0) return
@@ -279,6 +302,8 @@ export function Conversation() {
           }
           return <AssistantMessage key={m.id} msg={m} live={live?.runId === m.runId ? live : null} />
         })}
+        {live && !messages.some(m => m.runId === live.runId) &&
+          <AssistantMessage key={`live-${live.runId}`} msg={liveToMessage(live)} live={live} />}
         {activeHitl.map(c => <HITLCardView key={c.id} card={c} />)}
         {messages.length === 0 && <div className="empty-state">
           <div>发送消息开始对话</div>
diff --git a/src/store.ts b/src/store.ts
index 24422e7..48cda25 100644
--- a/src/store.ts
+++ b/src/store.ts
@@ -308,10 +308,12 @@ export const store = {
         return
       }
       if (out.run) {
-        set({
-          live: { runId: out.run.id, phase: 'thinking', thinking: '', text: '', toolCalls: [], agentNotes: {}, startedAt: Date.now() },
-          messages: [...state.messages, out.message],
-        })
+        // 竞态保护：POST 返回前 SSE 事件可能已先行到达并累积（同 run），
+        // 此时保留已累积的 live，只补挂用户消息；否则初始化空 live。
+        if (!state.live || state.live.runId !== out.run.id) {
+          set({ live: { runId: out.run.id, phase: 'thinking', thinking: '', text: '', toolCalls: [], agentNotes: {}, startedAt: Date.now() } })
+        }
+        set({ messages: [...state.messages, out.message] })
         store.connectIfNeeded()
       }
     } catch (e) {
diff --git a/src/styles.css b/src/styles.css
index 6bea78a..00571b9 100644
--- a/src/styles.css
+++ b/src/styles.css
@@ -50,16 +50,35 @@ button { font-family: inherit; }
 .msg-role { font-size: 12px; color: var(--text-faint); margin-bottom: 4px; display: flex; gap: 8px; align-items: center; }
 .msg.user .bubble { background: var(--accent-soft); border: 1px solid var(--border); border-radius: var(--radius); padding: 10px 14px; white-space: pre-wrap; }
 .part { margin: 4px 0; }
-.part-thinking { color: var(--text-faint); font-size: 13px; border-left: 2px solid var(--border); padding-left: 10px; white-space: pre-wrap; }
+.part-thinking { color: var(--text-dim); font-size: 12.5px; border-left: 2px solid var(--border); padding-left: 10px; margin: 4px 0; }
+.part-thinking summary { cursor: pointer; color: var(--text-faint); user-select: none; }
+.part-thinking .part-thinking-body { white-space: pre-wrap; margin-top: 4px; }
 .part-tool { font-size: 12.5px; }
 .tool-chip { display: inline-flex; gap: 6px; align-items: center; background: var(--bg-raised); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 4px 8px; margin: 2px 4px 2px 0; font-family: var(--mono); }
 .tool-chip .status-ok { color: var(--ok); }
 .tool-chip .status-error { color: var(--err); }
-.part-text { white-space: pre-wrap; line-height: 1.7; }
-.part-text :is(h1,h2,h3) { margin: 0.6em 0 0.3em; }
+.part-text { line-height: 1.65; overflow-wrap: break-word; }
+/* 块级间距只由标签自身控制：禁用 pre-wrap（marked 输出的块间换行会被渲染成空行，
+   叠加出"列表逐项空一行"的松散排版）；行内换行语义交给 Markdown 段落。 */
+.part-text > *:first-child { margin-top: 0; }
+.part-text > *:last-child { margin-bottom: 0; }
+.part-text p { margin: 0.5em 0; }
+.part-text :is(h1,h2,h3,h4) { margin: 0.8em 0 0.35em; line-height: 1.35; font-weight: 600; }
+.part-text h1 { font-size: 1.3em; }
+.part-text h2 { font-size: 1.18em; }
+.part-text h3 { font-size: 1.06em; }
+.part-text :is(ul,ol) { margin: 0.4em 0; padding-left: 1.6em; }
+.part-text li { margin: 0.15em 0; }
+.part-text li > p { margin: 0.2em 0; }
 .part-text pre { background: var(--bg-raised); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 10px; overflow-x: auto; font-family: var(--mono); font-size: 12.5px; }
 .part-text code { font-family: var(--mono); background: var(--bg-raised); border-radius: 4px; padding: 1px 5px; font-size: 12.5px; }
-.part-text :is(p,ul,ol) { margin: 0.4em 0; }
+.part-text pre code { background: none; padding: 0; }
+.part-text blockquote { margin: 0.5em 0; padding: 0.1em 0 0.1em 10px; border-left: 3px solid var(--border); color: var(--text-dim); }
+.part-text table { border-collapse: collapse; margin: 0.6em 0; font-size: 0.95em; display: block; max-width: 100%; overflow-x: auto; }
+.part-text th, .part-text td { border: 1px solid var(--border); padding: 4px 10px; text-align: left; }
+.part-text th { background: var(--bg-raised); font-weight: 600; }
+.part-text hr { border: none; border-top: 1px solid var(--border); margin: 0.8em 0; }
+.part-text a { color: var(--accent); }
 .part-error { color: var(--err); background: color-mix(in srgb, var(--err) 8%, transparent); border: 1px solid var(--err); border-radius: var(--radius-sm); padding: 8px 12px; }
 .artifact-chip { display: inline-flex; align-items: center; gap: 6px; color: var(--accent); background: var(--accent-soft); border-radius: var(--radius-sm); padding: 4px 10px; cursor: pointer; font-size: 13px; }
 .artifact-chip:hover { filter: brightness(1.15); }