feat(usage): cache the TokenTracker export with single-flight refresh

tests/ClaudeDo.Worker.Tests/Usage/TokenTracker/FakeTokenTrackerClient.cs

@@ -0,0 +1,47 @@
+using ClaudeDo.Worker.Usage.TokenTracker;
+using ClaudeDo.Worker.Usage.TokenTracker.Interfaces;
+
+namespace ClaudeDo.Worker.Tests.Usage.TokenTracker;
+
+public sealed class FakeTokenTrackerClient : ITokenTrackerClient
+{
+    private readonly SemaphoreSlim _gate = new(0);
+
+    public TokenTrackerProbe Probe { get; set; } = new(true, "1.2.3", true, "v22.1.0", null);
+    public TokenTrackerRunResult ExportResult { get; set; } =
+        new(true, TokenTrackerFixtures.SessionsJson, null);
+    public TokenTrackerRunResult InstallResult { get; set; } = new(true, "added 1 package", null);
+
+    public int ExportCalls;
+    public int ProbeCalls;
+    public int InstallCalls;
+    public DateOnly? LastFrom;
+    public DateOnly? LastTo;
+
+    /// <summary>When true, <see cref="ExportAsync"/> blocks until <see cref="Release"/> is called.</summary>
+    public bool BlockExport { get; set; }
+
+    public void Release() => _gate.Release();
+
+    public Task<TokenTrackerProbe> ProbeAsync(CancellationToken ct = default)
+    {
+        Interlocked.Increment(ref ProbeCalls);
+        return Task.FromResult(Probe);
+    }
+
+    public async Task<TokenTrackerRunResult> ExportAsync(DateOnly from, DateOnly to, CancellationToken ct = default)
+    {
+        Interlocked.Increment(ref ExportCalls);
+        LastFrom = from;
+        LastTo = to;
+        if (BlockExport) await _gate.WaitAsync(ct);
+        return ExportResult;
+    }
+
+    public Task<TokenTrackerRunResult> InstallAsync(IProgress<string>? output = null, CancellationToken ct = default)
+    {
+        Interlocked.Increment(ref InstallCalls);
+        output?.Report("added 1 package");
+        return Task.FromResult(InstallResult);
+    }
+}

tests/ClaudeDo.Worker.Tests/Usage/TokenTracker/TokenTrackerServiceTests.cs

@@ -0,0 +1,138 @@
+using ClaudeDo.Worker.Usage.TokenTracker;
+
+namespace ClaudeDo.Worker.Tests.Usage.TokenTracker;
+
+public sealed class TokenTrackerServiceTests
+{
+    private static readonly DateTime Now = new(2026, 8, 24, 9, 0, 0, DateTimeKind.Utc);
+
+    private static (TokenTrackerService Service, FakeTokenTrackerClient Client) Build(DateTime? now = null)
+    {
+        var client = new FakeTokenTrackerClient();
+        var clock = now ?? Now;
+        return (new TokenTrackerService(client, new TokenTrackerState(), () => clock), client);
+    }
+
+    [Fact]
+    public async Task RefreshAsync_StoresParsedExport()
+    {
+        var (service, client) = Build();
+
+        await service.RefreshAsync();
+
+        Assert.Equal(1, client.ExportCalls);
+        Assert.Equal(4, service.State.Export!.Sessions.Count);
+        Assert.Null(service.State.LastError);
+    }
+
+    [Fact]
+    public async Task RefreshAsync_RequestsTheConfiguredWindow()
+    {
+        var (service, client) = Build();
+
+        await service.RefreshAsync();
+
+        Assert.Equal(DateOnly.FromDateTime(Now.ToLocalTime()), client.LastTo);
+        Assert.Equal(
+            DateOnly.FromDateTime(Now.ToLocalTime()).AddDays(-TokenTrackerService.WindowDays),
+            client.LastFrom);
+    }
+
+    [Fact]
+    public async Task RefreshAsync_Failure_KeepsLastGoodExport()
+    {
+        var (service, client) = Build();
+        await service.RefreshAsync();
+
+        client.ExportResult = new TokenTrackerRunResult(false, "", "tokentracker exited with code 1");
+        await service.RefreshAsync();
+
+        Assert.Equal(4, service.State.Export!.Sessions.Count);
+        Assert.Equal("tokentracker exited with code 1", service.State.LastError);
+    }
+
+    [Fact]
+    public async Task RefreshAsync_UnparseableOutput_IsAnError()
+    {
+        var (service, client) = Build();
+        client.ExportResult = new TokenTrackerRunResult(true, "not json", null);
+
+        await service.RefreshAsync();
+
+        Assert.Null(service.State.Export);
+        Assert.NotNull(service.State.LastError);
+    }
+
+    [Fact]
+    public async Task RefreshAsync_UnsupportedFormatVersion_IsAnErrorAndKeepsNoData()
+    {
+        var (service, client) = Build();
+        client.ExportResult = new TokenTrackerRunResult(true, TokenTrackerFixtures.UnsupportedVersionJson, null);
+
+        await service.RefreshAsync();
+
+        Assert.Null(service.State.Export);
+        Assert.Contains("99", service.State.LastError);
+    }
+
+    [Fact]
+    public async Task EnsureFreshAsync_FreshExport_DoesNotFetchAgain()
+    {
+        var (service, client) = Build();
+        await service.RefreshAsync();
+
+        await service.EnsureFreshAsync(TimeSpan.FromMinutes(15));
+
+        Assert.Equal(1, client.ExportCalls);
+    }
+
+    [Fact]
+    public async Task EnsureFreshAsync_NoExportYet_Fetches()
+    {
+        var (service, client) = Build();
+
+        await service.EnsureFreshAsync(TimeSpan.FromMinutes(15));
+
+        Assert.Equal(1, client.ExportCalls);
+    }
+
+    [Fact]
+    public async Task ConcurrentRefresh_RunsTheCliOnce()
+    {
+        var (service, client) = Build();
+        client.BlockExport = true;
+
+        var first = service.RefreshAsync();
+        var second = service.RefreshAsync();
+        client.Release();
+        await Task.WhenAll(first, second);
+
+        Assert.Equal(1, client.ExportCalls);
+    }
+
+    [Fact]
+    public async Task ProbeAsync_CachesUntilForced()
+    {
+        var (service, client) = Build();
+
+        await service.ProbeAsync();
+        await service.ProbeAsync();
+        Assert.Equal(1, client.ProbeCalls);
+
+        await service.ProbeAsync(force: true);
+        Assert.Equal(2, client.ProbeCalls);
+    }
+
+    [Fact]
+    public async Task InstallAsync_ReprobesAfterwards()
+    {
+        var (service, client) = Build();
+        await service.ProbeAsync();
+
+        var result = await service.InstallAsync();
+
+        Assert.True(result.Ok);
+        Assert.Equal(1, client.InstallCalls);
+        Assert.Equal(2, client.ProbeCalls);
+    }
+}