✨ Add file policy JSON export helpers

bitlogger/BitLogger_test.mbt

@@ -301,6 +301,27 @@ test "runtime file state json helpers stringify queue snapshots" {
   )
 }
 
+test "file sink policy json helpers stringify stable policies" {
+  inspect(
+    @json_parser.stringify(
+      file_sink_policy_to_json(
+        FileSinkPolicy::new(
+          append=false,
+          auto_flush=true,
+          rotation=Some(file_rotation(96, max_backups=3)),
+        ),
+      ),
+    ),
+    content="{\"append\":false,\"auto_flush\":true,\"rotation\":{\"max_backups\":3,\"max_bytes\":96}}",
+  )
+  inspect(
+    stringify_file_sink_policy(
+      FileSinkPolicy::new(append=true, auto_flush=false, rotation=None),
+    ),
+    content="{\"append\":true,\"auto_flush\":false,\"rotation\":null}",
+  )
+}
+
 test "configured logger reports disabled rotation when file sink has none" {
   let logger = build_logger(
     LoggerConfig::new(

bitlogger/README.mbt.md

@@ -247,6 +247,7 @@ test {
 - `set_policy(...)` applies append, auto-flush, and rotation as a bundled runtime update / `set_policy(...)` 可将 append、auto-flush、rotation 作为一组运行期策略一次性写回
 - `reset_failure_counters()` clears the open/write/flush/rotation counters after diagnostics or recovery / `reset_failure_counters()` 可在排障或恢复后清空 open/write/flush/rotation 失败计数
 - `reset_policy()` restores append, auto-flush, and rotation back to the sink's original defaults / `reset_policy()` 可将 append、auto-flush、rotation 恢复到 sink 初始默认策略
+- `file_sink_policy_to_json(...)` / `stringify_file_sink_policy(...)` also export standalone file policy snapshots as JSON / `file_sink_policy_to_json(...)` / `stringify_file_sink_policy(...)` 也可将独立 file policy 快照直接导出为 JSON
 - `file_sink_state_to_json(...)` / `stringify_file_sink_state(...)` and `runtime_file_state_to_json(...)` / `stringify_runtime_file_state(...)` export snapshots as JSON / `file_sink_state_to_json(...)` / `stringify_file_sink_state(...)` 与 `runtime_file_state_to_json(...)` / `stringify_runtime_file_state(...)` 可将快照直接导出为 JSON
 - `set_auto_flush(...)`, `set_rotation(...)`, and `clear_rotation()` allow runtime tuning of core file sink policies / `set_auto_flush(...)`、`set_rotation(...)`、`clear_rotation()` 可在运行期调整 file sink 的基础策略
 - `open_failures()`、`write_failures()`、`flush_failures()`、`rotation_failures()` expose basic sink health counters / `open_failures()`、`write_failures()`、`flush_failures()`、`rotation_failures()` 可用于观察基础 sink 健康状态

bitlogger/config.mbt

@@ -153,6 +153,31 @@ pub fn RuntimeFileState::new(
   { file, queued, pending_count, dropped_count }
 }
 
+fn file_sink_policy_to_json_value(policy : FileSinkPolicy) -> @json_parser.JsonValue {
+  let obj : Map[String, @json_parser.JsonValue] = {
+    "append": @json_parser.JsonValue::Bool(policy.append),
+    "auto_flush": @json_parser.JsonValue::Bool(policy.auto_flush),
+  }
+  match policy.rotation {
+    None => obj["rotation"] = @json_parser.JsonValue::Null
+    Some(rotation) => obj["rotation"] = file_rotation_config_to_json(rotation)
+  }
+  @json_parser.JsonValue::Object(obj)
+}
+
+pub fn file_sink_policy_to_json(policy : FileSinkPolicy) -> @json_parser.JsonValue {
+  file_sink_policy_to_json_value(policy)
+}
+
+pub fn stringify_file_sink_policy(policy : FileSinkPolicy, pretty~ : Bool = false) -> String {
+  let value = file_sink_policy_to_json_value(policy)
+  if pretty {
+    @json_parser.stringify_pretty(value, 2)
+  } else {
+    @json_parser.stringify(value)
+  }
+}
+
 fn file_sink_state_to_json_value(state : FileSinkState) -> @json_parser.JsonValue {
   let obj : Map[String, @json_parser.JsonValue] = {
     "path": @json_parser.JsonValue::String(state.path),