Preserve chat history after summarization

backend/packages/harness/deerflow/agents/middlewares/summarization_middleware.py

@@ -139,14 +139,15 @@ def _maybe_summarize(self, state: AgentState, runtime: Runtime) -> dict | None:
         messages_to_summarize, preserved_messages = self._preserve_dynamic_context_reminders(messages_to_summarize, preserved_messages)
         self._fire_hooks(messages_to_summarize, preserved_messages, runtime)
         summary = self._create_summary(messages_to_summarize)
-        new_messages = self._build_new_messages(summary)
+        new_messages = self._build_hidden_summary_messages(summary)
 
         return {
             "messages": [
                 RemoveMessage(id=REMOVE_ALL_MESSAGES),
                 *new_messages,
                 *preserved_messages,
-            ]
+            ],
+            "display_messages": self._visible_messages(messages_to_summarize),
         }
 
     async def _amaybe_summarize(self, state: AgentState, runtime: Runtime) -> dict | None:
@@ -165,16 +166,30 @@ async def _amaybe_summarize(self, state: AgentState, runtime: Runtime) -> dict |
         messages_to_summarize, preserved_messages = self._preserve_dynamic_context_reminders(messages_to_summarize, preserved_messages)
         self._fire_hooks(messages_to_summarize, preserved_messages, runtime)
         summary = await self._acreate_summary(messages_to_summarize)
-        new_messages = self._build_new_messages(summary)
+        new_messages = self._build_hidden_summary_messages(summary)
 
         return {
             "messages": [
                 RemoveMessage(id=REMOVE_ALL_MESSAGES),
                 *new_messages,
                 *preserved_messages,
-            ]
+            ],
+            "display_messages": self._visible_messages(messages_to_summarize),
         }
 
+    def _build_hidden_summary_messages(self, summary: str) -> list[AnyMessage]:
+        new_messages = self._build_new_messages(summary)
+        for message in new_messages:
+            message.additional_kwargs = {
+                **getattr(message, "additional_kwargs", {}),
+                "hide_from_ui": True,
+            }
+        return new_messages
+
+    @staticmethod
+    def _visible_messages(messages: list[AnyMessage]) -> list[AnyMessage]:
+        return [message for message in messages if getattr(message, "additional_kwargs", {}).get("hide_from_ui") is not True]
+
     @override
     def _build_new_messages(self, summary: str) -> list[HumanMessage]:
         """Override the base implementation to let the human message with the special name 'summary'.

backend/packages/harness/deerflow/agents/thread_state.py

@@ -1,6 +1,7 @@
 from typing import Annotated, NotRequired, TypedDict
 
 from langchain.agents import AgentState
+from langchain_core.messages import AnyMessage
 
 
 class SandboxState(TypedDict):
@@ -45,11 +46,31 @@ def merge_viewed_images(existing: dict[str, ViewedImageData] | None, new: dict[s
     return {**existing, **new}
 
 
+def merge_display_messages(existing: list[AnyMessage] | None, new: list[AnyMessage] | None) -> list[AnyMessage]:
+    """Reducer for UI-only messages archived before model-context summarization."""
+    if existing is None:
+        existing = []
+    if new is None:
+        return existing
+
+    merged: list[AnyMessage] = []
+    seen_ids: set[str] = set()
+    for message in [*existing, *new]:
+        message_id = getattr(message, "id", None)
+        if message_id:
+            if message_id in seen_ids:
+                continue
+            seen_ids.add(message_id)
+        merged.append(message)
+    return merged
+
+
 class ThreadState(AgentState):
     sandbox: NotRequired[SandboxState | None]
     thread_data: NotRequired[ThreadDataState | None]
     title: NotRequired[str | None]
     artifacts: Annotated[list[str], merge_artifacts]
+    display_messages: Annotated[list[AnyMessage], merge_display_messages]
     todos: NotRequired[list | None]
     uploaded_files: NotRequired[list[dict] | None]
     viewed_images: Annotated[dict[str, ViewedImageData], merge_viewed_images]  # image_path -> {base64, mime_type}

backend/tests/test_summarization_middleware.py

@@ -112,6 +112,8 @@ def test_before_summarization_hook_receives_messages_before_compression() -> Non
     assert captured[0].agent_name is None
     assert isinstance(result["messages"][0], RemoveMessage)
     assert result["messages"][1].content.startswith("Here is a summary")
+    assert result["messages"][1].additional_kwargs["hide_from_ui"] is True
+    assert [message.content for message in result["display_messages"]] == ["user-1", "assistant-1"]
 
 
 def test_dynamic_context_reminder_is_preserved_across_summarization() -> None:
@@ -193,6 +195,19 @@ async def test_abefore_model_calls_hooks_same_as_sync() -> None:
     assert [message.content for message in captured[0].messages_to_summarize] == ["user-1", "assistant-1"]
 
 
+@pytest.mark.anyio
+async def test_abefore_model_returns_visible_history_after_summarization() -> None:
+    middleware = _middleware()
+
+    result = await middleware.abefore_model({"messages": _messages()}, _runtime())
+
+    assert isinstance(result["messages"][0], RemoveMessage)
+    assert result["messages"][1].content.startswith("Here is a summary")
+    assert result["messages"][1].additional_kwargs["hide_from_ui"] is True
+    assert [message.content for message in result["display_messages"]] == ["user-1", "assistant-1"]
+    assert [message.content for message in result["messages"][2:]] == ["user-2", "assistant-2"]
+
+
 def test_memory_flush_hook_skips_when_memory_disabled(monkeypatch: pytest.MonkeyPatch) -> None:
     queue = MagicMock()
     monkeypatch.setattr("deerflow.agents.memory.summarization_hook.get_memory_config", lambda: MemoryConfig(enabled=False))

frontend/src/components/workspace/messages/message-list.tsx

@@ -175,7 +175,10 @@ export function MessageList({
   const { t } = useI18n();
   const rehypePlugins = useRehypeSplitWordsIntoSpans(thread.isLoading);
   const updateSubtask = useUpdateSubtask();
-  const messages = thread.messages;
+  const messages = useMemo(
+    () => [...(thread.values.display_messages ?? []), ...thread.messages],
+    [thread.messages, thread.values.display_messages],
+  );
   const groupedMessages = getMessageGroups(messages);
   const turnUsageMessagesByGroupIndex =
     getAssistantTurnUsageMessages(groupedMessages);

frontend/src/core/threads/types.ts

@@ -5,6 +5,7 @@ import type { Todo } from "../todos";
 export interface AgentThreadState extends Record<string, unknown> {
   title: string;
   messages: Message[];
+  display_messages?: Message[];
   artifacts: string[];
   todos?: Todo[];
 }

frontend/tests/e2e/chat.spec.ts

@@ -1,6 +1,10 @@
 import { expect, test } from "@playwright/test";
 
-import { handleRunStream, mockLangGraphAPI } from "./utils/mock-api";
+import {
+  handleRunStream,
+  MOCK_THREAD_ID_2,
+  mockLangGraphAPI,
+} from "./utils/mock-api";
 
 test.describe("Chat workspace", () => {
   test.beforeEach(async ({ page }) => {
@@ -49,6 +53,68 @@ test.describe("Chat workspace", () => {
     });
   });
 
+  test("shows archived messages after summarization without showing the summary", async ({
+    page,
+  }) => {
+    await page.unrouteAll({ behavior: "ignoreErrors" });
+    mockLangGraphAPI(page, {
+      threads: [
+        {
+          thread_id: MOCK_THREAD_ID_2,
+          title: "LLM Wiki Report Outline",
+          values: {
+            display_messages: [
+              {
+                type: "human",
+                id: "archived-human-1",
+                content: [
+                  {
+                    type: "text",
+                    text: "Generate a McKinsey-grade research report on LLM Wiki.",
+                  },
+                ],
+              },
+              {
+                type: "ai",
+                id: "archived-ai-1",
+                content: "I will gather sources and build the report outline.",
+              },
+            ],
+            messages: [
+              {
+                type: "human",
+                id: "summary-hidden",
+                content:
+                  "Here is a summary of the conversation to date:\n\nCore Task...",
+                additional_kwargs: { hide_from_ui: true },
+              },
+              {
+                type: "ai",
+                id: "current-ai-1",
+                content: "Continuing with the final report section.",
+              },
+            ],
+          },
+        },
+      ],
+    });
+
+    await page.goto(`/workspace/chats/${MOCK_THREAD_ID_2}`);
+
+    await expect(
+      page.getByText("Generate a McKinsey-grade research report on LLM Wiki."),
+    ).toBeVisible({ timeout: 15_000 });
+    await expect(
+      page.getByText("I will gather sources and build the report outline."),
+    ).toBeVisible();
+    await expect(
+      page.getByText("Continuing with the final report section."),
+    ).toBeVisible();
+    await expect(
+      page.getByText("Here is a summary of the conversation to date"),
+    ).toHaveCount(0);
+  });
+
   test("keeps attachments visible while upload submit is pending", async ({
     page,
   }) => {

frontend/tests/e2e/utils/mock-api.ts

@@ -6,6 +6,7 @@
  * `handleRunStream` from here.
  */
 
+import type { Message } from "@langchain/langgraph-sdk";
 import type { Page, Route } from "@playwright/test";
 
 // ---------------------------------------------------------------------------
@@ -25,6 +26,11 @@ export type MockThread = {
   title?: string;
   updated_at?: string;
   agent_name?: string;
+  values?: {
+    title?: string;
+    messages?: Message[];
+    display_messages?: Message[];
+  };
 };
 
 export type MockAgent = {
@@ -59,7 +65,7 @@ export function mockLangGraphAPI(page: Page, options?: MockAPIOptions) {
       updated_at: t.updated_at ?? "2025-01-01T00:00:00Z",
       metadata: t.agent_name ? { agent_name: t.agent_name } : {},
       status: "idle",
-      values: { title: t.title ?? "Untitled" },
+      values: { title: t.title ?? t.values?.title ?? "Untitled" },
     }));
     return route.fulfill({
       status: 200,
@@ -112,8 +118,12 @@ export function mockLangGraphAPI(page: Page, options?: MockAPIOptions) {
         body: JSON.stringify([
           {
             values: {
-              title: matchingThread.title ?? "Untitled",
-              messages: [
+              title:
+                matchingThread.title ??
+                matchingThread.values?.title ??
+                "Untitled",
+              display_messages: matchingThread.values?.display_messages,
+              messages: matchingThread.values?.messages ?? [
                 {
                   type: "human",
                   id: `msg-human-${matchingThread.thread_id}`,
@@ -122,7 +132,9 @@ export function mockLangGraphAPI(page: Page, options?: MockAPIOptions) {
                 {
                   type: "ai",
                   id: `msg-ai-${matchingThread.thread_id}`,
-                  content: `Response in thread ${matchingThread.title ?? matchingThread.thread_id}`,
+                  content: `Response in thread ${
+                    matchingThread.title ?? matchingThread.thread_id
+                  }`,
                 },
               ],
             },
@@ -153,9 +165,13 @@ export function mockLangGraphAPI(page: Page, options?: MockAPIOptions) {
         contentType: "application/json",
         body: JSON.stringify({
           values: {
-            title: matchingThread?.title ?? "Untitled",
+            title:
+              matchingThread?.title ??
+              matchingThread?.values?.title ??
+              "Untitled",
+            display_messages: matchingThread?.values?.display_messages,
             messages: matchingThread
-              ? [
+              ? (matchingThread.values?.messages ?? [
                   {
                     type: "human",
                     id: `msg-human-${matchingThread.thread_id}`,
@@ -164,9 +180,11 @@ export function mockLangGraphAPI(page: Page, options?: MockAPIOptions) {
                   {
                     type: "ai",
                     id: `msg-ai-${matchingThread.thread_id}`,
-                    content: `Response in thread ${matchingThread.title ?? matchingThread.thread_id}`,
+                    content: `Response in thread ${
+                      matchingThread.title ?? matchingThread.thread_id
+                    }`,
                   },
-                ]
+                ])
               : [],
           },
           next: [],