soma/morfo: fix conditional attr cleanup in resolvePartAttrs

Real bug surfaced by user testing the Toggle pilot: setting `invalid` to true
emitted `data-invalid` and `aria-invalid` correctly, but flipping it back to
false left the attrs on the DOM. The red border from CSS based on
`[data-invalid]` stayed lit.

Cause: `resolvePartAttrs` skipped declared attrs whose condition was falsy.
The map handed to `dom.apply` lacked the key, so dom.apply (which only
iterates the keys it receives) had no instruction to remove the attr from
the previous tick.

The function's JSDoc claimed it emitted `undefined` for non-matching attrs.
The implementation didn't match. Now it does:

- Conditional attrs with falsy condition are emitted as `undefined` →
  `dom.apply` removes them from the DOM and Svelte ignores them at render.
- Data entries without a `value` source are still skipped entirely (they
  are documentation in the morfo, not runtime-managed attrs).

Same fix covers all conditional attrs: data-disabled, data-readonly,
data-required, data-invalid, aria-disabled, aria-readonly, aria-required,
aria-invalid, aria-label — all toggled on/off cleanly now.

Regression test added covering the invalid true→false→true cycle.

Verification: 5/5 runtime tests, 76/76 focused suite, 66/66 morfo-check,
68/68 smoke.

src/uix/soma/morfo/resolver.ts

@@ -107,9 +107,17 @@ export function resolveMorfoAriaValue(entry: MorfoAriaEntry, bindings: MorfoBind
 
 /**
  * Resolves a part's full attribute map (role + data-* + aria-*) against the
- * given bindings. Returns `undefined`-valued entries for declared attrs that
- * shouldn't be emitted in the current state — the caller decides whether to
- * skip them (Svelte does it automatically; `dom.apply` removes them).
+ * given bindings.
+ *
+ * The map ALWAYS includes every declared attr (data with a `value` source +
+ * every aria entry). Attrs whose condition is falsy or whose value source
+ * resolves to nothing are emitted as `undefined`, which `dom.apply` reads as
+ * "remove this attribute" and Svelte ignores during render. This is what
+ * lets the runtime clean up attrs that previously matched their condition
+ * but no longer do (e.g. `data-invalid` toggling from set to absent).
+ *
+ * Entries with no `value` source on `data` are skipped entirely — they are
+ * documentation in the morfo, not runtime-managed attrs.
  */
 export function resolvePartAttrs(
 	partMeta: MorfoPart,
@@ -123,19 +131,19 @@ export function resolvePartAttrs(
 
 	for (const data of partMeta.data) {
 		if (!data.value) continue;
-		if (!shouldEmitMorfoEntry(data.condition, bindings)) continue;
-		const value = resolveMorfoDataValue(data, bindings);
-		if (value !== undefined) {
-			result[data.attr] = value;
+		if (!shouldEmitMorfoEntry(data.condition, bindings)) {
+			result[data.attr] = undefined;
+			continue;
 		}
+		result[data.attr] = resolveMorfoDataValue(data, bindings);
 	}
 
 	for (const aria of partMeta.aria) {
-		if (!shouldEmitMorfoEntry(aria.condition, bindings)) continue;
-		const value = resolveMorfoAriaValue(aria, bindings);
-		if (value !== undefined) {
-			result[aria.attr] = value;
+		if (!shouldEmitMorfoEntry(aria.condition, bindings)) {
+			result[aria.attr] = undefined;
+			continue;
 		}
+		result[aria.attr] = resolveMorfoAriaValue(aria, bindings);
 	}
 
 	return result;

src/uix/soma/morfo/runtime.svelte.test.ts

@@ -125,6 +125,42 @@ describe('createMorfoRuntime', () => {
 		cleanup()
 	})
 
+	it('removes conditional attrs when their condition flips back to false', () => {
+		const ref = state<HTMLElement | null>(null)
+		const invalid = state(false)
+		const { cleanup } = withEffectRoot(() => {
+			const id = state('tog-1')
+			const r = createMorfoRuntime(toggleMorfo, {
+				dom,
+				states: { on: () => false },
+				props: {
+					disabled: () => false,
+					readonly: () => false,
+					required: () => false,
+					invalid: () => invalid.current,
+					ariaLabel: () => undefined
+				}
+			})
+			r.registerPart('provider', { id, ref })
+		})
+
+		ref.current = target
+		flushSync()
+		expect(target.hasAttribute('data-invalid')).toBe(false)
+		expect(target.hasAttribute('aria-invalid')).toBe(false)
+
+		invalid.current = true
+		flushSync()
+		expect(target.getAttribute('data-invalid')).toBe('')
+		expect(target.getAttribute('aria-invalid')).toBe('true')
+
+		invalid.current = false
+		flushSync()
+		expect(target.hasAttribute('data-invalid')).toBe(false)
+		expect(target.hasAttribute('aria-invalid')).toBe(false)
+		cleanup()
+	})
+
 	it('throws when registering an unknown part', () => {
 		const { cleanup } = withEffectRoot(() => {
 			const r = createMorfoRuntime(toggleMorfo, { dom })