📝 Document 0.2 examples and usage patterns

docs/README-en.md

@@ -15,6 +15,17 @@ BitLogger currently provides:
 - optional timestamps via `with_timestamp()`
 - sink fanout via `fanout_sink(...)`
 - custom integration via `callback_sink(...)`
+- in-memory buffering via `buffered_sink(...)`
+- record filtering via `filter_sink(...)`
+- reusable filter helpers such as `target_has_prefix(...)`, `message_contains(...)`, `level_at_least(...)`, and `field_equals(...)`
+- record patching via `with_patch(...)` and `patch_sink(...)`
+- patch helpers such as `prefix_message(...)`, `append_fields(...)`, and `redact_fields(...)`
+- explicit queued delivery via `queued_sink(...)` and `with_queue(...)`
+- bounded backlog with `QueueOverflowPolicy::DropNewest` and `QueueOverflowPolicy::DropOldest`
+- configurable text formatting via `text_formatter(...)`, `format_text(...)`, and `text_console_sink(...)`
+- formatter-based callback integration via `formatted_callback_sink(...)`
+- native-only file output via `file_sink(...)`
+- `native_files_supported()` for backend capability detection
 - default global logger helpers
 
 ## Quick Start
@@ -47,6 +58,89 @@ let hook = Logger::new(
 hook.info("hello")
 ```
 
+Basic buffered sink:
+
+```moonbit
+let sink = buffered_sink(console_sink(), flush_limit=2)
+let logger = Logger::new(sink, target="buffered")
+
+logger.info("one")
+logger.info("two")
+sink.flush()
+```
+
+Basic filter sink:
+
+```moonbit
+let sink = filter_sink(console_sink(), fn(rec) {
+  rec.target == "kept"
+})
+
+let kept = Logger::new(sink, target="kept")
+let dropped = Logger::new(sink, target="dropped")
+
+kept.info("visible")
+dropped.info("hidden")
+```
+
+Chained logger filter:
+
+```moonbit
+let logger = Logger::new(console_sink(), target="service")
+  .with_filter(all_of([
+    target_has_prefix("service"),
+    message_contains("visible"),
+  ]))
+
+logger.info("hidden")
+logger.child("api").info("visible")
+```
+
+Record patching:
+
+```moonbit
+let logger = Logger::new(console_sink(), target="auth")
+  .with_patch(compose_patches([
+    prefix_message("[safe] "),
+    redact_fields(["token"]),
+    append_fields([field("service", "bitlogger")]),
+  ]))
+
+logger.info("login", fields=[field("user", "alice"), field("token", "secret")])
+```
+
+Explicit queued sink:
+
+```moonbit
+let logger = Logger::new(console_sink(), target="queue")
+  .with_queue(max_pending=2, overflow=QueueOverflowPolicy::DropOldest)
+
+logger.info("one")
+logger.info("two")
+logger.info("three")
+ignore(logger.sink.flush())
+```
+
+Custom text formatter:
+
+```moonbit
+let formatter = text_formatter(show_timestamp=false, separator=" | ")
+let logger = Logger::new(text_console_sink(formatter), target="pretty")
+
+logger.info("hello", fields=[field("mode", "pretty")])
+```
+
+Native file sink:
+
+```moonbit
+if native_files_supported() {
+  let logger = Logger::new(file_sink("bitlogger.log"), target="file")
+  logger.info("hello", fields=[field("kind", "file")])
+  ignore(logger.sink.flush())
+  ignore(logger.sink.close())
+}
+```
+
 ## Repository Layout
 
 - `bitlogger/`: MoonBit library package, tests, and Mooncake package README

docs/changes/0.2.0.md

@@ -0,0 +1,47 @@
+## BitLogger Update Changes
+
+version 0.2.0
+
+### Feature
+
+- feat: add `BufferedSink[S]` with in-memory buffering support
+- feat: add `buffered_sink(...)` constructor with configurable `flush_limit`
+- feat: add `BufferedSink::flush()` for manual drain
+- feat: add `BufferedSink::pending_count()` for buffer inspection in tests and integration code
+- feat: add `FilterSink[S]` for predicate-based record filtering
+- feat: add `filter_sink(...)` constructor for composable sink routing
+- feat: add `Logger::with_filter(...)` as a higher-level chained filter entry point
+- feat: add reusable filter helpers such as `target_is(...)`, `target_has_prefix(...)`, `message_contains(...)`, `level_at_least(...)`, `has_field(...)`, and `field_equals(...)`
+- feat: add predicate combinators `all_of(...)`, `any_of(...)`, and `not_(...)`
+- feat: add `PatchSink[S]`, `patch_sink(...)`, and `Logger::with_patch(...)` for record transformation
+- feat: add record patch helpers such as `prefix_message(...)`, `set_target(...)`, `append_fields(...)`, `redact_field(...)`, `redact_fields(...)`, and `compose_patches(...)`
+- feat: add `QueuedSink[S]`, `queued_sink(...)`, and `Logger::with_queue(...)` for explicit queued delivery
+- feat: add `QueueOverflowPolicy` with `DropNewest` and `DropOldest` bounded-backlog strategies
+- feat: add configurable text formatter APIs `text_formatter(...)`, `format_text(...)`, and `format_json(...)`
+- feat: add formatter-based sinks `formatted_console_sink(...)`, `text_console_sink(...)`, `formatted_callback_sink(...)`, and `text_callback_sink(...)`
+- feat: add native-only `file_sink(...)` plus `native_files_supported()` backend capability detection
+- feat: add explicit file sink lifecycle helpers `FileSink::is_available()`, `flush()`, and `close()`
+
+### Test
+
+- test: cover manual flush behavior for buffered sink
+- test: cover auto flush when buffered records reach the configured limit
+- test: cover predicate-based forwarding for filter sink
+- test: cover chained `Logger::with_filter(...)` behavior with child target composition
+- test: cover helper-based filter composition for target, level, message, and field matching
+- test: cover record patch composition, target rewrite, message rewrite, field append, and field redaction
+- test: cover queue drain order, bounded backlog drop behavior, and chained `Logger::with_queue(...)` usage
+- test: cover formatter customization, formatter-only message mode, formatted callback output, and JSON formatter shape
+- test: cover backend-aware file sink availability and lifecycle behavior
+- test: keep callback-based composition validation with child target, context fields, and timestamp enabled
+
+### Example
+
+- docs: update `examples/basic` to demonstrate buffered sink usage
+- docs: update `examples/basic` to demonstrate filter sink usage
+- docs: update examples and README with helper-based chained logger filter usage
+- docs: update examples and README with record patch usage for redaction and enrichment
+- docs: update examples and README with explicit queued sink usage and overflow policy examples
+- docs: update examples and README with configurable text formatter usage
+- docs: update examples and README with native file sink usage and backend caveat
+- docs: keep README focused on public usage and move change tracking to `docs/changes/`