📝 Update More API Document

docs/api/build-library-logger.md

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+---
+name: build-library-logger
+group: api
+category: facade
+update-time: 20260520
+description: Build the library-facing sync logger facade from a LoggerConfig.
+key-word:
+    - library
+    - facade
+    - logger
+    - public
+---
+
+## Build-library-logger
+
+Build a `LibraryLogger[RuntimeSink]` from `LoggerConfig`. This facade keeps a smaller library-oriented sync surface while still using config-driven runtime assembly underneath.
+
+### Interface
+
+```moonbit
+pub fn build_library_logger(config : LoggerConfig) -> LibraryLogger[RuntimeSink] {
+```
+
+#### input
+
+- `config : LoggerConfig` - Fully assembled sync logger config.
+
+#### output
+
+- `LibraryLogger[RuntimeSink]` - Library-facing logger wrapper over the configured runtime sink.
+
+### Explanation
+
+Detailed rules explaining key parameters and behaviors
+
+- This API builds a configured runtime logger first and then wraps it as `LibraryLogger`.
+- The facade intentionally exposes a smaller logging surface than the full configured runtime logger.
+- Call `to_logger()` if a caller must recover the underlying full logger object.
+
+### How to Use
+
+Here are some specific examples provided.
+
+#### When Need A Smaller Library-facing Logging Type
+
+When package code should accept or produce a narrower logger facade:
+```moonbit
+let logger = build_library_logger(
+  LoggerConfig::new(target="lib", sink=SinkConfig::new(kind=SinkKind::Console)),
+)
+```
+
+In this example, the logger is built from config and then narrowed to the library facade.
+
+### Error Case
+
+e.g.:
+- If backend-specific sink limitations exist, they still apply after the facade is built.
+
+- If code later needs methods outside the library facade, it must unwrap with `to_logger()`.
+
+### Notes
+
+1. Prefer this facade when library APIs should not expose the full configured runtime logger type.
+
+2. Use `parse_and_build_library_logger(...)` when starting from JSON text.