diff --git a/frontends/desktop/src-tauri/capabilities/default.json b/frontends/desktop/src-tauri/capabilities/default.json
index cf96e341..aa9ad1e2 100644
--- a/frontends/desktop/src-tauri/capabilities/default.json
+++ b/frontends/desktop/src-tauri/capabilities/default.json
@@ -18,6 +18,10 @@
     "allow-start-bridge-with-config",
     "allow-get-config",
     "allow-export-mykey",
+    "allow-pick-directory",
+    "allow-get-ga-source",
+    "allow-set-ga-source",
+    "allow-clear-ga-source",
     "allow-shortcut-should-ask",
     "allow-shortcut-decide"
   ]
diff --git a/frontends/desktop/src-tauri/permissions/bridge-commands.toml b/frontends/desktop/src-tauri/permissions/bridge-commands.toml
index cf78df39..313f49be 100644
--- a/frontends/desktop/src-tauri/permissions/bridge-commands.toml
+++ b/frontends/desktop/src-tauri/permissions/bridge-commands.toml
@@ -18,6 +18,26 @@ identifier = "allow-export-mykey"
 description = "Save mykey.py via native file dialog."
 commands.allow = ["export_mykey"]
 
+[[permission]]
+identifier = "allow-pick-directory"
+description = "Pick a source directory via native folder dialog (import memory)."
+commands.allow = ["pick_directory"]
+
+[[permission]]
+identifier = "allow-get-ga-source"
+description = "Read the user-set external GenericAgent source directory."
+commands.allow = ["get_ga_source"]
+
+[[permission]]
+identifier = "allow-set-ga-source"
+description = "Point the desktop shell at an external GenericAgent source and restart the bridge."
+commands.allow = ["set_ga_source"]
+
+[[permission]]
+identifier = "allow-clear-ga-source"
+description = "Clear the external GA source override and fall back to the bundled runtime."
+commands.allow = ["clear_ga_source"]
+
 [[permission]]
 identifier = "allow-shortcut-should-ask"
 description = "Check whether to show the first-run desktop-shortcut prompt."
diff --git a/frontends/desktop/src-tauri/src/lib.rs b/frontends/desktop/src-tauri/src/lib.rs
index 69ab0e3e..410881cc 100644
--- a/frontends/desktop/src-tauri/src/lib.rs
+++ b/frontends/desktop/src-tauri/src/lib.rs
@@ -330,12 +330,54 @@ fn running_inside_app_bundle() -> bool {
         .unwrap_or(false)
 }
 
+/// User-set external GenericAgent source directory (design A: desktop as a thin shell).
+/// Returns the path only when it is a valid GA checkout (has agentmain.py AND
+/// frontends/desktop_bridge.py). An invalid/missing override returns None so callers fall
+/// back to the bundle's own runtime/app — this is the "本体 moved/deleted" safety net.
+fn valid_ga_source_override() -> Option<String> {
+    let s = read_settings()
+        .get("ga_source_override")
+        .and_then(|v| v.as_str())
+        .unwrap_or("")
+        .trim()
+        .to_string();
+    if s.is_empty() {
+        return None;
+    }
+    let p = PathBuf::from(&s);
+    if p.join("agentmain.py").exists() && p.join("frontends").join("desktop_bridge.py").exists() {
+        Some(p.to_string_lossy().to_string())
+    } else {
+        None
+    }
+}
+
+/// Remove a single key from the settings file (merge_settings can only add/overwrite).
+fn remove_setting(key: &str) {
+    let mut obj = read_settings();
+    obj.remove(key);
+    let val = serde_json::Value::Object(obj);
+    if let Ok(text) = serde_json::to_string_pretty(&val) {
+        let _ = std::fs::write(settings_path(), text);
+    }
+}
+
 /// Read config from settings file, or auto-discover and save.
 /// Self-contained bundles always prefer their own runtime/app over stale user settings,
 /// otherwise an old ~/.ga_desktop_settings.json can silently point the UI at a different checkout.
 pub fn get_or_discover_config() -> (String, String) {
     let path = settings_path();
 
+    // A user-set, still-valid external GA source wins over everything — including the bundle's
+    // own runtime/app. This is what turns the desktop app into a thin shell over a separate 本体.
+    // Uses the bundle python (which has deps installed) to run the external source.
+    if let Some(src) = valid_ga_source_override() {
+        let python = find_python();
+        if !python.is_empty() {
+            return (python, src);
+        }
+    }
+
     if bundle_root().is_some() {
         let python = find_python();
         let project = find_project_dir().unwrap_or_default();
@@ -726,28 +768,103 @@ fn export_mykey(content: String) -> Result<Option<String>, String> {
     }
 }
 
+#[tauri::command]
+fn pick_directory(title: Option<String>) -> Option<String> {
+    let mut dlg = rfd::FileDialog::new();
+    if let Some(t) = title {
+        if !t.is_empty() {
+            dlg = dlg.set_title(&t);
+        }
+    }
+    dlg.pick_folder().map(|p| p.to_string_lossy().into_owned())
+}
+
+/// Stop the current bridge (ours or a stale one) and free :14168 before respawning.
+fn stop_current_bridge() {
+    request_bridge_shutdown();
+    if let Some(mut child) = BRIDGE_PROCESS.lock().unwrap().take() {
+        let _ = child.kill();
+        let _ = child.wait();
+    }
+    let start = Instant::now();
+    while is_bridge_running() && start.elapsed() < Duration::from_secs(6) {
+        thread::sleep(Duration::from_millis(150));
+    }
+    if is_bridge_running() {
+        force_free_bridge_port();
+        let start = Instant::now();
+        while is_bridge_running() && start.elapsed() < Duration::from_secs(5) {
+            thread::sleep(Duration::from_millis(150));
+        }
+    }
+}
+
+/// Restart the bridge with whatever get_or_discover_config() now resolves to, then reload the
+/// webview so it reconnects. Shared by set_ga_source / clear_ga_source.
+fn switch_bridge(app_handle: &tauri::AppHandle) -> Result<String, String> {
+    stop_current_bridge();
+    let (py, project) = get_or_discover_config();
+    if project.is_empty() {
+        return Err("no GenericAgent source resolved".into());
+    }
+    spawn_bridge_process(&py, &project)?;
+    if !wait_for_port(14168, Duration::from_secs(20)) {
+        return Err("bridge did not become ready within 20s".into());
+    }
+    show_bridge_window(app_handle);
+    Ok(project)
+}
+
+#[tauri::command]
+fn get_ga_source() -> String {
+    read_settings()
+        .get("ga_source_override")
+        .and_then(|v| v.as_str())
+        .unwrap_or("")
+        .to_string()
+}
+
+#[tauri::command]
+fn set_ga_source(app_handle: tauri::AppHandle, dir: String) -> Result<String, String> {
+    let p = PathBuf::from(&dir);
+    if !p.join("agentmain.py").exists() {
+        return Err("not a GenericAgent source: agentmain.py not found".into());
+    }
+    if !p.join("frontends").join("desktop_bridge.py").exists() {
+        return Err("frontends/desktop_bridge.py not found in the selected directory".into());
+    }
+    merge_settings(serde_json::json!({ "ga_source_override": dir }));
+    switch_bridge(&app_handle)
+}
+
+#[tauri::command]
+fn clear_ga_source(app_handle: tauri::AppHandle) -> Result<String, String> {
+    remove_setting("ga_source_override");
+    switch_bridge(&app_handle)
+}
+
 #[cfg_attr(mobile, tauri::mobile_entry_point)]
 pub fn run() {
     let args: Vec<String> = std::env::args().collect();
     let no_autostart = args.iter().any(|a| a == "--no-autostart");
     let dev_mode = args.iter().any(|a| a == "--dev");
 
-    let project_dir = find_project_dir().unwrap_or_default();
-    let needs_prepare = needs_first_run_prepare(&project_dir);
+    // Resolve the effective config once (honors a user-set external GA source over the bundle).
+    // Use it for takeover + spawn so identity checks match what we actually launch.
+    let (eff_py, eff_project) = get_or_discover_config();
+    let needs_prepare = needs_first_run_prepare(&eff_project);
 
-    takeover_stale_bridge(&project_dir);
+    takeover_stale_bridge(&eff_project);
 
     let bridge_ok = is_bridge_running();
     let mut spawned_bridge = false;
     // Skip the early spawn when a first-run prepare is required (no venv yet);
     // the setup thread prepares the env first and then starts the bridge.
     if !bridge_ok && !no_autostart && !needs_prepare {
-        // Try to start bridge with saved/discovered config
-        let (py_str, dir_str) = get_or_discover_config();
-        let dir = PathBuf::from(&dir_str);
+        let dir = PathBuf::from(&eff_project);
         let script = dir.join("frontends").join("desktop_bridge.py");
         if script.exists() {
-            let mut cmd = Command::new(&py_str);
+            let mut cmd = Command::new(&eff_py);
             cmd.arg(&script).current_dir(&dir);
             sanitize_bundle_env(&mut cmd);
             #[cfg(windows)]
@@ -767,7 +884,7 @@ pub fn run() {
                 let _ = w.set_focus();
             }
         }))
-        .invoke_handler(tauri::generate_handler![start_bridge_with_config, start_bridge, get_config, export_mykey, shortcut_should_ask, shortcut_decide])
+        .invoke_handler(tauri::generate_handler![start_bridge_with_config, start_bridge, get_config, export_mykey, pick_directory, get_ga_source, set_ga_source, clear_ga_source, shortcut_should_ask, shortcut_decide])
         .setup(move |app| {
             // Show the loading window immediately so the first-run prepare isn't a blank screen.
             // The window starts on loading.html (a local page), so no "connection refused" flash.
@@ -776,7 +893,7 @@ pub fn run() {
             }
 
             let handle = app.handle().clone();
-            let project_dir = project_dir.clone();
+            let project_dir = eff_project.clone();
             thread::spawn(move || {
                 // Progress reporter: push status into the loading window (window.gaProgress).
                 let main_win = handle.get_webview_window("main");
diff --git a/frontends/desktop/static/app.js b/frontends/desktop/static/app.js
index 7ffc842b..d3e1814a 100644
--- a/frontends/desktop/static/app.js
+++ b/frontends/desktop/static/app.js
@@ -284,6 +284,10 @@ let bridgeUiOffline = false;
     getServicePanel: () => rpc('services/panel', {}),
     getMykeyContent: () => rpc('services/mykey/get', {}),
     saveMykeyContent: (content) => rpc('services/mykey/save', { content }),
+    importMemory: (sourceDir) => rpc('memory/import', { sourceDir }),
+    getGaSource: () => tauriInvoke('get_ga_source'),
+    setGaSource: (dir) => tauriInvoke('set_ga_source', { dir }),
+    clearGaSource: () => tauriInvoke('clear_ga_source'),
     getConductorModel: () => rpc('services/conductor/model/get', {}),
     saveConductorModel: (llmNo) => rpc('services/conductor/model/save', { llmNo }),
     tauriInvoke,
@@ -683,6 +687,79 @@ bindClick('export-mykey-btn', async (e) => {
     showChanToast(t('err.mykeyExport'), err.message || String(err), 'err');
   }
 });
+// 记忆/session 导入与外接 GA 源码。
+async function importMemoryFromDir() {
+  let sourceDir = '';
+  if (window.__TAURI__?.core?.invoke) {
+    sourceDir = await window.ga.tauriInvoke('pick_directory', { title: t('sys.memoryPickTitle') });
+  } else {
+    sourceDir = window.prompt(t('sys.memoryImportPrompt')) || '';
+  }
+  if (!sourceDir) return;
+  const res = await window.ga.importMemory(sourceDir);
+  if (!res || res.ok === false) throw new Error((res && res.error) || 'import failed');
+  const detail = `memory: ${res.memoryCopied}, model_responses: ${res.responsesCopied}`
+    + (res.responsesSkipped ? ` (skip ${res.responsesSkipped})` : '')
+    + `, ${t('sys.memorySessions')}: ${res.sessionsAdded || 0}`
+    + (res.backupDir ? `\n${t('sys.memoryImportBackup')}: ${res.backupDir}` : '');
+  if (res.sessionsAdded) {
+    try { await loadSessions(); renderSessionList(); } catch (_) {}
+  }
+  showChanToast(t('sys.memoryImported'), detail, 'ok');
+}
+bindClick('import-memory-btn', async (e) => {
+  e.stopPropagation();
+  try {
+    await importMemoryFromDir();
+  } catch (err) {
+    showChanToast(t('err.memoryImport'), err.message || String(err), 'err');
+  }
+});
+const gaSourceCurrentEl = document.getElementById('ga-source-current');
+const gaSourceClearBtn = document.getElementById('ga-source-clear-btn');
+async function refreshGaSource() {
+  if (!window.__TAURI__?.core?.invoke) return;
+  let cur = '';
+  try { cur = await window.ga.getGaSource(); } catch (_) { cur = ''; }
+  if (gaSourceCurrentEl) {
+    if (cur) {
+      gaSourceCurrentEl.textContent = `${t('set.gaSourceCurrent')}: ${cur}`;
+      gaSourceCurrentEl.hidden = false;
+    } else {
+      gaSourceCurrentEl.hidden = true;
+    }
+  }
+  if (gaSourceClearBtn) gaSourceClearBtn.hidden = !cur;
+}
+bindClick('ga-source-btn', async (e) => {
+  e.stopPropagation();
+  if (!window.__TAURI__?.core?.invoke) {
+    showChanToast(t('err.gaSourceDesktopOnly'), '', 'err');
+    return;
+  }
+  try {
+    const dir = await window.ga.tauriInvoke('pick_directory', { title: t('sys.gaSourcePickTitle') });
+    if (!dir) return;
+    showChanToast(t('sys.gaSourceSwitching'), dir, 'ok');
+    const project = await window.ga.setGaSource(dir);
+    await refreshGaSource();
+    showChanToast(t('sys.gaSourceSet'), project || dir, 'ok');
+  } catch (err) {
+    showChanToast(t('err.gaSourceSet'), err.message || String(err), 'err');
+  }
+});
+bindClick('ga-source-clear-btn', async (e) => {
+  e.stopPropagation();
+  try {
+    showChanToast(t('sys.gaSourceSwitching'), '', 'ok');
+    await window.ga.clearGaSource();
+    await refreshGaSource();
+    showChanToast(t('sys.gaSourceCleared'), '', 'ok');
+  } catch (err) {
+    showChanToast(t('err.gaSourceSet'), err.message || String(err), 'err');
+  }
+});
+refreshGaSource();
 // 侧边栏「快速接入」：点击官方模型按钮 → 打开预填好的添加模型表单
 const pqEl = document.getElementById('provider-quickstart');
 if (pqEl) pqEl.addEventListener('click', (e) => {
diff --git a/frontends/desktop/static/i18n.js b/frontends/desktop/static/i18n.js
index e8e05cb7..5828e5bc 100644
--- a/frontends/desktop/static/i18n.js
+++ b/frontends/desktop/static/i18n.js
@@ -29,7 +29,7 @@
     'customPreset.removeTitle': '删除',
     'customPreset.editTitle': '编辑',
     'builtinPreset.restoreBtn': '恢复默认预设',
-    'set.appearance': '外观', 'set.plainUi': '素色', 'set.fontSize': '聊天字号', 'set.lang': '语言', 'set.model': '模型', 'set.addModel': '添加模型', 'set.features': '功能', 'set.importMykey': '导入已有模型配置（mykey.py）', 'set.exportMykey': '导出当前模型配置', 'set.serviceManager': '后台服务管理',
+    'set.appearance': '外观', 'set.plainUi': '素色', 'set.fontSize': '聊天字号', 'set.lang': '语言', 'set.model': '模型', 'set.addModel': '添加模型', 'set.features': '功能', 'set.importMykey': '导入已有模型配置（mykey.py）', 'set.exportMykey': '导出当前模型配置', 'set.importMemory': '导入已有记忆与会话记录（选择 GenericAgent 根目录）', 'set.gaSource': '接入独立 GenericAgent 源码（把桌面版当作壳）', 'set.gaSourceClear': '取消接入，改用内置版本', 'set.gaSourceCurrent': '当前接入', 'set.serviceManager': '后台服务管理',
     'shortcut.askConfirm': '是否在桌面创建 GenericAgent 快捷方式？',
     'appearance.light': '浅色', 'appearance.dark': '深色',
     'set.noModels': '暂无模型，点击下方添加',
@@ -150,6 +150,18 @@
     'sys.configSaved': '配置已保存',
     'sys.mykeyImported': '模型配置已导入',
     'sys.mykeyExported': '模型配置已导出',
+    'sys.memoryImported': '记忆已导入',
+    'err.memoryImport': '导入记忆失败',
+    'sys.memoryImportBackup': '原记忆已备份至',
+    'sys.memorySessions': '会话',
+    'sys.gaSourcePickTitle': '选择要接入的 GenericAgent 源码根目录（含 agentmain.py）',
+    'sys.gaSourceSwitching': '正在切换并重启后端...',
+    'sys.gaSourceSet': '已接入独立 GenericAgent',
+    'sys.gaSourceCleared': '已取消接入，恢复内置版本',
+    'err.gaSourceSet': '接入失败',
+    'err.gaSourceDesktopOnly': '此功能仅在桌面版中可用',
+    'sys.memoryPickTitle': '选择 GenericAgent 根目录（包含 memory 与 temp 的目录）',
+    'sys.memoryImportPrompt': '请输入 GenericAgent 根目录的完整路径（包含 memory 与 temp 的目录，而非 memory 文件夹本身）：',
     'st.starting': '启动中…', 'st.stopping': '停止中…', 'st.online': '在线', 'st.offline': '离线', 'st.error': '错误', 'st.running': '运行', 'st.abnormal': '异常',
     'act.configure': '配置', 'act.logs': '日志', 'act.restart': '重启', 'act.stop': '停止', 'act.start': '启动', 'act.exit': '退出',
     'act.copy': '复制', 'act.copied': '已复制', 'act.copyTex': 'TeX', 'act.send': '发送',
@@ -202,7 +214,7 @@
     'customPreset.removeTitle': 'Delete',
     'customPreset.editTitle': 'Edit',
     'builtinPreset.restoreBtn': 'Restore defaults',
-    'set.appearance': 'Appearance', 'set.plainUi': 'Plain', 'set.fontSize': 'Chat font size', 'set.lang': 'Language', 'set.model': 'Model', 'set.addModel': 'Add model', 'set.features': 'Features', 'set.importMykey': 'Import model config (mykey.py)', 'set.exportMykey': 'Export current model config', 'set.serviceManager': 'Service manager',
+    'set.appearance': 'Appearance', 'set.plainUi': 'Plain', 'set.fontSize': 'Chat font size', 'set.lang': 'Language', 'set.model': 'Model', 'set.addModel': 'Add model', 'set.features': 'Features', 'set.importMykey': 'Import model config (mykey.py)', 'set.exportMykey': 'Export current model config', 'set.importMemory': 'Import existing memory & sessions (select GenericAgent root)', 'set.gaSource': 'Connect to a separate GenericAgent source (use desktop as a shell)', 'set.gaSourceClear': 'Disconnect, use the bundled version', 'set.gaSourceCurrent': 'Connected to', 'set.serviceManager': 'Service manager',
     'shortcut.askConfirm': 'Create a desktop shortcut for GenericAgent?',
     'appearance.light': 'Light', 'appearance.dark': 'Dark',
     'set.noModels': 'No models yet — add one below',
@@ -323,6 +335,18 @@
     'sys.configSaved': 'Configuration saved',
     'sys.mykeyImported': 'Model config imported',
     'sys.mykeyExported': 'Model config exported',
+    'sys.memoryImported': 'Memory imported',
+    'err.memoryImport': 'Failed to import memory',
+    'sys.memoryImportBackup': 'Previous memory backed up to',
+    'sys.memorySessions': 'sessions',
+    'sys.gaSourcePickTitle': 'Select the GenericAgent source root to connect to (contains agentmain.py)',
+    'sys.gaSourceSwitching': 'Switching and restarting the backend...',
+    'sys.gaSourceSet': 'Connected to the external GenericAgent',
+    'sys.gaSourceCleared': 'Disconnected, restored the bundled version',
+    'err.gaSourceSet': 'Failed to connect',
+    'err.gaSourceDesktopOnly': 'This feature is only available in the desktop app',
+    'sys.memoryPickTitle': 'Select the GenericAgent root directory (the folder containing memory and temp)',
+    'sys.memoryImportPrompt': 'Enter the full path of the GenericAgent root directory (the folder containing memory and temp, not the memory folder itself):',
     'st.starting': 'Starting…', 'st.stopping': 'Stopping…', 'st.online': 'Online', 'st.offline': 'Offline', 'st.error': 'Error', 'st.running': 'Running', 'st.abnormal': 'Error',
     'act.configure': 'Configure', 'act.logs': 'Logs', 'act.restart': 'Restart', 'act.stop': 'Stop', 'act.start': 'Start', 'act.exit': 'Exit',
     'act.copy': 'Copy', 'act.copied': 'Copied', 'act.copyTex': 'TeX', 'act.send': 'Send',
diff --git a/frontends/desktop/static/index.html b/frontends/desktop/static/index.html
index bc0ff956..ef62a7c1 100644
--- a/frontends/desktop/static/index.html
+++ b/frontends/desktop/static/index.html
@@ -649,6 +649,19 @@
             <span data-ga-icon="folderSimple"></span>
             <span data-i18n="set.exportMykey"></span>
           </button>
+          <button class="set-btn set-btn-follow" id="import-memory-btn" type="button">
+            <span data-ga-icon="folderSimple"></span>
+            <span data-i18n="set.importMemory"></span>
+          </button>
+          <button class="set-btn set-btn-follow" id="ga-source-btn" type="button">
+            <span data-ga-icon="folderSimple"></span>
+            <span data-i18n="set.gaSource"></span>
+          </button>
+          <div class="set-hint" id="ga-source-current" hidden></div>
+          <button class="set-btn set-btn-follow" id="ga-source-clear-btn" type="button" hidden>
+            <span data-ga-icon="x"></span>
+            <span data-i18n="set.gaSourceClear"></span>
+          </button>
           <button class="set-btn set-btn-follow" id="settings-services-btn" type="button">
             <span data-ga-icon="broadcast"></span>
             <span data-i18n="set.serviceManager"></span>
@@ -675,6 +688,6 @@
 <script src="https://cdn.jsdelivr.net/gh/highlightjs/cdn-release@11.9.0/build/highlight.min.js" crossorigin="anonymous"></script>
 <script src="phosphor-icons.js?v=2"></script>
 <script src="i18n.js?v=1"></script>
-<script src="app.js?v=216"></script>
+<script src="app.js?v=217"></script>
 </body>
 </html>
diff --git a/frontends/desktop_bridge.py b/frontends/desktop_bridge.py
index a42693b0..0eec01f5 100644
--- a/frontends/desktop_bridge.py
+++ b/frontends/desktop_bridge.py
@@ -36,7 +36,7 @@ WS API (state sync):
 """
 from __future__ import annotations
 
-import asyncio, atexit, contextlib, importlib, json, os, re, subprocess, sys
+import asyncio, atexit, contextlib, importlib, json, os, re, shutil, subprocess, sys
 from collections import Counter, deque
 import threading, time, traceback, uuid
 from dataclasses import dataclass, field
@@ -148,6 +148,8 @@ class AgentManager:
         self.config: Dict[str, Any] = {}
         self.sessions: Dict[str, Session] = {}
         self.active_session_id: Optional[str] = None
+        self._sessions_dir = Path(self.ga_root) / "temp" / "desktop_sessions"
+        # Legacy monolithic store; migrated into _sessions_dir on first load, then retired.
         self._sessions_file = Path(self.ga_root) / "temp" / "desktop_sessions.json"
         self._load_sessions()
 
@@ -155,56 +157,157 @@ class AgentManager:
     def mykey_path(self) -> str:
         return str(Path(self.ga_root) / "mykey.py")
 
-    def _persist(self):
+    def _session_dict(self, s: "Session") -> dict:
+        llm_hist = None
+        if s.agent and hasattr(s.agent, 'llmclient'):
+            try: llm_hist = s.agent.llmclient.backend.history
+            except Exception: pass
+        if llm_hist is None:
+            llm_hist = s.llm_history
+        return {"id": s.id, "title": s.title, "cwd": s.cwd,
+                "created_at": s.created_at, "updated_at": s.updated_at,
+                "messages": s.messages, "msg_seq": s.msg_seq,
+                "pinned": s.pinned, "untitled": s.untitled,
+                "plan_scan_baseline": s.plan_scan_baseline,
+                "plan_path": s.plan_path or "",
+                "llm_no": s.llm_no,
+                "llm_history": llm_hist}
+
+    def _session_file(self, sid: str) -> Path:
+        return self._sessions_dir / f"{sid}.json"
+
+    def _persist_session(self, s: "Session"):
+        """Write a single session file. Cost is O(one session), independent of how many
+        sessions exist — this is the fix for the monolithic-file scaling problem."""
         try:
-            self._sessions_file.parent.mkdir(parents=True, exist_ok=True)
-            arr = []
+            self._sessions_dir.mkdir(parents=True, exist_ok=True)
             with self.lock:
-                for s in self.sessions.values():
-                    llm_hist = None
-                    if s.agent and hasattr(s.agent, 'llmclient'):
-                        try: llm_hist = s.agent.llmclient.backend.history
-                        except Exception: pass
-                    if llm_hist is None:
-                        llm_hist = s.llm_history
-                    arr.append({"id": s.id, "title": s.title, "cwd": s.cwd,
-                                "created_at": s.created_at, "updated_at": s.updated_at,
-                                "messages": s.messages, "msg_seq": s.msg_seq,
-                                "pinned": s.pinned, "untitled": s.untitled,
-                                "plan_scan_baseline": s.plan_scan_baseline,
-                                "plan_path": s.plan_path or "",
-                                "llm_no": s.llm_no,
-                                "llm_history": llm_hist})
-            self._sessions_file.write_text(json.dumps(arr, ensure_ascii=False, default=str), encoding="utf-8")
+                data = self._session_dict(s)
+            tmp = self._sessions_dir / f"{s.id}.json.tmp"
+            tmp.write_text(json.dumps(data, ensure_ascii=False, default=str), encoding="utf-8")
+            os.replace(tmp, self._session_file(s.id))  # atomic swap
         except Exception as e:
-            print(f"[bridge] persist sessions failed: {e}", file=sys.stderr)
+            print(f"[bridge] persist session {s.id} failed: {e}", file=sys.stderr)
+
+    def _delete_session_file(self, sid: str):
+        try:
+            f = self._session_file(sid)
+            if f.exists():
+                f.unlink()
+        except Exception as e:
+            print(f"[bridge] delete session file {sid} failed: {e}", file=sys.stderr)
+
+    def _persist(self):
+        """Write every session (one file each). Used for bulk ops (import) / full flush."""
+        with self.lock:
+            sessions = list(self.sessions.values())
+        for s in sessions:
+            self._persist_session(s)
+
+    def _session_from_item(self, item: dict) -> "Session":
+        msgs = item.get("messages", [])
+        return Session(id=item["id"], title=item.get("title", "New chat"),
+                       cwd=item.get("cwd", self.ga_root),
+                       created_at=item.get("created_at", time.time()),
+                       updated_at=item.get("updated_at", time.time()),
+                       messages=msgs,
+                       msg_seq=item.get("msg_seq", 0),
+                       pinned=item.get("pinned", False),
+                       untitled=item.get("untitled", True),
+                       plan_scan_baseline=_load_plan_baseline(item, msgs),
+                       plan_path=_sanitize_desktop_plan_path(item["id"], item.get("plan_path") or ""),
+                       status="idle", agent=None,
+                       llm_history=item.get("llm_history"),
+                       llm_no=item.get("llm_no"))
 
     def _load_sessions(self):
+        # New format: one file per session under temp/desktop_sessions/.
         try:
-            if not self._sessions_file.exists():
-                return
-            arr = json.loads(self._sessions_file.read_text(encoding="utf-8"))
-            for item in arr:
-                msgs = item.get("messages", [])
-                sess = Session(id=item["id"], title=item.get("title", "New chat"),
-                               cwd=item.get("cwd", self.ga_root),
-                               created_at=item.get("created_at", time.time()),
-                               updated_at=item.get("updated_at", time.time()),
-                               messages=msgs,
-                               msg_seq=item.get("msg_seq", 0),
-                               pinned=item.get("pinned", False),
-                               untitled=item.get("untitled", True),
-                               plan_scan_baseline=_load_plan_baseline(item, msgs),
-                               plan_path=_sanitize_desktop_plan_path(
-                                   item["id"], item.get("plan_path") or ""),
-                               status="idle", agent=None,
-                               llm_history=item.get("llm_history"),
-                               llm_no=item.get("llm_no"))
-                self.sessions[sess.id] = sess
-            if self.sessions:
-                self.active_session_id = max(self.sessions.values(), key=lambda s: s.updated_at).id
+            if self._sessions_dir.is_dir():
+                for f in self._sessions_dir.glob("*.json"):
+                    try:
+                        item = json.loads(f.read_text(encoding="utf-8"))
+                        sess = self._session_from_item(item)
+                        self.sessions[sess.id] = sess
+                    except Exception as e:
+                        print(f"[bridge] load session {f.name} failed: {e}", file=sys.stderr)
         except Exception as e:
-            print(f"[bridge] load sessions failed: {e}", file=sys.stderr)
+            print(f"[bridge] load sessions dir failed: {e}", file=sys.stderr)
+
+        # One-time migration from the legacy monolithic desktop_sessions.json.
+        try:
+            if self._sessions_file.exists():
+                arr = json.loads(self._sessions_file.read_text(encoding="utf-8"))
+                for item in arr:
+                    if not isinstance(item, dict) or item.get("id") in self.sessions:
+                        continue
+                    try:
+                        sess = self._session_from_item(item)
+                        self.sessions[sess.id] = sess
+                        self._persist_session(sess)
+                    except Exception as e:
+                        print(f"[bridge] migrate session failed: {e}", file=sys.stderr)
+                # Retire the legacy file so we do not migrate again next launch.
+                with contextlib.suppress(Exception):
+                    self._sessions_file.rename(
+                        self._sessions_file.parent / (self._sessions_file.name + ".migrated"))
+        except Exception as e:
+            print(f"[bridge] migrate sessions failed: {e}", file=sys.stderr)
+
+        if self.sessions:
+            self.active_session_id = max(self.sessions.values(), key=lambda s: s.updated_at).id
+
+    def import_sessions(self, source_dir: str) -> dict:
+        """把 source 的桌面会话合并进当前列表(按 id 去重)。
+
+        兼容两种源格式:新版 temp/desktop_sessions/<id>.json,以及旧版单文件
+        temp/desktop_sessions.json(含已退休的 .migrated)。只落盘新增的会话。
+        """
+        src = Path(source_dir).expanduser().resolve()
+        items: List[dict] = []
+        found = False
+
+        # New per-session format.
+        src_dir = src / "temp" / "desktop_sessions"
+        if src_dir.is_dir():
+            for f in src_dir.glob("*.json"):
+                try:
+                    items.append(json.loads(f.read_text(encoding="utf-8")))
+                    found = True
+                except Exception:
+                    continue
+
+        # Legacy monolithic format (live or already retired).
+        for legacy in (src / "temp" / "desktop_sessions.json",
+                       src / "temp" / "desktop_sessions.json.migrated"):
+            if legacy.is_file():
+                found = True
+                try:
+                    arr = json.loads(legacy.read_text(encoding="utf-8"))
+                    if isinstance(arr, list):
+                        items.extend(x for x in arr if isinstance(x, dict))
+                except Exception:
+                    continue
+
+        if not found:
+            return {"sessionsAdded": 0, "sessionsSkipped": 0, "sessionsFileFound": False}
+
+        added = 0
+        skipped = 0
+        new_sessions: List["Session"] = []
+        with self.lock:
+            for item in items:
+                sid = item.get("id")
+                if not sid or sid in self.sessions:
+                    skipped += 1
+                    continue
+                sess = self._session_from_item(item)
+                self.sessions[sid] = sess
+                new_sessions.append(sess)
+                added += 1
+        for sess in new_sessions:
+            self._persist_session(sess)
+        return {"sessionsAdded": added, "sessionsSkipped": skipped, "sessionsFileFound": True}
 
     def _mykey_file(self) -> Path:
         p = Path(self.ga_root) / "mykey.py"
@@ -571,7 +674,7 @@ class AgentManager:
         sess.updated_at = time.time()
         if role == "user" and content.strip() and sess.title == "New chat":
             sess.title = content.strip().replace("\n", " ")[:40]
-        self._persist()
+        self._persist_session(sess)
         return msg
 
     def create_session(self, cwd: Optional[str] = None) -> Session:
@@ -581,7 +684,7 @@ class AgentManager:
             self.sessions[sid] = sess
             self.active_session_id = sid
         emit_session_state(sess, "created")
-        self._persist()
+        self._persist_session(sess)
         return sess
 
     def get_session(self, sid: str) -> Session:
@@ -602,7 +705,7 @@ class AgentManager:
                 with contextlib.suppress(Exception):
                     sess.agent.abort()
         emit_session_state(sess, "closed")
-        self._persist()
+        self._delete_session_file(sid)
         _purge_session_uploads(sid)
         return {"ok": True, "sessionId": sid}
 
@@ -837,7 +940,7 @@ class AgentManager:
                 with contextlib.suppress(Exception):
                     sess.agent.next_llm(int(llm_no))
             sess.updated_at = time.time()
-        self._persist()
+        self._persist_session(sess)
         return {"ok": True, "sessionId": sid, "llmNo": sess.llm_no, "model": self._live_model(sess)}
 
 
@@ -1442,7 +1545,7 @@ async def patch_session_handler(request):
     if "plan_scan_baseline" in data:
         sess.plan_scan_baseline = int(data["plan_scan_baseline"])
     sess.updated_at = time.time()
-    manager._persist()
+    manager._persist_session(sess)
     return json_ok({"ok": True, "session": manager.snapshot(sess, include_messages=False)})
 
 
@@ -1748,6 +1851,87 @@ async def mykey_save_handler(request):
     return json_ok({"ok": True, "path": str(manager._mykey_file()), "profiles": profiles})
 
 
+def _import_memory_from(source_dir: str, ga_root: str) -> dict:
+    """把 source_dir 的 memory/ 与 temp/model_responses/ 导入到 ga_root。
+
+    memory/: 先整体备份现有 ga_root/memory 到 temp/memory_import_backup_<ts>/,再覆盖同名文件、补齐新文件。
+    temp/model_responses/: 文件名带 pid/logid 天然唯一,只拷目标端不存在的,已存在的跳过。
+    """
+    src = Path(source_dir).expanduser().resolve()
+    dst_root = Path(ga_root).resolve()
+    if not src.is_dir():
+        raise ValueError(f"source is not a directory: {src}")
+    if src == dst_root:
+        raise ValueError("source is the same as current GA root")
+
+    src_mem = src / "memory"
+    src_resp = src / "temp" / "model_responses"
+    if not src_mem.is_dir() and not src_resp.is_dir():
+        raise ValueError("not a GA directory (no memory/ or temp/model_responses/)")
+
+    memory_copied = 0
+    responses_copied = 0
+    responses_skipped = 0
+    backup_dir = ""
+
+    # --- memory/: 备份后覆盖 ---
+    if src_mem.is_dir():
+        dst_mem = dst_root / "memory"
+        if dst_mem.is_dir() and any(dst_mem.iterdir()):
+            ts = time.strftime("%Y%m%d_%H%M%S")
+            backup_root = dst_root / "temp" / f"memory_import_backup_{ts}"
+            backup_root.mkdir(parents=True, exist_ok=True)
+            shutil.copytree(dst_mem, backup_root / "memory")
+            backup_dir = str(backup_root)
+        dst_mem.mkdir(parents=True, exist_ok=True)
+        for item in src_mem.rglob("*"):
+            rel = item.relative_to(src_mem)
+            target = dst_mem / rel
+            if item.is_dir():
+                target.mkdir(parents=True, exist_ok=True)
+            else:
+                target.parent.mkdir(parents=True, exist_ok=True)
+                shutil.copy2(item, target)
+                memory_copied += 1
+
+    # --- temp/model_responses/: 补齐缺失 ---
+    if src_resp.is_dir():
+        dst_resp = dst_root / "temp" / "model_responses"
+        dst_resp.mkdir(parents=True, exist_ok=True)
+        for item in src_resp.rglob("*"):
+            if item.is_dir():
+                continue
+            rel = item.relative_to(src_resp)
+            target = dst_resp / rel
+            if target.exists():
+                responses_skipped += 1
+                continue
+            target.parent.mkdir(parents=True, exist_ok=True)
+            shutil.copy2(item, target)
+            responses_copied += 1
+
+    return {
+        "ok": True,
+        "memoryCopied": memory_copied,
+        "responsesCopied": responses_copied,
+        "responsesSkipped": responses_skipped,
+        "backupDir": backup_dir,
+    }
+
+
+async def memory_import_handler(request):
+    data = await read_json(request)
+    source_dir = (data.get("sourceDir") or "").strip()
+    if not source_dir:
+        return json_ok({"ok": False, "error": "missing_sourceDir"}, status=400)
+    try:
+        result = _import_memory_from(source_dir, manager.ga_root)
+        result.update(manager.import_sessions(source_dir))
+    except Exception as e:
+        return json_ok({"ok": False, "error": str(e)}, status=400)
+    return json_ok(result)
+
+
 async def conductor_model_get_handler(request):
     return json_ok({"model": _conductor_settings()})
 
@@ -1922,6 +2106,7 @@ def create_app():
     app.router.add_get("/services/panel", service_panel_handler)
     app.router.add_get("/services/mykey", mykey_get_handler)
     app.router.add_post("/services/mykey", mykey_save_handler)
+    app.router.add_post("/memory/import", memory_import_handler)
     app.router.add_get("/services/conductor/model", conductor_model_get_handler)
     app.router.add_post("/services/conductor/model", conductor_model_save_handler)
     app.router.add_post("/services/stop-extras", stop_extras_handler)