diff --git a/src/uix/morfo/components/button.ts b/src/uix/morfo/components/button.ts
index 76433753c..cb428a031 100644
--- a/src/uix/morfo/components/button.ts
+++ b/src/uix/morfo/components/button.ts
@@ -81,13 +81,23 @@ export const buttonMorfo = {
 			kind: 'public',
 			defaultElement: 'button',
 			optional: false,
+			// Button's loading state is fully expressed by the `data-loading`
+			// presence flag (declared below) — eidos CSS already uses
+			// `[data-loading]`, NOT `[data-state='loading']`. The morfo
+			// previously declared a redundant `data-state ∈ [idle, loading]`
+			// enum that:
+			//   (a) duplicated `data-loading`
+			//   (b) emitted `data-state="idle"` on every non-loading button,
+			//       which CLOBBERED the host disclosure's `data-state="open|closed"`
+			//       whenever Button was used as the chrome for a
+			//       RowDetailTrigger / ExpandTrigger / DropdownMenu Trigger
+			//       (audit 2026-05-27 caught this).
+			// `data-state` removed entirely. The book doctrine favours
+			// "presence = active state, absence = rest" for binary states
+			// (data-disabled, data-loading). 'idle' is not a value — it's
+			// the natural rest where no flag is emitted.
 			states: ['idle', 'loading'],
 			data: [
-				{
-					attr: 'data-state',
-					values: ['idle', 'loading'],
-					value: v.stateRef('loading')
-				},
 				{
 					/**
 					 * Resolved visual color. Per doctrine, when intent is