quest: plan operator trait methods called by path

quest/m3/README.md

@@ -38,6 +38,7 @@ generic std gap is planned here even when moq never calls it.
 - [A B-tree's searches call Ord as std's do](/quest/m3/ts-btree-search-order.md) - a B-tree's lookups and inserts call a key's own `Ord` in std's order and number
 - [Rc and Arc of a slice](/quest/m3/ts-shared-slices.md) - `Rc<[T]>` and `Arc<[T]>` from a `Vec`, a slice, or an iterator translate
 - [Adding to a String](/quest/m3/ts-string-add.md) - `String + &str` translates as `+=` does
+- [Operator trait methods called by path](/quest/m3/ts-operator-paths.md) - `<u8 as AddAssign>::add_assign` and every other `std::ops` operator method translate called by path or as a value
 - [The rest of a vector's methods](/quest/m3/ts-vec-rest.md) - `append`, `resize`, `split_off`, `try_reserve`, and `Vec::from(VecDeque)` translate
 - [A reversed zip's per-pair cost](/quest/m3/ts-zip-rev-overhead.md) - a reversed by-index zip costs per pair what a forward one does, or the gap is explained
 - [Whole writes into a lazy cell or thread-local key](/quest/m3/ts-lazy-writes.md) - a whole write through a `&mut` to a `LazyCell`, `LazyLock`, or `LocalKey` keeps its state

quest/m3/ts-operator-paths.md

@@ -0,0 +1,27 @@
+# [S] Operator trait methods called by path
+
+## Goal
+
+[rust2-ts](/ts/README.md) translates each `std::ops` operator trait's method called by its
+path, such as `<u8 as AddAssign>::add_assign(&mut n, 1)` or `Add::add(a, b)`, wherever its
+operator form translates, as a written call and as a function value
+(`apply(AddAssign::add_assign, &mut n, 1)`). That covers every operator trait: the
+arithmetic, bitwise, and shift ones, their `*Assign` forms, `Neg`, and `Not`. A differential
+test against native Rust proves each call means what its operator does, overflow checks
+and integer widths included.
+
+## Plan
+
+Found on 2026-11-02 completing [moq-dev/rust2#470](https://github.com/moq-dev/rust2/pull/470):
+`<u8 as AddAssign>::add_assign` called by path is an "unsupported call", written or as a value,
+while `n += 1` translates. rustc lowers the operator on a primitive to a MIR binary op, but
+a call by path stays a call to the trait method, which no mapping covers.
+
+Lowering std's primitive impls from their MIR may cover most of these, since their bodies are
+the operator itself. Measure that against a mapping per trait.
+
+Public API: the translator's output.
+
+## Related
+
+- [Adding to a String](/quest/m3/ts-string-add.md) - `String + &str`, an operator impl of a std type rather than a primitive's