feat(bootloader): add grub-btrfs snapshot boot support

Co-authored-by: Junie <junie@jetbrains.com>

AGENTS.md

@@ -141,6 +141,7 @@ Dieses Repository ist ein modulares, automatisiertes Setup- und Konfigurations-F
 - `ensure_timeshift_btrfs_config`: Erstellt bzw. initialisiert die Timeshift-Btrfs-Konfiguration (`/etc/timeshift/timeshift.json`, automatische Boot-Snapshots, Retention auf 5 Snapshots) für die Root-UUID.
 - `ensure_timeshift_boot_service`: Richtet den `timeshift-boot.service` und Cron-Einträge für automatische Boot-Snapshots ein.
 - `ensure_timeshift_apt_hook`: Richtet einen DPkg/APT-Hook (`/etc/apt/apt.conf.d/80timeshift-auto-snapshot` und `/usr/local/bin/timeshift-apt-hook`) für automatische Snapshots vor System-Updates ein.
+- `ensure_grub_btrfs`: Installiert und konfiguriert `grub-btrfs` sowie den `grub-btrfsd`-Dienst für die automatische Generierung von Snapshot-Bootmenüeinträgen in GRUB.
 - `create_timeshift_snapshot "comment" [tags]`: Erstellt einen Timeshift-Btrfs-Snapshot an kritischen Setup-Meilensteinen (idempotent, steuerbar über `ENABLE_TIMESHIFT_SNAPSHOTS` in `config/setup.conf`).
 
 ### `lib/tui.sh`

README.md

@@ -110,6 +110,7 @@ sudo ./setup.sh --stages 04,05
    - Alle Phasen können beliebig oft wiederholt werden.
    - Vorhandene Dotfiles (`~/.zshrc`) und Konfigurationen (`/etc/default/grub`) werden vor Änderungen automatisch mit Zeitstempel (`.backup_YYYYMMDD_HHMMSS`) gesichert.
    - Auf Btrfs-Systemen werden mit Timeshift automatisch Rollback-Punkte vor und nach kritischen Operationen (Dist-Upgrade, Kernel-Installation, Paketinstallation, Desktop-Setup), bei jedem System-Update (automatischer APT/DPkg-Pre-Invoke-Hook) sowie bei jedem Systemstart (`timeshift-boot.service`) erstellt, wobei standardmäßig die letzten 5 Snapshots vorgehalten werden.
+   - Mittels `grub-btrfs` und dem Hintergrunddienst `grub-btrfsd` werden Btrfs-Snapshots automatisch in das GRUB-Bootmenü integriert, sodass direkt beim Systemstart in beliebige Snapshots gebootet werden kann.
 4. **Debian Unstable Absicherung**:
    - Moderne Deb822-Quellen und dedizierte Keyrings in `/etc/apt/keyrings/`.
    - Installation von `apt-listbugs` und `apt-listchanges` vor dem `dist-upgrade` schützt vor bekannten kritischen Paketproblemen.

config/packages/01-base.list

@@ -49,6 +49,7 @@ gparted
 htop
 hunspell
 hunspell-de-de-frami
+inotify-tools
 irqbalance
 keepassxc
 lsd

config/setup.conf

@@ -12,12 +12,13 @@ ENABLE_TIMESHIFT_SNAPSHOTS=1
 TIMESHIFT_COUNT_BOOT=5
 TIMESHIFT_SCHEDULE_BOOT="true"
 TIMESHIFT_SNAPSHOT_ON_UPDATE="true"
+ENABLE_GRUB_BTRFS=1
 
 # Bootloader & Appearance
 GRUB_THEME="vimix"
 PLYMOUTH_THEME="solar"
-GRUB_TIMEOUT=0
+GRUB_TIMEOUT=5
-GRUB_TIMEOUT_STYLE="hidden"
+GRUB_TIMEOUT_STYLE="menu"
 
 # Shell & Userland
 DEFAULT_SHELL="zsh"

lib/btrfs.sh

@@ -467,6 +467,106 @@ EOF
 
     ensure_timeshift_boot_service
     ensure_timeshift_apt_hook
+    ensure_grub_btrfs
+}
+
+# Ensure grub-btrfs is installed and configured to generate GRUB snapshot boot entries
+ensure_grub_btrfs() {
+    local root_prefix="${ROOT_PREFIX:-}"
+    local enable_grub_btrfs="${ENABLE_GRUB_BTRFS:-1}"
+
+    # Check if disabled in configuration
+    if [[ "$enable_grub_btrfs" != "1" && "$enable_grub_btrfs" != "true" ]]; then
+        log_info "GRUB Btrfs snapshot booting disabled in configuration."
+        return 0
+    fi
+
+    # Dry-run check
+    if [[ "${FLAG_DRY_RUN:-0}" -eq 1 ]]; then
+        log_info "[DRY-RUN] Would install and configure grub-btrfs for GRUB snapshot booting."
+        return 0
+    fi
+
+    # Check if root is on Btrfs
+    if ! is_root_btrfs; then
+        log_info "Root filesystem is not Btrfs. Skipping grub-btrfs setup."
+        return 0
+    fi
+
+    log_info "Configuring GRUB Btrfs snapshot support (grub-btrfs)..."
+
+    # Ensure required dependencies are installed
+    if ! command_exists inotifywait || ! command_exists git || ! command_exists make; then
+        log_info "Installing dependencies for grub-btrfs (inotify-tools, git, make)..."
+        DEBIAN_FRONTEND=noninteractive apt-get update -y >/dev/null 2>&1 || true
+        DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends inotify-tools git make 2>/dev/null || true
+    fi
+
+    local repo_dir="${root_prefix}/usr/share/debian-gaming/grub/grub-btrfs"
+    mkdir -p "$(dirname "$repo_dir")"
+
+    if [[ ! -d "$repo_dir/.git" ]]; then
+        log_info "Cloning grub-btrfs repository..."
+        if ! git clone --depth 1 https://github.com/Antynea/grub-btrfs.git "$repo_dir" 2>/dev/null; then
+            log_warn "Failed to clone grub-btrfs repository. Snapshot boot menu may not be available."
+            return 0
+        fi
+    else
+        log_info "grub-btrfs repository already cloned; pulling latest updates..."
+        (cd "$repo_dir" && git pull 2>/dev/null) || log_warn "grub-btrfs git pull skipped."
+    fi
+
+    # Install grub.d script
+    mkdir -p "${root_prefix}/etc/grub.d"
+    if [[ -f "$repo_dir/41_snapshots-btrfs" ]]; then
+        cp -f "$repo_dir/41_snapshots-btrfs" "${root_prefix}/etc/grub.d/41_snapshots-btrfs"
+        chmod 755 "${root_prefix}/etc/grub.d/41_snapshots-btrfs"
+    fi
+
+    # Install default config
+    mkdir -p "${root_prefix}/etc/default/grub-btrfs"
+    if [[ -f "$repo_dir/config" && ! -f "${root_prefix}/etc/default/grub-btrfs/config" ]]; then
+        cp -f "$repo_dir/config" "${root_prefix}/etc/default/grub-btrfs/config"
+        chmod 644 "${root_prefix}/etc/default/grub-btrfs/config"
+    fi
+
+    # Install grub-btrfsd binary
+    mkdir -p "${root_prefix}/usr/bin"
+    if [[ -f "$repo_dir/grub-btrfsd" ]]; then
+        cp -f "$repo_dir/grub-btrfsd" "${root_prefix}/usr/bin/grub-btrfsd"
+        chmod 755 "${root_prefix}/usr/bin/grub-btrfsd"
+    fi
+
+    # Install and configure systemd service for automatic snapshot tracking with Timeshift
+    mkdir -p "${root_prefix}/etc/systemd/system"
+    local service_file="${root_prefix}/etc/systemd/system/grub-btrfsd.service"
+    cat > "$service_file" <<'EOF'
+[Unit]
+Description=Regenerate grub-btrfs.cfg on snapshot changes
+After=local-fs.target
+ConditionPathExists=/etc/default/grub-btrfs/config
+
+[Service]
+Type=simple
+LogLevelMax=notice
+Environment="PATH=/sbin:/bin:/usr/sbin:/usr/bin"
+EnvironmentFile=-/etc/default/grub-btrfs/config
+ExecStart=/usr/bin/grub-btrfsd --syslog --timeshift-auto
+Restart=on-failure
+RestartSec=5s
+
+[Install]
+WantedBy=multi-user.target
+EOF
+    chmod 644 "$service_file"
+
+    if [[ -z "$root_prefix" ]] && command_exists systemctl; then
+        systemctl daemon-reload 2>/dev/null || true
+        systemctl enable grub-btrfsd.service 2>/dev/null || true
+        systemctl restart grub-btrfsd.service 2>/dev/null || true
+    fi
+
+    log_success "grub-btrfs installed and configured successfully."
 }
 
 # Create a Btrfs snapshot using Timeshift

stages/03-bootloader.sh

@@ -7,6 +7,7 @@ set -euo pipefail
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
 source "$SCRIPT_DIR/lib/utils.sh"
+source "$SCRIPT_DIR/lib/btrfs.sh"
 
 if [[ -f "$SCRIPT_DIR/config/setup.conf" ]]; then
     # shellcheck source=/dev/null
@@ -20,8 +21,8 @@ log_step "Running Stage 03: Bootloader & Splash Screen Configuration"
 require_root
 
 GRUB_CFG="/etc/default/grub"
-GRUB_TIMEOUT="${GRUB_TIMEOUT:-0}"
+GRUB_TIMEOUT="${GRUB_TIMEOUT:-5}"
-GRUB_TIMEOUT_STYLE="${GRUB_TIMEOUT_STYLE:-hidden}"
+GRUB_TIMEOUT_STYLE="${GRUB_TIMEOUT_STYLE:-menu}"
 GRUB_CMDLINE_LINUX_DEFAULT_BASE="quiet splash apparmor=1 usbcore.autosuspend=-1 vt.global_cursor_default=0 loglevel=3 rd.luks.options=discard plymouth.ignore-serial-consoles threadirqs"
 GRUB_CMDLINE_LINUX="rcutree.rcu_idle_gp_delay=1"
 GRUB_THEME_DIR="/usr/share/debian-gaming/grub/grub2-themes"
@@ -100,7 +101,16 @@ else
     (cd "$GRUB_THEME_DIR" && git pull 2>/dev/null && ./install.sh -b -t "${GRUB_THEME:-vimix}" 2>/dev/null) || log_warn "Vimix theme update skipped."
 fi
 
-# 5. Update GRUB & Initramfs
+# 5. Configure GRUB Btrfs Snapshot Booting (grub-btrfs)
+log_substep "Configuring GRUB Btrfs snapshot booting support..."
+if is_root_btrfs; then
+    ensure_grub_btrfs
+    log_success "GRUB Btrfs snapshot booting configured."
+else
+    log_info "Root filesystem is not Btrfs. Skipping grub-btrfs setup."
+fi
+
+# 6. Update GRUB & Initramfs
 log_substep "Running update-grub and update-initramfs..."
 if command_exists update-grub; then
     update-grub

stages/06-services.sh

@@ -136,13 +136,15 @@ if command_exists systemctl; then
     log_success "Ollama systemd service configured and enabled."
 fi
 
-# 6. Timeshift Boot Snapshot Service & APT Update Hook (if on Btrfs)
+# 6. Timeshift Boot Snapshot Service, APT Update Hook & GRUB Btrfs Daemon (if on Btrfs)
-log_substep "Configuring Timeshift Boot Snapshot Service and APT Update Hook..."
+log_substep "Configuring Timeshift Boot Snapshot Service, APT Update Hook and GRUB Btrfs Snapshot Daemon..."
 if command_exists timeshift && is_root_btrfs; then
     ensure_timeshift_btrfs_config
-    log_success "Timeshift Boot Snapshot Service and APT Update Hook configured and enabled."
+    ensure_grub_btrfs
+    log_success "Timeshift and GRUB Btrfs snapshot services configured and enabled."
 elif is_root_btrfs; then
-    log_info "Timeshift will be configured when installed."
+    ensure_grub_btrfs
+    log_info "Timeshift will be configured when installed; grub-btrfs configured."
 fi
 
 # 7. User Group Memberships