📝 Add configured logger file runtime API docs

docs/api/configured-logger-file-reopen.md

@@ -0,0 +1,75 @@
+---
+name: configured-logger-file-reopen
+group: api
+category: runtime
+update-time: 20260512
+description: Reopen the file sink behind a configured runtime logger with an optional append-mode override.
+key-word:
+    - logger
+    - runtime
+    - file
+    - public
+---
+
+## Configured-logger-file-reopen
+
+Reopen the file sink behind a `ConfiguredLogger`. This helper is useful for recovery flows after file unavailability or policy changes.
+
+### Interface
+
+```moonbit
+pub fn ConfiguredLogger::file_reopen(self : ConfiguredLogger, append~ : Bool? = None) -> Bool {}
+```
+
+#### input
+
+- `self : ConfiguredLogger` - Config-driven runtime logger whose file sink should be reopened.
+- `append : Bool?` - Optional append-mode override used for reopen behavior.
+
+#### output
+
+- `Bool` - Whether reopen succeeded.
+
+### Explanation
+
+Detailed rules explaining key parameters and behaviors
+
+- Plain file sinks reopen directly.
+- Queued file sinks forward reopen behavior to the wrapped file sink.
+- `append=None` preserves current reopen policy, while `Some(true/false)` overrides append mode.
+- Non-file sinks return `false`.
+
+### How to Use
+
+Here are some specific examples provided.
+
+#### When Need Recovery After File Failure
+
+When application code should attempt to restore file logging:
+```moonbit
+ignore(logger.file_reopen())
+```
+
+In this example, the configured logger tries to reopen its runtime file sink using current policy.
+
+#### When Need Explicit Append-mode Reopen
+
+When recovery should choose append or truncate behavior explicitly:
+```moonbit
+let ok = logger.file_reopen(append=Some(true))
+```
+
+In this example, reopen behavior is directed by the call site.
+
+### Error Case
+
+e.g.:
+- If the configured sink is not file-backed, the method returns `false`.
+
+- If callers only need the current configured policy, `file_reopen_with_current_policy()` may be the clearer API.
+
+### Notes
+
+1. Use this helper for explicit recovery flows.
+
+2. Pair it with `file_available()` and failure counters when diagnosing reopen behavior.