Add flag for fixing Avalanche HUN replacement when critical HUN arrives

The existing behavior: FSI and Remote Input activated HUNs are never
replaced by another HUN.
Behavior wanted: any HUN can be replaced by critical HUNs (FSI and
incoming calls)

Bug: 403301297
Test: Manual, TheFlippinApp
Flag: com.android.systemui.avalanche_replace_hun_when_critical
Change-Id: I91b3bed755f395d944a584ca98ada91816475f2b

2 files changed, 63 insertions, 0 deletions

diff --git a/packages/SystemUI/aconfig/systemui.aconfig b/packages/SystemUI/aconfig/systemui.aconfig
index cea91a18ae32..58c0185491eb 100644
--- a/packages/SystemUI/aconfig/systemui.aconfig
+++ b/packages/SystemUI/aconfig/systemui.aconfig
@@ -573,6 +573,16 @@ flag {
 }
 
 flag {
+   name: "avalanche_replace_hun_when_critical"
+   namespace: "systemui"
+   description: "Fix for replacing a sticky HUN when a critical HUN posted"
+   bug: "403301297"
+   metadata {
+       purpose: PURPOSE_BUGFIX
+   }
+}
+
+flag {
     name: "indication_text_a11y_fix"
     namespace: "systemui"
     description: "add double shadow to the indication text at the bottom of the lock screen"
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/shared/AvalancheReplaceHunWhenCritical.kt b/packages/SystemUI/src/com/android/systemui/statusbar/notification/shared/AvalancheReplaceHunWhenCritical.kt
new file mode 100644
index 000000000000..0ccd6064d9a3
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/shared/AvalancheReplaceHunWhenCritical.kt
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2025 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.systemui.statusbar.notification.shared
+
+import com.android.systemui.Flags
+import com.android.systemui.flags.FlagToken
+import com.android.systemui.flags.RefactorFlagUtils
+
+/** Helper for reading or using the avalanche replace Hun when critical flag state. */
+@Suppress("NOTHING_TO_INLINE")
+object AvalancheReplaceHunWhenCritical {
+    /** The aconfig flag name */
+    const val FLAG_NAME = Flags.FLAG_AVALANCHE_REPLACE_HUN_WHEN_CRITICAL
+
+    /** A token used for dependency declaration */
+    val token: FlagToken
+        get() = FlagToken(FLAG_NAME, isEnabled)
+
+    /** Is the refactor enabled */
+    @JvmStatic
+    inline val isEnabled
+        get() = Flags.avalancheReplaceHunWhenCritical()
+
+    /**
+     * Called to ensure code is only run when the flag is enabled. This protects users from the
+     * unintended behaviors caused by accidentally running new logic, while also crashing on an eng
+     * build to ensure that the refactor author catches issues in testing.
+     */
+    @JvmStatic
+    inline fun isUnexpectedlyInLegacyMode() =
+        RefactorFlagUtils.isUnexpectedlyInLegacyMode(isEnabled, FLAG_NAME)
+
+    /**
+     * Called to ensure code is only run when the flag is disabled. This will throw an exception if
+     * the flag is enabled to ensure that the refactor author catches issues in testing.
+     */
+    @JvmStatic
+    inline fun assertInLegacyMode() = RefactorFlagUtils.assertInLegacyMode(isEnabled, FLAG_NAME)
+}