fix: 在对话里展示模型思考，并在一轮结束后收起

docs/architecture.md

@@ -331,7 +331,7 @@ Handler 直接依赖 `*sqlite.Queries`，不经过 Store 接口。Git 带 `sessi
 
 ### `packages/core`
 
-跨端无头业务，无 UI。按业务域拆目录，文件直接放在 `packages/core/<domain>/`，不要 `src/`。现有 `chat/`：Session / Message / Run / 审批的 HTTP、SSE、Timeline reducer。Git 前端在 `git/`（`GitClient`，不扩 `AgentClient`）。Codex 前端在 `codex/`（`CodexClient`，不扩 `AgentClient`）。Claude 前端在 `claude/`（`ClaudeClient`，不扩 `AgentClient`）。看板前端在 `board/`（`BoardClient`，不扩 `AgentClient`）。`baseUrl` / `userId` 由调用方注入。不依赖 React。thinking 用 Run 状态（`queued` / `loading_context` / `running_llm` / `verifying`），不是模型 reasoning token。验证另有独立时间线卡片；跳过验证不画卡片。
+跨端无头业务，无 UI。按业务域拆目录，文件直接放在 `packages/core/<domain>/`，不要 `src/`。现有 `chat/`：Session / Message / Run / 审批的 HTTP、SSE、Timeline reducer。Git 前端在 `git/`（`GitClient`，不扩 `AgentClient`）。Codex 前端在 `codex/`（`CodexClient`，不扩 `AgentClient`）。Claude 前端在 `claude/`（`ClaudeClient`，不扩 `AgentClient`）。看板前端在 `board/`（`BoardClient`，不扩 `AgentClient`）。`baseUrl` / `userId` 由调用方注入。不依赖 React。thinking 状态字用 Run 状态（`queued` / `loading_context` / `running_llm` / `verifying`）。模型思考正文走 `assistant.delta` 的 `reasoning` 字段，落在助手消息 Content 里供下一轮回传。验证另有独立时间线卡片；跳过验证不画卡片。
 
 ### `packages/ui`
 

packages/core/chat/content.ts

@@ -33,9 +33,11 @@ export function firstLine(text: string, max = 48): string {
 
 export type ParsedDelta =
   | { kind: "text"; text: string }
+  | { kind: "reasoning"; text: string }
   | { kind: "tool"; call: ToolCall }
   | { kind: "unknown" };
 
+// parseDelta 把 assistant.delta 分成正文、思考或工具调用。
 export function parseDelta(delta: unknown): ParsedDelta {
   if (!delta || typeof delta !== "object") {
     return { kind: "unknown" };
@@ -52,6 +54,9 @@ export function parseDelta(delta: unknown): ParsedDelta {
       },
     };
   }
+  if (typeof obj.reasoning === "string") {
+    return { kind: "reasoning", text: obj.reasoning };
+  }
   if (typeof obj.text === "string") {
     return { kind: "text", text: obj.text };
   }

packages/core/chat/reducer.test.ts

@@ -279,6 +279,52 @@ test("assistant deltas concatenate and hide thinking after text", () => {
   assert.equal(assistant.streaming, true);
 });
 
+test("reasoning deltas concatenate and survive later text and completion", () => {
+  let state = applyEvent(
+    emptyState(),
+    ev({
+      seq: 1,
+      type: "run.state_changed",
+      payload: { from: "queued", to: "running_llm", reason: "" },
+    }),
+  );
+  state = applyEvent(state, ev({ seq: 2, type: "assistant.started", payload: { message_id: "a1" } }));
+  state = applyEvent(
+    state,
+    ev({ seq: 3, type: "assistant.delta", payload: { message_id: "a1", delta: { reasoning: "think " } } }),
+  );
+  assert.equal(state.items.some((item) => item.kind === "thinking"), false);
+  state = applyEvent(
+    state,
+    ev({ seq: 4, type: "assistant.delta", payload: { message_id: "a1", delta: { reasoning: "first" } } }),
+  );
+  state = applyEvent(
+    state,
+    ev({ seq: 5, type: "assistant.delta", payload: { message_id: "a1", delta: { text: "pong" } } }),
+  );
+  let assistant = state.items.find((item) => item.kind === "assistant");
+  assert.ok(assistant && assistant.kind === "assistant");
+  assert.equal(assistant.reasoning, "think first");
+  assert.equal(assistant.text, "pong");
+  state = applyEvent(
+    state,
+    ev({
+      seq: 6,
+      type: "assistant.completed",
+      payload: { message_id: "a1", text: "pong", reasoning: "think first" },
+    }),
+  );
+  state = applyEvent(
+    state,
+    ev({ seq: 7, type: "run.completed", payload: { status: "completed", stop_reason: "completed" } }),
+  );
+  assistant = state.items.find((item) => item.kind === "assistant");
+  assert.ok(assistant && assistant.kind === "assistant");
+  assert.equal(assistant.reasoning, "think first");
+  assert.equal(assistant.text, "pong");
+  assert.equal(assistant.streaming, false);
+});
+
 test("tool and approval lifecycle", () => {
   let state = emptyState();
   state = applyEvent(
@@ -617,6 +663,7 @@ test("decodeText and parseDelta accept backend payloads", () => {
   assert.equal(decodeText('{"text":"hi"}'), "hi");
   assert.equal(decodeText('{"text":""}'), "");
   assert.deepEqual(parseDelta({ text: "x" }), { kind: "text", text: "x" });
+  assert.deepEqual(parseDelta({ reasoning: "why" }), { kind: "reasoning", text: "why" });
   assert.equal(parseDelta({ id: "c1", name: "ping" }).kind, "tool");
 });
 

packages/core/chat/reducer.ts

@@ -213,17 +213,20 @@ function applyRunStateChanged(state: SessionState, event: AgentEvent): SessionSt
   return next;
 }
 
+// applyAssistantStarted 占一条流式助手气泡，正文和思考都先空着。
 function applyAssistantStarted(state: SessionState, event: AgentEvent): SessionState {
   const payload = event.payload as AssistantStartedPayload;
   return upsertAssistant(state, {
     runId: event.run_id,
     messageId: payload.message_id,
     text: "",
+    reasoning: "",
     streaming: true,
     seq: event.seq,
   });
 }
 
+// applyAssistantDelta 拼接正文或思考片段；任一到达就撤掉状态字 Thinking。
 function applyAssistantDelta(state: SessionState, event: AgentEvent): SessionState {
   const payload = event.payload as AssistantDeltaPayload;
   const parsed = parseDelta(payload.delta);
@@ -242,6 +245,21 @@ function applyAssistantDelta(state: SessionState, event: AgentEvent): SessionSta
     }
     return next;
   }
+  if (parsed.kind === "reasoning") {
+    const existing = findAssistant(state, payload.message_id);
+    const reasoning = (existing?.reasoning ?? "") + parsed.text;
+    let next = upsertAssistant(state, {
+      runId: event.run_id,
+      messageId: payload.message_id,
+      reasoning,
+      streaming: true,
+      seq: event.seq,
+    });
+    if (reasoning) {
+      next = removeItem(next, thinkingId(event.run_id));
+    }
+    return next;
+  }
   if (parsed.kind === "tool") {
     return upsertTool(state, {
       runId: event.run_id,
@@ -253,12 +271,14 @@ function applyAssistantDelta(state: SessionState, event: AgentEvent): SessionSta
   return state;
 }
 
+// applyAssistantCompleted 收齐本轮正文、思考和待执行工具，并结束流式。
 function applyAssistantCompleted(state: SessionState, event: AgentEvent): SessionState {
   const payload = event.payload as AssistantCompletedPayload;
   let next = upsertAssistant(state, {
     runId: event.run_id,
     messageId: payload.message_id,
     text: decodeText(payload.text),
+    reasoning: payload.reasoning,
     streaming: false,
     seq: event.seq,
   });
@@ -559,16 +579,26 @@ function upsertThinking(
   });
 }
 
+// upsertAssistant 更新同一条助手消息；未传入的正文或思考沿用已有值。
 function upsertAssistant(
   state: SessionState,
-  input: { runId: string; messageId: string; text: string; streaming: boolean; seq: number },
+  input: {
+    runId: string;
+    messageId: string;
+    text?: string;
+    reasoning?: string;
+    streaming: boolean;
+    seq: number;
+  },
 ): SessionState {
+  const existing = findAssistant(state, input.messageId);
   return upsertItem(state, {
     kind: "assistant",
     id: assistantId(input.messageId),
     runId: input.runId,
     messageId: input.messageId,
-    text: input.text,
+    text: input.text ?? existing?.text ?? "",
+    reasoning: input.reasoning ?? existing?.reasoning,
     streaming: input.streaming,
     seq: input.seq,
   });

packages/core/chat/types.ts

@@ -180,6 +180,7 @@ export interface AssistantDeltaPayload {
 export interface AssistantCompletedPayload {
   message_id: string;
   text: string;
+  reasoning?: string;
   tool_calls?: ToolCall[];
 }
 
@@ -319,6 +320,7 @@ export type TimelineItem =
       runId: string;
       messageId: string;
       text: string;
+      reasoning?: string;
       streaming: boolean;
       seq: number;
     }

packages/ui/components/message.tsx

@@ -37,20 +37,22 @@ export function Message({
   );
 }
 
+// MessageContent 包住一条消息的正文，行高是字号的 1.5 倍。
 export function MessageContent({ className, ...props }: HTMLAttributes<HTMLDivElement>) {
-  return <div className={cn("text-sm leading-5", className)} {...props} />;
+  return <div className={cn("text-sm leading-[1.6]", className)} {...props} />;
 }
 
 const plugins = { cjk, code, math, mermaid };
 
 export type MessageResponseProps = ComponentProps<typeof Streamdown>;
 
+// MessageResponse 渲染助手的 Markdown 正文，行高与消息正文一致。
 export const MessageResponse = memo(
   function MessageResponse({ className, plugins: extra, ...props }: MessageResponseProps) {
     return (
       <Streamdown
         className={cn(
-          "size-full space-y-1 leading-5 [&>*:first-child]:mt-0 [&>*:last-child]:mb-0",
+          "size-full space-y-1 leading-[1.6] [&>*:first-child]:mt-0 [&>*:last-child]:mb-0",
           "[&_[data-streamdown^='heading']]:mt-2.5 [&_[data-streamdown^='heading']]:mb-1",
           "[&_li]:py-0",
           "[&_a]:underline [&_blockquote]:border-l-2 [&_blockquote]:border-border [&_blockquote]:pl-3 [&_blockquote]:text-muted-foreground",

packages/ui/components/reasoning.tsx

@@ -6,6 +6,7 @@ import {
   useContext,
   useEffect,
   useMemo,
+  useRef,
   useState,
   type ReactNode,
 } from "react";
@@ -25,6 +26,7 @@ type ReasoningContextValue = {
 
 const ReasoningContext = createContext<ReasoningContextValue | null>(null);
 
+// Reasoning 折叠模型思考。流式时展开，这一段结束后收回，避免和正文叠在一起。
 export function Reasoning({
   className,
   isStreaming = false,
@@ -37,11 +39,15 @@ export function Reasoning({
   children: ReactNode;
 }) {
   const [open, setOpen] = useState(defaultOpen ?? isStreaming);
+  const wasStreaming = useRef(isStreaming);
 
   useEffect(() => {
     if (isStreaming) {
       setOpen(true);
+    } else if (wasStreaming.current) {
+      setOpen(false);
     }
+    wasStreaming.current = isStreaming;
   }, [isStreaming]);
 
   const value = useMemo(() => ({ isStreaming, isOpen: open }), [isStreaming, open]);
@@ -59,6 +65,7 @@ export function Reasoning({
   );
 }
 
+// ReasoningTrigger 是思考折叠的标题，流式时显示 Thinking。
 export function ReasoningTrigger({
   children,
   className,
@@ -89,6 +96,7 @@ export function ReasoningTrigger({
   );
 }
 
+// ReasoningContent 在展开后渲染思考正文。
 export function ReasoningContent({
   className,
   children,