feat: detect host operating system at startup and provide platform-specific guidance

MeetingAssistant.Tests/HealthEndpointTests.cs

@@ -41,6 +41,19 @@ public sealed class HealthEndpointTests : IClassFixture<WebApplicationFactory<Pr
         Assert.Equal("ok", body?.Status);
     }
 
+    [Fact]
+    public async Task ApplicationStartupRegistersDetectedHostOperatingSystemOnce()
+    {
+        using var client = factory.CreateClient();
+        using var response = await client.GetAsync("/health");
+        var first = factory.Services.GetRequiredService<HostOperatingSystem>();
+        var second = factory.Services.GetRequiredService<HostOperatingSystem>();
+
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        Assert.Same(first, second);
+        Assert.Equal(HostOperatingSystem.DetectCurrent(), first);
+    }
+
     [Fact]
     public async Task ApplicationStartupDeletesStaleTemporaryRecordings()
     {

MeetingAssistant.Tests/WorkflowRulesEditorTests.cs

@@ -732,6 +732,7 @@ public sealed class WorkflowRulesEditorTests
         var root = Path.Combine(Path.GetTempPath(), "meeting-assistant-tests", Guid.NewGuid().ToString("N"));
         var rulesPath = Path.Combine(root, "rules.yaml");
         var builder = new WorkflowRulesEditorInstructionBuilder(
+            HostOperatingSystem.DetectCurrent(),
             NullLogger<WorkflowRulesEditorInstructionBuilder>.Instance);
 
         var instructions = await builder.BuildAsync(new MeetingAssistantOptions
@@ -749,10 +750,61 @@ public sealed class WorkflowRulesEditorTests
         Assert.Contains("list_recent_summaries", instructions);
     }
 
+    [Fact]
+    public async Task InstructionBuilderUsesWindowsCommandsAndConceptsOnWindows()
+    {
+        var builder = new WorkflowRulesEditorInstructionBuilder(
+            new HostOperatingSystem(HostOperatingSystemKind.Windows),
+            NullLogger<WorkflowRulesEditorInstructionBuilder>.Instance);
+
+        var instructions = await builder.BuildAsync(new MeetingAssistantOptions(), CancellationToken.None);
+
+        Assert.Contains("Detected host operating system: Windows", instructions);
+        Assert.Contains("PowerShell", instructions);
+        Assert.Contains("Windows-style paths", instructions);
+        Assert.Contains("Windows services", instructions);
+        Assert.Contains("Task Manager", instructions);
+        Assert.Contains("Do not use macOS-only commands or concepts", instructions);
+        Assert.Contains("does not make unavailable integrations available", instructions);
+    }
+
+    [Fact]
+    public async Task InstructionBuilderUsesMacOSCommandsAndConceptsOnMacOS()
+    {
+        var builder = new WorkflowRulesEditorInstructionBuilder(
+            new HostOperatingSystem(HostOperatingSystemKind.MacOS),
+            NullLogger<WorkflowRulesEditorInstructionBuilder>.Instance);
+
+        var instructions = await builder.BuildAsync(new MeetingAssistantOptions(), CancellationToken.None);
+
+        Assert.Contains("Detected host operating system: macOS", instructions);
+        Assert.Contains("zsh", instructions);
+        Assert.Contains("POSIX-style paths", instructions);
+        Assert.Contains("launchd and LaunchAgents", instructions);
+        Assert.Contains("Activity Monitor", instructions);
+        Assert.Contains("Do not use Windows-only commands or concepts", instructions);
+        Assert.Contains("does not make unavailable integrations available", instructions);
+    }
+
+    [Fact]
+    public async Task InstructionBuilderUsesPortableConceptsOnUnsupportedHosts()
+    {
+        var builder = new WorkflowRulesEditorInstructionBuilder(
+            new HostOperatingSystem(HostOperatingSystemKind.Unsupported),
+            NullLogger<WorkflowRulesEditorInstructionBuilder>.Instance);
+
+        var instructions = await builder.BuildAsync(new MeetingAssistantOptions(), CancellationToken.None);
+
+        Assert.Contains("Detected host operating system: unsupported", instructions);
+        Assert.Contains("portable .NET concepts", instructions);
+        Assert.Contains("Do not assume Windows or macOS", instructions);
+    }
+
     [Fact]
     public async Task InstructionBuilderIncludesProjectSyncGuidanceForCorrectedMeetingNotes()
     {
         var builder = new WorkflowRulesEditorInstructionBuilder(
+            HostOperatingSystem.DetectCurrent(),
             NullLogger<WorkflowRulesEditorInstructionBuilder>.Instance);
 
         var instructions = await builder.BuildAsync(new MeetingAssistantOptions(), CancellationToken.None);
@@ -767,6 +819,7 @@ public sealed class WorkflowRulesEditorTests
     public async Task InstructionBuilderTreatsAssistantContextAsMeetingMemoryDuringRepairs()
     {
         var builder = new WorkflowRulesEditorInstructionBuilder(
+            new HostOperatingSystem(HostOperatingSystemKind.MacOS),
             NullLogger<WorkflowRulesEditorInstructionBuilder>.Instance);
         var options = new MeetingAssistantOptions
         {
@@ -784,6 +837,8 @@ public sealed class WorkflowRulesEditorTests
         Assert.Contains("read the matching assistant context", instructions);
         Assert.Contains("problems, missing information, assumptions, prior fixes, and conclusions", instructions);
         Assert.Contains("append a concise record of your fixes and conclusions", instructions);
+        Assert.Contains("Detected host operating system: macOS", instructions);
+        Assert.Contains("zsh", instructions);
     }
 
     [Fact]