From 35d2d5f677939f2ebfea9448a3852e1bf822b528 Mon Sep 17 00:00:00 2001
From: xhon-pelushi <xhon@pelushi.com>
Date: Thu, 13 Aug 2026 09:57:33 -0400
Subject: [PATCH] Debounce details screen navigation to prevent crash

Rapidly tapping a package list item (e.g. a dependency shown on the
details screen itself) queued fragment transactions faster than their
postponed enter transitions could finish, leaving FragmentManager in
an inconsistent state and crashing with:

  IllegalStateException: Fragment DetailsScreen{...} did not return a
  View from onCreateView() or this was called before onCreateView().

Ignore repeated navigation to the details screen within 500ms of the
previous one so only one transition is ever in flight.

Fixes #436
---
 .../app/grapheneos/apps/ui/PackageListAdapter.kt   | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/app/src/main/java/app/grapheneos/apps/ui/PackageListAdapter.kt b/app/src/main/java/app/grapheneos/apps/ui/PackageListAdapter.kt
index 357155071..24f395784 100644
--- a/app/src/main/java/app/grapheneos/apps/ui/PackageListAdapter.kt
+++ b/app/src/main/java/app/grapheneos/apps/ui/PackageListAdapter.kt
@@ -1,6 +1,7 @@
 package app.grapheneos.apps.ui
 
 import android.annotation.SuppressLint
+import android.os.SystemClock
 import android.view.ViewGroup
 import androidx.core.view.ViewCompat
 import androidx.core.view.WindowInsetsCompat
@@ -112,8 +113,21 @@ fun PackageListItemBinding.set(fragment: Fragment, pkgState: PackageState) {
     root.tag = pkgState
 }
 
+// Debounces navigation to the details screen: without this, tapping a list item (e.g. a
+// dependency shown within the details screen itself) repeatedly in quick succession queues up
+// fragment transactions faster than their enter transitions can finish, which can crash
+// FragmentManager (see https://github.com/GrapheneOS/AppStore/issues/436).
+private const val DETAILS_NAVIGATION_DEBOUNCE_MS = 500L
+private var lastDetailsNavigationTime = 0L
+
 fun PackageListItemBinding.setOnClickListener(fragment: Fragment) {
     root.setOnClickListener { root ->
+        val now = SystemClock.elapsedRealtime()
+        if (now - lastDetailsNavigationTime < DETAILS_NAVIGATION_DEBOUNCE_MS) {
+            return@setOnClickListener
+        }
+        lastDetailsNavigationTime = now
+
         val packageState = root.tag as PackageState
         val pkgName = packageState.pkgName
         fragment.findNavController().navigate(NavGraphDirections.actionToDetailsScreen(pkgName))