📝 clarify built sync target behavior

docs/api/build-application-logger.md

@@ -37,6 +37,7 @@ Detailed rules explaining key parameters and behaviors
 - The embedded config still goes through the normal runtime logger build path, including runtime sink selection, optional queue wrapping, and timestamp application.
 - Because the result is only the `ApplicationLogger` alias over `ConfiguredLogger`, this builder does not hide any queue, drain, flush, or file runtime helper methods.
 - The returned alias also keeps inherited `Logger` behavior such as `with_target(...)`, `child(...)`, and per-call `target=` overrides on `log(...)`.
+- That means `log(..., target=...)` can override the target for one write, while severity helpers such as `info(...)`, `warn(...)`, and `error(...)` continue to use the stored logger target unless a derived logger was created first with `with_target(...)` or `child(...)`.
 - Use this alias-oriented entrypoint when application boot code wants an app-specific name without changing the underlying configured runtime logger surface.
 
 ### How to Use
@@ -58,6 +59,18 @@ And any queue/file/runtime helpers selected by the config remain directly availa
 
 The returned value also keeps the ordinary logger target semantics because the facade does not wrap or narrow the underlying `ConfiguredLogger`.
 
+#### When Need A Per-call Target Override After App-oriented Build
+
+When typed app config should still build a logger that supports a one-write target override:
+```moonbit
+let logger = build_application_logger(config)
+logger.log(Level::Error, "boom", target="app.audit")
+```
+
+In this example, the emitted record uses `app.audit` for that write.
+
+And later `info(...)`, `warn(...)`, or `error(...)` calls still use the logger's stored target unless code derives another logger first with `with_target(...)` or `child(...)`.
+
 ### Error Case
 
 e.g.:

docs/api/build-library-logger.md

@@ -37,6 +37,7 @@ Detailed rules explaining key parameters and behaviors
 - The embedded config still goes through the normal runtime logger build path, including runtime sink selection, optional queue wrapping, and timestamp application.
 - The returned facade wraps the same underlying `ConfiguredLogger` value that `build_logger(...)` would produce directly.
 - The facade intentionally exposes a smaller logging surface than the full configured runtime logger.
+- The facade still preserves the underlying logger target rules on its exposed write methods: `log(..., target=...)` can override the target for one write, while `info(...)`, `warn(...)`, and `error(...)` continue using the stored logger target unless the facade first derived another logger with `with_target(...)` or `child(...)`.
 - Queue metrics, flush and drain helpers, and file runtime controls remain on the underlying `ConfiguredLogger`, not on the returned facade itself.
 - Call `to_logger()` if a caller must recover the underlying full logger object.
 - Use this builder when the boundary should preserve the configured runtime logger path but still hide broader runtime helper methods from downstream callers.
@@ -69,6 +70,18 @@ In this example, the library facade is unwrapped before using runtime-specific h
 
 And the unwrapped value still carries the same `RuntimeSink` pipeline built from the original config.
 
+#### When Need A Per-call Target Override Through The Library Builder Facade
+
+When typed library config should still build a facade that allows a one-write target override without unwrapping first:
+```moonbit
+let logger = build_library_logger(config)
+logger.log(Level::Error, "boom", target="lib.audit")
+```
+
+In this example, the emitted record uses `lib.audit` for that write.
+
+And later `info(...)`, `warn(...)`, or `error(...)` calls still use the facade's stored target unless code derives another facade first with `with_target(...)` or `child(...)`.
+
 ### Error Case
 
 e.g.:

docs/api/build-logger.md

@@ -36,6 +36,7 @@ Detailed rules explaining key parameters and behaviors
 - `build_logger(...)` first constructs a base `RuntimeSink` from `config.sink`, then applies `config.queue` when present, and finally builds `Logger::new(...)` with `config.min_level`, `config.target`, and `config.timestamp`.
 - The returned logger still supports normal logging methods because `ConfiguredLogger` is `Logger[RuntimeSink]`.
 - The returned logger also keeps inherited logger target behavior such as `with_target(...)`, `child(...)`, and per-call `target=` overrides on `log(...)`.
+- That means `log(..., target=...)` can override the target for one write, while severity helpers such as `info(...)`, `warn(...)`, and `error(...)` continue to use the stored logger target unless a derived logger was created first with `with_target(...)` or `child(...)`.
 - Queue metrics and file controls remain available through forwarding helpers on the configured logger.
 - `build_application_logger(...)` only re-exports this same configured runtime logger result under the `ApplicationLogger` alias, while `build_library_logger(...)` wraps the same result in `LibraryLogger[RuntimeSink]`.
 - This API is deterministic and data-driven, making it suitable for bootstrapping from parsed config.
@@ -61,6 +62,18 @@ In this example, no JSON parsing is required because config objects were built d
 
 And the runtime logger is ready immediately, with the same ordinary logger target semantics as any other `Logger` value.
 
+#### When Need A Per-call Target Override After Typed Config Build
+
+When typed config should still build a logger that supports a one-write target override:
+```moonbit
+let logger = build_logger(config)
+logger.log(Level::Error, "boom", target="svc.audit")
+```
+
+In this example, the emitted record uses `svc.audit` for that write.
+
+And later `info(...)`, `warn(...)`, or `error(...)` calls still use the logger's stored target unless code derives another logger first with `with_target(...)` or `child(...)`.
+
 #### When Need Config-built Queue Or File Runtime Helpers
 
 When the sink shape comes from config but runtime controls still matter: