diff --git a/btrfs/README.md b/btrfs/README.md
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+# btrfs in Arcline OS
+
+Arcline OS is **btrfs-native**: the root filesystem layout is created at
+install time and snapshots are first-class, not bolted on.
+
+## Subvolume layout
+
+| Subvolume    | Mount point   | Purpose                                        |
+|--------------|---------------|------------------------------------------------|
+| `@`          | `/`           | system root — rolled back on failed upgrade    |
+| `@home`      | `/home`       | user data — not rolled back by default         |
+| `@log`       | `/var/log`    | logs survive rollbacks                         |
+| `@snapshots` | `/.snapshots` | read-only snapshots live here                  |
+
+The layout is created by `btrfs/init.sh <device>` (this is what the installer
+runs). `/etc/fstab` templates live in each edition manifest and reference these
+subvolumes with `subvol=` mount options.
+
+## Tooling
+
+- `btrfs/init.sh <device>` — create the subvolume layout on a target device.
+- `btrfs/snapshot.sh` — snapshot / list / prune. Installed in images as
+  `/usr/local/sbin/arcline-snapshot` and triggered automatically by the
+  `arcline-snapshot.timer` systemd unit (see `overlays/base/usr/lib/systemd/system/`).
+- `btrfs/rollback.sh` — promote a snapshot back to `@`. Installed as
+  `/usr/local/sbin/arcline-rollback`.
+
+## How a rollback works
+
+Rollbacks are done from a rescue/live environment (never against the mounted
+`@`). The tool moves the current `@` aside to `@.rollback-<ts>` and promotes
+the chosen snapshot to `@`. Because btrfs renames are atomic, a crash mid-way
+leaves a recoverable system on disk.
+
+## Compression
+
+All subvolumes mount with `compress=zstd:3` (see the edition `fstab`
+templates). Transparent compression is on by default.
diff --git a/btrfs/init.sh b/btrfs/init.sh
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+#!/usr/bin/env bash
+# ─────────────────────────────────────────────────────────────────────────────
+# Arcline OS — btrfs subvolume layout initialiser
+#
+#   btrfs/init.sh <device>            (e.g. /dev/sda2)
+#   btrfs/init.sh --list <device>
+#
+# Creates the Arcline subvolume layout on a fresh (or existing) btrfs device:
+#
+#     @            → /            system root (rolled back on failure)
+#     @home        → /home        user data
+#     @log         → /var/log     logs (not rolled back, survives)
+#     @snapshots   → /.snapshots  where arcline-snapshot keeps snapshots
+#
+# This is the step the installer runs; it is safe to re-run (existing
+# subvolumes are kept, missing ones are created). Requires root.
+# ─────────────────────────────────────────────────────────────────────────────
+set -euo pipefail
+
+DEV="${1:?usage: btrfs/init.sh <device>}"
+TOP="/run/arcline-btrfs-init"
+
+require_root() {
+  if [[ $EUID -ne 0 ]] && command -v sudo >/dev/null; then
+    exec sudo -E "$0" "$@"
+  elif [[ $EUID -ne 0 ]]; then
+    echo "error: needs root" >&2; exit 1
+  fi
+}
+require_root "$0" "$@"
+
+command -v btrfs >/dev/null || { echo "error: btrfs-progs not installed" >&2; exit 1; }
+
+if ! blkid -p -O "$DEV" | grep -q btrfs 2>/dev/null; then
+  echo "error: $DEV is not a btrfs filesystem" >&2
+  exit 1
+fi
+
+mkdir -p "$TOP"
+mount -o subvolid=5 "$DEV" "$TOP"
+trap 'umount "$TOP" 2>/dev/null || true; rmdir "$TOP" 2>/dev/null || true' EXIT
+
+create_subvol() {
+  local name="$1"
+  if [[ -d "$TOP/$name" ]]; then
+    echo "  keeping existing subvolume: $name"
+  else
+    echo "  creating subvolume:        $name"
+    btrfs subvolume create "$TOP/$name" >/dev/null
+  fi
+}
+
+echo "Arcline btrfs layout on $DEV:"
+create_subvol "@"
+create_subvol "@home"
+create_subvol "@log"
+create_subvol "@snapshots"
+
+# mark @snapshots read-only friendly (snapper/arcline-snapshot manage it)
+btrfs property set -ts "$TOP/@snapshots" ro false 2>/dev/null || true
+
+echo "done. The installer mounts:"
+echo "  @          → /"
+echo "  @home      → /home"
+echo "  @log       → /var/log"
+echo "  @snapshots → /.snapshots"
diff --git a/btrfs/rollback.sh b/btrfs/rollback.sh
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+++ b/btrfs/rollback.sh
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+#!/usr/bin/env bash
+# ─────────────────────────────────────────────────────────────────────────────
+# arcline-rollback — btrfs boot-to-snapshot rollback (ships at /usr/local/sbin)
+#
+#   arcline-rollback                      interactive, pick a snapshot
+#   arcline-rollback <snapshot-name>      roll back @ (and @home if present)
+#   arcline-rollback --list               list rollback targets
+#
+# Procedure (careful by design):
+#   1. must run from a rescue/live environment, OR booted into a snapshot
+#      (i.e. the active root is NOT the live @). We refuse to roll back the
+#      currently-mounted @ in place — that is what makes this safe.
+#   2. mount the btrfs top-level read-write
+#   3. move the current @ aside to @.rollback-<ts>
+#   4. promote the chosen snapshot to @
+#   5. warn about reboot (btrfs snapshotting is atomic, so a crash between
+#      steps is still recoverable by hand).
+# ─────────────────────────────────────────────────────────────────────────────
+set -euo pipefail
+
+SNAP_ROOT="/.snapshots"
+TOP="/run/arcline-btrfs-rollback"
+
+require_root() {
+  if [[ $EUID -ne 0 ]] && command -v sudo >/dev/null; then
+    exec sudo -E "$0" "$@"
+  elif [[ $EUID -ne 0 ]]; then
+    echo "error: needs root" >&2; exit 1
+  fi
+}
+
+ROOT_FS_TYPE="$(findmnt -no FSTYPE / 2>/dev/null || true)"
+if [[ "$ROOT_FS_TYPE" != "btrfs" ]]; then
+  echo "error: root filesystem is '$ROOT_FS_TYPE', not btrfs" >&2
+  exit 1
+fi
+ROOT_DEV="$(findmnt -no SOURCE / | head -1)"
+ACTIVE_ROOT="$(findmnt -no OPTIONS / | tr ',' '\n' | grep '^subvol=' | cut -d= -f2)"
+if [[ "$ACTIVE_ROOT" == "@" ]]; then
+  echo "error: the live @ root is currently mounted. Boot from a snapshot or"
+  echo "       a rescue/live environment before rolling back." >&2
+  exit 1
+fi
+
+mount_top_rw() {
+  mkdir -p "$TOP"
+  mount -o subvolid=5,rw "$ROOT_DEV" "$TOP"
+  trap 'umount "$TOP" 2>/dev/null || true; rmdir "$TOP" 2>/dev/null || true' EXIT
+}
+
+case "${1:-}" in
+  --list)
+    require_root "$0" "$@"
+    mount_top_rw
+    echo "available @ snapshots (subvolumes under @snapshots):"
+    for s in "$TOP"/@snapshots/*-@*; do
+      [[ -d "$s" ]] && echo "  $(basename "$s")"
+    done
+    ;;
+
+  "")
+    echo "usage: arcline-rollback <snapshot-name> | --list" >&2
+    exit 1
+    ;;
+
+  *)
+    require_root "$0" "$@"
+    SNAP="$1"
+    mount_top_rw
+    SRC="$TOP/@snapshots/$SNAP"
+    [[ -d "$SRC" ]] || { echo "error: snapshot '$SNAP' not found (see arcline-rollback --list)" >&2; exit 1; }
+
+    ts="$(date +%Y%m%dT%H%M%S)"
+    echo "rolling back @ to snapshot: $SNAP"
+    echo "  moving current @ → @.rollback-$ts"
+    mv "$TOP/@rolling" "$TOP/@.rollback-$ts" 2>/dev/null || true
+    mv "$TOP/@snapshots/$SNAP" "$TOP/@"
+    echo
+    echo "done. Reboot to boot into the rolled-back system."
+    echo "The previous root was kept at @.rollback-$ts; delete it once you confirm:"
+    echo "  btrfs subvolume delete '$TOP/@.rollback-$ts'"
+    ;;
+esac
diff --git a/btrfs/snapshot.sh b/btrfs/snapshot.sh
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+#!/usr/bin/env bash
+# ─────────────────────────────────────────────────────────────────────────────
+# arcline-snapshot — btrfs snapshot manager (ships at /usr/local/sbin)
+#
+#   arcline-snapshot snapshot            take a snapshot of @ and @home
+#   arcline-snapshot list                list stored snapshots
+#   arcline-snapshot prune [--keep N]    keep N newest, delete the rest
+#
+# Snapshots are read-only copies under /.snapshots, so they survive a failed
+# upgrade. Run as root (or via sudo). Configured through the
+# arcline-snapshot.timer unit (see overlays/base/usr/lib/systemd/system/).
+# ─────────────────────────────────────────────────────────────────────────────
+set -euo pipefail
+
+ACTION="${1:-list}"
+SNAP_ROOT="/.snapshots"
+KEEP="${ARCLINE_SNAPSHOT_KEEP:-5}"
+TOP="/run/arcline-btrfs"
+
+require_root() {
+  if [[ $EUID -ne 0 ]] && command -v sudo >/dev/null; then
+    exec sudo -E "$0" "$@"
+  elif [[ $EUID -ne 0 ]]; then
+    echo "error: needs root" >&2; exit 1
+  fi
+}
+
+ROOT_FS_TYPE="$(findmnt -no FSTYPE / 2>/dev/null || true)"
+if [[ "$ROOT_FS_TYPE" != "btrfs" ]]; then
+  echo "info: root filesystem is '$ROOT_FS_TYPE', not btrfs — snapshots disabled"
+  exit 0
+fi
+ROOT_DEV="$(findmnt -no SOURCE / | head -1)"
+
+mount_top() {
+  mkdir -p "$TOP"
+  mount -o subvolid=5,ro "$ROOT_DEV" "$TOP"
+  trap 'umount "$TOP" 2>/dev/null || true; rmdir "$TOP" 2>/dev/null || true' EXIT
+}
+
+stamp() { date +%Y%m%dT%H%M%S; }
+
+case "$ACTION" in
+  snapshot)
+    require_root "$0" "$@"
+    mount_top
+    ts="$(stamp)"
+    for sub in "@" "@home"; do
+      [[ -d "$TOP/$sub" ]] || { echo "warn: subvolume $sub not found, skipping"; continue; }
+      dst="$TOP/@snapshots/$ts-$sub"
+      echo "snapshotting $sub → $dst"
+      btrfs subvolume snapshot -r "$TOP/$sub" "$dst" >/dev/null
+    done
+    echo "snapshot taken: $ts"
+    ;;
+
+  list)
+    require_root "$0" "$@"
+    mount_top
+    if ! compgen -G "$TOP/@snapshots/*-@*" >/dev/null; then
+      echo "no snapshots yet"
+      exit 0
+    fi
+    for snap in "$TOP"/@snapshots/*-@*; do
+      [[ -d "$snap" ]] || continue
+      echo "$(basename "$snap")"
+    done | sort -r
+    ;;
+
+  prune)
+    require_root "$0" "$@"
+    mount_top
+    if [[ "${2:-}" == "--keep" ]]; then KEEP="${3:-$KEEP}"; fi
+    mapfile -t snaps < <(for s in "$TOP"/@snapshots/*-@*; do [[ -d "$s" ]] && echo "$s"; done | sort -r)
+    if [[ ${#snaps[@]} -le $KEEP ]]; then
+      echo "nothing to prune (${#snaps[@]} ≤ keep $KEEP)"
+      exit 0
+    fi
+    for old in "${snaps[@]:$KEEP}"; do
+      echo "deleting $(basename "$old")"
+      btrfs subvolume delete "$old" >/dev/null
+    done
+    ;;
+
+  *)
+    echo "usage: arcline-snapshot {snapshot|list|prune [--keep N]}" >&2
+    exit 1
+    ;;
+esac