Make a vault the thing you create, and let a window set one aside

Everything a shared vault needs was already here and arranged the wrong way
round. A vault has to belong to a team, so creating one meant going to the teams
screen, founding an organisation, and only then adding a vault to it — which the
NEW VAULT button named after the team, so a team with three of them held three
vaults called the same thing and nothing told them apart. Somebody who wants to
share four servers with two colleagues is not asking to found anything.

So the form asks for a name and nothing else. The team is derived from it, slug
included, and created with this account as its owner; the vault goes inside; and
the members, roles, invitations and key holders that hang off a team are all on
screen the moment it exists. The tab strip's New vault entry lands there with the
new vault selected, which is where the next thing anybody wants to do already is.

That is two calls, and the first can succeed alone. When it does the team is
kept: the id is minted once into pendingVaultTeamId, so pressing CREATE again
resends the identical create — which the server treats as the same team — and
retries the vault, and the message says all of that rather than "creating the
vault failed". Archiving the orphan instead would be a client deleting something
on the user's behalf because a later step failed, which is the kind of tidying
that eventually archives a team somebody has just been added to. A slug taken by
somebody else is retried once with a disambiguated one and never in a loop; a
name with no a-z or 0-9 anywhere in it falls back to the team's own id rather
than to a refusal pointing at a field nobody was shown.

The other half is the caret beside Vaults. Being in four teams means four teams'
machines in front of you all day, and the answer is a switch per vault rather
than four sign-ins. Switching one off takes its hosts, groups, keys and pins off
the screens that list them and does nothing else: it still syncs, its key stays
in the keyring, it stays choosable as somewhere to file a new item, and a shown
host that authenticates with a key filed in it still connects. That last one is
what shaped the design. TryBuildAuthentication resolves a binding out of the
keychain's typed list and a cross-vault binding is legal, so filtering the reload
loops — the obvious implementation — would have turned a preference about reading
into an outage. Only the projections a person reads consult IsVaultShown; every
Reload*Async stays whole, including the dialled-endpoint set that decides which
pins are described as unused, because that is a hint which invites deleting
trust.

Snippets, logs and buckets needed no code and the comment says so out loud: all
three read ActiveVaultId alone, and the personal vault is drawn in the menu
ticked and cannot be switched off — it is the active vault, the group and tag
editors' target, and the save picker's fallback, so hiding it would empty half
the application rather than filter it.

The preference is a column on the cache's vault row, which is what makes it
survive both a relaunch and the /me refresh that runs every minute: Apply does
not touch it, deliberately, because the server has never been told which vaults
this machine is showing. It is in the encrypted cache rather than settings.json
because it is a list of vault ids and that file's own doc comment says what may
go in it. VaultSession cannot see the type at all — ReadableVaults is what the
sync loop walks, and a filter reaching it would be a vault that quietly stopped
syncing, found out weeks later from a host that was never there.

The strip's note refusing a MenuFlyout stands and is unchanged. This flyout
sidesteps the question rather than answering it: the handler selects the Vaults
tab first, which collapses the renderer, so nothing native is under the popup by
the time it opens — the move QuickConnect already makes. A headless test asserts
that ordering, which is as far as headless can go with no native window, and
manual check 1.6 is the other half.

The phone is out of scope on purpose: it has no tab strip and its teams screen's
vault section is read-only. The plumbing is in Client.Shell, so it can adopt this
later; until then nothing there is ever hidden, which is today's behaviour.

1514 tests pass. Fifteen are new in VaultVisibilityTests, and the ones worth
naming are the guards: a hidden vault still syncs, still holds keys that
authenticate hosts on screen, still appears in the save picker, and still counts
towards which pins nothing dials.

Not fixed, and noted here because it is next door: VaultGrantService's team-vault
create refuses a taken vault id rather than returning the existing vault, while
VaultSharing's own remark claims a create whose response was lost is safe to
resend. A lost 200 therefore leaves a vault whose key the client's catch already
zeroed, openable by nobody.

src/DodoSSH.Client.Shell/ViewModels/KnownHostsViewModel.cs

@@ -137,7 +137,23 @@ internal sealed partial class KnownHostsViewModel : ObservableObject
     [ObservableProperty]
     private KnownHostRowViewModel? selected;
 
-    internal bool HasPins => vault.KnownHostPins.Count > 0;
+    /// <summary>
+    /// The pins from vaults this machine is showing, before the filter box narrows them.
+    /// </summary>
+    /// <remarks>
+    /// Every count and every sentence on this screen is taken from here rather than from
+    /// <c>vault.KnownHostPins</c>, so none of them can describe a pin the list is not drawing — a summary
+    /// saying "3 that no host dials" over two rows would send somebody looking for a third.
+    /// <para>
+    /// The vault's own list stays whole and this is a projection of it, which is the rule stated on
+    /// <c>VaultViewModel.IsVaultShown</c>: the trust the SSH handshake consults is read straight out of
+    /// <c>VaultKnownHostStore</c> and has never come through either list.
+    /// </para>
+    /// </remarks>
+    private IEnumerable<KnownHostRowViewModel> Shown =>
+        vault.KnownHostPins.Where(pin => vault.IsVaultShown(pin.VaultId));
+
+    internal bool HasPins => Shown.Any();
 
     internal bool HasVisiblePins => VisiblePins.Count > 0;
 
@@ -153,14 +169,14 @@ internal sealed partial class KnownHostsViewModel : ObservableObject
     {
         get
         {
-            var total = vault.KnownHostPins.Count;
+            var total = Shown.Count();
 
             if (total == 0)
             {
                 return string.Empty;
             }
 
-            var unused = vault.KnownHostPins.Count(pin => !pin.IsDialledByAHost);
+            var unused = Shown.Count(pin => !pin.IsDialledByAHost);
             var pins = total == 1 ? "1 approved host key" : $"{total} approved host keys";
 
             return unused == 0
@@ -169,10 +185,21 @@ internal sealed partial class KnownHostsViewModel : ObservableObject
         }
     }
 
-    internal string EmptyMessage => HasPins
-        ? "No approved host key matches that."
-        : "Nothing approved yet. The first time you connect to a host, its fingerprint is shown for you to "
-            + "check — approving it puts it here.";
+    /// <remarks>
+    /// The hidden-vault case is its own sentence rather than falling into "nothing approved yet", which
+    /// would be a screen telling somebody they have never approved a host key while the keys they approved
+    /// sit in a vault they switched off in a menu.
+    /// </remarks>
+    internal string EmptyMessage => (HasPins, vault.KnownHostPins.Count) switch
+    {
+        (true, _) => "No approved host key matches that.",
+        (false, > 0) =>
+            "Every approved host key here is in a vault you have switched off. Press the ⌄ beside Vaults in "
+            + "the tab strip to switch one back on.",
+        _ =>
+            "Nothing approved yet. The first time you connect to a host, its fingerprint is shown for you "
+            + "to check — approving it puts it here.",
+    };
 
     /// <summary>Withdraws trust in the selected pin.</summary>
     /// <remarks>
@@ -212,7 +239,7 @@ internal sealed partial class KnownHostsViewModel : ObservableObject
 
         VisiblePins.Clear();
 
-        foreach (var pin in vault.KnownHostPins.Where(Matches))
+        foreach (var pin in Shown.Where(Matches))
         {
             VisiblePins.Add(pin);
         }

src/DodoSSH.Client.Shell/ViewModels/MainWindowViewModel.cs

@@ -17,6 +17,36 @@ using DodoSSH.Crypto;
 
 namespace DodoSSH.Client.Shell.ViewModels;
 
+/// <summary>One vault, as a switch in the tab strip's vault menu.</summary>
+/// <remarks>
+/// A record rebuilt per change rather than an observable row, which is the idiom the rest of these lists
+/// use: the menu is short, it is rebuilt whenever anything about the vault list moves, and a row with a
+/// settable property would be a second copy of a fact the cache already holds.
+/// </remarks>
+/// <param name="VaultId">The vault.</param>
+/// <param name="Name">Its display name, which is plaintext as all vault names are.</param>
+/// <param name="IsPersonal">Whether this is the caller's own vault rather than a team's.</param>
+/// <param name="IsShown">Whether its items are currently drawn.</param>
+internal sealed record VaultToggleViewModel(Guid VaultId, string Name, bool IsPersonal, bool IsShown)
+{
+    /// <summary>What the switch says.</summary>
+    /// <remarks>
+    /// A team vault is marked as one, exactly as it is in the "file this into" picker, and for a weaker
+    /// version of the same reason: two vaults may hold a host with the same label, and which vault a switch
+    /// is about is the only thing that tells the two switches apart.
+    /// </remarks>
+    internal string Display => IsPersonal ? Name : $"{Name} · TEAM";
+
+    /// <summary>Whether this vault can be switched off.</summary>
+    /// <remarks>
+    /// The personal vault cannot. It is the active vault — the one snippets, logs and buckets are read from,
+    /// the one the group and tag editors write to, and the fallback the save-target picker lands on — so
+    /// switching it off would empty half the application rather than filter it. It is still drawn, ticked,
+    /// because a vault missing from a list of vaults reads as something having gone wrong.
+    /// </remarks>
+    internal bool CanHide => !IsPersonal;
+}
+
 /// <summary>Which of the shell's mutually exclusive screens is showing.</summary>
 internal enum ShellState
 {
@@ -348,7 +378,10 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
         // session after unlock, and both go away again on lock. Capturing either would give this screen a
         // reference that outlives what it points at — which for a session means holding vault keys past the
         // moment locking is supposed to have zeroed them.
-        teams = new TeamsViewModel(() => connection, () => Vault?.Session);
+        // The third argument is how a vault made over there reaches the lists and the menu over here: both
+        // are built from the session's vault list, and neither would otherwise learn that it had grown until
+        // something else happened to rebuild them.
+        teams = new TeamsViewModel(() => connection, () => Vault?.Session, OnVaultsChangedAsync);
 
         // Subscribed for the life of the process, because the workspace lives that long and so does the tab
         // list. Detached in DisposeAsync, which is the only point either of them ends.
@@ -1026,7 +1059,10 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
     /// </para>
     /// <para>
     /// A host deleted since it was connected to falls through to the address, which is the honest answer:
-    /// the machine is still there and the keychain no longer knows about it.
+    /// the machine is still there and the keychain no longer knows about it. So does a host in a vault the
+    /// user has switched off, and for the same reason rather than by accident: selecting it would point the
+    /// hosts screen at a row that screen is not drawing, and the grid would null the selection straight back
+    /// out — arriving at the hosts screen with nothing selected and no explanation.
     /// </para>
     /// </remarks>
     [RelayCommand]
@@ -1038,7 +1074,8 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
         }
 
         if (row.HostId is { } hostId
-            && vault.Hosts.FirstOrDefault(host => host.EntityId == hostId) is { } known)
+            && vault.Hosts.FirstOrDefault(host => host.EntityId == hostId) is { } known
+            && vault.IsVaultShown(known.VaultId))
         {
             vault.SelectedHost = known;
             ShowScreen(ShellScreen.Hosts);
@@ -1101,6 +1138,148 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
     [RelayCommand]
     private void ShowVaults() => ShowScreen(vaultsScreen);
 
+    // ---- Which vaults this window is showing ----
+
+    /// <summary>
+    /// This machine's preferences about which vaults are drawn, or null while nothing is open.
+    /// </summary>
+    /// <remarks>
+    /// Held here rather than inside <see cref="VaultViewModel"/> because the menu that changes it is in the
+    /// tab strip, which is this view model's, and the screens that read it are that one's. Rebuilt per
+    /// unlock: it is read out of the cache the session opened, so it cannot outlive the session any more
+    /// than the keyring can.
+    /// </remarks>
+    private VaultVisibility? visibility;
+
+    /// <summary>
+    /// One switch per readable vault, for the menu on the Vaults tab.
+    /// </summary>
+    /// <remarks>
+    /// Somebody in four teams does not want four teams' machines in front of them all day. The switches are
+    /// per window and per machine, and what they change is what is drawn — see <see cref="VaultVisibility"/>
+    /// for the things they deliberately do not change.
+    /// </remarks>
+    internal ObservableCollection<VaultToggleViewModel> VaultToggles { get; } = [];
+
+    /// <summary>Whether the menu has anything to offer.</summary>
+    /// <remarks>
+    /// One vault is the ordinary case — somebody who has never joined a team — and a menu holding a single
+    /// switch that cannot be moved is a menu that answers nothing. The New vault entry is still worth
+    /// having, so this hides the list rather than the flyout.
+    /// </remarks>
+    internal bool HasVaultSwitches => VaultToggles.Count > 1;
+
+    /// <summary>Refills the switches from the vaults this session can read.</summary>
+    /// <remarks>
+    /// The readable ones, not every known one: a vault whose grant awaits re-wrap has nothing that would
+    /// decrypt, so a switch for it would do nothing and say so to nobody. Personal first, then by name,
+    /// which is the order every other vault list in the application uses.
+    /// </remarks>
+    private void RebuildVaultToggles()
+    {
+        VaultToggles.Clear();
+
+        if (Vault is { } open && visibility is { } preferences)
+        {
+            foreach (var readable in open.Session.ReadableVaults
+                .OrderByDescending(row => row.IsPersonal)
+                .ThenBy(row => row.Name, StringComparer.CurrentCulture))
+            {
+                VaultToggles.Add(new VaultToggleViewModel(
+                    readable.VaultId,
+                    readable.Name,
+                    readable.IsPersonal,
+                    preferences.IsShown(readable.VaultId)));
+            }
+        }
+
+        OnPropertyChanged(nameof(HasVaultSwitches));
+    }
+
+    /// <summary>Shows or stops showing one vault's items.</summary>
+    /// <remarks>
+    /// <para>
+    /// The personal vault is drawn in the menu, ticked, and cannot be switched off — see
+    /// <see cref="VaultToggleViewModel.CanHide"/>. Leaving it out of the list would read as a bug, and
+    /// letting it be switched off would empty the snippet, log and bucket screens at once, since all three
+    /// are read from the active vault alone.
+    /// </para>
+    /// <para>
+    /// Refuses to switch off the last one that is showing. In practice the rule above already makes that
+    /// unreachable; it is here for the session whose personal grant is unreadable, where the alternative is
+    /// an application that looks broken and gives no clue which menu broke it.
+    /// </para>
+    /// </remarks>
+    [RelayCommand]
+    private async Task ToggleVaultAsync(VaultToggleViewModel? row)
+    {
+        if (row is null || Vault is not { } open || visibility is not { } preferences)
+        {
+            return;
+        }
+
+        if (!row.CanHide)
+        {
+            StatusMessage =
+                "Your personal vault is always shown. Everything filed nowhere else lives in it.";
+            return;
+        }
+
+        var hiding = row.IsShown;
+
+        if (hiding && VaultToggles.Count(toggle => toggle.IsShown) <= 1)
+        {
+            StatusMessage = "At least one vault has to be showing.";
+            return;
+        }
+
+        await preferences.SetHiddenAsync(row.VaultId, hiding, CancellationToken.None)
+            .ConfigureAwait(true);
+
+        // The lists first, then the switches: rebuilding the switches is what redraws the menu, and doing it
+        // second means the menu and the screen behind it never disagree, even for a frame.
+        await open.RefreshVaultsAsync(CancellationToken.None).ConfigureAwait(true);
+
+        RebuildVaultToggles();
+
+        StatusMessage = hiding
+            ? $"'{row.Name}' is no longer shown. It still syncs, and hosts that authenticate with its keys "
+                + "still connect."
+            : $"'{row.Name}' is showing again.";
+    }
+
+    /// <summary>Redraws everything built from the session's vault list.</summary>
+    /// <remarks>
+    /// Handed to the teams screen, which is where a vault gets made. The switches come from that list and
+    /// so does every host, key and pin on the vault screens, so both are a vault out of date the moment one
+    /// is created — and neither is on screen at that point, which is exactly why nothing would have noticed.
+    /// </remarks>
+    private async Task OnVaultsChangedAsync(CancellationToken cancellationToken)
+    {
+        if (Vault is { } open)
+        {
+            await open.RefreshVaultsAsync(cancellationToken).ConfigureAwait(true);
+        }
+
+        RebuildVaultToggles();
+    }
+
+    /// <summary>
+    /// Goes to the teams screen with the new-vault form open.
+    /// </summary>
+    /// <remarks>
+    /// A vault gets a team, so the place to make one is the screen that shows teams — where the people, the
+    /// roles and the key holders already are, which is the next thing anybody making a shared vault wants.
+    /// The form asks for a name and nothing else; see <c>TeamsViewModel.CreateVaultAsync</c> for what is
+    /// made behind it.
+    /// </remarks>
+    [RelayCommand]
+    private void ShowNewVault()
+    {
+        ShowScreen(ShellScreen.Team);
+        teams.NewVaultInItsOwnTeamCommand.Execute(null);
+    }
+
     // ---- The phone's connect menu ----
 
     /// <summary>
@@ -1735,6 +1914,10 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
     {
         await AttachStoresAsync(session, cancellationToken).ConfigureAwait(true);
 
+        // Before the vault view model, because that is what reads it — and read at all rather than defaulted
+        // to "everything shown", because a vault somebody set aside last week should still be set aside.
+        visibility = await VaultVisibility.LoadAsync(session, cancellationToken).ConfigureAwait(true);
+
         Vault = new VaultViewModel(
             session,
             workspace,
@@ -1742,7 +1925,8 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
             () => connection,
             ReconnectAsync,
             copyToClipboard,
-            connectionLog);
+            connectionLog,
+            visibility);
         State = ShellState.Unlocked;
 
         // Offered only where it can actually be honoured: a machine that can keep a key, and a profile that
@@ -1758,6 +1942,11 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
 
         await Vault.LoadAsync(cancellationToken).ConfigureAwait(true);
 
+        // After the load, because the switches are built from the vaults the session admitted and the
+        // keyring is filled during it — before, and a machine with a team vault would come up with one
+        // switch until something else rebuilt them.
+        RebuildVaultToggles();
+
         // After the load, because what the transfers screen takes from the vault is the host list and an
         // empty one would leave its picker blank until the next unlock.
         transfers.Attach(Vault, knownHosts, connectionLog, new S3ObjectStoreFactory());
@@ -2037,6 +2226,11 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
             await open.DisposeAsync().ConfigureAwait(true);
         }
 
+        // With the session, because it was read out of that session's cache. Keeping it would be a set of
+        // switches describing vaults nothing can open, offered on a lock screen.
+        visibility = null;
+        RebuildVaultToggles();
+
         LiveSessionCount = workspace.LiveSessionCount;
 
         // A confirmation armed on the preferences screen must not survive onto the unlock screen, where
@@ -2155,6 +2349,11 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
                     await open.DisposeAsync().ConfigureAwait(true);
                 }
 
+                // With the session, as on lock — and here the cache it came from is about to be deleted
+                // outright, so the switches would be describing vaults this machine no longer has a row for.
+                visibility = null;
+                RebuildVaultToggles();
+
                 connection?.Dispose();
                 connection = null;
                 rememberedToken = null;

src/DodoSSH.Client.Shell/ViewModels/TeamsViewModel.cs

@@ -1,9 +1,11 @@
 using System.Collections.ObjectModel;
 using System.Globalization;
+using System.Text;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 using DodoSSH.Client.Api;
 using DodoSSH.Client.Session;
+using DodoSSH.Client.Storage;
 using DodoSSH.Contracts;
 
 namespace DodoSSH.Client.Shell.ViewModels;
@@ -196,10 +198,30 @@ internal sealed record TeamVaultRowViewModel(Guid VaultId, string Name, bool IsR
 /// would be a second copy of something the server is authoritative for.
 /// </para>
 /// </remarks>
+/// <param name="vaultsChanged">
+/// Told when this screen has created a vault, or null where nobody is listening.
+/// <para>
+/// A delegate rather than an event, and optional, for the reason the two dependencies above are functions:
+/// this screen is built once and outlives every lock, so a subscription would be one more thing to detach
+/// at exactly the right moment. The one listener is the shell, which has a tab-strip menu and a set of host
+/// lists that are both a vault out of date the instant this screen makes one.
+/// </para>
+/// </param>
 internal sealed partial class TeamsViewModel(
     Func<IVaultServer?> connection,
-    Func<VaultSession?> session) : ObservableObject
+    Func<VaultSession?> session,
+    Func<CancellationToken, Task>? vaultsChanged = null) : ObservableObject
 {
+    /// <summary>
+    /// How long a slug may be, mirroring the server's own cap.
+    /// </summary>
+    /// <remarks>
+    /// Mirrored rather than shared because it belongs to <c>TeamService.RequireSlug</c>, which is server
+    /// code this assembly does not reference. Being wrong here costs a refusal the user cannot act on, so
+    /// it is a constant with a comment rather than a number in the middle of a method.
+    /// </remarks>
+    private const int MaximumSlugLength = 128;
+
     /// <summary>Teams this account belongs to.</summary>
     internal ObservableCollection<TeamRowViewModel> Teams { get; } = [];
 
@@ -249,6 +271,36 @@ internal sealed partial class TeamsViewModel(
     [ObservableProperty]
     private string newTeamSlug = string.Empty;
 
+    // ---- Creating a vault ----
+
+    [ObservableProperty]
+    private bool isCreatingVault;
+
+    [ObservableProperty]
+    private string newVaultName = string.Empty;
+
+    /// <summary>
+    /// The team the vault being named will belong to, or null for one made along with it.
+    /// </summary>
+    /// <remarks>
+    /// Captured when the form is armed rather than read from <see cref="SelectedTeam"/> when CREATE is
+    /// pressed, for the reason <see cref="TeamActionRequest"/> carries its own ids: a click in the team
+    /// list between the two would otherwise redirect a vault into a team the user was not looking at when
+    /// they typed its name.
+    /// </remarks>
+    private Guid? newVaultTeamId;
+
+    /// <summary>
+    /// The team a half-finished create already made, held so the retry does not make a second one.
+    /// </summary>
+    /// <remarks>
+    /// Creating a vault of its own is two calls, and the first can succeed while the second fails. The id
+    /// is generated once and kept here, which is the whole of the idempotency story: <c>TeamService</c>
+    /// treats an identical repeat of a create it has already accepted as the same team rather than a new
+    /// one, so pressing CREATE again resends the first call harmlessly and then retries the second.
+    /// </remarks>
+    private Guid? pendingVaultTeamId;
+
     // ---- Renaming a team ----
 
     [ObservableProperty]
@@ -327,6 +379,17 @@ internal sealed partial class TeamsViewModel(
     /// <summary>Whether the selected team has any invitation worth drawing a list for.</summary>
     internal bool HasInvitations => Invitations.Count > 0;
 
+    /// <summary>Where the vault being named will end up, in one line under the box.</summary>
+    /// <remarks>
+    /// Worth a sentence because the form is in the left column and one of the two ways to open it is a
+    /// button in the right pane — so "which team is this going into" is a question the user can reasonably
+    /// have, and the answer was fixed when they pressed the button rather than by whatever is selected now.
+    /// </remarks>
+    internal string NewVaultDestination => newVaultTeamId is { } teamId
+        && Teams.FirstOrDefault(row => row.TeamId == teamId) is { } team
+            ? $"in the team '{team.Name}'"
+            : "in a new team of its own, which you will own. Invite people to it once it is made.";
+
     internal bool AddsAsViewer => NewMemberRole == TeamMemberRole.Viewer;
 
     internal bool AddsAsMember => NewMemberRole == TeamMemberRole.Member;
@@ -357,7 +420,16 @@ internal sealed partial class TeamsViewModel(
     /// called the gated version would find the gate held by itself and skip the reload silently — leaving
     /// a team that was created moments ago missing from the list it was just added to.
     /// </remarks>
-    private async Task ReloadAsync(CancellationToken cancellationToken)
+    /// <param name="select">
+    /// The team to land on, or null to keep the one already selected.
+    /// <para>
+    /// Here rather than assigned after the call, because the assignment fires
+    /// <see cref="OnSelectedTeamChanged"/> and that starts a read nothing can await — so a caller wanting
+    /// the new team's vaults on screen would be racing a fire-and-forget. Passed in, the reselect happens
+    /// under the same guard as every other one and the detail read below is the awaited one.
+    /// </para>
+    /// </param>
+    private async Task ReloadAsync(CancellationToken cancellationToken, Guid? select = null)
     {
         if (connection() is not { } server)
         {
@@ -370,7 +442,7 @@ internal sealed partial class TeamsViewModel(
             return;
         }
 
-        var selectedId = SelectedTeam?.TeamId;
+        var selectedId = select ?? SelectedTeam?.TeamId;
 
         var teams = await server.Teams.ListTeamsAsync(cancellationToken).ConfigureAwait(true);
 
@@ -457,9 +529,9 @@ internal sealed partial class TeamsViewModel(
 
             IsCreatingTeam = false;
 
-            await ReloadAsync(cancellationToken).ConfigureAwait(true);
-
-            SelectedTeam = Teams.FirstOrDefault(row => row.TeamId == created.TeamId) ?? SelectedTeam;
+            // Selected through the reload rather than assigned after it, so the new team's members and
+            // vaults are on screen by the time this returns — see the select parameter.
+            await ReloadAsync(cancellationToken, select: created.TeamId).ConfigureAwait(true);
 
             Status = $"Created '{created.Name}'. Add a vault to it, then share that vault's key with "
                 + "whoever needs it.";
@@ -823,28 +895,224 @@ internal sealed partial class TeamsViewModel(
         }).ConfigureAwait(true);
     }
 
-    /// <summary>Creates a vault owned by the selected team.</summary>
+    /// <summary>Opens the name-a-vault form, aimed at the selected team.</summary>
+    [RelayCommand]
+    private void NewVault() => ArmNewVault(SelectedTeam?.TeamId);
+
+    /// <summary>Opens the name-a-vault form, aimed at a team that does not exist yet.</summary>
+    /// <remarks>
+    /// What the tab strip's vault menu reaches. From there a vault is the thing being made and a team is
+    /// what carries it, which is the way round most people mean it: somebody who wants to share four
+    /// servers with two colleagues is not asking to found an organisation first.
+    /// </remarks>
+    [RelayCommand]
+    private void NewVaultInItsOwnTeam() => ArmNewVault(null);
+
+    /// <summary>Abandons the name-a-vault form.</summary>
+    /// <remarks>
+    /// Clears the half-finished create with it. Cancelling is the one place somebody says they are done
+    /// with this attempt, so a team left behind by a failed second call stops being something the next
+    /// CREATE will add a vault to — it stays in the list, where they can archive it or use it.
+    /// </remarks>
+    [RelayCommand]
+    private void CancelNewVault()
+    {
+        IsCreatingVault = false;
+        pendingVaultTeamId = null;
+        Status = string.Empty;
+    }
+
+    /// <summary>
+    /// Creates a vault, and the team to own it where there is not one already.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// <b>A vault always belongs to a team, and this is what keeps that from being the user's problem.</b>
+    /// Naming a vault is enough: the team is derived from the name, created with this account as its owner,
+    /// and the vault goes into it. What that buys is the rest of this screen — members, roles, invitations
+    /// and key holders all hang off the team, so they are all there the moment the vault is.
+    /// </para>
+    /// <para>
+    /// <b>Two calls, and the first can succeed alone.</b> When it does, the team is kept rather than tidied
+    /// away — see <see cref="pendingVaultTeamId"/> for how the retry avoids a second one. Archiving it here
+    /// would be a client deleting something on the user's behalf because a later step failed, which is the
+    /// kind of cleanup that eventually archives a team somebody has just been added to.
+    /// </para>
+    /// </remarks>
     [RelayCommand]
     private async Task CreateVaultAsync(CancellationToken cancellationToken)
     {
-        if (connection() is not { } server
-            || session() is not { } open
-            || SelectedTeam is not { } team)
+        if (connection() is not { } server)
         {
+            Status = "Offline. Creating a vault needs a connection.";
             return;
         }
 
-        await RunAsync(async () =>
+        if (session() is not { } open)
         {
-            var vault = await open
-                .CreateTeamVaultAsync(server.Teams, team.TeamId, team.Name, cancellationToken)
+            Status = "Unlock your keychain first: a vault's key is generated on this machine.";
+            return;
+        }
+
+        var name = NewVaultName.Trim();
+
+        if (name.Length == 0)
+        {
+            Status = "A vault needs a name.";
+            return;
+        }
+
+        await RunAsync(() => AddVaultAsync(server, open, name, cancellationToken)).ConfigureAwait(true);
+    }
+
+    /// <summary>The two calls behind <see cref="CreateVaultAsync"/>, once its arguments are known good.</summary>
+    private async Task AddVaultAsync(
+        IVaultServer server,
+        VaultSession open,
+        string name,
+        CancellationToken cancellationToken)
+    {
+        var teamId = newVaultTeamId
+            ?? await EnsureTeamForVaultAsync(server, name, cancellationToken).ConfigureAwait(true);
+
+        StoredVault vault;
+
+        try
+        {
+            vault = await open
+                .CreateTeamVaultAsync(server.Teams, teamId, name, cancellationToken)
                 .ConfigureAwait(true);
+        }
+        catch (Exception exception) when (pendingVaultTeamId is not null
+            && exception is not OperationCanceledException)
+        {
+            // The whole state, not "creating the vault failed". The team is real, it is about to appear in
+            // the list on the left, and pressing CREATE again finishes the job rather than making a second
+            // one — none of which the user can work out from the failure alone.
+            await ReloadAsync(cancellationToken, select: pendingVaultTeamId).ConfigureAwait(true);
 
-            await ReloadAsync(cancellationToken).ConfigureAwait(true);
+            Status = $"The team '{name}' was created, but its vault was not: {exception.Message} Press "
+                + "CREATE again to add the vault to it — the team is already in the list on the left.";
+            return;
+        }
 
-            Status = $"Created the vault '{vault.Name}'. It is yours alone until you share its key; new "
-                + "hosts and credentials can be filed into it from the Vault screen.";
-        }).ConfigureAwait(true);
+        IsCreatingVault = false;
+        pendingVaultTeamId = null;
+        NewVaultName = string.Empty;
+
+        await ReloadAsync(cancellationToken, select: teamId).ConfigureAwait(true);
+
+        // After the reload, so this screen is already right when the rest of the shell redraws against the
+        // same session. Nothing here depends on it having happened.
+        if (vaultsChanged is { } notify)
+        {
+            await notify(cancellationToken).ConfigureAwait(true);
+        }
+
+        Status = $"Created the vault '{vault.Name}'. You are the only one who can open it until you share "
+            + "its key — add people below, then press SHARE KEY.";
+    }
+
+    /// <summary>Makes the team a new vault will belong to, or returns the one a retry already made.</summary>
+    /// <remarks>
+    /// The slug is derived rather than asked for. It is a URL-safe handle the server needs and not a thing
+    /// somebody naming a vault has an opinion about, so making them invent one would be a second field for
+    /// a fact the first one already contains.
+    /// </remarks>
+    private async Task<Guid> EnsureTeamForVaultAsync(
+        IVaultServer server,
+        string name,
+        CancellationToken cancellationToken)
+    {
+        var teamId = pendingVaultTeamId ?? Guid.CreateVersion7();
+
+        // Before the call, not after: if this throws, the id has to survive so the retry resends the same
+        // request rather than creating a second team.
+        pendingVaultTeamId = teamId;
+
+        var slug = Slugify(name, teamId);
+
+        try
+        {
+            await server.Teams
+                .CreateTeamAsync(new CreateTeamRequest(teamId, name, slug, null), cancellationToken)
+                .ConfigureAwait(true);
+        }
+        catch (DodoSshApiException exception)
+            when (string.Equals(exception.Code, ProblemCodes.TeamSlugTaken, StringComparison.Ordinal))
+        {
+            // Once, and not in a loop. A second collision on a suffixed slug means something other than
+            // "somebody already has this name", and a client that kept trying would be hammering a server
+            // that is refusing for a reason retrying cannot fix.
+            await server.Teams
+                .CreateTeamAsync(
+                    new CreateTeamRequest(teamId, name, Disambiguate(slug, teamId), null),
+                    cancellationToken)
+                .ConfigureAwait(true);
+        }
+
+        return teamId;
+    }
+
+    /// <summary>
+    /// Turns a vault name into a slug the server will accept.
+    /// </summary>
+    /// <remarks>
+    /// Mirrors <c>TeamService.RequireSlug</c>: lowercase, anything outside a-z0-9 becomes a hyphen, runs of
+    /// hyphens collapse, and the ends are trimmed. A name with nothing sluggable in it — one written
+    /// entirely in a non-Latin script, or in emoji — leaves nothing behind, so it falls back to the team's
+    /// own id rather than to a refusal the user cannot see the cause of in what they typed.
+    /// </remarks>
+    private static string Slugify(string name, Guid teamId)
+    {
+        var slug = new StringBuilder(name.Length);
+
+        foreach (var character in name.ToLowerInvariant())
+        {
+            if (character is >= 'a' and <= 'z' or >= '0' and <= '9')
+            {
+                slug.Append(character);
+            }
+            else if (slug.Length > 0 && slug[^1] != '-')
+            {
+                slug.Append('-');
+            }
+        }
+
+        var trimmed = slug.ToString().Trim('-');
+
+        if (trimmed.Length > MaximumSlugLength)
+        {
+            trimmed = trimmed[..MaximumSlugLength].TrimEnd('-');
+        }
+
+        return trimmed.Length > 0 ? trimmed : Disambiguate("vault", teamId);
+    }
+
+    /// <summary>Adds enough of the team's id to a slug to get past one somebody else has taken.</summary>
+    private static string Disambiguate(string slug, Guid teamId)
+    {
+        var suffix = "-" + teamId.ToString("N", CultureInfo.InvariantCulture)[..8];
+        var room = MaximumSlugLength - suffix.Length;
+
+        return (slug.Length > room ? slug[..room].TrimEnd('-') : slug) + suffix;
+    }
+
+    /// <summary>Opens the name-a-vault form, aimed wherever the caller says.</summary>
+    private void ArmNewVault(Guid? teamId)
+    {
+        // Opening the form is a fresh attempt, so a team left behind by a create that got half way is not
+        // carried into it — the name box has just been emptied, and a retry that reused the team would put
+        // a vault called one thing inside a team called another. Finishing the half-done one is pressing
+        // CREATE again on the form that is still open, which is what its message says.
+        pendingVaultTeamId = null;
+
+        newVaultTeamId = teamId;
+        NewVaultName = string.Empty;
+        IsCreatingVault = true;
+        Status = string.Empty;
+
+        OnPropertyChanged(nameof(NewVaultDestination));
     }
 
     /// <summary>
@@ -1061,6 +1329,10 @@ internal sealed partial class TeamsViewModel(
         OnPropertyChanged(nameof(OwnsSelected));
         OnPropertyChanged(nameof(HasInvitations));
         OnPropertyChanged(nameof(IsOnline));
+
+        // The hint under the name box reads a team out of the list this method is called after refilling,
+        // so it is stale until something says otherwise — and it has no backing field to notify for it.
+        OnPropertyChanged(nameof(NewVaultDestination));
     }
 
     /// <remarks>

src/DodoSSH.Client.Shell/ViewModels/VaultViewModel.cs

@@ -1005,6 +1005,14 @@ internal delegate Task<IVaultServer?> ServerReconnectHandler(CancellationToken c
 /// clipboard rather than one that failed to copy, and the difference is worth saying out loud.
 /// </para>
 /// </param>
+/// <param name="visibility">
+/// Which vaults this machine has been asked to leave off the screens, or null where nothing is hidden.
+/// <para>
+/// Read by <see cref="IsVaultShown"/> and by nothing else in here, which is the whole of how this stays a
+/// display filter — see that method. Null rather than a required argument because "no preference" is the
+/// state every caller that does not care about this is in, including a locked launch and every test.
+/// </para>
+/// </param>
 internal sealed partial class VaultViewModel(
     VaultSession session,
     TerminalWorkspace workspace,
@@ -1012,7 +1020,8 @@ internal sealed partial class VaultViewModel(
     Func<IVaultServer?> connection,
     ServerReconnectHandler? reconnect = null,
     Func<string, Task>? copyToClipboard = null,
-    ConnectionRecorder? connectionLog = null) : ObservableObject, IAsyncDisposable
+    ConnectionRecorder? connectionLog = null,
+    VaultVisibility? visibility = null) : ObservableObject, IAsyncDisposable
 {
     /// <remarks>
     /// A minute. The pull is a delta keyed on a cursor, so an idle pass is one small request and costs the
@@ -1089,6 +1098,45 @@ internal sealed partial class VaultViewModel(
     /// </remarks>
     internal VaultSession Session => session;
 
+    /// <summary>Whether a vault's items are drawn on the screens that list them.</summary>
+    /// <remarks>
+    /// <para>
+    /// <b>The one place the visibility preference is read, and it is read only by the projections a person
+    /// looks at</b> — <see cref="Matches"/>, <see cref="RebuildVaultItems"/>, the group and tag card counts,
+    /// and the pin list. Every <c>Reload*Async</c> above stays complete, and that is not tidiness:
+    /// </para>
+    /// <list type="bullet">
+    /// <item>
+    /// <see cref="Keys"/> and <see cref="Credentials"/> are what <see cref="TryBuildAuthentication"/>
+    /// resolves a host's binding out of, and a host in one vault may legitimately name a key filed in
+    /// another. Filtering the lists rather than the table would make hiding a vault break connections to
+    /// hosts that are still on screen.
+    /// </item>
+    /// <item>
+    /// <see cref="groupsById"/> decides what port a host dials. Hiding a vault must never change that.
+    /// </item>
+    /// <item>
+    /// The dialled-endpoint set in <see cref="ReloadKnownHostsAsync"/> decides which pins are described as
+    /// unused, which is a hint that invites deleting trust.
+    /// </item>
+    /// </list>
+    /// <para>
+    /// Nothing outside those projections asks. Sync walks <c>session.ReadableVaults</c>, the keyring is
+    /// filled from the same list, and the trust the SSH handshake consults is read straight out of
+    /// <c>VaultKnownHostStore</c> — none of which has ever come through this type.
+    /// </para>
+    /// </remarks>
+    internal bool IsVaultShown(Guid vaultId) => visibility?.IsShown(vaultId) ?? true;
+
+    /// <summary>Whether anything at all is being kept off the screens.</summary>
+    /// <remarks>
+    /// What lets an empty grid say why it is empty rather than implying the vault is. Computed from the
+    /// vaults this session can read rather than from the hidden set, because a hidden vault whose grant has
+    /// since been withdrawn is not a reason to tell somebody to go and unhide something.
+    /// </remarks>
+    internal bool HasHiddenVaults =>
+        visibility is not null && session.ReadableVaults.Any(vault => visibility.IsHidden(vault.VaultId));
+
     /// <summary>The hosts to show, unpushed local state included.</summary>
     /// <remarks>
     /// Every host, unfiltered. This is what the connect path resolves bindings against and what the pinned
@@ -1117,21 +1165,31 @@ internal sealed partial class VaultViewModel(
     /// What the hosts grid says when it has nothing in it.
     /// </summary>
     /// <remarks>
-    /// Three answers rather than one, because "there are no hosts", "this group is empty" and "nothing
-    /// matches what you typed" are three different situations and only the first is an invitation to add
-    /// something. Telling somebody with thirty machines to add their first one is answering a question they
-    /// did not ask.
+    /// Four answers rather than one, because "there are no hosts", "you have set a vault aside", "this group
+    /// is empty" and "nothing matches what you typed" are four different situations and only the first is an
+    /// invitation to add something. Telling somebody with thirty machines to add their first one is
+    /// answering a question they did not ask.
+    /// <para>
+    /// The hidden-vault answer comes before the group and the search box, because it is the one an empty
+    /// grid cannot otherwise explain: a filter the user typed is still in front of them, and an open group
+    /// is still lit on a card, but a vault switched off in a menu two screens ago leaves nothing on screen
+    /// to read.
+    /// </para>
     /// </remarks>
-    internal string NoVisibleHostsMessage => (Hosts.Count, GroupFilter, HostFilter.Trim().Length) switch
-    {
-        (0, _, _) =>
-            "No hosts yet. Press + NEW HOST to add one, or import the machines already in this computer's "
-            + "~/.ssh/config from Preferences.",
-        (_, not null, 0) =>
-            "Nothing is filed under this group yet. Press ALL HOSTS above, then drag a host card onto this "
-            + "group's card — or choose the group in a host's own editor.",
-        _ => "No host matches that. The name, the address and the notes are all searched.",
-    };
+    internal string NoVisibleHostsMessage =>
+        (Hosts.Count, HasHiddenVaults, GroupFilter, HostFilter.Trim().Length) switch
+        {
+            (0, _, _, _) =>
+                "No hosts yet. Press + NEW HOST to add one, or import the machines already in this "
+                + "computer's ~/.ssh/config from Preferences.",
+            (_, true, null, 0) =>
+                "Every host here is in a vault you have switched off. Press the ⌄ beside Vaults in the tab "
+                + "strip to switch one back on.",
+            (_, _, not null, 0) =>
+                "Nothing is filed under this group yet. Press ALL HOSTS above, then drag a host card onto "
+                + "this group's card — or choose the group in a host's own editor.",
+            _ => "No host matches that. The name, the address and the notes are all searched.",
+        };
 
     /// <summary>
     /// What the sidebar's list actually holds: the visible hosts, with group headings between them.
@@ -2630,11 +2688,36 @@ internal sealed partial class VaultViewModel(
         await LoadConflictsAsync(cancellationToken).ConfigureAwait(true);
     }
 
+    /// <summary>Redraws every list from the vault, without saying anything about it.</summary>
+    /// <remarks>
+    /// For the two things that change which vaults exist or which are drawn without going through this type
+    /// at all: a vault created on the Teams screen, and a switch in the tab strip's vault menu. Both leave
+    /// the lists on screen describing the world as it was a moment ago, and neither has a sentence worth
+    /// printing — which is exactly what the quiet reload is for. Also refreshes the empty-state sentence,
+    /// which is computed and has no change notification of its own.
+    /// </remarks>
+    internal async Task RefreshVaultsAsync(CancellationToken cancellationToken)
+    {
+        await ReloadAsync(cancellationToken).ConfigureAwait(true);
+
+        OnPropertyChanged(nameof(HasHiddenVaults));
+        OnPropertyChanged(nameof(NoVisibleHostsMessage));
+    }
+
     /// <summary>Refills the "file this into" picker from the vaults this session can read and write.</summary>
     /// <remarks>
+    /// <para>
     /// The selection is restored by id rather than kept, because the option objects are rebuilt. Where the
     /// previously selected vault has gone — a grant withdrawn, a team left — it falls back to the active
     /// vault rather than to nothing, so the next Save still has somewhere to go.
+    /// </para>
+    /// <para>
+    /// <b>Deliberately not filtered by <see cref="IsVaultShown"/>.</b> Hiding is a preference about reading,
+    /// and a destination you cannot choose is a vault you cannot put anything in — so switching a team's
+    /// vault off to get its forty hosts out of the way would quietly stop you filing anything into it, which
+    /// nobody asked for. The same goes for the transfers screen's host picker, which reads
+    /// <see cref="Hosts"/> for the same reason.
+    /// </para>
     /// </remarks>
     private void RebuildTargetVaults()
     {
@@ -2968,8 +3051,11 @@ internal sealed partial class VaultViewModel(
 
         foreach (var tag in tagItems)
         {
+            // Over the shown vaults, for the reason the group counts are — see RebuildGroups.
             Tags.Add(new TagRowViewModel(
-                tag, Hosts.Count(row => row.Host.TagIds.Contains(tag.EntityId))));
+                tag,
+                Hosts.Count(row =>
+                    row.Host.TagIds.Contains(tag.EntityId) && IsVaultShown(row.VaultId))));
         }
 
         SelectedTag = Tags.FirstOrDefault(row => row.EntityId == selectedId);
@@ -3031,7 +3117,10 @@ internal sealed partial class VaultViewModel(
 
         foreach (var group in groupItems)
         {
-            var count = Hosts.Count(row => row.Host.GroupId == group.EntityId);
+            // Counted over the shown vaults rather than over every host, so a card cannot claim members the
+            // grid beside it is not drawing. Not counted over VisibleHosts, which would be both too early —
+            // that list is rebuilt after this — and wrong: a card must not lose members to the search box.
+            var count = Hosts.Count(row => row.Host.GroupId == group.EntityId && IsVaultShown(row.VaultId));
 
             Groups.Add(new HostGroupRowViewModel(group, count));
         }
@@ -3414,6 +3503,13 @@ internal sealed partial class VaultViewModel(
     /// </remarks>
     private bool Matches(HostRowViewModel row)
     {
+        // First, and ahead of both the cards and the box, because it is not a search: a hidden vault's host
+        // is out however the grid is narrowed, and a count taken after this reflects what is on screen.
+        if (!IsVaultShown(row.VaultId))
+        {
+            return false;
+        }
+
         // The group cards, and they narrow before the box does — a host outside the chosen group is out
         // whatever was typed. The two are deliberately not one control: the box is what you type when you
         // know the name, and the cards are what you press when you do not.
@@ -7139,6 +7235,12 @@ internal sealed partial class VaultViewModel(
     /// Ordered by name inside each kind, and by kind in the merged view — keys, then passwords, then pins.
     /// Not one flat alphabetical run: the three behave completely differently, and a list that interleaved
     /// them would put a pin nobody created between two things somebody did.
+    /// <para>
+    /// This is where a hidden vault's keys and passwords come off the keychain — the table rather than
+    /// <see cref="Keys"/> and <see cref="Credentials"/> themselves, which stay whole for the reason
+    /// <see cref="IsVaultShown"/> gives. Tags and buckets are read from the active vault alone, which
+    /// cannot be hidden, so neither needs a test of its own.
+    /// </para>
     /// </remarks>
     private void RebuildVaultItems()
     {
@@ -7148,7 +7250,7 @@ internal sealed partial class VaultViewModel(
 
         if (Section is VaultSection.All or VaultSection.Keys)
         {
-            foreach (var key in Keys)
+            foreach (var key in Keys.Where(row => IsVaultShown(row.VaultId)))
             {
                 VaultItems.Add(new VaultItemRowViewModel(
                     VaultItemKind.Key,
@@ -7163,7 +7265,7 @@ internal sealed partial class VaultViewModel(
 
         if (Section is VaultSection.All or VaultSection.Credentials)
         {
-            foreach (var credential in Credentials)
+            foreach (var credential in Credentials.Where(row => IsVaultShown(row.VaultId)))
             {
                 VaultItems.Add(new VaultItemRowViewModel(
                     VaultItemKind.Credential,