Replace the step 3 plan with the one-ask protocol and record why it failed

The handoff now describes wip/one-ask at 3091fb8: a widget draws once in
the box it is asked in, its answer is placed by re-expressing the drawing,
and nothing is drawn again in a box an answer chose. The log records what
the step 3 plan got wrong -- it kept the second draw whose measurement
bit could not be defined, demanded a contract of the answer box, and
narrowed frames by region -- and what fuzzing the new protocol found: the
Part::Of composition dropping a pinned length, and a local redraw that
must be put back in the parent's answer box. The Pad frame rule is left
as a decision for Bryan with its cost stated.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

docs/LAYOUT.md

@@ -326,11 +326,15 @@ inside that area, and reports the child's used size plus padding. A
 share less that padding. The mixed "outset pixels, inset fractions and
 shares" interpretation is rejected.
 
-The current experiment still redraws some widgets in boxes derived from their
-own answers. That is the open protocol defect, not a design invariant. The
-target in `docs/HANDOFF.md` evaluates container bodies only in boxes a parent
-offered or decided; placing an answer reuses or translates its drawing rather
-than running the body in an answer-derived box.
+A widget draws once, in the box it is asked in; its answer is placed inside
+that box by re-expressing the drawing, and nothing is drawn again in a box an
+answer chose. `Holds` is a contract about the ask box alone, read only to
+decide whether a re-ask can be skipped. A container that puts an answer
+somewhere other than where it asked says so with `Painter::place_at`, which
+never runs the body. A frame is narrowed by a length of the parent's frame,
+never by a region, and is put back into the part by the child's alignment on
+every placement. This is `wip/one-ask` in the experiment checkout; whether
+`Pad` narrows the frame by its padding is still open in `docs/HANDOFF.md`.
 
 ## Layout decisions and invariants (2026-09-15 to 2026-09-17)