diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index c7203a4..2ebcc7c 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -59,6 +59,7 @@ jobs:
               ./tests/partial-release.sh
               ./tests/published-build-plan.sh
               ./tests/settings-boot-config.sh
+              ./tests/settings-runtime-profile.sh
               ./tests/pinned-sources.sh
               ./tests/controller.sh
               ./tests/artifact-helpers.sh
diff --git a/pkgbuilds/omarchy-settings/PKGBUILD b/pkgbuilds/omarchy-settings/PKGBUILD
index 2043463..7a2cb4a 100644
--- a/pkgbuilds/omarchy-settings/PKGBUILD
+++ b/pkgbuilds/omarchy-settings/PKGBUILD
@@ -13,14 +13,17 @@ pkgname='omarchy-settings'
 _tag='v4.0.4'
 _commit='c668141e9c42b13c80c9ca4ea108e11708c5e8a5'
 pkgver=4.0.4
-pkgrel=3
+pkgrel=4
 pkgdesc='Omarchy user defaults, /etc/skel content, fonts, plymouth theme, and support helpers'
 # Arch-specific because the shipped /etc tree is not the same on every
-# architecture: the zram and oomd drop-ins belong to the x86_64 memory stack
-# and are left out of the aarch64 package (see package()). The Limine and
-# mkinitcpio drop-ins ship on both: UEFI aarch64 installs (DGX Spark,
-# Snapdragon X) boot with Limine and an encrypted root exactly like x86_64.
-# makepkg only honours the arch-suffixed arrays below on arch-specific packages.
+# architecture for older sources: their zram and oomd drop-ins belong to the
+# x86_64 memory stack and are left out of the aarch64 package (see package()).
+# The Limine and mkinitcpio drop-ins ship on both: UEFI aarch64 installs (DGX
+# Spark, Snapdragon X) boot with Limine and an encrypted root exactly like
+# x86_64. A source with default/settings-runtime-profile decides at runtime
+# which platform-specific files apply, and its aarch64 package ships the same
+# files as x86_64. makepkg only honours the arch-suffixed arrays below on
+# arch-specific packages.
 arch=('x86_64' 'aarch64')
 url='https://github.com/basecamp/omarchy'
 license=('MIT')
@@ -86,14 +89,16 @@ backup+=(
   'etc/limine-entry-tool.d/omarchy-uki.conf'
 )
 # backup has no arch-suffixed form, so the x86_64-only drop-ins join it here.
-# Each of these paths is removed from the aarch64 package in package().
+# Each of these paths is removed from an older source's aarch64 package in
+# package(), which adds them back for a runtime-profile source.
+_x86_64_backup=(
+  'etc/mkinitcpio.conf.d/thunderbolt_module.conf'
+  'etc/modprobe.d/omarchy-usb-autosuspend.conf'
+  'etc/systemd/oomd.conf.d/10-omarchy.conf'
+  'etc/systemd/zram-generator.conf'
+)
 if [[ $CARCH == x86_64 ]]; then
-  backup+=(
-    'etc/mkinitcpio.conf.d/thunderbolt_module.conf'
-    'etc/modprobe.d/omarchy-usb-autosuspend.conf'
-    'etc/systemd/oomd.conf.d/10-omarchy.conf'
-    'etc/systemd/zram-generator.conf'
-  )
+  backup+=("${_x86_64_backup[@]}")
 fi
 
 optdepends=(
@@ -160,6 +165,20 @@ _omarchy_settings_hooks_after() {
 package() {
   cd "$srcdir/omarchy"
 
+  # A source that decides at runtime which platform-specific files apply (see
+  # default/settings-runtime-profile in it) ships its whole tree on aarch64,
+  # with the same backup and optdepends as x86_64. Older sources still leave
+  # the x86_64 memory stack out there.
+  local legacy_aarch64=0
+  if [[ $CARCH == aarch64 ]]; then
+    if [[ -f default/settings-runtime-profile ]]; then
+      backup+=("${_x86_64_backup[@]}")
+      optdepends+=("${optdepends_x86_64[@]}")
+    else
+      legacy_aarch64=1
+    fi
+  fi
+
   # /etc/skel/.config from config/** — system-wide default user config.
   # Package-owned defaults that live elsewhere in the system belong under
   # default/** or etc/** instead.
@@ -202,12 +221,16 @@ package() {
   install -Dm644 default/systemd/user/omarchy-tailscale-receive.service "$pkgdir/usr/lib/systemd/user/omarchy-tailscale-receive.service"
   install -Dm644 default/systemd/user/omarchy-fcitx5.service "$pkgdir/usr/lib/systemd/user/omarchy-fcitx5.service"
   install -Dm644 default/systemd/user/omarchy-crash-watch.service "$pkgdir/usr/lib/systemd/user/omarchy-crash-watch.service"
+  # First-run enables this unit, so it ships wherever the source has it.
+  if [[ -f default/systemd/user/omarchy-brightness-keyboard-auto.service ]]; then
+    install -Dm644 default/systemd/user/omarchy-brightness-keyboard-auto.service "$pkgdir/usr/lib/systemd/user/omarchy-brightness-keyboard-auto.service"
+  fi
   # Marks app.slice (and only app.slice) as a systemd-oomd kill candidate, so
   # memory pressure costs one app scope instead of the compositor session.
   # Thresholds live in etc/systemd/oomd.conf.d/10-omarchy.conf. Both this and
-  # the zram vendor drop-in belong to the x86_64 memory stack: the aarch64
-  # install neither enables systemd-oomd nor configures zram swap.
-  if [[ $CARCH == x86_64 ]]; then
+  # the zram vendor drop-in belong to the x86_64 memory stack: an older
+  # source's aarch64 install neither enables systemd-oomd nor configures zram.
+  if (( ! legacy_aarch64 )); then
     install -Dm644 default/systemd/user/app.slice.d/10-oomd.conf "$pkgdir/usr/lib/systemd/user/app.slice.d/10-oomd.conf"
     install -Dm644 default/systemd/zram-generator.conf.d/90-omarchy.conf "$pkgdir/usr/lib/systemd/zram-generator.conf.d/90-omarchy.conf"
   fi
@@ -234,22 +257,25 @@ package() {
   if [[ $CARCH == aarch64 ]]; then
     # Keep omarchy_hooks.conf and the Limine entry-tool config: without them a
     # kernel update on an encrypted aarch64 install rebuilds an initramfs with
-    # no encrypt hook and the machine cannot unlock its root. Only the
+    # no encrypt hook and the machine cannot unlock its root. An older source's
     # Thunderbolt module request is x86-specific; ARM kernels lack the module
-    # and mkinitcpio treats a missing explicit module as an error.
-    rm -f "$pkgdir/etc/mkinitcpio.conf.d/thunderbolt_module.conf"
+    # and mkinitcpio treats a missing explicit module as an error. A
+    # runtime-profile source adds it only where the kernel has the module.
+    (( ! legacy_aarch64 )) || rm -f "$pkgdir/etc/mkinitcpio.conf.d/thunderbolt_module.conf"
     # Apple Silicon Macs install this package too. Their initramfs needs the
     # asahi hook, which omarchy-mac-boot's 90-94 fragments (Aurora) or
     # mkinitcpio.conf (legacy GRUB Macs) set, and an unconditional HOOKS= here
-    # would replace it. A source that sets HOOKS outright (v4.0.4) gets its line
-    # wrapped so it applies only when the hooks loaded so far lack asahi; one that
-    # already decides per platform (omacom/omarchy#13362) ships as it is. The
-    # wrapper reads configuration, not the running machine, so it also holds
-    # when the image is built in a chroot.
+    # would replace it. An older source that sets HOOKS outright (v4.0.4) gets
+    # its line wrapped so it applies only when the hooks loaded so far lack
+    # asahi; one that already decides per platform (omacom/omarchy#13362), and
+    # every runtime-profile source, ships as it is. The wrapper reads
+    # configuration, not the running machine, so it also holds when the image
+    # is built in a chroot.
     local hooks_conf hooks_confs=()
     for hooks_conf in "$pkgdir"/etc/mkinitcpio.conf.d/{00-omarchy-hooks,omarchy_hooks}.conf; do
       [[ -f $hooks_conf ]] || continue
       hooks_confs+=("$hooks_conf")
+      (( legacy_aarch64 )) || continue
       sed -i 's/^\(HOOKS=([^#]*)\)[[:space:]]*$/if [[ " ${HOOKS[*]:-} " != *" asahi "* ]]; then\n  \1\nfi/' "$hooks_conf"
       if grep -q '^HOOKS=' "$hooks_conf"; then
         echo "${hooks_conf#"$pkgdir"/}: cannot guard this HOOKS= line for Apple Silicon" >&2
@@ -266,9 +292,12 @@ package() {
       echo "etc/mkinitcpio.conf.d: the aarch64 hooks must keep a Mac's asahi line and set everyone else's" >&2
       return 1
     fi
-    # Memory stack: no zram device or zswap on the aarch64 install, and
-    # systemd-oomd is not enabled there, so the vm.* reclaim tuning written
-    # for zram would be wrong for it. Keep only the network tuning.
+  fi
+  if (( legacy_aarch64 )); then
+    # Memory stack: no zram device or zswap on an older source's aarch64
+    # install, and systemd-oomd is not enabled there, so the vm.* reclaim
+    # tuning written for zram would be wrong for it. Keep only the network
+    # tuning.
     rm -rf "$pkgdir/etc/systemd/oomd.conf.d"
     rm -f "$pkgdir/etc/systemd/zram-generator.conf" "$pkgdir/etc/tmpfiles.d/omarchy-zswap.conf"
     cat >"$pkgdir/etc/sysctl.d/99-omarchy-sysctl.conf" <<'EOF'
diff --git a/tests/settings-runtime-profile.sh b/tests/settings-runtime-profile.sh
new file mode 100755
index 0000000..0fd375b
--- /dev/null
+++ b/tests/settings-runtime-profile.sh
@@ -0,0 +1,214 @@
+#!/bin/bash
+# Run the omarchy-settings recipe's package() against synthetic source trees:
+# an older source keeps today's per-architecture package, and a source that
+# selects its platform profile at runtime ships the same files, backup and
+# optdepends on aarch64 as on x86_64.
+set -euo pipefail
+export LC_ALL=C
+
+BUILD_ROOT=$(realpath "${BASH_SOURCE[0]%/*}/..")
+scratch=$(mktemp -d)
+trap 'rm -rf "$scratch"' EXIT
+
+fail() {
+  printf 'FAIL: %s\n' "$@" >&2
+  exit 1
+}
+
+files=(
+  applications/example.desktop
+  bin/omarchy-debug
+  bin/omarchy-debug-idle
+  bin/omarchy-hw-platform
+  bin/omarchy-upload-log
+  config/autostart/limine-snapper-notify.desktop
+  config/hypr/hyprland.lua
+  default/applications/mimeapps.list
+  default/bashrc
+  default/environment.d/10-omarchy-fcitx.conf
+  default/fontconfig/conf.avail/50-omarchy.conf
+  default/fonts/omarchy/omarchy.ttf
+  default/hypr/toggles/flags.lua
+  default/libalpm/hooks/00-omarchy-platform-guard.hook
+  default/libalpm/scripts/omarchy-platform-guard
+  default/limine/default.conf
+  default/limine/limine.conf
+  default/nautilus-python/extensions/localsend.py
+  default/nautilus-python/extensions/transcode.py
+  default/plymouth/omarchy.plymouth
+  default/sddm/hyprland.lua
+  default/sddm/omarchy/Main.qml
+  default/snapper/root
+  default/systemd/system-sleep/unmount-fuse
+  default/systemd/system/plocate-updatedb.service.d/10-omarchy.conf
+  default/systemd/user/app.slice.d/10-oomd.conf
+  default/systemd/user/bt-agent.service
+  default/systemd/user/omarchy-crash-watch.service
+  default/systemd/user/omarchy-fcitx5.service
+  default/systemd/user/omarchy-migrate-notify.service
+  default/systemd/user/omarchy-recover-internal-monitor.service
+  default/systemd/user/omarchy-sleep-lock.service
+  default/systemd/user/omarchy-tailscale-receive.service
+  default/systemd/zram-generator.conf.d/90-omarchy.conf
+  default/tensaku/state.toml
+  default/uwsm/env.d/10-omarchy
+  default/wayland-sessions/omarchy.desktop
+  default/xdg-terminal-exec/hyprland-xdg-terminals.list
+  etc/cups/cups-browsed.conf
+  etc/cups/cups-files.conf
+  etc/fastfetch/config.jsonc
+  etc/limine-entry-tool.d/omarchy-defaults.conf
+  etc/limine-entry-tool.d/omarchy-uki.conf
+  etc/mkinitcpio.conf.d/omarchy_hooks.conf
+  etc/mkinitcpio.conf.d/thunderbolt_module.conf
+  etc/modprobe.d/omarchy-usb-autosuspend.conf
+  etc/nsswitch.conf
+  etc/plymouth/plymouthd.conf
+  etc/security/faillock.conf
+  etc/sysctl.d/99-omarchy-sysctl.conf
+  etc/systemd/oomd.conf.d/10-omarchy.conf
+  etc/systemd/zram-generator.conf
+  etc/tmpfiles.d/omarchy-zswap.conf
+  icon.png
+  icon.txt
+  logo.svg
+  logo.txt
+)
+# Left out of an older source's aarch64 package, and nothing else is. Its boot
+# drop-ins ship on both (omacom/omarchy-pkgs#380).
+legacy_aarch64_absent=(
+  etc/mkinitcpio.conf.d/thunderbolt_module.conf
+  etc/modprobe.d/omarchy-usb-autosuspend.conf
+  etc/systemd/oomd.conf.d/10-omarchy.conf
+  etc/systemd/zram-generator.conf
+  etc/tmpfiles.d/omarchy-zswap.conf
+  usr/lib/systemd/user/app.slice.d/10-oomd.conf
+  usr/lib/systemd/zram-generator.conf.d/90-omarchy.conf
+)
+x86_backup=(
+  etc/mkinitcpio.conf.d/thunderbolt_module.conf
+  etc/modprobe.d/omarchy-usb-autosuspend.conf
+  etc/systemd/oomd.conf.d/10-omarchy.conf
+  etc/systemd/zram-generator.conf
+)
+keyboard_unit=default/systemd/user/omarchy-brightness-keyboard-auto.service
+platform_guard=(
+  usr/share/libalpm/hooks/00-omarchy-platform-guard.hook
+  usr/share/libalpm/scripts/omarchy-hw-platform
+  usr/share/libalpm/scripts/omarchy-platform-guard
+)
+
+# $1: source tree. Extra arguments are files to add to it.
+make_source() {
+  local tree=$1 path
+  shift
+  for path in "${files[@]}" "$@"; do
+    mkdir -p "$(dirname "$tree/$path")"
+    printf 'fixture for %s\n' "$path" >"$tree/$path"
+  done
+}
+
+# Runs package() as makepkg would for one architecture (arch-specific arrays
+# merged first) and records the package tree and its metadata. $1: recipe,
+# $2: source tree, $3: CARCH, $4: output name, $5: "checkout" to build through
+# OMARCHY_SRC, "pinned" for the git source.
+package_as() {
+  local recipe=$1 tree=$2 carch=$3 name=$4 mode=$5
+  (
+    unset OMARCHY_SRC
+    [[ $mode == "pinned" ]] || export OMARCHY_SRC=$tree
+    export CARCH=$carch srcdir=$scratch/$name-src pkgdir=$scratch/$name
+    mkdir -p "$srcdir" "$pkgdir"
+    ln -sfn "$tree" "$srcdir/omarchy"
+    backup=()
+    # shellcheck disable=SC1090 # Exercise the recipe's own package function.
+    source "$BUILD_ROOT/pkgbuilds/$recipe/PKGBUILD"
+    eval "optdepends+=(\"\${optdepends_${carch}[@]}\")"
+    package
+    printf '%s\n' "${backup[@]}" | sort >"$scratch/$name.backup"
+    # shellcheck disable=SC2154 # Set by the recipe.
+    printf '%s\n' "${optdepends[@]}" >"$scratch/$name.optdepends"
+    (cd "$pkgdir" && find . \( -type f -o -type l \) | sed 's|^\./||' | sort) >"$scratch/$name.files"
+  )
+}
+
+in_list() {
+  grep -Fxq -- "$1" "$2"
+}
+
+fixtures=$BUILD_ROOT/tests/fixtures/settings-boot
+make_source "$scratch/legacy"
+cp "$fixtures/omarchy_hooks-v4.0.4.conf" "$scratch/legacy/etc/mkinitcpio.conf.d/omarchy_hooks.conf"
+make_source "$scratch/profile" default/settings-runtime-profile "$keyboard_unit"
+cp "$fixtures"/omarchy-13362/*.conf "$scratch/profile/etc/mkinitcpio.conf.d/"
+
+for recipe in omarchy-settings; do
+  rm -rf "${scratch:?}"/legacy-* "${scratch:?}"/profile-*
+  # An older source keeps the per-architecture package it has always had.
+  package_as "$recipe" "$scratch/legacy" x86_64 legacy-x86_64 pinned
+  package_as "$recipe" "$scratch/legacy" aarch64 legacy-aarch64 pinned
+  for path in "${legacy_aarch64_absent[@]}"; do
+    in_list "$path" "$scratch/legacy-x86_64.files" || fail "older source ships $path on x86_64"
+    ! in_list "$path" "$scratch/legacy-aarch64.files" || fail "older source leaves $path out on aarch64"
+  done
+  missing=$(comm -23 "$scratch/legacy-x86_64.files" "$scratch/legacy-aarch64.files")
+  [[ $missing == "$(printf '%s\n' "${legacy_aarch64_absent[@]}" | sort)" ]] ||
+    fail "older source's aarch64 package differs from x86_64 only by the boot and memory drop-ins" "$missing"
+  grep -Fxq 'if [[ " ${HOOKS[*]:-} " != *" asahi "* ]]; then' "$scratch/legacy-aarch64/etc/mkinitcpio.conf.d/omarchy_hooks.conf" ||
+    fail "older source's aarch64 HOOKS line applies only without asahi"
+  cmp -s "$scratch/legacy/etc/mkinitcpio.conf.d/omarchy_hooks.conf" "$scratch/legacy-x86_64/etc/mkinitcpio.conf.d/omarchy_hooks.conf" ||
+    fail 'x86_64 ships the source HOOKS line as it is'
+  cmp -s "$scratch/legacy/etc/sysctl.d/99-omarchy-sysctl.conf" "$scratch/legacy-x86_64/etc/sysctl.d/99-omarchy-sysctl.conf" ||
+    fail 'x86_64 ships the source sysctl file'
+  ! cmp -s "$scratch/legacy/etc/sysctl.d/99-omarchy-sysctl.conf" "$scratch/legacy-aarch64/etc/sysctl.d/99-omarchy-sysctl.conf" ||
+    fail 'older source keeps only the network tuning on aarch64'
+  for path in "${x86_backup[@]}"; do
+    in_list "$path" "$scratch/legacy-x86_64.backup" || fail "x86_64 backs up $path"
+    ! in_list "$path" "$scratch/legacy-aarch64.backup" || fail "older source's aarch64 backup leaves out $path"
+  done
+  for path in etc/mkinitcpio.conf.d/omarchy_hooks.conf etc/limine-entry-tool.d/omarchy-defaults.conf; do
+    in_list "$path" "$scratch/legacy-aarch64.backup" || fail "older source's aarch64 package backs up $path"
+  done
+  grep -q '^limine:' "$scratch/legacy-x86_64.optdepends" || fail 'x86_64 suggests the boot stack its drop-ins are for'
+  ! grep -q '^limine:' "$scratch/legacy-aarch64.optdepends" || fail "older source's aarch64 package suggests no boot stack"
+  ! in_list usr/lib/systemd/user/omarchy-brightness-keyboard-auto.service "$scratch/legacy-x86_64.files" ||
+    fail 'a source without the keyboard unit ships none'
+  echo "PASS: $recipe: an older source keeps its per-architecture package"
+
+  # A runtime-profile source ships the same tree and metadata on both.
+  package_as "$recipe" "$scratch/profile" x86_64 profile-x86_64 checkout
+  package_as "$recipe" "$scratch/profile" aarch64 profile-aarch64 pinned
+  # The pacman platform guard is the profile's one exception: aarch64 only
+  # where the recipe says so (omacom/omarchy-pkgs#691).
+  for path in "${platform_guard[@]}"; do
+    in_list "$path" "$scratch/profile-aarch64.files" || fail "aarch64 ships the platform guard's $path"
+  done
+  grep -Fxv -f <(printf '%s\n' "${platform_guard[@]}") "$scratch/profile-x86_64.files" >"$scratch/profile-x86_64.compared"
+  grep -Fxv -f <(printf '%s\n' "${platform_guard[@]}") "$scratch/profile-aarch64.files" >"$scratch/profile-aarch64.compared"
+  cmp -s "$scratch/profile-x86_64.compared" "$scratch/profile-aarch64.compared" ||
+    fail 'runtime-profile source ships the same files on both architectures' \
+      "$(diff "$scratch/profile-x86_64.compared" "$scratch/profile-aarch64.compared")"
+  while IFS= read -r path; do
+    if [[ -L $scratch/profile-x86_64/$path ]]; then
+      [[ $(readlink "$scratch/profile-x86_64/$path") == "$(readlink "$scratch/profile-aarch64/$path")" ]]
+    else
+      cmp -s "$scratch/profile-x86_64/$path" "$scratch/profile-aarch64/$path"
+    fi || fail "runtime-profile source ships the same $path on both architectures"
+  done <"$scratch/profile-x86_64.files"
+  cmp -s "$scratch/profile-x86_64.backup" "$scratch/profile-aarch64.backup" ||
+    fail 'runtime-profile source backs up the same files on both architectures'
+  cmp -s "$scratch/profile-x86_64.optdepends" "$scratch/profile-aarch64.optdepends" ||
+    fail 'runtime-profile source has the same optdepends on both architectures'
+  in_list etc/mkinitcpio.conf.d/00-omarchy-hooks.conf "$scratch/profile-x86_64.backup" ||
+    fail 'the HOOKS baseline drop-in is backed up where the source has it'
+  in_list usr/lib/systemd/user/omarchy-brightness-keyboard-auto.service "$scratch/profile-aarch64.files" ||
+    fail 'the keyboard unit first-run enables ships when the source has it'
+  comm -13 "$scratch/legacy-x86_64.files" "$scratch/profile-x86_64.files" >"$scratch/added"
+  for conf in 00-omarchy-hooks.conf omarchy_hooks.conf; do
+    cmp -s "$fixtures/omarchy-13362/$conf" "$scratch/profile-aarch64/etc/mkinitcpio.conf.d/$conf" ||
+      fail "runtime-profile source ships its $conf as it is on aarch64"
+  done
+  [[ $(cat "$scratch/added") == "$(printf '%s\n' usr/lib/systemd/user/omarchy-brightness-keyboard-auto.service usr/share/omarchy/default/settings-runtime-profile "usr/share/omarchy/$keyboard_unit" etc/mkinitcpio.conf.d/00-omarchy-hooks.conf | sort)" ]] ||
+    fail 'x86_64 gains only the new source files from a runtime-profile source' "$(cat "$scratch/added")"
+  echo "PASS: $recipe: a runtime-profile source ships the full set on aarch64"
+done