Prepare 0.4.1 release documentation

docs/README-en.md

@@ -6,6 +6,15 @@ BitLogger is a structured logging library written in MoonBit.
 
 BitLogger currently provides:
 
+## Backend Compatibility
+
+| Module / capability | native / llvm | js / wasm / wasm-gc |
+| --- | --- | --- |
+| `bitlogger` core package | Supported | Supported |
+| `file_sink(...)` | Supported | Not available, `native_files_supported()` returns `false` |
+| `bitlogger_async` | Native worker semantics | Compatibility implementation |
+| `examples/async_basic` | Supported | Not shipped currently because `async fn main` entry support is still limited |
+
 - log levels: `Trace`, `Debug`, `Info`, `Warn`, `Error`
 - structured key-value fields
 - plain console output
@@ -331,8 +340,17 @@ match logger.file_runtime_state() {
 - `shutdown()` is now the recommended way to stop the async worker. By default it waits for the queue to drain, closes the queue, and then waits for the worker to exit.
 - Basic lifecycle observability is also available through `is_closed()`, `is_running()`, `has_failed()`, and `last_error()`.
 - The async worker now supports batched queue draining via `max_batch` and basic flush policies through `flush=Never|Batch|Shutdown`.
+- `async_runtime_mode()`, `async_runtime_mode_label(...)`, and `async_runtime_supports_background_worker()` expose whether the current backend is using the native worker path or the compatibility implementation.
+- `async_runtime_state_to_json(...)` and `stringify_async_runtime_state(...)` make it easy to include the current async runtime mode in startup diagnostics or health output.
 - The recommended startup pattern is shown in [examples/async_basic/main.mbt](/E:/repo/MooLiteyukiBot/examples/async_basic/main.mbt:1).
-- This layer currently targets `native/llvm` only and remains isolated from the synchronous logger core.
+- `bitlogger_async` now compiles across multiple targets: `native/llvm` keeps the background worker semantics, while `js` / `wasm` / `wasm-gc` use a compatibility implementation.
+- Because `moonbitlang/async` still limits `async fn main` entry support, the `examples/async_basic` executable remains `native`-only for now.
+
+Startup diagnostic example:
+
+```moonbit
+println(stringify_async_runtime_state(async_runtime_state(), pretty=true))
+```
 
 ### Async Config
 

docs/changes/0.4.0.md

@@ -3,7 +3,6 @@
 version 0.4.0
 
 ### Feature
-
 - feat: add `ColorMode = Never | Auto | Always` for text formatter color control
 - feat: add ANSI level, target, timestamp, and field rendering to `format_text(...)`
 - feat: add `color_mode` to `TextFormatter` and `TextFormatterConfig`
@@ -22,7 +21,6 @@ version 0.4.0
 - feat: add `ColorSupport = Basic | TrueColor` and support `sink.text_formatter.color_support` so hex / RGB styles can downgrade to basic ANSI colors
 
 ### Test
-
 - test: cover ANSI text formatter rendering in `Always` mode
 - test: cover `Auto` mode fallback behavior when `NO_COLOR` is present
 - test: cover config parsing and serialization for `color_mode`
@@ -43,7 +41,6 @@ version 0.4.0
 - docs: add runtime and JSON examples for toggling style markup parsing
 
 ### Notes
-
 - `Auto` currently uses a conservative rule: if `NO_COLOR` exists, ANSI is disabled; otherwise ANSI is enabled
 - inline style markup supports both short close `</>` and named closing tags like `</red>`
 - unknown or invalid inline tags currently fall back to plain text and do not raise formatter errors

docs/changes/0.4.1.md

@@ -0,0 +1,19 @@
+## BitLogger Update Changes
+
+version 0.4.1
+
+### Feature
+
+- feat: make `bitlogger_async` compile on `js` / `wasm` / `wasm-gc` via a compatibility backend instead of abort-only stubs
+- feat: add `async_runtime_mode()` and related helpers so callers can explicitly detect native-worker vs compatibility async behavior
+- feat: add `AsyncRuntimeState` JSON/stringify helpers for exposing async runtime mode in diagnostics
+
+### Test
+
+- test: cover async logger compatibility backend queue drain behavior and keep async config roundtrip available on non-native targets
+- test: cover async runtime capability helper consistency across backend-specific implementations
+
+### Notes
+
+- `bitlogger_async` now provides a compatibility implementation on non-native targets; the standalone async example remains `native`-only because `async fn main` entry support is still toolchain-limited
+- `examples/async_basic` now prints the current async runtime state at startup so downstream projects have a minimal diagnostic pattern to copy