fix(app): keep server tree collapse state across destinations

Both server trees held collapse state inside the destination
subtree — ServersView relied on OutlineGroup's built-in expansion
state and the home target tree kept a local @State set — so every
destination switch destroyed it. Hoist a shared
CatalogExpansionState to the composition root; the servers sidebar
and the home target tree now read and write one collapse set.

ServersView replaces OutlineGroup with a manual collapse tree
(flattened visible rows, .tag keeps List selection), trading away
OutlineGroup's arrow-key expand/collapse. MainApp extracts
makeRuntimeController to stay within the function-body lint budget.

ShadowsocksX-NG2/App/CatalogExpansionState.swift

@@ -0,0 +1,22 @@
+import Combine
+
+/// 目录树折叠状态（纯窗口呈现状态）：组合根持有的长寿命对象。destination 切换
+/// 会销毁分区子树里的 `@State`，折叠状态因此必须活在视图层级之外；服务器分区
+/// 侧栏与首页目标树共用同一实例，一处收起、两处互见。语义=收起的分组身份集合，
+/// 缺省全部展开；不落盘，进程重启回全展开基线。
+@MainActor
+final class CatalogExpansionState: ObservableObject {
+  @Published private(set) var collapsedGroupIDs: Set<NodeID> = []
+
+  func isCollapsed(_ id: NodeID) -> Bool {
+    collapsedGroupIDs.contains(id)
+  }
+
+  func toggleCollapsed(_ id: NodeID) {
+    if collapsedGroupIDs.contains(id) {
+      collapsedGroupIDs.remove(id)
+    } else {
+      collapsedGroupIDs.insert(id)
+    }
+  }
+}

ShadowsocksX-NG2/App/HomeView+Cards.swift

@@ -4,12 +4,11 @@ import SwiftUI
 struct TargetTreeCard: View {
   @ObservedObject var workflow: CatalogWorkflow
   @ObservedObject var control: ProxyControlWorkflow
+  /// 分组折叠状态：组合根持有的共享对象，与服务器分区侧栏同源，跨分区切换存续。
+  @ObservedObject var expansion: CatalogExpansionState
   let onManageServers: () -> Void
   let errors: ErrorAlertPresenter
 
-  /// 收起状态的目标分组（默认全部展开）。
-  @State private var collapsedGroups: Set<NodeID> = []
-
   var body: some View {
     HomeCard(
       title: "当前服务器",
@@ -45,8 +44,8 @@ struct TargetTreeCard: View {
           TargetGroupSection(
             group: group,
             activeTargetID: control.snapshot.activeTarget?.id,
-            isCollapsed: isCollapsed(group.id),
-            onToggle: { toggleCollapsed(group.id) },
+            isCollapsed: expansion.isCollapsed(group.id),
+            onToggle: { expansion.toggleCollapsed(group.id) },
             onActivate: activate)
         }
         ForEach(rootServers) { server in
@@ -69,18 +68,6 @@ struct TargetTreeCard: View {
     }
   }
 
-  private func toggleCollapsed(_ id: NodeID) {
-    if isCollapsed(id) {
-      collapsedGroups.remove(id)
-    } else {
-      collapsedGroups.insert(id)
-    }
-  }
-
-  private func isCollapsed(_ id: NodeID) -> Bool {
-    collapsedGroups.contains(id)
-  }
-
   /// 有服务器叶子的分组（递归收集；每组只呈现直属服务器叶子）。
   private var targetGroups: [TargetGroupInfo] {
     var groups: [TargetGroupInfo] = []

ShadowsocksX-NG2/App/HomeView.swift

@@ -7,6 +7,7 @@ import SwiftUI
 struct HomeView: View {
   @ObservedObject var workflow: CatalogWorkflow
   @ObservedObject var control: ProxyControlWorkflow
+  let expansion: CatalogExpansionState
   let clipboard: any TextClipboard
   let onManageServers: () -> Void
   let errors: ErrorAlertPresenter
@@ -19,6 +20,7 @@ struct HomeView: View {
           TargetTreeCard(
             workflow: workflow,
             control: control,
+            expansion: expansion,
             onManageServers: onManageServers,
             errors: errors)
         }

ShadowsocksX-NG2/App/MainApp.swift

@@ -104,6 +104,7 @@ private struct AppComposition {
   let diagnosticsWorkflow: DiagnosticsWorkflow
   let workspaceRoute: WorkspaceRoute
   let silentLaunch: SilentLaunchController
+  let expansion: CatalogExpansionState
   let textClipboard: any TextClipboard
   let workspaceContent: MainWindowView
 
@@ -115,16 +116,8 @@ private struct AppComposition {
     // access to this same in-process source.
     let catalogBootstrap = CatalogCommitCoordinator.bootstrap(
       fileStore: dependencies.catalogFileStore)
-    let controller = ProxyRuntimeController(
-      catalogSnapshotReader: catalogBootstrap.catalogSnapshotReader,
-      activationFileStore: dependencies.activationFileStore,
-      runtimeFileStore: dependencies.runtimeFileStore,
-      credentials: dependencies.credentials,
-      listenRestore: dependencies.listenRestore,
-      settingsStore: dependencies.settingsStore,
-      settingsRestore: dependencies.settingsRestore,
-      agent: dependencies.launchAgent,
-      systemProxyNetworkChangeMonitor: SystemProxyNetworkChangeMonitor())
+    let controller = makeRuntimeController(
+      dependencies: dependencies, bootstrap: catalogBootstrap)
     let loginController = LaunchAtLoginController(service: dependencies.loginService)
     let catalogWorkflow = makeCatalogWorkflow(
       dependencies: dependencies,
@@ -145,6 +138,7 @@ private struct AppComposition {
       catalogFacts: { catalogWorkflow.diagnosticCatalogFacts })
     let workspaceRoute = WorkspaceRoute()
     let silentLaunch = SilentLaunchController(store: dependencies.silentLaunchStore)
+    let expansion = CatalogExpansionState()
     let workspaceContent = MainWindowView(
       route: workspaceRoute,
       workflow: catalogWorkflow,
@@ -154,6 +148,7 @@ private struct AppComposition {
       settingsWorkflow: settingsWorkflow,
       loginController: loginController,
       silentLaunch: silentLaunch,
+      expansion: expansion,
       clipboard: textClipboard,
       diagnosticReportExporter: dependencies.diagnosticReportExporter,
       configurationGroupFileExporter: dependencies.configurationGroupFileExporter)
@@ -166,10 +161,29 @@ private struct AppComposition {
       diagnosticsWorkflow: diagnosticsWorkflow,
       workspaceRoute: workspaceRoute,
       silentLaunch: silentLaunch,
+      expansion: expansion,
       textClipboard: textClipboard,
       workspaceContent: workspaceContent)
   }
 
+  /// 运行时控制器接线：读侧接目录提交协调器快照，写侧接各持久化 seam 与
+  /// 系统服务适配器。
+  private static func makeRuntimeController(
+    dependencies: ApplicationDependencies,
+    bootstrap: CatalogCommitBootstrap
+  ) -> ProxyRuntimeController {
+    ProxyRuntimeController(
+      catalogSnapshotReader: bootstrap.catalogSnapshotReader,
+      activationFileStore: dependencies.activationFileStore,
+      runtimeFileStore: dependencies.runtimeFileStore,
+      credentials: dependencies.credentials,
+      listenRestore: dependencies.listenRestore,
+      settingsStore: dependencies.settingsStore,
+      settingsRestore: dependencies.settingsRestore,
+      agent: dependencies.launchAgent,
+      systemProxyNetworkChangeMonitor: SystemProxyNetworkChangeMonitor())
+  }
+
   /// 目录工作流接线（issue #40/#41/#49）：提交协调器与生产运行时适配器在此
   /// 一次性装配；Legacy 导入后的 2.0 运行时边界同为一次性注入。
   private static func makeCatalogWorkflow(

ShadowsocksX-NG2/App/MainWindowView.swift

@@ -35,6 +35,9 @@ struct MainWindowView: View {
   @ObservedObject var settingsWorkflow: SettingsWorkflow
   @ObservedObject var loginController: LaunchAtLoginController
   @ObservedObject var silentLaunch: SilentLaunchController
+  /// 目录树折叠状态：组合根持有的长寿命对象，跨 destination 切换存续；服务器
+  /// 侧栏与首页目标树共用（见 CatalogExpansionState）。
+  @ObservedObject var expansion: CatalogExpansionState
   let clipboard: any TextClipboard
   let diagnosticReportExporter: any DiagnosticReportExporter
   let configurationGroupFileExporter: any ConfigurationGroupFileExporter
@@ -183,6 +186,7 @@ struct MainWindowView: View {
       WorkspaceHomeView(
         workflow: workflow,
         control: control,
+        expansion: expansion,
         clipboard: clipboard,
         onManageServers: { route.navigate(to: .servers) })
     case .servers:
@@ -190,6 +194,7 @@ struct MainWindowView: View {
         workflow: workflow,
         proxyController: proxyController,
         selection: $selection,
+        expansion: expansion,
         clipboard: clipboard,
         configurationGroupFileExporter: configurationGroupFileExporter)
     case .subscriptions:

ShadowsocksX-NG2/App/ServersView.swift

@@ -11,6 +11,9 @@ struct ServersView: View {
   /// 运行时事实来源：活动目标标记；激活命令经 `workflow.activate`。
   @ObservedObject var proxyController: ProxyRuntimeController
   @Binding var selection: NodeID?
+  /// 分组折叠状态：组合根持有的共享对象（与首页目标树同源），跨 destination
+  /// 切换存续；OutlineGroup 的内建展开态会随分区切换丢失，侧栏因此自管折叠。
+  @ObservedObject var expansion: CatalogExpansionState
   let clipboard: any TextClipboard
   let configurationGroupFileExporter: any ConfigurationGroupFileExporter
 
@@ -96,33 +99,8 @@ struct ServersView: View {
 
   private var serverSidebar: some View {
     List(selection: $selection) {
-      OutlineGroup(workflow.tree.roots, children: \.children) { node in
-        SidebarRow(
-          node: node,
-          workflow: workflow,
-          activeTargetID: proxyController.activeTargetID,
-          errors: errors,
-          onRename: { id in
-            renameTarget = id
-            renameText = workflow.displayName(for: id)
-          },
-          onNewGroup: { parent in
-            presentNewGroup(in: parent)
-          },
-          onMove: { moveTarget = $0 },
-          onDelete: { deleteTarget = $0 },
-          onExport: exportConfigurationGroup
-        )
-        .onDrag {
-          guard let payload = workflow.dragPayload(for: node.id) else {
-            return NSItemProvider()
-          }
-          return NSItemProvider(object: payload as NSString)
-        }
-        .dropDestination(for: String.self) { payload, _ in
-          handleDrop(payload, onto: node.id)
-        } isTargeted: { _ in
-        }
+      ForEach(visibleRows) { row in
+        treeRow(row)
       }
     }
     .listStyle(.sidebar)
@@ -143,6 +121,81 @@ struct ServersView: View {
     .toolbar { toolbarContent }
   }
 
+  /// 折叠投影后的可见行（深度优先）：收起分组的子树不出现，其余保持目录序。
+  private var visibleRows: [CatalogTreeRow] {
+    var rows: [CatalogTreeRow] = []
+    func walk(_ nodes: [CatalogTreeNode], depth: Int) {
+      for node in nodes {
+        rows.append(CatalogTreeRow(node: node, depth: depth))
+        if node.isGroup, !expansion.isCollapsed(node.id) {
+          walk(node.childNodes, depth: depth + 1)
+        }
+      }
+    }
+    walk(workflow.tree.roots, depth: 0)
+    return rows
+  }
+
+  private func treeRow(_ row: CatalogTreeRow) -> some View {
+    let node = row.node
+    return HStack(spacing: 4) {
+      if node.isGroup {
+        if node.childNodes.isEmpty {
+          Color.clear.frame(width: 11, height: 11)
+        } else {
+          Button {
+            withAnimation { expansion.toggleCollapsed(node.id) }
+          } label: {
+            Image(systemName: "chevron.right")
+              .font(.caption2.weight(.semibold))
+              .foregroundStyle(.secondary)
+              .rotationEffect(.degrees(expansion.isCollapsed(node.id) ? 0 : 90))
+          }
+          .buttonStyle(.plain)
+          .help(expansion.isCollapsed(node.id) ? "展开" : "收起")
+        }
+      }
+      SidebarRow(
+        node: node,
+        workflow: workflow,
+        activeTargetID: proxyController.activeTargetID,
+        errors: errors,
+        onRename: { id in
+          renameTarget = id
+          renameText = workflow.displayName(for: id)
+        },
+        onNewGroup: { parent in
+          presentNewGroup(in: parent)
+        },
+        onMove: { moveTarget = $0 },
+        onDelete: { deleteTarget = $0 },
+        onExport: exportConfigurationGroup
+      )
+    }
+    .padding(.leading, leadingInset(for: row))
+    .tag(node.id)
+    .onDrag {
+      guard let payload = workflow.dragPayload(for: node.id) else {
+        return NSItemProvider()
+      }
+      return NSItemProvider(object: payload as NSString)
+    }
+    .dropDestination(for: String.self) { payload, _ in
+      handleDrop(payload, onto: node.id)
+    } isTargeted: { _ in
+    }
+  }
+
+  /// 层级缩进：分组行按深度缩进；叶子行额外让出箭头槽位与分组文本对齐。
+  private func leadingInset(for row: CatalogTreeRow) -> CGFloat {
+    let depthStep: CGFloat = 14
+    let chevronSlot: CGFloat = 15
+    if row.node.isGroup {
+      return CGFloat(row.depth) * depthStep
+    }
+    return CGFloat(row.depth) * depthStep + chevronSlot
+  }
+
   /// 删除结果 → selection invalidation（story 18）：仅清除失效选择，不自动
   /// 改选相邻节点。
   private func clearSelectionIfInvalidated(_ removed: Set<NodeID>) {
@@ -309,3 +362,11 @@ private struct MoveContext: Identifiable {
   let nodeID: NodeID
   var id: NodeID { nodeID }
 }
+
+/// 侧栏树的可见行投影：节点 + 呈现深度；身份即节点身份（折叠只影响可见集合，
+/// 不影响行身份与选中）。
+private struct CatalogTreeRow: Identifiable {
+  let node: CatalogTreeNode
+  let depth: Int
+  var id: NodeID { node.id }
+}

ShadowsocksX-NG2/App/WorkspaceDestinations.swift

@@ -6,6 +6,7 @@ import SwiftUI
 struct WorkspaceHomeView: View {
   @ObservedObject var workflow: CatalogWorkflow
   @ObservedObject var control: ProxyControlWorkflow
+  let expansion: CatalogExpansionState
   let clipboard: any TextClipboard
   let onManageServers: () -> Void
   @StateObject private var errors = ErrorAlertPresenter()
@@ -17,6 +18,7 @@ struct WorkspaceHomeView: View {
     HomeView(
       workflow: workflow,
       control: control,
+      expansion: expansion,
       clipboard: clipboard,
       onManageServers: onManageServers,
       errors: errors

ShadowsocksX-NG2/Tests/CatalogExpansionStateTests.swift

@@ -0,0 +1,43 @@
+import XCTest
+
+@testable import ShadowsocksX_NG2
+
+@MainActor
+final class CatalogExpansionStateTests: XCTestCase {
+  func testFreshStateIsFullyExpanded() {
+    let expansion = CatalogExpansionState()
+
+    XCTAssertTrue(expansion.collapsedGroupIDs.isEmpty)
+    XCTAssertFalse(expansion.isCollapsed(NodeID(rawValue: "g1")))
+  }
+
+  /// 切换语义：未收起 → 收起 → 再切换 → 展开（分区切换往返不重置的事实基础）。
+  func testToggleCollapsesThenReexpands() {
+    let expansion = CatalogExpansionState()
+    let id = NodeID(rawValue: "g1")
+
+    expansion.toggleCollapsed(id)
+    XCTAssertTrue(expansion.isCollapsed(id))
+
+    expansion.toggleCollapsed(id)
+    XCTAssertFalse(expansion.isCollapsed(id))
+  }
+
+  /// 两处服务器树（服务器侧栏/首页目标树）共用同一实例：同一分组身份在两处
+  /// 读到同一折叠事实，互不覆盖。
+  func testCollapseSetIsKeyedPerGroupID() {
+    let expansion = CatalogExpansionState()
+    let first = NodeID(rawValue: "g-first")
+    let second = NodeID(rawValue: "g-second")
+
+    expansion.toggleCollapsed(first)
+    expansion.toggleCollapsed(second)
+
+    XCTAssertEqual(expansion.collapsedGroupIDs, [first, second])
+
+    expansion.toggleCollapsed(first)
+    XCTAssertEqual(expansion.collapsedGroupIDs, [second])
+    XCTAssertFalse(expansion.isCollapsed(first))
+    XCTAssertTrue(expansion.isCollapsed(second))
+  }
+}