Fix conflict notification IDs for large file IDs

opencloudApp/src/main/java/eu/opencloud/android/utils/NotificationUtils.kt

@@ -179,12 +179,26 @@ object NotificationUtils {
                 showConflictActivityIntent, pendingIntentFlags
             )
         )
-        var notificationId = 0
-
         // We need a notification id for each file in conflict, let's use the file id but in a safe way
-        if (fileInConflict.id!!.toInt() >= Int.MIN_VALUE && fileInConflict.id!!.toInt() <= Int.MAX_VALUE) {
-            notificationId = fileInConflict.id!!.toInt()
-        }
+        val notificationId = getConflictNotificationId(fileInConflict)
         notificationManager.notify(notificationId, notificationBuilder.build())
     }
+
+    internal fun getConflictNotificationId(fileInConflict: OCFile): Int {
+        val fileId = fileInConflict.id
+        return if (fileId != null && fileId in Int.MIN_VALUE.toLong()..Int.MAX_VALUE.toLong()) {
+            fileId.toInt()
+        } else {
+            stableConflictNotificationFallback(fileInConflict, fileId)
+        }
+    }
+
+    private fun stableConflictNotificationFallback(fileInConflict: OCFile, fileId: Long?): Int =
+        listOf(
+            fileId?.toString().orEmpty(),
+            fileInConflict.owner,
+            fileInConflict.spaceId.orEmpty(),
+            fileInConflict.remoteId.orEmpty(),
+            fileInConflict.remotePath,
+        ).joinToString(separator = "|").hashCode()
 }

opencloudApp/src/test/java/eu/opencloud/android/utils/NotificationUtilsTest.kt

@@ -0,0 +1,67 @@
+/**
+ * openCloud Android client application
+ *
+ * Copyright (C) 2026 openCloud GmbH.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package eu.opencloud.android.utils
+
+import eu.opencloud.android.domain.files.model.OCFile
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNotEquals
+import org.junit.Test
+
+class NotificationUtilsTest {
+
+    @Test
+    fun conflictNotificationIdUsesIntRangeFileId() {
+        val file = conflictFile(id = 42L)
+
+        assertEquals(42, NotificationUtils.getConflictNotificationId(file))
+    }
+
+    @Test
+    fun conflictNotificationIdUsesStableFallbackForLargeFileId() {
+        val file = conflictFile(id = Long.MAX_VALUE)
+
+        val notificationId = NotificationUtils.getConflictNotificationId(file)
+
+        assertNotEquals(Long.MAX_VALUE.toInt(), notificationId)
+        assertEquals(notificationId, NotificationUtils.getConflictNotificationId(file.copy()))
+    }
+
+    @Test
+    fun conflictNotificationIdUsesStableFallbackForMissingFileId() {
+        val file = conflictFile(id = null)
+
+        val notificationId = NotificationUtils.getConflictNotificationId(file)
+
+        assertEquals(notificationId, NotificationUtils.getConflictNotificationId(file.copy()))
+        assertNotEquals(
+            notificationId,
+            NotificationUtils.getConflictNotificationId(file.copy(remotePath = "/Documents/other.txt"))
+        )
+    }
+
+    private fun conflictFile(id: Long?) = OCFile(
+        id = id,
+        owner = "user@example.org",
+        remotePath = "/Documents/conflict.txt",
+        remoteId = "remote-file-id",
+        length = 1L,
+        modificationTimestamp = 1L,
+        mimeType = "text/plain",
+        spaceId = "space-id",
+    )
+}