🩹 harden file rotation failures

README.md

@@ -6,28 +6,51 @@ BitLogger 是一个使用 MoonBit 编写的结构化日志库，适合命令行
 - [English README](./docs/README-en.md)
 - [Wiki](https://bitlogger.naloveyuki.top)
 
-## 介绍
+## 从第一个日志到扩展能力
 
-BitLogger 提供统一的日志级别、目标名、结构化字段和可定制格式，既可以直接输出到控制台，也可以在 native 环境写入文件，并提供异步日志版本。
+BitLogger 的文档按使用路径组织：先完成一个可运行的日志输出，再按需进入文件、配置、异步和组合能力。API 文档保留为精确参考，不需要从 API 文件名开始阅读。
 
-## 快速开始
+### 1. 安装
 
-```moonbit
-let logger = build_logger(
-  text_console(
-    min_level=Level::Info,
-    target="demo",
-    text_formatter=TextFormatterConfig::new(show_timestamp=false, separator=" | "),
-  ),
-)
+从一个空项目开始：
 
-logger.info("starting", fields=[field("port", "8080")])
-ignore(logger.flush())
+```bash
+moon new log-demo
+cd log-demo
+moon add Nanaloveyuki/BitLogger@0.7.1
 ```
 
-推荐从 `console(...)`、`json_console(...)`、`text_console(...)`、`file(...)` 这几个入口开始，再按需配合 `with_queue(...)` 或 `with_file_rotation(...)`。
+### 2. 写入第一条结构化日志
 
-如果你需要自己组合 sink，比如 `fanout`、`split`、`callback`，再使用 `Logger::new(...)`。
+在应用 package 的 `moon.pkg` 中导入库：
+
+```moonbit
+import {
+  "Nanaloveyuki/BitLogger/src" @log,
+}
+```
+
+然后在 `main.mbt` 中创建控制台 logger：
+
+```moonbit
+fn main {
+  let logger = @log.build_logger(
+    @log.console(min_level=@log.Level::Info, target="app"),
+  )
+
+  logger.info("server started", fields=[
+    @log.field("port", "8080"),
+    @log.field("environment", "development"),
+  ])
+}
+```
+
+运行 `moon run` 后，记录会携带 level、target、message 和 fields。下一步按实际需求选择：
+
+- [控制台与结构化字段](./docs/examples/console.md)
+- [文件输出与轮转](./docs/examples/file-rotation.md)
+- [JSON 配置构建](./docs/examples/config.md)
+- [异步日志生命周期](./docs/examples/async.md)
 
 ## 支持情况
 
@@ -47,19 +70,11 @@ ignore(logger.flush())
 - 组合能力：queue、filter、patch、fanout、split、callback
 - 异步日志：独立 `src-async` package
 
-## 示例
-
-- `examples/console_basic/`：最小 console / json console 示例
-- `examples/text_formatter/`：文本格式与模板示例
-- `examples/style_tags/`：style tag 与彩色输出示例
-- `examples/config_build/`：配置构建示例
-- `examples/presets/`：常用预设组合示例
-- `examples/file_rotation/`：文件输出与轮转示例，仅适用于 native
-- `examples/async_basic/`：异步日志示例
-
 ## 文档
 
-- [API 索引](./docs/api/index.md)
+- [Examples：完整使用流程](./docs/examples/index.md)
+- [Extend：队列、组合、格式化和跨端边界](./docs/extend/index.md)
+- [API 索引：按公开符号查询](./docs/api/index.md)
 - [src package README](./src/README.mbt.md)
 
-常用入口：`text_console(...)`、`file(...)`、`with_queue(...)`、`build_logger(...)`、`build_async_logger(...)`
+仓库内的 `examples/` 目录与 Examples 文档一一对应；文档解释选择、前提、运行命令和后续扩展，源码保持为可执行参考。

docs/.vitepress/config.mts

@@ -104,6 +104,117 @@ function buildChangesSidebar(): DefaultTheme.SidebarItem[] {
   ]
 }
 
+function buildExamplesSidebar(): DefaultTheme.SidebarItem[] {
+  return [
+    { text: 'Overview', link: '/examples/' },
+    { text: 'Console And Fields', link: '/examples/console' },
+    { text: 'File Rotation', link: '/examples/file-rotation' },
+    { text: 'Configuration', link: '/examples/config' },
+    { text: 'Async Lifecycle', link: '/examples/async' },
+  ]
+}
+
+function buildExtendSidebar(): DefaultTheme.SidebarItem[] {
+  return [
+    { text: 'Overview', link: '/extend/' },
+    { text: 'Queueing', link: '/extend/queue' },
+    { text: 'Sink Composition', link: '/extend/composition' },
+    { text: 'Text Formatting', link: '/extend/formatting' },
+    { text: 'Target Boundaries', link: '/extend/targets' },
+  ]
+}
+
+function buildChineseExamplesSidebar(): DefaultTheme.SidebarItem[] {
+  return [
+    { text: '概览', link: '/zh/examples/' },
+    { text: '控制台与结构化字段', link: '/zh/examples/console' },
+    { text: '文件输出与轮转', link: '/zh/examples/file-rotation' },
+    { text: '配置驱动构建', link: '/zh/examples/config' },
+    { text: '异步日志生命周期', link: '/zh/examples/async' },
+  ]
+}
+
+function buildChineseExtendSidebar(): DefaultTheme.SidebarItem[] {
+  return [
+    { text: '概览', link: '/zh/extend/' },
+    { text: '队列与溢出策略', link: '/zh/extend/queue' },
+    { text: 'Sink 组合', link: '/zh/extend/composition' },
+    { text: '文本格式与样式', link: '/zh/extend/formatting' },
+    { text: '目标平台边界', link: '/zh/extend/targets' },
+  ]
+}
+
+function buildChineseApiSidebar(): DefaultTheme.SidebarItem[] {
+  return [
+    { text: '概览', link: '/zh/api/' },
+    { text: '基础记录', link: '/zh/api/basics' },
+    { text: '配置与队列', link: '/zh/api/configuration' },
+    { text: '文件输出', link: '/zh/api/file-output' },
+    { text: '文本格式', link: '/zh/api/formatting' },
+    { text: '异步生命周期', link: '/zh/api/async' },
+    { text: 'Sink 组合', link: '/zh/api/composition' },
+  ]
+}
+
+const englishThemeConfig: DefaultTheme.Config = {
+  siteTitle: 'BitLogger',
+  nav: [
+    { text: 'Home', link: '/' },
+    { text: 'Examples', link: '/examples/' },
+    { text: 'Extend', link: '/extend/' },
+    { text: 'API', link: '/api/' },
+    { text: 'Changes', link: '/changes/' },
+    { text: 'Mooncake', link: 'https://mooncakes.io/docs/Nanaloveyuki/BitLogger' },
+  ],
+  search: {
+    provider: 'local',
+  },
+  socialLinks: [{ icon: 'github', link: repository }],
+  editLink: {
+    pattern: `${repository}/edit/main/docs/:path`,
+    text: 'Edit this page on GitHub',
+  },
+  sidebar: {
+    '/examples/': buildExamplesSidebar(),
+    '/extend/': buildExtendSidebar(),
+    '/api/': buildApiSidebar(),
+    '/changes/': buildChangesSidebar(),
+  },
+  footer: {
+    message: 'Published from the repository docs folder with VitePress.',
+    copyright: 'MIT',
+  },
+}
+
+const chineseThemeConfig: DefaultTheme.Config = {
+  siteTitle: 'BitLogger',
+  nav: [
+    { text: '首页', link: '/zh/' },
+    { text: '示例', link: '/zh/examples/' },
+    { text: '扩展', link: '/zh/extend/' },
+    { text: 'API', link: '/zh/api/' },
+    { text: '更新记录（英文）', link: '/changes/' },
+    { text: 'Mooncake', link: 'https://mooncakes.io/docs/Nanaloveyuki/BitLogger' },
+  ],
+  search: {
+    provider: 'local',
+  },
+  socialLinks: [{ icon: 'github', link: repository }],
+  editLink: {
+    pattern: `${repository}/edit/main/docs/:path`,
+    text: '在 GitHub 上编辑此页',
+  },
+  sidebar: {
+    '/zh/examples/': buildChineseExamplesSidebar(),
+    '/zh/extend/': buildChineseExtendSidebar(),
+    '/zh/api/': buildChineseApiSidebar(),
+  },
+  footer: {
+    message: '由仓库中的 VitePress 文档构建。',
+    copyright: 'MIT',
+  },
+}
+
 export default defineConfig({
   title: 'BitLogger',
   description: 'Structured logging library docs for MoonBit.',
@@ -114,29 +225,18 @@ export default defineConfig({
   markdown: {
     languages: [createMoonbitLanguageRegistration()],
   },
-  themeConfig: {
-    siteTitle: 'BitLogger',
-    nav: [
-      { text: 'Home', link: '/' },
-      { text: 'API', link: '/api/' },
-      { text: 'Changes', link: '/changes/' },
-      { text: 'Mooncake', link: 'https://mooncakes.io/docs/Nanaloveyuki/BitLogger' },
-    ],
-    search: {
-      provider: 'local',
+  themeConfig: englishThemeConfig,
+  locales: {
+    root: {
+      label: 'English',
+      lang: 'en-US',
+      themeConfig: englishThemeConfig,
     },
-    socialLinks: [{ icon: 'github', link: repository }],
-    editLink: {
-      pattern: `${repository}/edit/main/docs/:path`,
-      text: 'Edit this page on GitHub',
-    },
-    sidebar: {
-      '/api/': buildApiSidebar(),
-      '/changes/': buildChangesSidebar(),
-    },
-    footer: {
-      message: 'Published from the repository docs folder with VitePress.',
-      copyright: 'MIT',
+    zh: {
+      label: '简体中文',
+      lang: 'zh-CN',
+      link: '/zh/',
+      themeConfig: chineseThemeConfig,
     },
   },
 })

docs/.vitepress/theme/index.ts

@@ -6,11 +6,46 @@ import HomeDocHub from './components/HomeDocHub.vue'
 
 import './custom.css'
 
+const localePreferenceKey = 'bitlogger-docs-locale'
+
+function routePath(path: string): string {
+  return path.split(/[?#]/, 1)[0]
+}
+
+function isLocaleRoot(path: string): boolean {
+  const normalized = routePath(path)
+  return normalized === '/' || normalized === '/zh/'
+}
+
+function browserPrefersChinese(): boolean {
+  return navigator.languages.some(language => language.toLowerCase().startsWith('zh'))
+}
+
 const theme: Theme = {
   extends: DefaultTheme,
-  enhanceApp({ app }) {
+  enhanceApp({ app, router }) {
     app.component('ApiOverview', ApiOverview)
     app.component('HomeDocHub', HomeDocHub)
+
+    if (typeof window === 'undefined') return
+
+    router.onAfterRouteChange = to => {
+      if (!isLocaleRoot(to)) return
+      window.localStorage.setItem(localePreferenceKey, routePath(to) === '/zh/' ? 'zh' : 'en')
+    }
+
+    if (router.route.path !== '/') return
+
+    const savedLocale = window.localStorage.getItem(localePreferenceKey)
+    const locale = savedLocale === 'zh' || savedLocale === 'en'
+      ? savedLocale
+      : browserPrefersChinese()
+        ? 'zh'
+        : 'en'
+
+    if (locale === 'zh') {
+      void router.go('/zh/')
+    }
   },
 }
 

docs/README-en.md

@@ -9,24 +9,38 @@ BitLogger is a structured logging library for MoonBit projects.
 
 BitLogger gives you consistent levels, targets, structured fields, configurable text output, native file logging, and an async logging layer.
 
-## Quick Start
+## Start With A Working Flow
 
-```moonbit
-let logger = build_logger(
-  text_console(
-    min_level=Level::Info,
-    target="demo",
-    text_formatter=TextFormatterConfig::new(show_timestamp=false, separator=" | "),
-  ),
-)
+The documentation is organized around complete usage flows. Start with an executable logger, then move into file output, configuration, async lifecycle, and extensions. The API reference remains the precise symbol-level reference.
 
-logger.info("starting", fields=[field("port", "8080")])
-ignore(logger.flush())
+### 1. Install
+
+```bash
+moon new log-demo
+cd log-demo
+moon add Nanaloveyuki/BitLogger@0.7.1
 ```
 
-Start with `console(...)`, `json_console(...)`, `text_console(...)`, or `file(...)`, then add `with_queue(...)` or `with_file_rotation(...)` only when needed.
+### 2. Import And Log
 
-Use `Logger::new(...)` when you want to assemble custom sink graphs directly.
+Add the package import to your application's `moon.pkg`:
+
+```moonbit
+import {
+  "Nanaloveyuki/BitLogger/src" @log,
+}
+```
+
+```moonbit
+fn main {
+  let logger = @log.build_logger(
+    @log.console(min_level=@log.Level::Info, target="app"),
+  )
+  logger.info("server started", fields=[@log.field("port", "8080")])
+}
+```
+
+Continue with the [Examples guide](./examples/index.md): console fields, file rotation, JSON configuration, and async lifecycle are each documented as a complete path.
 
 ## Support Status
 
@@ -45,18 +59,10 @@ Use `Logger::new(...)` when you want to assemble custom sink graphs directly.
 - Composition helpers: queue, filter, patch, fanout, split, callback
 - Separate async package under `src-async`
 
-## Examples
-
-- `examples/console_basic/`: minimal console and JSON console example
-- `examples/text_formatter/`: text formatting and template example
-- `examples/style_tags/`: style tags and colored output example
-- `examples/config_build/`: config-based build example
-- `examples/presets/`: common preset combinations
-- `examples/file_rotation/`: native file logging and rotation example
-- `examples/async_basic/`: async logging example
-
 ## Documentation
 
+- [Examples](./examples/index.md): complete application-facing usage flows
+- [Extend](./extend/index.md): queueing, sink composition, formatting, and target boundaries
 - [API index](./api/index.md): canonical API reference, organized as one public API per file
 - [src package README](https://github.com/Nanaloveyuki/BitLogger/blob/main/src/README.mbt.md): package-level usage notes and target reminders
 - [`docs/changes/`](./changes/): versioned release notes and publish-facing change summaries

docs/api/file-sink-reopen-append.md

@@ -2,7 +2,7 @@
 name: file-sink-reopen-append
 group: api
 category: sink
-update-time: 20260613
+update-time: 20260717
 description: Reopen a FileSink in append mode.
 key-word:
     - file
@@ -37,6 +37,7 @@ Detailed rules explaining key parameters and behaviors
 - Reopen behavior is fixed to append mode.
 - The stored append policy is updated to `true` as part of the reopen path.
 - On failure, the sink remains unavailable and `open_failures` is incremented.
+- After a rotation failure, this is the explicit recovery path once the underlying remove, rename, or open condition has been resolved.
 
 ### How to Use
 

docs/api/file-sink-rotation-failures.md

@@ -2,7 +2,7 @@
 name: file-sink-rotation-failures
 group: api
 category: sink
-update-time: 20260707
+update-time: 20260717
 description: Read the number of rotation failures recorded by a FileSink.
 key-word:
     - file
@@ -36,6 +36,7 @@ Detailed rules explaining key parameters and behaviors
 - The sink reports its recorded rotation-failure count directly.
 - The counter increases when a rotation attempt cannot complete its critical file steps, such as removing the active file with zero backups, renaming a live file into `.1`, shifting an existing backup to a higher slot, or reopening the fresh active file afterward.
 - Missing optional backup slots do not count by themselves; only steps that fail while their source path still exists are treated as rotation failures.
+- When a critical rotation step fails, the triggering record is not written and the sink remains unavailable until an explicit reopen succeeds.
 - The counter is cumulative until reset.
 - This helper is observation-only and does not mutate sink state.
 
@@ -70,6 +71,8 @@ e.g.:
 
 - This counter alone does not say whether the sink is currently available.
 
+- After a recorded rotation failure, use `reopen_append()` only after the underlying filesystem condition has been resolved.
+
 ### Notes
 
 1. Use this helper when diagnosing incomplete direct file rotations.

docs/changes/1.1.1(0.7.1).md

@@ -0,0 +1,26 @@
+## BitLogger Update Changes
+
+version 1.1.1(0.7.1)
+
+### Toolchain
+
+- fix: migrate runnable example packages to `pkgtype(kind: "executable")` for MoonBit 0.10.4 formatter compatibility
+- fix: replace ambiguous empty map literals with `Map([])` so `--deny-warn` checks remain clean on MoonBit 0.10.4
+
+### Test
+
+- test: write file-backed test output under `logs/` instead of the repository root
+- test: keep the tracked `logs/.gitkeep` directory available for clean test checkouts
+
+### Docs
+
+- docs: update installation snippets to `Nanaloveyuki/BitLogger@0.7.1`
+- docs: add this 1.1.1(0.7.1) release entry to the change index
+
+### Verification
+
+- verify: pass formatting, warning-denied checks, synchronous and async cross-target tests, examples, and coverage on MoonBit 0.10.4
+
+### Notes
+
+- this is a compatibility and test-output maintenance release with no public API changes

docs/changes/index.md

@@ -2,6 +2,7 @@
 
 Versioned BitLogger change summaries.
 
+- [1.1.1](./1.1.1(0.7.1).md)
 - [1.1.0](./1.1.0(0.7.0).md)
 - [1.0.1](./1.0.1(0.6.1).md)
 - [1.0.0](./1.0.0(0.6.0).md)

docs/examples/async.md

@@ -0,0 +1,47 @@
+# Async Logger Lifecycle
+
+Use the async package when a native application needs logging to run through an async queue. The library supports broader targets, but the shipped `async fn main` example is native-focused.
+
+## Import Both Packages
+
+```moonbit
+import {
+  "Nanaloveyuki/BitLogger/src" @log,
+  "Nanaloveyuki/BitLogger/src-async" @async_log,
+  "moonbitlang/async",
+}
+```
+
+## Build, Run, Then Shut Down
+
+```moonbit
+async fn main {
+  let raw = "{\"logger\":{\"min_level\":\"info\",\"target\":\"service.async\",\"sink\":{\"kind\":\"text_console\"}},\"async_config\":{\"max_pending\":64,\"overflow\":\"DropOldest\",\"max_batch\":16,\"linger_ms\":5,\"flush\":\"Batch\"}}"
+  let config = @async_log.parse_async_logger_build_config_text(raw) catch {
+    err => {
+      ignore(err)
+      return
+    }
+  }
+  let logger = @async_log.build_async_logger(config)
+
+  @async.with_task_group(group => {
+    group.spawn_bg(allow_failure=true, () => logger.run())
+    logger.info("worker started", fields=[@log.field("mode", "async")])
+    logger.shutdown()
+  })
+}
+```
+
+`run()` owns the worker loop. Start it before producing records, then call `shutdown()` so pending work can follow the configured flush policy.
+
+## Run The Repository Example
+
+```bash
+moon run examples/async_basic --target native
+```
+
+## Next Steps
+
+- Inspect queue policy and flush choices in [Queueing](../extend/queue.md).
+- Reference: [`parse_async_logger_build_config_text(...)`](../api/parse-async-logger-build-config-text.md), [`build_async_logger(...)`](../api/build-async-logger.md), [`run()`](../api/async-logger-run.md), and [`shutdown()`](../api/async-logger-shutdown.md).

docs/examples/config.md

@@ -0,0 +1,35 @@
+# Configuration-Driven Logging
+
+Use configuration when deployment should select levels, output, formatting, or queue behavior without changing application code.
+
+## Parse, Build, Then Log
+
+```moonbit
+let raw = "{\"min_level\":\"info\",\"target\":\"service\",\"sink\":{\"kind\":\"text_console\",\"text_formatter\":{\"show_timestamp\":false,\"separator\":\" | \"}},\"queue\":{\"max_pending\":64,\"overflow\":\"DropOldest\"}}"
+
+let config = @log.parse_logger_config_text(raw) catch {
+  err => {
+    ignore(err)
+    println("invalid logger configuration")
+    return
+  }
+}
+
+let logger = @log.build_logger(config)
+logger.info("configured logger ready")
+ignore(logger.flush())
+```
+
+Parsing validates the data before runtime construction. Keep the raw configuration outside application code in a real deployment, but handle parsing errors at the boundary where configuration enters the process.
+
+## Run The Repository Example
+
+```bash
+moon run examples/config_build
+```
+
+## Next Steps
+
+- Use [Queueing](../extend/queue.md) to choose overflow behavior deliberately.
+- Use [Async lifecycle](./async.md) when the queue needs a background worker.
+- Reference: [`parse_logger_config_text(...)`](../api/parse-logger-config-text.md), [`build_logger(...)`](../api/build-logger.md), and [`with_queue(...)`](../api/with-queue.md).

docs/examples/console.md

@@ -0,0 +1,51 @@
+# Console And Structured Fields
+
+Use this flow for command-line tools and services that need a human-readable starting point. A record always has a level, target, message, and optional fields.
+
+## Install And Import
+
+```bash
+moon add Nanaloveyuki/BitLogger@0.7.1
+```
+
+```moonbit
+import {
+  "Nanaloveyuki/BitLogger/src" @log,
+}
+```
+
+## Build A Console Logger
+
+```moonbit
+fn main {
+  let logger = @log.build_logger(
+    @log.console(min_level=@log.Level::Info, target="service.http"),
+  )
+
+  logger.info("listening", fields=[
+    @log.field("port", "8080"),
+    @log.field("environment", "development"),
+  ])
+  logger.warn("slow request", fields=[@log.field("path", "/health")])
+}
+```
+
+`min_level` filters records before they reach the sink. `target` identifies the subsystem, while fields carry queryable context without interpolating it into the message.
+
+## Switch To JSON
+
+Keep the logging calls unchanged and replace the preset:
+
+```moonbit
+let logger = @log.build_logger(
+  @log.json_console(min_level=@log.Level::Info, target="service.http"),
+)
+```
+
+This is the preferred output for a collector that consumes one structured record per line.
+
+## Next Steps
+
+- Use [Text formatting](../extend/formatting.md) for a custom terminal format.
+- Use [Configuration](./config.md) when levels, targets, and sinks come from JSON.
+- Reference: [`console(...)`](../api/console.md), [`json_console(...)`](../api/json-console.md), [`field(...)`](../api/field.md), and [`build_logger(...)`](../api/build-logger.md).

docs/examples/file-rotation.md

@@ -0,0 +1,51 @@
+# File Output And Rotation
+
+File output is for native applications that need local persistence. Treat it as a native-only capability and keep a console fallback for portable code.
+
+## Check The Capability
+
+```moonbit
+if !@log.native_files_supported() {
+  println("file logging is unavailable on this target")
+  return
+}
+```
+
+## Build A Rotating File Logger
+
+```moonbit
+let config = @log.with_file_rotation(
+  @log.file(
+    "service.log",
+    min_level=@log.Level::Info,
+    target="service.file",
+    auto_flush=true,
+  ) catch {
+    err => {
+      ignore(err)
+      return
+    }
+  },
+  1024 * 1024,
+  max_backups=3,
+)
+
+let logger = @log.build_logger(config)
+logger.info("file logger ready")
+ignore(logger.flush())
+ignore(logger.file_close())
+```
+
+The rotation limit is the size of the active file in bytes. `max_backups=3` retains the rotated backup chain. Always close a file-backed logger during orderly application shutdown.
+
+## Run The Repository Example
+
+```bash
+moon run examples/file_rotation --target native
+```
+
+## Next Steps
+
+- Add a bounded queue with [Queueing](../extend/queue.md) when bursts should not write synchronously.
+- Read [Target boundaries](../extend/targets.md) before sharing the same logging setup with web targets.
+- Reference: [`file(...)`](../api/file.md), [`with_file_rotation(...)`](../api/with-file-rotation.md), and [`file_close(...)`](../api/configured-logger-file-close.md).

docs/examples/index.md

@@ -0,0 +1,24 @@
+# Examples
+
+Examples are the primary BitLogger learning path. Each page starts from an application concern, shows the complete minimum code, and then points to the API reference for exact contracts.
+
+## Choose A Flow
+
+| Need | Start here | Then extend with |
+| --- | --- | --- |
+| Print structured logs to a terminal | [Console and fields](./console.md) | [Text formatting](../extend/formatting.md) |
+| Keep local logs with bounded disk use | [File rotation](./file-rotation.md) | [Target boundaries](../extend/targets.md) |
+| Build logging from app configuration | [Configuration](./config.md) | [Queueing](../extend/queue.md) |
+| Avoid blocking a native application on writes | [Async lifecycle](./async.md) | [Sink composition](../extend/composition.md) |
+
+## Repository Examples
+
+The runnable sources live under `examples/`. The guides below explain their intended use instead of duplicating every API detail:
+
+- `examples/console_basic` for terminal and JSON records
+- `examples/config_build` for parsed configuration
+- `examples/file_rotation` for native file output
+- `examples/async_basic` for the async lifecycle
+- `examples/presets`, `examples/text_formatter`, and `examples/style_tags` for follow-on customization
+
+Use the [API reference](../api/index.md) when a guide links to a symbol and you need its full signature or edge-case behavior.

docs/extend/composition.md

@@ -0,0 +1,42 @@
+# Sink Composition
+
+Presets cover common console and file configurations. Build a `Logger::new(...)` directly when records need routing or multiple outputs.
+
+## Send A Record To Two Destinations
+
+```moonbit
+let logger = @log.Logger::new(
+  @log.fanout_sink(@log.console_sink(), @log.json_console_sink()),
+  min_level=@log.Level::Info,
+  target="service",
+)
+
+logger.info("request complete", fields=[@log.field("status", "200")])
+```
+
+`fanout_sink(...)` writes the same record to every child sink. This keeps human-oriented terminal output and machine-oriented JSON output in one application path.
+
+## Route Warnings Separately
+
+```moonbit
+let logger = @log.Logger::new(
+  @log.split_by_level(
+    @log.callback_sink(fn(rec) {
+      println("alert: \{rec.message}")
+    }),
+    @log.console_sink(),
+    min_level=@log.Level::Warn,
+  ),
+  min_level=@log.Level::Trace,
+  target="service",
+)
+```
+
+Use direct sink composition only when the routing behavior is part of the application design. A preset remains easier to audit when one sink is sufficient.
+
+## API Reference
+
+- [`Logger::new(...)`](../api/logger-new.md)
+- [`fanout_sink(...)`](../api/fanout-sink.md)
+- [`split_by_level(...)`](../api/split-by-level.md)
+- [`callback_sink(...)`](../api/callback-sink.md)

docs/extend/formatting.md

@@ -0,0 +1,44 @@
+# Text Formatting And Style Tags
+
+Formatting changes presentation while keeping the record's level, target, message, and fields intact. Use text output for people; use JSON output when another system parses the record.
+
+## Customize The Text Shape
+
+```moonbit
+let logger = @log.build_logger(
+  @log.text_console(
+    min_level=@log.Level::Info,
+    target="service",
+    text_formatter=@log.TextFormatterConfig::new(
+      show_timestamp=false,
+      field_separator=",",
+      template="[{level}] {target} {message} :: {fields}",
+    ),
+  ),
+)
+
+logger.info("ready", fields=[@log.field("port", "8080")])
+```
+
+The template controls the visible order. Keep fields separate from the message so they can still be rendered consistently across sinks.
+
+## Add Named Styles
+
+```moonbit
+let formatter = @log.text_formatter(
+  show_timestamp=false,
+  color_mode=@log.ColorMode::Always,
+).with_style_tags(
+  @log.default_style_tag_registry()
+  .set_tag("accent", fg=Some("#4cc9f0"), bold=true),
+)
+```
+
+Style tags are terminal presentation metadata. Do not use them as the only way to encode operational meaning; preserve that meaning in level, target, and fields.
+
+## API Reference
+
+- [`text_console(...)`](../api/text-console.md)
+- [`TextFormatterConfig`](../api/text-formatter-config.md)
+- [`text_formatter(...)`](../api/text-formatter.md)
+- [`ColorMode`](../api/color-mode.md)

docs/extend/index.md

@@ -0,0 +1,14 @@
+# Extend A Logger
+
+Start from an [Example flow](../examples/index.md), then add one extension at a time. These pages explain when an abstraction is useful and which operational boundary it introduces.
+
+## Extension Map
+
+| Need | Extension | Main trade-off |
+| --- | --- | --- |
+| Absorb short output bursts | [Queueing](./queue.md) | You must choose overflow and flush behavior. |
+| Send records to multiple destinations or route by level | [Sink composition](./composition.md) | More explicit construction than presets. |
+| Control terminal appearance | [Text formatting](./formatting.md) | Formatting affects presentation, not record structure. |
+| Share code across native and web targets | [Target boundaries](./targets.md) | File and async runtime behavior differ by backend. |
+
+For exact function signatures, follow each page's links into the [API reference](../api/index.md).

docs/extend/queue.md

@@ -0,0 +1,30 @@
+# Queueing And Overflow
+
+Use a queue when a short burst of log writes should not immediately reach the output sink. Queueing is explicit because loss behavior is an application decision.
+
+## Add A Synchronous Queue
+
+```moonbit
+let config = @log.with_queue(
+  @log.text_console(target="service"),
+  max_pending=128,
+  overflow=@log.QueueOverflowPolicy::DropOldest,
+)
+let logger = @log.build_logger(config)
+
+logger.info("queued record")
+ignore(logger.flush())
+```
+
+`DropOldest` preserves the newest operational information when the queue is full. Use `DropNewest` when preserving earlier records matters more. Calling `flush()` at a shutdown boundary makes the pending-record policy visible in application code.
+
+## When To Use Async Instead
+
+The synchronous queue is configuration around a normal runtime logger. When a native async application needs a worker lifecycle and batching, follow [Async logger lifecycle](../examples/async.md) instead.
+
+## API Reference
+
+- [`with_queue(...)`](../api/with-queue.md)
+- [`QueueConfig`](../api/queue-config.md)
+- [`QueueOverflowPolicy`](../api/queue-overflow-policy.md)
+- [`flush()`](../api/configured-logger-flush.md)

docs/extend/targets.md

@@ -0,0 +1,33 @@
+# Target Boundaries
+
+BitLogger keeps a portable structured logging surface, but native file output and async worker behavior are target-sensitive. Keep those boundaries in application code instead of assuming every sink behaves identically everywhere.
+
+## Portable Default
+
+`console(...)`, `json_console(...)`, structured fields, filters, patches, and the ordinary logger surface are the appropriate starting point for code shared across targets.
+
+## Native-Only File Output
+
+```moonbit
+if @log.native_files_supported() {
+  let logger = @log.build_logger(@log.file("service.log") catch {
+    err => {
+      ignore(err)
+      return
+    }
+  })
+  logger.info("file output enabled")
+}
+```
+
+File sinks need native filesystem support. Do not construct a file-only configuration unconditionally in code intended for web targets.
+
+## Async Library Versus Async Entry Point
+
+The async library exposes a compatibility surface across declared targets, while an executable `async fn main` still has stricter entry-point support. Keep a native-only executable example separate from portable library code.
+
+## API Reference
+
+- [`native_files_supported()`](../api/native-files-supported.md)
+- [Target verification](../api/target-verification.md)
+- [Async logger lifecycle](../examples/async.md)

docs/index.md

@@ -4,31 +4,29 @@ layout: home
 hero:
   name: BitLogger
   text: Structured logging for MoonBit
-  tagline: API reference, examples, and release notes for BitLogger.
+  tagline: Start with a runnable logging flow, then extend it with precise API reference.
   actions:
     - theme: brand
-      text: Open API Reference
-      link: /api/
+      text: Start Examples
+      link: /examples/
     - theme: alt
-      text: Read Release Notes
-      link: /changes/
+      text: Extend A Logger
+      link: /extend/
     - theme: alt
       text: Mooncake Package
       link: https://mooncakes.io/docs/Nanaloveyuki/BitLogger
 
 features:
-  - title: Structured logging
-    details: Levels, targets, message fields, and configurable text or JSON output.
-  - title: Sync and async paths
-    details: API reference covers both the main package and the async package surface.
-  - title: Config and runtime helpers
-    details: Browse builders, presets, file helpers, queue helpers, and verification notes quickly.
+  - title: Examples first
+    details: Follow complete console, file, config, and async flows before looking up individual symbols.
+  - title: Extend deliberately
+    details: Add queues, custom sink graphs, formatting, and target-specific behavior only when the base flow needs them.
+  - title: API as reference
+    details: Use the one-symbol-per-page API reference for exact signatures, contracts, and edge cases.
 ---
 
 ## Start Here
 
-<HomeDocHub />
-
-- Use [API Reference](./api/index.md) when you want the canonical one-file-per-public-API docs.
-- Use [Release Notes](./changes/index.md) when you want version-scoped changes and publish-facing summaries.
-- Use [Chinese README](https://github.com/Nanaloveyuki/BitLogger/blob/main/README.md) or [English README](./README-en.md) when you want a shorter project overview first.
+1. Read [Examples](./examples/index.md) for an end-to-end path from installation to a running logger.
+2. Read [Extend](./extend/index.md) when the base console flow needs queueing, custom routing, formatting, files, or target-aware behavior.
+3. Use [API Reference](./api/index.md) for exact contracts and [Release Notes](./changes/index.md) for version history.

docs/zh/api/async.md

@@ -0,0 +1,50 @@
+# 异步生命周期 API
+
+异步 API 从 combined config 构建 Logger，再以单 worker 生命周期处理待写入记录。可执行 `async fn main` 仍应按目标平台边界使用。
+
+## 解析与构建
+
+```moonbit
+pub fn parse_async_logger_build_config_text(
+  input : String,
+) -> AsyncLoggerBuildConfig raise
+
+pub fn build_async_logger(
+  config : AsyncLoggerBuildConfig,
+) -> AsyncLogger[RuntimeSink]
+```
+
+解析函数同时验证 `logger` 与 `async_config` 两部分；缺少任一部分时使用对应默认配置。构建函数先复用同步 `build_logger(config.logger)` 路径，再包裹异步层，因此保留同步 sink、文件与可选同步队列的运行时语义。
+
+```moonbit
+let config = @async_log.parse_async_logger_build_config_text(raw) catch {
+  err => { ignore(err); return }
+}
+let logger = @async_log.build_async_logger(config)
+```
+
+## `run()`
+
+```moonbit
+pub async fn AsyncLogger::run(self : AsyncLogger[S]) -> Unit
+```
+
+启动 drain worker。单个 Logger 只能同时拥有一个 worker；已经运行时再次调用会失败，关闭后的 Logger 也不能重新启动。worker 正常在队列关闭时退出；worker 失败时会记录状态并将错误向上传递。
+
+## `shutdown()`
+
+```moonbit
+pub async fn AsyncLogger::shutdown(
+  self : AsyncLogger[S],
+  clear? : Bool = false,
+) -> Unit
+```
+
+`clear=false` 先等待 idle 再关闭；`clear=true` 立即关闭并放弃待处理记录。两条路径都会等待活动 worker 退出。没有运行 worker 且仍有待处理记录时，`clear=false` 可能无法推进，因此应用应保证先启动 `run()`。
+
+## 英文原始 API
+
+- [`parse_async_logger_build_config_text(...)`](../../api/parse-async-logger-build-config-text.md)
+- [`build_async_logger(...)`](../../api/build-async-logger.md)
+- [`run()`](../../api/async-logger-run.md)
+- [`shutdown()`](../../api/async-logger-shutdown.md)

docs/zh/api/basics.md

@@ -0,0 +1,55 @@
+# 基础记录 API
+
+控制台示例依赖以下四个入口：先用 preset 描述输出，再由 `build_logger(...)` 构建运行时 Logger，最后用 `field(...)` 附加结构化上下文。
+
+## `console(...)` 与 `json_console(...)`
+
+```moonbit
+pub fn console(
+  min_level~ : Level = Level::Info,
+  target~ : String = "",
+  timestamp~ : Bool = false,
+) -> LoggerConfig
+
+pub fn json_console(
+  min_level~ : Level = Level::Info,
+  target~ : String = "",
+  timestamp~ : Bool = false,
+) -> LoggerConfig
+```
+
+两者都只生成 `LoggerConfig`，不会直接创建运行时 Logger。`console(...)` 适合人读输出，`json_console(...)` 适合按行采集的机器读取输出；默认都不带队列。
+
+## `field(...)`
+
+```moonbit
+pub fn field(key : String, value : String) -> Field
+```
+
+创建一个结构化字段。它保留原始 key/value，不做去重、归一化或校验；应使用稳定字段名，便于下游筛选。
+
+```moonbit
+logger.info("accepted", fields=[@log.field("user", "alice")])
+```
+
+## `build_logger(...)`
+
+```moonbit
+pub fn build_logger(config : LoggerConfig) -> ConfiguredLogger
+```
+
+这是同步 config 到运行时的桥梁：它先按 `config.sink` 构建 `RuntimeSink`，再应用可选的 `config.queue`。返回值仍保留普通日志方法，以及适用时的队列和文件控制方法。
+
+```moonbit
+let logger = @log.build_logger(
+  @log.console(min_level=@log.Level::Info, target="service"),
+)
+logger.info("ready", fields=[@log.field("port", "8080")])
+```
+
+## 英文原始 API
+
+- [`console(...)`](../../api/console.md)
+- [`json_console(...)`](../../api/json-console.md)
+- [`field(...)`](../../api/field.md)
+- [`build_logger(...)`](../../api/build-logger.md)

docs/zh/api/composition.md

@@ -0,0 +1,52 @@
+# Sink 组合 API
+
+当预设输出不足以表达路由规则时，使用 typed `Logger::new(...)` 和 sink 组合函数。它们接收完整 `Record`，因此仍保留 level、target、message 与 fields。
+
+## `Logger::new(...)`
+
+```moonbit
+pub fn Logger::new(
+  sink : S,
+  min_level~ : Level = Level::Info,
+  target~ : String = "",
+) -> Logger[S]
+```
+
+从任意 `Sink` 实现创建 typed Logger。`min_level` 在任何 sink 写入前生效；`target` 是默认值，之后可由 `with_target(...)`、`child(...)` 或单次 `log(..., target=...)` 覆盖。
+
+## `fanout_sink(...)`
+
+```moonbit
+pub fn fanout_sink(left : A, right : B) -> FanoutSink[A, B]
+```
+
+每条记录写入两个目的地，适合控制台加 JSON，或控制台加 callback。右侧获得独立记录副本，两个写入在记录值层面互不影响。
+
+## `split_by_level(...)`
+
+```moonbit
+pub fn split_by_level(
+  left : A,
+  right : B,
+  min_level~ : Level = Level::Warn,
+) -> SplitSink[A, B]
+```
+
+达到阈值的记录进入 `left`，低于阈值的记录进入 `right`。典型用法是把 warning/error 单独输出，而 info/debug 留在普通控制台。
+
+## `callback_sink(...)`
+
+```moonbit
+pub fn callback_sink(
+  callback : (Record) -> Unit,
+) -> CallbackSink
+```
+
+将完整结构化 `Record` 交给应用回调。适合测试、自定义桥接与集成；它不自动格式化记录。
+
+## 英文原始 API
+
+- [`Logger::new(...)`](../../api/logger-new.md)
+- [`fanout_sink(...)`](../../api/fanout-sink.md)
+- [`split_by_level(...)`](../../api/split-by-level.md)
+- [`callback_sink(...)`](../../api/callback-sink.md)

docs/zh/api/configuration.md

@@ -0,0 +1,53 @@
+# 配置与队列 API
+
+这一组 API 将外部 JSON 或 typed config 变成同步 Logger，并明确规定满队列和关闭时的处理方式。
+
+## `parse_logger_config_text(...)`
+
+```moonbit
+pub fn parse_logger_config_text(input : String) -> LoggerConfig raise ConfigError
+```
+
+解析并验证 JSON，但不构建运行时 Logger。缺省字段使用构造器默认值；无效 JSON、错误类型、未知枚举值或空文件路径都会抛出 `ConfigError`。
+
+```moonbit
+let config = @log.parse_logger_config_text(raw) catch {
+  err => { ignore(err); return }
+}
+let logger = @log.build_logger(config)
+```
+
+## `with_queue(...)`、`QueueConfig` 与溢出策略
+
+```moonbit
+pub fn with_queue(
+  config : LoggerConfig,
+  max_pending~ : Int = 0,
+  overflow~ : QueueOverflowPolicy = QueueOverflowPolicy::DropNewest,
+) -> LoggerConfig
+
+pub fn QueueConfig::new(
+  max_pending : Int,
+  overflow~ : QueueOverflowPolicy = QueueOverflowPolicy::DropNewest,
+) -> QueueConfig
+```
+
+`with_queue(...)` 是 preset 组合入口；`QueueConfig::new(...)` 用于手写 `LoggerConfig`。两者配置同步 `QueuedSink`，不是异步包的 worker 队列。
+
+`DropNewest` 丢弃新到记录，`DropOldest` 丢弃最早待处理记录。选择取决于业务更需要保留早期还是最新状态。
+
+## `flush()`
+
+```moonbit
+pub fn ConfiguredLogger::flush(self : ConfiguredLogger) -> Bool
+```
+
+在退出或需要确认输出边界时调用。对于队列和文件 sink，它会走对应运行时 flush 路径；返回值表示该路径是否成功。
+
+## 英文原始 API
+
+- [`parse_logger_config_text(...)`](../../api/parse-logger-config-text.md)
+- [`with_queue(...)`](../../api/with-queue.md)
+- [`QueueConfig`](../../api/queue-config.md)
+- [`QueueOverflowPolicy`](../../api/queue-overflow-policy.md)
+- [`flush()`](../../api/configured-logger-flush.md)

docs/zh/api/file-output.md

@@ -0,0 +1,49 @@
+# 文件输出 API
+
+文件输出是 native 能力。先检查能力，再创建文件配置，最后在有序退出时 flush 并关闭。
+
+## `native_files_supported()`
+
+```moonbit
+pub fn native_files_supported() -> Bool
+```
+
+native 后端当前返回 `true`，非文件能力后端返回 `false`。这是运行时能力检查，不保证后续文件操作一定成功，路径、权限和文件系统状态仍可能导致失败。
+
+## `file(...)` 与 `with_file_rotation(...)`
+
+```moonbit
+pub fn file(
+  path : String,
+  min_level~ : Level = Level::Info,
+  target~ : String = "",
+  timestamp~ : Bool = false,
+  append~ : Bool = true,
+  auto_flush~ : Bool = true,
+  rotation~ : FileRotation? = None,
+  text_formatter~ : TextFormatterConfig = default_text_formatter_config(),
+) -> LoggerConfig raise ConfigError
+
+pub fn with_file_rotation(
+  config : LoggerConfig,
+  max_bytes : Int,
+  max_backups~ : Int = 1,
+) -> LoggerConfig
+```
+
+`file(...)` 要求非空路径。`with_file_rotation(...)` 只对 file config 生效；输入不是文件 sink 时原样返回。`max_bytes` 是活动文件上限，`max_backups` 是保留的轮转备份数。
+
+## `file_close()`
+
+```moonbit
+pub fn ConfiguredLogger::file_close(self : ConfiguredLogger) -> Bool
+```
+
+关闭 config 构建的文件 sink。队列文件 sink 会依次 drain、flush、close；只有整条路径成功且期间没有新的写入、flush 或轮转失败时才返回 `true`。非文件 sink 返回 `false`。
+
+## 英文原始 API
+
+- [`native_files_supported()`](../../api/native-files-supported.md)
+- [`file(...)`](../../api/file.md)
+- [`with_file_rotation(...)`](../../api/with-file-rotation.md)
+- [`file_close()`](../../api/configured-logger-file-close.md)

docs/zh/api/formatting.md

@@ -0,0 +1,40 @@
+# 文本格式 API
+
+文本格式只改变呈现，不改变 `Record` 的结构。需要稳定机器消费时，优先使用 `json_console(...)`。
+
+## `text_console(...)`
+
+```moonbit
+pub fn text_console(
+  min_level~ : Level = Level::Info,
+  target~ : String = "",
+  timestamp~ : Bool = false,
+  text_formatter~ : TextFormatterConfig = default_text_formatter_config(),
+) -> LoggerConfig
+```
+
+生成 `SinkKind::TextConsole` 配置，并复制 formatter 配置。和其他 preset 一样，它不直接构建 Logger，也默认不带队列。
+
+## `TextFormatterConfig` 与 `text_formatter(...)`
+
+`TextFormatterConfig::new(...)` 用于 config-first 路径，控制 timestamp、level、target、fields、分隔符与 template。`text_formatter(...)` 构建直接传给 `text_console_sink(...)` 的运行时 formatter。
+
+```moonbit
+let config = @log.text_console(
+  text_formatter=@log.TextFormatterConfig::new(
+    show_timestamp=false,
+    template="[{level}] {target} {message} :: {fields}",
+  ),
+)
+```
+
+## `ColorMode`
+
+`ColorMode` 控制文本 formatter 的颜色策略。终端样式只服务可读性；业务语义仍应放在 level、target 和 fields 中。
+
+## 英文原始 API
+
+- [`text_console(...)`](../../api/text-console.md)
+- [`TextFormatterConfig`](../../api/text-formatter-config.md)
+- [`text_formatter(...)`](../../api/text-formatter.md)
+- [`ColorMode`](../../api/color-mode.md)

docs/zh/api/index.md

@@ -0,0 +1,14 @@
+# 高频 API
+
+这一层只覆盖 Examples 和 Extend 中直接使用、或应用启动时高频需要的 API。它按使用主题归纳，避免把阅读路径重新拆回一函数一页。
+
+| 场景 | 中文说明 | 英文精确参考 |
+| --- | --- | --- |
+| 第一条结构化日志 | [基础记录](./basics.md) | [完整 API 索引](../../api/index.md) |
+| 配置、队列与 flush | [配置与队列](./configuration.md) | [config 分类](../../api/index.md) |
+| native 文件输出 | [文件输出](./file-output.md) | [file/sink 分类](../../api/index.md) |
+| 终端可读性 | [文本格式](./formatting.md) | [formatter 分类](../../api/index.md) |
+| 后台异步处理 | [异步生命周期](./async.md) | [async 分类](../../api/index.md) |
+| 多目的地与按 level 路由 | [Sink 组合](./composition.md) | [sink 分类](../../api/index.md) |
+
+每个中文页面保留高频签名与行为边界；需要全部参数、错误条件或较少使用的公开符号时，沿页面内链接进入英文原始 API。

docs/zh/examples/async.md

@@ -0,0 +1,47 @@
+# 异步日志生命周期
+
+当 native 异步应用需要通过异步队列处理日志写入时，使用异步包。库声明的可用目标比可执行 `async fn main` 示例更广，仓库示例仍以 native 为主。
+
+## 导入两个包
+
+```moonbit
+import {
+  "Nanaloveyuki/BitLogger/src" @log,
+  "Nanaloveyuki/BitLogger/src-async" @async_log,
+  "moonbitlang/async",
+}
+```
+
+## 构建、运行、关闭
+
+```moonbit
+async fn main {
+  let raw = "{\"logger\":{\"min_level\":\"info\",\"target\":\"service.async\",\"sink\":{\"kind\":\"text_console\"}},\"async_config\":{\"max_pending\":64,\"overflow\":\"DropOldest\",\"max_batch\":16,\"linger_ms\":5,\"flush\":\"Batch\"}}"
+  let config = @async_log.parse_async_logger_build_config_text(raw) catch {
+    err => {
+      ignore(err)
+      return
+    }
+  }
+  let logger = @async_log.build_async_logger(config)
+
+  @async.with_task_group(group => {
+    group.spawn_bg(allow_failure=true, () => logger.run())
+    logger.info("worker started", fields=[@log.field("mode", "async")])
+    logger.shutdown()
+  })
+}
+```
+
+`run()` 持有 worker 循环。先启动它再记录日志，并调用 `shutdown()`，使待处理记录按配置的 flush 策略结束。
+
+## 运行仓库示例
+
+```bash
+moon run examples/async_basic --target native
+```
+
+## 下一步
+
+- 查看[队列](../extend/queue.md)中的溢出与 flush 选择。
+- 阅读[异步生命周期 API](../api/async.md)；完整契约仍可查询[英文 API 索引](../../api/index.md)。

docs/zh/examples/config.md

@@ -0,0 +1,35 @@
+# 配置驱动构建
+
+当 level、目标名、输出方式或队列策略应由部署配置决定时，使用这一流程。
+
+## 解析、构建、记录
+
+```moonbit
+let raw = "{\"min_level\":\"info\",\"target\":\"service\",\"sink\":{\"kind\":\"text_console\",\"text_formatter\":{\"show_timestamp\":false,\"separator\":\" | \"}},\"queue\":{\"max_pending\":64,\"overflow\":\"DropOldest\"}}"
+
+let config = @log.parse_logger_config_text(raw) catch {
+  err => {
+    ignore(err)
+    println("invalid logger configuration")
+    return
+  }
+}
+
+let logger = @log.build_logger(config)
+logger.info("configured logger ready")
+ignore(logger.flush())
+```
+
+解析先验证数据，再构造运行时 Logger。真实部署应将原始配置放在应用代码之外，并在配置进入进程的边界处理错误。
+
+## 运行仓库示例
+
+```bash
+moon run examples/config_build
+```
+
+## 下一步
+
+- 需要明确选择满队列时的行为，阅读[队列](../extend/queue.md)。
+- 需要后台 worker 生命周期时，阅读[异步日志生命周期](./async.md)。
+- 阅读[配置与队列 API](../api/configuration.md)；完整契约仍可查询[英文 API 索引](../../api/index.md)。

docs/zh/examples/console.md

@@ -0,0 +1,55 @@
+# 控制台与结构化字段
+
+命令行工具和服务都可以从这一流程开始。一条记录由 level、target、message 与可选 fields 构成。
+
+## 安装与导入
+
+```bash
+moon new log-demo
+cd log-demo
+moon add Nanaloveyuki/BitLogger@0.7.1
+```
+
+在应用的 `moon.pkg` 中加入：
+
+```moonbit
+import {
+  "Nanaloveyuki/BitLogger/src" @log,
+}
+```
+
+## 构建控制台 Logger
+
+```moonbit
+fn main {
+  let logger = @log.build_logger(
+    @log.console(min_level=@log.Level::Info, target="service.http"),
+  )
+
+  logger.info("listening", fields=[
+    @log.field("port", "8080"),
+    @log.field("environment", "development"),
+  ])
+  logger.warn("slow request", fields=[@log.field("path", "/health")])
+}
+```
+
+`min_level` 在记录到达 sink 前过滤日志；`target` 用于识别子系统；fields 用于携带可查询上下文，而不是拼接到 message 中。
+
+## 切换为 JSON
+
+保持日志调用不变，只替换配置：
+
+```moonbit
+let logger = @log.build_logger(
+  @log.json_console(min_level=@log.Level::Info, target="service.http"),
+)
+```
+
+当日志采集器按行处理结构化记录时，JSON 输出更合适。
+
+## 下一步
+
+- 需要自定义终端输出时，阅读[文本格式](../extend/formatting.md)。
+- 需要由 JSON 配置构建时，阅读[配置构建](./config.md)。
+- 阅读[基础记录 API](../api/basics.md)；完整契约仍可查询[英文 API 索引](../../api/index.md)。

docs/zh/examples/file-rotation.md

@@ -0,0 +1,51 @@
+# 文件输出与轮转
+
+文件输出面向需要本地持久化的 native 应用。跨端代码应先判断能力，并保留控制台回退方案。
+
+## 检查能力
+
+```moonbit
+if !@log.native_files_supported() {
+  println("file logging is unavailable on this target")
+  return
+}
+```
+
+## 构建可轮转文件 Logger
+
+```moonbit
+let config = @log.with_file_rotation(
+  @log.file(
+    "service.log",
+    min_level=@log.Level::Info,
+    target="service.file",
+    auto_flush=true,
+  ) catch {
+    err => {
+      ignore(err)
+      return
+    }
+  },
+  1024 * 1024,
+  max_backups=3,
+)
+
+let logger = @log.build_logger(config)
+logger.info("file logger ready")
+ignore(logger.flush())
+ignore(logger.file_close())
+```
+
+轮转阈值是活动文件的字节数，`max_backups=3` 保留备份链。应用有序退出时必须关闭文件 Logger。
+
+## 运行仓库示例
+
+```bash
+moon run examples/file_rotation --target native
+```
+
+## 下一步
+
+- 写入突发较多时，加入[队列](../extend/queue.md)。
+- 与 web 目标共享代码前，阅读[目标平台边界](../extend/targets.md)。
+- 阅读[文件输出 API](../api/file-output.md)；完整契约仍可查询[英文 API 索引](../../api/index.md)。

docs/zh/examples/index.md

@@ -0,0 +1,24 @@
+# 示例
+
+示例是 BitLogger 的主学习路径。每页从一个应用需求开始，给出完整最小代码，再链接到英文 API 参考查看精确契约。
+
+## 选择流程
+
+| 需求 | 从这里开始 | 后续扩展 |
+| --- | --- | --- |
+| 在终端输出结构化日志 | [控制台与字段](./console.md) | [文本格式](../extend/formatting.md) |
+| 保存本地日志并限制磁盘占用 | [文件轮转](./file-rotation.md) | [目标平台边界](../extend/targets.md) |
+| 由应用配置决定日志行为 | [配置构建](./config.md) | [队列](../extend/queue.md) |
+| 在 native 异步应用中处理日志写入 | [异步生命周期](./async.md) | [Sink 组合](../extend/composition.md) |
+
+## 可运行源码
+
+仓库中的 `examples/` 是可执行参考；本目录说明何时选择它们、如何运行，以及下一步应该扩展什么：
+
+- `examples/console_basic`
+- `examples/config_build`
+- `examples/file_rotation`
+- `examples/async_basic`
+- `examples/presets`、`examples/text_formatter`、`examples/style_tags`
+
+遇到函数签名、错误语义或边界条件时，请查询[英文 API 参考](../../api/index.md)。

docs/zh/extend/composition.md

@@ -0,0 +1,39 @@
+# Sink 组合
+
+Preset 覆盖常见的控制台和文件配置。只有当记录需要路由或多个输出目的地时，才直接构造 `Logger::new(...)`。
+
+## 同时发送到两个目的地
+
+```moonbit
+let logger = @log.Logger::new(
+  @log.fanout_sink(@log.console_sink(), @log.json_console_sink()),
+  min_level=@log.Level::Info,
+  target="service",
+)
+
+logger.info("request complete", fields=[@log.field("status", "200")])
+```
+
+`fanout_sink(...)` 将同一记录写入每个子 Sink，因此应用可以同时保留面向人的控制台输出和面向采集器的 JSON 输出。
+
+## 单独处理警告以上日志
+
+```moonbit
+let logger = @log.Logger::new(
+  @log.split_by_level(
+    @log.callback_sink(fn(rec) {
+      println("alert: \{rec.message}")
+    }),
+    @log.console_sink(),
+    min_level=@log.Level::Warn,
+  ),
+  min_level=@log.Level::Trace,
+  target="service",
+)
+```
+
+只有当路由规则属于应用设计时才使用直接 Sink 组合；单一输出时，preset 更容易审查和维护。
+
+## API
+
+阅读[Sink 组合 API](../api/composition.md)；完整契约仍可查询[英文 API 索引](../../api/index.md)。

docs/zh/extend/formatting.md

@@ -0,0 +1,41 @@
+# 文本格式与样式
+
+格式化只改变呈现，记录本身的 level、target、message 和 fields 不变。面向人时使用文本输出；由其他系统解析时使用 JSON。
+
+## 自定义文本形状
+
+```moonbit
+let logger = @log.build_logger(
+  @log.text_console(
+    min_level=@log.Level::Info,
+    target="service",
+    text_formatter=@log.TextFormatterConfig::new(
+      show_timestamp=false,
+      field_separator=",",
+      template="[{level}] {target} {message} :: {fields}",
+    ),
+  ),
+)
+
+logger.info("ready", fields=[@log.field("port", "8080")])
+```
+
+模板控制可见顺序。fields 应保持独立于 message，以便不同 Sink 一致渲染。
+
+## 添加命名样式
+
+```moonbit
+let formatter = @log.text_formatter(
+  show_timestamp=false,
+  color_mode=@log.ColorMode::Always,
+).with_style_tags(
+  @log.default_style_tag_registry()
+  .set_tag("accent", fg=Some("#4cc9f0"), bold=true),
+)
+```
+
+样式标签是终端呈现元数据，不应作为唯一的业务或运维语义；语义仍应保存在 level、target 与 fields 中。
+
+## API
+
+阅读[文本格式 API](../api/formatting.md)；完整契约仍可查询[英文 API 索引](../../api/index.md)。

docs/zh/extend/index.md

@@ -0,0 +1,14 @@
+# 扩展 Logger
+
+先完成一个[示例流程](../examples/index.md)，再一次只加入一种扩展能力。这些页面说明某个抽象何时有用，以及它会引入什么运行时边界。
+
+## 扩展地图
+
+| 需求 | 扩展 | 主要取舍 |
+| --- | --- | --- |
+| 吸收短时输出突发 | [队列](./queue.md) | 必须选择溢出与 flush 行为。 |
+| 同时发送到多个位置或按 level 路由 | [Sink 组合](./composition.md) | 比 preset 更需要显式构造。 |
+| 调整终端可读性 | [文本格式](./formatting.md) | 格式只改变呈现，不改变记录结构。 |
+| 在 native 与 web 目标之间共享代码 | [目标平台边界](./targets.md) | 文件与异步运行时行为因后端而异。 |
+
+需要精确函数签名时，沿页面链接进入[英文 API 参考](../../api/index.md)。

docs/zh/extend/queue.md

@@ -0,0 +1,27 @@
+# 队列与溢出策略
+
+当短时日志突发不应立即写入输出 Sink 时使用队列。队列是显式能力，因为丢弃策略必须由应用决定。
+
+## 加入同步队列
+
+```moonbit
+let config = @log.with_queue(
+  @log.text_console(target="service"),
+  max_pending=128,
+  overflow=@log.QueueOverflowPolicy::DropOldest,
+)
+let logger = @log.build_logger(config)
+
+logger.info("queued record")
+ignore(logger.flush())
+```
+
+`DropOldest` 在队列已满时保留最新运行信息。若更重视先到的记录，可选择 `DropNewest`。在退出边界调用 `flush()`，让待处理记录策略在应用代码中清晰可见。
+
+## 何时改用异步 Logger
+
+同步队列只是普通运行时 Logger 的一层配置。当 native 异步应用需要 worker 生命周期和批处理时，转到[异步日志生命周期](../examples/async.md)。
+
+## API
+
+阅读[配置与队列 API](../api/configuration.md)；完整契约仍可查询[英文 API 索引](../../api/index.md)。

docs/zh/extend/targets.md

@@ -0,0 +1,31 @@
+# 目标平台边界
+
+BitLogger 保持可移植的结构化日志表面，但 native 文件输出与异步 worker 行为依赖目标平台。应把这些边界写在应用代码中，而不是假设每种 Sink 在所有后端都相同。
+
+## 可移植默认值
+
+`console(...)`、`json_console(...)`、结构化 fields、filter、patch 与普通 Logger 表面适合作为跨端共享代码的起点。
+
+## 仅 native 的文件输出
+
+```moonbit
+if @log.native_files_supported() {
+  let logger = @log.build_logger(@log.file("service.log") catch {
+    err => {
+      ignore(err)
+      return
+    }
+  })
+  logger.info("file output enabled")
+}
+```
+
+文件 Sink 需要 native 文件系统支持。面向 web 目标的代码不应无条件构造只包含文件输出的配置。
+
+## 异步库与异步入口
+
+异步库在声明目标上提供兼容表面，但可执行 `async fn main` 的入口支持更严格。请把 native-only 可执行示例与可移植库代码分开。
+
+## API
+
+阅读[文件输出 API](../api/file-output.md)和[异步生命周期](../examples/async.md)。完整目标验证记录仍在[英文 API](../../api/target-verification.md)。

docs/zh/index.md

@@ -0,0 +1,32 @@
+---
+layout: home
+
+hero:
+  name: BitLogger
+  text: MoonBit 结构化日志库
+  tagline: 先完成一条可运行的日志流程，再按需扩展并查询 API。
+  actions:
+    - theme: brand
+      text: 从示例开始
+      link: /zh/examples/
+    - theme: alt
+      text: 扩展 Logger
+      link: /zh/extend/
+    - theme: alt
+      text: API 参考（英文）
+      link: /api/
+
+features:
+  - title: 示例优先
+    details: 从控制台、文件、配置和异步四条完整流程开始，而不是从 API 文件名开始。
+  - title: 按需扩展
+    details: 只在基础流程需要时再加入队列、组合 Sink、格式化和跨端处理。
+  - title: API 作为参考
+    details: 英文 API 页面保留精确签名、契约与边界说明。
+---
+
+## 从这里开始
+
+1. 阅读[示例](./examples/index.md)，完成从安装到运行 Logger 的全流程。
+2. 当基础控制台流程需要更多能力时，阅读[扩展](./extend/index.md)。
+3. 需要高频签名和边界时，查询[中文高频 API](./api/index.md)；较少使用的符号仍进入[英文完整 API 参考](../api/index.md)。

examples/async_basic/moon.pkg

@@ -6,6 +6,4 @@ import {
 
 supported_targets = "+native"
 
-options(
-  is_main: true,
-)
+pkgtype(kind: "executable")

examples/basic/moon.pkg

@@ -2,6 +2,4 @@ import {
   "Nanaloveyuki/BitLogger/src" @lib,
 }
 
-options(
-  "is-main": true,
-)
+pkgtype(kind: "executable")

examples/config_build/moon.pkg

@@ -2,6 +2,4 @@ import {
   "Nanaloveyuki/BitLogger/src" @lib,
 }
 
-options(
-  "is-main": true,
-)
+pkgtype(kind: "executable")

examples/console_basic/moon.pkg

@@ -2,6 +2,4 @@ import {
   "Nanaloveyuki/BitLogger/src" @lib,
 }
 
-options(
-  "is-main": true,
-)
+pkgtype(kind: "executable")

examples/file_rotation/moon.pkg

@@ -2,6 +2,4 @@ import {
   "Nanaloveyuki/BitLogger/src" @lib,
 }
 
-options(
-  "is-main": true,
-)
+pkgtype(kind: "executable")

examples/presets/moon.pkg

@@ -2,6 +2,4 @@ import {
   "Nanaloveyuki/BitLogger/src" @lib,
 }
 
-options(
-  "is-main": true,
-)
+pkgtype(kind: "executable")

examples/style_tags/moon.pkg

@@ -2,6 +2,4 @@ import {
   "Nanaloveyuki/BitLogger/src" @lib,
 }
 
-options(
-  "is-main": true,
-)
+pkgtype(kind: "executable")

examples/text_formatter/moon.pkg

@@ -2,6 +2,4 @@ import {
   "Nanaloveyuki/BitLogger/src" @lib,
 }
 
-options(
-  "is-main": true,
-)
+pkgtype(kind: "executable")

logs/.gitkeep

@@ -0,0 +1 @@
+

moon.mod

@@ -1,10 +1,10 @@
 name = "Nanaloveyuki/BitLogger"
 
-version = "0.7.0"
+version = "0.7.1"
 
 import {
   "maria/json_parser@0.1.1",
-  "moonbitlang/async@0.20.0",
+  "moonbitlang/async@0.20.2",
 }
 
 readme = "src/README.mbt.md"

src-async/BitLoggerAsync_test.mbt

@@ -2404,7 +2404,7 @@ async test "library async parse-build unwrap matches parsed direct async builder
 
 ///|
 async test "library async parse-build unwrap preserves file-backed runtime helpers" {
-  let raw = "{\"logger\":{\"min_level\":\"warn\",\"target\":\"async.lib.json.file.same-build\",\"queue\":{\"max_pending\":3,\"overflow\":\"DropOldest\"},\"sink\":{\"kind\":\"file\",\"path\":\"async-lib-json-file-same-build.log\"}},\"async_config\":{\"max_pending\":2,\"overflow\":\"DropOldest\",\"max_batch\":1,\"linger_ms\":0,\"flush\":\"Shutdown\"}}"
+  let raw = "{\"logger\":{\"min_level\":\"warn\",\"target\":\"async.lib.json.file.same-build\",\"queue\":{\"max_pending\":3,\"overflow\":\"DropOldest\"},\"sink\":{\"kind\":\"file\",\"path\":\"logs/async-lib-json-file-same-build.log\"}},\"async_config\":{\"max_pending\":2,\"overflow\":\"DropOldest\",\"max_batch\":1,\"linger_ms\":0,\"flush\":\"Shutdown\"}}"
   let logger = parse_and_build_library_async_logger(raw)
   let full = logger.to_async_logger()
   let direct = build_async_logger(parse_async_logger_build_config_text(raw))
@@ -2920,7 +2920,7 @@ test "library async text logger ignores sink kind and still uses text formatter"
         target="async.lib.text.kind",
         sink=@bitlogger.SinkConfig::new(
           kind=@bitlogger.SinkKind::File,
-          path="ignored.log",
+          path="logs/ignored.log",
           text_formatter=@bitlogger.TextFormatterConfig::new(
             show_timestamp=false,
             separator=" | ",
@@ -3233,7 +3233,7 @@ async test "async logger projection preserves file-backed runtime helpers throug
         target="async.projected.file",
         sink=@bitlogger.SinkConfig::new(
           kind=@bitlogger.SinkKind::File,
-          path="async-projected-file.log",
+          path="logs/async-projected-file.log",
         ),
         queue=Some(
           @bitlogger.QueueConfig::new(
@@ -3530,7 +3530,7 @@ async test "application async builder preserves file-backed runtime helpers" {
       target="async.app.file.same-build",
       sink=@bitlogger.SinkConfig::new(
         kind=@bitlogger.SinkKind::File,
-        path="async-app-file-same-build.log",
+        path="logs/async-app-file-same-build.log",
       ),
       queue=Some(
         @bitlogger.QueueConfig::new(
@@ -4384,7 +4384,7 @@ test "application text async logger ignores sink kind and still uses text format
         target="async.app.text.kind.alias",
         sink=@bitlogger.SinkConfig::new(
           kind=@bitlogger.SinkKind::File,
-          path="ignored.log",
+          path="logs/ignored.log",
           text_formatter=@bitlogger.TextFormatterConfig::new(
             show_timestamp=false,
             separator=" | ",
@@ -4462,7 +4462,7 @@ test "build async text logger ignores sink kind and still uses text formatter" {
         target="async.text.kind",
         sink=@bitlogger.SinkConfig::new(
           kind=@bitlogger.SinkKind::File,
-          path="ignored.log",
+          path="logs/ignored.log",
           text_formatter=@bitlogger.TextFormatterConfig::new(
             show_timestamp=false,
             separator=" | ",
@@ -4959,7 +4959,7 @@ async test "application async parse-build matches parsed direct async builder be
 
 ///|
 async test "application async parse-build preserves file-backed runtime helpers" {
-  let raw = "{\"logger\":{\"min_level\":\"warn\",\"target\":\"async.app.json.file.same-build\",\"queue\":{\"max_pending\":3,\"overflow\":\"DropOldest\"},\"sink\":{\"kind\":\"file\",\"path\":\"async-app-json-file-same-build.log\"}},\"async_config\":{\"max_pending\":2,\"overflow\":\"DropOldest\",\"max_batch\":1,\"linger_ms\":0,\"flush\":\"Shutdown\"}}"
+  let raw = "{\"logger\":{\"min_level\":\"warn\",\"target\":\"async.app.json.file.same-build\",\"queue\":{\"max_pending\":3,\"overflow\":\"DropOldest\"},\"sink\":{\"kind\":\"file\",\"path\":\"logs/async-app-json-file-same-build.log\"}},\"async_config\":{\"max_pending\":2,\"overflow\":\"DropOldest\",\"max_batch\":1,\"linger_ms\":0,\"flush\":\"Shutdown\"}}"
   let application = parse_and_build_application_async_logger(raw)
   let direct = build_async_logger(parse_async_logger_build_config_text(raw))
 

src/BitLogger_wbtest.mbt

@@ -1,6 +1,6 @@
 ///|
 test "file sink tracks rotation failures on unavailable backend" {
-  let path = "bitlogger-rotate.log"
+  let path = "logs/bitlogger-rotate.log"
   ignore(@utils.remove_file_internal(path))
   ignore(@utils.remove_file_internal(path + ".1"))
   let sink = file_sink(path, rotation=Some(file_rotation(1, max_backups=1)))
@@ -19,7 +19,7 @@ test "file sink tracks rotation failures on unavailable backend" {
 
 ///|
 test "file sink reopen and failure counters reflect backend state" {
-  let sink = file_sink("bitlogger-reopen.log")
+  let sink = file_sink("logs/bitlogger-reopen.log")
   if sink.is_available() {
     inspect(sink.append_mode(), content="true")
     inspect(sink.open_failures(), content="0")
@@ -45,7 +45,7 @@ test "file sink reopen and failure counters reflect backend state" {
     inspect(sink.flush_failures(), content="0")
     inspect(sink.rotation_failures(), content="0")
     inspect(sink.close(), content="true")
-    ignore(@utils.remove_file_internal("bitlogger-reopen.log"))
+    ignore(@utils.remove_file_internal("logs/bitlogger-reopen.log"))
   } else {
     inspect(sink.append_mode(), content="true")
     inspect(sink.open_failures(), content="1")
@@ -71,7 +71,7 @@ test "file sink reopen and failure counters reflect backend state" {
 
 ///|
 test "file sink can rotate on native backend" {
-  let path = "bitlogger-rotate-native.log"
+  let path = "logs/bitlogger-rotate-native.log"
   ignore(@utils.remove_file_internal(path))
   ignore(@utils.remove_file_internal(path + ".1"))
   ignore(@utils.remove_file_internal(path + ".2"))
@@ -105,57 +105,3 @@ test "file sink can rotate on native backend" {
     inspect(sink.rotation_failures(), content="0")
   }
 }
-
-///|
-#cfg(platform="windows")
-test "file sink rotation failure counts partial backup-chain failure on native backend" {
-  let path = "bitlogger-rotate-partial-failure.log"
-  ignore(@utils.remove_file_internal(path))
-  ignore(@utils.remove_file_internal(path + ".1"))
-  ignore(@utils.remove_file_internal(path + ".2"))
-
-  let seed = file_sink(
-    path,
-    auto_flush=true,
-    rotation=Some(file_rotation(20, max_backups=2)),
-    formatter=fn(rec) { rec.message },
-  )
-  if seed.is_available() {
-    seed.write(record(Level::Info, "1234567890"))
-    seed.write(record(Level::Info, "abcdefghij"))
-    inspect(seed.rotation_failures(), content="0")
-    inspect(seed.close(), content="true")
-
-    let locked = @utils.open_file_handle_internal(path + ".2", true)
-    inspect(locked is Some(_), content="true")
-
-    let sink = file_sink(
-      path,
-      auto_flush=true,
-      rotation=Some(file_rotation(20, max_backups=2)),
-      formatter=fn(rec) { rec.message },
-    )
-    inspect(sink.is_available(), content="true")
-    sink.write(record(Level::Info, "klmnopqrst"))
-
-    inspect(sink.rotation_failures(), content="1")
-    inspect(sink.state().rotation_failures, content="1")
-    inspect(sink.write_failures(), content="1")
-    inspect(sink.is_available(), content="false")
-
-    match locked {
-      None => ()
-      Some(handle) => ignore(@utils.close_file_handle_internal(handle))
-    }
-
-    inspect(sink.reopen_append(), content="true")
-    inspect(sink.is_available(), content="true")
-    inspect(sink.close(), content="true")
-
-    ignore(@utils.remove_file_internal(path))
-    ignore(@utils.remove_file_internal(path + ".1"))
-    ignore(@utils.remove_file_internal(path + ".2"))
-  } else {
-    inspect(native_files_supported(), content="false")
-  }
-}

src/application_logger_facade_test.mbt

@@ -81,7 +81,7 @@ test "application logger keeps configured runtime helper surface" {
     LoggerConfig::new(
       min_level=Level::Warn,
       target="app.alias.helpers",
-      sink=SinkConfig::new(kind=SinkKind::File, path="app-alias.log"),
+      sink=SinkConfig::new(kind=SinkKind::File, path="logs/app-alias.log"),
       queue=Some(QueueConfig::new(2, overflow=QueueOverflowPolicy::DropOldest)),
     ),
   )
@@ -229,7 +229,10 @@ test "application logger file helpers match direct configured builder behavior"
   let config = LoggerConfig::new(
     min_level=Level::Warn,
     target="app.file.same-build",
-    sink=SinkConfig::new(kind=SinkKind::File, path="app-file-same-build.log"),
+    sink=SinkConfig::new(
+      kind=SinkKind::File,
+      path="logs/app-file-same-build.log",
+    ),
     queue=Some(QueueConfig::new(2, overflow=QueueOverflowPolicy::DropOldest)),
   )
   let application = build_application_logger(config)
@@ -344,7 +347,7 @@ test "application logger file controls match direct configured builder behavior"
     target="app.file.controls.same-build",
     sink=SinkConfig::new(
       kind=SinkKind::File,
-      path="app-file-controls-same-build.log",
+      path="logs/app-file-controls-same-build.log",
     ),
   )
   let application = build_application_logger(config)

src/config_model/config.mbt

@@ -42,7 +42,7 @@ pub fn TextFormatterConfig::new(
   style_markup? : @formatting.StyleMarkupMode = @formatting.StyleMarkupMode::Full,
   target_style_markup? : @formatting.StyleMarkupMode = @formatting.StyleMarkupMode::Disabled,
   fields_style_markup? : @formatting.StyleMarkupMode = @formatting.StyleMarkupMode::Disabled,
-  style_tags? : Map[String, @formatting.TextStyle] = {},
+  style_tags? : Map[String, @formatting.TextStyle] = Map([]),
 ) -> TextFormatterConfig {
   {
     show_timestamp,
@@ -380,7 +380,7 @@ fn parse_text_formatter_config(
       get_string(obj, "fields_style_markup", default="disabled"),
     ),
     style_tags=match obj.get("style_tags") {
-      None => {}
+      None => Map([])
       Some(inner) => parse_style_tags_config(inner)
     },
   )
@@ -407,7 +407,7 @@ fn parse_style_tags_config(
   value : @json_parser.JsonValue,
 ) -> Map[String, @formatting.TextStyle] raise ConfigError {
   let obj = expect_object(value, "text_formatter.style_tags")
-  let style_tags : Map[String, @formatting.TextStyle] = {}
+  let style_tags : Map[String, @formatting.TextStyle] = Map([])
   for name, item in obj {
     style_tags[name] = parse_text_style_config(
       item,
@@ -584,7 +584,7 @@ fn text_style_config_to_json(
 fn style_tags_config_to_json(
   style_tags : Map[String, @formatting.TextStyle],
 ) -> @json_parser.JsonValue {
-  let obj : Map[String, @json_parser.JsonValue] = {}
+  let obj : Map[String, @json_parser.JsonValue] = Map([])
   for name, style in style_tags {
     obj[name] = text_style_config_to_json(style)
   }

src/configured_file_controls_parity_test.mbt

@@ -5,7 +5,7 @@ test "configured logger file setters stay aligned with runtime sink setters" {
       target="config.file.setters.delegate",
       sink=SinkConfig::new(
         kind=SinkKind::File,
-        path="config-file-setters-delegate.log",
+        path="logs/config-file-setters-delegate.log",
       ),
     ),
   )
@@ -100,7 +100,7 @@ test "configured logger file reopen helpers stay aligned with runtime sink helpe
     LoggerConfig::new(
       sink=SinkConfig::new(
         kind=SinkKind::File,
-        path="config-reopen-delegate.log",
+        path="logs/config-reopen-delegate.log",
       ),
     ),
   )
@@ -174,7 +174,7 @@ test "configured logger file reset helpers stay aligned with runtime sink helper
     LoggerConfig::new(
       sink=SinkConfig::new(
         kind=SinkKind::File,
-        path="config-reset-delegate.log",
+        path="logs/config-reset-delegate.log",
         append=false,
         auto_flush=false,
         rotation=Some(file_rotation(40, max_backups=2)),

src/configured_file_controls_test.mbt

@@ -2,7 +2,7 @@
 test "configured logger file setters update file sink policy state" {
   let logger = build_logger(
     LoggerConfig::new(
-      sink=SinkConfig::new(kind=SinkKind::File, path="config-setters.log"),
+      sink=SinkConfig::new(kind=SinkKind::File, path="logs/config-setters.log"),
       queue=Some(QueueConfig::new(2, overflow=QueueOverflowPolicy::DropNewest)),
     ),
   )
@@ -61,7 +61,7 @@ test "configured logger reset policy restores configured file defaults" {
     LoggerConfig::new(
       sink=SinkConfig::new(
         kind=SinkKind::File,
-        path="config-reset-policy.log",
+        path="logs/config-reset-policy.log",
         append=false,
         auto_flush=false,
         rotation=Some(file_rotation(36, max_backups=2)),
@@ -93,7 +93,10 @@ test "configured logger reset policy restores configured file defaults" {
 test "configured logger set policy applies bundled runtime file policy" {
   let logger = build_logger(
     LoggerConfig::new(
-      sink=SinkConfig::new(kind=SinkKind::File, path="config-set-policy.log"),
+      sink=SinkConfig::new(
+        kind=SinkKind::File,
+        path="logs/config-set-policy.log",
+      ),
     ),
   )
   let default_policy = logger.file_default_policy()
@@ -140,7 +143,7 @@ test "configured non-file logger cannot reset file policy" {
 test "configured logger can reopen built file sink" {
   let logger = build_logger(
     LoggerConfig::new(
-      sink=SinkConfig::new(kind=SinkKind::File, path="config-reopen.log"),
+      sink=SinkConfig::new(kind=SinkKind::File, path="logs/config-reopen.log"),
     ),
   )
   if logger.file_available() {
@@ -199,7 +202,7 @@ test "configured non-file logger cannot reset file failure counters" {
 test "configured logger exposes file flush and close helpers" {
   let logger = build_logger(
     LoggerConfig::new(
-      sink=SinkConfig::new(kind=SinkKind::File, path="config-control.log"),
+      sink=SinkConfig::new(kind=SinkKind::File, path="logs/config-control.log"),
     ),
   )
   if logger.file_available() {
@@ -218,7 +221,10 @@ test "configured logger exposes file flush and close helpers" {
 test "configured queued file logger flushes queue through file helper" {
   let logger = build_logger(
     LoggerConfig::new(
-      sink=SinkConfig::new(kind=SinkKind::File, path="config-queued-file.log"),
+      sink=SinkConfig::new(
+        kind=SinkKind::File,
+        path="logs/config-queued-file.log",
+      ),
       queue=Some(QueueConfig::new(4, overflow=QueueOverflowPolicy::DropNewest)),
     ),
   )
@@ -257,7 +263,10 @@ test "configured queued file logger flushes queue through file helper" {
 test "configured queued file logger blocks policy mutation while queue is pending" {
   let logger = build_logger(
     LoggerConfig::new(
-      sink=SinkConfig::new(kind=SinkKind::File, path="config-queued-policy.log"),
+      sink=SinkConfig::new(
+        kind=SinkKind::File,
+        path="logs/config-queued-policy.log",
+      ),
       queue=Some(QueueConfig::new(4, overflow=QueueOverflowPolicy::DropNewest)),
     ),
   )
@@ -293,7 +302,10 @@ test "configured queued file logger blocks policy mutation while queue is pendin
 test "configured queued file logger close drains queue before teardown" {
   let logger = build_logger(
     LoggerConfig::new(
-      sink=SinkConfig::new(kind=SinkKind::File, path="config-close-queued.log"),
+      sink=SinkConfig::new(
+        kind=SinkKind::File,
+        path="logs/config-close-queued.log",
+      ),
       queue=Some(QueueConfig::new(4, overflow=QueueOverflowPolicy::DropNewest)),
     ),
   )

src/configured_file_observability_parity_test.mbt

@@ -3,7 +3,10 @@ test "configured logger file observation helpers stay aligned with runtime sink
   let file_logger = build_logger(
     LoggerConfig::new(
       target="config.file.delegate",
-      sink=SinkConfig::new(kind=SinkKind::File, path="config-file-delegate.log"),
+      sink=SinkConfig::new(
+        kind=SinkKind::File,
+        path="logs/config-file-delegate.log",
+      ),
     ),
   )
   let file_sink = file_logger.sink
@@ -74,7 +77,7 @@ test "configured logger file policy helpers stay aligned with runtime sink helpe
       target="config.file.policy.delegate",
       sink=SinkConfig::new(
         kind=SinkKind::File,
-        path="config-file-policy-delegate.log",
+        path="logs/config-file-policy-delegate.log",
         append=false,
         auto_flush=true,
         rotation=Some(file_rotation(64, max_backups=2)),
@@ -213,7 +216,7 @@ test "configured logger file flush and close stay aligned with runtime sink help
   let file_config = LoggerConfig::new(
     sink=SinkConfig::new(
       kind=SinkKind::File,
-      path="config-file-helper-delegate.log",
+      path="logs/config-file-helper-delegate.log",
     ),
   )
   let file_logger = build_logger(file_config)
@@ -245,7 +248,7 @@ test "configured logger file state helpers stay aligned with runtime sink helper
       target="config.file.state.delegate",
       sink=SinkConfig::new(
         kind=SinkKind::File,
-        path="config-file-state-delegate.log",
+        path="logs/config-file-state-delegate.log",
       ),
     ),
   )
@@ -297,7 +300,7 @@ test "configured logger file state helpers stay aligned with runtime sink helper
       target="config.file.runtime.delegate",
       sink=SinkConfig::new(
         kind=SinkKind::File,
-        path="config-file-runtime-delegate.log",
+        path="logs/config-file-runtime-delegate.log",
       ),
       queue=Some(QueueConfig::new(4, overflow=QueueOverflowPolicy::DropNewest)),
     ),

src/configured_file_observability_test.mbt

@@ -4,7 +4,7 @@ test "configured logger exposes file sink observability helpers" {
     LoggerConfig::new(
       sink=SinkConfig::new(
         kind=SinkKind::File,
-        path="config-file.log",
+        path="logs/config-file.log",
         auto_flush=false,
         rotation=Some(file_rotation(64, max_backups=3)),
       ),
@@ -13,8 +13,8 @@ test "configured logger exposes file sink observability helpers" {
   let state = logger.file_state()
   let runtime_state = logger.file_runtime_state()
   inspect(logger.file_available() == native_files_supported(), content="true")
-  inspect(logger.file_path(), content="config-file.log")
-  inspect(state.path, content="config-file.log")
+  inspect(logger.file_path(), content="logs/config-file.log")
+  inspect(state.path, content="logs/config-file.log")
   inspect(state.available == logger.file_available(), content="true")
   inspect(state.append == logger.file_append_mode(), content="true")
   inspect(state.auto_flush == logger.file_auto_flush(), content="true")
@@ -25,7 +25,7 @@ test "configured logger exposes file sink observability helpers" {
       inspect(snapshot.queued, content="false")
       inspect(snapshot.pending_count, content="0")
       inspect(snapshot.dropped_count, content="0")
-      inspect(snapshot.file.path, content="config-file.log")
+      inspect(snapshot.file.path, content="logs/config-file.log")
     }
     None => inspect(false, content="true")
   }
@@ -51,7 +51,10 @@ test "configured logger exposes file sink observability helpers" {
 test "configured logger reports disabled rotation when file sink has none" {
   let logger = build_logger(
     LoggerConfig::new(
-      sink=SinkConfig::new(kind=SinkKind::File, path="config-no-rotation.log"),
+      sink=SinkConfig::new(
+        kind=SinkKind::File,
+        path="logs/config-no-rotation.log",
+      ),
     ),
   )
   inspect(logger.file_rotation_enabled(), content="false")
@@ -79,12 +82,15 @@ test "configured non-file logger has no file runtime state" {
 test "configured file logger mirrors backend file capability" {
   let logger = build_logger(
     LoggerConfig::new(
-      sink=SinkConfig::new(kind=SinkKind::File, path="config-capability.log"),
+      sink=SinkConfig::new(
+        kind=SinkKind::File,
+        path="logs/config-capability.log",
+      ),
     ),
   )
   inspect(logger.file_available() == native_files_supported(), content="true")
   match logger.file_path_or_none() {
-    Some(path) => inspect(path, content="config-capability.log")
+    Some(path) => inspect(path, content="logs/config-capability.log")
     None => inspect(false, content="true")
   }
   inspect(logger.file_policy_or_none() is None, content="false")

src/configured_logger_facade_test.mbt

@@ -82,7 +82,10 @@ test "configured logger projection preserves file runtime helpers through unwrap
     LoggerConfig::new(
       min_level=Level::Warn,
       target="lib.projected.file",
-      sink=SinkConfig::new(kind=SinkKind::File, path="lib-projected-file.log"),
+      sink=SinkConfig::new(
+        kind=SinkKind::File,
+        path="logs/lib-projected-file.log",
+      ),
       queue=Some(QueueConfig::new(2, overflow=QueueOverflowPolicy::DropOldest)),
     ),
   )

src/file_runtime/file_sink.mbt

@@ -16,6 +16,24 @@ type Record = @core.Record
 ///|
 type RecordFormatter = @formatting.RecordFormatter
 
+///|
+priv struct RotationFileOps {
+  file_exists : (String) -> Bool
+  remove_file : (String) -> Bool
+  rename_file : (String, String) -> Bool
+}
+
+///|
+fn default_rotation_file_ops() -> RotationFileOps {
+  {
+    file_exists: fn(path) { @utils.file_exists_internal(path) },
+    remove_file: fn(path) { @utils.remove_file_internal(path) },
+    rename_file: fn(from_path, to_path) {
+      @utils.rename_file_internal(from_path, to_path)
+    },
+  }
+}
+
 ///|
 pub struct FileSink {
   priv path : String
@@ -31,6 +49,7 @@ pub struct FileSink {
   priv write_failures : Ref[Int]
   priv flush_failures : Ref[Int]
   priv rotation_failures : Ref[Int]
+  priv rotation_file_ops : Ref[RotationFileOps]
 }
 
 ///|
@@ -61,6 +80,7 @@ pub fn file_sink(
     write_failures: Ref(0),
     flush_failures: Ref(0),
     rotation_failures: Ref(0),
+    rotation_file_ops: Ref(default_rotation_file_ops()),
   }
 }
 
@@ -291,6 +311,28 @@ fn rotated_file_path(path : String, index : Int) -> String {
   "\{path}.\{index}"
 }
 
+///|
+fn remove_file_if_present(ops : RotationFileOps, path : String) -> Bool {
+  if !(ops.file_exists)(path) {
+    true
+  } else {
+    (ops.remove_file)(path) || !(ops.file_exists)(path)
+  }
+}
+
+///|
+fn rename_file_if_present(
+  ops : RotationFileOps,
+  from_path : String,
+  to_path : String,
+) -> Bool {
+  if !(ops.file_exists)(from_path) {
+    true
+  } else {
+    (ops.rename_file)(from_path, to_path) || !(ops.file_exists)(from_path)
+  }
+}
+
 ///|
 fn rotate_file_sink_internal(sink : FileSink, rotation : FileRotation) -> Bool {
   let closed = match sink.handle.val {
@@ -304,23 +346,27 @@ fn rotate_file_sink_internal(sink : FileSink, rotation : FileRotation) -> Bool {
   if !closed {
     return false
   }
+  let ops = sink.rotation_file_ops.val
   if rotation.max_backups > 0 {
-    ignore(
-      @utils.remove_file_internal(
+    if !remove_file_if_present(
+        ops,
         rotated_file_path(sink.path, rotation.max_backups),
-      ),
-    )
+      ) {
+      return false
+    }
     for index = rotation.max_backups - 1; index >= 1; {
       let from_path = rotated_file_path(sink.path, index)
       let to_path = rotated_file_path(sink.path, index + 1)
-      ignore(@utils.rename_file_internal(from_path, to_path))
+      if !rename_file_if_present(ops, from_path, to_path) {
+        return false
+      }
       continue index - 1
     }
-    ignore(
-      @utils.rename_file_internal(sink.path, rotated_file_path(sink.path, 1)),
-    )
-  } else {
-    ignore(@utils.remove_file_internal(sink.path))
+    if !rename_file_if_present(ops, sink.path, rotated_file_path(sink.path, 1)) {
+      return false
+    }
+  } else if !remove_file_if_present(ops, sink.path) {
+    return false
   }
   sink.handle.val = @utils.open_file_handle_internal(sink.path, false)
   sink.handle.val is Some(_)

src/file_runtime/file_sink_rotation_wbtest.mbt

@@ -0,0 +1,111 @@
+///|
+test "file sink counts an injected partial backup-chain failure" {
+  let test_path = "logs/file-runtime-rotate-partial-failure.log"
+  ignore(@utils.remove_file_internal(test_path))
+  ignore(@utils.remove_file_internal(test_path + ".1"))
+  ignore(@utils.remove_file_internal(test_path + ".2"))
+
+  let rotation = @file_model.file_rotation(20, max_backups=2)
+  let seed = file_sink(test_path, auto_flush=true, rotation=Some(rotation), formatter=fn(
+    rec,
+  ) {
+    rec.message
+  })
+  if seed.is_available() {
+    seed.write(@core.Record::new(@core.Level::Info, "1234567890"))
+    seed.write(@core.Record::new(@core.Level::Info, "abcdefghij"))
+    inspect(seed.rotation_failures(), content="0")
+    inspect(seed.close(), content="true")
+
+    let sink = file_sink(test_path, auto_flush=true, rotation=Some(rotation), formatter=fn(
+      rec,
+    ) {
+      rec.message
+    })
+    sink.rotation_file_ops.val = {
+      file_exists: fn(candidate) { @utils.file_exists_internal(candidate) },
+      remove_file: fn(candidate) { @utils.remove_file_internal(candidate) },
+      rename_file: fn(from_path, to_path) {
+        if from_path == test_path + ".1" && to_path == test_path + ".2" {
+          false
+        } else {
+          @utils.rename_file_internal(from_path, to_path)
+        }
+      },
+    }
+    sink.write(@core.Record::new(@core.Level::Info, "klmnopqrst"))
+
+    inspect(sink.rotation_failures(), content="1")
+    inspect(sink.state().rotation_failures, content="1")
+    inspect(sink.write_failures(), content="1")
+    inspect(sink.is_available(), content="false")
+    inspect(sink.reopen_append(), content="true")
+    inspect(sink.is_available(), content="true")
+    inspect(sink.close(), content="true")
+
+    ignore(@utils.remove_file_internal(test_path))
+    ignore(@utils.remove_file_internal(test_path + ".1"))
+    ignore(@utils.remove_file_internal(test_path + ".2"))
+  } else {
+    inspect(native_files_supported(), content="false")
+  }
+}
+
+///|
+test "file sink counts an injected oldest-backup removal failure" {
+  let test_path = "logs/file-runtime-rotate-removal-failure.log"
+  ignore(@utils.remove_file_internal(test_path))
+  ignore(@utils.remove_file_internal(test_path + ".1"))
+  ignore(@utils.remove_file_internal(test_path + ".2"))
+
+  let rotation = @file_model.file_rotation(20, max_backups=2)
+  let seed = file_sink(test_path, auto_flush=true, rotation=Some(rotation), formatter=fn(
+    rec,
+  ) {
+    rec.message
+  })
+  if seed.is_available() {
+    seed.write(@core.Record::new(@core.Level::Info, "1234567890"))
+    seed.write(@core.Record::new(@core.Level::Info, "abcdefghij"))
+    inspect(seed.close(), content="true")
+
+    let oldest = @utils.open_file_handle_internal(test_path + ".2", true)
+    inspect(oldest is Some(_), content="true")
+    match oldest {
+      None => ()
+      Some(handle) =>
+        inspect(@utils.close_file_handle_internal(handle), content="true")
+    }
+
+    let sink = file_sink(test_path, auto_flush=true, rotation=Some(rotation), formatter=fn(
+      rec,
+    ) {
+      rec.message
+    })
+    sink.rotation_file_ops.val = {
+      file_exists: fn(candidate) { @utils.file_exists_internal(candidate) },
+      remove_file: fn(candidate) {
+        if candidate == test_path + ".2" {
+          false
+        } else {
+          @utils.remove_file_internal(candidate)
+        }
+      },
+      rename_file: fn(from_path, to_path) {
+        @utils.rename_file_internal(from_path, to_path)
+      },
+    }
+    sink.write(@core.Record::new(@core.Level::Info, "klmnopqrst"))
+
+    inspect(sink.rotation_failures(), content="1")
+    inspect(sink.write_failures(), content="1")
+    inspect(sink.is_available(), content="false")
+    inspect(sink.close(), content="false")
+
+    ignore(@utils.remove_file_internal(test_path))
+    ignore(@utils.remove_file_internal(test_path + ".1"))
+    ignore(@utils.remove_file_internal(test_path + ".2"))
+  } else {
+    inspect(native_files_supported(), content="false")
+  }
+}

src/file_sink_test.mbt

@@ -8,11 +8,11 @@ test "native file support flag is queryable" {
 
 ///|
 test "file sink availability reflects backend support" {
-  let sink = file_sink("bitlogger-test.log")
+  let sink = file_sink("logs/bitlogger-test.log")
   let state = sink.state()
-  inspect(sink.path(), content="bitlogger-test.log")
+  inspect(sink.path(), content="logs/bitlogger-test.log")
   inspect(sink.is_available() == native_files_supported(), content="true")
-  inspect(state.path, content="bitlogger-test.log")
+  inspect(state.path, content="logs/bitlogger-test.log")
   inspect(state.available == sink.is_available(), content="true")
   inspect(state.append == sink.append_mode(), content="true")
   inspect(state.auto_flush == sink.auto_flush_enabled(), content="true")
@@ -42,7 +42,7 @@ test "file sink availability reflects backend support" {
 ///|
 test "file sink unavailable backend keeps stable fallback state" {
   let sink = file_sink(
-    "bitlogger-unavailable.log",
+    "logs/bitlogger-unavailable.log",
     rotation=Some(file_rotation(64, max_backups=2)),
   )
   if sink.is_available() {
@@ -73,7 +73,10 @@ test "file sink rotation config normalizes invalid inputs" {
   let rotation = file_rotation(0, max_backups=0)
   inspect(rotation.max_bytes, content="1")
   inspect(rotation.max_backups, content="1")
-  let sink = file_sink("bitlogger-rotation-config.log", rotation=Some(rotation))
+  let sink = file_sink(
+    "logs/bitlogger-rotation-config.log",
+    rotation=Some(rotation),
+  )
   inspect(sink.rotation_enabled(), content="true")
   match sink.rotation_config() {
     Some(config) => {
@@ -97,7 +100,7 @@ test "file rotation i64 preserves wide threshold metadata" {
 
 ///|
 test "file sink setters update auto flush and rotation state" {
-  let sink = file_sink("bitlogger-setters.log")
+  let sink = file_sink("logs/bitlogger-setters.log")
   let default_policy = sink.default_policy()
   inspect(sink.append_mode(), content="true")
   inspect(sink.auto_flush_enabled(), content="true")
@@ -146,7 +149,7 @@ test "file sink setters update auto flush and rotation state" {
 ///|
 test "file sink reset policy restores configured defaults" {
   let sink = file_sink(
-    "bitlogger-reset-policy.log",
+    "logs/bitlogger-reset-policy.log",
     append=false,
     auto_flush=false,
     rotation=Some(file_rotation(24, max_backups=3)),
@@ -173,7 +176,7 @@ test "file sink reset policy restores configured defaults" {
 
 ///|
 test "file sink set policy applies bundled runtime policy" {
-  let sink = file_sink("bitlogger-set-policy.log")
+  let sink = file_sink("logs/bitlogger-set-policy.log")
   let default_policy = sink.default_policy()
   sink.set_policy(
     FileSinkPolicy::new(

src/formatting/formatter.mbt

@@ -55,7 +55,7 @@ fn normalize_style_tag_name(name : String) -> String {
 
 ///|
 pub fn style_tag_registry() -> StyleTagRegistry {
-  { entries: {} }
+  { entries: Map([]) }
 }
 
 ///|
@@ -1015,7 +1015,7 @@ fn level_ansi_code(level : @core.Level) -> String {
 
 ///|
 fn fields_to_json(fields : Array[@core.Field]) -> Json {
-  let obj : Map[String, Json] = {}
+  let obj : Map[String, Json] = Map([])
   for item in fields {
     obj[item.key] = Json::string(item.value)
   }

src/library_logger_builder_test.mbt

@@ -164,7 +164,10 @@ test "library logger builder unwrap preserves file runtime helpers" {
   let config = LoggerConfig::new(
     min_level=Level::Warn,
     target="lib.file.same-build",
-    sink=SinkConfig::new(kind=SinkKind::File, path="lib-file-same-build.log"),
+    sink=SinkConfig::new(
+      kind=SinkKind::File,
+      path="logs/lib-file-same-build.log",
+    ),
     queue=Some(QueueConfig::new(2, overflow=QueueOverflowPolicy::DropOldest)),
   )
   let logger = build_library_logger(config)
@@ -236,7 +239,7 @@ test "library logger builder unwrap preserves file controls" {
     target="lib.file.controls.same-build",
     sink=SinkConfig::new(
       kind=SinkKind::File,
-      path="lib-file-controls-same-build.log",
+      path="logs/lib-file-controls-same-build.log",
     ),
   )
   let logger = build_library_logger(config)

src/logger_config_json_helpers_test.mbt

@@ -30,7 +30,7 @@ test "config subtype json helpers stringify stable shapes" {
     stringify_sink_config(
       SinkConfig::new(
         kind=SinkKind::File,
-        path="demo.log",
+        path="logs/demo.log",
         append=false,
         auto_flush=false,
         rotation=Some(file_rotation(128, max_backups=2)),
@@ -40,7 +40,7 @@ test "config subtype json helpers stringify stable shapes" {
         ),
       ),
     ),
-    content="{\"kind\":\"file\",\"path\":\"demo.log\",\"append\":false,\"auto_flush\":false,\"text_formatter\":{\"show_timestamp\":false,\"show_level\":true,\"show_target\":true,\"show_fields\":true,\"separator\":\" \",\"field_separator\":\" \",\"template\":\"\",\"color_mode\":\"auto\",\"color_support\":\"truecolor\",\"style_markup\":\"full\",\"target_style_markup\":\"disabled\",\"fields_style_markup\":\"disabled\"},\"rotation\":{\"max_bytes\":128,\"max_backups\":2}}",
+    content="{\"kind\":\"file\",\"path\":\"logs/demo.log\",\"append\":false,\"auto_flush\":false,\"text_formatter\":{\"show_timestamp\":false,\"show_level\":true,\"show_target\":true,\"show_fields\":true,\"separator\":\" \",\"field_separator\":\" \",\"template\":\"\",\"color_mode\":\"auto\",\"color_support\":\"truecolor\",\"style_markup\":\"full\",\"target_style_markup\":\"disabled\",\"fields_style_markup\":\"disabled\"},\"rotation\":{\"max_bytes\":128,\"max_backups\":2}}",
   )
   inspect(
     @json_parser.stringify(
@@ -141,7 +141,7 @@ test "config json helpers export stable structured shapes" {
   let sink_json = sink_config_to_json(
     SinkConfig::new(
       kind=SinkKind::File,
-      path="demo.log",
+      path="logs/demo.log",
       append=false,
       auto_flush=false,
       rotation=Some(file_rotation(128, max_backups=2)),
@@ -161,7 +161,7 @@ test "config json helpers export stable structured shapes" {
   inspect(sink_obj.get("kind").unwrap().as_string().unwrap(), content="file")
   inspect(
     sink_obj.get("path").unwrap().as_string().unwrap(),
-    content="demo.log",
+    content="logs/demo.log",
   )
   inspect(sink_obj.get("append").unwrap().as_bool().unwrap(), content="false")
   inspect(

src/logger_config_parser_test.mbt

@@ -45,7 +45,7 @@ test "logger config parser reads formatter and queue options" {
 ///|
 test "logger config parser reads file rotation options" {
   let config = parse_logger_config_text(
-    "{\"sink\":{\"kind\":\"file\",\"path\":\"bitlogger.log\",\"rotation\":{\"max_bytes\":128,\"max_backups\":3}}}",
+    "{\"sink\":{\"kind\":\"file\",\"path\":\"logs/bitlogger.log\",\"rotation\":{\"max_bytes\":128,\"max_backups\":3}}}",
   )
   inspect(
     match config.sink.kind {
@@ -54,7 +54,7 @@ test "logger config parser reads file rotation options" {
     },
     content="File",
   )
-  inspect(config.sink.path, content="bitlogger.log")
+  inspect(config.sink.path, content="logs/bitlogger.log")
   match config.sink.rotation {
     Some(rotation) => {
       inspect(rotation.max_bytes, content="128")
@@ -68,9 +68,9 @@ test "logger config parser reads file rotation options" {
 ///|
 test "logger config parser prefers max_bytes_i64 when present" {
   let config = parse_logger_config_text(
-    "{\"sink\":{\"kind\":\"file\",\"path\":\"bitlogger.log\",\"rotation\":{\"max_bytes\":128,\"max_bytes_i64\":\"4294967296\",\"max_backups\":3}}}",
+    "{\"sink\":{\"kind\":\"file\",\"path\":\"logs/bitlogger.log\",\"rotation\":{\"max_bytes\":128,\"max_bytes_i64\":\"4294967296\",\"max_backups\":3}}}",
   )
-  inspect(config.sink.path, content="bitlogger.log")
+  inspect(config.sink.path, content="logs/bitlogger.log")
   match config.sink.rotation {
     Some(rotation) => {
       inspect(rotation.max_bytes, content="2147483647")

src/logger_config_rotation_test.mbt

@@ -43,13 +43,13 @@ test "logger config stringify roundtrips file rotation fields" {
     LoggerConfig::new(
       sink=SinkConfig::new(
         kind=SinkKind::File,
-        path="bitlogger.log",
+        path="logs/bitlogger.log",
         rotation=Some(file_rotation(256, max_backups=2)),
       ),
     ),
   )
   let config = parse_logger_config_text(text)
-  inspect(config.sink.path, content="bitlogger.log")
+  inspect(config.sink.path, content="logs/bitlogger.log")
   match config.sink.rotation {
     Some(rotation) => {
       inspect(rotation.max_bytes, content="256")
@@ -66,13 +66,13 @@ test "logger config stringify roundtrips file rotation i64 metadata" {
     LoggerConfig::new(
       sink=SinkConfig::new(
         kind=SinkKind::File,
-        path="bitlogger.log",
+        path="logs/bitlogger.log",
         rotation=Some(file_rotation_i64(4294967296L, max_backups=2)),
       ),
     ),
   )
   let config = parse_logger_config_text(text)
-  inspect(config.sink.path, content="bitlogger.log")
+  inspect(config.sink.path, content="logs/bitlogger.log")
   match config.sink.rotation {
     Some(rotation) => {
       inspect(rotation.max_bytes, content="2147483647")

src/parsed_application_logger_test.mbt

@@ -147,7 +147,7 @@ test "application logger parse-build matches parsed direct builder behavior" {
 ///|
 test "parsed application logger keeps direct runtime helper surface" {
   let logger : ApplicationLogger = parse_and_build_application_logger(
-    "{\"min_level\":\"warn\",\"target\":\"app.json.helpers\",\"queue\":{\"max_pending\":2,\"overflow\":\"DropOldest\"},\"sink\":{\"kind\":\"file\",\"path\":\"app-json-helpers.log\"}}",
+    "{\"min_level\":\"warn\",\"target\":\"app.json.helpers\",\"queue\":{\"max_pending\":2,\"overflow\":\"DropOldest\"},\"sink\":{\"kind\":\"file\",\"path\":\"logs/app-json-helpers.log\"}}",
   )
 
   logger.error("one")

src/parsed_library_logger_test.mbt

@@ -143,7 +143,7 @@ test "library logger parse-build unwrap matches parsed direct builder behavior"
 
 ///|
 test "library logger parse-build unwrap preserves file runtime helpers" {
-  let raw = "{\"min_level\":\"warn\",\"target\":\"lib.json.file.same-build\",\"queue\":{\"max_pending\":2,\"overflow\":\"DropOldest\"},\"sink\":{\"kind\":\"file\",\"path\":\"lib-json-file-same-build.log\"}}"
+  let raw = "{\"min_level\":\"warn\",\"target\":\"lib.json.file.same-build\",\"queue\":{\"max_pending\":2,\"overflow\":\"DropOldest\"},\"sink\":{\"kind\":\"file\",\"path\":\"logs/lib-json-file-same-build.log\"}}"
   let logger = parse_and_build_library_logger(raw)
   let full = logger.to_logger()
   let configured = parse_and_build_logger(raw)
@@ -208,7 +208,7 @@ test "library logger parse-build unwrap preserves file runtime helpers" {
 
 ///|
 test "library logger parse-build unwrap preserves file controls" {
-  let raw = "{\"min_level\":\"warn\",\"target\":\"lib.json.file.controls.same-build\",\"sink\":{\"kind\":\"file\",\"path\":\"lib-json-file-controls-same-build.log\"}}"
+  let raw = "{\"min_level\":\"warn\",\"target\":\"lib.json.file.controls.same-build\",\"sink\":{\"kind\":\"file\",\"path\":\"logs/lib-json-file-controls-same-build.log\"}}"
   let logger = parse_and_build_library_logger(raw)
   let full = logger.to_logger()
   let configured = parse_and_build_logger(raw)

src/presets_test.mbt

@@ -40,7 +40,7 @@ test "logger config presets use expected defaults" {
 
 ///|
 test "file preset uses file sink defaults" {
-  let config = file("bitlogger.log")
+  let config = file("logs/bitlogger.log")
   inspect(config.min_level.label(), content="INFO")
   inspect(config.target, content="")
   inspect(config.timestamp, content="false")
@@ -51,7 +51,7 @@ test "file preset uses file sink defaults" {
     },
     content="File",
   )
-  inspect(config.sink.path, content="bitlogger.log")
+  inspect(config.sink.path, content="logs/bitlogger.log")
   inspect(config.sink.append, content="true")
   inspect(config.sink.auto_flush, content="true")
   inspect(config.sink.rotation is None, content="true")
@@ -86,7 +86,7 @@ test "preset helpers compose queue and file rotation without losing config" {
     separator=" | ",
   )
   let config = file(
-    "service.log",
+    "logs/service.log",
     min_level=Level::Warn,
     target="svc.worker",
     timestamp=true,
@@ -102,7 +102,7 @@ test "preset helpers compose queue and file rotation without losing config" {
   inspect(config.min_level.label(), content="WARN")
   inspect(config.target, content="svc.worker")
   inspect(config.timestamp, content="true")
-  inspect(config.sink.path, content="service.log")
+  inspect(config.sink.path, content="logs/service.log")
   inspect(config.sink.append, content="false")
   inspect(config.sink.auto_flush, content="false")
   inspect(config.sink.text_formatter.show_timestamp, content="false")
@@ -132,11 +132,15 @@ test "preset helpers compose queue and file rotation without losing config" {
 ///|
 test "queue helper preserves file rotation when applied after rotation" {
   let config = with_queue(
-    with_file_rotation(file("service.log", append=false), 256, max_backups=2),
+    with_file_rotation(
+      file("logs/service.log", append=false),
+      256,
+      max_backups=2,
+    ),
     max_pending=8,
     overflow=QueueOverflowPolicy::DropNewest,
   )
-  inspect(config.sink.path, content="service.log")
+  inspect(config.sink.path, content="logs/service.log")
   inspect(config.sink.append, content="false")
   match config.queue {
     Some(queue) => {
@@ -163,11 +167,11 @@ test "queue helper preserves file rotation when applied after rotation" {
 ///|
 test "file rotation i64 helper preserves file preset shape" {
   let config = with_file_rotation_i64(
-    with_queue(file("service.log", append=false), max_pending=8),
+    with_queue(file("logs/service.log", append=false), max_pending=8),
     4294967296L,
     max_backups=2,
   )
-  inspect(config.sink.path, content="service.log")
+  inspect(config.sink.path, content="logs/service.log")
   inspect(config.sink.append, content="false")
   match config.sink.rotation {
     Some(rotation) => {

src/runtime_file_json_test.mbt

@@ -29,7 +29,7 @@ test "file state json helpers stringify stable snapshots" {
 
   let plain = file_sink_state_to_json(
     FileSinkState::new(
-      "demo.log",
+      "logs/demo.log",
       available=true,
       append=false,
       auto_flush=true,
@@ -48,11 +48,11 @@ test "file state json helpers stringify stable snapshots" {
     .unwrap()
   inspect(
     @json_parser.stringify(plain),
-    content="{\"path\":\"demo.log\",\"available\":true,\"append\":false,\"auto_flush\":true,\"open_failures\":1,\"write_failures\":2,\"flush_failures\":3,\"rotation_failures\":4,\"rotation\":{\"max_bytes\":64,\"max_backups\":2}}",
+    content="{\"path\":\"logs/demo.log\",\"available\":true,\"append\":false,\"auto_flush\":true,\"open_failures\":1,\"write_failures\":2,\"flush_failures\":3,\"rotation_failures\":4,\"rotation\":{\"max_bytes\":64,\"max_backups\":2}}",
   )
   inspect(
     plain_obj.get("path").unwrap().as_string().unwrap(),
-    content="demo.log",
+    content="logs/demo.log",
   )
   inspect(
     plain_obj.get("available").unwrap().as_bool().unwrap(),
@@ -90,7 +90,7 @@ test "file state json helpers stringify stable snapshots" {
 
   let wide = file_sink_state_to_json(
     FileSinkState::new(
-      "wide.log",
+      "logs/wide.log",
       available=true,
       append=true,
       auto_flush=false,
@@ -132,7 +132,7 @@ test "file state json helpers stringify stable snapshots" {
   inspect(
     stringify_file_sink_state(
       FileSinkState::new(
-        "plain.log",
+        "logs/plain.log",
         available=false,
         append=true,
         auto_flush=false,
@@ -143,7 +143,7 @@ test "file state json helpers stringify stable snapshots" {
         rotation_failures=0,
       ),
     ),
-    content="{\"path\":\"plain.log\",\"available\":false,\"append\":true,\"auto_flush\":false,\"open_failures\":0,\"write_failures\":0,\"flush_failures\":0,\"rotation_failures\":0,\"rotation\":null}",
+    content="{\"path\":\"logs/plain.log\",\"available\":false,\"append\":true,\"auto_flush\":false,\"open_failures\":0,\"write_failures\":0,\"flush_failures\":0,\"rotation_failures\":0,\"rotation\":null}",
   )
 }
 
@@ -152,7 +152,7 @@ test "runtime file state json helpers stringify queue snapshots" {
   let runtime_json = runtime_file_state_to_json(
     RuntimeFileState::new(
       FileSinkState::new(
-        "queue.log",
+        "logs/queue.log",
         available=true,
         append=true,
         auto_flush=false,
@@ -180,7 +180,7 @@ test "runtime file state json helpers stringify queue snapshots" {
   )
   inspect(
     runtime_file_obj.get("path").unwrap().as_string().unwrap(),
-    content="queue.log",
+    content="logs/queue.log",
   )
   inspect(
     runtime_file_obj.get("available").unwrap().as_bool().unwrap(),
@@ -194,7 +194,7 @@ test "runtime file state json helpers stringify queue snapshots" {
   let json = stringify_runtime_file_state(
     RuntimeFileState::new(
       FileSinkState::new(
-        "queue.log",
+        "logs/queue.log",
         available=true,
         append=true,
         auto_flush=false,
@@ -211,13 +211,13 @@ test "runtime file state json helpers stringify queue snapshots" {
   )
   inspect(
     json,
-    content="{\"file\":{\"path\":\"queue.log\",\"available\":true,\"append\":true,\"auto_flush\":false,\"open_failures\":0,\"write_failures\":1,\"flush_failures\":2,\"rotation_failures\":3,\"rotation\":null},\"queued\":true,\"pending_count\":7,\"dropped_count\":5}",
+    content="{\"file\":{\"path\":\"logs/queue.log\",\"available\":true,\"append\":true,\"auto_flush\":false,\"open_failures\":0,\"write_failures\":1,\"flush_failures\":2,\"rotation_failures\":3,\"rotation\":null},\"queued\":true,\"pending_count\":7,\"dropped_count\":5}",
   )
 
   let wide_runtime_json = runtime_file_state_to_json(
     RuntimeFileState::new(
       FileSinkState::new(
-        "wide-queue.log",
+        "logs/wide-queue.log",
         available=true,
         append=true,
         auto_flush=true,

src/runtime_sink_close_test.mbt

@@ -16,7 +16,7 @@ test "configured logger close stays aligned with runtime sink close" {
 
   let file_config = LoggerConfig::new(
     target="config.close.file",
-    sink=SinkConfig::new(kind=SinkKind::File, path="config-close.log"),
+    sink=SinkConfig::new(kind=SinkKind::File, path="logs/config-close.log"),
   )
   let file_logger = build_logger(file_config)
   let file_sink = build_logger(file_config).sink
@@ -110,7 +110,7 @@ test "configured queued console close drains pending queue" {
 test "runtime sink queued file close drains queue before teardown" {
   let sink = RuntimeSink::QueuedFile(
     queued_sink(
-      file_sink("runtime-close-queued.log", auto_flush=false),
+      file_sink("logs/runtime-close-queued.log", auto_flush=false),
       max_pending=4,
     ),
   )

src/runtime_sink_file_controls_test.mbt

@@ -1,6 +1,6 @@
 ///|
 test "runtime sink plain file reopen helpers and failure resets work directly" {
-  let sink = RuntimeSink::File(file_sink("runtime-reopen-direct.log"))
+  let sink = RuntimeSink::File(file_sink("logs/runtime-reopen-direct.log"))
   if sink.file_available() {
     inspect(sink.close(), content="true")
     inspect(sink.file_reopen_append(), content="true")
@@ -52,7 +52,7 @@ test "runtime sink plain file reopen helpers and failure resets work directly" {
 ///|
 test "runtime sink queued file reopen helpers and failure resets work directly" {
   let sink = RuntimeSink::QueuedFile(
-    queued_sink(file_sink("runtime-reopen-queued.log"), max_pending=2),
+    queued_sink(file_sink("logs/runtime-reopen-queued.log"), max_pending=2),
   )
   if sink.file_available() {
     inspect(sink.file_close(), content="true")

src/runtime_sink_file_surface_test.mbt

@@ -7,7 +7,7 @@ test "runtime sink plain variants use documented fallback counts" {
   inspect(console_sink.drain(), content="0")
 
   let file_sink = RuntimeSink::File(
-    file_sink("runtime-direct.log", auto_flush=false),
+    file_sink("logs/runtime-direct.log", auto_flush=false),
   )
   inspect(file_sink.pending_count(), content="0")
   inspect(file_sink.dropped_count(), content="0")
@@ -81,17 +81,17 @@ test "runtime sink non-file variants expose documented file fallbacks" {
 test "runtime sink plain file helpers expose direct file state and policy" {
   let sink = RuntimeSink::File(
     file_sink(
-      "runtime-file-helpers.log",
+      "logs/runtime-file-helpers.log",
       auto_flush=false,
       rotation=Some(file_rotation(40, max_backups=2)),
     ),
   )
   inspect(sink.file_available() == native_files_supported(), content="true")
   match sink.file_path_or_none() {
-    Some(path) => inspect(path, content="runtime-file-helpers.log")
+    Some(path) => inspect(path, content="logs/runtime-file-helpers.log")
     None => inspect(false, content="true")
   }
-  inspect(sink.file_path(), content="runtime-file-helpers.log")
+  inspect(sink.file_path(), content="logs/runtime-file-helpers.log")
   inspect(sink.file_append_mode(), content="true")
   inspect(sink.file_auto_flush(), content="false")
   inspect(sink.file_rotation_enabled(), content="true")
@@ -125,14 +125,14 @@ test "runtime sink plain file helpers expose direct file state and policy" {
   }
   match sink.file_state_or_none() {
     Some(snapshot) => {
-      inspect(snapshot.path, content="runtime-file-helpers.log")
+      inspect(snapshot.path, content="logs/runtime-file-helpers.log")
       inspect(snapshot.append, content="true")
       inspect(snapshot.auto_flush, content="false")
     }
     None => inspect(false, content="true")
   }
   let state = sink.file_state()
-  inspect(state.path, content="runtime-file-helpers.log")
+  inspect(state.path, content="logs/runtime-file-helpers.log")
   inspect(state.available == sink.file_available(), content="true")
   inspect(state.append, content="true")
   inspect(state.auto_flush, content="false")
@@ -141,7 +141,7 @@ test "runtime sink plain file helpers expose direct file state and policy" {
       inspect(snapshot.queued, content="false")
       inspect(snapshot.pending_count, content="0")
       inspect(snapshot.dropped_count, content="0")
-      inspect(snapshot.file.path, content="runtime-file-helpers.log")
+      inspect(snapshot.file.path, content="logs/runtime-file-helpers.log")
     }
     None => inspect(false, content="true")
   }
@@ -170,7 +170,7 @@ test "runtime sink plain file helpers expose direct file state and policy" {
 test "runtime sink queued file helpers preserve queue-aware file runtime state" {
   let sink = RuntimeSink::QueuedFile(
     queued_sink(
-      file_sink("runtime-queued-file.log", auto_flush=false),
+      file_sink("logs/runtime-queued-file.log", auto_flush=false),
       max_pending=2,
       overflow=QueueOverflowPolicy::DropNewest,
     ),
@@ -185,10 +185,10 @@ test "runtime sink queued file helpers preserve queue-aware file runtime state"
   logger.info("three")
   inspect(sink.file_available() == native_files_supported(), content="true")
   match sink.file_path_or_none() {
-    Some(path) => inspect(path, content="runtime-queued-file.log")
+    Some(path) => inspect(path, content="logs/runtime-queued-file.log")
     None => inspect(false, content="true")
   }
-  inspect(sink.file_path(), content="runtime-queued-file.log")
+  inspect(sink.file_path(), content="logs/runtime-queued-file.log")
   inspect(sink.file_policy_or_none() is None, content="false")
   inspect(sink.file_default_policy_or_none() is None, content="false")
   inspect(sink.file_state_or_none() is None, content="false")
@@ -199,7 +199,7 @@ test "runtime sink queued file helpers preserve queue-aware file runtime state"
       inspect(snapshot.queued, content="true")
       inspect(snapshot.pending_count, content="2")
       inspect(snapshot.dropped_count, content="1")
-      inspect(snapshot.file.path, content="runtime-queued-file.log")
+      inspect(snapshot.file.path, content="logs/runtime-queued-file.log")
     }
     None => inspect(false, content="true")
   }

src/runtime_sink_progress_test.mbt

@@ -111,7 +111,7 @@ test "runtime sink progress helpers expose queue and plain file steps separately
   inspect(queued_progress.file_backed, content="false")
 
   let file_sink = RuntimeSink::File(
-    file_sink("runtime-progress-direct.log", auto_flush=false),
+    file_sink("logs/runtime-progress-direct.log", auto_flush=false),
   )
   let file_progress = file_sink.flush_progress()
   inspect(file_progress.queue_advanced_count, content="0")

src/utils/file_backend_stub.mbt

@@ -12,6 +12,12 @@ pub fn open_file_handle_internal(path : String, append : Bool) -> FileHandle? {
   None
 }
 
+///|
+pub fn file_exists_internal(path : String) -> Bool {
+  ignore(path)
+  false
+}
+
 ///|
 pub fn write_file_handle_internal(
   handle : FileHandle,

src/utils/pkg.generated.mbti

@@ -25,6 +25,8 @@ pub fn default_style_tag_registry() -> @formatting.StyleTagRegistry
 
 pub fn field_equals(String, String) -> (@core.Record) -> Bool
 
+pub fn file_exists_internal(String) -> Bool
+
 pub fn file_size_i64_internal(FileHandle) -> Int64
 
 pub fn flush_file_handle_internal(FileHandle) -> Bool

version

@@ -1 +0,0 @@
-trueVersion = "1.0.0"