Introduce HostLaunchPlan and refine launch flow

Add HostLaunchPlan/HostLaunchPlanBuilder to encapsulate host path, package root, working dir, forwarded args and env; add unit tests for builder. Refactor LauncherFlowCoordinator to use HostLaunchPlan when starting hosts, improve IPC handling and startup logic (shorter soft/hard timeouts, more frequent reconnects and shell status polling, activation recovery via existing host). Move argument formatting and environment setup into the plan, include package/working/args metadata in start attempts. Update Commands to prefer ProcessPath for launcher base directory. App and Program: start single-instance activation listener earlier and harden ActivateMainWindow to handle shell initialization state and return richer activation status codes. SingleInstanceService: signal listener readiness (ManualResetEventSlim) and wait briefly when starting, and dispose it. Various logging and minor error handling improvements.

LanMountainDesktop.Tests/HostLaunchPlanBuilderTests.cs

@@ -0,0 +1,100 @@
+using LanMountainDesktop.Launcher;
+using LanMountainDesktop.Launcher.Services;
+using LanMountainDesktop.Shared.Contracts.Launcher;
+using Xunit;
+
+namespace LanMountainDesktop.Tests;
+
+public sealed class HostLaunchPlanBuilderTests : IDisposable
+{
+    private readonly string _testRoot;
+
+    public HostLaunchPlanBuilderTests()
+    {
+        _testRoot = Path.Combine(
+            Path.GetTempPath(),
+            "LanMountainDesktop.HostLaunchPlanTests",
+            Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(_testRoot);
+    }
+
+    [Fact]
+    public void Build_UsesPackageRootAsWorkingDirectory_ForPublishedDeployment()
+    {
+        var packageRoot = Path.Combine(_testRoot, "package-root");
+        var deployment = CreateDeployment(packageRoot, "app-0.8.5.7");
+        var resultPath = Path.Combine(_testRoot, "launcher-result.json");
+        var context = CommandContext.FromArgs(
+        [
+            "launch",
+            "--app-root", packageRoot,
+            "--result", resultPath,
+            "--launch-source", "postinstall",
+            "--custom-host-arg", "custom-value"
+        ]);
+        var locator = new DeploymentLocator(packageRoot);
+        var resolution = locator.ResolveHostExecutable(context);
+
+        var plan = HostLaunchPlanBuilder.Build(context, locator, resolution);
+
+        Assert.Equal(Path.GetFullPath(packageRoot), plan.PackageRoot);
+        Assert.Equal(Path.GetFullPath(packageRoot), plan.WorkingDirectory);
+        Assert.Equal(Path.Combine(deployment, GetExecutableName()), plan.HostPath);
+        Assert.Contains("--launch-source", plan.Arguments);
+        Assert.Contains("postinstall", plan.Arguments);
+        Assert.Contains("--custom-host-arg", plan.Arguments);
+        Assert.Contains("custom-value", plan.Arguments);
+        Assert.DoesNotContain("--app-root", plan.Arguments);
+        Assert.DoesNotContain(packageRoot, plan.Arguments);
+        Assert.DoesNotContain("--result", plan.Arguments);
+        Assert.DoesNotContain(resultPath, plan.Arguments);
+        Assert.Contains($"--{LauncherIpcConstants.PackageRootEnvVar}={Path.GetFullPath(packageRoot)}", plan.Arguments);
+    }
+
+    [Fact]
+    public void Build_KeepsPathsWithSpacesAsSingleArgumentListTokens()
+    {
+        var packageRoot = Path.Combine(_testRoot, "package root with spaces");
+        CreateDeployment(packageRoot, "app-0.8.5.7");
+        var context = CommandContext.FromArgs(["launch", "--app-root", packageRoot]);
+        var locator = new DeploymentLocator(packageRoot);
+        var resolution = locator.ResolveHostExecutable(context);
+
+        var plan = HostLaunchPlanBuilder.Build(context, locator, resolution);
+
+        var packageRootArgument = $"--{LauncherIpcConstants.PackageRootEnvVar}={Path.GetFullPath(packageRoot)}";
+        Assert.Contains(packageRootArgument, plan.Arguments);
+        Assert.Equal(Path.GetFullPath(packageRoot), plan.EnvironmentVariables[LauncherIpcConstants.PackageRootEnvVar]);
+        Assert.DoesNotContain(plan.Arguments, argument => argument.StartsWith("\"", StringComparison.Ordinal));
+        Assert.Equal(Path.GetFullPath(packageRoot), plan.WorkingDirectory);
+    }
+
+    private static string CreateDeployment(string packageRoot, string deploymentName)
+    {
+        var deployment = Path.Combine(packageRoot, deploymentName);
+        Directory.CreateDirectory(deployment);
+        File.WriteAllText(Path.Combine(deployment, GetExecutableName()), string.Empty);
+        File.WriteAllText(Path.Combine(deployment, ".current"), string.Empty);
+        File.WriteAllText(
+            Path.Combine(deployment, "version.json"),
+            """
+            {"Version":"0.8.5.7","Codename":"Administrate"}
+            """);
+        return deployment;
+    }
+
+    private static string GetExecutableName()
+    {
+        return OperatingSystem.IsWindows()
+            ? "LanMountainDesktop.exe"
+            : "LanMountainDesktop";
+    }
+
+    public void Dispose()
+    {
+        if (Directory.Exists(_testRoot))
+        {
+            Directory.Delete(_testRoot, recursive: true);
+        }
+    }
+}