Record the refcount removal beside the sweep that raised it

docs/HANDOFF.md

@@ -6,10 +6,10 @@ found is in `docs/LAYOUT_LOG.md`.
 
 ## A sweep for allocation, and the cost per child, is on #19
 
-The fourteenth sweep landed at `97fca76`. It read the whole branch again,
+The fourteenth sweep landed at `97fca76`, with the refcount removal below at
-aimed first at what allocates and then at whatever the reading turned up.
+`429a4f1`. It read the whole branch again, aimed first at what allocates and
-Eight findings, the largest two both about cost per thing rather than per
+then at whatever the reading turned up. Nine findings, the largest two both
-frame:
+about cost per thing rather than per frame:
 
 - **A container's draw was quadratic in its children.** Five per-child steps
   each asked "have I done this one already?" by searching a list; at 1,600
@@ -38,14 +38,21 @@ changed; and two comments this branch's own commits falsified -- one saying
 `widget_trait!` takes no attributes after `76aaf06` taught it to, one saying
 `Scroll` clips when masking is a capability a caller opts into with `Masked`.
 
+The ninth is the one Bryan asked for on 2026-09-21, having first been left for
+the pre-gate pass: `StrongWidget` allocated a `RefCounter(Arc<AtomicU32>)` it
+could never use, since it deliberately has no `Clone`, so every widget paid a
+heap allocation and two atomic read-modify-writes for a count that stayed at
+zero. It is the id, the sender and the type now, and `Drop` sends;
+`size_of::<StrongWidget>()` is 32 rather than 40. `RefCounter` stays for
+`TextureHandle`, which does clone, trimmed to what that needs.
+
 It also left five things, with the numbers. Text allocates about six times per
 re-broken paragraph per frame, and removing all of them is **0.07%** of
 instructions (3.7107B to 3.7081B over 500 sweeping resize frames of 40
 paragraphs), so the count is recorded rather than the machinery built --
 allocation count and cost are not the same quantity, and this is where they
-part. `StrongWidget` carries an `Arc<AtomicU32>` it can never use, since it has
+part. Seven dead items older than #19 are listed under the pre-gate review
-no `Clone`; that and seven dead items older than #19 are listed under the
+below rather than fixed here.
-pre-gate review below rather than fixed here.
 
 `docs/LAYOUT_LOG.md` has all of it. Verified: format, clippy both ways, 190
 ordinary, 193 diagnostic and 189 release tests, the cold dump byte-identical to
@@ -287,9 +294,10 @@ comparison work above, its review rounds past `cadfba0` are described in
 - **A full sweep of the branch**, `cbccfb6` -- a length of zero that printed
   as nothing, a ceiling that stepped off the top of the grid, and a harness
   setter that dropped the bound beside the length it set.
-- **A sweep for allocation and the cost per child**, `97fca76` -- a
+- **A sweep for allocation and the cost per child**, `97fca76` and `429a4f1`
-  container's draw quadratic in its children, and a mask's rectangle resolved
+  -- a container's draw quadratic in its children, a mask's rectangle resolved
-  once per fragment. Described at the top of this file.
+  once per fragment, and the refcount a widget handle can never raise.
+  Described at the top of this file.
 
 The settled design of the vocabulary rounds is in `docs/LAYOUT.md` under
 "Three names, and the one argument that says them". Bryan settled the API
@@ -401,13 +409,9 @@ a compile error, which reads exactly like a fuzzer failure.
    grammars of which `core/src/util/vec2.rs` uses two, one line apart.
    `Align` now has `Index<Axis>`, so the `if let Some` each
    `partial_align` writes twice collapses when that sweep reaches them.
-   The fourteenth sweep adds more: `StrongWidget` allocates an
+   The fourteenth sweep adds more, all dead: `Size::to_uivec2`, `Size::rel`,
-   `Arc<AtomicU32>` refcount it can never use, because it deliberately has no
+   `Size::leftover`, `Len::to_uivec2`, `Vec2::with_x`, `Vec2::with_y`,
-   `Clone`, so every widget pays a heap allocation and two atomic
+   `Vec2::ceil` and `Layers::iter_orderless_mut`.
-   read-modify-writes for a count that stays at zero, and `StrongWidget::refs`
-   has no caller; and `Size::to_uivec2`, `Size::rel`, `Size::leftover`,
-   `Len::to_uivec2`, `Vec2::with_x`, `Vec2::with_y`, `Vec2::ceil` and
-   `Layers::iter_orderless_mut` are all dead.
 3. **Integrate the app's Iris capabilities before changing its pin.**
    `32f6ad8` has 45 commits not reachable from the review branch; shared UI
    ownership, richer masks, Android support, and app-side performance work

docs/LAYOUT_LOG.md

@@ -10,7 +10,7 @@ the current plan is in `docs/HANDOFF.md`.
 
 Over the whole branch again, aimed first at what allocates -- `Vec`s, `Arc`s,
 capacity dropped and re-grown -- and then at whatever else the reading turned
-up. Eight findings.
+up. Nine findings.
 
 - **A container's draw was quadratic in its children.** Every per-child step
   in one draw asked "have I done this one already?" by searching a list:
@@ -116,7 +116,24 @@ up. Eight findings.
   does not clip it, because masking is a capability a caller opts into by
   putting a `Masked` around it. The code is right; the reason was not.
 
-Five things the sweep **looked at and left**:
+- **`StrongWidget` carried a `RefCounter(Arc<AtomicU32>)` it could never
+  use.** It deliberately has no `Clone`, so the count never rose above zero,
+  `RefCounter::drop` always answered true, and `StrongWidget::refs` had no
+  caller -- while every widget made paid a heap allocation and every one
+  created or dropped paid two atomic read-modify-writes. Removed: the handle is
+  the id, the sender and the type, and `Drop` sends. It is 32 bytes rather than
+  40, and 40 rather than 48 for a `dyn` one. Raised as something to leave for
+  the pre-gate pass, `handle.rs` being outside #19, and Bryan asked for it here
+  (2026-09-21): not being `Clone` is what makes one handle the only one, which
+  is the same fact the child note above rests on.
+
+  `RefCounter` stays for `TextureHandle`, which does clone -- several widgets
+  showing one picture share its slot -- and is down to what that needs:
+  `quiet_clone` and `refs` had no callers at all, and `new` was `Default` spelt
+  out, so the default is derived now and says in one line that zero means one
+  handle.
+
+Four things the sweep **looked at and left**:
 
 - **Text allocates about six times per re-broken paragraph per frame**, and it
   is not worth removing. One is the whole text copied into the placement store
@@ -129,13 +146,6 @@ Five things the sweep **looked at and left**:
   is **0.07%**. The machinery is two pools and a changed `place` signature for
   that, so the count is recorded here instead. Allocation count is not the
   same quantity as cost, and this is where the two part.
-- **`StrongWidget` carries a `RefCounter(Arc<AtomicU32>)` it can never use.**
-  `StrongWidget` deliberately has no `Clone`, so the count never rises above
-  zero and `RefCounter::drop` always answers true -- but every widget still
-  allocates an `Arc`, and creating and dropping one is two atomic
-  read-modify-writes. `StrongWidget::refs` has no caller. `handle.rs` is
-  untouched by #19, so this belongs to the review of the code written before
-  the gate; recorded there.
 - **More for that same pass, all dead and all older than #19**:
   `Size::to_uivec2`, `Size::rel`, `Size::leftover`, `Len::to_uivec2`,
   `Vec2::with_x`, `Vec2::with_y`, `Vec2::ceil`, `Layers::iter_orderless_mut`.
@@ -151,6 +161,11 @@ Five things the sweep **looked at and left**:
   the duplication is bounded by what the caller wrote rather than by anything
   the arena does on its own.
 
+One more thing **looked at and left** in passing: `RefCounter` decrements with
+`Ordering::Release` and has no acquire on the last drop, which is the shape an
+`Arc` gets wrong when handles cross threads. Left because nothing here is
+threaded and the orderings are not this sweep's to guess at.
+
 Verified at the sweep's tip: format, workspace clippy under `-D warnings` with
 and without `layout-diagnostics`, **190** ordinary, **193** diagnostic and
 **189** release tests (188 and 191 before, with release failing), and the cold