Pane Split Policy

The reusable app shell can create split panes, but the decision to clone a session is application-owned. That matters for SSH providers, MFA prompts, credential scopes, and any transport that cannot be duplicated without host logic.

RoyalApps.RoyalTerminal.Avalonia.App exposes ITerminalPaneSplitPolicy so hosts can allow PTY splits, deny SSH splits, or provide a custom cloned launch profile.

Public API

Type	Purpose
ITerminalPaneSplitPolicy	Evaluates every split request before the shell creates the new pane.
TerminalPaneSplitContext	Immutable context describing the source pane and default cloned launch profile.
TerminalPaneSplitDecision	Allows or denies the split and can provide a replacement launch profile.
AllowAllTerminalPaneSplitPolicy	Built-in policy that allows every transport.
DelegateTerminalPaneSplitPolicy	Built-in adapter for host callback logic.
TransportAllowListTerminalPaneSplitPolicy	Built-in policy that allows only selected transport ids.
TerminalPaneSplitPolicies	Factory and shared instances for common policies.

The split direction enum used by the policy is TerminalPaneSplitRequest from RoyalTerminal.Avalonia.Controls.

Built-In Policies

Allow everything:

MainWindow window = new()
{
    PaneSplitPolicy = TerminalPaneSplitPolicies.AllowAll,
};

Allow only PTY splits:

MainWindow window = new()
{
    PaneSplitPolicy = TerminalPaneSplitPolicies.PtyOnly,
};

Allow selected transport ids:

MainWindow window = new()
{
    PaneSplitPolicy = TerminalPaneSplitPolicies.AllowTransports(
        TerminalTransportIds.Pty,
        TerminalTransportIds.Pipe),
};

Custom Clone Strategy

Use DelegateTerminalPaneSplitPolicy when the host must inspect or replace the launch profile.

MainWindow window = new()
{
    PaneSplitPolicy = new DelegateTerminalPaneSplitPolicy(context =>
    {
        if (context.SourceTransportId == TerminalTransportIds.Ssh)
        {
            return TerminalPaneSplitDecision.Deny(
                "Split panes are disabled for SSH sessions in this application.");
        }

        return TerminalPaneSplitDecision.Allow();
    }),
};

For a custom SSH provider such as Rebex, the callback can build a replacement TerminalSessionProfile that scopes credential prompts, MFA state, or provider objects to the new pane.

PaneSplitPolicy = new DelegateTerminalPaneSplitPolicy(context =>
{
    if (context.SourceTransportId != TerminalTransportIds.Ssh)
    {
        return TerminalPaneSplitDecision.Allow();
    }

    TerminalSessionProfile clone = context.DefaultLaunchProfile with
    {
        DisplayName = $"{context.TabTitle} SSH pane",
    };

    return TerminalPaneSplitDecision.Allow(
        clone,
        "Created a new SSH pane with app-owned authentication policy.");
});

Context Fields

TerminalPaneSplitContext includes:

• requested split direction;
• tab title;
• source pane id and optional title;
• source profile id;
• source transport id and transport profile id;
• source working directory;
• whether the source pane currently has an active session;
• the source launch profile captured from the pane;
• the default launch profile the shell would use.

The shell creates a new independent TerminalControl session when the decision is allowed. It does not share a PTY, SSH channel, or transport instance between panes.

Relationship To Pane Layout

ITerminalPaneSplitPolicy lives in the app-shell package because it depends on session profiles and product workflow decisions. The lower-level pane layout helpers live in RoyalApps.RoyalTerminal.Avalonia and can be used without this policy layer.

See Terminal Pane Layout API for the control-level pane tree and split grid helpers.