fix: defer plugin mode changes past view updates

macOS segmented Picker writes its binding within a SwiftUI update.
Defer the draft mutation to a main actor task to prevent synchronous
Published notifications during that update.

ShadowsocksX-NG2/App/ServerPluginSection.swift

@@ -103,7 +103,7 @@ struct ServerPluginSection: View {
 }
 
 /// 查看模式切换（参数列表 ⇄ 原始文本）；被未完成行拒绝时回弹到当前模式。
-private struct PluginOptionsModePicker: View {
+struct PluginOptionsModePicker: View {
   @ObservedObject var draft: PluginOptionsDraft
   @State private var displayedMode = PluginOptionsDraft.Mode.table
 
@@ -123,9 +123,14 @@ private struct PluginOptionsModePicker: View {
     Binding(
       get: { displayedMode },
       set: { requested in
-        let succeeded =
-          requested == .rawText ? draft.switchToRawText() : draft.switchToTable()
-        displayedMode = succeeded ? requested : draft.mode
+        displayedMode = requested
+        // macOS 分段 Picker 在 SwiftUI 更新事务内调用绑定 setter；草稿的
+        // @Published 更新须离开该事务，避免向观察视图同步发布变更。
+        Task { @MainActor in
+          let succeeded =
+            requested == .rawText ? draft.switchToRawText() : draft.switchToTable()
+          displayedMode = succeeded ? requested : draft.mode
+        }
       })
   }
 }

ShadowsocksX-NG2/Tests/PluginOptionsModePickerTests.swift

@@ -0,0 +1,66 @@
+import AppKit
+import Combine
+import SwiftUI
+import Testing
+
+@testable import ShadowsocksX_NG2
+
+@MainActor
+struct PluginOptionsModePickerTests {
+  @Test
+  func nativePickerDefersDraftPublicationUntilAfterItsAction() async throws {
+    let draft = PluginOptionsDraft()
+    draft.load("tls;host=example.com;path=/ws;")
+    let host = NSHostingView(rootView: PluginOptionsModePicker(draft: draft))
+    host.frame = NSRect(x: 0, y: 0, width: 320, height: 60)
+    host.layoutSubtreeIfNeeded()
+    let picker = try #require(Self.segmentedControl(in: host))
+    var publications = 0
+    let observation = draft.objectWillChange.sink { publications += 1 }
+    defer { observation.cancel() }
+
+    // 原生 macOS Picker 的 action 在 SwiftUI 更新事务内写入绑定。
+    // 此时同步发布 ObservableObject 变更会触发运行时警告。
+    picker.selectedSegment = 1
+    picker.sendAction(picker.action, to: picker.target)
+    #expect(publications == 0)
+    #expect(draft.mode == .table)
+
+    await Task { @MainActor in }.value
+    #expect(draft.mode == .rawText)
+    #expect(draft.rawText == "tls;host=example.com;path=/ws;")
+    #expect(publications > 0)
+
+    publications = 0
+    picker.selectedSegment = 0
+    picker.sendAction(picker.action, to: picker.target)
+    #expect(publications == 0)
+    await Task { @MainActor in }.value
+    #expect(draft.mode == .table)
+    #expect(draft.composedString == "tls;host=example.com;path=/ws;")
+  }
+
+  @Test
+  func nativePickerKeepsTableModeWhenARowIsUnfinished() async throws {
+    let draft = PluginOptionsDraft()
+    draft.load("host=example.com")
+    draft.updateValue("unfinished", of: draft.quickAddRowID)
+    let host = NSHostingView(rootView: PluginOptionsModePicker(draft: draft))
+    host.frame = NSRect(x: 0, y: 0, width: 320, height: 60)
+    host.layoutSubtreeIfNeeded()
+    let picker = try #require(Self.segmentedControl(in: host))
+
+    picker.selectedSegment = 1
+    picker.sendAction(picker.action, to: picker.target)
+    await Task { @MainActor in }.value
+    host.layoutSubtreeIfNeeded()
+    #expect(draft.mode == .table)
+    #expect(draft.hasUnfinishedRows)
+    #expect(picker.selectedSegment == 0)
+  }
+
+  private static func segmentedControl(in view: NSView) -> NSSegmentedControl? {
+    if let control = view as? NSSegmentedControl { return control }
+    return view.subviews.lazy.compactMap { segmentedControl(in: $0) }.first
+  }
+}