The contract test suite's per-element binding-shape check treated
EVERY element's onclick as a plain Action, and its interactive-element
set (used both for "declares a real handler" and "has an accessible
tooltip") had no entry for <column> at all — both would misvalidate a
future mosstank.xml <column> the way Campaign VT slice 1 Part B and
this fix round's item 1 actually shipped it (onchange/onclick as
Action<int>, the row index).
Extracted the per-element dispatch out of
EveryInteractiveBindingMatchesTheRetainedUiDelegateShape into
AssertElementBindingsMatchRetainedUiDelegateShape, which now
special-cases "column": both onchange and onclick must resolve to
Action<int>, never plain Action. The interactive-element name list is
now the single shared InteractiveElementNames array (was duplicated
inline in EveryInteractiveControlDeclaresARealHandlerBinding and
TextlessAndAbbreviatedControlsHaveAccessibleRetailTooltips), with
"column" added — zero behavior change against mosstank.xml today (it
has no <column> elements yet), confirmed by the existing 190-control
count assertion staying green.
New tests: InteractiveElementNames_IncludesColumn pins the addition
directly; Column_OnchangeAndOnclick_MustBeActionOfInt builds a
synthetic <column> (not loaded from mosstank.xml, which has none) and
proves both a correctly-typed Action<int> onchange passes and a
column onclick bound to a plain Action (the shape every OTHER
element's onclick uses) is rejected — confirmed by temporarily
removing the "column" special case and rerunning: the plain-Action
onclick then passed silently ("No exception was thrown", the
generic Action check being satisfied by a real Action property),
proving the test only passes because the fix's column-specific
Action<int> enforcement is present.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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