diff --git a/scripts/setup/machine-setup/lib/base.sh b/scripts/setup/machine-setup/lib/base.sh
index 5308972c..5d69311b 100644
--- a/scripts/setup/machine-setup/lib/base.sh
+++ b/scripts/setup/machine-setup/lib/base.sh
@@ -163,6 +163,50 @@ confirm() {
   done
 }
 
+# Where Officer will live.
+#
+# Asked in pre-flight with the rest of the questions rather than at the point it
+# is first needed, because it decides the shape of several later steps — the
+# directory the repository is cloned into, where DATA_PATH sits beside it, and
+# which filesystem the app store's containers bind-mount out of. Answering it
+# once at the start also means the run can be described before it begins.
+#
+# One directory holding four, per docs/sidecar-app-store.md:
+#
+#   <root>/platform/       the app
+#   <root>/data/           DATA_PATH
+#   <root>/dockers/        services the app store provisioned
+#   <root>/capabilities/   the file-based item store
+#
+# OFFICER_ROOT in the environment answers it ahead of time.
+ask_officer_root() {
+  local default="${USER_HOME}/officerdev" answer
+
+  if [[ -n "${OFFICER_ROOT:-}" ]]; then
+    answer="$OFFICER_ROOT"
+  else
+    echo ""
+    info "Where should Officer be installed?"
+    echo "     One directory holding the app, its data, the item store and any"
+    echo "     containers the app store provisions — so it can be moved, backed"
+    echo "     up or deleted as a unit."
+    echo ""
+    if ! read -rp "  Path [${default}]: " answer; then
+      echo ""
+      fail "No answer. Set OFFICER_ROOT=<path> to answer this ahead of time."
+    fi
+    answer="${answer:-$default}"
+  fi
+
+  # A leading ~ arrives as a literal when it comes from a read or an environment
+  # variable — nothing expands it there — and would create a directory named "~".
+  answer="${answer/#\~/$USER_HOME}"
+
+  [[ "$answer" == /* ]] || fail "That needs to be an absolute path, starting with / — got '${answer}'"
+
+  OFFICER_ROOT="${answer%/}"
+}
+
 # Run a block as the created user (login shell, inherits HOME)
 as_user() {
   sudo -u "$USERNAME" -i bash -c "$1"
diff --git a/scripts/setup/machine-setup/machine-setup.sh b/scripts/setup/machine-setup/machine-setup.sh
index 2dab1855..c62ca90d 100755
--- a/scripts/setup/machine-setup/machine-setup.sh
+++ b/scripts/setup/machine-setup/machine-setup.sh
@@ -78,6 +78,13 @@ fi
 
 USER_HOME="/home/$USERNAME"
 
+ask_officer_root
+if [[ -d "$OFFICER_ROOT" ]]; then
+  info "Officer:  ${OFFICER_ROOT} (exists already)"
+else
+  info "Officer:  ${OFFICER_ROOT}"
+fi
+
 # Always, and outside any step: everything below reads this index — core utils,
 # the fastfetch PPA, the Docker repo — and `step` skips a step whose name is
 # already in the progress file. With the refresh inside one of those, a resumed
@@ -579,6 +586,7 @@ echo "    System:     $OS_NAME ($ARCH)"
 echo "    Role:       $MACHINE_ROLE"
 echo "    User:       $USERNAME"
 echo "    Home:       $USER_HOME"
+echo "    Officer:    $OFFICER_ROOT"
 [[ -n "${TS_IP:-}" && "$TS_IP" != "unknown" ]] && echo "    Tailscale:  $TS_IP"
 echo ""