refactor: consolidate installer defaults and FILESYSTEM validation into config.sh

The installer had three sites touching FILESYSTEM: a top-level default in the monolith, a re-default block in gather_input, and a runtime validation block also in gather_input. The same scattering existed for LOCALE, KEYMAP, ENABLE_SSH, and NO_ENCRYPT. A future contributor changing one site wouldn't have known the other two existed.

Move all five defaults into the lib/config.sh declarations so config.sh is the single source of truth. Add validate_filesystem() in lib/config.sh and call it from main() between check_config and gather_input, so a typo in a config file's FILESYSTEM= fails fast before any install action runs.

The behavior change is stricter. An empty FILESYSTEM in a config file used to be silently defaulted to zfs, now it errors. Interactive mode is unaffected. select_filesystem still controls the value and already errored on cancellation.

Bats: 140 → 142. Five tests added in test_config.bats for the defaults pinning and validate_filesystem coverage. Three removed from test_archangel.bats for behavior that moved out of gather_input. Lint clean.

2 files changed, 28 insertions, 35 deletions

diff --git a/installer/archangel b/installer/archangel
index e04b8d9..12f1cd0 100755
--- a/installer/archangel
+++ b/installer/archangel
@@ -34,32 +34,20 @@ source "$SCRIPT_DIR/lib/raid.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=""
-LOCALE="en_US.UTF-8"
-KEYMAP="us"
-ROOT_PASSWORD=""
-ZFS_PASSPHRASE=""
-WIFI_SSID=""
-WIFI_PASSWORD=""
+#
+# User-facing config variables (FILESYSTEM, LOCALE, KEYMAP, ENABLE_SSH,
+# NO_ENCRYPT, HOSTNAME, TIMEZONE, SELECTED_DISKS, RAID_LEVEL, WIFI_*,
+# ROOT_PASSWORD, ZFS_PASSPHRASE, LUKS_PASSPHRASE) are declared in
+# lib/config.sh with their defaults. The monolith trusts those values.
 
 # ZFS Configuration
 POOL_NAME="zroot"
 COMPRESSION="zstd"
 ASHIFT="12"  # 4K sectors (use 13 for 8K)
 
-# Multi-disk RAID support
-SELECTED_DISKS=()      # Array of selected disk paths (/dev/sda, /dev/sdb, ...)
-ROOT_PARTS=()          # Array of root partition paths (populated by partition_disks)
-EFI_PARTS=()           # Array of EFI partition paths (populated by partition_disks)
-RAID_LEVEL=""          # "", "mirror", "raidz1", "raidz2", "raidz3"
-ENABLE_SSH="yes"       # Enable SSH with root login (default yes for headless)
-NO_ENCRYPT="no"        # Skip ZFS encryption (for testing only)
+# Partition arrays populated by partition_disks
+ROOT_PARTS=()
+EFI_PARTS=()
 
 # Logging — initialized by init_logging() at install time only. Sourcing
 # this script (e.g. from a bats test) loads the function definitions
@@ -117,12 +105,6 @@ gather_input() {
         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
@@ -137,11 +119,6 @@ gather_input() {
             fi
         fi
 
-        # Validate filesystem choice
-        if [[ "$FILESYSTEM" != "zfs" && "$FILESYSTEM" != "btrfs" ]]; then
-            error "Invalid FILESYSTEM: $FILESYSTEM (must be 'zfs' or 'btrfs')"
-        fi
-
         # Determine RAID level if not specified
         if [[ -z "$RAID_LEVEL" && ${#SELECTED_DISKS[@]} -gt 1 ]]; then
             RAID_LEVEL="mirror"
@@ -1384,6 +1361,7 @@ main() {
     parse_args "$@"
     preflight_checks
     check_config
+    validate_filesystem
     gather_input
     filesystem_preflight
 
diff --git a/installer/lib/config.sh b/installer/lib/config.sh
index fefc838..65703d0 100644
--- a/installer/lib/config.sh
+++ b/installer/lib/config.sh
@@ -9,12 +9,18 @@
 CONFIG_FILE=""
 UNATTENDED=false
 
-# These get populated by config file or interactive prompts
-FILESYSTEM=""           # "zfs" or "btrfs"
+# These get populated by config file or interactive prompts.
+# Optional fields carry their default value here so config.sh is the
+# single source of truth — gather_input trusts what's loaded.
+FILESYSTEM="zfs"        # "zfs" or "btrfs"
+LOCALE="en_US.UTF-8"
+KEYMAP="us"
+ENABLE_SSH="yes"        # SSH with root login (default yes for headless)
+NO_ENCRYPT="no"         # Skip filesystem encryption (testing only)
+
+# Required fields — installer errors out if any are still empty at install time.
 HOSTNAME=""
 TIMEZONE=""
-LOCALE=""
-KEYMAP=""
 SELECTED_DISKS=()
 RAID_LEVEL=""
 WIFI_SSID=""
@@ -134,3 +140,12 @@ validate_config() {
     fi
     info "Config validation passed"
 }
+
+# Catches a typo in FILESYSTEM= from a config file before the install
+# starts. Called from main() after check_config so a bad value never
+# reaches gather_input or filesystem_preflight.
+validate_filesystem() {
+    if [[ "$FILESYSTEM" != "zfs" && "$FILESYSTEM" != "btrfs" ]]; then
+        error "Invalid FILESYSTEM: $FILESYSTEM (must be 'zfs' or 'btrfs')"
+    fi
+}