live-log-streaming

name	live-log-streaming
description	Stream selected-resource logs into a WPF view without restarting on every poll
domain	logging
confidence	medium
source	earned

Context

Use this when a monitoring UI needs a live log panel tied to a selected resource and the resource list is refreshed periodically in the background.

Patterns

• Keep the active stream keyed by resource name or id, not by view refresh cycle.
• Stop the previous stream before starting a new selection.
• Use cancellation tokens to shut down log readers cleanly.
• Ignore stale log events once the selection has moved.
• Marshal UI updates through the dispatcher, with a null-safe fallback for tests.
• Reuse a shared MainViewModel log buffer for tray windows when the main view already owns the stream.
• Expose an empty-state message and HasLogLines flag so a mini console can render safe fallback UI without extra service calls.

Examples

_activeLogStreamResourceName = resource.Name;
_ = _liveLogsService.StartStreamingAsync(resource.Name);

private void OnLiveLogLineReceived(object? sender, LogLineReceivedEventArgs args)
{
    if (!string.Equals(args.ResourceName, _activeLogStreamResourceName, StringComparison.OrdinalIgnoreCase))
        return;

    AddLogLine(args.LogLine);
}

Anti-Patterns

• Restarting the log stream every time polling updates the resource list.
• Using Application.Current.Dispatcher without a fallback in test contexts.
• Letting stale log events append after the user has changed selection.

Mini Console Reuse

• When a tray-only console is added, bind it to the existing MainViewModel instead of creating a second streaming service.
• Keep the window owned by App.xaml.cs so tray menu actions can open, hide, and dispose it consistently.
• Let the console close by hiding it; keep the shared log buffer alive so reopening is instant.