feat: enable full backup support for Seedvault

        android:label="@string/app_name"

        android:theme="@style/Theme.K9.Startup"

        android:resizeableActivity="true"

        android:allowBackup="false"

        android:allowBackup="true"

        android:backupAgent="com.fsck.k9.MailBackupAgent"

        android:fullBackupContent="@xml/backup_rules"

        android:dataExtractionRules="@xml/data_extraction_rules"

        android:fullBackupOnly="true"

        android:supportsRtl="true"

        android:hasFragileUserData="false"

        tools:replace="android:theme"

/*

 * Copyright (C) 2026 e Foundation

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * 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 <https://www.gnu.org/licenses/>.

 *

 */

package com.fsck.k9

import android.app.backup.BackupAgent

import android.app.backup.BackupDataInput

import android.app.backup.BackupDataOutput

import android.app.backup.FullBackupDataOutput

import android.os.Build

import android.os.ParcelFileDescriptor

import androidx.annotation.RequiresApi

import java.io.File

import java.io.IOException

import timber.log.Timber

/*

 * Note:

 * - We rely only on full backup.

 * - Backup is allowed only for encrypted or device-to-device transports.

 * - Only selected app data is backed up (databases + shared preferences).

 */

class MailBackupAgent : BackupAgent() {

    override fun onBackup(

        oldState: ParcelFileDescriptor?,

        data: BackupDataOutput?,

        newState: ParcelFileDescriptor?

    ) = Unit

    override fun onRestore(

        data: BackupDataInput?,

        appVersionCode: Int,

        newState: ParcelFileDescriptor?

    ) = Unit

    @RequiresApi(Build.VERSION_CODES.P)

    override fun onFullBackup(data: FullBackupDataOutput) {

        val flags = data.transportFlags

        val allowed = flags and FLAG_CLIENT_SIDE_ENCRYPTION_ENABLED != 0 ||

            flags and FLAG_DEVICE_TO_DEVICE_TRANSFER != 0

        if (!allowed) return

        BACKUP_DIRS.forEach { backupDir(File(dataDir, it), data) }

    }

    private fun backupDir(dir: File, data: FullBackupDataOutput) {

        if (!dir.isDirectory) return

        try {

            dir.listFiles()?.forEach { file ->

                if (file.isDirectory) {

                    backupDir(file, data)

                } else if (shouldBackupFile(file)) {

                    fullBackupFile(file, data)

                }

            }

        } catch (e: SecurityException) {

            Timber.e(e, "Skipping restricted")

        } catch (e: IOException) {

            Timber.e(e, "I/O error during backup")

        }

    }

    private fun shouldBackupFile(file: File) =

        EXCLUDED_SUFFIXES.none(file.name::endsWith)

    companion object {

        private val EXCLUDED_SUFFIXES = listOf("-journal", "-shm", "-wal")

        private val BACKUP_DIRS = listOf(

            "databases",

            "shared_prefs"

        )

    }

}

<?xml version="1.0" encoding="utf-8"?>

<!--

  ~ Copyright (C) 2026 e Foundation

  ~

  ~ This program is free software: you can redistribute it and/or modify

  ~ it under the terms of the GNU General Public License as published by

  ~ the Free Software Foundation, either version 3 of the License, or

  ~ (at your option) any later version.

  ~

  ~ 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 <https://www.gnu.org/licenses/>.

-->

<full-backup-content>

    <include domain="sharedpref" path="." />

    <include domain="database" path="." />

    <exclude domain="database" path="preferences_storage-journal" />

    <exclude domain="database" path="preferences_storage-shm" />

    <exclude domain="database" path="preferences_storage-wal" />

</full-backup-content>

<?xml version="1.0" encoding="utf-8"?>

<!--

  ~ Copyright (C) 2026 e Foundation

  ~

  ~ This program is free software: you can redistribute it and/or modify

  ~ it under the terms of the GNU General Public License as published by

  ~ the Free Software Foundation, either version 3 of the License, or

  ~ (at your option) any later version.

  ~

  ~ 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 <https://www.gnu.org/licenses/>.

  -->

<data-extraction-rules>

    <cloud-backup disableIfNoEncryptionCapabilities="true">

        <include domain="sharedpref" path="." />

        <include domain="database" path="." />

        <exclude domain="database" path="preferences_storage-journal" />

        <exclude domain="database" path="preferences_storage-shm" />

        <exclude domain="database" path="preferences_storage-wal" />

    </cloud-backup>

    <device-transfer>

        <include domain="sharedpref" path="." />

        <include domain="database" path="." />

        <exclude domain="database" path="preferences_storage-journal" />

        <exclude domain="database" path="preferences_storage-shm" />

        <exclude domain="database" path="preferences_storage-wal" />

    </device-transfer>

</data-extraction-rules>