fix(a11y): drop assertionFailure for multiple Receivers in deferral container

BlueprintUIAccessibilityCore/Sources/AccessibilityDeferral.swift

@@ -226,8 +226,11 @@ extension AccessibilityDeferral {
             sources.forEach { $0.accessibilityElementsHidden = false }
 
 
+            // During a reentrant Blueprint update (e.g. a forced layoutBelowIfNeeded mid-update),
+            // this container can transiently observe both the outgoing and incoming Receiver before
+            // the hierarchy settles. That isn't a misconfiguration, so we recover and bail; the
+            // settled layout pass re-runs updateAccessibility() with the single surviving Receiver.
             guard receivers.count <= 1 else {
-                assertionFailure("AccessibilityDeferral.ParentContainer must contain at most one Receiver; found \(receivers.count).")
                 receivers.forEach { $0.apply(content: nil, frameProvider: nil) }
                 return
             }

CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- `AccessibilityDeferral` no longer aborts debug builds when its container transiently observes more than one `Receiver`. The `assertionFailure` treated more than one `Receiver` as a misconfiguration, but that state became reachable once `BlueprintView` began deferring reentrant updates (#618) instead of crashing on them: a reentrant layout pass can now run while the hierarchy is mid-swap, with the outgoing and incoming `Receiver` both briefly present. Previously that reentrancy tripped `BlueprintView`'s precondition first, so the deferral container never reached this state. The assertion was removed in favor of the existing safe recovery (clearing receiver content and bailing); the settled layout pass re-applies content with the single surviving `Receiver`.
+
 ### Added
 
 ### Removed