Turns the Phase 6.1 Stream B.4 pure-logic ScheduledRecycleScheduler (shipped
in PR #79) into a running background feature. A Tier C driver registers its
scheduler at startup; the hosted service ticks every TickInterval (default
1 min) and invokes TickAsync on each registered scheduler.
Server.Hosting:
- ScheduledRecycleHostedService : BackgroundService. AddScheduler(s) must be
called before StartAsync — registering post-start throws
InvalidOperationException to avoid "some ticks saw my scheduler, some
didn't" races. ExecuteAsync loops on Task.Delay(TickInterval, _timeProvider,
stoppingToken) + delegates to a public TickOnceAsync method for one tick.
- TickOnceAsync extracted as the unit-of-work so tests drive it directly
without needing to synchronize with FakeTimeProvider + BackgroundService
timing semantics.
- Exception isolation: if one scheduler throws, the loop logs + continues
to the next scheduler. A flaky supervisor can't take down the tick for
every other Tier C driver.
- Diagnostics: TickCount + SchedulerCount properties for tests + logs.
Tests (7 new ScheduledRecycleHostedServiceTests, all pass):
- TickOnce before interval doesn't fire; TickCount still advances.
- TickOnce at/after interval fires the underlying scheduler exactly once.
- Multiple ticks accumulate count.
- AddScheduler after StartAsync throws.
- Throwing scheduler doesn't poison its neighbours (logs + continues).
- SchedulerCount matches registrations.
- Empty scheduler list ticks cleanly (no-op + counter advances).
Full solution dotnet test: 1193 passing (was 1186, +7). Pre-existing
Client.CLI Subscribe flake unchanged.
Production wiring (Program.cs):
builder.Services.AddSingleton<ScheduledRecycleHostedService>();
builder.Services.AddHostedService(sp => sp.GetRequiredService<ScheduledRecycleHostedService>());
// During DI configuration, once Tier C drivers + their ScheduledRecycleSchedulers
// are resolved, call host.AddScheduler(scheduler) for each.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
