Task+Timeout.swift

extension Task where Failure == Error {

  // Start a new Task with a timeout. If the timeout expires before the operation is 
  // completed then the task is cancelled and an error is thrown.
  init(priority: TaskPriority? = nil, timeout: TimeInterval, operation: @escaping @Sendable () async throws -> Success) {
    self = Task(priority: priority) {
      try await withThrowingTaskGroup(of: Success.self) { group -> Success in
        group.addTask(operation: operation)
        group.addTask {
          try await _Concurrency.Task.sleep(nanoseconds: UInt64(timeout * 1_000_000_000))
          throw TimeoutError()
        }
        guard let success = try await group.next() else {
          throw _Concurrency.CancellationError()
        }
        group.cancelAll()
        return success
      }
    }
  }
}

private struct TimeoutError: LocalizedError {
  var errorDescription: String? = "Task timed out before completion"
}

Apple documentation is shit as usual. Thank you @swhitty & @MrDzmitry for the great discussion! It was a great learning resource for me on async/await.

A Swift 6 compatible version is available within the micro package swhitty/swift-timeout