diff --git a/AGENTS.md b/AGENTS.md
index 3bd212ef..0b136ba4 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -4,10 +4,16 @@
 
 ### Shell Scripts
 
-- Max 30 lines per file
-- Use `set -euo pipefail` for scripts
+- Executable scripts (`scripts/*.sh`) start with `set -euo pipefail`
+- Sourced files must NOT set shell options: `lib/*.sh` and everything under
+  `DreamcoderShell/.config/shell/` run inside the caller's shell, and `errexit`/`nounset`
+  there closes an interactive terminal on the first failing command
+- Shell fragments loaded by interactive shells (aliases, small functions) stay short;
+  scripts and libraries have one purpose per file and functions that fit on a screen
 - Quote all variables: `"${var}"`
 - Use `[[ ]]` instead of `[ ]` for tests
+- Pass values to inline Python or other interpreters through arguments, never by
+  interpolating them into source text
 
 ### Modularity
 
diff --git a/lib/ml4w.sh b/lib/ml4w.sh
index 23b6e962..897b1fc4 100644
--- a/lib/ml4w.sh
+++ b/lib/ml4w.sh
@@ -26,15 +26,33 @@ waybar_is_ml4w_managed() {
     return 1
 }
 
+# A config path is ML4W-managed when it is a symlink itself, or when it resolves
+# into the ML4W dotfiles root. ML4W 2.16 links whole app directories
+# (~/.config/rofi -> ~/.mydotfiles/...), so the files inside are regular files from
+# the link's point of view while ML4W still owns them. ML4W_DOTFILES_DIR relocates
+# the root for non-default installs.
+path_is_ml4w_managed() {
+    local path="$1" real root="${ML4W_DOTFILES_DIR:-${HOME}/.mydotfiles}"
+    [[ -e "${path}" ]] || return 1
+    [[ -L "${path}" ]] && return 0
+    real="$(readlink -f -- "${path}")" || return 1
+    [[ "${real}" == "${root}/"* ]]
+}
+
 # Hyprland colour files (colors.lua / colors.conf) carry Dreamcoder colours when
 # they are a symlink into a Dreamcoder variant, or a regular file byte-identical
 # to one of the DreamcoderThemes hypr-colors-* variants. Regular files are the
 # supported layout: ML4W 2.16 ships them as regular files and the theme sync
 # writes through whatever sits at the path (it only flips existing symlinks).
+# True when the path is a symlink whose target name carries "dreamcoder".
+_is_dreamcoder_symlink() {
+    [[ -L "$1" && "$(readlink "$1")" == *dreamcoder* ]]
+}
+
 hypr_colors_is_dreamcoder() {
     local path="$1" variant
     [[ -e "${path}" ]] || return 1
-    [[ -L "${path}" && "$(readlink "${path}")" == *dreamcoder* ]] && return 0
+    _is_dreamcoder_symlink "${path}" && return 0
     for variant in "${DREAMCODER_DOTS_DIR}"/DreamcoderThemes/dreamcoder/hypr-colors-*."${path##*.}"; do
         [[ -f "${variant}" ]] && cmp -s "${path}" "${variant}" && return 0
     done
@@ -48,7 +66,7 @@ hypr_colors_is_dreamcoder() {
 waybar_colors_is_dreamcoder() {
     local path="$1"
     [[ -e "${path}" ]] || return 1
-    [[ -L "${path}" && "$(readlink "${path}")" == *dreamcoder* ]] && return 0
+    _is_dreamcoder_symlink "${path}" && return 0
     [[ -L "${path}" ]] && return 1
     head -n 5 "${path}" | grep -q 'Generated by Dreamcoder sync'
 }
diff --git a/scripts/verify-ml4w-setup.sh b/scripts/verify-ml4w-setup.sh
index 8359962a..9e1815d3 100755
--- a/scripts/verify-ml4w-setup.sh
+++ b/scripts/verify-ml4w-setup.sh
@@ -80,22 +80,24 @@ echo ""
 # ── 1. System checks ═════════════════════════════════════════════════════════
 title "1. System"
 
-if command -v hyprctl >/dev/null; then
-  if hyprctl monitors -j 2>/dev/null | jq -e 'length > 0' >/dev/null 2>&1; then
-    ok "Hyprland is running"
-  else
-    fail "Hyprland is not running (no monitors detected)"
-  fi
-else
-  fail "hyprctl not found — Hyprland not installed?"
-fi
-
+have_jq=0
 if command -v jq >/dev/null; then
   ok "jq is installed"
+  have_jq=1
 else
   fail "jq is not installed"
 fi
 
+if ! command -v hyprctl >/dev/null; then
+  fail "hyprctl not found — Hyprland not installed?"
+elif ((!have_jq)); then
+  warn "Hyprland running check skipped (needs jq)"
+elif hyprctl monitors -j 2>/dev/null | jq -e 'length > 0' >/dev/null 2>&1; then
+  ok "Hyprland is running"
+else
+  fail "Hyprland is not running (no monitors detected)"
+fi
+
 HYPR_VERSION=""
 if command -v hyprctl >/dev/null; then
   HYPR_VERSION="$(hyprctl version 2>/dev/null | head -1 | grep -oP 'Hyprland \K[^ ]+' || echo "unknown")"
@@ -114,11 +116,10 @@ SYMLINKS=(
 for entry in "${SYMLINKS[@]}"; do
   path="${entry%%:*}"
   label="${entry#*:}"
-  if [[ -L "$path" ]]; then
-    target=$(readlink "$path")
-    ok "${label} (→ ${target})"
+  if path_is_ml4w_managed "$path"; then
+    ok "${label} (→ $(readlink -f -- "$path"))"
   elif [[ -f "$path" ]]; then
-    warn "${label} — regular file, not symlink"
+    warn "${label} — regular file outside the ML4W dotfiles"
   else
     fail "${label} — NOT FOUND"
   fi
@@ -160,29 +161,22 @@ else
   fail "waybar/colors.css is missing"
 fi
 
-# Wlogout → waybar
-if [[ -L "${HOME}/.config/wlogout/colors.css" ]]; then
-  target=$(readlink "${HOME}/.config/wlogout/colors.css")
-  if [[ "$target" == *"waybar/colors.css" ]]; then
-    ok "wlogout/colors.css → waybar (shared)"
-  else
-    warn "wlogout/colors.css → ${target}"
-  fi
-else
-  fail "wlogout/colors.css is not a symlink"
-fi
-
-# Swaync → waybar
-if [[ -L "${HOME}/.config/swaync/colors.css" ]]; then
-  target=$(readlink "${HOME}/.config/swaync/colors.css")
-  if [[ "$target" == *"waybar/colors.css" ]]; then
-    ok "swaync/colors.css → waybar (shared)"
+# Wlogout and Swaync share Waybar's colours through a symlink.
+check_shared_waybar_colors() {
+  local app="$1" link="${HOME}/.config/${1}/colors.css" target
+  if [[ -L "$link" ]]; then
+    target=$(readlink "$link")
+    if [[ "$target" == *"waybar/colors.css" ]]; then
+      ok "${app}/colors.css → waybar (shared)"
+    else
+      warn "${app}/colors.css → ${target}"
+    fi
   else
-    warn "swaync/colors.css → ${target}"
+    fail "${app}/colors.css is not a symlink"
   fi
-else
-  fail "swaync/colors.css is not a symlink"
-fi
+}
+check_shared_waybar_colors wlogout
+check_shared_waybar_colors swaync
 
 # Hyprland colors.lua / colors.conf: a Dreamcoder symlink or a managed regular
 # file with Dreamcoder content (ML4W 2.16 ships regular files; the sync writes
@@ -278,21 +272,22 @@ fi
 # ── 7. ML4W profile ═══════════════════════════════════════════════════════
 title "7. ML4W profile"
 
-if [[ -n "${PROFILE_NAME}" ]]; then
-  PROFILE_FILE="${DREAMCODER_DOTS_DIR}/DreamcoderProfiles/dreamcoder/${PROFILE_NAME}.json"
-else
+if [[ -z "${PROFILE_NAME}" ]]; then
   # Auto-detect
   HOSTNAME="$(hostname -s 2>/dev/null || echo "unknown")"
   case "$(echo "${HOSTNAME}" | tr '[:upper:]' '[:lower:]')" in
   *asus* | *vivobook*) PROFILE_NAME="asus-vivobook15" ;;
   *) PROFILE_NAME="default" ;;
   esac
-  PROFILE_FILE="${DREAMCODER_DOTS_DIR}/DreamcoderProfiles/dreamcoder/${PROFILE_NAME}.json"
   info "Auto-detected profile: ${PROFILE_NAME}"
 fi
+PROFILES_DIR="${DREAMCODER_DOTS_DIR}/DreamcoderProfiles/dreamcoder"
+PROFILE_FILE="${PROFILES_DIR}/${PROFILE_NAME}.json"
 
 if [[ -f "$PROFILE_FILE" ]]; then
-  if jq empty "$PROFILE_FILE" 2>/dev/null; then
+  if ((!have_jq)); then
+    warn "Profile ${PROFILE_NAME}.json JSON check skipped (needs jq)"
+  elif jq empty "$PROFILE_FILE" 2>/dev/null; then
     ok "Profile ${PROFILE_NAME}.json is valid JSON"
   else
     fail "Profile ${PROFILE_NAME}.json is INVALID JSON"
@@ -302,22 +297,31 @@ else
 fi
 
 # Schema validation
-SCHEMA_FILE="${DREAMCODER_DOTS_DIR}/DreamcoderProfiles/dreamcoder/profile.schema.json"
+SCHEMA_FILE="${PROFILES_DIR}/profile.schema.json"
 if [[ -f "$SCHEMA_FILE" ]]; then
   ok "Schema file exists"
   if command -v python3 >/dev/null && python3 -c "import jsonschema" 2>/dev/null; then
-    if python3 -c "
-import json, sys
-with open('${SCHEMA_FILE}') as f: schema = json.load(f)
-with open('${PROFILE_FILE}') as f: profile = json.load(f)
+    # Paths travel through argv: interpolating them into Python source breaks on a
+    # quote and would let a crafted path run code.
+    if python3 - "$SCHEMA_FILE" "$PROFILE_FILE" 2>/dev/null <<'PY'
+import json
+import sys
+
 import jsonschema
+
+with open(sys.argv[1]) as f:
+    schema = json.load(f)
+with open(sys.argv[2]) as f:
+    profile = json.load(f)
 jsonschema.validate(instance=profile, schema=schema)
-print('OK')
-" 2>/dev/null; then
+PY
+    then
       ok "Profile matches schema"
     else
       warn "Profile does NOT match schema"
     fi
+  else
+    warn "Schema validation skipped (python3 with jsonschema not available)"
   fi
 else
   warn "Schema file not found"
diff --git a/tests/ml4w/ml4w_managed.bats b/tests/ml4w/ml4w_managed.bats
index e78430d3..472f8703 100644
--- a/tests/ml4w/ml4w_managed.bats
+++ b/tests/ml4w/ml4w_managed.bats
@@ -200,3 +200,53 @@ load_ml4w_lib() {
   run waybar_colors_is_dreamcoder "${HOME}/.config/waybar/colors.css"
   [ "$status" -ne 0 ]
 }
+
+# ── path_is_ml4w_managed ─────────────────────────────────────────────────────
+# ML4W 2.16 links whole app directories (~/.config/rofi -> ~/.mydotfiles/...), so
+# the files inside are regular files from the link's point of view while still
+# being owned by ML4W. Ownership therefore follows where the path resolves to.
+
+@test "ml4w lib: a file inside a directory symlinked into the ML4W dotfiles is managed" {
+  mkdir -p "${HOME}/.config" "${HOME}/.mydotfiles/com.ml4w.dotfiles/.config/rofi"
+  : >"${HOME}/.mydotfiles/com.ml4w.dotfiles/.config/rofi/config.rasi"
+  ln -s "${HOME}/.mydotfiles/com.ml4w.dotfiles/.config/rofi" "${HOME}/.config/rofi"
+
+  load_ml4w_lib
+  run path_is_ml4w_managed "${HOME}/.config/rofi/config.rasi"
+  [ "$status" -eq 0 ]
+}
+
+@test "ml4w lib: a symlinked file is managed" {
+  mkdir -p "${HOME}/.config/swaync" "${HOME}/.mydotfiles/x"
+  : >"${HOME}/.mydotfiles/x/config.json"
+  ln -s "${HOME}/.mydotfiles/x/config.json" "${HOME}/.config/swaync/config.json"
+
+  load_ml4w_lib
+  run path_is_ml4w_managed "${HOME}/.config/swaync/config.json"
+  [ "$status" -eq 0 ]
+}
+
+@test "ml4w lib: a plain regular file outside the ML4W dotfiles is not managed" {
+  mkdir -p "${HOME}/.config/wlogout"
+  : >"${HOME}/.config/wlogout/layout"
+
+  load_ml4w_lib
+  run path_is_ml4w_managed "${HOME}/.config/wlogout/layout"
+  [ "$status" -ne 0 ]
+}
+
+@test "ml4w lib: a missing path is not managed" {
+  load_ml4w_lib
+  run path_is_ml4w_managed "${HOME}/.config/rofi/config.rasi"
+  [ "$status" -ne 0 ]
+}
+
+@test "ml4w lib: ML4W_DOTFILES_DIR relocates the dotfiles root" {
+  mkdir -p "${HOME}/elsewhere/rofi" "${HOME}/.config"
+  : >"${HOME}/elsewhere/rofi/config.rasi"
+  ln -s "${HOME}/elsewhere/rofi" "${HOME}/.config/rofi"
+
+  load_ml4w_lib
+  ML4W_DOTFILES_DIR="${HOME}/elsewhere" run path_is_ml4w_managed "${HOME}/.config/rofi/config.rasi"
+  [ "$status" -eq 0 ]
+}
diff --git a/tests/ml4w/verify_setup.bats b/tests/ml4w/verify_setup.bats
new file mode 100644
index 00000000..31f532bd
--- /dev/null
+++ b/tests/ml4w/verify_setup.bats
@@ -0,0 +1,65 @@
+# ============================================================================
+# BATS tests: scripts/verify-ml4w-setup.sh robustness
+# ============================================================================
+# The script used to interpolate file paths into inline Python source, so a path
+# with an apostrophe broke schema validation (and a crafted one could inject
+# code); paths now travel through sys.argv. A missing jsonschema also skipped the
+# check without saying so.
+
+load '../helpers/setup'
+
+# tests/helpers/setup.bash points HOME at a temp dir, which hides user-site Python
+# packages (jsonschema often lives there). Keep the invoking user's package base so the
+# schema check really runs instead of being skipped.
+use_real_python_userbase() {
+  local real_home
+  real_home="$(getent passwd "$(id -u)" | cut -d: -f6)"
+  export PYTHONUSERBASE="${real_home}/.local"
+}
+
+# A throwaway dots tree whose directory name contains an apostrophe.
+make_dots_tree() {
+  DOTS="${TEST_TEMP_HOME}/dots'tree"
+  mkdir -p "${DOTS}/lib" "${DOTS}/DreamcoderProfiles/dreamcoder"
+  cp "${DREAMCODER_DOTS_DIR}/lib/"*.sh "${DOTS}/lib/"
+  cp "${DREAMCODER_DOTS_DIR}/DreamcoderProfiles/dreamcoder/default.json" \
+     "${DREAMCODER_DOTS_DIR}/DreamcoderProfiles/dreamcoder/profile.schema.json" \
+     "${DOTS}/DreamcoderProfiles/dreamcoder/"
+}
+
+run_verify() {
+  DREAMCODER_DOTS_DIR="${DOTS}" run bash "${BATS_TEST_DIRNAME}/../../scripts/verify-ml4w-setup.sh" \
+    --profile default
+}
+
+@test "verify-ml4w-setup: schema validation works when the dots path contains an apostrophe" {
+  use_real_python_userbase
+  python3 -c 'import jsonschema' 2>/dev/null || skip "python jsonschema not installed"
+  command -v jq >/dev/null || skip "jq not installed"
+  make_dots_tree
+  run_verify
+  [[ "$output" == *"Profile matches schema"* ]]
+}
+
+@test "verify-ml4w-setup: says so when schema validation is skipped for lack of jsonschema" {
+  make_dots_tree
+  # A python3 without jsonschema: a shim earlier in PATH.
+  mkdir -p "${TEST_TEMP_HOME}/bin"
+  printf '#!/bin/sh\nexit 1\n' >"${TEST_TEMP_HOME}/bin/python3"
+  chmod +x "${TEST_TEMP_HOME}/bin/python3"
+  PATH="${TEST_TEMP_HOME}/bin:${PATH}" run_verify
+  [[ "$output" == *"Schema validation skipped"* ]]
+}
+
+@test "verify-ml4w-setup: a missing jq is reported as skipped, not as invalid JSON" {
+  make_dots_tree
+  # PATH with every tool except jq: symlink the basics into an empty bin dir.
+  mkdir -p "${TEST_TEMP_HOME}/nojq"
+  for tool in bash env dirname basename cat grep sed awk tr cut head tail sort uniq date git python3 readlink; do
+    src="$(command -v "$tool" 2>/dev/null)" && ln -sf "$src" "${TEST_TEMP_HOME}/nojq/$tool"
+  done
+  PATH="${TEST_TEMP_HOME}/nojq" run_verify
+  [[ "$output" == *"jq is not installed"* ]]
+  [[ "$output" == *"JSON check skipped (needs jq)"* ]]
+  [[ "$output" != *"INVALID JSON"* ]]
+}