📝 Update More API Document

docs/api/patch-sink.md

@@ -0,0 +1,66 @@
+---
+name: patch-sink
+group: api
+category: sink
+update-time: 20260520
+description: Create a sink that rewrites records with a patch before forwarding them.
+key-word:
+    - sink
+    - patch
+    - record
+    - public
+---
+
+## Patch-sink
+
+Create a sink that rewrites each record with a `RecordPatch` before forwarding it to another sink. This helper is the sink-level counterpart to `Logger::with_patch(...)`.
+
+### Interface
+
+```moonbit
+pub fn[S] patch_sink(sink : S, patch : RecordPatch) -> PatchSink[S] {
+```
+
+#### input
+
+- `sink : S` - Wrapped sink receiving patched records.
+- `patch : RecordPatch` - Record transformation applied before forwarding.
+
+#### output
+
+- `PatchSink[S]` - Patch-applying sink.
+
+### Explanation
+
+Detailed rules explaining key parameters and behaviors
+
+- Each record is transformed before it reaches the wrapped sink.
+- This helper is useful for sink-first composition graphs and adapters.
+- Use the logger-level helper when the patch should be attached after `Logger::new(...)` instead.
+
+### How to Use
+
+Here are some specific examples provided.
+
+#### When Need Record Rewriting At Sink Construction Time
+
+When sanitization or target rewriting should happen before sink delivery:
+```moonbit
+let sink = patch_sink(console_sink(), prefix_message("[safe] "))
+let logger = Logger::new(sink, target="auth")
+```
+
+In this example, records are patched before they are written to the wrapped sink.
+
+### Error Case
+
+e.g.:
+- If patching should be attached to an already-built logger, use `with_patch(...)` instead.
+
+- Patch behavior is defined by the supplied function, so semantic mistakes come from patch logic rather than sink mechanics.
+
+### Notes
+
+1. This helper is useful for explicit sink graphs.
+
+2. It composes naturally with helpers such as `compose_patches(...)`.