Let a closed terminal take its own status line with it

The strip along the bottom is one line for the whole window, and connecting
writes to it, so "Connected to prod-db." outlived the tab it was about: close
prod-db, look at the terminal beside it, and the bar was still reporting on a
session that is no longer there.

A connection's own lines are now owned by the attempt that wrote them, and
closing a tab clears the line only when that is what the bar is holding.
Ownership rather than a blanket clear on close, because the alternative loses
the sentences this bar exists for — a failed save or a refused sync is what the
design deleted the bar's other four fields to make room for, and closing a
terminal is no answer to one.

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

@@ -25,6 +25,14 @@
     channel this application has for saying that a save failed, that a sync was refused, that a merge picked
     a winner. The design is a mock-up of a working afternoon and has nowhere for a sentence like that to go;
     dropping the bar would have meant dropping the sentence, or repeating it on six screens.
+
+    ── One line, several terminals ────────────────────────────────────────────────────────────────────────
+    One bar for a window that now holds any number of tabs, and connecting writes to it — so "Connected to
+    prod-db." outlived the tab it was about, and closing prod-db left that sentence sitting under whichever
+    terminal the user looked at next. A connection's own lines are now owned by the attempt that wrote them
+    and are cleared when its tab is closed; everything else the vault says stays, because closing a terminal
+    is not an answer to a failed save. See VaultViewModel.ForgetConnectionStatus and
+    MainWindowViewModel.CloseTabAsync.
   -->
 
   <Border Height="24" Background="{StaticResource Chrome}"

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

@@ -1924,9 +1924,18 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
     /// Closes one terminal, ending its shell.
     /// </summary>
     /// <remarks>
+    /// <para>
     /// This is the one thing in the application that deliberately ends a session, which is why it is a tab's
     /// close button and not a menu item: closing the window somebody's job is running in should take exactly
     /// as much intent as it looks like it does. Locking does not do this, and neither does anything else.
+    /// </para>
+    /// <para>
+    /// <b>It takes the status line with it, when that line is this tab's.</b> The strip along the bottom is
+    /// one line for the whole window — see <c>StatusBar.axaml</c> — and connecting writes to it, so closing
+    /// prod-db used to leave "Connected to prod-db." reporting on a session that is gone, over whichever
+    /// terminal the user looked at next. Only the sentence this attempt wrote goes; anything the vault has
+    /// said since stays, because a failed save is not something closing a terminal answers.
+    /// </para>
     /// </remarks>
     [RelayCommand]
     private async Task CloseTabAsync(TerminalTabViewModel tab)
@@ -1960,6 +1969,9 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
 
         RaiseTabState();
 
+        // Only this tab's own sentence, and only if that is what the bar currently holds — see the remark.
+        Vault?.ForgetConnectionStatus(tab.AttemptId);
+
         // Explicitly, and not left to the selection having moved. Closing a tab that was not the selected one
         // changes nothing about the selection, so OnSelectedTabChanged does not run — and the host whose
         // terminal just went would keep a lit dot until something else happened to move the selection.
@@ -3400,7 +3412,7 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
     /// </remarks>
     private void OnVaultConnectionStarting(object? sender, ConnectionAttemptEventArgs e)
     {
-        var tab = new TerminalTabViewModel(e.Label, e.Address);
+        var tab = new TerminalTabViewModel(e.Label, e.Address) { AttemptId = e.AttemptId };
         attempts[e.AttemptId] = tab;
 
         AdoptTab(tab);
@@ -3429,6 +3441,7 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
             // dropping it would leave a shell running with nothing in the window naming it.
             var adopted = new TerminalTabViewModel(e.SessionId, e.Label, e.Address)
             {
+                AttemptId = e.AttemptId,
                 StartedAt = clock.GetUtcNow(),
                 Cipher = NullIfEmpty(e.Cipher),
                 HostKeyAlgorithm = NullIfEmpty(e.HostKeyAlgorithm),

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

@@ -84,6 +84,18 @@ internal sealed partial class TerminalTabViewModel : ObservableObject
     /// </remarks>
     internal uint SessionId { get; private set; }
 
+    /// <summary>
+    /// The connection attempt this tab was opened for, or <see cref="Guid.Empty"/> for a tab nothing dialled.
+    /// </summary>
+    /// <remarks>
+    /// Carried only so that closing this tab can take the vault's status line with it when the line is about
+    /// this connection — see <c>VaultViewModel.ForgetConnectionStatus</c>. It is the attempt id and not the
+    /// session id because the message can be written before a session exists ("Connecting to prod-db…") and
+    /// after one has stopped existing, and because the two failure sentences a tab can end on never have a
+    /// session id at all.
+    /// </remarks>
+    internal Guid AttemptId { get; init; }
+
     internal string Label { get; }
 
     /// <summary>The account and endpoint, for the pane header and the status bar.</summary>

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

@@ -2130,6 +2130,60 @@ internal sealed partial class VaultViewModel(
     [ObservableProperty]
     private string status = string.Empty;
 
+    /// <summary>
+    /// The connection <see cref="Status"/> is currently about, or <see cref="Guid.Empty"/> when it is about
+    /// something else — a save, a sync, a refusal that has nothing to do with a terminal.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// The status line is one line for the whole window, and most of what goes through it is about the vault,
+    /// which is one thing however many terminals are open. A connection is not: "Connected to prod-db." is
+    /// about one tab, and it used to outlive that tab — close prod-db, look at the terminal beside it, and the
+    /// strip along the bottom was still reporting on a session that is no longer there.
+    /// </para>
+    /// <para>
+    /// Ownership rather than a blanket clear on every close, because the alternative loses the sentences this
+    /// bar exists for: a failed save or a refused sync is what the design deleted the bar's other four fields
+    /// to make room for, and closing a terminal is no reason to take one away.
+    /// </para>
+    /// <para>
+    /// Reset by <see cref="OnStatusChanged"/> on every write, so the only messages that carry an owner are the
+    /// ones <see cref="SayAbout"/> writes. Anything assigning <see cref="Status"/> in the ordinary way says,
+    /// by doing so, that its message belongs to no tab.
+    /// </para>
+    /// </remarks>
+    private Guid statusAttemptId;
+
+    partial void OnStatusChanged(string value) => statusAttemptId = Guid.Empty;
+
+    /// <summary>Writes a status line that belongs to one connection attempt.</summary>
+    /// <remarks>
+    /// After the assignment, not before: <see cref="OnStatusChanged"/> clears the owner on every write, which
+    /// is what makes "belongs to nobody" the default rather than something each of the other status writes
+    /// would have to remember to say.
+    /// </remarks>
+    private void SayAbout(ConnectionAttemptEventArgs attempt, string message)
+    {
+        Status = message;
+        statusAttemptId = attempt.AttemptId;
+    }
+
+    /// <summary>
+    /// Clears the status line if what it is saying is about this connection, and leaves it alone otherwise.
+    /// </summary>
+    /// <remarks>
+    /// Called by the shell when a tab is closed — see <c>MainWindowViewModel.CloseTabAsync</c>. Cleared to
+    /// empty rather than replaced with "Closed prod-db.": the tab going is the report, it is the report the
+    /// user just made happen, and a bar that answers every close with a sentence is a bar people stop reading.
+    /// </remarks>
+    internal void ForgetConnectionStatus(Guid attemptId)
+    {
+        if (attemptId != Guid.Empty && statusAttemptId == attemptId)
+        {
+            Status = string.Empty;
+        }
+    }
+
     [ObservableProperty]
     private int pendingChanges;
 
@@ -10767,7 +10821,7 @@ internal sealed partial class VaultViewModel(
             Dialled(target, authentication));
 
         ConnectionStarting?.Invoke(this, attempt);
-        Status = $"Connecting to {target.Label}…";
+        SayAbout(attempt, $"Connecting to {target.Label}…");
 
         await OpenSessionAsync(attempt, target, authentication, cancellationToken).ConfigureAwait(true);
     }
@@ -11042,7 +11096,9 @@ internal sealed partial class VaultViewModel(
     /// </remarks>
     private void Abandon(ConnectionAttemptEventArgs attempt, string reason)
     {
-        Status = reason;
+        // Owned by the attempt, unlike Answer's own line below: this is the case where the tab stays, carrying
+        // the same reason, so closing that tab is exactly the moment the line stops being about anything.
+        SayAbout(attempt, reason);
 
         ConnectionFailed?.Invoke(
             this,
@@ -11097,7 +11153,7 @@ internal sealed partial class VaultViewModel(
         // only record that machine was reached at all.
         connectionLog?.Identify(sessionId, target.Label, target.HostId);
 
-        Status = $"Connected to {target.Label}.";
+        SayAbout(attempt, $"Connected to {target.Label}.");
 
         // The session the workspace just opened is the only place the negotiated cipher and host-key
         // algorithm live — an SshConnectionRequest asks for neither and gets no say in either — so they are
@@ -11128,7 +11184,8 @@ internal sealed partial class VaultViewModel(
         // screen it is typed on says so.
         if (target.Row is { } row)
         {
-            await RememberTypedPasswordAsync(row, authentication, cancellationToken).ConfigureAwait(true);
+            await RememberTypedPasswordAsync(attempt, row, authentication, cancellationToken)
+                .ConfigureAwait(true);
         }
     }
 
@@ -11160,6 +11217,7 @@ internal sealed partial class VaultViewModel(
     /// </para>
     /// </remarks>
     private async Task RememberTypedPasswordAsync(
+        ConnectionAttemptEventArgs attempt,
         HostRowViewModel row,
         HostAuthentication authentication,
         CancellationToken cancellationToken)
@@ -11175,8 +11233,10 @@ internal sealed partial class VaultViewModel(
 
         if (row.IsReadOnly)
         {
-            Status = $"Connected to {row.Label}. Its password was not saved: this host was written by a "
-                + "newer version of DodoSSH, and binding a credential would re-encode it.";
+            SayAbout(
+                attempt,
+                $"Connected to {row.Label}. Its password was not saved: this host was written by a newer "
+                + "version of DodoSSH, and binding a credential would re-encode it.");
             return;
         }
 
@@ -11200,7 +11260,9 @@ internal sealed partial class VaultViewModel(
         }
         catch (Exception exception)
         {
-            Status = $"Connected to {row.Label}, but its password could not be saved: {exception.Message}";
+            SayAbout(
+                attempt,
+                $"Connected to {row.Label}, but its password could not be saved: {exception.Message}");
             return;
         }
 
@@ -11211,8 +11273,10 @@ internal sealed partial class VaultViewModel(
 
         await ReloadAsync(cancellationToken).ConfigureAwait(true);
 
-        Status = $"Connected to {row.Label}. Its password is saved in your keychain as '{row.Label}', so it "
-            + "will not be asked for again.";
+        SayAbout(
+            attempt,
+            $"Connected to {row.Label}. Its password is saved in your keychain as '{row.Label}', so it will "
+            + "not be asked for again.");
 
         await AutoSyncAsync(cancellationToken).ConfigureAwait(true);
     }

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

@@ -1254,6 +1254,68 @@ public sealed class ShellFlowTests : IAsyncLifetime
         shell.IsTerminalShowing.ShouldBeTrue();
     }
 
+    /// <remarks>
+    /// The status line is one line for the whole window, so a sentence about a session that has been closed is
+    /// a sentence the user reads over some other terminal.
+    /// </remarks>
+    [Fact]
+    public async Task ClosingATab_TakesItsOwnStatusLineWithIt()
+    {
+        var vault = await ReadyToConnectAsync();
+
+        await using var renderer = await FakeRenderer.AttachAsync(workspace, Token);
+
+        await vault.ConnectCommand.ExecuteAsync(null);
+        vault.Status.ShouldContain("Connected", Case.Insensitive);
+
+        await shell.CloseTabCommand.ExecuteAsync(shell.Tabs[0]);
+
+        vault.Status.ShouldBeEmpty();
+    }
+
+    /// <remarks>
+    /// The other half, and the reason closing does not simply blank the bar: everything this application has
+    /// to say about a save, a sync or a refusal goes through the same line — see <c>StatusBar.axaml</c> — and
+    /// closing a terminal answers none of it.
+    /// </remarks>
+    [Fact]
+    public async Task ClosingATab_LeavesAStatusLineThatIsAboutSomethingElse()
+    {
+        var vault = await ReadyToConnectAsync();
+
+        await using var renderer = await FakeRenderer.AttachAsync(workspace, Token);
+
+        await vault.ConnectCommand.ExecuteAsync(null);
+        vault.Status = "The keychain could not be saved.";
+
+        await shell.CloseTabCommand.ExecuteAsync(shell.Tabs[0]);
+
+        vault.Status.ShouldBe("The keychain could not be saved.");
+    }
+
+    /// <remarks>
+    /// Two sessions to the same host, which is the case a label could not tell apart: the line belongs to the
+    /// attempt that wrote it, so closing the other one leaves it alone.
+    /// </remarks>
+    [Fact]
+    public async Task ClosingATab_LeavesTheLineAnotherTabWrote()
+    {
+        var vault = await ReadyToConnectAsync();
+
+        await using var renderer = await FakeRenderer.AttachAsync(workspace, Token);
+
+        await vault.ConnectCommand.ExecuteAsync(null);
+        var first = shell.Tabs[0];
+
+        // The second connection's own line is what the bar holds now.
+        await vault.ConnectCommand.ExecuteAsync(null);
+        var reported = vault.Status;
+
+        await shell.CloseTabCommand.ExecuteAsync(first);
+
+        vault.Status.ShouldBe(reported);
+    }
+
     // ---- Connecting, while it is still happening ----
     //
     // A handshake is a network round trip and no longer holds the vault while it runs, so there is a stretch