📝 Update More API Document

docs/api/build-library-async-logger.md

@@ -0,0 +1,71 @@
+---
+name: build-library-async-logger
+group: api
+category: facade
+update-time: 20260520
+description: Build the library-facing async logger facade from an AsyncLoggerBuildConfig.
+key-word:
+    - library
+    - async
+    - facade
+    - public
+---
+
+## Build-library-async-logger
+
+Build a `LibraryAsyncLogger[RuntimeSink]` from `AsyncLoggerBuildConfig`. This is the library-facing async facade over the general config-driven async builder.
+
+### Interface
+
+```moonbit
+pub fn build_library_async_logger(
+  config : AsyncLoggerBuildConfig,
+) -> LibraryAsyncLogger[RuntimeSink] {
+```
+
+#### input
+
+- `config : AsyncLoggerBuildConfig` - Combined sync logger config and async queue/runtime config.
+
+#### output
+
+- `LibraryAsyncLogger[RuntimeSink]` - Library-facing async logger wrapper.
+
+### Explanation
+
+Detailed rules explaining key parameters and behaviors
+
+- This API builds the general async runtime logger and then wraps it in the narrower `LibraryAsyncLogger` facade.
+- The result keeps async lifecycle operations such as `run()` and `shutdown()` while narrowing the public shape.
+- `to_async_logger()` can be used to recover the underlying full async logger.
+
+### How to Use
+
+Here are some specific examples provided.
+
+#### When Need A Narrower Async Type For Libraries
+
+When a reusable package should expose async logging but not the full runtime type directly:
+```moonbit
+let logger = build_library_async_logger(
+  AsyncLoggerBuildConfig::new(
+    logger=LoggerConfig::new(target="lib.async"),
+    async_config=AsyncLoggerConfig::new(max_pending=4),
+  ),
+)
+```
+
+In this example, async runtime construction is hidden behind the library facade.
+
+### Error Case
+
+e.g.:
+- If backend-specific sink limitations exist, they still apply under the facade.
+
+- If callers need methods outside the library facade, they must unwrap with `to_async_logger()`.
+
+### Notes
+
+1. Prefer this API when library boundaries should stay narrow.
+
+2. Use `parse_and_build_library_async_logger(...)` when starting from JSON text.