diff --git a/bin/omarchy-install-browser b/bin/omarchy-install-browser
index f71c7c98..4593bc72 100755
--- a/bin/omarchy-install-browser
+++ b/bin/omarchy-install-browser
@@ -6,9 +6,10 @@
 
 set -e
 
-setup_policy_directory() {
-  sudo mkdir -p "$1"
-  sudo chmod a+rw "$1"
+source "$OMARCHY_PATH/install/helpers/browser-policy.sh"
+
+setup_chromium_policy_directory() {
+  browser_policy_setup_dir "$1"
 }
 
 announce_browser_installed() {
@@ -23,13 +24,6 @@ copy_chromium_flags() {
   omarchy-install-chromium-ytdlp
 }
 
-setup_firefox_preferences() {
-  local distribution_dir="$1"
-
-  setup_policy_directory "$distribution_dir"
-  sudo cp -f "$OMARCHY_PATH/default/firefox/policies.json" "$distribution_dir/policies.json"
-}
-
 setup_firefox_wayland() {
   mkdir -p ~/.config/environment.d
   echo "MOZ_ENABLE_WAYLAND=1" > ~/.config/environment.d/omarchy-firefox-wayland.conf
@@ -40,7 +34,7 @@ chromium)
   echo "Installing Chromium..."
   omarchy-pkg-add chromium
 
-  setup_policy_directory /etc/chromium/policies/managed
+  setup_chromium_policy_directory /etc/chromium/policies/managed
   copy_chromium_flags ~/.config/chromium-flags.conf
   omarchy-theme-set-browser
   announce_browser_installed "Chromium"
@@ -49,7 +43,7 @@ chrome)
   echo "Installing Chrome..."
   omarchy-pkg-aur-add google-chrome || exit 1
 
-  setup_policy_directory /etc/opt/chrome/policies/managed
+  setup_chromium_policy_directory /etc/opt/chrome/policies/managed
   copy_chromium_flags ~/.config/chrome-flags.conf
   omarchy-theme-set-browser
   announce_browser_installed "Chrome"
@@ -58,7 +52,7 @@ edge)
   echo "Installing Edge..."
   omarchy-pkg-aur-add microsoft-edge-stable-bin || exit 1
 
-  setup_policy_directory /etc/opt/edge/policies/managed
+  setup_chromium_policy_directory /etc/opt/edge/policies/managed
   copy_chromium_flags ~/.config/microsoft-edge-stable-flags.conf
   omarchy-theme-set-browser
   announce_browser_installed "Edge"
@@ -67,7 +61,7 @@ brave)
   echo "Installing Brave..."
   omarchy-pkg-aur-add brave-bin || exit 1
 
-  setup_policy_directory /etc/brave/policies/managed
+  setup_chromium_policy_directory /etc/brave/policies/managed
   copy_chromium_flags ~/.config/brave-flags.conf
   omarchy-theme-set-browser
   announce_browser_installed "Brave"
@@ -76,7 +70,7 @@ brave-origin)
   echo "Installing Brave Origin..."
   omarchy-pkg-aur-add brave-origin-bin || exit 1
 
-  setup_policy_directory /etc/brave/policies/managed
+  setup_chromium_policy_directory /etc/brave/policies/managed
   copy_chromium_flags ~/.config/brave-origin-flags.conf
   omarchy-theme-set-browser
   announce_browser_installed "Brave Origin"
@@ -85,7 +79,7 @@ firefox)
   echo "Installing Firefox..."
   omarchy-pkg-add firefox || exit 1
 
-  setup_firefox_preferences /usr/lib/firefox/distribution
+  browser_policy_setup_firefox_distribution /usr/lib/firefox/distribution
   setup_firefox_wayland
   announce_browser_installed "Firefox"
   ;;
@@ -93,7 +87,7 @@ zen)
   echo "Installing Zen..."
   omarchy-pkg-aur-add zen-browser-bin || exit 1
 
-  setup_firefox_preferences /opt/zen-browser/distribution
+  browser_policy_setup_firefox_distribution /opt/zen-browser/distribution
   setup_firefox_wayland
   announce_browser_installed "Zen"
   ;;
diff --git a/bin/omarchy-provision-owner b/bin/omarchy-provision-owner
index c27de22c..0db99f2e 100755
--- a/bin/omarchy-provision-owner
+++ b/bin/omarchy-provision-owner
@@ -742,6 +742,12 @@ create_user() {
   # for specific commands), and a duplicate grant is harmless.
   echo "%wheel ALL=(ALL:ALL) ALL" >/etc/sudoers.d/00-omarchy-wheel
   chmod 440 /etc/sudoers.d/00-omarchy-wheel
+
+  source "$OMARCHY_PATH/install/helpers/browser-policy.sh"
+  for dir in "${BROWSER_POLICY_MANAGED_DIRS[@]}"; do
+    [[ -d $dir || -L $dir ]] || continue
+    browser_policy_setup_dir "$dir"
+  done
 }
 
 install_authorized_keys() {
diff --git a/bin/omarchy-theme-set-browser b/bin/omarchy-theme-set-browser
index 4dd7592f..612e586f 100755
--- a/bin/omarchy-theme-set-browser
+++ b/bin/omarchy-theme-set-browser
@@ -3,23 +3,15 @@
 # omarchy:summary=Apply the current theme color to Chromium, Chrome, Edge, and Brave
 # omarchy:hidden=true
 
+source "$OMARCHY_PATH/install/helpers/browser-policy.sh"
+
 CHROMIUM_THEME=$HOME/.local/state/omarchy/current/theme/chromium.theme
+THEME_HEX_COLOR=$BROWSER_POLICY_DEFAULT_COLOR
 
 if [[ -f $CHROMIUM_THEME ]]; then
-  THEME_RGB_COLOR=$(<$CHROMIUM_THEME)
-  THEME_HEX_COLOR=$(printf '#%02x%02x%02x' ${THEME_RGB_COLOR//,/ })
-else
-  # Use a default, neutral grey if theme doesn't have a color
-  THEME_HEX_COLOR="#1c2027"
+  THEME_HEX_COLOR=$(browser_policy_theme_hex "$(<$CHROMIUM_THEME)")
 fi
 
-set_browser_policy() {
-  local policy_dir="$1"
-
-  [[ -d $policy_dir ]] || return
-  echo "{\"BrowserThemeColor\": \"$THEME_HEX_COLOR\", \"BrowserColorScheme\": \"device\"}" | tee "$policy_dir/color.json" >/dev/null
-}
-
 refresh_running_browser() {
   local process="$1"
   local command="$2"
@@ -30,17 +22,15 @@ refresh_running_browser() {
   fi
 }
 
-set_browser_policy /etc/chromium/policies/managed
+failed=0
+omarchy-theme-set-browser-policy "${THEME_HEX_COLOR#\#}" || failed=1
+
 refresh_running_browser chromium chromium
-
-set_browser_policy /etc/opt/chrome/policies/managed
 refresh_running_browser chrome google-chrome-stable || refresh_running_browser chrome google-chrome
-
-set_browser_policy /etc/opt/edge/policies/managed
 refresh_running_browser msedge microsoft-edge-stable
-
-set_browser_policy /etc/brave/policies/managed
 refresh_running_browser brave brave
 # Match on the binary path: the running process is named plain "brave", and a
 # bare -f brave-origin pattern would also match the installer's own terminal.
 refresh_running_browser /opt/brave-origin-bin/ brave-origin -f
+
+exit "$failed"
diff --git a/bin/omarchy-theme-set-browser-policy b/bin/omarchy-theme-set-browser-policy
new file mode 100755
index 00000000..6f628f9b
--- /dev/null
+++ b/bin/omarchy-theme-set-browser-policy
@@ -0,0 +1,118 @@
+#!/bin/bash
+
+# omarchy:summary=Write the current theme color into the browser policy directories
+# omarchy:args=<rrggbb>
+# omarchy:hidden=true
+
+set -euo pipefail
+
+# Whenever this runs as root — invoked directly through the passwordless
+# sudoers rule, or re-execed by require_root below — sudo's secure_path decides
+# where a bare helper resolves, and a dev link (etc/sudoers.d/omarchy-dev-path)
+# prepends a user-writable checkout bin/ to it. Every helper this script calls
+# by bare name (printf's builtin aside: install, mktemp, rm) is a system tool,
+# never an omarchy-* command, so pin PATH to trusted system directories and keep
+# root from resolving one out of that checkout. The unprivileged wrapper phase
+# keeps the caller's PATH so it can still find sudo/pkexec.
+if (( EUID == 0 )); then
+  export PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/sbin:/bin:/sbin
+fi
+
+# Enterprise policy trust roots. The list is fixed here rather than taken from
+# the caller: the caller chooses a color, never a path.
+POLICY_DIRS=(
+  /etc/chromium/policies/managed
+  /etc/opt/chrome/policies/managed
+  /etc/opt/edge/policies/managed
+  /etc/brave/policies/managed
+)
+
+# The path etc/sudoers.d/omarchy-theme-browser names. The privileged half always
+# runs from there rather than from whichever copy was invoked, so the rule
+# matches even where $OMARCHY_PATH points at a checkout.
+PACKAGED_PATH=/usr/bin/omarchy-theme-set-browser-policy
+
+usage() {
+  echo "Usage: omarchy-theme-set-browser-policy <rrggbb>" >&2
+}
+
+if (( $# != 1 )); then
+  usage
+  exit 1
+fi
+
+color="$1"
+
+# Six lowercase hex digits is the whole of what this accepts. The leading "#"
+# is added when the JSON is written rather than passed in: "#" opens a comment
+# in sudoers, and keeping it out of argv lets the sudoers rule spell the
+# argument as a plain six-character glob.
+if [[ ! $color =~ ^[0-9a-f]{6}$ ]]; then
+  echo "omarchy-theme-set-browser-policy: expected six lowercase hex digits, got '$color'" >&2
+  exit 1
+fi
+
+# True when sudo would run this exact command without stopping for a password.
+# `sudo -l` on its own reports whether a command is permitted, which the blanket
+# %wheel rule answers yes to for everything; the long listing prints the matched
+# entry's tags, so !authenticate is the grant in
+# etc/sudoers.d/omarchy-theme-browser and nothing else. Listing runs nothing
+# and, under -n, prompts for nothing.
+sudo_grants_passwordless() {
+  sudo -n -l -l "$PACKAGED_PATH" "$@" 2>/dev/null | grep -q '!authenticate'
+}
+
+require_root() {
+  if (( EUID == 0 )); then
+    return
+  elif [[ -t 0 ]] || sudo_grants_passwordless "$@"; then
+    exec sudo "$PACKAGED_PATH" "$@"
+  else
+    exec pkexec "$PACKAGED_PATH" "$@"
+  fi
+}
+
+require_root "$color"
+
+failed=0
+staged=""
+cleanup() {
+  [[ -n $staged ]] && rm -f "$staged"
+}
+trap cleanup EXIT
+
+for policy_dir in "${POLICY_DIRS[@]}"; do
+  # Only browsers Omarchy has installed have a policy directory. Creating one
+  # here would hand a browser a managed-policy root it does not otherwise have.
+  [[ -d $policy_dir && ! -L $policy_dir ]] || continue
+
+  dest=$policy_dir/color.json
+  staged=$(mktemp) || {
+    failed=1
+    continue
+  }
+  printf '{"BrowserThemeColor": "#%s", "BrowserColorScheme": "device"}\n' "$color" >"$staged"
+
+  if [[ -L $dest || -d $dest ]]; then
+    if ! rm -rf -- "$dest"; then
+      rm -f "$staged"
+      staged=""
+      echo "omarchy-theme-set-browser-policy: cannot replace $dest" >&2
+      failed=1
+      continue
+    fi
+  fi
+
+  if ! install -m 0644 -o root -g root -T "$staged" "$dest"; then
+    rm -f "$staged"
+    staged=""
+    echo "omarchy-theme-set-browser-policy: cannot write $dest" >&2
+    failed=1
+    continue
+  fi
+
+  rm -f "$staged"
+  staged=""
+done
+
+exit "$failed"
diff --git a/bin/omarchy-upgrade-to-quattro b/bin/omarchy-upgrade-to-quattro
index e28da697..32ea6465 100755
--- a/bin/omarchy-upgrade-to-quattro
+++ b/bin/omarchy-upgrade-to-quattro
@@ -1312,7 +1312,21 @@ apply_system_transition() {
     /usr/share/icons/Yaru/scalable/actions/go-next-symbolic.svg
   as_root gtk-update-icon-cache /usr/share/icons/Yaru >/dev/null 2>&1 || true
 
-  as_root install -d -m 0777 /etc/chromium/policies/managed
+  local browser_policy_helper=/usr/share/omarchy/install/helpers/browser-policy.sh
+  if ! as_root test -f "$browser_policy_helper"; then
+    warn "$browser_policy_helper is unavailable; Chromium policy directories were not hardened."
+  else
+    as_root env OMARCHY_PATH=/usr/share/omarchy \
+      bash -euo pipefail -c '
+        source "$OMARCHY_PATH/install/helpers/browser-policy.sh"
+        browser_policy_setup_dir /etc/chromium/policies/managed
+        for dir in "${BROWSER_POLICY_MANAGED_DIRS[@]}"; do
+          [[ $dir == "/etc/chromium/policies/managed" ]] && continue
+          [[ -d $dir || -L $dir ]] || continue
+          browser_policy_setup_dir "$dir"
+        done
+      '
+  fi
   as_root install -d -m 0755 /usr/lib/chromium
   printf '%s\n' '{"browser":{"theme":{"color_scheme":0,"color_scheme2":0}}}' | \
     as_root tee /usr/lib/chromium/initial_preferences >/dev/null
@@ -2306,6 +2320,11 @@ refresh_current_theme_after_upgrade() {
   # hooks because one of them runs `hyprctl reload`. Still poke terminal
   # emulators so the active upgrade terminal picks up generated theme files.
   run_as_user_omarchy omarchy-restart-terminal >/dev/null 2>&1 || true
+
+  # apply_system_transition purged user-owned color.json. Headless theme-set
+  # skipped omarchy-theme-set-browser, so rewrite the colour here.
+  run_as_user_omarchy omarchy-theme-set-browser >/dev/null 2>&1 ||
+    warn "Could not apply browser theme colour. Run 'omarchy theme set \"$theme_name\"' after reboot if Chromium's theme looks stale."
 }
 
 # Everything below mutates the system, so a non-zero exit from here on leaves a
diff --git a/etc/sudoers.d/omarchy-theme-browser b/etc/sudoers.d/omarchy-theme-browser
new file mode 100644
index 00000000..853d2412
--- /dev/null
+++ b/etc/sudoers.d/omarchy-theme-browser
@@ -0,0 +1,8 @@
+# Theme switching is a menu action with no terminal to carry a password prompt,
+# and it repaints the browser accent on every switch, so this one write must not
+# stop for a password. The argument is spelled out as six hex digits rather than
+# a wildcard: the grant covers a color and nothing else, and sudoers matches a
+# command's arguments exactly, so it cannot be stretched into extra ones. The
+# helper revalidates the same shape, since the terminal path does not come
+# through this rule.
+%wheel ALL=(root) NOPASSWD: /usr/bin/omarchy-theme-set-browser-policy [0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]
diff --git a/install/config/all.sh b/install/config/all.sh
index 91256dc7..d8c7d9bb 100644
--- a/install/config/all.sh
+++ b/install/config/all.sh
@@ -1,4 +1,5 @@
 run_logged "$OMARCHY_INSTALL/config/theme-system.sh"
+run_logged "$OMARCHY_INSTALL/config/browser-policy.sh"
 run_logged "$OMARCHY_INSTALL/config/increase-lockout-limit.sh"
 run_logged "$OMARCHY_INSTALL/config/lockscreen-pam.sh"
 run_logged "$OMARCHY_INSTALL/config/fix-powerprofilesctl-shebang.sh"
diff --git a/install/config/browser-policy.sh b/install/config/browser-policy.sh
new file mode 100644
index 00000000..fd802c66
--- /dev/null
+++ b/install/config/browser-policy.sh
@@ -0,0 +1,2 @@
+source "$OMARCHY_PATH/install/helpers/browser-policy.sh"
+browser_policy_setup_dir /etc/chromium/policies/managed
diff --git a/install/config/theme-system.sh b/install/config/theme-system.sh
index 2902e1cd..83db0e15 100644
--- a/install/config/theme-system.sh
+++ b/install/config/theme-system.sh
@@ -6,10 +6,6 @@ ln -snf /usr/share/icons/Adwaita/symbolic/actions/go-next-symbolic.svg \
           /usr/share/icons/Yaru/scalable/actions/go-next-symbolic.svg
 gtk-update-icon-cache /usr/share/icons/Yaru &>/dev/null || true
 
-# Chromium policy directory for theme
-mkdir -p /etc/chromium/policies/managed
-chmod a+rw /etc/chromium/policies/managed
-
 # Default Chromium to follow system appearance ("device") instead of dark
 mkdir -p /usr/lib/chromium
 echo '{"browser":{"theme":{"color_scheme":0,"color_scheme2":0}}}' > \
diff --git a/install/helpers/as-root.sh b/install/helpers/as-root.sh
new file mode 100644
index 00000000..005ae351
--- /dev/null
+++ b/install/helpers/as-root.sh
@@ -0,0 +1,7 @@
+as_root() {
+  if (( EUID == 0 )); then
+    "$@"
+  else
+    sudo "$@"
+  fi
+}
diff --git a/install/helpers/browser-policy.sh b/install/helpers/browser-policy.sh
new file mode 100644
index 00000000..c2c93d8e
--- /dev/null
+++ b/install/helpers/browser-policy.sh
@@ -0,0 +1,168 @@
+# Chromium-family machine policy is mandatory for every profile. Directories
+# stay 0755 root:root; omarchy-theme-set-browser-policy is the privileged
+# write for color.json.
+
+source "$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)/as-root.sh"
+
+BROWSER_POLICY_MANAGED_DIRS=(
+  /etc/chromium/policies/managed
+  /etc/opt/chrome/policies/managed
+  /etc/opt/edge/policies/managed
+  /etc/brave/policies/managed
+)
+
+# Ancestors of the managed dirs, shortest first. A writable or attacker-owned
+# parent can rename the leaf aside; install -d follows a planted symlink.
+BROWSER_POLICY_PARENT_DIRS=(
+  /etc/chromium
+  /etc/chromium/policies
+  /etc/opt/chrome
+  /etc/opt/chrome/policies
+  /etc/opt/edge
+  /etc/opt/edge/policies
+  /etc/brave
+  /etc/brave/policies
+)
+
+BROWSER_POLICY_FIREFOX_DIRS=(
+  /usr/lib/firefox/distribution
+  /opt/zen-browser/distribution
+)
+
+BROWSER_POLICY_DEFAULT_COLOR="#1c2027"
+
+browser_policy_purge_dir() {
+  local dir=$1
+
+  as_root find "$dir" -mindepth 1 -maxdepth 1 ! -user root -exec rm -rf -- {} +
+}
+
+browser_policy_parent_hardened() {
+  local dir=$1
+
+  [[ -d $dir && ! -L $dir ]] || return 1
+  [[ $(stat -c '%a' "$dir") == "755" ]] || return 1
+  [[ $(stat -c '%U' "$dir") == "root" ]] || return 1
+}
+
+browser_policy_dir_hardened() {
+  browser_policy_parent_hardened "$1"
+}
+
+browser_policy_parents_hardened() {
+  local dir=$1
+  local parent
+
+  for parent in "${BROWSER_POLICY_PARENT_DIRS[@]}"; do
+    [[ $dir == "$parent"/* ]] || continue
+    [[ -e $parent || -L $parent ]] || continue
+    browser_policy_parent_hardened "$parent" || return 1
+  done
+}
+
+browser_policy_setup_parent() {
+  local dir=$1
+
+  if [[ -L $dir || ( -e $dir && ! -d $dir ) ]]; then
+    as_root rm -rf -- "$dir"
+  fi
+  as_root install -d -m 0755 -o root -g root "$dir"
+}
+
+browser_policy_setup_parents_for() {
+  local dir=$1
+  local parent
+
+  for parent in "${BROWSER_POLICY_PARENT_DIRS[@]}"; do
+    [[ $dir == "$parent"/* ]] || continue
+    browser_policy_setup_parent "$parent"
+  done
+}
+
+browser_policy_setup_dir() {
+  local dir=$1
+
+  browser_policy_setup_parents_for "$dir"
+  browser_policy_setup_parent "$dir"
+  browser_policy_purge_dir "$dir"
+}
+
+# Themes are user-installed. Accept only three 0-255 components.
+browser_policy_theme_hex() {
+  local theme_rgb=$1
+
+  if [[ $theme_rgb =~ ^[[:space:]]*([0-9]{1,3})[[:space:]]*,[[:space:]]*([0-9]{1,3})[[:space:]]*,[[:space:]]*([0-9]{1,3})[[:space:]]*$ ]] &&
+    (( 10#${BASH_REMATCH[1]} < 256 && 10#${BASH_REMATCH[2]} < 256 && 10#${BASH_REMATCH[3]} < 256 )); then
+    printf '#%02x%02x%02x' "$((10#${BASH_REMATCH[1]}))" "$((10#${BASH_REMATCH[2]}))" "$((10#${BASH_REMATCH[3]}))"
+    return
+  fi
+
+  printf '%s' "$BROWSER_POLICY_DEFAULT_COLOR"
+}
+
+browser_policy_install_color() {
+  local policy_dir=$1
+  local hex=$2
+  local dest=$policy_dir/color.json
+  local tmp
+
+  [[ -d $policy_dir && ! -L $policy_dir ]] || return 0
+  [[ $hex =~ ^#[0-9a-f]{6}$ ]] || return 1
+
+  tmp=$(mktemp) || return 1
+  printf '{"BrowserThemeColor": "%s", "BrowserColorScheme": "device"}\n' "$hex" >"$tmp"
+
+  if [[ -L $dest || -d $dest ]]; then
+    if ! rm -rf -- "$dest" 2>/dev/null; then
+      rm -f "$tmp"
+      return 1
+    fi
+  fi
+
+  if install -m 0644 -T "$tmp" "$dest" 2>/dev/null; then
+    rm -f "$tmp"
+    return 0
+  fi
+
+  rm -f "$tmp"
+  return 1
+}
+
+browser_policy_firefox_policy_file_ok() {
+  local file=$1
+  local mode
+  local group_write
+  local other_write
+
+  [[ -f $file && ! -L $file ]] || return 1
+  [[ $(stat -c '%U' "$file") == "root" ]] || return 1
+  mode=$(stat -c '%a' "$file")
+  group_write=$((8#${mode: -2:1}))
+  other_write=$((8#${mode: -1}))
+  (( (group_write & 2) == 0 && (other_write & 2) == 0 ))
+}
+
+browser_policy_firefox_hardened() {
+  local dir=$1
+
+  [[ -d $dir && ! -L $dir ]] || return 1
+  [[ $(stat -c '%a' "$dir") == "755" ]] || return 1
+  [[ $(stat -c '%U' "$dir") == "root" ]] || return 1
+  browser_policy_firefox_policy_file_ok "$dir/policies.json"
+}
+
+browser_policy_install_firefox_policies() {
+  local distribution_dir=$1
+  local policies=${2:-$OMARCHY_PATH/default/firefox/policies.json}
+
+  as_root install -m 644 -o root -g root -T "$policies" "$distribution_dir/policies.json"
+}
+
+browser_policy_setup_firefox_distribution() {
+  local distribution_dir=$1
+  local policies=${2:-$OMARCHY_PATH/default/firefox/policies.json}
+
+  browser_policy_setup_parent "$distribution_dir"
+  browser_policy_purge_dir "$distribution_dir"
+  browser_policy_install_firefox_policies "$distribution_dir" "$policies"
+}
diff --git a/migrations/1787515927.sh b/migrations/1787515927.sh
new file mode 100644
index 00000000..f1f33869
--- /dev/null
+++ b/migrations/1787515927.sh
@@ -0,0 +1,27 @@
+echo "Stop world-writable Chromium and Firefox policy directories"
+
+source "$OMARCHY_PATH/install/helpers/browser-policy.sh"
+
+repaired=0
+for dir in "${BROWSER_POLICY_MANAGED_DIRS[@]}"; do
+  [[ -d $dir || -L $dir ]] || continue
+  browser_policy_setup_dir "$dir"
+  repaired=1
+done
+
+if (( repaired )); then
+  omarchy-theme-set-browser
+fi
+
+for dir in "${BROWSER_POLICY_FIREFOX_DIRS[@]}"; do
+  [[ -d $dir || -L $dir ]] || continue
+  if browser_policy_firefox_hardened "$dir"; then
+    browser_policy_purge_dir "$dir"
+    continue
+  fi
+  browser_policy_setup_parent "$dir"
+  browser_policy_purge_dir "$dir"
+  if ! browser_policy_firefox_policy_file_ok "$dir/policies.json"; then
+    browser_policy_install_firefox_policies "$dir"
+  fi
+done
diff --git a/test/shell.d/browser-policy-dir-test.sh b/test/shell.d/browser-policy-dir-test.sh
new file mode 100755
index 00000000..20b8067c
--- /dev/null
+++ b/test/shell.d/browser-policy-dir-test.sh
@@ -0,0 +1,311 @@
+#!/bin/bash
+
+set -euo pipefail
+
+source "$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)/base-test.sh"
+
+test_tmp=$(mktemp -d)
+trap 'rm -rf "$test_tmp"' EXIT
+
+export OMARCHY_PATH="$ROOT"
+export OMARCHY_PROVISIONING_DIR="$test_tmp/provisioning"
+
+source "$ROOT/install/helpers/browser-policy.sh"
+
+# Temp dirs are user-owned; drop -o/-g so install(1) can run unprivileged.
+unprivileged_as_root() {
+  if [[ $1 == "install" ]]; then
+    shift
+    local args=()
+    local skip=0
+    local arg
+    for arg in "$@"; do
+      if (( skip )); then
+        skip=0
+        continue
+      fi
+      case $arg in
+        -o|-g) skip=1 ;;
+        *) args+=("$arg") ;;
+      esac
+    done
+    command install "${args[@]}"
+  else
+    "$@"
+  fi
+}
+
+write_dir=$test_tmp/writable
+mkdir -p "$write_dir"
+browser_policy_install_color "$write_dir" "#aabbcc" ||
+  fail "theme colour writes into a writable policy directory"
+grep -F '"BrowserThemeColor": "#aabbcc"' "$write_dir/color.json" >/dev/null ||
+  fail "theme colour writes BrowserThemeColor"
+mode=$(stat -c '%a' "$write_dir/color.json")
+[[ $mode == "644" ]] || fail "theme colour creates a root-mode policy file" "mode=$mode"
+pass "theme colour writes a 0644 color.json"
+
+if (( EUID == 0 )); then
+  pass "running as root; skipping the mktemp-failure check"
+else
+  chmod u+w "$write_dir"
+  export TMPDIR=$test_tmp/missing-tmp
+  if browser_policy_install_color "$write_dir" "#dead00" 2>/dev/null; then
+    fail "theme colour fails when mktemp cannot create a file"
+  fi
+  unset TMPDIR
+  grep -F '"BrowserThemeColor": "#aabbcc"' "$write_dir/color.json" >/dev/null ||
+    fail "a failed mktemp leaves an existing color.json intact"
+  pass "a failed mktemp does not truncate color.json"
+fi
+
+printf 'original\n' >"$test_tmp/pwn"
+rm -f "$write_dir/color.json"
+ln -s "$test_tmp/pwn" "$write_dir/color.json"
+browser_policy_install_color "$write_dir" "#aabbcc" ||
+  fail "theme colour replaces a planted color.json symlink"
+[[ -f $write_dir/color.json && ! -L $write_dir/color.json ]] ||
+  fail "theme colour unlinks a planted color.json symlink instead of writing through it"
+grep -Fxq 'original' "$test_tmp/pwn" || fail "theme colour leaves the symlink target unchanged"
+pass "theme colour does not follow a planted color.json symlink"
+
+plant_write=$test_tmp/plant-dir
+mkdir -p "$plant_write/color.json/nested"
+printf 'inside\n' >"$plant_write/color.json/nested/x"
+browser_policy_install_color "$plant_write" "#aabbcc" ||
+  fail "theme colour replaces a planted color.json directory"
+[[ -f $plant_write/color.json && ! -d $plant_write/color.json ]] ||
+  fail "theme colour does not write into a planted color.json directory"
+pass "theme colour does not write into a planted color.json directory"
+
+missing_dir=$test_tmp/missing
+browser_policy_install_color "$missing_dir" "#aabbcc" ||
+  fail "theme colour skips a policy directory that does not exist"
+[[ ! -e $missing_dir ]] || fail "theme colour does not create a missing policy directory"
+pass "theme colour skips a missing policy directory"
+
+if browser_policy_install_color "$write_dir" "aabbcc" 2>/dev/null; then
+  fail "theme colour rejects hex without a leading #"
+fi
+if browser_policy_install_color "$write_dir" "#AABBCC" 2>/dev/null; then
+  fail "theme colour rejects uppercase hex"
+fi
+pass "theme colour accepts only # plus six lowercase hex digits"
+
+planted_dir=$test_tmp/planted
+mkdir -p "$planted_dir/evil"
+printf 'evil\n' >"$planted_dir/evil/f"
+printf 'old\n' >"$planted_dir/color.json"
+as_root() { unprivileged_as_root "$@"; }
+browser_policy_setup_dir "$planted_dir"
+[[ ! -e $planted_dir/evil ]] || fail "policy setup drops a non-empty non-root subdirectory"
+[[ ! -e $planted_dir/color.json ]] || fail "policy setup drops a non-root color.json"
+[[ -d $planted_dir ]] || fail "policy setup leaves the managed directory in place"
+mode=$(stat -c '%a' "$planted_dir")
+[[ $mode == "755" ]] || fail "policy setup leaves the managed directory 0755" "mode=$mode"
+pass "policy setup drops non-root files and non-empty subdirectories"
+
+owned=$test_tmp/not-root
+mkdir -p "$owned"
+chmod 755 "$owned"
+if browser_policy_dir_hardened "$owned"; then
+  fail "a user-owned 0755 directory is not treated as hardened"
+fi
+pass "a hardened directory must be root-owned"
+
+saved_parent_dirs=("${BROWSER_POLICY_PARENT_DIRS[@]}")
+parent_root=$test_tmp/parents
+mkdir -p "$parent_root/etc/chromium/policies/managed/keep"
+printf 'keep\n' >"$parent_root/etc/chromium/policies/managed/keep/x"
+chmod 0777 "$parent_root/etc/chromium" "$parent_root/etc/chromium/policies"
+chmod 755 "$parent_root/etc/chromium/policies/managed"
+BROWSER_POLICY_PARENT_DIRS=(
+  "$parent_root/etc/chromium"
+  "$parent_root/etc/chromium/policies"
+)
+as_root() { unprivileged_as_root "$@"; }
+if browser_policy_parents_hardened "$parent_root/etc/chromium/policies/managed"; then
+  fail "a world-writable policy parent is not treated as hardened"
+fi
+browser_policy_setup_parents_for "$parent_root/etc/chromium/policies/managed"
+mode=$(stat -c '%a' "$parent_root/etc/chromium")
+[[ $mode == "755" ]] || fail "setup tightens /etc/chromium" "mode=$mode"
+mode=$(stat -c '%a' "$parent_root/etc/chromium/policies")
+[[ $mode == "755" ]] || fail "setup tightens /etc/chromium/policies" "mode=$mode"
+[[ -d $parent_root/etc/chromium/policies/managed/keep ]] ||
+  fail "parent repair does not purge the managed directory"
+pass "policy parent directories are tightened to 0755 without purging the leaf"
+
+symlink_root=$test_tmp/symlink-parents
+mkdir -p "$symlink_root/etc" "$symlink_root/attacker/policies/managed"
+printf 'planted\n' >"$symlink_root/attacker/policies/managed/evil.json"
+ln -s "$symlink_root/attacker" "$symlink_root/etc/chromium"
+BROWSER_POLICY_PARENT_DIRS=(
+  "$symlink_root/etc/chromium"
+  "$symlink_root/etc/chromium/policies"
+)
+as_root() { unprivileged_as_root "$@"; }
+browser_policy_setup_dir "$symlink_root/etc/chromium/policies/managed"
+[[ ! -L $symlink_root/etc/chromium ]] || fail "setup replaces a planted /etc/chromium symlink"
+[[ -d $symlink_root/etc/chromium && ! -L $symlink_root/etc/chromium ]] ||
+  fail "setup recreates /etc/chromium as a real directory"
+[[ -d $symlink_root/etc/chromium/policies && ! -L $symlink_root/etc/chromium/policies ]] ||
+  fail "setup recreates /etc/chromium/policies as a real directory"
+[[ ! -e $symlink_root/etc/chromium/policies/managed/evil.json ]] ||
+  fail "setup does not keep policy that lived behind a planted parent symlink"
+grep -Fxq 'planted' "$symlink_root/attacker/policies/managed/evil.json" ||
+  fail "replacing a parent symlink does not delete the symlink target"
+BROWSER_POLICY_PARENT_DIRS=("${saved_parent_dirs[@]}")
+pass "policy setup does not follow a planted parent symlink"
+
+leaf_link_root=$test_tmp/leaf-link
+mkdir -p "$leaf_link_root/etc/chromium/policies" "$leaf_link_root/attacker"
+printf 'planted\n' >"$leaf_link_root/attacker/evil.json"
+chmod 755 "$leaf_link_root/etc/chromium" "$leaf_link_root/etc/chromium/policies"
+ln -s "$leaf_link_root/attacker" "$leaf_link_root/etc/chromium/policies/managed"
+BROWSER_POLICY_PARENT_DIRS=(
+  "$leaf_link_root/etc/chromium"
+  "$leaf_link_root/etc/chromium/policies"
+)
+as_root() { unprivileged_as_root "$@"; }
+if browser_policy_dir_hardened "$leaf_link_root/etc/chromium/policies/managed"; then
+  fail "a planted managed symlink is not treated as hardened"
+fi
+browser_policy_setup_dir "$leaf_link_root/etc/chromium/policies/managed"
+[[ ! -L $leaf_link_root/etc/chromium/policies/managed ]] ||
+  fail "setup replaces a planted managed symlink"
+[[ -d $leaf_link_root/etc/chromium/policies/managed && ! -L $leaf_link_root/etc/chromium/policies/managed ]] ||
+  fail "setup recreates managed as a real directory"
+[[ ! -e $leaf_link_root/etc/chromium/policies/managed/evil.json ]] ||
+  fail "setup does not keep policy that lived behind a planted managed symlink"
+grep -Fxq 'planted' "$leaf_link_root/attacker/evil.json" ||
+  fail "replacing a managed symlink does not delete the symlink target"
+BROWSER_POLICY_PARENT_DIRS=("${saved_parent_dirs[@]}")
+pass "policy setup does not follow a planted managed symlink"
+
+fx_link_root=$test_tmp/fx-link
+mkdir -p "$fx_link_root/attacker" "$fx_link_root/opt"
+printf 'planted\n' >"$fx_link_root/attacker/policies.json"
+ln -s "$fx_link_root/attacker" "$fx_link_root/opt/zen"
+as_root() { unprivileged_as_root "$@"; }
+if browser_policy_firefox_hardened "$fx_link_root/opt/zen"; then
+  fail "a planted Firefox distribution symlink is not treated as hardened"
+fi
+browser_policy_setup_firefox_distribution "$fx_link_root/opt/zen" ||
+  fail "Firefox setup replaces a planted distribution symlink"
+[[ ! -L $fx_link_root/opt/zen ]] || fail "Firefox setup unlinks a planted distribution symlink"
+[[ -d $fx_link_root/opt/zen && ! -L $fx_link_root/opt/zen ]] ||
+  fail "Firefox setup recreates the distribution directory"
+[[ -f $fx_link_root/opt/zen/policies.json && ! -L $fx_link_root/opt/zen/policies.json ]] ||
+  fail "Firefox setup writes policies.json into the recreated directory"
+grep -Fxq 'planted' "$fx_link_root/attacker/policies.json" ||
+  fail "replacing a Firefox distribution symlink does not delete the symlink target"
+pass "Firefox setup does not follow a planted distribution symlink"
+
+[[ $(browser_policy_theme_hex "242,240,229") == "#f2f0e5" ]] ||
+  fail "theme colour converts an RGB triple to hex"
+[[ $(browser_policy_theme_hex $'14,31,41\n') == "#0e1f29" ]] ||
+  fail "theme colour accepts a trailing newline"
+[[ $(browser_policy_theme_hex "0,0,0") == "#000000" ]] ||
+  fail "theme colour pads single-digit components"
+[[ $(browser_policy_theme_hex " 12 , 11 , 12 ") == "#0c0b0c" ]] ||
+  fail "theme colour tolerates surrounding whitespace"
+[[ $(browser_policy_theme_hex "08,09,10") == "#08090a" ]] ||
+  fail "theme colour treats leading zeros as decimal"
+for malformed in "" "not,a,color" "1,2" "1,2,3,4" "256,0,0" "999,999,999" "-1,0,0" \
+  "1,2,3;id" '1,2,$(id)' "0x10,0,0" "1,2,3 4,5,6"; do
+  [[ $(browser_policy_theme_hex "$malformed") == "#1c2027" ]] ||
+    fail "theme colour falls back to the stock grey for '$malformed'"
+done
+pass "theme colour is six hex digits or the stock grey"
+
+for theme in "$ROOT"/themes/*/chromium.theme; do
+  [[ -f $theme ]] || continue
+  rgb=$(<$theme)
+  hex=$(browser_policy_theme_hex "$rgb")
+  [[ $hex =~ ^#[0-9a-f]{6}$ ]] ||
+    fail "shipped $(basename "$(dirname "$theme")") chromium.theme parses as hex" "got: $hex from $(printf %q "$rgb")"
+  if [[ $hex == "#1c2027" && ! $rgb =~ ^[[:space:]]*28[[:space:]]*,[[:space:]]*32[[:space:]]*,[[:space:]]*39[[:space:]]*$ ]]; then
+    fail "shipped $(basename "$(dirname "$theme")") chromium.theme is a valid RGB triple" "got: $(printf %q "$rgb")"
+  fi
+done
+pass "shipped chromium.theme files parse as RGB triples"
+
+grep -F 'browser_policy_theme_hex' "$ROOT/bin/omarchy-theme-set-browser" >/dev/null ||
+  fail "omarchy-theme-set-browser parses chromium.theme through browser_policy_theme_hex"
+grep -F 'omarchy-theme-set-browser-policy' "$ROOT/bin/omarchy-theme-set-browser" >/dev/null ||
+  fail "omarchy-theme-set-browser writes colour through omarchy-theme-set-browser-policy"
+if grep -E 'printf.*THEME_RGB_COLOR' "$ROOT/bin/omarchy-theme-set-browser" >/dev/null; then
+  fail "omarchy-theme-set-browser does not hand unvetted theme words to printf"
+fi
+pass "omarchy-theme-set-browser validates the theme colour"
+
+fx_policy=$test_tmp/policies.json
+printf '%s\n' '{"policies":{}}' >"$fx_policy"
+chmod 644 "$fx_policy"
+if browser_policy_firefox_policy_file_ok "$fx_policy"; then
+  fail "a user-owned policies.json is not treated as hardened"
+fi
+ln -sf "$fx_policy" "$test_tmp/policies-link.json"
+if browser_policy_firefox_policy_file_ok "$test_tmp/policies-link.json"; then
+  fail "a policies.json symlink is not treated as hardened"
+fi
+pass "Firefox policy files must be root-owned regular files without group or other write"
+
+dist=$test_tmp/distribution
+mkdir -p "$dist"
+printf 'original\n' >"$test_tmp/firefox-pwn"
+ln -s "$test_tmp/firefox-pwn" "$dist/policies.json"
+as_root() { unprivileged_as_root "$@"; }
+browser_policy_install_firefox_policies "$dist" ||
+  fail "Firefox policy install replaces a planted policies.json symlink"
+[[ -f $dist/policies.json && ! -L $dist/policies.json ]] ||
+  fail "Firefox policy install unlinks a planted policies.json symlink instead of writing through it"
+grep -Fxq 'original' "$test_tmp/firefox-pwn" || fail "Firefox policy install leaves the symlink target unchanged"
+grep -q '"policies"' "$dist/policies.json" || fail "Firefox policy install writes the stock policies"
+pass "Firefox policy install does not follow a planted policies.json symlink"
+
+dir_dist=$test_tmp/distribution-dir
+mkdir -p "$dir_dist"
+mkdir "$dir_dist/policies.json"
+as_root() { unprivileged_as_root "$@"; }
+if browser_policy_install_firefox_policies "$dir_dist" 2>/dev/null; then
+  fail "Firefox policy install refuses a planted policies.json directory"
+fi
+[[ -d $dir_dist/policies.json ]] || fail "Firefox policy install leaves a planted policies.json directory in place"
+pass "Firefox policy install does not write into a planted policies.json directory"
+
+grep -F 'exit "$failed"' "$ROOT/bin/omarchy-theme-set-browser" >/dev/null ||
+  fail "omarchy-theme-set-browser exits non-zero when a policy write fails"
+pass "omarchy-theme-set-browser exits non-zero when a policy write fails"
+
+policy_files=(
+  "$ROOT/bin/omarchy-install-browser"
+  "$ROOT/bin/omarchy-provision-owner"
+  "$ROOT/bin/omarchy-theme-set-browser"
+  "$ROOT/bin/omarchy-theme-set-browser-policy"
+  "$ROOT/bin/omarchy-upgrade-to-quattro"
+  "$ROOT/install/config/theme-system.sh"
+  "$ROOT/install/config/browser-policy.sh"
+  "$ROOT/install/helpers/browser-policy.sh"
+  "$ROOT/migrations/1787515927.sh"
+)
+if grep -nE 'chmod a\+rwx\b|chmod a\+rw\b|chmod a\+w\b|chmod o\+w|chmod ugo\+w|chmod 2775\b|chmod 2777\b|chmod 0777\b|chmod 777\b|install -d -m 0?[27]?777|omarchy-browser-policy' "${policy_files[@]}" >/dev/null; then
+  fail "browser policy setup is not world-writable and does not use omarchy-browser-policy"
+fi
+pass "browser policy setup is not world-writable"
+
+mapfile -t migrations < <(rg -l 'Stop world-writable Chromium and Firefox policy directories' "$ROOT/migrations")
+(( ${#migrations[@]} == 1 )) || fail "exactly one migration locks existing policy directories" "${migrations[*]}"
+grep -F 'browser_policy_setup_dir' "${migrations[0]}" >/dev/null ||
+  fail "the policy-directory migration repairs managed directories"
+if grep -F 'browser_policy_grant_user' "${migrations[0]}" >/dev/null; then
+  fail "the policy-directory migration does not grant a browser-policy group"
+fi
+grep -F 'BROWSER_POLICY_FIREFOX_DIRS' "${migrations[0]}" >/dev/null ||
+  fail "the policy-directory migration covers Firefox and Zen"
+grep -F 'browser_policy_firefox_policy_file_ok' "${migrations[0]}" >/dev/null ||
+  fail "the policy-directory migration keeps a trusted Firefox policies.json"
+grep -F '/opt/zen-browser/distribution' "$ROOT/install/helpers/browser-policy.sh" >/dev/null ||
+  fail "the shared helper names the Zen distribution directory"
+pass "a migration locks existing policy directories"
diff --git a/test/shell.d/browser-policy-sudoers-test.sh b/test/shell.d/browser-policy-sudoers-test.sh
new file mode 100755
index 00000000..2af8ea2b
--- /dev/null
+++ b/test/shell.d/browser-policy-sudoers-test.sh
@@ -0,0 +1,184 @@
+#!/bin/bash
+
+set -euo pipefail
+
+source "$(dirname "$0")/base-test.sh"
+
+helper="$ROOT/bin/omarchy-theme-set-browser-policy"
+setter="$ROOT/bin/omarchy-theme-set-browser"
+sudoers_file="$ROOT/etc/sudoers.d/omarchy-theme-browser"
+rule='%wheel ALL=(root) NOPASSWD: /usr/bin/omarchy-theme-set-browser-policy [0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]'
+
+# Exactly one rule, matched whole. Dropping the argument -- which sudoers reads
+# as "any arguments" -- or widening the glob to `*` would let the grant carry
+# something other than a color while leaving this line looking right.
+rules=$(grep -vE '^[[:space:]]*(#|$)' "$sudoers_file")
+[[ $rules == "$rule" ]] ||
+  fail "browser policy sudoers file carries exactly the six-hex-digit rule and nothing else" "got: $rules"
+
+if command -v visudo >/dev/null; then
+  visudo -cf "$sudoers_file" >/dev/null || fail "browser policy sudoers rule parses"
+fi
+
+grep -Fx 'PACKAGED_PATH=/usr/bin/omarchy-theme-set-browser-policy' "$helper" >/dev/null ||
+  fail "omarchy-theme-set-browser-policy elevates the path the sudoers rule names"
+
+grep -E 'sudo -n -l -l' "$helper" >/dev/null ||
+  fail "omarchy-theme-set-browser-policy reads the grant from the long sudo listing"
+
+grep -Eq '^\s*export PATH=/usr/local/sbin:/usr/local/bin:/usr/bin' "$helper" ||
+  fail "omarchy-theme-set-browser-policy pins PATH to trusted system directories when it holds root"
+gated=$(grep -A1 -E '^if \(\( EUID == 0 \)\); then$' "$helper" || true)
+[[ $gated == *"export PATH=/usr/local/sbin:/usr/local/bin:/usr/bin"* ]] ||
+  fail "omarchy-theme-set-browser-policy gates the trusted-PATH pin on holding root"
+
+pass "browser policy sudoers rule is scoped to a single color argument"
+
+for dir in /etc/chromium/policies/managed /etc/opt/chrome/policies/managed \
+  /etc/opt/edge/policies/managed /etc/brave/policies/managed; do
+  grep -Fx "  $dir" "$helper" >/dev/null ||
+    fail "omarchy-theme-set-browser-policy names $dir in its fixed policy directory list"
+done
+
+policy_dir_count=$(sed -n '/^POLICY_DIRS=(/,/^)/p' "$helper" | grep -c '^  /')
+((policy_dir_count == 4)) ||
+  fail "omarchy-theme-set-browser-policy writes only the four known policy directories" \
+    "got: $policy_dir_count"
+
+grep -F 'install -m 0644 -o root -g root -T' "$helper" >/dev/null ||
+  fail "omarchy-theme-set-browser-policy installs color.json with install -T"
+if grep -E 'mv -f' "$helper" >/dev/null; then
+  fail "omarchy-theme-set-browser-policy does not mv into a planted color.json directory"
+fi
+
+pass "browser policy helper writes a fixed set of policy directories"
+
+test_tmp=$(mktemp -d)
+trap 'rm -rf "$test_tmp"' EXIT
+
+stub_bin="$test_tmp/bin"
+mkdir -p "$stub_bin"
+
+cat >"$stub_bin/pkexec" <<'SH'
+#!/bin/bash
+printf 'pkexec %s\n' "$*" >"$ELEVATION_LOG"
+SH
+chmod +x "$stub_bin/pkexec"
+
+# STUB_GRANTED empty stands for an install whose omarchy-settings predates the
+# sudoers file. The default is granted, matching a current Omarchy.
+cat >"$stub_bin/sudo" <<'SH'
+#!/bin/bash
+if [[ $1 == -n && $2 == -l ]]; then
+  if [[ ${STUB_GRANTED-granted} == "granted" ]]; then
+    echo "    Options: !authenticate"
+  else
+    echo "    Matched: ${!#}"
+  fi
+  exit 0
+fi
+printf 'sudo %s\n' "$*" >"$ELEVATION_LOG"
+SH
+chmod +x "$stub_bin/sudo"
+
+if ((EUID == 0)); then
+  pass "running as root; skipping the elevation checks, which would rewrite this machine's browser policy"
+else
+  elevation_for() {
+    : >"$test_tmp/elevation"
+    ELEVATION_LOG="$test_tmp/elevation" \
+      PATH="$stub_bin:$PATH" \
+      bash "$helper" "$@" </dev/null >/dev/null 2>&1 || true
+    cat "$test_tmp/elevation"
+  }
+
+  elevation=$(elevation_for 1c2027)
+  [[ $elevation == "sudo /usr/bin/omarchy-theme-set-browser-policy 1c2027" ]] ||
+    fail "omarchy-theme-set-browser-policy takes the passwordless sudo grant without a terminal" \
+      "got: $elevation"
+
+  dev_linked=$(OMARCHY_PATH="$test_tmp/checkout" elevation_for 1c2027)
+  [[ $dev_linked == "sudo /usr/bin/omarchy-theme-set-browser-policy 1c2027" ]] ||
+    fail "omarchy-theme-set-browser-policy elevates the system install wherever OMARCHY_PATH points" \
+      "got: $dev_linked"
+
+  pass "browser policy helper elevates a valid color through the sudo grant"
+
+  ungranted=$(STUB_GRANTED="" elevation_for 1c2027)
+  [[ $ungranted == "pkexec /usr/bin/omarchy-theme-set-browser-policy 1c2027" ]] ||
+    fail "omarchy-theme-set-browser-policy falls back to polkit where the grant does not reach" \
+      "got: $ungranted"
+
+  pass "browser policy helper falls back to polkit wherever the grant does not reach"
+
+  for bad in "" "1C2027" "abc12" "abc1234" "1c202g" "../../etc/passwd" "1c2027 1c2027" \
+    '$(id)' "1c2027;id" "#1c2027"; do
+    if PATH="$stub_bin:$PATH" ELEVATION_LOG="$test_tmp/elevation" \
+      bash "$helper" "$bad" </dev/null >/dev/null 2>&1; then
+      fail "omarchy-theme-set-browser-policy rejects '$bad'"
+    fi
+
+    rejected=$(elevation_for "$bad")
+    [[ -z $rejected ]] ||
+      fail "omarchy-theme-set-browser-policy rejects '$bad' before elevating" "got: $rejected"
+  done
+
+  if PATH="$stub_bin:$PATH" bash "$helper" 1c2027 ffffff </dev/null >/dev/null 2>&1; then
+    fail "omarchy-theme-set-browser-policy rejects more than one argument"
+  fi
+
+  pass "browser policy helper accepts nothing but six lowercase hex digits"
+fi
+
+setter_bin="$test_tmp/setter-bin"
+mkdir -p "$setter_bin"
+
+cat >"$setter_bin/omarchy-theme-set-browser-policy" <<'SH'
+#!/bin/bash
+printf '%s\n' "$*" >"$COLOR_LOG"
+SH
+chmod +x "$setter_bin/omarchy-theme-set-browser-policy"
+
+cat >"$setter_bin/omarchy-cmd-present" <<'SH'
+#!/bin/bash
+exit 1
+SH
+chmod +x "$setter_bin/omarchy-cmd-present"
+
+setter_home="$test_tmp/home"
+theme_dir="$setter_home/.local/state/omarchy/current/theme"
+mkdir -p "$theme_dir"
+
+color_for_theme() {
+  : >"$test_tmp/color"
+  if [[ $# -gt 0 ]]; then
+    printf '%s' "$1" >"$theme_dir/chromium.theme"
+  else
+    rm -f "$theme_dir/chromium.theme"
+  fi
+
+  HOME="$setter_home" COLOR_LOG="$test_tmp/color" PATH="$setter_bin:$stub_bin:$PATH" \
+    OMARCHY_PATH="$ROOT" bash "$setter" </dev/null >/dev/null 2>&1 || true
+  cat "$test_tmp/color"
+}
+
+[[ $(color_for_theme "242,240,229") == "f2f0e5" ]] ||
+  fail "omarchy-theme-set-browser converts an RGB triple to six hex digits"
+[[ $(color_for_theme $'14,31,41\n') == "0e1f29" ]] ||
+  fail "omarchy-theme-set-browser accepts a trailing newline"
+[[ $(color_for_theme "0,0,0") == "000000" ]] ||
+  fail "omarchy-theme-set-browser pads single-digit components"
+[[ $(color_for_theme " 12 , 11 , 12 ") == "0c0b0c" ]] ||
+  fail "omarchy-theme-set-browser tolerates surrounding whitespace"
+
+for malformed in "" "not,a,color" "1,2" "1,2,3,4" "256,0,0" "999,999,999" "-1,0,0" \
+  "1,2,3;id" '1,2,$(id)' "0x10,0,0" "1,2,3 4,5,6"; do
+  color=$(color_for_theme "$malformed")
+  [[ $color == "1c2027" ]] ||
+    fail "omarchy-theme-set-browser falls back to the stock colour for '$malformed'" "got: $color"
+done
+
+[[ $(color_for_theme) == "1c2027" ]] ||
+  fail "omarchy-theme-set-browser falls back to the stock colour with no theme file"
+
+pass "browser theme color is derived as six hex digits or falls back to the stock grey"
diff --git a/test/shell.d/default-apps-test.sh b/test/shell.d/default-apps-test.sh
index aa07659d..8151c250 100755
--- a/test/shell.d/default-apps-test.sh
+++ b/test/shell.d/default-apps-test.sh
@@ -61,11 +61,13 @@ if [[ $installer == "omarchy-install-browser" && ${OMARCHY_TEST_REAL_BROWSER_INS
 fi
 
 case $installer in
-omarchy-pkg-add)
+omarchy-pkg-add|omarchy-pkg-aur-add)
   package=$1
   printf 'pkg:%s\n' "$package" >>"$OMARCHY_TEST_INSTALL_LOG"
   case $package in
   chromium) command=chromium ;;
+  firefox) command=firefox ;;
+  zen-browser-bin) command=zen-browser ;;
   cursor-bin) command=cursor ;;
   sublime-text-4) command=sublime_text ;;
   vim) command=vim ;;
@@ -107,6 +109,7 @@ SH
 
 for installer in \
   omarchy-pkg-add \
+  omarchy-pkg-aur-add \
   omarchy-install-browser \
   omarchy-install-terminal \
   omarchy-install-editor-vscode \
@@ -205,10 +208,17 @@ OMARCHY_TEST_REAL_BROWSER_INSTALL=true omarchy-default-browser --install chromiu
 [[ $(omarchy-default-browser) == "chromium" ]] || fail "Chromium becomes the default after its full installer succeeds"
 cmp -s "$ROOT/config/chromium-flags.conf" "$test_home/.config/chromium-flags.conf" ||
   fail "Chromium browser installer copies the default flags"
-grep -Fxq 'sudo:mkdir -p /etc/chromium/policies/managed' "$setup_log" ||
-  fail "Chromium browser installer creates its policy directory"
-grep -Fxq 'sudo:chmod a+rw /etc/chromium/policies/managed' "$setup_log" ||
-  fail "Chromium browser installer makes its policy directory writable"
+grep -Fxq 'sudo:install -d -m 0755 -o root -g root /etc/chromium' "$setup_log" ||
+  fail "Chromium browser installer creates a root-owned Chromium policy parent"
+grep -Fxq 'sudo:install -d -m 0755 -o root -g root /etc/chromium/policies' "$setup_log" ||
+  fail "Chromium browser installer creates a root-owned Chromium policies parent"
+grep -Fxq 'sudo:install -d -m 0755 -o root -g root /etc/chromium/policies/managed' "$setup_log" ||
+  fail "Chromium browser installer creates a root-owned managed policy directory"
+grep -Fxq 'sudo:find /etc/chromium/policies/managed -mindepth 1 -maxdepth 1 ! -user root -exec rm -rf -- {} +' "$setup_log" ||
+  fail "Chromium browser installer drops non-root files from its policy directory"
+if grep -E 'groupadd|usermod|omarchy-browser-policy' "$setup_log" >/dev/null; then
+  fail "Chromium browser installer does not create a browser-policy group" "$(cat "$setup_log")"
+fi
 grep -Fxq 'omarchy-install-chromium-copy-url:' "$setup_log" ||
   fail "Chromium browser installer registers the Copy URL host"
 grep -Fxq 'omarchy-install-chromium-ytdlp:' "$setup_log" ||
@@ -217,6 +227,36 @@ grep -Fxq 'omarchy-theme-set-browser:' "$setup_log" ||
   fail "Chromium browser installer applies the current theme"
 pass "Chromium browser installer restores the complete Omarchy setup"
 
+: >"$install_log"
+: >"$setup_log"
+rm -f "$installed_dir/firefox"
+OMARCHY_TEST_REAL_BROWSER_INSTALL=true omarchy-default-browser --install firefox >/dev/null
+[[ $(<"$install_log") == "pkg:firefox" ]] || fail "Firefox browser installer installs the package"
+[[ $(omarchy-default-browser) == "firefox" ]] || fail "Firefox becomes the default after its full installer succeeds"
+grep -Fxq 'sudo:install -d -m 0755 -o root -g root /usr/lib/firefox/distribution' "$setup_log" ||
+  fail "Firefox browser installer creates its distribution directory"
+grep -Fxq 'sudo:find /usr/lib/firefox/distribution -mindepth 1 -maxdepth 1 ! -user root -exec rm -rf -- {} +' "$setup_log" ||
+  fail "Firefox browser installer drops non-root files from its distribution directory"
+grep -Fxq "sudo:install -m 644 -o root -g root -T $ROOT/default/firefox/policies.json /usr/lib/firefox/distribution/policies.json" "$setup_log" ||
+  fail "Firefox browser installer copies policies.json without following a destination symlink"
+[[ -e $installed_dir/firefox ]] || fail "Firefox browser installer marks firefox installed"
+pass "Firefox browser installer restores the complete Omarchy setup"
+
+: >"$install_log"
+: >"$setup_log"
+rm -f "$installed_dir/zen-browser"
+OMARCHY_TEST_REAL_BROWSER_INSTALL=true omarchy-default-browser --install zen >/dev/null
+[[ $(<"$install_log") == "pkg:zen-browser-bin" ]] || fail "Zen browser installer installs the package"
+[[ $(omarchy-default-browser) == "zen" ]] || fail "Zen becomes the default after its full installer succeeds"
+grep -Fxq 'sudo:install -d -m 0755 -o root -g root /opt/zen-browser/distribution' "$setup_log" ||
+  fail "Zen browser installer creates its distribution directory"
+grep -Fxq 'sudo:find /opt/zen-browser/distribution -mindepth 1 -maxdepth 1 ! -user root -exec rm -rf -- {} +' "$setup_log" ||
+  fail "Zen browser installer drops non-root files from its distribution directory"
+grep -Fxq "sudo:install -m 644 -o root -g root -T $ROOT/default/firefox/policies.json /opt/zen-browser/distribution/policies.json" "$setup_log" ||
+  fail "Zen browser installer copies policies.json without following a destination symlink"
+[[ -e $installed_dir/zen-browser ]] || fail "Zen browser installer marks zen-browser installed"
+pass "Zen browser installer restores the complete Omarchy setup"
+
 omarchy-default-browser zen
 rm -f "$installed_dir/chromium"
 if OMARCHY_TEST_REAL_BROWSER_INSTALL=true OMARCHY_TEST_INSTALL_FAIL=true \
diff --git a/test/shell.d/provisioning-groups-test.sh b/test/shell.d/provisioning-groups-test.sh
index d0eac226..5a5fc516 100644
--- a/test/shell.d/provisioning-groups-test.sh
+++ b/test/shell.d/provisioning-groups-test.sh
@@ -27,16 +27,41 @@ cat >"$TMPDIR/bin/usermod" <<STUB
 #!/bin/bash
 echo "\$@" >>"$TMPDIR/usermod.calls"
 STUB
-chmod +x "$TMPDIR/bin/getent" "$TMPDIR/bin/usermod"
+cat >"$TMPDIR/bin/groupadd" <<STUB
+#!/bin/bash
+echo "\$@" >>"$TMPDIR/groupadd.calls"
+STUB
+cat >"$TMPDIR/bin/install" <<STUB
+#!/bin/bash
+echo "\$@" >>"$TMPDIR/install.calls"
+STUB
+cat >"$TMPDIR/bin/find" <<STUB
+#!/bin/bash
+echo "\$@" >>"$TMPDIR/find.calls"
+STUB
+cat >"$TMPDIR/bin/sudo" <<STUB
+#!/bin/bash
+echo "\$@" >>"$TMPDIR/sudo.calls"
+exec "\$@"
+STUB
+chmod +x "$TMPDIR/bin"/{getent,usermod,groupadd,install,find,sudo}
 export PATH="$TMPDIR/bin:$PATH"
+export OMARCHY_PATH="$ROOT"
 
-# No install user (deferred-provisioning install): input recorded, usermod not called.
+# No install user (deferred-provisioning install): groups recorded, usermod not called.
 OMARCHY_INSTALL_USER="" bash -eE "$ROOT/install/config/docker.sh"
 OMARCHY_INSTALL_USER="" bash -eE "$ROOT/install/hardware/input-group.sh"
+OMARCHY_INSTALL_USER="" bash -eE "$ROOT/install/config/browser-policy.sh"
 
 [[ -f $OMARCHY_PROVISIONING_DIR/groups ]] || fail "groups file written without an install user"
 grep -qxF input "$OMARCHY_PROVISIONING_DIR/groups" || fail "input group recorded"
+! grep -qxF omarchy-browser-policy "$OMARCHY_PROVISIONING_DIR/groups" ||
+  fail "browser-policy group must not be recorded"
 [[ ! -f $TMPDIR/usermod.calls ]] || fail "usermod not called without an install user"
+[[ ! -f $TMPDIR/groupadd.calls ]] || ! grep -F omarchy-browser-policy "$TMPDIR/groupadd.calls" >/dev/null ||
+  fail "browser-policy group is not created"
+grep -F -- '-d -m 0755 -o root -g root /etc/chromium/policies/managed' "$TMPDIR/install.calls" >/dev/null ||
+  fail "browser-policy directory is created root-owned"
 pass "deferred provisioning records groups without calling usermod"
 
 # The docker group is root-equivalent and must never be granted automatically.
@@ -45,17 +70,22 @@ pass "docker group is not recorded at install"
 
 # Missing user (defensive): no usermod either.
 OMARCHY_INSTALL_USER=ghost bash -eE "$ROOT/install/hardware/input-group.sh"
+OMARCHY_INSTALL_USER=ghost bash -eE "$ROOT/install/config/browser-policy.sh"
 [[ ! -f $TMPDIR/usermod.calls ]] || fail "usermod not called for a missing user"
 pass "missing install user defers group grants"
 
 # Re-running never duplicates entries.
 OMARCHY_INSTALL_USER="" bash -eE "$ROOT/install/hardware/input-group.sh"
 [[ $(grep -cxF input "$OMARCHY_PROVISIONING_DIR/groups") == 1 ]] || fail "input group recorded once"
+OMARCHY_INSTALL_USER="" bash -eE "$ROOT/install/config/browser-policy.sh"
 pass "group recording is idempotent"
 
 # Existing user: usermod applies the recorded groups, and docker is never among them.
 OMARCHY_INSTALL_USER=existing bash -eE "$ROOT/install/config/docker.sh"
 OMARCHY_INSTALL_USER=existing bash -eE "$ROOT/install/hardware/input-group.sh"
+OMARCHY_INSTALL_USER=existing bash -eE "$ROOT/install/config/browser-policy.sh"
 grep -qx -- "-aG input existing" "$TMPDIR/usermod.calls" || fail "usermod grants input to the install user"
+! grep -q -- "omarchy-browser-policy" "$TMPDIR/usermod.calls" ||
+  fail "usermod must not grant browser-policy to the install user"
 ! grep -q -- "docker" "$TMPDIR/usermod.calls" || fail "usermod must not grant docker to the install user"
-pass "existing install user gets input but never docker"
+pass "existing install user gets input but never docker or browser-policy"
diff --git a/test/shell.d/upgrade-to-quattro-test.sh b/test/shell.d/upgrade-to-quattro-test.sh
index bf94605f..60e8abff 100644
--- a/test/shell.d/upgrade-to-quattro-test.sh
+++ b/test/shell.d/upgrade-to-quattro-test.sh
@@ -67,6 +67,24 @@ grep -F 'OMARCHY_INSTALL_USER="$target_user"' "$upgrade_to_quattro" >/dev/null
 grep -F '"$apply_lock"' "$upgrade_to_quattro" >/dev/null
 pass "Omarchy 4 upgrade configures lock screen authentication for the target user"
 
+grep -F 'install/helpers/browser-policy.sh' "$upgrade_to_quattro" >/dev/null ||
+  fail "Omarchy 4 upgrade uses the shared browser-policy helper"
+grep -F 'as_root test -f "$browser_policy_helper"' "$upgrade_to_quattro" >/dev/null ||
+  fail "Omarchy 4 upgrade survives a packaged tree without the browser-policy helper"
+if grep -F 'browser_policy_setup_group' "$upgrade_to_quattro" >/dev/null; then
+  fail "Omarchy 4 upgrade does not create a browser-policy group"
+fi
+grep -F 'browser_policy_setup_dir /etc/chromium/policies/managed' "$upgrade_to_quattro" >/dev/null ||
+  fail "Omarchy 4 upgrade creates a root-owned Chromium policy directory"
+grep -F 'BROWSER_POLICY_MANAGED_DIRS' "$upgrade_to_quattro" >/dev/null ||
+  fail "Omarchy 4 upgrade hardens every Chromium-family policy directory"
+grep -F 'run_as_user_omarchy omarchy-theme-set-browser' "$upgrade_to_quattro" >/dev/null ||
+  fail "Omarchy 4 upgrade rewrites browser theme colour after a headless theme-set"
+if grep -E 'install -d -m 0?[27]?777 /etc/.*/policies|chmod a\+rw|2775' "$upgrade_to_quattro" >/dev/null; then
+  fail "Omarchy 4 upgrade does not create a world-writable Chromium policy directory"
+fi
+pass "Omarchy 4 upgrade locks the Chromium policy directory to root"
+
 grep -F 'OMARCHY_UPGRADE_TO_QUATTRO_LIVE=1' "$upgrade_to_quattro" >/dev/null
 grep -F 'systemd-networkd.service' "$upgrade_to_quattro" >/dev/null
 grep -F 'systemd-networkd.socket' "$upgrade_to_quattro" >/dev/null