diff --git a/modules/host_workspace_manager.py b/modules/host_workspace_manager.py
index 5174925..293d93a 100644
--- a/modules/host_workspace_manager.py
+++ b/modules/host_workspace_manager.py
@@ -338,8 +338,43 @@ def delete_host_workspace(
     }
 
 
+def set_default_host_workspace(
+    workspace_id: str,
+    config_path: Optional[Union[str, Path]] = None,
+) -> Dict[str, Any]:
+    """设置指定工作区为默认工作区。"""
+    ws_id = str(workspace_id or "").strip()
+    if not ws_id:
+        raise ValueError("缺少 workspace_id")
+
+    cfg_path = _resolve_config_path(config_path)
+    with _HOST_WORKSPACE_LOCK:
+        payload = _ensure_config_file(cfg_path, strict=True)
+        raw_workspaces = payload.get("workspaces")
+        if not isinstance(raw_workspaces, list):
+            raw_workspaces = []
+
+        seen_ids = set()
+        for idx, item in enumerate(raw_workspaces):
+            normalized = _normalize_entry(item, idx)
+            if normalized:
+                seen_ids.add(normalized.get("workspace_id"))
+
+        if ws_id not in seen_ids:
+            raise ValueError("工作区不存在")
+
+        payload["default_workspace_id"] = ws_id
+        _atomic_write_json(cfg_path, payload)
+
+    return {
+        "default_workspace_id": ws_id,
+        "catalog": load_host_workspace_catalog(config_path=cfg_path),
+    }
+
+
 __all__ = [
     "load_host_workspace_catalog",
     "resolve_host_workspace",
     "create_host_workspace",
+    "set_default_host_workspace",
 ]
diff --git a/modules/user_manager.py b/modules/user_manager.py
index f6f2001..fa3a35e 100644
--- a/modules/user_manager.py
+++ b/modules/user_manager.py
@@ -36,6 +36,7 @@ class UserRecord:
     invite_code: Optional[str] = None
     role: str = "user"
     tutorial_completed: bool = False
+    default_workspace_id: str = "default"
 
 
 @dataclass
@@ -390,6 +391,14 @@ class UserManager:
         workspace.workspace_id = workspace_id
         return workspace
 
+    def _get_user_default_workspace_id(self, username: str) -> str:
+        """返回用户设置的默认项目 ID，如未设置或无效则返回 default。"""
+        record = self._users.get(self._normalize_username(username))
+        default_id = str(getattr(record, "default_workspace_id", None) or "default").strip()
+        if not default_id:
+            return "default"
+        return default_id
+
     def list_user_workspaces(self, username: str) -> Dict[str, Dict]:
         username = self._normalize_username(username)
         self._migrate_legacy_docker_workspace_layout(username)
@@ -404,15 +413,21 @@ class UserManager:
             if web_root.exists():
                 self._collect_workspaces(result, web_root)
 
+        default_workspace_id = self._get_user_default_workspace_id(username)
+
         # 确保 default 始终存在
         if "default" not in result:
             result["default"] = {
                 "workspace_id": "default",
                 "label": "默认项目",
                 "path": "",
-                "is_default": True,
+                "is_default": default_workspace_id == "default",
                 "has_conversations": False,
             }
+
+        # 同步 is_default 标记
+        for ws_id in result:
+            result[ws_id]["is_default"] = ws_id == default_workspace_id
         return result
 
     def _collect_workspaces(self, result: Dict[str, Dict], projects_root: Path) -> None:
@@ -519,6 +534,20 @@ class UserManager:
             raise ValueError("项目不存在")
         shutil.rmtree(target)
 
+    def set_default_user_workspace(self, username: str, workspace_id: str) -> str:
+        """设置指定项目为用户默认项目，返回生效的默认项目 ID。"""
+        username = self._normalize_username(username)
+        ws_id = self.normalize_workspace_id(workspace_id)
+        known = self.list_user_workspaces(username)
+        if ws_id not in known:
+            raise ValueError("项目不存在")
+        record = self._users.get(username)
+        if not record:
+            raise ValueError("用户不存在")
+        record.default_workspace_id = ws_id
+        self._save_users()
+        return ws_id
+
     @staticmethod
     def _load_workspace_label(workspace_root: Path, fallback: str) -> str:
         meta_path = workspace_root / "project.json"
@@ -652,9 +681,12 @@ class UserManager:
                         invite_code=payload.get("invite_code"),
                         role=payload.get("role", "user"),
                         tutorial_completed=bool(payload.get("tutorial_completed", False)),
+                        default_workspace_id=str(payload.get("default_workspace_id") or "default").strip() or "default",
                     )
                     if "tutorial_completed" not in payload:
                         migrated = True
+                    if "default_workspace_id" not in payload:
+                        migrated = True
                     self._users[username] = record
                     self._index_user(record)
             if migrated:
@@ -672,6 +704,7 @@ class UserManager:
                     "invite_code": record.invite_code,
                     "role": record.role,
                     "tutorial_completed": bool(record.tutorial_completed),
+                    "default_workspace_id": str(record.default_workspace_id or "default").strip() or "default",
                 }
                 for username, record in self._users.items()
             }
diff --git a/server/status.py b/server/status.py
index 76273a8..48bdf0f 100644
--- a/server/status.py
+++ b/server/status.py
@@ -27,6 +27,7 @@ from modules.host_workspace_manager import (
     load_host_workspace_catalog,
     rename_host_workspace,
     resolve_host_workspace,
+    set_default_host_workspace,
 )
 from utils.host_workspace_debug import write_host_workspace_debug
 from .utils_common import log_conn_diag
@@ -49,14 +50,15 @@ def _close_terminal_for_key(term_key: str):
 
 def _build_docker_projects_payload(username: str, current_id: str) -> list[dict]:
     running_by_workspace = _active_task_counts(username)
+    workspaces = user_manager.list_user_workspaces(username)
     projects = []
-    for ws_id, item in user_manager.list_user_workspaces(username).items():
+    for ws_id, item in workspaces.items():
         projects.append({
             "workspace_id": ws_id,
             "label": item.get("label") or ("默认项目" if ws_id == "default" else ws_id),
             "path": "",
             "is_current": ws_id == current_id,
-            "is_default": ws_id == "default",
+            "is_default": bool(item.get("is_default", ws_id == "default")),
             "running_task_count": int(running_by_workspace.get(ws_id, 0)),
         })
     return projects
@@ -1051,10 +1053,11 @@ def list_docker_projects():
     # 默认项目用于向后兼容旧 Docker Web 文件/对话。
     user_manager.ensure_user_workspace(username, current_id)
     projects = _build_docker_projects_payload(username, current_id)
+    default_workspace_id = user_manager._get_user_default_workspace_id(username)
     return jsonify({
         "success": True,
         "data": {
-            "default_workspace_id": "default",
+            "default_workspace_id": default_workspace_id,
             "current_workspace_id": current_id,
             "workspaces": projects,
         }
@@ -1100,12 +1103,13 @@ def select_docker_project():
             attach_user_broadcast(terminal, username)
         except Exception:
             pass
+    default_workspace_id = user_manager._get_user_default_workspace_id(username)
     return jsonify({
         "success": True,
             "data": {
                 "current_workspace_id": session["workspace_id"],
                 "project_path": "",
-                "default_workspace_id": "default",
+                "default_workspace_id": default_workspace_id,
                 "reloaded": previous_workspace_id != session["workspace_id"],
             }
         })
@@ -1127,13 +1131,14 @@ def create_docker_project():
         return jsonify({"success": False, "error": str(exc)}), 400
     projects = []
     current_id = session.get("workspace_id") or "default"
+    default_workspace_id = user_manager._get_user_default_workspace_id(username)
     for ws_id, item in user_manager.list_user_workspaces(username).items():
         projects.append({
             "workspace_id": ws_id,
             "label": item.get("label") or ws_id,
             "path": "",
             "is_current": ws_id == current_id,
-            "is_default": ws_id == "default",
+            "is_default": ws_id == default_workspace_id,
         })
     return jsonify({
         "success": True,
@@ -1144,7 +1149,7 @@ def create_docker_project():
                 "label": label,
                 "path": "",
             },
-            "default_workspace_id": "default",
+            "default_workspace_id": default_workspace_id,
             "current_workspace_id": current_id,
             "workspaces": projects,
         }
@@ -1169,11 +1174,12 @@ def rename_docker_project():
     except ValueError as exc:
         return jsonify({"success": False, "error": str(exc)}), 400
     current_id = session.get("workspace_id") or "default"
+    default_workspace_id = user_manager._get_user_default_workspace_id(username)
     return jsonify({
         "success": True,
         "data": {
             "workspace": workspace,
-            "default_workspace_id": "default",
+            "default_workspace_id": default_workspace_id,
             "current_workspace_id": current_id,
             "workspaces": _build_docker_projects_payload(username, current_id),
         }
@@ -1218,11 +1224,20 @@ def delete_docker_project():
             )
         except RuntimeError as exc:
             return jsonify({"success": False, "error": str(exc)}), 503
+
+    # 如果删除的是当前默认项目，重置为 default
+    if user_manager._get_user_default_workspace_id(username) == workspace_id:
+        try:
+            user_manager.set_default_user_workspace(username, "default")
+        except Exception:
+            pass
+
+    default_workspace_id = user_manager._get_user_default_workspace_id(username)
     return jsonify({
         "success": True,
         "data": {
             "deleted_workspace_id": workspace_id,
-            "default_workspace_id": "default",
+            "default_workspace_id": default_workspace_id,
             "current_workspace_id": current_id,
             "workspaces": _build_docker_projects_payload(username, current_id),
         }
@@ -1474,6 +1489,64 @@ def delete_host_workspace_api():
     })
 
 
+@status_bp.route('/api/host/workspaces/set-default', methods=['POST'])
+@api_login_required
+def set_default_host_workspace_api():
+    if not _is_host_mode_request():
+        return jsonify({"success": False, "error": "仅宿主机模式可用"}), 403
+
+    payload = request.get_json(silent=True) or {}
+    workspace_id = (payload.get("workspace_id") or "").strip()
+    if not workspace_id:
+        return jsonify({"success": False, "error": "缺少 workspace_id"}), 400
+    try:
+        result = set_default_host_workspace(workspace_id)
+    except ValueError as exc:
+        return jsonify({"success": False, "error": str(exc)}), 400
+    except Exception as exc:
+        return jsonify({"success": False, "error": str(exc)}), 500
+
+    catalog = result.get("catalog") or load_host_workspace_catalog()
+    current_id = (session.get("host_workspace_id") or "").strip()
+    return jsonify({
+        "success": True,
+        "data": {
+            "default_workspace_id": catalog.get("default_workspace_id"),
+            "current_workspace_id": current_id,
+            "workspaces": _build_host_workspaces_payload(catalog, current_id),
+        }
+    })
+
+
+@status_bp.route('/api/projects/set-default', methods=['POST'])
+@api_login_required
+def set_default_docker_project_api():
+    if not _is_docker_project_request():
+        return jsonify({"success": False, "error": "仅 Docker Web 模式可用"}), 403
+
+    payload = request.get_json(silent=True) or {}
+    workspace_id = (payload.get("workspace_id") or "").strip()
+    if not workspace_id:
+        return jsonify({"success": False, "error": "缺少项目 ID"}), 400
+    username = session.get("username")
+    try:
+        user_manager.set_default_user_workspace(username, workspace_id)
+    except ValueError as exc:
+        return jsonify({"success": False, "error": str(exc)}), 400
+    except Exception as exc:
+        return jsonify({"success": False, "error": str(exc)}), 500
+
+    current_id = session.get("workspace_id") or "default"
+    return jsonify({
+        "success": True,
+        "data": {
+            "default_workspace_id": user_manager._get_user_default_workspace_id(username),
+            "current_workspace_id": current_id,
+            "workspaces": _build_docker_projects_payload(username, current_id),
+        }
+    })
+
+
 @status_bp.route('/api/container-status')
 @api_login_required
 @with_terminal
diff --git a/static/src/App.vue b/static/src/App.vue
index 08d409d..2758711 100644
--- a/static/src/App.vue
+++ b/static/src/App.vue
@@ -551,6 +551,7 @@
           @create="submitHostWorkspaceCreateFromManage"
           @rename="renameHostWorkspace"
           @delete="deleteHostWorkspace"
+          @set-default="setDefaultHostWorkspace"
         />
       </transition>
       <TutorialOverlay v-if="tutorialStore.running" />
diff --git a/static/src/app/methods/ui.ts b/static/src/app/methods/ui.ts
index f1cd03a..a12c547 100644
--- a/static/src/app/methods/ui.ts
+++ b/static/src/app/methods/ui.ts
@@ -1474,6 +1474,52 @@ export const uiMethods = {
     }
   },
 
+  async setDefaultHostWorkspace(payload = {}) {
+    if (!(this.versioningHostMode || this.dockerProjectMode)) {
+      return;
+    }
+    const workspaceId = String(payload?.workspace_id || '').trim();
+    if (!workspaceId) return;
+    if (workspaceId === this.defaultHostWorkspaceId) return;
+
+    this.hostWorkspaceManageSubmitting = true;
+    this.hostWorkspaceCreateError = '';
+    const kindLabel = this.versioningHostMode ? '工作区' : '项目';
+    try {
+      const endpoint = this.versioningHostMode
+        ? '/api/host/workspaces/set-default'
+        : '/api/projects/set-default';
+      const resp = await fetch(endpoint, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        credentials: 'same-origin',
+        body: JSON.stringify({ workspace_id: workspaceId })
+      });
+      const result = await resp.json().catch(() => ({}));
+      if (!resp.ok || !result?.success) {
+        throw new Error(result?.error || `设置默认${kindLabel}失败`);
+      }
+      const data = result.data || {};
+      this.defaultHostWorkspaceId = String(data.default_workspace_id || workspaceId);
+      await this.fetchHostWorkspaces();
+      this.uiPushToast({
+        title: `已设为默认${kindLabel}`,
+        message: (this.hostWorkspaces || []).find((w: any) => w.workspace_id === workspaceId)?.label || workspaceId,
+        type: 'success'
+      });
+    } catch (error) {
+      const message = error instanceof Error ? error.message : String(error || `设置默认${kindLabel}失败`);
+      this.hostWorkspaceCreateError = message;
+      this.uiPushToast({
+        title: `设置默认${kindLabel}失败`,
+        message,
+        type: 'error'
+      });
+    } finally {
+      this.hostWorkspaceManageSubmitting = false;
+    }
+  },
+
   fetchTodoList() {
     return this.fileFetchTodoList();
   },
diff --git a/static/src/components/overlay/HostWorkspaceManageDialog.vue b/static/src/components/overlay/HostWorkspaceManageDialog.vue
index e697357..b5387ac 100644
--- a/static/src/components/overlay/HostWorkspaceManageDialog.vue
+++ b/static/src/components/overlay/HostWorkspaceManageDialog.vue
@@ -77,12 +77,24 @@
                   {{ item.path || '（未配置路径）' }}
                 </div>
                 <div class="workspace-manage-badges">
+                  <span v-if="item.workspace_id === defaultWorkspaceId" class="workspace-manage-badge default">
+                    默认
+                  </span>
                   <span v-if="Number(item.running_task_count || 0) > 0" class="workspace-manage-badge running">
                     运行中
                   </span>
                 </div>
               </div>
               <div class="workspace-manage-actions">
+                <button
+                  type="button"
+                  class="host-workspace-dialog__btn ghost"
+                  :class="{ active: item.workspace_id === defaultWorkspaceId }"
+                  :disabled="busy || item.workspace_id === defaultWorkspaceId"
+                  @click="submitSetDefault(item)"
+                >
+                  {{ item.workspace_id === defaultWorkspaceId ? '已默认' : '设为默认' }}
+                </button>
                 <button
                   type="button"
                   class="host-workspace-dialog__btn ghost"
@@ -140,6 +152,7 @@ const emits = defineEmits<{
   (event: 'create', payload: { path: string; label: string }): void;
   (event: 'rename', payload: { workspace_id: string; label: string }): void;
   (event: 'delete', item: WorkspaceItem): void;
+  (event: 'setDefault', payload: { workspace_id: string }): void;
 }>();
 
 const workspaceKind = props.workspaceKind || 'workspace';
@@ -190,6 +203,11 @@ const submitRename = (item: WorkspaceItem) => {
     label: String(renameDrafts[item.workspace_id] ?? '').trim()
   });
 };
+
+const submitSetDefault = (item: WorkspaceItem) => {
+  if (item.workspace_id === props.defaultWorkspaceId) return;
+  emits('setDefault', { workspace_id: item.workspace_id });
+};
 </script>
 
 <style scoped>
@@ -368,6 +386,11 @@ const submitRename = (item: WorkspaceItem) => {
   color: var(--claude-accent);
 }
 
+.workspace-manage-badge.default {
+  color: var(--state-success);
+  border-color: color-mix(in srgb, var(--state-success) 45%, var(--theme-control-border-strong));
+}
+
 .workspace-manage-empty {
   font-size: 13px;
   color: var(--claude-text-secondary);
diff --git a/static/src/components/panels/LeftPanel.vue b/static/src/components/panels/LeftPanel.vue
index 2ec0857..3e867ef 100644
--- a/static/src/components/panels/LeftPanel.vue
+++ b/static/src/components/panels/LeftPanel.vue
@@ -222,6 +222,12 @@
                     <div class="host-workspace-card-head">
                       <span class="host-workspace-label">{{ item.label }}</span>
                       <span class="host-workspace-badges">
+                        <span
+                          v-if="item.workspace_id === hostWorkspaceDefaultId"
+                          class="host-workspace-badge default"
+                        >
+                          默认
+                        </span>
                         <span
                           v-if="Number(item.running_task_count || 0) > 0"
                           class="host-workspace-badge running"