📝 clarify sync projection runtime helper state

docs/api/library-logger-to-logger.md

@@ -37,6 +37,7 @@ Detailed rules explaining key parameters and behaviors
 - Sink wiring, target, min level, timestamp behavior, and attached wrappers remain the same.
 - Use this when code needs full-surface APIs such as `with_timestamp(...)`, `with_filter(...)`, or `with_patch(...)`.
 - When the wrapped sink is `RuntimeSink`, unwrapping preserves that runtime sink value, but the result type is still `Logger[RuntimeSink]` rather than the `ConfiguredLogger` alias. Runtime-specific operations remain available through `full.sink` or by keeping a `ConfiguredLogger` value directly.
+- That same unwrap also preserves queued runtime state and file-backed helper behavior exactly as they existed behind the facade, including drain or flush results, file state snapshots, and file control methods.
 
 ### How to Use
 
@@ -71,6 +72,8 @@ e.g.:
 
 - Recovering the full logger does not rebuild or reset the existing sink wrappers.
 
+- Recovering the full logger does not translate configured runtime state into a simpler snapshot; queued counts, file availability, file failure counters, and runtime file controls stay exactly as they were on the wrapped logger.
+
 ### Notes
 
 1. Use this only when the narrower facade is no longer sufficient.