Fix SFTP table AttributeGraph crash

Termind/Features/SFTP/SFTPBrowserView.swift

@@ -242,7 +242,13 @@ struct SFTPBrowserView: View {
 
     @ViewBuilder
     private var browserContent: some View {
-        Group {
+        // Keep the AppKit-backed Table mounted while its rows, selection, and
+        // connection state change. Removing it during an outline-view update
+        // leaves orphan NSTableRowViews whose AttributeGraph subgraph has
+        // already been dismantled ("precondition failure: no subgraph").
+        ZStack {
+            fileTable
+
             if sftpSession.status == .disconnected, !sftpSession.connectionJourney.isPresented {
                 VStack(spacing: Metrics.Space.l) {
                     Image(systemName: "folder.badge.questionmark")
@@ -252,12 +258,13 @@ struct SFTPBrowserView: View {
                         .buttonStyle(.borderedProminent)
                 }
                 .frame(maxWidth: .infinity, maxHeight: .infinity)
+                .background(.background)
             } else if sftpSession.files.isEmpty, sftpSession.isLoading {
                 centeredState("Loading", symbol: "arrow.triangle.2.circlepath", progress: true)
+                    .background(.background)
             } else if sftpSession.files.isEmpty, sftpSession.status == .connected {
                 centeredState("This folder is empty", symbol: "folder", progress: false)
-            } else {
-                fileTable
+                    .background(.background)
             }
         }
         .onDrop(

Termind/Features/SFTP/SFTPSessionModel.swift

@@ -1,5 +1,27 @@
 import Foundation
 
+/// State consumed by SwiftUI's macOS `Table` must change as one value.
+///
+/// `Table` is backed by `NSOutlineView`. Publishing its rows, filter, and
+/// selection independently can briefly leave the outline view selecting an ID
+/// whose row has already become an orphan. On macOS that can make SwiftUI ask
+/// AttributeGraph for the orphan row's dismantled subgraph and trap with
+/// "precondition failure: no subgraph".
+private struct SFTPDirectoryPresentation {
+    var files: [RemoteFile] = []
+    var selection: Set<RemoteFile.ID> = []
+    var query = ""
+
+    var filteredFiles: [RemoteFile] {
+        guard !query.isEmpty else { return files }
+        return files.filter { $0.name.localizedCaseInsensitiveContains(query) }
+    }
+
+    mutating func reconcileSelection() {
+        selection.formIntersection(Set(filteredFiles.map(\.id)))
+    }
+}
+
 @Observable
 final class SFTPSessionModel: Identifiable {
     struct PreparedJob {
@@ -46,9 +68,26 @@ final class SFTPSessionModel: Identifiable {
     var pathText: String
     private(set) var backHistory: [String] = []
     private(set) var forwardHistory: [String] = []
-    var selection: Set<RemoteFile.ID> = []
-    var query = ""
-    private(set) var files: [RemoteFile] = []
+    private var directoryPresentation = SFTPDirectoryPresentation()
+    var selection: Set<RemoteFile.ID> {
+        get { directoryPresentation.selection }
+        set {
+            var presentation = directoryPresentation
+            presentation.selection = newValue
+            presentation.reconcileSelection()
+            directoryPresentation = presentation
+        }
+    }
+    var query: String {
+        get { directoryPresentation.query }
+        set {
+            var presentation = directoryPresentation
+            presentation.query = newValue
+            presentation.reconcileSelection()
+            directoryPresentation = presentation
+        }
+    }
+    var files: [RemoteFile] { directoryPresentation.files }
     private(set) var status: ConnectionStatus = .disconnected {
         didSet {
             statusStore?.setConnectionStatus(status, connectionID: id, hostID: hostID)
@@ -115,8 +154,7 @@ final class SFTPSessionModel: Identifiable {
         pendingRemoteCopyBatch?.conflictCount ?? pendingBatch?.conflictCount ?? 0
     }
     var filteredFiles: [RemoteFile] {
-        guard !query.isEmpty else { return files }
-        return files.filter { $0.name.localizedCaseInsensitiveContains(query) }
+        directoryPresentation.filteredFiles
     }
     var selectedFiles: [RemoteFile] {
         files.filter { selection.contains($0.id) }
@@ -318,7 +356,7 @@ final class SFTPSessionModel: Identifiable {
         usesEphemeralCredentials = false
         status = .disconnected
         connectionJourney.hide()
-        files = []
+        replaceDirectoryContents(with: [])
         Task { [id] in
             await transferCoordinator?.cancelTransfers(usingBorrowedConnection: id)
             await client?.disconnect()
@@ -502,8 +540,7 @@ final class SFTPSessionModel: Identifiable {
         do {
             let snapshot = try await client.listDirectory(at: requestedPath)
             guard status == .connected, path == requestedPath else { return }
-            files = snapshot
-            selection.formIntersection(Set(snapshot.map(\.id)))
+            replaceDirectoryContents(with: snapshot)
             hint =
                 snapshot.count == 1
                 ? String(localized: "1 item") : String(localized: "\(snapshot.count) items")
@@ -540,6 +577,15 @@ final class SFTPSessionModel: Identifiable {
         }
     }
 
+    /// Publishes rows and their valid selection in one observable mutation so
+    /// SwiftUI never receives an intermediate table state.
+    private func replaceDirectoryContents(with files: [RemoteFile]) {
+        var presentation = directoryPresentation
+        presentation.files = files
+        presentation.reconcileSelection()
+        directoryPresentation = presentation
+    }
+
     func scheduleSilentRefresh(after delay: Duration = .milliseconds(250)) {
         uploadRefreshTask?.cancel()
         uploadRefreshTask = Task { [weak self] in

TermindTests/SFTPFeatureTests.swift

@@ -173,6 +173,44 @@ struct SFTPFeatureTests {
         #expect(sftpSession.files == [updated])
     }
 
+    @Test
+    func directoryRefreshReconcilesRowsAndSelection() async {
+        let retained = remoteFile(path: "/home/retained.txt", kind: .file)
+        let removed = remoteFile(path: "/home/removed.txt", kind: .file)
+        let client = SnapshotSFTPClient(
+            responses: [.success([retained, removed]), .success([retained])]
+        )
+        let sftpSession = SFTPSessionModel(
+            hostID: UUID(), initialPath: "/home", client: client,
+            configuration: testConfiguration
+        )
+
+        await sftpSession.reload(silently: true)
+        sftpSession.selection = [retained.id, removed.id]
+        await sftpSession.reload(silently: true)
+
+        #expect(sftpSession.files == [retained])
+        #expect(sftpSession.selection == [retained.id])
+    }
+
+    @Test
+    func filteringPrunesSelectionThatIsNotRepresentedByTheTable() async {
+        let visible = remoteFile(path: "/home/visible.txt", kind: .file)
+        let hidden = remoteFile(path: "/home/hidden.log", kind: .file)
+        let client = SnapshotSFTPClient(responses: [.success([visible, hidden])])
+        let sftpSession = SFTPSessionModel(
+            hostID: UUID(), initialPath: "/home", client: client,
+            configuration: testConfiguration
+        )
+
+        await sftpSession.reload(silently: true)
+        sftpSession.selection = [hidden.id]
+        sftpSession.query = "visible"
+
+        #expect(sftpSession.filteredFiles == [visible])
+        #expect(sftpSession.selection.isEmpty)
+    }
+
     @Test
     func automaticRefreshRepeatsUntilDisconnect() async {
         let client = SnapshotSFTPClient(responses: [.success([])])