fix(ui): stabilize assistant message accumulation

kagent-ui/CHANGELOG.md

@@ -1,5 +1,16 @@
 # CHANGELOG
 
+## 2026-04-16
+
+- 修复聊天界面 assistant 回复重复显示：
+  - 为 assistant UI 消息补充 `turnId` 元信息，并在前端状态层归并同一 turn 中相邻的 assistant 气泡，避免 `item/started`、`item/agentMessage/delta`、`item/completed` 之间的消息 ID 不一致时留下重复回复。
+  - `thread/resume` 历史恢复沿用同样的相邻 assistant 归并规则，避免切换或重开线程后再次出现重复欢迎语。
+  - 新增 `messages.test.ts` 回归测试，覆盖相邻 assistant 合并、chunked assistant 片段重组、live delta 归并与历史恢复路径，并确保中间夹有其他 item 时不会误合并。
+- 修复聊天界面 SSE 增量消息累积问题：
+  - `use-codex-session` 改为为 `reasoning` 与 `mcpToolCall/progress` 使用按 turn 稳定的临时消息 ID，流式增量改为原地更新，不再为每个增量块堆出新的消息条目。
+  - `turn/completed` 与 `error` 事件现在会清理当前 turn 的临时思考/工具进度卡片，避免对话结束后残留重复占位消息。
+  - 新增 `messages.test.ts`，覆盖临时消息清理与流式占位原地更新的纯函数行为。
+
 ## 2026-02-24
 
 - 修复“查看沙箱日志”鉴权失败（401）：

kagent-ui/components/assistant-ui/thread.tsx

@@ -14,7 +14,11 @@ import {
 import ReactMarkdown from "react-markdown";
 import remarkGfm from "remark-gfm";
 import { Button } from "@/components/ui/button";
-import { getProviderTypeMeta, PROVIDER_TYPE_ICON_MAP } from "@/lib/model-provider-type";
+import type { FileUpdateChange } from "@/lib/codex-app-server/v2/FileUpdateChange";
+import {
+  getProviderTypeMeta,
+  PROVIDER_TYPE_ICON_MAP,
+} from "@/lib/model-provider-type";
 import {
   Select,
   SelectContent,
@@ -28,7 +32,7 @@ export type UserAttachment = { type: "image" | "localImage"; src: string };
 
 export type UiMessage =
   | { id: string; kind: "user"; text: string; attachments: UserAttachment[] }
-  | { id: string; kind: "assistant"; text: string }
+  | { id: string; kind: "assistant"; text: string; turnId?: string }
   | { id: string; kind: "turnCompleted"; turnId: string; text: string }
   | { id: string; kind: "reasoning"; summary: string[]; content: string[] }
   | {
@@ -45,7 +49,7 @@ export type UiMessage =
       id: string;
       kind: "fileChange";
       status: string;
-      changes: Array<{ path: string; kind: string; diff: string }>;
+      changes: Array<FileUpdateChange>;
       output: string | null;
     }
   | {
@@ -469,7 +473,7 @@ function renderAssistantPayload(msg: Exclude<UiMessage, { kind: "user" }>) {
                 className="rounded-md border bg-background p-2"
               >
                 <div className="text-xs text-muted-foreground">
-                  {change.path} · {change.kind}
+                  {change.path} · {formatFileChangeKind(change.kind)}
                 </div>
                 {change.diff ? (
                   <pre className="mt-2 max-h-80 overflow-auto text-xs">
@@ -646,6 +650,19 @@ function formatDuration(ms: number) {
   return `${minutes}m ${rest.toFixed(0)}s`;
 }
 
+function formatFileChangeKind(kind: FileUpdateChange["kind"]) {
+  switch (kind.type) {
+    case "add":
+      return "add";
+    case "delete":
+      return "delete";
+    case "update":
+      return kind.move_path ? `update -> ${kind.move_path}` : "update";
+  }
+  const exhaustiveCheck: never = kind;
+  return exhaustiveCheck;
+}
+
 const markdownComponents: Components = {
   h1: ({ children }) => (
     <h1 className="mb-4 text-2xl font-bold tracking-tight">{children}</h1>