Phase 1.4: Add filesystem selection prompt

- Add FILESYSTEM variable to config (zfs or btrfs)
- Add select_filesystem() function with fzf support
- Update gather_input() to prompt for filesystem in interactive mode
- Add validation for FILESYSTEM in unattended mode
- Btrfs selection errors with "not yet implemented"
- Update banner to show "Archangel" branding
- Update config example with FILESYSTEM option

Groundwork for btrfs support - filesystem choice is now captured,
installation logic gates on FILESYSTEM variable.

4 files changed, 82 insertions, 12 deletions

diff --git a/custom/install-archzfs b/custom/install-archzfs
index 6332286..f604f5c 100755
--- a/custom/install-archzfs
+++ b/custom/install-archzfs
@@ -32,6 +32,9 @@ source "$SCRIPT_DIR/lib/zfs.sh"
 # Configuration
 #############################
 
+# Filesystem selection (zfs or btrfs)
+FILESYSTEM="zfs"       # Default to ZFS, can be changed interactively or via config
+
 # These will be set interactively
 HOSTNAME=""
 TIMEZONE=""
@@ -87,15 +90,27 @@ gather_input() {
         # Validate required config values
         if [[ -z "$HOSTNAME" ]]; then error "Config missing required: HOSTNAME"; fi
         if [[ -z "$TIMEZONE" ]]; then error "Config missing required: TIMEZONE"; fi
-        if [[ "$NO_ENCRYPT" != "yes" && -z "$ZFS_PASSPHRASE" ]]; then error "Config missing required: ZFS_PASSPHRASE"; fi
         if [[ -z "$ROOT_PASSWORD" ]]; then error "Config missing required: ROOT_PASSWORD"; fi
         if [[ ${#SELECTED_DISKS[@]} -eq 0 ]]; then error "Config missing required: DISKS"; fi
 
         # Set defaults for optional values
+        [[ -z "$FILESYSTEM" ]] && FILESYSTEM="zfs" || true
         [[ -z "$LOCALE" ]] && LOCALE="en_US.UTF-8" || true
         [[ -z "$KEYMAP" ]] && KEYMAP="us" || true
         [[ -z "$ENABLE_SSH" ]] && ENABLE_SSH="yes" || true
 
+        # ZFS-specific validation
+        if [[ "$FILESYSTEM" == "zfs" ]]; then
+            if [[ "$NO_ENCRYPT" != "yes" && -z "$ZFS_PASSPHRASE" ]]; then
+                error "Config missing required: ZFS_PASSPHRASE (or set NO_ENCRYPT=yes)"
+            fi
+        fi
+
+        # Btrfs not yet implemented
+        if [[ "$FILESYSTEM" == "btrfs" ]]; then
+            error "Btrfs support not yet implemented. Use FILESYSTEM=zfs"
+        fi
+
         # Determine RAID level if not specified
         if [[ -z "$RAID_LEVEL" && ${#SELECTED_DISKS[@]} -gt 1 ]]; then
             RAID_LEVEL="mirror"
@@ -103,6 +118,7 @@ gather_input() {
         fi
 
         info "Configuration loaded:"
+        info "  Filesystem: $FILESYSTEM"
         info "  Hostname: $HOSTNAME"
         info "  Timezone: $TIMEZONE"
         info "  Locale: $LOCALE"
@@ -117,13 +133,20 @@ gather_input() {
 
     echo ""
     echo "╔═══════════════════════════════════════════════════════════════╗"
-    echo "║                     Arch Linux ZFS Root                       ║"
-    echo "║                Configuration and Installation                 ║"
+    echo "║                        Archangel                              ║"
+    echo "║            Arch Linux with Snapshot-Based Recovery            ║"
     echo "╚═══════════════════════════════════════════════════════════════╝"
     echo ""
     info "Answer all questions now. Installation will run unattended afterward."
     echo ""
 
+    select_filesystem
+
+    # Check for btrfs (not yet implemented)
+    if [[ "$FILESYSTEM" == "btrfs" ]]; then
+        error "Btrfs support not yet implemented. Please select ZFS."
+    fi
+
     get_hostname
     get_timezone
     get_locale
@@ -609,6 +632,7 @@ show_summary() {
     echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
     echo "Configuration Summary:"
     echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+    echo "  Filesystem:   $FILESYSTEM"
     echo "  Hostname:     $HOSTNAME"
     echo "  Timezone:     $TIMEZONE"
     echo "  Locale:       $LOCALE"
@@ -621,12 +645,16 @@ show_summary() {
     echo "  RAID Level:   ${RAID_LEVEL:-single (no RAID)}"
     echo "  WiFi:         ${WIFI_SSID:-Not configured}"
     echo "  SSH:          ${ENABLE_SSH:-yes} (root login)"
-    if [[ "$NO_ENCRYPT" == "yes" ]]; then
-        echo "  ZFS Pool:     $POOL_NAME (NOT encrypted)"
+    if [[ "$FILESYSTEM" == "zfs" ]]; then
+        if [[ "$NO_ENCRYPT" == "yes" ]]; then
+            echo "  ZFS Pool:     $POOL_NAME (NOT encrypted)"
+        else
+            echo "  ZFS Pool:     $POOL_NAME (encrypted)"
+        fi
+        echo "  Boot:         ZFSBootMenu on all disks (redundant)"
     else
-        echo "  ZFS Pool:     $POOL_NAME (encrypted)"
+        echo "  Boot:         GRUB + grub-btrfs (snapshot boot)"
     fi
-    echo "  Boot:         ZFSBootMenu on all disks (redundant)"
     echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
     echo ""
 
diff --git a/custom/install-archzfs.conf.example b/custom/install-archzfs.conf.example
index 0060cc0..dacf340 100644
--- a/custom/install-archzfs.conf.example
+++ b/custom/install-archzfs.conf.example
@@ -1,18 +1,27 @@
-# install-archzfs.conf - Unattended Installation Configuration
+# archangel.conf - Unattended Installation Configuration
 #
-# Copy this file to /root/install-archzfs.conf and edit values.
-# Or use: install-archzfs --config-file /path/to/your-config.conf
+# Copy this file and edit values.
+# Usage: archangel --config-file /path/to/your-config.conf
 #
 # Required fields: HOSTNAME, TIMEZONE, DISKS, ROOT_PASSWORD
-# Plus either ZFS_PASSPHRASE or NO_ENCRYPT=yes
+# For ZFS: also need ZFS_PASSPHRASE or NO_ENCRYPT=yes
 # All other fields have sensible defaults.
 
 #############################
+# Filesystem Selection
+#############################
+
+# Filesystem type (optional, default: zfs)
+# Options: zfs, btrfs
+# Note: btrfs support coming soon
+FILESYSTEM=zfs
+
+#############################
 # System Configuration
 #############################
 
 # Hostname for the installed system (required)
-HOSTNAME=archzfs
+HOSTNAME=archangel
 
 # Timezone (required) - Use format: Region/City
 # Examples: America/Los_Angeles, Europe/London, Asia/Tokyo
diff --git a/custom/lib/common.sh b/custom/lib/common.sh
index 2f8844e..c271aec 100644
--- a/custom/lib/common.sh
+++ b/custom/lib/common.sh
@@ -101,6 +101,38 @@ fzf_multi() {
 }
 
 #############################
+# Filesystem Selection
+#############################
+
+# Select filesystem type (ZFS or Btrfs)
+# Sets global FILESYSTEM variable
+select_filesystem() {
+    step "Select Filesystem"
+
+    local options=(
+        "ZFS - Native encryption, best data integrity (recommended)"
+        "Btrfs - Native Linux, GRUB snapshot boot"
+    )
+
+    local selected
+    selected=$(fzf_select "Filesystem:" "${options[@]}")
+
+    case "$selected" in
+        ZFS*)
+            FILESYSTEM="zfs"
+            info "Selected: ZFS"
+            ;;
+        Btrfs*)
+            FILESYSTEM="btrfs"
+            info "Selected: Btrfs"
+            ;;
+        *)
+            error "No filesystem selected"
+            ;;
+    esac
+}
+
+#############################
 # Disk Utilities
 #############################
 
diff --git a/custom/lib/config.sh b/custom/lib/config.sh
index cec3d8c..38811fa 100644
--- a/custom/lib/config.sh
+++ b/custom/lib/config.sh
@@ -10,6 +10,7 @@ CONFIG_FILE=""
 UNATTENDED=false
 
 # These get populated by config file or interactive prompts
+FILESYSTEM=""           # "zfs" or "btrfs"
 HOSTNAME=""
 TIMEZONE=""
 LOCALE=""