Record the bottom-up settle, and park two real defects on branches

Bryan's ordering replaces the stale-answer check with something the shape
of the frame makes impossible: nothing shallower is drawn while anything
deeper is dirty, so a parent never reads an answer that is about to move.

The other two are written up rather than landed. A stack takes its sizing
child's fraction twice, which no oracle can see because warm and cold are
wrong alike; the fix is three grid steps short of the tolerance. And
padding is to go outside what it pads with an `Inset` beside it, which one
unaccounted halving is holding up. Both are pushed as `wip/` branches.

docs/HANDOFF.md

@@ -10,7 +10,7 @@ stayed.
 
 Canonical Iris `main` is **`ca2b4b2`** (#17, the headless rig). **#18
 `split/18-position-chain`** is open in `/home/bob/repos/iris-pr18`, head
-**`c8beca5`**, pushed. It holds LAYOUT.md §2's position chain, `leftover`,
+**`a92c6ac`**, pushed. It holds LAYOUT.md §2's position chain, `leftover`,
 the `Holds` retained-layout contract, region nodes, built-in alignment and
 size rules, fixed-point layout, a box in pixels threaded down the draw, and
 a report read as a fraction of the containing widget. No PR review was
@@ -84,6 +84,14 @@ grid width fixes it; where it becomes visible is the shader's snap.
 
 ### A report is a fraction of the containing widget (landed, `ffd79f3`)
 
+**Superseded in part.** Bryan refined the rule twice on 2026-09-17: a
+fraction means whatever the *parent* says it means, and it need not even
+mean the same thing for two siblings -- "Main point is truly that rel is
+decided by parent". The span conclusion below is unchanged and the reason
+for it stands (a span's offer differs per child and the row does not), but
+`reports_of` is the wrong shape for saying it; see the parked padding
+branch.
+
 `rel(0.5)` is half the span whatever else is in it and wherever the child
 sits. A report used to come back composed through the box it was offered,
 and a span offers each child the room from its cursor, so a nested span
@@ -173,6 +181,82 @@ comes back as a box has to be rounded away from the measurement, not to the
 nearest step.** Rounding to nearest is right for a value being carried;
 it is wrong for a bound.
 
+### A frame settles strictly bottom-up (landed, `a92c6ac`)
+
+The queue was already deepest-first, but a widget that could not settle
+where it was called `redraw` on its parent from inside itself, which drew a
+shallow widget while dirty widgets deeper in other subtrees were still
+pending. A parent drawing over a subtree that has not settled reads answers
+about to move, and the one that settles does so inside the parent's draw --
+where its mark comes off and nothing compares what it now answers.
+
+A widget that cannot settle defers instead: it marks its parent, stays
+marked, and waits in `deferred` until the walk reaches the parent's depth,
+which cannot happen before everything deeper has settled.
+
+```rust
+loop {
+    let next = rsc.widgets().needs_redraw.iter().copied()
+        .filter(|id| !self.deferred.contains(id))
+        .max_by_key(|&id| self.depth(id));
+    let Some(id) = next else { break };
+    if !self.redraw(id, rsc) {
+        self.deferred.insert(id);
+    }
+}
+```
+
+Bryan's, 2026-09-17, and the right answer where `0e0d4af` was a check:
+"then that entire category of issue can't even occur". `dirty_size_under`
+stays in `draw_inner` anyway, because `update` draws the root for a resize
+*before* `redraw_updates` runs at all and the ordering does not cover that
+entry. Whether it is still load-bearing is untested -- the experiment that
+said it was not had a failed edit in it and measured nothing.
+
+Drawn widgets, widget draws and primitive writes are unchanged on every rig
+phase; `many` pays 51 queue pops for 27 and 1059 depth reads for 410.
+
+### Two branches parked, both real, neither ready
+
+**`wip/stack-fraction-twice`.** A stack sized by a child that reports a
+*fraction* applies that fraction twice: its parent places the stack at the
+reported length, and `box_of(size)` then takes the same fraction of that
+box. Half a row becomes a quarter. Pixels are idempotent under a second
+application, so only a share ever shrank -- and warm and cold shrink alike,
+so **no oracle can see it**. Bryan: "I believe this exact thing has come up
+multiple times for some reason."
+
+The fix is that every child gets the whole box, plus `widget_at` not
+resolving a rule into a box already chosen from it. `Painter::box_of` is
+deleted rather than guarded: a first attempt made it answer the whole box on
+a `decided` axis, which fails because `place` can reuse the stack's
+*measuring* drawing by remapping it, so `Stack::draw` never re-runs. **A
+drawing has to be a function of its box alone** -- if `decided` is in it, a
+reused drawing is wrong.
+
+What stops it landing: seed 1091 at depth 4, `shuffle-swap-for-three`,
+disagrees by three steps where the oracle tolerates two (warm 1053.9971
+against cold 1054). `box_of` was also making placement *exact*, by handing a
+child a box of exactly the length it asked for, and the whole box puts a
+rounding back at each nesting level. Find that composition; do not widen
+`AGREE_STEPS`.
+
+**`wip/padding-outset-and-inset`.** Padding goes outside what it pads and
+never insets the child (Bryan, 2026-09-17): otherwise a child's `rel` and
+`leftover` would mean the inner box while its `px` meant the outer one.
+`Padding::region` moves the child's box in rather than shrinking it, a new
+`Inset` widget with `.inset()` is the old behaviour, and `Pad` is to be
+renamed **`Outset`** with `.outset()` to match. `in_parent_frame`'s
+composition and the `reports_of` argument go with it -- a report comes up
+raw and the parent says what it is a fraction of, which `Inset` does for
+itself.
+
+What stops it landing: a child declaring `rel(0.5)` under an `Inset` comes
+out 47.5 px wide of the 190 inside rather than 95, and the second halving is
+unaccounted for. The `Pad` half is green on its own; three tests moved to
+`.inset()` because they were using padding as scaffolding rather than
+testing it.
+
 ### `Span`'s leftover boundary is a third expression for the room
 
 The decision uses a rounded division, `total.px.div(fixed)`, while the room
@@ -477,7 +561,7 @@ above for what closing the rest would cost.
 
 ## Verification at the current head
 
-At `c8beca5`:
+At `a92c6ac`:
 
 - `cargo fmt --all --check`, `cargo clippy --workspace --all-targets --
   -D warnings`, `cargo test --workspace`: green, 90 suite tests, 19 core
@@ -497,7 +581,9 @@ At `c8beca5`:
   width of the widest of them.
 - Twenty-five rig work counters identical on `cold`, `repaint`, `scroll`,
   `resize` and `size` across `0e0d4af`; `many` differs only in reuse
-  attempts.
+  attempts. Across `a92c6ac` drawn widgets, widget draws and primitive
+  writes are identical on every phase, and only the scheduling counters
+  move.
 
 **None of that reaches seeds 1121 and 1839 at depth 4**, which fail on this
 head and on `ea6dbae` alike. Everything below is verification of what was
@@ -668,15 +754,23 @@ The replay used for the reference check:
 
 In order, from the review above and Bryan's steer (2026-09-17):
 
-1. **A fast test for `0e0d4af`**, the stale-answer guard, which went in
+1. **`wip/stack-fraction-twice`**: find the composition that went from
+   exact to rounded when `box_of` stopped narrowing, and land it. This is
+   the one outright wrong layout known on the branch.
+2. **`wip/padding-outset-and-inset`**: account for the second halving under
+   `Inset`, rename `Pad` to `Outset` and `.pad()` to `.outset()`, and audit
+   every `.pad()` in the examples for which of the two it meant.
+3. **A fast test for `0e0d4af`**, the stale-answer guard, which went in
    with only a fuzz seed behind it. The shape wanted is a widget drawing
    while a size dependency two levels under it is dirty, where its
    drawing is reusable at the measuring box and not at the placing one.
-2. Write `ActiveData::answer` in one place.
-3. Keep the `DrawInfo` on `ActiveData`; delete the copied fields and the
+   Check at the same time whether `a92c6ac`'s ordering has made the guard
+   dead outside the resize path.
+4. Write `ActiveData::answer` in one place.
+5. Keep the `DrawInfo` on `ActiveData`; delete the copied fields and the
    reconstruction in `redraw`.
-4. `Span`'s leftover boundary through `Holds::through`.
-5. **Round on the CPU and snap to the nearest pixel in the shader**, as
+6. `Span`'s leftover boundary through `Holds::through`.
+7. **Round on the CPU and snap to the nearest pixel in the shader**, as
    one change with one verification. Bryan approved the snap on 2026-09-17
    (rendering may change wherever it brings the screen closer to what the
    user's code says: three equal sections of 1000 px need one of them
@@ -692,20 +786,20 @@ In order, from the review above and Bryan's steer (2026-09-17):
    bounds move by half a `Rel` step); check with `nm` that `UiSpan::within`
    still inlines; expect a couple of percent of instructions and re-run the
    long fuzzers and the render set once for both.
-6. The smaller items: the stale `f32` comment, the gap of an undrawn child,
+8. The smaller items: the stale `f32` comment, the gap of an undrawn child,
    confirm nested `leftover` weights, one zero-divisor fallback. Add to
    them: a span that overflows itself hands a child a box of negative
    length, which is ordinary now rather than a corner, and nothing states
    what a widget may assume about one.
-7. `LazySpan`, the next LAYOUT.md §2 item. Region nodes cover the movable
+9. `LazySpan`, the next LAYOUT.md §2 item. Region nodes cover the movable
    subtree case; do not restore a separate child-placement API.
-8. `SizeRule::{Min, Max, Clamp}`, restoring the `max_width`/`max_height`
+10. `SizeRule::{Min, Max, Clamp}`, restoring the `max_width`/`max_height`
    builders `8220a78` deleted. The clamp boundary is a hard layout decision
    with an exact `Holds` split at the crossover, both sides in `Px`. Still
    awaiting Bryan: whether a `Max` narrows the box the child draws in, or
    only what the parent reports for it.
-9. `Scroll` taking a direction rather than one axis.
-10. The measure/draw split, once the above is in. It deletes the two-ask
+11. `Scroll` taking a direction rather than one axis.
+12. The measure/draw split, once the above is in. It deletes the two-ask
     protocol, which is what `0e0d4af` had to put a guard around.
 
 `docs/LAYOUT.md` §4, §5 and the density section are stale: they name