From 0b93cf858c2293e79fae98d43314d85e5726e176 Mon Sep 17 00:00:00 2001
From: Marcos Caceres <caceres_m@apple.com>
Date: Fri, 17 Oct 2025 14:45:43 +0800
Subject: [PATCH] Add hidden document monitoring in parallel orientation lock
 steps

The 'apply orientation lock' algorithm monitors if documents stop being
fully active during parallel execution, but was missing equivalent
monitoring for document visibility state changes.

This creates inconsistency where:
- Common safety checks prevent hidden documents from starting locks
- Parallel steps monitor fully-active state changes
- But parallel steps don't monitor hidden state changes

This fix adds monitoring for documents becoming hidden during parallel
orientation lock processing, with consistent AbortError rejection.

Fixes #256
---
 index.html | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/index.html b/index.html
index 5b5f19c..ed4a6e9 100644
--- a/index.html
+++ b/index.html
@@ -694,6 +694,11 @@ <h2>
             not `null`, [=reject and nullify the current lock promise=] of
             |document| with an {{"AbortError"}} and abort these steps.
             </li>
+            <li>If |document|'s [=Document/visibility state=] becomes "hidden", and
+            if the |document|'s {{Document/[[orientationPendingPromise]]}} is
+            not `null`, [=reject and nullify the current lock promise=] of
+            |document| with an {{"AbortError"}} and abort these steps.
+            </li>
             <li>If |orientation| is `null`, [=unlock the screen orientation=].
             </li>
             <li>Otherwise, attempt to [=lock the screen orientation=] to