chore(quest): plan a box's clone_from, and a vector's AsRef and AsMut

quest/m3/README.md

@@ -42,3 +42,4 @@ generic std gap is planned here even when moq never calls it.
 - [Fresh writes through a zip, a copy, and a repeat](/quest/m3/ts-fresh-shapes.md) - zipping a `Vec<[T; N]>`, reading a `T` out of `Zip::next`, and `copied` or `vec![x; n]` over a `Copy` type translate
 - [Python's wake on the loop's own thread](/quest/m3/ffi-python-wake.md) - a wake on the event loop's thread resumes the future with no socket pair
 - [Python's call cost](/quest/m3/ffi-python-calls.md) - a call on an object costs what BoltFFI's does, or the gap is explained
+- [A box's clone_from, and a vector's AsRef and AsMut](/quest/m3/ts-box-vec-conversions.md) - `clone_from` of a `Box<String>` and `AsRef<[T]>` of a `Vec` translate

quest/m3/ts-box-vec-conversions.md

@@ -0,0 +1,16 @@
+# [S] A box's clone_from, and a vector's AsRef and AsMut
+
+## Goal
+
+[rust2-ts](/ts/README.md) translates `Clone::clone_from` of a `Box<T>` whose `T` needs a
+drop, such as `Box<String>`, dropping the old value where std's does, and `AsRef<[T]>` and
+`AsMut<[T]>` of a `Vec<T>`, proven by differential tests against native Rust.
+
+## Plan
+
+Found by [#387](https://github.com/moq-dev/rust2/pull/387) after
+[#386](https://github.com/moq-dev/rust2/pull/386) added a general `clone_from` rule, which
+refuses a `Box<T>` whose `T` needs a drop, and `AsRef` and `AsMut` as a slice for arrays only.
+No consumer calls them yet; they are planned here as part of std.
+
+Public API: the translator's output.