Decide what Lock does to a running shell, and say it

Pressing Lock nulled and disposed the vault view model and touched nothing else.
TerminalWorkspace is injected from App.axaml.cs and outlives every lock, so the SSH
connection, the pty and the pump all kept running while the window said "Unlock your
vault" — and since 0500e43 collapsed the WebView while locked, that live session was
invisible as well as unstopped. CloseSessionAsync was reachable in production only from
DisposeAsync, i.e. shutdown. None of this was written down anywhere, so it was neither a
policy nor a bug, which is the actual problem.

Shells now deliberately outlive the lock, and every layer says so.

The reason to prefer this over making Lock a disconnect: locking is what a person does
when they walk away from the machine, which is exactly when a long upgrade, build or
transfer is most likely to be in flight. Ending every shell would make Lock a button that
destroys work, and the predictable response is to stop pressing it and leave the vault
open instead. The idle auto-lock this will grow decides it outright — an unattended
timeout that killed a running job would be worse than the exposure it removes. Closing
the channel also buys less than it looks: the session was authorised at connect time by a
credential the remote verified itself, and no vault key participates in keeping it alive,
so locking cannot retroactively un-authorise it any more than removing a member can.

Stated honestly rather than implied, because the lock screen is what hides it:

- The unlock screen shows how many shells are still connected, and that locking closes
  the vault and not the connections — so a machine still holding authenticated SSH
  channels does not present itself as merely "locked". Shown only when there is something
  to disclose. Quitting is what ends them, and the text admits that.
- The Lock button carries the same thing in a tooltip, since its name implies the
  opposite of what it does to a shell.
- README lists it as a third architecture consequence beside non-retroactive revocation,
  which is the same shape of honest limit; docs/crypto.md §10 records it as a threat-model
  boundary; TerminalWorkspace and LockAsync carry the argument next to the code.

LiveSessionCount deliberately does not count dictionary entries. Nothing removes a
session when the remote closes the channel by itself — RunSessionAsync only drops the
renderer registration — so sessions.Count would report a shell that exited half an hour
ago as still running, on the one screen where a user is deciding whether it is safe to
walk away. A completed Run task is what "the shell is gone" actually looks like. While
locked the number can only fall, since opening a session needs the vault, so a stale
value over-reports rather than under-reports.

Both new tests fail when the policy is reverted: the count test times out against
sessions.Count, and the shell test reports "workspace.LiveSessionCount should be 1 but was
0" when Lock closes sessions. ShellFlowTests also stops building its workspace with a real
SshNetConnectionFactory that nothing ever called, which had made the suite's independence
from the network a coincidence rather than a property.

Verified by hand with a live shell, which nothing had done: a harness mirroring
MainWindow.axaml's 340,* grid with a real NativeWebView, the shipped WebAssets, a real
sshd in a container, and an ISshShellSession decorator recording every window-change the
remote is actually told about. Across lock and unlock, no window-change reached the remote
at all, stty size answered 50 118 before and after, the renderer's own buffer came back
byte for byte with the wrapped line intact, and the session stayed live throughout. A
control run that never hides the WebView behaves identically, so nothing above is startup
or idle behaviour. Keystrokes injected while locked reach nothing: twelve of twelve
SendInput events accepted with the harness confirmed as the foreground window, no probe
character in the remote's output, and a following Ctrl-U answered BEL, so nothing was
queued in the line editor either. A hidden WS_CHILD window is not eligible for keyboard
focus, which is what makes surviving the lock defensible rather than merely convenient.

Correction to a claim made in f80b3d4: terminal.js's guard comment listed "a host that
hides the WebView while the vault is locked" among the paths that reach a degenerate fit.
It does not. Collapsing the control hides a native child window without resizing it, so
the page still reports paneWidth 840 and paneHeight 760 with unchanged cols and rows, no
ResizeObserver callback fires and the fit never runs. Establishing that rather than
assuming it: the same cycle with MINIMUM_FITTABLE_PIXELS patched to 0 — the guard fully
disabled — is equally clean. The guard is still right for minimising and for a splitter
dragged to the edge; it is simply not what makes locking safe, and must not be cited as
though it were.

Recorded, not fixed:

- Nothing closes one terminal from the interface, so a user reading "1 shell is still
  connected" can only act on it by quitting. CloseSessionAsync is tested and correct;
  VaultViewModel discards the session id it would need.
- A session whose remote exits keeps its ISshConnection, and the thread ShellStream parks,
  until the process ends.
- Suspected and seen once: before the harness waited for the window's scale to settle, a
  DPI settle pushed a 2202x1328 pane for a window 1180 logical units wide and a later
  re-push reflowed the wrapped line. Three later runs at RenderScaling 1.00 never showed
  it, so it is filed as a lead, not a finding.
- WebView2 fails to initialise with CO_E_SERVER_EXEC_FAILURE when the host executable
  sits under a very long path. Cost an hour on the harness; relevant to packaging.

README.md

@@ -25,13 +25,21 @@ zero-knowledge.
 | Vault | End-to-end encrypted; X25519 + Ed25519 + XChaCha20-Poly1305, Argon2id unlock |
 | Connections | Client-direct SSH by default, with an optional raw-TCP server relay |
 
-Two consequences worth knowing before you read further:
+Three consequences worth knowing before you read further:
 
 - **Revocation is not retroactive.** A removed member keeps what they already downloaded. The
   real remediation is rotating the SSH credential, so offboarding is built around a rotation
   checklist rather than a button that implies more than it delivers.
 - **No session recording in relay mode.** The relay forwards SSH ciphertext, so it cannot see
   commands. That is the cost of the relay not being able to read your traffic.
+- **Locking the vault does not close your shells.** Lock closes the vault and zeroes every key it
+  held; a session that authenticated before it keeps running, because the remote host never
+  consulted the vault and the credential was already spent. That is deliberate — you lock when you
+  walk away from the machine, which is exactly when a long upgrade or transfer is most likely to be
+  in flight, and an idle auto-lock that killed it would be worse than the exposure it removed. The
+  honest reading is that *locked* describes the vault and not this machine's access to your hosts.
+  The unlock screen therefore shows how many shells are still connected, and quitting DodoSSH is
+  what ends them.
 
 The reasoning behind each major decision is recorded in [`docs/adr/`](docs/adr/), starting with
 [the E2EE trust model](docs/adr/0001-e2ee-trust-model.md).

docs/crypto.md

@@ -499,5 +499,13 @@ server, its operators, its backups and the network. It does **not** address:
 - metadata — item counts, sizes, timestamps, access patterns and the sharing graph are
   visible, as are host addresses for relay-enabled hosts;
 - a weak passphrase — §2 parameters and passphrase entropy are the whole defence;
+- **a locked vault on a machine with open sessions** — locking zeroes the identity keys, the vault
+  keys and the cache key, so nothing on disk can be read again without the passphrase. It does not
+  touch an SSH channel that is already open: that channel was authorised at connect time by a
+  credential the remote host verified itself, and no vault key participates in keeping it alive.
+  Sessions therefore survive lock **by design** (the client says so on its unlock screen, and the
+  README explains why), which means a locked client can still hold authenticated access to remote
+  hosts. Ending that is quitting the client, or rotating the credential — the same non-retroactive
+  limit as revocation, one layer down;
 - supply chain — a server can serve a backdoored client. Sign releases with a key the server
   does not hold. In a self-hosted E2EE product this is the largest practical hole.

docs/platform-flags.md

@@ -108,6 +108,50 @@ Related and not yet addressed: the conflict log above the terminal is an `ItemsC
 `ScrollViewer` and no `MaxHeight` on an `Auto` row, so enough conflicts squeeze the terminal row toward
 nothing.
 
+**The lock/unlock cycle does not resize the pane at all, and the 40 px guard is not what makes it safe.**
+Measured on Windows with a live shell, against a real `sshd` in a container, in a harness mirroring
+`MainWindow.axaml`'s `340,*` grid: with the `NativeWebView` collapsed by `IsVisible=false`, the page still
+reports `paneWidth: 840, paneHeight: 760`, unchanged `cols`/`rows`, and `visibilityState: "visible"`.
+Hiding is `SetWindowPos(holder, …, SWP_HIDEWINDOW)`, which does not resize the holder, so no
+`ResizeObserver` callback fires, no fit runs, and **no `window-change` reaches the remote** — before,
+during or after the cycle. `stty size` on the remote answered `50 118` both before locking and after
+unlocking, and the renderer's own buffer came back byte for byte, wrapped lines included.
+
+The guard's irrelevance here was established rather than assumed: the same run with
+`MINIMUM_FITTABLE_PIXELS` patched to `0` — the guard fully disabled — produced an identical clean result.
+So the guard is still worth keeping for the paths it was written for, minimising and a splitter dragged to
+the edge, but it is **not** on the lock path and must not be cited as the reason locking is safe. It was
+described that way when it landed.
+
+Two further results from the same harness, both about the deliberate decision that shells outlive a lock
+(README, `MainWindowViewModel.LockAsync`):
+
+- **A collapsed WebView cannot be typed into.** With the harness confirmed as the foreground window and
+  all twelve injected `SendInput` events accepted, not one character of the probe reached the remote pty,
+  and a `Ctrl-U` afterwards answered `BEL` — nothing was sitting in the remote's line editor either. A
+  hidden `WS_CHILD` window is not eligible for keyboard focus, so the lock screen is a real input barrier
+  even though the session behind it is live. That is what makes surviving the lock defensible rather than
+  merely convenient.
+- **The session survives the cycle in the real control, not only in tests.** `LiveSessionCount` was 1
+  before, during and after, and the shell accepted a command again immediately on unlock.
+
+*Suspected, seen once, not reproduced:* on the first run — before the harness learned to wait for the
+window's scale to settle — the window opened at 2558x1367 px and the page reported a 2202x1328 pane
+(312x88 characters) for a window 1180 logical units wide, which looks like physical pixels arriving where
+CSS pixels were expected. A later re-push to 1177x672 then reflowed the wrapped line and split it in two.
+Both events straddled a DPI settle rather than the lock, and three later runs at `RenderScaling 1.00`
+never showed it. If a user reports mangled scrollback after moving the window between displays of
+different scale, start here.
+
+**WebView2 will not initialise when the host executable sits under a very long path.**
+`CreateCoreWebView2Environment` fails with `COMException 0x80080005 CO_E_SERVER_EXEC_FAILURE` ("Server
+execution failed") and the terminal never appears. Hit while building the harness above: the same binary
+that failed from a ~230-character directory ran first time from `%TEMP%\h`. The exact threshold was not
+established and the mechanism is unconfirmed — the user data folder is created beside the executable by
+default and the browser process is launched with paths derived from it, so `MAX_PATH` is the obvious
+suspect. Relevant to packaging: an installer that lands under a deep per-user path would break the
+terminal with an error that names nothing.
+
 **Nothing hands the terminal keyboard focus after connecting.** The page calls `term.focus()`, which focuses
 the textarea inside the document, but Avalonia's focus is still on the Connect button — so the first
 keystrokes after a successful connect go to the shell's UI, not to the remote shell. Click inside the

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

@@ -139,6 +139,22 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
     [ObservableProperty]
     private VaultViewModel? vault;
 
+    /// <summary>
+    /// Shells that were left running when the vault was locked.
+    /// </summary>
+    /// <remarks>
+    /// Refreshed by <see cref="LockAsync"/>, which is where the policy this reports is explained.
+    /// </remarks>
+    [ObservableProperty]
+    private int liveSessionCount;
+
+    internal bool HasLiveSessions => LiveSessionCount > 0;
+
+    /// <summary>The count as a sentence, because a bare number on a lock screen explains nothing.</summary>
+    internal string LiveSessionSummary => LiveSessionCount == 1
+        ? "1 shell is still connected and still running."
+        : $"{LiveSessionCount} shells are still connected and still running.";
+
     /// <summary>Where the embedded browser should navigate.</summary>
     internal Uri TerminalPageUrl => workspace.PageUrl;
 
@@ -335,7 +351,34 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
             }).ConfigureAwait(true);
     }
 
-    /// <summary>Closes the vault and forgets every key it held.</summary>
+    /// <summary>
+    /// Closes the vault and forgets every key it held. Open shells keep running.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// <b>Lock is a vault operation, and deliberately not a disconnect.</b> The reason a person locks is
+    /// that they are walking away from the machine, which is exactly the moment a long upgrade, build or
+    /// transfer is most likely to be in flight — so killing every shell would make Lock a button that
+    /// destroys work, and the predictable response is to stop using it and leave the vault open instead.
+    /// The same argument decides it for the idle auto-lock this will grow: an unattended timeout that
+    /// terminated a running job would be worse than the exposure it removes.
+    /// </para>
+    /// <para>
+    /// <b>What "locked" therefore describes.</b> Disposing the vault zeroes the identity keys, the vault
+    /// keys and the cache key, so nothing on disk can be read without the passphrase again. It says
+    /// nothing about this machine's access to remote hosts: an SSH channel authenticated at connect time
+    /// needs no vault key to keep running, and the credential it used was already spent. Locking cannot
+    /// retroactively un-authorise a session any more than revocation can — the same honest limit the
+    /// README records for a removed team member. So a locked DodoSSH still holds open, authenticated
+    /// channels, and <see cref="LiveSessionCount"/> is shown on the unlock screen rather than left to be
+    /// inferred from a terminal that the lock screen hides.
+    /// </para>
+    /// <para>
+    /// The count is a snapshot taken here. While locked it can only fall — opening a session needs the
+    /// vault — so a stale value over-reports and never under-reports, which is the safe direction for a
+    /// warning of this kind.
+    /// </para>
+    /// </remarks>
     [RelayCommand]
     private async Task LockAsync()
     {
@@ -345,6 +388,8 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
             await open.DisposeAsync().ConfigureAwait(true);
         }
 
+        LiveSessionCount = workspace.LiveSessionCount;
+
         State = ShellState.Locked;
         StatusMessage = "Locked.";
     }
@@ -464,6 +509,12 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
         return exception.Message;
     }
 
+    partial void OnLiveSessionCountChanged(int value)
+    {
+        OnPropertyChanged(nameof(HasLiveSessions));
+        OnPropertyChanged(nameof(LiveSessionSummary));
+    }
+
     partial void OnStateChanged(ShellState value)
     {
         OnPropertyChanged(nameof(IsStarting));

src/DodoSSH.Client.App/Views/MainWindow.axaml

@@ -68,7 +68,12 @@
             <Button Content="Sign in" Command="{Binding SignInCommand}"
                     IsVisible="{Binding !IsOnline}" />
             <Button Content="Sync" Command="{Binding Vault.SyncCommand}" />
-            <Button Content="Lock" Command="{Binding LockCommand}" />
+            <!--
+              The tooltip carries the policy to the point of action, because the button's name implies
+              the opposite of what it does to a running shell.
+            -->
+            <Button Content="Lock" Command="{Binding LockCommand}"
+                    ToolTip.Tip="Closes the vault and forgets its keys. Open shells keep running and reappear when you unlock." />
           </StackPanel>
         </Grid>
       </Border>
@@ -312,6 +317,23 @@
             <TextBlock Classes="hint" Text="{Binding StatusMessage}" />
             <TextBlock Classes="hint" FontSize="11"
                        Text="This works with no network: the salt and the wrapped key are already on this machine." />
+
+            <!--
+              Stated here because the lock screen is what hides it. The terminal's WebView is collapsed
+              while locked, so a shell left running is invisible as well as unstopped — and a screen
+              saying "Unlock your vault" over a machine that still holds authenticated SSH channels is
+              exactly the kind of half-truth this project writes down instead of implying. Visible only
+              when there is something to disclose, so an ordinary launch stays quiet.
+            -->
+            <Border Background="#1b2432" CornerRadius="4" Padding="10,8"
+                    IsVisible="{Binding HasLiveSessions, FallbackValue=False}">
+              <StackPanel Spacing="4">
+                <TextBlock Text="{Binding LiveSessionSummary}" Foreground="#bcd2ea"
+                           FontWeight="SemiBold" TextWrapping="Wrap" />
+                <TextBlock Classes="hint" FontSize="11"
+                           Text="Locking closes the vault, not your terminals: a job you started keeps running, and its output is waiting behind this screen. It also means this machine still holds an open, authenticated channel to those hosts — locked describes the vault, not the connections. Quit DodoSSH to end them." />
+              </StackPanel>
+            </Border>
           </StackPanel>
         </Border>
 

src/DodoSSH.Client.App/WebAssets/terminal.js

@@ -135,12 +135,17 @@ function activate(sessionId) {
   }
 }
 
-// Below this, a pane is not being looked at — it is minimised, dragged to nothing, or the host has
-// hidden its window. Fitting anyway would be actively harmful rather than merely useless: the fit addon
-// floors its proposal at 2 columns by 1 row, so a degenerate viewport reflows the *remote* pty to 2x1
-// through window-change, and the wrapped scrollback that produces cannot be recovered when the pane comes
-// back. A guard rather than a fix for one caller, because several paths reach here — a minimised window, a
-// splitter dragged to the edge, and a host that hides the WebView while the vault is locked.
+// Below this, a pane is not being looked at — it is minimised or dragged to nothing. Fitting anyway would
+// be actively harmful rather than merely useless: the fit addon floors its proposal at 2 columns by 1 row,
+// so a degenerate viewport reflows the *remote* pty to 2x1 through window-change, and the wrapped
+// scrollback that produces cannot be recovered when the pane comes back. A guard rather than a fix for one
+// caller, because more than one path reaches here: a minimised window, and a splitter dragged to the edge
+// once splits land.
+//
+// It is *not* what protects the vault's lock screen, which an earlier version of this comment claimed.
+// Collapsing the host's WebView hides a native child window without resizing it, so this page's viewport
+// does not change, no observer fires and this function is never called — measured with a live shell, and
+// confirmed by removing the guard and finding the lock cycle equally clean. See docs/platform-flags.md.
 const MINIMUM_FITTABLE_PIXELS = 40;
 
 function resize(session, sessionId) {

src/DodoSSH.Client.Terminal/TerminalWorkspace.cs

@@ -6,10 +6,19 @@ namespace DodoSSH.Client.Terminal;
 /// Owns the loopback data plane and every live terminal session.
 /// </summary>
 /// <remarks>
+/// <para>
 /// One data plane and one renderer page for the whole application, with a session id per terminal.
 /// Not one WebView per tab: each WebView2 is a separate browser process, so twenty tabs would mean
 /// twenty renderer processes and several hundred megabytes for a working set a user would call
 /// ordinary. Splits and tabs are layout inside the single page.
+/// </para>
+/// <para>
+/// <b>A session's lifetime is the application's, not the vault's.</b> This object is composed once at
+/// startup and outlives every lock, deliberately: locking the vault zeroes keys, and a shell needs no
+/// vault key to keep running, so a job started before the lock keeps running through it. That is a
+/// policy rather than an oversight — <c>MainWindowViewModel.LockAsync</c> says why, and the shell shows
+/// <see cref="LiveSessionCount"/> on the unlock screen so it is not a hidden state.
+/// </para>
 /// </remarks>
 public sealed class TerminalWorkspace : IAsyncDisposable
 {
@@ -37,6 +46,25 @@ public sealed class TerminalWorkspace : IAsyncDisposable
     /// <summary>Where the WebView should navigate.</summary>
     public Uri PageUrl => dataPlane.PageUrl;
 
+    /// <summary>
+    /// How many terminals still have a live shell behind them.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// Not <c>sessions.Count</c>, which over-reports. Nothing removes an entry when the remote closes
+    /// the channel on its own — <see cref="RunSessionAsync"/> only drops the renderer registration — so
+    /// a session whose shell exited half an hour ago is still in the dictionary. A completed
+    /// <c>Run</c> task is what "the shell is gone" actually looks like: the pump's loops have finished
+    /// and it has already sent <c>SessionClosed</c> to the renderer.
+    /// </para>
+    /// <para>
+    /// This exists because the shell shows the number on the unlock screen, and a lock screen that
+    /// claims a shell is still running when it is not would be the same class of dishonesty the number
+    /// is there to prevent.
+    /// </para>
+    /// </remarks>
+    public int LiveSessionCount => sessions.Values.Count(session => !session.Run.IsCompleted);
+
     /// <summary>Starts the loopback listener.</summary>
     public void Start() => server = dataPlane.RunAsync(lifetime.Token);
 
@@ -84,7 +112,15 @@ public sealed class TerminalWorkspace : IAsyncDisposable
         return sessionId;
     }
 
-    /// <summary>Closes one terminal.</summary>
+    /// <summary>
+    /// Closes one terminal.
+    /// </summary>
+    /// <remarks>
+    /// Reached only from <see cref="DisposeAsync"/> today, which is a consequence of the lifetime policy
+    /// above rather than an accident: nothing else in the application ends a session, because locking
+    /// deliberately does not and there is no per-tab close in the interface yet. It is here, and tested,
+    /// because closing one terminal without taking the process down is what a tab close needs.
+    /// </remarks>
     public async Task CloseSessionAsync(uint sessionId)
     {
         if (!sessions.Remove(sessionId, out var session))

tests/DodoSSH.Client.App.Tests/FakeSshConnections.cs

@@ -0,0 +1,86 @@
+using DodoSSH.Client.Ssh;
+
+namespace DodoSSH.Client.App.Tests;
+
+/// <summary>
+/// An SSH layer that connects to nothing and hands out shells that simply stay open.
+/// </summary>
+/// <remarks>
+/// This suite has no network and no <c>sshd</c>; what it needs from a session is only that one can exist
+/// and outlive a lock. The real factory was here before and was never called by anything, which made the
+/// suite's independence from the network a coincidence rather than a property.
+/// </remarks>
+internal sealed class IdleSshConnectionFactory : ISshConnectionFactory
+{
+    /// <inheritdoc />
+    public Task<ISshConnection> ConnectAsync(
+        SshConnectionRequest request,
+        CancellationToken cancellationToken) =>
+        Task.FromResult<ISshConnection>(new IdleConnection(request));
+}
+
+/// <summary>A connection whose shells never end by themselves.</summary>
+internal sealed class IdleConnection(SshConnectionRequest request) : ISshConnection
+{
+    /// <inheritdoc />
+    public bool IsConnected { get; private set; } = true;
+
+    /// <inheritdoc />
+    public HostKeyPresentation HostKey { get; } =
+        new(request.Host, request.Port, "ssh-ed25519", "SHA256:idle");
+
+    /// <inheritdoc />
+    public Task<ISshShellSession> OpenShellAsync(
+        TerminalSize size,
+        CancellationToken cancellationToken) =>
+        Task.FromResult<ISshShellSession>(new IdleShell());
+
+    /// <inheritdoc />
+    public ValueTask DisposeAsync()
+    {
+        IsConnected = false;
+
+        return ValueTask.CompletedTask;
+    }
+}
+
+/// <summary>
+/// A shell that is connected, silent, and ends only when something ends it.
+/// </summary>
+/// <remarks>
+/// Which is what the interesting case looks like from the host's side: a remote sitting in the middle of
+/// a long job produces nothing for minutes and must not be mistaken for one that has exited.
+/// </remarks>
+internal sealed class IdleShell : ISshShellSession
+{
+    /// <inheritdoc />
+    public bool IsOpen { get; private set; } = true;
+
+    /// <inheritdoc />
+    public async ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken)
+    {
+        // Never returns 0 of its own accord: 0 would tell the pump the remote closed the channel, which
+        // is the opposite of what this stands in for.
+        await Task.Delay(System.Threading.Timeout.InfiniteTimeSpan, cancellationToken)
+            .ConfigureAwait(false);
+
+        return 0;
+    }
+
+    /// <inheritdoc />
+    public ValueTask WriteAsync(ReadOnlyMemory<byte> data, CancellationToken cancellationToken) =>
+        ValueTask.CompletedTask;
+
+    /// <inheritdoc />
+    public void Resize(TerminalSize size)
+    {
+    }
+
+    /// <inheritdoc />
+    public ValueTask DisposeAsync()
+    {
+        IsOpen = false;
+
+        return ValueTask.CompletedTask;
+    }
+}

tests/DodoSSH.Client.App.Tests/ShellFlowTests.cs

@@ -57,7 +57,10 @@ public sealed class ShellFlowTests : IAsyncLifetime
                 {
                     ["/terminal"] = new("text/html; charset=utf-8", "<!doctype html>"u8.ToArray()),
                 }),
-            new SshNetConnectionFactory(knownHosts),
+
+            // Idle rather than real: a session in this suite has to be able to exist and to outlive a
+            // lock, and none of it should be able to reach a network.
+            new IdleSshConnectionFactory(),
             TimeProvider.System);
 
         shell = new MainWindowViewModel(
@@ -415,6 +418,68 @@ public sealed class ShellFlowTests : IAsyncLifetime
         shell.State.ShouldBe(ShellState.Unlocked);
     }
 
+    /// <summary>
+    /// The deliberate half of what Lock does: the vault closes, the shells do not.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// A policy rather than an implementation detail, which is why it is asserted here. Locking is what a
+    /// person does when they walk away from the machine, and that is exactly when a long job is most
+    /// likely to be running — so ending every shell would make Lock destroy work, and an idle auto-lock
+    /// would do it unattended. <c>MainWindowViewModel.LockAsync</c> carries the full argument.
+    /// </para>
+    /// <para>
+    /// The disclosure is asserted along with the behaviour, because the two are the same decision. A
+    /// lock screen that hides the terminal — which it does, the WebView is collapsed while locked — while
+    /// authenticated SSH channels stay open is only defensible if it says so.
+    /// </para>
+    /// </remarks>
+    [Fact]
+    public async Task LockingKeepsOpenShellsRunning_AndSaysSoOnTheUnlockScreen()
+    {
+        await UnlockedAsync();
+
+        // Opened on the workspace rather than through Connect, because Connect waits for a renderer to
+        // attach and there is no WebView in this suite. What is under test is what Lock does to a session
+        // that exists, not how it came to exist.
+        await workspace.OpenSessionAsync(
+            new SshConnectionRequest("host.invalid", 22, "dodo", new SshPasswordCredential("irrelevant")),
+            TerminalSize.Default,
+            Token);
+
+        workspace.LiveSessionCount.ShouldBe(1);
+
+        await shell.LockCommand.ExecuteAsync(null);
+
+        shell.State.ShouldBe(ShellState.Locked);
+        shell.Vault.ShouldBeNull("the vault's keys are gone");
+
+        workspace.LiveSessionCount.ShouldBe(1, "the shell was still running, so it kept running");
+
+        shell.HasLiveSessions.ShouldBeTrue();
+        shell.LiveSessionCount.ShouldBe(1);
+        shell.LiveSessionSummary.ShouldBe("1 shell is still connected and still running.");
+
+        // And it survives the unlock too, so the session outlives the whole cycle rather than merely
+        // outliving the disposal.
+        shell.Passphrase = Passphrase;
+        await shell.UnlockCommand.ExecuteAsync(null);
+
+        shell.State.ShouldBe(ShellState.Unlocked);
+        workspace.LiveSessionCount.ShouldBe(1);
+    }
+
+    [Fact]
+    public async Task LockingWithNoOpenShells_DisclosesNothing()
+    {
+        await UnlockedAsync();
+
+        await shell.LockCommand.ExecuteAsync(null);
+
+        shell.LiveSessionCount.ShouldBe(0);
+        shell.HasLiveSessions.ShouldBeFalse("an ordinary lock must not warn about nothing");
+    }
+
     // ---- Helpers ----
 
     private static CancellationToken Token => TestContext.Current.CancellationToken;

tests/DodoSSH.Client.Terminal.Tests/FakeShellSession.cs

@@ -101,6 +101,65 @@ internal sealed class FakeShellSession : ISshShellSession
     }
 }
 
+/// <summary>
+/// Hands out <see cref="FakeShellSession"/>s, so a workspace can be driven with no network.
+/// </summary>
+/// <remarks>
+/// Exists for the session-lifetime tests. Everything else in this suite works on a pump directly; the
+/// workspace is the layer that decides when a session is over, and that decision is what needs a
+/// connection whose shell can be made to end on cue.
+/// </remarks>
+internal sealed class FakeConnectionFactory(long bytesPerShell = long.MaxValue) : ISshConnectionFactory
+{
+    /// <summary>Connections handed out, in order.</summary>
+    internal List<FakeConnection> Connections { get; } = [];
+
+    /// <inheritdoc />
+    public Task<ISshConnection> ConnectAsync(
+        SshConnectionRequest request,
+        CancellationToken cancellationToken)
+    {
+        var connection = new FakeConnection(request, bytesPerShell);
+        Connections.Add(connection);
+
+        return Task.FromResult<ISshConnection>(connection);
+    }
+}
+
+/// <summary>A connection that opens fake shells and records its own disposal.</summary>
+internal sealed class FakeConnection(SshConnectionRequest request, long bytesPerShell) : ISshConnection
+{
+    /// <inheritdoc />
+    public bool IsConnected { get; private set; } = true;
+
+    /// <inheritdoc />
+    public HostKeyPresentation HostKey { get; } =
+        new(request.Host, request.Port, "ssh-ed25519", "SHA256:fake");
+
+    /// <summary>The shell this connection opened, if it opened one.</summary>
+    internal FakeShellSession? Shell { get; private set; }
+
+    /// <summary>Whether the connection was disposed, which is what closing a session must do.</summary>
+    internal bool IsDisposed { get; private set; }
+
+    /// <inheritdoc />
+    public Task<ISshShellSession> OpenShellAsync(TerminalSize size, CancellationToken cancellationToken)
+    {
+        Shell = new FakeShellSession(bytesPerShell);
+
+        return Task.FromResult<ISshShellSession>(Shell);
+    }
+
+    /// <inheritdoc />
+    public ValueTask DisposeAsync()
+    {
+        IsDisposed = true;
+        IsConnected = false;
+
+        return ValueTask.CompletedTask;
+    }
+}
+
 /// <summary>Records frames, and can acknowledge them to keep credit flowing.</summary>
 internal sealed class RecordingTransport : ITerminalTransport
 {

tests/DodoSSH.Client.Terminal.Tests/TerminalWorkspaceTests.cs

@@ -0,0 +1,130 @@
+using DodoSSH.Client.Ssh;
+
+namespace DodoSSH.Client.Terminal.Tests;
+
+/// <summary>
+/// How long a terminal session lives, and what the workspace says about it.
+/// </summary>
+/// <remarks>
+/// The count these tests are about is shown to a user on the unlock screen, as the disclosure that
+/// locking the vault leaves shells running. A wrong number there is not a cosmetic bug: it either hides
+/// a live connection or invents one.
+/// </remarks>
+public sealed class TerminalWorkspaceTests
+{
+    private static readonly TimeSpan Timeout = TimeSpan.FromSeconds(10);
+
+    private static InMemoryTerminalAssetProvider StubAssets() =>
+        new(new Dictionary<string, TerminalAsset>(StringComparer.Ordinal)
+        {
+            [TerminalDataPlane.PagePath] = new("text/html; charset=utf-8", "<!doctype html>"u8.ToArray()),
+        });
+
+    private static SshConnectionRequest Request() =>
+        new("host.invalid", 22, "dodo", new SshPasswordCredential("irrelevant"));
+
+    [Fact]
+    public async Task AnOpenSessionIsReportedAsLive()
+    {
+        var connections = new FakeConnectionFactory();
+
+        await using var workspace = new TerminalWorkspace(
+            StubAssets(), connections, TimeProvider.System);
+
+        workspace.LiveSessionCount.ShouldBe(0);
+
+        await workspace.OpenSessionAsync(
+            Request(), TerminalSize.Default, TestContext.Current.CancellationToken);
+
+        workspace.LiveSessionCount.ShouldBe(1);
+
+        await workspace.OpenSessionAsync(
+            Request(), TerminalSize.Default, TestContext.Current.CancellationToken);
+
+        workspace.LiveSessionCount.ShouldBe(2);
+    }
+
+    /// <remarks>
+    /// The case a naive <c>sessions.Count</c> gets wrong. Nothing removes the entry when the remote
+    /// closes the channel by itself — the session is still in the dictionary, holding a connection that
+    /// is finished — so counting entries would report a shell that exited as still running. A user
+    /// deciding whether it is safe to walk away is the person that lie is told to.
+    /// </remarks>
+    [Fact]
+    public async Task ASessionWhoseRemoteHasExitedIsNotReportedAsLive()
+    {
+        // A shell with no output to give: its first read returns 0, which is a remote closing the
+        // channel, so the pump finishes on its own with nobody asking it to.
+        var connections = new FakeConnectionFactory(bytesPerShell: 0);
+
+        await using var workspace = new TerminalWorkspace(
+            StubAssets(), connections, TimeProvider.System);
+
+        await workspace.OpenSessionAsync(
+            Request(), TerminalSize.Default, TestContext.Current.CancellationToken);
+
+        await WaitUntilAsync(() => workspace.LiveSessionCount == 0);
+    }
+
+    [Fact]
+    public async Task ClosingASessionEndsItAndDisposesItsConnection()
+    {
+        var connections = new FakeConnectionFactory();
+
+        await using var workspace = new TerminalWorkspace(
+            StubAssets(), connections, TimeProvider.System);
+
+        var sessionId = await workspace.OpenSessionAsync(
+            Request(), TerminalSize.Default, TestContext.Current.CancellationToken);
+
+        await workspace.CloseSessionAsync(sessionId);
+
+        workspace.LiveSessionCount.ShouldBe(0);
+        connections.Connections.ShouldHaveSingleItem().IsDisposed.ShouldBeTrue();
+    }
+
+    /// <remarks>
+    /// Disposal is the one path that does close sessions, because it is process shutdown. Asserted so
+    /// that the SSH connections are known to be released rather than assumed to be.
+    /// </remarks>
+    [Fact]
+    public async Task DisposingTheWorkspaceClosesEverySession()
+    {
+        var connections = new FakeConnectionFactory();
+
+        var workspace = new TerminalWorkspace(StubAssets(), connections, TimeProvider.System);
+
+        await workspace.OpenSessionAsync(
+            Request(), TerminalSize.Default, TestContext.Current.CancellationToken);
+        await workspace.OpenSessionAsync(
+            Request(), TerminalSize.Default, TestContext.Current.CancellationToken);
+
+        await workspace.DisposeAsync();
+
+        workspace.LiveSessionCount.ShouldBe(0);
+        connections.Connections.Count.ShouldBe(2);
+        connections.Connections.ShouldAllBe(connection => connection.IsDisposed);
+    }
+
+    /// <remarks>
+    /// Polled rather than awaited on a task, because the point is what an observer of the property
+    /// sees: the pump ends on a thread of its own, and the count has to catch up without anyone
+    /// telling it to.
+    /// </remarks>
+    private static async Task WaitUntilAsync(Func<bool> condition)
+    {
+        var deadline = TimeProvider.System.GetUtcNow() + Timeout;
+
+        while (TimeProvider.System.GetUtcNow() < deadline)
+        {
+            if (condition())
+            {
+                return;
+            }
+
+            await Task.Delay(20, TestContext.Current.CancellationToken);
+        }
+
+        throw new TimeoutException($"The condition was still false after {Timeout}.");
+    }
+}