📝 Update More API Document

docs/api/default-library-logger.md

@@ -0,0 +1,63 @@
+---
+name: default-library-logger
+group: api
+category: facade
+update-time: 20260520
+description: Create the default library-facing console logger facade from shared global defaults.
+key-word:
+    - library
+    - facade
+    - default
+    - public
+---
+
+## Default-library-logger
+
+Create a `LibraryLogger[ConsoleSink]` from the current shared default console logger settings. This is the narrow library-facing counterpart to `default_logger()`.
+
+### Interface
+
+```moonbit
+pub fn default_library_logger() -> LibraryLogger[ConsoleSink] {
+```
+
+#### output
+
+- `LibraryLogger[ConsoleSink]` - Library-facing console logger built from the current shared defaults.
+
+### Explanation
+
+Detailed rules explaining key parameters and behaviors
+
+- This API wraps `default_logger()` as a library facade.
+- Each call reflects the current shared default minimum level and default target at that moment.
+- The returned value exposes the narrower `LibraryLogger` surface rather than the full `Logger` surface.
+
+### How to Use
+
+Here are some specific examples provided.
+
+#### When Need A Default Logger But Want A Narrower Facade
+
+When a library should adopt the shared console defaults without exposing the full logger type:
+```moonbit
+let logger = default_library_logger()
+if logger.is_enabled(Level::Info) {
+  logger.info("ready")
+}
+```
+
+In this example, the library facade mirrors the current global defaults.
+
+### Error Case
+
+e.g.:
+- If the shared default target is empty, the returned logger is still valid.
+
+- Later changes to shared defaults do not mutate an already-created facade value.
+
+### Notes
+
+1. Use `to_logger()` if callers need the full sync logger surface.
+
+2. This helper is useful for library-facing APIs that should stay narrower than `Logger`.