fix(discord): add backoff to scheduler to prevent 403 spam

- SessionSchedulerService now backs off for 15 minutes after any handler failure (confirmation, one-hour reminder, join link), preventing infinite retry loops on Discord 403 Missing Access. - Added per-session ConcurrentDictionary backoff tracking with automatic cleanup on success. - Enhanced DiscordPlatformMessenger logging for SendConfirmation and SendJoinLink to aid permission diagnostics. - Added 3 regression tests for backoff behavior. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-26 15:51:25 +03:00
parent 9fc434b42b
commit a5aed14dd2
3 changed files with 171 additions and 21 deletions
@@ -149,6 +149,68 @@ public sealed class SessionSchedulerServiceTests
        Assert.Null(ex);
    }

+    [Fact]
+    public async Task TickAsync_WhenHandlerThrows_BackoffsForDuration()
+    {
+        var sessionId = Guid.NewGuid();
+        var now = new DateTimeOffset(2026, 5, 15, 10, 0, 0, TimeSpan.Zero);
+        _clock.UtcNow = now;
+        _store.SessionsNeedingConfirmation = [sessionId];
+        _confirmationHandler.ThrowFor.Add(sessionId);
+
+        var sut = CreateSut();
+        await sut.TickAsync(CancellationToken.None);
+        Assert.Single(_confirmationHandler.Calls);
+
+        // Second tick immediately — should be backed off
+        await sut.TickAsync(CancellationToken.None);
+        Assert.Single(_confirmationHandler.Calls);
+    }
+
+    [Fact]
+    public async Task TickAsync_WhenHandlerThrows_AfterBackoffRetriesAgain()
+    {
+        var sessionId = Guid.NewGuid();
+        var now = new DateTimeOffset(2026, 5, 15, 10, 0, 0, TimeSpan.Zero);
+        _clock.UtcNow = now;
+        _store.SessionsNeedingConfirmation = [sessionId];
+        _confirmationHandler.ThrowFor.Add(sessionId);
+
+        var sut = CreateSut();
+        await sut.TickAsync(CancellationToken.None);
+        Assert.Single(_confirmationHandler.Calls);
+
+        // Advance clock past backoff duration (15 min)
+        _clock.UtcNow = now.AddMinutes(16);
+        await sut.TickAsync(CancellationToken.None);
+        Assert.Equal(2, _confirmationHandler.Calls.Count);
+    }
+
+    [Fact]
+    public async Task TickAsync_WhenHandlerSucceedsAfterBackoff_ClearsBackoff()
+    {
+        var sessionId = Guid.NewGuid();
+        var now = new DateTimeOffset(2026, 5, 15, 10, 0, 0, TimeSpan.Zero);
+        _clock.UtcNow = now;
+        _store.SessionsNeedingConfirmation = [sessionId];
+        _confirmationHandler.ThrowFor.Add(sessionId);
+
+        var sut = CreateSut();
+        await sut.TickAsync(CancellationToken.None);
+        Assert.Single(_confirmationHandler.Calls);
+
+        // Remove throw condition, advance past backoff
+        _confirmationHandler.ThrowFor.Remove(sessionId);
+        _clock.UtcNow = now.AddMinutes(16);
+        await sut.TickAsync(CancellationToken.None);
+        Assert.Equal(2, _confirmationHandler.Calls.Count);
+
+        // Next tick should still call because backoff was cleared on success
+        _clock.UtcNow = now.AddMinutes(17);
+        await sut.TickAsync(CancellationToken.None);
+        Assert.Equal(3, _confirmationHandler.Calls.Count);
+    }
+
    private sealed class FakeSendConfirmationHandler : ISendConfirmationHandler
    {
        public List<Guid> Calls { get; } = [];