[FreeApophis]

Closes #1004

Root cause

A continuation registered via OnCompleted/UnsafeOnCompleted on the awaiter of an already completed task is never invoked inline: Task.SetContinuationForAwait hands it to a scheduler. With a synchronization context installed that is the context (Post); without one it is the thread pool. Under xunit v2 the context is the MaxConcurrencySyncContext with one worker thread per core, and on the Windows runner dotnet test executes seven test hosts concurrently, so both schedulers are shared with every other test in the process and both were starved for more than the 5 s timeout:

• The original test (await Task.WhenAny(invoked.Task, Task.Delay(5 s))) waited for a continuation posted to xunit's context; the failures were always at the first line of each fact (the path without ConfigureAwait(false)), the failing Funcky.Async.Test run took 16 s instead of the usual 2–5 s.
• The first attempt in this PR cleared the context, which only moved the continuation to the thread pool; the CI run of that commit then timed out on Option<Task>.None.GetAwaiter().OnCompleted(...).

A synchronization context whose Post never runs its callbacks reproduces the original failure deterministically with the exact message; three full solution runs pinned to two cores did not trigger it naturally.

The library is correct and unchanged: all Option*Awaiter types forward OnCompleted and UnsafeOnCompleted 1:1 to the BCL awaiters. One asymmetry worth knowing: the generic awaiters (Option<Task<T>>, Option<ValueTask<T>>) hold an Option of the inner awaiter and invoke the continuation for None inline, whereas the non-generic ones (Option<Task>, Option<ValueTask>) replace None by Task.CompletedTask/default(ValueTask) and therefore schedule it like any completed task. The tests now document this.

Changes (Funcky.Test/Monads/OptionAwaiterTest.cs only)

No test waits on any scheduler any more; there are no timed waits left.

• None and completed Some (Task, Task, ValueTask, ValueTask, with and without ConfigureAwait(false)) assert IsCompleted and GetResult(). await only calls OnCompleted when IsCompleted is false, so registering on a completed awaiter is an artificial scenario.
• OnCompleted/UnsafeOnCompleted forwarding is tested on an incomplete task (TaskCompletionSource<T>, wrapped in a ValueTask/ValueTask<T> for those variants): the continuation is asserted not to have run, the source is completed on the test thread with the synchronization context cleared, where the BCL runs the await continuation inline within SetResult, and the invocation is asserted right after without waiting.
• A RecordingSynchronizationContext (runs posts inline, counts them) pins the context flow: completed Some and the non-generic None post exactly once, the generic None and every ConfigureAwait(false) path run inline, and ConfigureAwait(false) does not capture the context of the registration (the context is installed only while registering; the continuation then runs inline within SetResult).
• OptionOfIncompleteTaskIsAwaitable covers the await-based happy path for a task that completes after the await started.

Verification

dotnet build Funcky.slnx -warnaserror clean; Funcky.Test green on net10.0 and net4.8; Funcky.Async.Test green on net9.0 and net8.0.

🤖 Generated with Claude Code

[Copilot]

🟢 Approval recommended

The focused test-only changes restore synchronization contexts reliably and have no identified blocking issues.

No open issues 🎉

What changed in this PR

Addresses the flaky Option awaiter tests reported in #1004 by isolating continuation registration from xUnit’s synchronization context, without changing library behavior.

Changes:

• Registers continuations without a synchronization context and waits using ManualResetEventSlim.
• Adds tests for context capture, ConfigureAwait(false) bypass, and None continuations.
• Adds an await-based test for an initially incomplete task.

File	Description
Funcky.Test/​Monads/​OptionAwaiterTest.cs	Updates continuation test helpers and adds synchronization-context and incomplete-task coverage.

_{Review effort: Balanced}