📝 Fix policy test and doc

docs/api/configured-logger-file-path-or-none.md

@@ -0,0 +1,79 @@
+---
+name: configured-logger-file-path-or-none
+group: api
+category: runtime
+update-time: 20260707
+description: Read the effective file path from a ConfiguredLogger only when it is actually file-backed.
+key-word:
+    - logger
+    - runtime
+    - file
+    - truthful
+---
+
+## Configured-logger-file-path-or-none
+
+Read the effective file path from a `ConfiguredLogger` only when it is actually file-backed.
+
+This is the truthful companion to `file_path()`. Prefer it for diagnostics, branching, and recovery logic that must distinguish “not file-backed” from compatibility fallbacks.
+
+### Interface
+
+```moonbit
+pub fn ConfiguredLogger::file_path_or_none(self : ConfiguredLogger) -> String? {}
+```
+
+#### input
+
+- `self : ConfiguredLogger` - Config-driven runtime logger whose file path should be inspected.
+
+#### output
+
+- `String?` - `Some(path)` when the configured sink is file-backed, otherwise `None`.
+
+### Explanation
+
+Detailed rules explaining key parameters and behaviors
+
+- File-backed sinks return `Some(path)` through the wrapped `RuntimeSink`.
+- Queued file sinks forward the wrapped inner file sink path as `Some(path)`.
+- Non-file sinks return `None`.
+- This helper is observation-only and does not mutate logger state.
+
+### How to Use
+
+Here are some specific examples provided.
+
+#### When Need Truthful File-backed Detection
+
+When code should branch only if file semantics really exist:
+```moonbit
+match logger.file_path_or_none() {
+  Some(path) => println(path)
+  None => ()
+}
+```
+
+In this example, `None` means the configured logger is not file-backed.
+
+#### When Need Path Diagnostics Without Fallback Values
+
+When support output should avoid compatibility placeholders:
+```moonbit
+let maybe_path = logger.file_path_or_none()
+```
+
+In this example, callers can keep “no file semantics” distinct from a real path.
+
+### Error Case
+
+e.g.:
+- If the configured sink is not file-backed, the method returns `None`.
+
+- If callers need the broader file snapshot or queue context, prefer `file_state_or_none()` or `file_runtime_state()`.
+
+### Notes
+
+1. Prefer this helper over `file_path()` for truthful runtime diagnostics.
+
+2. `file_path()` remains available as the compatibility fallback API.