Keep standalone initramfs for grub-btrfs when UKI is enabled (#4513)

* Keep standalone initramfs for grub-btrfs when UKI is enabled

Fixes #4505

* Move keep_initramfs logic into add_bootloader()

The grub-btrfs snapshot detection was in guided.py, forcing custom
script authors to replicate it. Since Installer already holds
disk_config, the check belongs inside add_bootloader().

archinstall/lib/installer.py

@@ -1754,6 +1754,7 @@ class Installer:
 		self,
 		root: PartitionModification | LvmVolume,
 		efi_partition: PartitionModification | None,
+		keep_initramfs: bool = False,
 	) -> None:
 		if not efi_partition or not efi_partition.mountpoint:
 			raise ValueError(f'Could not detect ESP at mountpoint {self.target}')
@@ -1777,11 +1778,11 @@ class Installer:
 			config = preset.read_text().splitlines(True)
 
 			for index, line in enumerate(config):
-				# Avoid storing redundant image file
 				if m := image_re.match(line):
-					image = self.target / m.group(2)
-					image.unlink(missing_ok=True)
-					config[index] = '#' + m.group(1)
+					if not keep_initramfs:
+						image = self.target / m.group(2)
+						image.unlink(missing_ok=True)
+						config[index] = '#' + m.group(1)
 				elif m := uki_re.match(line):
 					if diff_mountpoint:
 						config[index] = m.group(2) + diff_mountpoint + m.group(3)
@@ -1800,7 +1801,12 @@ class Installer:
 		if not self.mkinitcpio(['-P']):
 			error('Error generating initramfs (continuing anyway)')
 
-	def add_bootloader(self, bootloader: Bootloader, uki_enabled: bool = False, bootloader_removable: bool = False) -> None:
+	def add_bootloader(
+		self,
+		bootloader: Bootloader,
+		uki_enabled: bool = False,
+		bootloader_removable: bool = False,
+	) -> None:
 		"""
 		Adds a bootloader to the installation instance.
 		Archinstall supports one of five types:
@@ -1849,7 +1855,13 @@ class Installer:
 				bootloader_removable = False
 
 		if uki_enabled:
-			self._config_uki(root, efi_partition)
+			keep_initramfs = (
+				bootloader == Bootloader.Grub
+				and self._disk_config.has_default_btrfs_vols()
+				and self._disk_config.btrfs_options is not None
+				and self._disk_config.btrfs_options.snapshot_config is not None
+			)
+			self._config_uki(root, efi_partition, keep_initramfs)
 
 		match bootloader:
 			case Bootloader.Systemd:

archinstall/scripts/guided.py

@@ -115,7 +115,11 @@ def perform_installation(
 			installation.setup_swap(algo=config.swap.algorithm)
 
 		if config.bootloader_config and config.bootloader_config.bootloader != Bootloader.NO_BOOTLOADER:
-			installation.add_bootloader(config.bootloader_config.bootloader, config.bootloader_config.uki, config.bootloader_config.removable)
+			installation.add_bootloader(
+				config.bootloader_config.bootloader,
+				config.bootloader_config.uki,
+				config.bootloader_config.removable,
+			)
 
 		if config.network_config:
 			install_network_config(