Fix Assistant sidebar navigation round-trip

Termind/Features/Sidebar/WindowSidebarView.swift

@@ -70,8 +70,8 @@ struct WindowSidebarView: View {
         let isEnabled = window.isSidebarModeEnabled(mode)
 
         return Button {
-            guard mode == .navigation || isEnabled else { return }
-            window.sidebarMode = mode
+            guard isEnabled else { return }
+            window.activateSidebarMode(mode)
         } label: {
             Group {
                 if #available(macOS 26.0, *), usesSystemGlass, isSelected {

Termind/Features/Workspaces/WindowModel.swift

@@ -20,7 +20,17 @@ final class WindowModel {
     }
     /// The top-level shell has two pinned entries followed by dynamic SSH/SFTP
     /// Workspaces. This is the single source of truth for workspace selection.
-    var selectedDestination: WindowDestination = .vault
+    var selectedDestination: WindowDestination = .vault {
+        didSet {
+            if selectedDestination != .assistant {
+                assistantReturnDestination = selectedDestination
+            }
+        }
+    }
+    /// Where Navigator returns after the Assistant temporarily replaces the
+    /// detail surface. Assistant has no row inside the Navigator that could
+    /// retain the previous selection for us.
+    private var assistantReturnDestination: WindowDestination = .vault
     var vaultDestination: VaultDestination = .welcome
     var vaultWorkRoute: VaultWorkRoute?
     let assistantLibrary: AssistantLibraryModel
@@ -158,6 +168,48 @@ final class WindowModel {
         sidebar.reconcileMode()
     }
 
+    /// Applies a Sidebar mode chosen by the user, including the two mode-rail
+    /// buttons that also act as top-level navigation affordances.
+    ///
+    /// Direct `sidebarMode` assignment deliberately remains presentation-only
+    /// for restoration, screenshots, and other programmatic configuration.
+    func activateSidebarMode(_ mode: SidebarMode) {
+        guard sidebar.isModeEnabled(mode) else { return }
+        sidebarMode = mode
+
+        switch mode {
+        case .assistant:
+            // Inside a Workspace this is its compact, context-aware Assistant.
+            // Everywhere else the same control opens the full Assistant route.
+            if selectedWorkspace == nil {
+                selectAssistant()
+            }
+        case .navigation:
+            if selectedDestination == .assistant {
+                restoreAssistantReturnDestination()
+            }
+        case .snippets, .history:
+            break
+        }
+    }
+
+    private func restoreAssistantReturnDestination() {
+        switch assistantReturnDestination {
+        case .workspace(let id):
+            if workspaces.contains(where: { $0.id == id }) {
+                select(id)
+            } else {
+                selectVault()
+            }
+        case .vault:
+            selectVault()
+        case .assistant:
+            // Defensive only: the remembered destination is updated exclusively
+            // from non-Assistant routes.
+            selectVault()
+        }
+    }
+
     /// Opens the shared column and selects the current Workspace's assistant.
     /// Repeating the command is intentionally idempotent; hiding the column is
     /// the native Toggle Sidebar command's job.
@@ -195,6 +247,8 @@ final class WindowModel {
         self.vaultDestination = vaultDestination
         self.assistantLibrary = assistantLibrary
         selectedDestination = workspaces.first.map { .workspace($0.id) } ?? .vault
+        // Property observers do not run while an instance is being initialized.
+        assistantReturnDestination = selectedDestination
         for workspace in workspaces {
             workspace.lifecycleRouter = self
         }

Termind/Resources/Localizable.xcstrings

@@ -2365,6 +2365,10 @@
         }
       }
     },
+    "Choose" : {
+      "comment" : "A button that opens a file picker to choose a private key.",
+      "isCommentAutoGenerated" : true
+    },
     "Choose a private key or OpenSSH user certificate file." : {
       "localizations" : {
         "zh-Hans" : {
@@ -2386,6 +2390,7 @@
       }
     },
     "Choose File…" : {
+      "extractionState" : "stale",
       "localizations" : {
         "zh-Hans" : {
           "stringUnit" : {
@@ -4197,16 +4202,6 @@
         }
       }
     },
-    "Files and images" : {
-      "localizations" : {
-        "zh-Hans" : {
-          "stringUnit" : {
-            "state" : "translated",
-            "value" : "文件与图片"
-          }
-        }
-      }
-    },
     "Dropped image" : {
       "localizations" : {
         "zh-Hans" : {
@@ -4948,6 +4943,16 @@
         }
       }
     },
+    "Files and images" : {
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "文件与图片"
+          }
+        }
+      }
+    },
     "Files are identical" : {
       "localizations" : {
         "zh-Hans" : {
@@ -5842,16 +5847,6 @@
         }
       }
     },
-    "Import Private Key" : {
-      "localizations" : {
-        "zh-Hans" : {
-          "stringUnit" : {
-            "state" : "translated",
-            "value" : "导入私钥"
-          }
-        }
-      }
-    },
     "Import or generate a key, then create an identity with a username. Private keys stay in the Keychain." : {
       "localizations" : {
         "zh-Hans" : {
@@ -5862,6 +5857,16 @@
         }
       }
     },
+    "Import Private Key" : {
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "导入私钥"
+          }
+        }
+      }
+    },
     "In Current Workspace" : {
       "localizations" : {
         "zh-Hans" : {
@@ -14535,4 +14540,4 @@
     }
   },
   "version" : "1.2"
-}
+}

TermindTests/WindowStateTests.swift

@@ -321,13 +321,88 @@ struct WindowStateTests {
     func selectingAssistantDoesNotCreateAConversation() {
         let window = WindowModel()
 
-        window.selectAssistant()
+        window.activateSidebarMode(.assistant)
 
         #expect(window.selectedDestination == .assistant)
         #expect(window.assistantLibrary.conversations.isEmpty)
         #expect(window.assistantLibrary.selectedConversation == nil)
     }
 
+    @Test
+    func assistantAndNavigatorModeRailRoundTripsToThePreviousVaultRoute() {
+        let conversation = ConversationModel()
+        let library = AssistantLibraryModel(store: AssistantConversationStore(
+            conversations: [conversation]
+        ))
+        let window = WindowModel(assistantLibrary: library)
+        window.selectAssistant(conversation.id)
+        window.openVaultWork(.hostEditor(nil), on: .hosts)
+
+        // The Assistant mode can already be selected after navigation elsewhere;
+        // pressing its selected button must still activate the Assistant route.
+        window.sidebarMode = .assistant
+        window.activateSidebarMode(.assistant)
+
+        #expect(window.selectedDestination == .assistant)
+        #expect(window.assistantLibrary.selectedConversation === conversation)
+
+        window.activateSidebarMode(.navigation)
+
+        #expect(window.selectedDestination == .vault)
+        #expect(window.vaultDestination == .hosts)
+        #expect(window.vaultWorkRoute == .hostEditor(nil))
+    }
+
+    @Test
+    func assistantModeRailStaysCompactInWorkspaceAndNavigatorReturnsThereFromFullScreen() {
+        let workspace = Workspace.sshSession(
+            host: Host(name: "Server", host: "server.example")
+        )
+        let window = WindowModel(workspaces: [workspace])
+
+        window.activateSidebarMode(.assistant)
+
+        #expect(window.sidebarMode == .assistant)
+        #expect(window.selectedDestination == .workspace(workspace.id))
+
+        let conversation = window.assistantLibrary.createConversation()
+        window.openAssistantFullScreen(conversation.id)
+        window.activateSidebarMode(.navigation)
+
+        #expect(window.sidebarMode == .navigation)
+        #expect(window.selectedDestination == .workspace(workspace.id))
+    }
+
+    @Test
+    func navigatorFallsBackToVaultWhenTheAssistantReturnWorkspaceWasClosed() {
+        let workspace = Workspace.sshSession(
+            host: Host(name: "Server", host: "server.example")
+        )
+        let window = WindowModel(workspaces: [workspace])
+        window.openAssistantFullScreen()
+
+        window.close(workspace.id)
+        window.activateSidebarMode(.navigation)
+
+        #expect(window.workspaces.isEmpty)
+        #expect(window.selectedDestination == .vault)
+    }
+
+    @Test
+    func nonNavigationToolModesAndDirectModeAssignmentDoNotNavigate() {
+        let window = WindowModel()
+        window.openPage(.hosts)
+
+        window.sidebarMode = .assistant
+        #expect(window.selectedDestination == .vault)
+
+        window.activateSidebarMode(.snippets)
+        #expect(window.selectedDestination == .vault)
+
+        window.activateSidebarMode(.history)
+        #expect(window.selectedDestination == .vault)
+    }
+
     @Test
     func enteringAssistantKeepsTheVolatileConversationSelection() {
         let conversation = ConversationModel()
@@ -338,7 +413,7 @@ struct WindowStateTests {
 
         window.selectAssistant(conversation.id)
         window.selectVault()
-        window.selectAssistant()
+        window.activateSidebarMode(.assistant)
 
         #expect(window.selectedDestination == .assistant)
         #expect(window.assistantLibrary.selectedConversation === conversation)
@@ -348,7 +423,7 @@ struct WindowStateTests {
         #expect(draft === window.assistantLibrary.draftConversation)
 
         window.selectVault()
-        window.selectAssistant()
+        window.activateSidebarMode(.assistant)
         #expect(window.assistantLibrary.selectedConversation == nil)
         #expect(draft === window.assistantLibrary.draftConversation)
     }
@@ -364,7 +439,7 @@ struct WindowStateTests {
         window.selectAssistant(conversation.id)
         window.showAssistantArchive()
         window.selectVault()
-        window.selectAssistant()
+        window.activateSidebarMode(.assistant)
 
         #expect(window.isAssistantArchivePresented)
         #expect(window.assistantLibrary.selectedConversation === conversation)