diff --git a/src/config.ts b/src/config.ts
index 23af3be..30a4022 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -65,6 +65,8 @@ const envSchema = z
     SESSION_HISTORY_STORAGE_DIR: z.string().default("./data/session-history"),
     // conversation metadata 持久化目录。
     CONVERSATION_STORAGE_DIR: z.string().default("./data/conversations"),
+    // conversation UI state 持久化目录。
+    CONVERSATION_STATE_STORAGE_DIR: z.string().default("./data/conversation-states"),
     // 每个会话最多保留多少轮 transcript，超过后裁剪旧记录。
     SESSION_HISTORY_MAX_TURNS_PER_SESSION: z.coerce
       .number()
diff --git a/src/conversations/stateStore.ts b/src/conversations/stateStore.ts
new file mode 100644
index 0000000..fddaf83
--- /dev/null
+++ b/src/conversations/stateStore.ts
@@ -0,0 +1,41 @@
+import { join } from "node:path";
+
+import { config } from "../config.js";
+import {
+  atomicWriteJson,
+  ensureDirectory,
+  readJsonFile,
+  removeFileIfExists,
+} from "../utils/fileStore.js";
+
+export type ConversationStateRecord = {
+  sessionId: string;
+  isTitleManuallyEdited?: boolean;
+  messages: unknown[];
+  branchGroups: unknown[];
+};
+
+export class ConversationStateStore {
+  constructor(private readonly baseDir = config.CONVERSATION_STATE_STORAGE_DIR) {}
+
+  async initialize() {
+    await ensureDirectory(this.baseDir);
+  }
+
+  async read(sessionScopeKey: string) {
+    return await readJsonFile<ConversationStateRecord>(this.filePath(sessionScopeKey));
+  }
+
+  async write(sessionScopeKey: string, state: ConversationStateRecord) {
+    await atomicWriteJson(this.filePath(sessionScopeKey), state);
+    return state;
+  }
+
+  async remove(sessionScopeKey: string) {
+    await removeFileIfExists(this.filePath(sessionScopeKey));
+  }
+
+  private filePath(sessionScopeKey: string) {
+    return join(this.baseDir, `${sessionScopeKey}.json`);
+  }
+}
diff --git a/src/conversations/store.ts b/src/conversations/store.ts
index f7ec26b..2e5f3c8 100644
--- a/src/conversations/store.ts
+++ b/src/conversations/store.ts
@@ -2,7 +2,13 @@ import { randomUUID } from "node:crypto";
 import { join } from "node:path";
 
 import { config } from "../config.js";
-import { atomicWriteJson, ensureDirectory, readJsonFile } from "../utils/fileStore.js";
+import {
+  atomicWriteJson,
+  ensureDirectory,
+  listJsonFiles,
+  readJsonFile,
+  removeFileIfExists,
+} from "../utils/fileStore.js";
 import { toConversationScopeKey } from "../utils/fileStore.js";
 
 export type ConversationStatus = "active" | "archived";
@@ -81,7 +87,10 @@ export class ConversationStore {
     );
   }
 
-  async touch(record: ConversationRecord, updates: Partial<Pick<ConversationRecord, "title" | "status">> = {}) {
+  async touch(
+    record: ConversationRecord,
+    updates: Partial<Pick<ConversationRecord, "title" | "status">> = {},
+  ) {
     const next: ConversationRecord = {
       ...record,
       ...normalizeConversationUpdates(updates),
@@ -91,6 +100,25 @@ export class ConversationStore {
     return next;
   }
 
+  async list(context: ConversationContext) {
+    const files = await listJsonFiles(this.baseDir);
+    const records = await Promise.all(
+      files.map((file) => readJsonFile<ConversationRecord>(file)),
+    );
+    return records
+      .filter((record): record is ConversationRecord => Boolean(record))
+      .filter(
+        (record) =>
+          record.actorKey === context.actorKey &&
+          record.projectKey === context.projectKey,
+      )
+      .sort((left, right) => right.updatedAt.localeCompare(left.updatedAt));
+  }
+
+  async remove(record: ConversationRecord) {
+    await removeFileIfExists(this.filePath(record.sessionScopeKey));
+  }
+
   private filePath(sessionScopeKey: string) {
     return join(this.baseDir, `${sessionScopeKey}.json`);
   }
@@ -113,7 +141,7 @@ const normalizeConversationUpdates = (
   if (typeof updates.title === "string") {
     const trimmed = updates.title.trim();
     if (trimmed) {
-      normalized.title = trimmed;
+      normalized.title = trimmed.slice(0, 120);
     }
   }
   return normalized;
diff --git a/src/routes/chat.ts b/src/routes/chat.ts
index 9f568cf..d3f0e51 100644
--- a/src/routes/chat.ts
+++ b/src/routes/chat.ts
@@ -5,6 +5,7 @@ import { type LearningOrchestrator } from "../learning/orchestrator.js";
 import { type SessionHistoryStore } from "../history/store.js";
 import { logger } from "../logger.js";
 import { MemoryStore } from "../memory/store.js";
+import { type ConversationStateStore } from "../conversations/stateStore.js";
 import { type ConversationStore } from "../conversations/store.js";
 import { type ResultReferenceResolver } from "../results/resolver.js";
 import { RESULT_REFERENCE_KIND } from "../results/store.js";
@@ -14,6 +15,7 @@ import { toActorKey, toProjectKey } from "../utils/fileStore.js";
 import {
   buildPromptWithLearningContext,
   generateSessionTitle,
+  shouldGenerateSessionTitle,
 } from "./chatSession.js";
 import {
   collectTextContent,
@@ -42,10 +44,18 @@ const forkPayloadSchema = z.object({
   keep_message_count: z.coerce.number().int().min(0),
 });
 
+const conversationStateSchema = z.object({
+  title: z.string().max(120).optional(),
+  is_title_manually_edited: z.boolean().optional(),
+  messages: z.array(z.unknown()).default([]),
+  branch_groups: z.array(z.unknown()).default([]),
+});
+
 export const buildChatRouter = (
   sessionBridge: ChatSessionBridge,
   runtime: OpencodeRuntimeAdapter,
   conversationStore: ConversationStore,
+  conversationStateStore: ConversationStateStore,
   memoryStore: MemoryStore,
   sessionHistoryStore: SessionHistoryStore,
   learningOrchestrator: LearningOrchestrator,
@@ -87,6 +97,178 @@ export const buildChatRouter = (
     });
   });
 
+  chatRouter.get("/sessions", async (req, res) => {
+    const projectId = req.header("x-project-id") ?? undefined;
+    const userId = req.header("x-user-id") ?? undefined;
+    const actorKey = toActorKey(userId);
+    const projectKey = toProjectKey(projectId);
+    const records = await conversationStore.list({
+      actorKey,
+      projectId,
+      projectKey,
+      userId,
+    });
+    res.json({
+      sessions: records.map((record) => ({
+        id: record.sessionId,
+        title: record.title ?? "新对话",
+        created_at: record.createdAt,
+        updated_at: record.updatedAt,
+        status: record.status,
+        parent_session_id: record.parentSessionId,
+      })),
+    });
+  });
+
+  chatRouter.get("/session/:sessionId", async (req, res) => {
+    const sessionId = req.params.sessionId?.trim();
+    const projectId = req.header("x-project-id") ?? undefined;
+    const userId = req.header("x-user-id") ?? undefined;
+    const actorKey = toActorKey(userId);
+    const projectKey = toProjectKey(projectId);
+    if (!sessionId) {
+      res.status(400).json({ message: "session_id is required" });
+      return;
+    }
+
+    const conversation = await conversationStore.get(
+      {
+        actorKey,
+        projectId,
+        projectKey,
+        userId,
+      },
+      sessionId,
+    );
+    if (!conversation) {
+      res.status(404).json({ message: "session not found" });
+      return;
+    }
+
+    const state = await conversationStateStore.read(conversation.sessionScopeKey);
+    res.json({
+      id: conversation.sessionId,
+      title: conversation.title ?? "新对话",
+      is_title_manually_edited: state?.isTitleManuallyEdited ?? false,
+      created_at: conversation.createdAt,
+      updated_at: conversation.updatedAt,
+      status: conversation.status,
+      session_id: conversation.sessionId,
+      messages: state?.messages ?? [],
+      branch_groups: state?.branchGroups ?? [],
+      parent_session_id: conversation.parentSessionId,
+    });
+  });
+
+  chatRouter.put("/session/:sessionId", async (req, res) => {
+    const sessionId = req.params.sessionId?.trim();
+    const parsed = conversationStateSchema.safeParse(req.body ?? {});
+    if (!parsed.success) {
+      res.status(400).json({
+        message: "invalid request payload",
+        detail: parsed.error.flatten(),
+      });
+      return;
+    }
+
+    const projectId = req.header("x-project-id") ?? undefined;
+    const userId = req.header("x-user-id") ?? undefined;
+    const actorKey = toActorKey(userId);
+    const projectKey = toProjectKey(projectId);
+    if (!sessionId) {
+      res.status(400).json({ message: "session_id is required" });
+      return;
+    }
+
+    const { record } = await conversationStore.ensure({
+      actorKey,
+      projectId,
+      projectKey,
+      sessionId,
+      userId,
+    });
+    const nextRecord = await conversationStore.touch(record, {
+      ...(parsed.data.title ? { title: parsed.data.title } : {}),
+    });
+    await conversationStateStore.write(nextRecord.sessionScopeKey, {
+      sessionId: nextRecord.sessionId,
+      isTitleManuallyEdited: parsed.data.is_title_manually_edited,
+      messages: parsed.data.messages,
+      branchGroups: parsed.data.branch_groups,
+    });
+    res.json({
+      id: nextRecord.sessionId,
+      title: nextRecord.title ?? "新对话",
+      created_at: nextRecord.createdAt,
+      updated_at: nextRecord.updatedAt,
+      status: nextRecord.status,
+      session_id: nextRecord.sessionId,
+    });
+  });
+
+  chatRouter.patch("/session/:sessionId/title", async (req, res) => {
+    const sessionId = req.params.sessionId?.trim();
+    const title =
+      typeof req.body?.title === "string" ? req.body.title.trim() : "";
+    const isTitleManuallyEdited =
+      typeof req.body?.is_title_manually_edited === "boolean"
+        ? req.body.is_title_manually_edited
+        : undefined;
+    const projectId = req.header("x-project-id") ?? undefined;
+    const userId = req.header("x-user-id") ?? undefined;
+    const actorKey = toActorKey(userId);
+    const projectKey = toProjectKey(projectId);
+    if (!sessionId || !title) {
+      res.status(400).json({ message: "session_id and title are required" });
+      return;
+    }
+    const conversation = await conversationStore.get(
+      { actorKey, projectId, projectKey, userId },
+      sessionId,
+    );
+    if (!conversation) {
+      res.status(404).json({ message: "session not found" });
+      return;
+    }
+    const nextConversation = await conversationStore.touch(conversation, { title });
+    const state = await conversationStateStore.read(nextConversation.sessionScopeKey);
+    if (state) {
+      await conversationStateStore.write(nextConversation.sessionScopeKey, {
+        ...state,
+        isTitleManuallyEdited:
+          isTitleManuallyEdited ?? state.isTitleManuallyEdited,
+      });
+    }
+    res.json({
+      id: nextConversation.sessionId,
+      title: nextConversation.title,
+      updated_at: nextConversation.updatedAt,
+    });
+  });
+
+  chatRouter.delete("/session/:sessionId", async (req, res) => {
+    const sessionId = req.params.sessionId?.trim();
+    const projectId = req.header("x-project-id") ?? undefined;
+    const userId = req.header("x-user-id") ?? undefined;
+    const actorKey = toActorKey(userId);
+    const projectKey = toProjectKey(projectId);
+    if (!sessionId) {
+      res.status(400).json({ message: "session_id is required" });
+      return;
+    }
+    const conversation = await conversationStore.get(
+      { actorKey, projectId, projectKey, userId },
+      sessionId,
+    );
+    if (!conversation) {
+      res.status(204).end();
+      return;
+    }
+    await conversationStateStore.remove(conversation.sessionScopeKey);
+    await conversationStore.remove(conversation);
+    res.status(204).end();
+  });
+
   chatRouter.get("/render-ref/:renderRef", async (req, res) => {
     const renderRef = req.params.renderRef?.trim();
     const userId = req.header("x-user-id")?.trim();
@@ -364,9 +546,21 @@ export const buildChatRouter = (
             .reverse()
             .find((message) => message.info.role === "assistant");
           const assistantText = collectTextContent(assistantMessage?.parts ?? []);
-          const existingSessionTitle = activeConversation.title;
+          const latestConversation =
+            (await conversationStore.get(
+              { actorKey, projectId, projectKey, userId },
+              activeConversation.sessionId,
+            )) ?? activeConversation;
+          const latestConversationState = await conversationStateStore.read(
+            latestConversation.sessionScopeKey,
+          );
+          const existingSessionTitle = latestConversation.title;
           let sessionTitle = existingSessionTitle;
-          const shouldGenerateTitle = recentTurns.length <= 1;
+          const shouldGenerateTitle = shouldGenerateSessionTitle({
+            recentTurnCount: recentTurns.length,
+            isTitleManuallyEdited:
+              latestConversationState?.isTitleManuallyEdited ?? false,
+          });
           if (shouldGenerateTitle) {
             sessionTitle = await generateSessionTitle(runtime, {
               sessionId: binding.sessionId,
@@ -374,7 +568,7 @@ export const buildChatRouter = (
               fallbackTitle: existingSessionTitle,
             });
           }
-          const nextConversation = await conversationStore.touch(activeConversation, {
+          const nextConversation = await conversationStore.touch(latestConversation, {
             ...(sessionTitle && sessionTitle !== existingSessionTitle
               ? { title: sessionTitle }
               : {}),
diff --git a/src/routes/chatSession.ts b/src/routes/chatSession.ts
index 9bc3758..f3102bd 100644
--- a/src/routes/chatSession.ts
+++ b/src/routes/chatSession.ts
@@ -75,6 +75,11 @@ const normalizeGeneratedTitle = (rawTitle: string, fallback: string) => {
   return normalized.length > 24 ? `${normalized.slice(0, 24)}...` : normalized;
 };
 
+export const shouldGenerateSessionTitle = (options: {
+  recentTurnCount: number;
+  isTitleManuallyEdited: boolean;
+}) => options.recentTurnCount <= 1 && !options.isTitleManuallyEdited;
+
 export const generateSessionTitle = async (
   runtime: OpencodeRuntimeAdapter,
   options: {
diff --git a/src/server.ts b/src/server.ts
index d56080a..24bcc46 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -5,6 +5,7 @@ import express from "express";
 import { SessionHistoryStore } from "./history/store.js";
 import { ChatSessionBridge } from "./chat/sessionBridge.js";
 import { config } from "./config.js";
+import { ConversationStateStore } from "./conversations/stateStore.js";
 import { ConversationStore } from "./conversations/store.js";
 import { logger } from "./logger.js";
 import { LearningOrchestrator } from "./learning/orchestrator.js";
@@ -19,6 +20,7 @@ import { DynamicHttpExecutor } from "./tools/dynamicHttpExecutor.js";
 const app = express();
 const sessionBridge = new ChatSessionBridge(opencodeRuntime);
 const conversationStore = new ConversationStore();
+const conversationStateStore = new ConversationStateStore();
 const memoryStore = new MemoryStore();
 const sessionHistoryStore = new SessionHistoryStore();
 const toolContextStore = new ToolSessionContextStore();
@@ -246,6 +248,7 @@ app.use(
     sessionBridge,
     opencodeRuntime,
     conversationStore,
+    conversationStateStore,
     memoryStore,
     sessionHistoryStore,
     learningOrchestrator,
@@ -256,6 +259,7 @@ app.use(
 const bootstrap = async () => {
   await Promise.all([
     conversationStore.initialize(),
+    conversationStateStore.initialize(),
     learningOrchestrator.initialize(),
     memoryStore.initialize(),
     resultReferenceStore.initialize(),
diff --git a/tests/routes/chatSession.test.ts b/tests/routes/chatSession.test.ts
new file mode 100644
index 0000000..cad6ea2
--- /dev/null
+++ b/tests/routes/chatSession.test.ts
@@ -0,0 +1,38 @@
+import { describe, expect, it } from "bun:test";
+
+import { shouldGenerateSessionTitle } from "../../src/routes/chatSession.js";
+
+describe("shouldGenerateSessionTitle", () => {
+  it("allows auto-title generation for the first turn when the title was not edited", () => {
+    expect(
+      shouldGenerateSessionTitle({
+        recentTurnCount: 0,
+        isTitleManuallyEdited: false,
+      }),
+    ).toBe(true);
+  });
+
+  it("blocks auto-title generation after the user edits the title manually", () => {
+    expect(
+      shouldGenerateSessionTitle({
+        recentTurnCount: 0,
+        isTitleManuallyEdited: true,
+      }),
+    ).toBe(false);
+  });
+
+  it("only allows auto-title generation during the first two turns", () => {
+    expect(
+      shouldGenerateSessionTitle({
+        recentTurnCount: 1,
+        isTitleManuallyEdited: false,
+      }),
+    ).toBe(true);
+    expect(
+      shouldGenerateSessionTitle({
+        recentTurnCount: 2,
+        isTitleManuallyEdited: false,
+      }),
+    ).toBe(false);
+  });
+});