refactor: unify partition_disks across ZFS and Btrfs install paths

The monolith's partition_disks() at installer/archangel was ZFS-only and silently shadowed lib/disk.sh:partition_disks(), which had been dead code since the Btrfs install path was added. install_btrfs was assembling partitioning manually via partition_disk (singular) plus a separate format_efi_partitions call. Two parallel implementations meant fixes had to land in two places and the lib version drifted with no visible warning.

The unified partition_disks now lives in lib/disk.sh. It reads SELECTED_DISKS, dispatches the per-disk layout on FILESYSTEM (BF00 for ZFS, 8300 for Btrfs), populates EFI_PARTS + ROOT_PARTS, and formats each EFI partition with EFI0, EFI1, ... labels.

Folded in two pre-existing divergences while consolidating. wipefs -af now runs on every disk, not just the ZFS path. The Btrfs path was missing this defense against non-GPT signatures (LVM, mdadm, ext) that sgdisk --zap-all alone won't touch. EFI labels standardized on EFI0, EFI1, ... across both paths. The lib version was producing asymmetric EFI / EFI2 labels. No consumer in the repo references the labels after format, so that change is cosmetic.

ZFS_PARTS renamed to ROOT_PARTS for symmetry with get_root_partition. Deleted four orphaned helpers: format_efi, format_efi_partitions (only caller was the collapsed install_btrfs section), get_efi_partitions, get_root_partitions (test-only callers after install_btrfs simplified).

Verified end to end: bats 134/134, make test-install passing 12/12 configs across both install paths.

1 files changed, 146 insertions, 44 deletions

diff --git a/tests/unit/test_disk.bats b/tests/unit/test_disk.bats
index f4e6929..1b3cfba 100644
--- a/tests/unit/test_disk.bats
+++ b/tests/unit/test_disk.bats
@@ -1,11 +1,13 @@
 #!/usr/bin/env bats
 # Unit tests for installer/lib/disk.sh
 #
-# Coverage scope: pure partition-path helpers only. Side-effecting
-# functions (partition_disk, partition_disks, format_efi,
-# format_efi_partitions, select_disks) wrap sgdisk / mkfs.fat /
-# partprobe / fzf and are validated by VM integration per the
-# project's testing-strategy.org policy.
+# Coverage scope: pure partition-path helpers (get_efi_partition,
+# get_root_partition) plus the partition_disks orchestration shape
+# (which globals get populated, which destructive tools get invoked,
+# how often). The destructive tools themselves (sgdisk, wipefs,
+# partprobe, mkfs.fat) and the interactive select_disks (fzf) are
+# validated by VM integration per the project's testing-strategy.org
+# policy.
 
 setup() {
     # shellcheck disable=SC1091
@@ -75,58 +77,158 @@ setup() {
 }
 
 #############################
-# get_efi_partitions
+# partition_disks (orchestration)
 #############################
+# partition_disks reads SELECTED_DISKS, dispatches the per-disk
+# layout (sgdisk + wipefs + mkfs.fat) on FILESYSTEM, and populates
+# EFI_PARTS + ROOT_PARTS for downstream callers (create_zfs_pool,
+# btrfs_open_encryption, sync_efi_partitions, fstab generation).
+#
+# The destructive system tools (sgdisk, wipefs, partprobe, mkfs.fat)
+# are mocked to capture invocation shape only — actual partition
+# behavior is validated by VM integration per testing-strategy.org.
 
-@test "get_efi_partitions: two SATA disks emit two suffixed partitions" {
-    run get_efi_partitions /dev/sda /dev/sdb
-    [ "$status" -eq 0 ]
-    [ "$output" = "/dev/sda1
-/dev/sdb1" ]
+partition_disks_setup() {
+    SELECTED_DISKS=()
+    EFI_PARTS=()
+    ROOT_PARTS=()
+    CALLS=()
+    sgdisk()    { CALLS+=("sgdisk $*");   return 0; }
+    wipefs()    { CALLS+=("wipefs $*");   return 0; }
+    partprobe() { CALLS+=("partprobe $*"); return 0; }
+    mkfs.fat()  { CALLS+=("mkfs.fat $*");  return 0; }
+    sleep()     { :; }
+    info()      { :; }
+    step()      { :; }
+    error()     { CALLS+=("error $*"); return 1; }
 }
 
-@test "get_efi_partitions: mixed SATA + NVMe gets correct per-disk suffix" {
-    run get_efi_partitions /dev/sda /dev/nvme0n1
-    [ "$status" -eq 0 ]
-    [ "$output" = "/dev/sda1
-/dev/nvme0n1p1" ]
+@test "partition_disks: populates EFI_PARTS and ROOT_PARTS for single SATA disk" {
+    partition_disks_setup
+    SELECTED_DISKS=(/dev/sda)
+    FILESYSTEM=zfs
+
+    partition_disks
+
+    [ "${#EFI_PARTS[@]}" -eq 1 ]
+    [ "${#ROOT_PARTS[@]}" -eq 1 ]
+    [ "${EFI_PARTS[0]}" = "/dev/sda1" ]
+    [ "${ROOT_PARTS[0]}" = "/dev/sda2" ]
 }
 
-@test "get_efi_partitions: single NVMe disk emits one p1 partition" {
-    run get_efi_partitions /dev/nvme0n1
-    [ "$status" -eq 0 ]
-    [ "$output" = "/dev/nvme0n1p1" ]
+@test "partition_disks: NVMe disk gets p1/p2 suffixes in globals" {
+    partition_disks_setup
+    SELECTED_DISKS=(/dev/nvme0n1)
+    FILESYSTEM=zfs
+
+    partition_disks
+
+    [ "${EFI_PARTS[0]}" = "/dev/nvme0n1p1" ]
+    [ "${ROOT_PARTS[0]}" = "/dev/nvme0n1p2" ]
 }
 
-@test "get_efi_partitions: three disks emit three lines in order" {
-    run get_efi_partitions /dev/sda /dev/sdb /dev/sdc
-    [ "$status" -eq 0 ]
-    local lines
-    lines=$(echo "$output" | wc -l)
-    [ "$lines" -eq 3 ]
+@test "partition_disks: multi-disk SATA populates both arrays in order" {
+    partition_disks_setup
+    SELECTED_DISKS=(/dev/sda /dev/sdb /dev/sdc)
+    FILESYSTEM=zfs
+
+    partition_disks
+
+    [ "${#EFI_PARTS[@]}" -eq 3 ]
+    [ "${#ROOT_PARTS[@]}" -eq 3 ]
+    [ "${EFI_PARTS[0]}" = "/dev/sda1" ]
+    [ "${EFI_PARTS[1]}" = "/dev/sdb1" ]
+    [ "${EFI_PARTS[2]}" = "/dev/sdc1" ]
+    [ "${ROOT_PARTS[0]}" = "/dev/sda2" ]
+    [ "${ROOT_PARTS[1]}" = "/dev/sdb2" ]
+    [ "${ROOT_PARTS[2]}" = "/dev/sdc2" ]
 }
 
-#############################
-# get_root_partitions
-#############################
+@test "partition_disks: mixed SATA + NVMe applies correct suffix per disk" {
+    partition_disks_setup
+    SELECTED_DISKS=(/dev/sda /dev/nvme0n1)
+    FILESYSTEM=zfs
 
-@test "get_root_partitions: two SATA disks emit two suffix-2 partitions" {
-    run get_root_partitions /dev/sda /dev/sdb
-    [ "$status" -eq 0 ]
-    [ "$output" = "/dev/sda2
-/dev/sdb2" ]
+    partition_disks
+
+    [ "${EFI_PARTS[0]}" = "/dev/sda1" ]
+    [ "${EFI_PARTS[1]}" = "/dev/nvme0n1p1" ]
+    [ "${ROOT_PARTS[0]}" = "/dev/sda2" ]
+    [ "${ROOT_PARTS[1]}" = "/dev/nvme0n1p2" ]
 }
 
-@test "get_root_partitions: mixed SATA + NVMe applies correct suffix per disk" {
-    run get_root_partitions /dev/sda /dev/nvme0n1
-    [ "$status" -eq 0 ]
-    [ "$output" = "/dev/sda2
-/dev/nvme0n1p2" ]
+@test "partition_disks: ZFS dispatch passes BF00 root type to sgdisk" {
+    partition_disks_setup
+    SELECTED_DISKS=(/dev/sda)
+    FILESYSTEM=zfs
+
+    partition_disks
+
+    [[ " ${CALLS[*]} " == *"sgdisk -n 2:0:0 -t 2:BF00"* ]]
 }
 
-@test "get_root_partitions: NVMe array gets p2 suffix on each entry" {
-    run get_root_partitions /dev/nvme0n1 /dev/nvme1n1
-    [ "$status" -eq 0 ]
-    [ "$output" = "/dev/nvme0n1p2
-/dev/nvme1n1p2" ]
+@test "partition_disks: Btrfs dispatch passes 8300 root type to sgdisk" {
+    partition_disks_setup
+    SELECTED_DISKS=(/dev/sda)
+    FILESYSTEM=btrfs
+
+    partition_disks
+
+    [[ " ${CALLS[*]} " == *"sgdisk -n 2:0:0 -t 2:8300"* ]]
+}
+
+@test "partition_disks: invokes wipefs -af on each disk" {
+    partition_disks_setup
+    SELECTED_DISKS=(/dev/sda /dev/sdb)
+    FILESYSTEM=zfs
+
+    partition_disks
+
+    local count
+    count=$(printf '%s\n' "${CALLS[@]}" | grep -c '^wipefs -af ')
+    [ "$count" -eq 2 ]
+    [[ " ${CALLS[*]} " == *"wipefs -af /dev/sda"* ]]
+    [[ " ${CALLS[*]} " == *"wipefs -af /dev/sdb"* ]]
+}
+
+@test "partition_disks: invokes mkfs.fat once per EFI partition with EFI<i> label" {
+    partition_disks_setup
+    SELECTED_DISKS=(/dev/sda /dev/sdb)
+    FILESYSTEM=zfs
+
+    partition_disks
+
+    local count
+    count=$(printf '%s\n' "${CALLS[@]}" | grep -c '^mkfs.fat ')
+    [ "$count" -eq 2 ]
+    [[ " ${CALLS[*]} " == *"mkfs.fat -F32 -n EFI0 /dev/sda1"* ]]
+    [[ " ${CALLS[*]} " == *"mkfs.fat -F32 -n EFI1 /dev/sdb1"* ]]
+}
+
+@test "partition_disks: re-initializes globals on second call" {
+    partition_disks_setup
+    SELECTED_DISKS=(/dev/sda /dev/sdb)
+    FILESYSTEM=zfs
+
+    partition_disks
+    [ "${#EFI_PARTS[@]}" -eq 2 ]
+
+    SELECTED_DISKS=(/dev/sdc)
+    partition_disks
+
+    [ "${#EFI_PARTS[@]}" -eq 1 ]
+    [ "${#ROOT_PARTS[@]}" -eq 1 ]
+    [ "${EFI_PARTS[0]}" = "/dev/sdc1" ]
+}
+
+@test "partition_disks: empty SELECTED_DISKS calls error and skips work" {
+    partition_disks_setup
+    SELECTED_DISKS=()
+    FILESYSTEM=zfs
+
+    partition_disks || true
+
+    [[ " ${CALLS[*]} " == *"error partition_disks: SELECTED_DISKS is empty"* ]]
+    [[ " ${CALLS[*]} " != *"sgdisk"* ]]
+    [[ " ${CALLS[*]} " != *"wipefs"* ]]
 }