Ship zram tuning as a vendor drop-in

pacman checks file conflicts during transaction prepare, so the --overwrite
entry added alongside /etc/systemd/zram-generator.conf never got to run: the
copy of omarchy-update-system-pkgs driving the upgrade is the one already on
disk. Every machine carrying archinstall's copy aborted the transaction.

zram-generator.conf(5) reserves /etc for the local admin and has vendors ship
snippets under /usr/lib/systemd/zram-generator.conf.d/, where drop-ins outrank
the main config file. Nothing collides, and the tuning wins whether or not
archinstall's file is still around.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LjeyQZsNBxqyYy9z8KaKm7

test/shell.d/config-test.sh

@@ -122,6 +122,7 @@ package_defaults = [
   ("default/systemd/user/omarchy-recover-internal-monitor.service", "/usr/lib/systemd/user/omarchy-recover-internal-monitor.service", "systemd/user/omarchy-recover-internal-monitor.service"),
   ("default/systemd/user/omarchy-update-user-notify.service", "/usr/lib/systemd/user/omarchy-update-user-notify.service", "systemd/user/omarchy-update-user-notify.service"),
   ("default/systemd/user/omarchy-update-user-notify.path", "/usr/lib/systemd/user/omarchy-update-user-notify.path", "systemd/user/omarchy-update-user-notify.path"),
+  ("default/systemd/zram-generator.conf.d/90-omarchy.conf", "/usr/lib/systemd/zram-generator.conf.d/90-omarchy.conf", "systemd/zram-generator.conf.d/90-omarchy.conf"),
   ("default/fonts/omarchy/omarchy.ttf", "/usr/share/fonts/omarchy/omarchy.ttf", "omarchy.ttf"),
   ("default/snapper/root", "/etc/snapper/config-templates/omarchy", "snapper/root"),
 ]

test/shell.d/zram-migration-test.sh

@@ -0,0 +1,87 @@
+#!/bin/bash
+
+source "$(dirname "${BASH_SOURCE[0]}")/base-test.sh"
+
+migration=$(grep -rl 'Move zram tuning to a vendor drop-in' "$ROOT/migrations" | head -n 1 || true)
+[[ -n $migration ]] || fail "zram drop-in migration exists"
+
+TMPDIR=$(mktemp -d)
+trap 'rm -rf "$TMPDIR"' EXIT
+
+# The migration shells out to pacman (ownership check) and sudo (removal).
+# Stub both so the test never touches the real system, and let each case pick
+# what `pacman -Qo` reports through PACMAN_OWNS.
+stub_bin="$TMPDIR/bin"
+mkdir -p "$stub_bin"
+
+cat >"$stub_bin/pacman" <<'STUB'
+#!/bin/bash
+[[ ${PACMAN_OWNS:-0} == 1 ]]
+STUB
+
+cat >"$stub_bin/sudo" <<'STUB'
+#!/bin/bash
+exec "$@"
+STUB
+
+chmod +x "$stub_bin/pacman" "$stub_bin/sudo"
+
+# omarchy-migrate runs each migration with `bash -euo pipefail` and stops the
+# whole chain on a non-zero exit, so match that invocation exactly.
+run_migration() {
+  local conf="$1"
+  PATH="$stub_bin:$PATH" OMARCHY_ZRAM_CONF="$conf" \
+    bash -euo pipefail "$migration" >/dev/null ||
+    fail "migration exits clean for $(basename "$conf")"
+}
+
+# archinstall's own output: a [zram0] section with nothing but the algorithm.
+conf="$TMPDIR/archinstall.conf"
+printf '[zram0]\ncompression-algorithm = zstd\n' >"$conf"
+run_migration "$conf"
+[[ -f $conf ]] && fail "migration removes archinstall's generated config"
+pass "migration removes archinstall's generated config"
+
+# Same shape, different algorithm, plus comments and blank lines.
+conf="$TMPDIR/commented.conf"
+printf '# written by archinstall\n\n[zram0]\ncompression-algorithm = lz4\n\n' >"$conf"
+run_migration "$conf"
+[[ -f $conf ]] && fail "migration ignores comments and a non-zstd algorithm"
+pass "migration ignores comments and a non-zstd algorithm"
+
+# A config that sets nothing decides nothing, and must not take the migration
+# chain down with it.
+conf="$TMPDIR/comments-only.conf"
+printf '# nothing to see here\n\n' >"$conf"
+run_migration "$conf"
+[[ -f $conf ]] && fail "migration removes a config that sets nothing"
+pass "migration removes a config that sets nothing"
+
+conf="$TMPDIR/empty.conf"
+: >"$conf"
+run_migration "$conf"
+[[ -f $conf ]] && fail "migration removes an empty config"
+pass "migration removes an empty config"
+
+# A local override must survive.
+conf="$TMPDIR/local.conf"
+printf '[zram0]\ncompression-algorithm = zstd\nzram-size = ram / 4\n' >"$conf"
+run_migration "$conf"
+[[ -f $conf ]] || fail "migration keeps a locally edited config"
+pass "migration keeps a locally edited config"
+
+# Package-owned copies go away with their package; the migration must not touch
+# them.
+conf="$TMPDIR/owned.conf"
+printf '[zram0]\ncompression-algorithm = zstd\n' >"$conf"
+PATH="$stub_bin:$PATH" PACMAN_OWNS=1 OMARCHY_ZRAM_CONF="$conf" \
+  bash -euo pipefail "$migration" >/dev/null ||
+  fail "migration exits clean for a package-owned config"
+[[ -f $conf ]] || fail "migration keeps a package-owned config"
+pass "migration keeps a package-owned config"
+
+# Nothing to do, and running twice must stay clean.
+conf="$TMPDIR/absent.conf"
+run_migration "$conf"
+run_migration "$conf"
+pass "migration no-ops when the config is already gone"