Several smaller issues were identified during the analysis:

1. Truncation in doubleToMillis: every nap is rounded down to whole milliseconds, so every queued waiter wakes up to 1ms early, systematically; rounding up would be strictly conservative.
2. Clock mixing: maturity is computed on the TickSource (monotonic), but the deadline is built on the passed ClockSource (wall clock for opCtx), so wall-clock jumps shift all sleepers together.
3. Overshoot baked into adjustedNapTime: the nap is computed against nowInSeconds() captured before the borrow, but _timeEnqueued is captured after enqueue and metrics, so every waiter oversleeps by the enqueue-path latency; storing the absolute maturity (debtPaid) in the DeferredToken would be cleaner and race-free.
4. Metrics: averageTimeQueuedMicros records the original _napTime rather than the actual wait on success, and is not recorded at all on the interrupt path, inconsistent with timeQueuedMicros.