Preserve Assistant navigation state

Termind.xcodeproj/project.pbxproj

@@ -418,7 +418,7 @@
 					"@executable_path/../Frameworks",
 				);
 				LM_SKIP_METADATA_EXTRACTION = YES;
-				MARKETING_VERSION = 0.1.1;
+				MARKETING_VERSION = 0.1.2;
 				PRODUCT_BUNDLE_IDENTIFIER = com.akinokaede.termind;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_EMIT_LOC_STRINGS = YES;
@@ -449,7 +449,7 @@
 					"@executable_path/../Frameworks",
 				);
 				LM_SKIP_METADATA_EXTRACTION = YES;
-				MARKETING_VERSION = 0.1.1;
+				MARKETING_VERSION = 0.1.2;
 				PRODUCT_BUNDLE_IDENTIFIER = com.akinokaede.termind;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_EMIT_LOC_STRINGS = YES;

Termind/App/TermindCommands.swift

@@ -39,7 +39,7 @@ struct TermindCommands: Commands {
                 app.connect(in: window)
             }
             .keyboardShortcut("t")
-            Button("New Chat") { window?.openAssistant() }
+            Button("New Chat") { window?.openNewAssistantChat() }
                 .keyboardShortcut("t", modifiers: [.command, .option])
 
             Divider()

Termind/Application/Commands/AppCommandRegistry.swift

@@ -59,7 +59,7 @@ final class AppCommandRegistry {
             guard let host = app.hostLibrary.host(id) else { return }
             app.open(host, as: target, in: window)
         case .newChat:
-            window.openAssistant()
+            window.openNewAssistantChat()
         case .newHost:
             window.openHostEditor(host: nil)
         case .showAssistant:

Termind/Features/Assistant/AssistantView.swift

@@ -11,7 +11,7 @@ struct AssistantSidebarView: View {
             Divider()
             HStack(spacing: Metrics.Space.s) {
                 Button {
-                    window.openAssistant()
+                    window.openNewAssistantChat()
                 } label: {
                     Label("New Chat", systemImage: "plus.bubble")
                         .frame(
@@ -532,7 +532,7 @@ struct AssistantView: View {
         } else if let conversation = window.assistantLibrary.selectedConversation {
             ConversationView(
                 conversation: conversation,
-                onNewChat: { window.selectAssistant() }
+                onNewChat: { window.openNewAssistantChat() }
             )
                 .background(.background)
         } else {

Termind/Features/Tabs/TabBarView.swift

@@ -368,7 +368,7 @@ struct TabBarView: View {
             // Same order as the File menu, so the two lists of the same four
             // verbs cannot be read as two different lists.
             Button("Connect") { app.connect(in: window) }
-            Button("New Chat") { window.openAssistant() }
+            Button("New Chat") { window.openNewAssistantChat() }
             Button("New Host") { window.openHostEditor(host: nil) }
 
             let recents = app.hostLibrary.recents(limit: 5)

Termind/Features/Tabs/TabContentView.swift

@@ -765,7 +765,7 @@ struct WelcomeView: View {
         HStack(spacing: Metrics.Space.l) {
             Button("Connect") { app.connect(in: window) }
             Button("Batch Startup") { app.batchStartup(in: window) }
-            Button("New Chat") { window.openAssistant() }
+            Button("New Chat") { window.openNewAssistantChat() }
         }
     }
 

Termind/Features/Tabs/WindowModel.swift

@@ -393,13 +393,15 @@ final class WindowModel {
         selectedTopLevelTab = .vault
     }
 
-    func selectAssistant(_ id: ConversationModel.ID? = nil) {
+    /// Enters the Assistant without changing its in-memory navigation state:
+    /// the current conversation, New Chat, and Archive are all left untouched.
+    func selectAssistant() {
+        selectedTopLevelTab = .assistant
+    }
+
+    func selectAssistant(_ id: ConversationModel.ID) {
         isAssistantArchivePresented = false
-        if let id {
-            assistantLibrary.select(id)
-        } else {
-            assistantLibrary.selectNewConversation()
-        }
+        assistantLibrary.select(id)
         selectedTopLevelTab = .assistant
     }
 
@@ -652,7 +654,7 @@ final class WindowModel {
     }
 
     @discardableResult
-    func openAssistant() -> ConversationModel {
+    func openNewAssistantChat() -> ConversationModel {
         isAssistantArchivePresented = false
         let conversation = assistantLibrary.selectNewConversation()
         selectedTopLevelTab = .assistant

TermindTests/WindowStateTests.swift

@@ -202,7 +202,49 @@ struct WindowStateTests {
     }
 
     @Test
-    func assistantDefaultsToNewChatEvenWhenHistoryExists() {
+    func enteringAssistantKeepsTheVolatileConversationSelection() {
+        let conversation = ConversationModel()
+        let library = AssistantLibraryModel(store: AssistantConversationStore(
+            conversations: [conversation]
+        ))
+        let window = WindowModel(assistantLibrary: library)
+
+        window.selectAssistant(conversation.id)
+        window.selectVault()
+        window.selectAssistant()
+
+        #expect(window.selectedTopLevelTab == .assistant)
+        #expect(window.assistantLibrary.selectedConversation === conversation)
+
+        let draft = window.openNewAssistantChat()
+        #expect(window.assistantLibrary.selectedConversation == nil)
+        #expect(draft === window.assistantLibrary.draftConversation)
+
+        window.selectVault()
+        window.selectAssistant()
+        #expect(window.assistantLibrary.selectedConversation == nil)
+        #expect(draft === window.assistantLibrary.draftConversation)
+    }
+
+    @Test
+    func enteringAssistantKeepsTheVolatileArchiveDestination() {
+        let conversation = ConversationModel()
+        let library = AssistantLibraryModel(store: AssistantConversationStore(
+            conversations: [conversation]
+        ))
+        let window = WindowModel(assistantLibrary: library)
+
+        window.selectAssistant(conversation.id)
+        window.showAssistantArchive()
+        window.selectVault()
+        window.selectAssistant()
+
+        #expect(window.isAssistantArchivePresented)
+        #expect(window.assistantLibrary.selectedConversation === conversation)
+    }
+
+    @Test
+    func assistantStartsOnNewChatWhenNoVolatileSelectionExists() {
         let previousID = UUID()
         let library = AssistantLibraryModel()
         library.restore([
@@ -225,7 +267,7 @@ struct WindowStateTests {
     @Test
     func newChatJoinsHistoryOnlyAfterItsFirstSend() {
         let window = WindowModel()
-        let draft = window.openAssistant()
+        let draft = window.openNewAssistantChat()
 
         #expect(window.assistantLibrary.selectedConversation == nil)
         #expect(window.assistantLibrary.conversations.isEmpty)