diff --git a/src/ClaudeDo.Worker/Services/AgentFileService.cs b/src/ClaudeDo.Worker/Services/AgentFileService.cs
new file mode 100644
index 0000000..adc598a
--- /dev/null
+++ b/src/ClaudeDo.Worker/Services/AgentFileService.cs
@@ -0,0 +1,76 @@
+using ClaudeDo.Data.Models;
+
+namespace ClaudeDo.Worker.Services;
+
+public sealed class AgentFileService
+{
+    private readonly string _agentsDir;
+
+    public AgentFileService(string agentsDir)
+    {
+        _agentsDir = agentsDir;
+    }
+
+    public Task<List<AgentInfo>> ScanAsync(CancellationToken ct = default)
+    {
+        var agents = new List<AgentInfo>();
+        if (!Directory.Exists(_agentsDir))
+            return Task.FromResult(agents);
+
+        foreach (var file in Directory.EnumerateFiles(_agentsDir, "*.md"))
+        {
+            ct.ThrowIfCancellationRequested();
+            var (name, description) = ParseFrontmatter(file);
+            agents.Add(new AgentInfo(name, description, file));
+        }
+
+        agents.Sort((a, b) => string.Compare(a.Name, b.Name, StringComparison.OrdinalIgnoreCase));
+        return Task.FromResult(agents);
+    }
+
+    public async Task<string> ReadAsync(string path, CancellationToken ct = default)
+    {
+        return await File.ReadAllTextAsync(path, ct);
+    }
+
+    public async Task WriteAsync(string path, string content, CancellationToken ct = default)
+    {
+        var dir = Path.GetDirectoryName(path);
+        if (dir is not null) Directory.CreateDirectory(dir);
+        await File.WriteAllTextAsync(path, content, ct);
+    }
+
+    public Task DeleteAsync(string path, CancellationToken ct = default)
+    {
+        ct.ThrowIfCancellationRequested();
+        if (File.Exists(path)) File.Delete(path);
+        return Task.CompletedTask;
+    }
+
+    private static (string name, string description) ParseFrontmatter(string filePath)
+    {
+        var fileName = Path.GetFileNameWithoutExtension(filePath);
+        string name = fileName;
+        string description = "";
+
+        try
+        {
+            using var reader = new StreamReader(filePath);
+            var firstLine = reader.ReadLine();
+            if (firstLine?.Trim() != "---")
+                return (name, description);
+
+            while (reader.ReadLine() is { } line)
+            {
+                if (line.Trim() == "---") break;
+                if (line.StartsWith("name:"))
+                    name = line["name:".Length..].Trim();
+                else if (line.StartsWith("description:"))
+                    description = line["description:".Length..].Trim();
+            }
+        }
+        catch { /* Can't read file -- use filename fallback */ }
+
+        return (name, description);
+    }
+}
diff --git a/tests/ClaudeDo.Worker.Tests/Services/AgentFileServiceTests.cs b/tests/ClaudeDo.Worker.Tests/Services/AgentFileServiceTests.cs
new file mode 100644
index 0000000..d857da2
--- /dev/null
+++ b/tests/ClaudeDo.Worker.Tests/Services/AgentFileServiceTests.cs
@@ -0,0 +1,84 @@
+using ClaudeDo.Worker.Services;
+
+namespace ClaudeDo.Worker.Tests.Services;
+
+public sealed class AgentFileServiceTests : IDisposable
+{
+    private readonly string _agentDir;
+    private readonly AgentFileService _service;
+
+    public AgentFileServiceTests()
+    {
+        _agentDir = Path.Combine(Path.GetTempPath(), $"claudedo_agents_test_{Guid.NewGuid():N}");
+        Directory.CreateDirectory(_agentDir);
+        _service = new AgentFileService(_agentDir);
+    }
+
+    [Fact]
+    public async Task Scan_Returns_Empty_For_Empty_Directory()
+    {
+        var agents = await _service.ScanAsync();
+        Assert.Empty(agents);
+    }
+
+    [Fact]
+    public async Task Scan_Parses_Frontmatter()
+    {
+        var content = "---\nname: Test Agent\ndescription: A test agent for unit tests\n---\n\nYou are a test agent.";
+        await File.WriteAllTextAsync(Path.Combine(_agentDir, "test.md"), content);
+
+        var agents = await _service.ScanAsync();
+        Assert.Single(agents);
+        Assert.Equal("Test Agent", agents[0].Name);
+        Assert.Equal("A test agent for unit tests", agents[0].Description);
+        Assert.EndsWith("test.md", agents[0].Path);
+    }
+
+    [Fact]
+    public async Task Scan_Uses_Filename_When_No_Frontmatter()
+    {
+        await File.WriteAllTextAsync(Path.Combine(_agentDir, "simple.md"), "Just instructions.");
+
+        var agents = await _service.ScanAsync();
+        Assert.Single(agents);
+        Assert.Equal("simple", agents[0].Name);
+        Assert.Equal("", agents[0].Description);
+    }
+
+    [Fact]
+    public async Task Write_And_Read_Roundtrips()
+    {
+        var path = Path.Combine(_agentDir, "new-agent.md");
+        var content = "---\nname: New\ndescription: Desc\n---\nBody";
+        await _service.WriteAsync(path, content);
+
+        var read = await _service.ReadAsync(path);
+        Assert.Equal(content, read);
+    }
+
+    [Fact]
+    public async Task Delete_Removes_File()
+    {
+        var path = Path.Combine(_agentDir, "to-delete.md");
+        await File.WriteAllTextAsync(path, "temp");
+
+        await _service.DeleteAsync(path);
+        Assert.False(File.Exists(path));
+    }
+
+    [Fact]
+    public async Task Scan_Ignores_Non_Md_Files()
+    {
+        await File.WriteAllTextAsync(Path.Combine(_agentDir, "notes.txt"), "not an agent");
+        await File.WriteAllTextAsync(Path.Combine(_agentDir, "agent.md"), "---\nname: Real\ndescription: Yes\n---\nBody");
+
+        var agents = await _service.ScanAsync();
+        Assert.Single(agents);
+        Assert.Equal("Real", agents[0].Name);
+    }
+
+    public void Dispose()
+    {
+        try { Directory.Delete(_agentDir, true); } catch { }
+    }
+}