refactor(install): detect the web service user in one function

first_time_install.sh pasted the same WEB_SERVICE_USER detection block
three times (Step 3.1's fallback, the plugin-repos setup and Step 11).
The copies were identical apart from comments; they now call
detect_web_service_user(), whose body is that block unchanged.

Behaviour is the same: the function sets the same global and always
returns 0, as the inline if-chain did. Checked on Linux against all
three original copies across 13 layouts (installed unit with and without
User=, the repo as shipped, each grep branch, template placeholders).

The comment notes that the install_web_service.sh / install_service.sh
greps no longer match anything, so until Step 8 installs the unit the
result is "root". That behaviour is left as it was.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/PLUGIN_DEPENDENCY_GUIDE.md

@@ -157,5 +157,6 @@ For more, see the [Plugin Dependency Troubleshooting Guide](PLUGIN_DEPENDENCY_TR
 - Store installs: `src/plugin_system/store_manager.py` (`_install_dependencies`)
 - Root install helper: `src/common/permission_utils.py` (`install_requirements_file`), `scripts/fix_perms/safe_pip_install.sh`
 - Load-time installs: `src/plugin_system/plugin_loader.py` (`install_dependencies`)
-- Sudo rules: `scripts/install/configure_web_sudo.sh`
+- Sudo rules: `scripts/install/lib_sudoers.sh` (written by `first_time_install.sh`
+  and `scripts/install/configure_web_sudo.sh`)
 - Manual installer: `scripts/install_plugin_dependencies.sh`

first_time_install.sh

@@ -502,6 +502,41 @@ print_rgbmatrix_build_failure() {
     fi
 }
 
+# Set WEB_SERVICE_USER to the account ledmatrix-web.service runs as, or "root"
+# when it cannot tell. Steps 3.1 and 11 choose plugin-directory ownership from
+# it. The logic was pasted three times, identically, and is kept verbatim here.
+# Note: install_web_service.sh and install_service.sh no longer contain the
+# "User=root" / "User=${ACTUAL_USER}" strings grepped for below (the units come
+# from systemd/*.service templates with User=__USER__), so until Step 8 has
+# installed the unit this yields "root".
+detect_web_service_user() {
+    WEB_SERVICE_USER="root"
+    if [ -f "/etc/systemd/system/ledmatrix-web.service" ]; then
+        # Check actual installed service file (most accurate)
+        WEB_SERVICE_USER=$(grep "^User=" /etc/systemd/system/ledmatrix-web.service | cut -d'=' -f2 || echo "root")
+    elif [ -f "$PROJECT_ROOT_DIR/scripts/install/install_web_service.sh" ]; then
+        # Check install_web_service.sh (used by first_time_install.sh)
+        if grep -q "User=root" "$PROJECT_ROOT_DIR/scripts/install/install_web_service.sh"; then
+            WEB_SERVICE_USER="root"
+        elif grep -q "User=\${ACTUAL_USER}" "$PROJECT_ROOT_DIR/scripts/install/install_web_service.sh"; then
+            WEB_SERVICE_USER="$ACTUAL_USER"
+        fi
+    elif [ -f "$PROJECT_ROOT_DIR/systemd/ledmatrix-web.service" ]; then
+        # Check template file (may have placeholder)
+        WEB_SERVICE_USER=$(grep "^User=" "$PROJECT_ROOT_DIR/systemd/ledmatrix-web.service" | cut -d'=' -f2 || echo "root")
+        # If template has placeholder, check install script
+        if [ "$WEB_SERVICE_USER" = "__USER__" ] || [ -z "$WEB_SERVICE_USER" ]; then
+            # Check install_service.sh to see what user it uses
+            if [ -f "$PROJECT_ROOT_DIR/scripts/install/install_service.sh" ] && grep -q "User=\${ACTUAL_USER}" "$PROJECT_ROOT_DIR/scripts/install/install_service.sh"; then
+                WEB_SERVICE_USER="$ACTUAL_USER"
+            fi
+        fi
+    elif [ -f "$PROJECT_ROOT_DIR/scripts/install/install_service.sh" ] && grep -q "User=\${ACTUAL_USER}" "$PROJECT_ROOT_DIR/scripts/install/install_service.sh"; then
+        # Web service will be installed by install_service.sh as ACTUAL_USER
+        WEB_SERVICE_USER="$ACTUAL_USER"
+    fi
+}
+
 echo ""
 echo "This script will perform the following steps:"
 echo "1. Check prerequisites (network, disk, memory) and install system dependencies"
@@ -699,32 +734,7 @@ else
     fi
     
     # Determine ownership based on web service user
-    # Check if web service file exists and what user it runs as
-    WEB_SERVICE_USER="root"
-    if [ -f "/etc/systemd/system/ledmatrix-web.service" ]; then
-        # Check actual installed service file (most accurate)
-        WEB_SERVICE_USER=$(grep "^User=" /etc/systemd/system/ledmatrix-web.service | cut -d'=' -f2 || echo "root")
-    elif [ -f "$PROJECT_ROOT_DIR/scripts/install/install_web_service.sh" ]; then
-        # Check install_web_service.sh (used by first_time_install.sh)
-        if grep -q "User=root" "$PROJECT_ROOT_DIR/scripts/install/install_web_service.sh"; then
-            WEB_SERVICE_USER="root"
-        elif grep -q "User=\${ACTUAL_USER}" "$PROJECT_ROOT_DIR/scripts/install/install_web_service.sh"; then
-            WEB_SERVICE_USER="$ACTUAL_USER"
-        fi
-    elif [ -f "$PROJECT_ROOT_DIR/systemd/ledmatrix-web.service" ]; then
-        # Check template file (may have placeholder)
-        WEB_SERVICE_USER=$(grep "^User=" "$PROJECT_ROOT_DIR/systemd/ledmatrix-web.service" | cut -d'=' -f2 || echo "root")
-        # If template has placeholder, check install script
-        if [ "$WEB_SERVICE_USER" = "__USER__" ] || [ -z "$WEB_SERVICE_USER" ]; then
-            # Check install_service.sh to see what user it uses
-            if [ -f "$PROJECT_ROOT_DIR/scripts/install/install_service.sh" ] && grep -q "User=\${ACTUAL_USER}" "$PROJECT_ROOT_DIR/scripts/install/install_service.sh"; then
-                WEB_SERVICE_USER="$ACTUAL_USER"
-            fi
-        fi
-    elif [ -f "$PROJECT_ROOT_DIR/scripts/install/install_service.sh" ] && grep -q "User=\${ACTUAL_USER}" "$PROJECT_ROOT_DIR/scripts/install/install_service.sh"; then
-        # Web service will be installed by install_service.sh as ACTUAL_USER
-        WEB_SERVICE_USER="$ACTUAL_USER"
-    fi
+    detect_web_service_user
     
     # If web service runs as ACTUAL_USER (not root), set ownership to ACTUAL_USER
     # so the web service can change permissions. Root service can still access via group (775).
@@ -758,32 +768,7 @@ if [ ! -d "$PLUGIN_REPOS_DIR" ]; then
 fi
 
 # Determine ownership based on web service user
-# Check if web service file exists and what user it runs as
-WEB_SERVICE_USER="root"
-if [ -f "/etc/systemd/system/ledmatrix-web.service" ]; then
-    # Check actual installed service file (most accurate)
-    WEB_SERVICE_USER=$(grep "^User=" /etc/systemd/system/ledmatrix-web.service | cut -d'=' -f2 || echo "root")
-elif [ -f "$PROJECT_ROOT_DIR/scripts/install/install_web_service.sh" ]; then
-    # Check install_web_service.sh (used by first_time_install.sh)
-    if grep -q "User=root" "$PROJECT_ROOT_DIR/scripts/install/install_web_service.sh"; then
-        WEB_SERVICE_USER="root"
-    elif grep -q "User=\${ACTUAL_USER}" "$PROJECT_ROOT_DIR/scripts/install/install_web_service.sh"; then
-        WEB_SERVICE_USER="$ACTUAL_USER"
-    fi
-elif [ -f "$PROJECT_ROOT_DIR/systemd/ledmatrix-web.service" ]; then
-    # Check template file (may have placeholder)
-    WEB_SERVICE_USER=$(grep "^User=" "$PROJECT_ROOT_DIR/systemd/ledmatrix-web.service" | cut -d'=' -f2 || echo "root")
-    # If template has placeholder, check install script
-    if [ "$WEB_SERVICE_USER" = "__USER__" ] || [ -z "$WEB_SERVICE_USER" ]; then
-        # Check install_service.sh to see what user it uses
-        if [ -f "$PROJECT_ROOT_DIR/scripts/install/install_service.sh" ] && grep -q "User=\${ACTUAL_USER}" "$PROJECT_ROOT_DIR/scripts/install/install_service.sh"; then
-            WEB_SERVICE_USER="$ACTUAL_USER"
-        fi
-    fi
-elif [ -f "$PROJECT_ROOT_DIR/scripts/install/install_service.sh" ] && grep -q "User=\${ACTUAL_USER}" "$PROJECT_ROOT_DIR/scripts/install/install_service.sh"; then
-    # Web service will be installed by install_service.sh as ACTUAL_USER
-    WEB_SERVICE_USER="$ACTUAL_USER"
-fi
+detect_web_service_user
 
 # If web service runs as ACTUAL_USER (not root), set ownership to ACTUAL_USER
 # so the web service can change permissions. Root service can still access via group (775).
@@ -1516,51 +1501,31 @@ POWEROFF_PATH=$(which poweroff)
 BASH_PATH=$(which bash)
 JOURNALCTL_PATH=$(which journalctl 2>/dev/null || true)
 
-# Create sudoers content
-cat > "$SUDOERS_TMP" << EOF
-# LED Matrix Web Interface passwordless sudo configuration
-# This allows the web interface user to run specific commands without a password
-
-# Allow $ACTUAL_USER to run specific commands without a password for the LED Matrix web interface
-$ACTUAL_USER ALL=(ALL) NOPASSWD: $REBOOT_PATH
-$ACTUAL_USER ALL=(ALL) NOPASSWD: $POWEROFF_PATH
-$ACTUAL_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH start ledmatrix.service
-$ACTUAL_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH stop ledmatrix.service
-$ACTUAL_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH restart ledmatrix.service
-$ACTUAL_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH enable ledmatrix.service
-$ACTUAL_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH disable ledmatrix.service
-$ACTUAL_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH status ledmatrix.service
-$ACTUAL_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH is-active ledmatrix
-$ACTUAL_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH is-active ledmatrix.service
-$ACTUAL_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH start ledmatrix-web.service
-$ACTUAL_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH stop ledmatrix-web.service
-$ACTUAL_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH restart ledmatrix-web.service
-$ACTUAL_USER ALL=(ALL) NOPASSWD: $BASH_PATH $PROJECT_ROOT_DIR/scripts/fix_perms/safe_plugin_rm.sh *
-# Install a requirements.txt as root via vetted helper, so packages are visible
-# to root-run ledmatrix.service (not just the web interface's own user).
-$ACTUAL_USER ALL=(ALL) NOPASSWD: $BASH_PATH $PROJECT_ROOT_DIR/scripts/fix_perms/safe_pip_install.sh *
-EOF
-if [ -n "$JOURNALCTL_PATH" ]; then
-    cat >> "$SUDOERS_TMP" << EOF
-# NOEXEC, because these rules end in a wildcard and journalctl starts a pager
-# when its output is a terminal. From that pager (less) a "!sh" is a root
-# shell -- the standard journalctl escalation. The web interface always passes
-# --no-pager, so nothing here needs it, but the rule cannot require a flag that
-# sits in the middle of the command line. NOEXEC stops the command executing
-# another program at all, which closes the hole without depending on wildcard
-# matching subtleties.
-$ACTUAL_USER ALL=(ALL) NOPASSWD:NOEXEC: $JOURNALCTL_PATH -u ledmatrix.service *
-$ACTUAL_USER ALL=(ALL) NOPASSWD:NOEXEC: $JOURNALCTL_PATH -u ledmatrix *
-$ACTUAL_USER ALL=(ALL) NOPASSWD:NOEXEC: $JOURNALCTL_PATH -t ledmatrix *
-EOF
+# The rules themselves live in scripts/install/lib_sudoers.sh, shared with
+# scripts/install/configure_web_sudo.sh so the two cannot drift apart again.
+# If it is missing (a damaged checkout), keep whatever is already installed
+# rather than failing the whole install; the gate below skips the install.
+SUDOERS_VALID=1
+SUDOERS_LIB="$PROJECT_ROOT_DIR/scripts/install/lib_sudoers.sh"
+if [ -f "$SUDOERS_LIB" ]; then
+    # shellcheck source=scripts/install/lib_sudoers.sh
+    . "$SUDOERS_LIB"
+    web_sudoers_rules "$ACTUAL_USER" "$PROJECT_ROOT_DIR" "$SYSTEMCTL_PATH" "$BASH_PATH" \
+        "$REBOOT_PATH" "$POWEROFF_PATH" "$JOURNALCTL_PATH" > "$SUDOERS_TMP"
+else
+    SUDOERS_VALID=0
+    echo "⚠ $SUDOERS_LIB not found; cannot generate the sudoers rules." >&2
+    echo "⚠ Leaving $SUDOERS_FILE unchanged. The web interface cannot control" >&2
+    echo "  the display service until this is fixed." >&2
 fi
 
 # Never install rules we have not parsed. A malformed drop-in in
 # /etc/sudoers.d makes sudo refuse every command for every user, which on a
 # headless Pi leaves no way in at all. If the rules do not parse, say so and
 # keep whatever is already installed.
-SUDOERS_VALID=1
-if command -v visudo >/dev/null 2>&1; then
+if [ "$SUDOERS_VALID" = "0" ]; then
+    :  # nothing was generated; already reported above
+elif command -v visudo >/dev/null 2>&1; then
     if ! visudo -c -f "$SUDOERS_TMP" >/dev/null 2>&1; then
         SUDOERS_VALID=0
         echo "⚠ The generated sudoers rules did not parse:" >&2
@@ -1690,28 +1655,8 @@ fi
 
 # Re-apply plugin directory permissions based on web service user
 echo "Re-applying plugin directory permissions..."
-# Determine web service user (check installed service, install scripts, or template)
-WEB_SERVICE_USER="root"
-if [ -f "/etc/systemd/system/ledmatrix-web.service" ]; then
-    # Check actual installed service file (most accurate)
-    WEB_SERVICE_USER=$(grep "^User=" /etc/systemd/system/ledmatrix-web.service | cut -d'=' -f2 || echo "root")
-elif [ -f "$PROJECT_ROOT_DIR/scripts/install/install_web_service.sh" ]; then
-    # Check install_web_service.sh (used by first_time_install.sh)
-    if grep -q "User=root" "$PROJECT_ROOT_DIR/scripts/install/install_web_service.sh"; then
-        WEB_SERVICE_USER="root"
-    elif grep -q "User=\${ACTUAL_USER}" "$PROJECT_ROOT_DIR/scripts/install/install_web_service.sh"; then
-        WEB_SERVICE_USER="$ACTUAL_USER"
-    fi
-elif [ -f "$PROJECT_ROOT_DIR/systemd/ledmatrix-web.service" ]; then
-    WEB_SERVICE_USER=$(grep "^User=" "$PROJECT_ROOT_DIR/systemd/ledmatrix-web.service" | cut -d'=' -f2 || echo "root")
-    if [ "$WEB_SERVICE_USER" = "__USER__" ] || [ -z "$WEB_SERVICE_USER" ]; then
-        if [ -f "$PROJECT_ROOT_DIR/scripts/install/install_service.sh" ] && grep -q "User=\${ACTUAL_USER}" "$PROJECT_ROOT_DIR/scripts/install/install_service.sh"; then
-            WEB_SERVICE_USER="$ACTUAL_USER"
-        fi
-    fi
-elif [ -f "$PROJECT_ROOT_DIR/scripts/install/install_service.sh" ] && grep -q "User=\${ACTUAL_USER}" "$PROJECT_ROOT_DIR/scripts/install/install_service.sh"; then
-    WEB_SERVICE_USER="$ACTUAL_USER"
-fi
+# Determine ownership based on web service user
+detect_web_service_user
 
 # Set ownership based on web service user
 if [ "$WEB_SERVICE_USER" = "$ACTUAL_USER" ] || [ "$WEB_SERVICE_USER" != "root" ]; then

scripts/install/configure_web_sudo.sh

@@ -59,6 +59,16 @@ if [ ! -f "$SAFE_PIP_INSTALL_PATH" ]; then
     exit 1
 fi
 
+# The rules are shared with first_time_install.sh (Step 10) so the two cannot
+# drift apart; add or remove a grant in lib_sudoers.sh, not here.
+SUDOERS_LIB="$PROJECT_DIR/lib_sudoers.sh"
+if [ ! -f "$SUDOERS_LIB" ]; then
+    echo "Error: Sudoers rules library not found: $SUDOERS_LIB" >&2
+    exit 1
+fi
+# shellcheck source=scripts/install/lib_sudoers.sh
+. "$SUDOERS_LIB"
+
 echo "Command paths:"
 echo "  Python: $PYTHON_PATH"
 echo "  Systemctl: $SYSTEMCTL_PATH"
@@ -72,56 +82,8 @@ echo "  Safe pip install: $SAFE_PIP_INSTALL_PATH"
 # Create a temporary sudoers file
 TEMP_SUDOERS="/tmp/ledmatrix_web_sudoers_$$"
 
-{
-    echo "# LED Matrix Web Interface passwordless sudo configuration"
-    echo "# This allows the web interface user to run specific commands without a password"
-    echo ""
-    echo "# Allow $WEB_USER to run specific commands without a password for the LED Matrix web interface"
-
-    # Optional: reboot/poweroff (non-critical — skip if not found)
-    if [ -n "$REBOOT_PATH" ]; then
-        echo "$WEB_USER ALL=(ALL) NOPASSWD: $REBOOT_PATH"
-    fi
-    if [ -n "$POWEROFF_PATH" ]; then
-        echo "$WEB_USER ALL=(ALL) NOPASSWD: $POWEROFF_PATH"
-    fi
-
-    # Required: systemctl
-    echo "$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH start ledmatrix.service"
-    echo "$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH stop ledmatrix.service"
-    echo "$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH restart ledmatrix.service"
-    echo "$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH enable ledmatrix.service"
-    echo "$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH disable ledmatrix.service"
-    echo "$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH status ledmatrix.service"
-    echo "$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH is-active ledmatrix"
-    echo "$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH is-active ledmatrix.service"
-    echo "$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH start ledmatrix-web.service"
-    echo "$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH stop ledmatrix-web.service"
-    echo "$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH restart ledmatrix-web.service"
-
-    # Optional: journalctl (non-critical — skip if not found)
-    #
-    # NOEXEC, matching first_time_install.sh. These rules end in a wildcard and
-    # journalctl starts a pager, so without it the caller can reach a shell:
-    # less runs "!command" as the user the pager belongs to, which here is
-    # root. NOEXEC stops the granted command executing anything of its own.
-    if [ -n "$JOURNALCTL_PATH" ]; then
-        echo "$WEB_USER ALL=(ALL) NOPASSWD:NOEXEC: $JOURNALCTL_PATH -u ledmatrix.service *"
-        echo "$WEB_USER ALL=(ALL) NOPASSWD:NOEXEC: $JOURNALCTL_PATH -u ledmatrix *"
-        echo "$WEB_USER ALL=(ALL) NOPASSWD:NOEXEC: $JOURNALCTL_PATH -t ledmatrix *"
-    fi
-
-    echo ""
-    echo "# Allow web user to remove plugin directories via vetted helper script"
-    echo "# The helper validates that the target path resolves inside plugin-repos/ or plugins/"
-    echo "$WEB_USER ALL=(ALL) NOPASSWD: $BASH_PATH $SAFE_RM_PATH *"
-    echo ""
-    echo "# Allow web user to install a plugin's requirements.txt as root via vetted"
-    echo "# helper script, so packages are visible to root-run ledmatrix.service"
-    echo "# (not just the web interface's own user). The helper validates the target"
-    echo "# is requirements.txt at the project root or under plugin-repos/ or plugins/."
-    echo "$WEB_USER ALL=(ALL) NOPASSWD: $BASH_PATH $SAFE_PIP_INSTALL_PATH *"
-} > "$TEMP_SUDOERS"
+web_sudoers_rules "$WEB_USER" "$PROJECT_ROOT" "$SYSTEMCTL_PATH" "$BASH_PATH" \
+    "$REBOOT_PATH" "$POWEROFF_PATH" "$JOURNALCTL_PATH" > "$TEMP_SUDOERS"
 
 # Never offer to install rules we have not parsed. A malformed drop-in in
 # /etc/sudoers.d makes sudo refuse every command for every user.

scripts/install/lib_sudoers.sh

@@ -0,0 +1,76 @@
+#!/bin/bash
+#
+# The web interface's passwordless-sudo allow-list, /etc/sudoers.d/ledmatrix_web.
+#
+# Sourced by first_time_install.sh (Step 10) and
+# scripts/install/configure_web_sudo.sh. Both used to carry their own copy of
+# these rules, and the copies drifted: one granted safe_pip_install.sh and the
+# other did not. Each caller still owns its own validate (visudo -c) / install /
+# confirm flow; this file only prints the rules.
+#
+# Add or remove a grant here and nowhere else.
+
+# web_sudoers_rules WEB_USER PROJECT_ROOT SYSTEMCTL_PATH BASH_PATH REBOOT_PATH POWEROFF_PATH JOURNALCTL_PATH
+#
+# Print the ledmatrix_web sudoers rules to stdout.
+#
+# SYSTEMCTL_PATH and BASH_PATH are required, and the caller must make sure they
+# are not empty: `visudo -c` does not catch every such rule (with an empty
+# BASH_PATH the helper rules still parse, granting the script itself).
+# first_time_install.sh stops on a failed `which`; configure_web_sudo.sh checks
+# them before calling this.
+# REBOOT_PATH, POWEROFF_PATH and JOURNALCTL_PATH are optional: pass "" and
+# their rules are left out.
+web_sudoers_rules() {
+    local WEB_USER="${1:-}"
+    local PROJECT_ROOT="${2:-}"
+    local SYSTEMCTL_PATH="${3:-}"
+    local BASH_PATH="${4:-}"
+    local REBOOT_PATH="${5:-}"
+    local POWEROFF_PATH="${6:-}"
+    local JOURNALCTL_PATH="${7:-}"
+
+    cat << EOF
+# LED Matrix Web Interface passwordless sudo configuration
+# This allows the web interface user to run specific commands without a password
+
+# Allow $WEB_USER to run specific commands without a password for the LED Matrix web interface
+EOF
+    if [ -n "$REBOOT_PATH" ]; then
+        printf '%s\n' "$WEB_USER ALL=(ALL) NOPASSWD: $REBOOT_PATH"
+    fi
+    if [ -n "$POWEROFF_PATH" ]; then
+        printf '%s\n' "$WEB_USER ALL=(ALL) NOPASSWD: $POWEROFF_PATH"
+    fi
+    cat << EOF
+$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH start ledmatrix.service
+$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH stop ledmatrix.service
+$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH restart ledmatrix.service
+$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH enable ledmatrix.service
+$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH disable ledmatrix.service
+$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH status ledmatrix.service
+$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH is-active ledmatrix
+$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH is-active ledmatrix.service
+$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH start ledmatrix-web.service
+$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH stop ledmatrix-web.service
+$WEB_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH restart ledmatrix-web.service
+$WEB_USER ALL=(ALL) NOPASSWD: $BASH_PATH $PROJECT_ROOT/scripts/fix_perms/safe_plugin_rm.sh *
+# Install a requirements.txt as root via vetted helper, so packages are visible
+# to root-run ledmatrix.service (not just the web interface's own user).
+$WEB_USER ALL=(ALL) NOPASSWD: $BASH_PATH $PROJECT_ROOT/scripts/fix_perms/safe_pip_install.sh *
+EOF
+    if [ -n "$JOURNALCTL_PATH" ]; then
+        cat << EOF
+# NOEXEC, because these rules end in a wildcard and journalctl starts a pager
+# when its output is a terminal. From that pager (less) a "!sh" is a root
+# shell -- the standard journalctl escalation. The web interface always passes
+# --no-pager, so nothing here needs it, but the rule cannot require a flag that
+# sits in the middle of the command line. NOEXEC stops the command executing
+# another program at all, which closes the hole without depending on wildcard
+# matching subtleties.
+$WEB_USER ALL=(ALL) NOPASSWD:NOEXEC: $JOURNALCTL_PATH -u ledmatrix.service *
+$WEB_USER ALL=(ALL) NOPASSWD:NOEXEC: $JOURNALCTL_PATH -u ledmatrix *
+$WEB_USER ALL=(ALL) NOPASSWD:NOEXEC: $JOURNALCTL_PATH -t ledmatrix *
+EOF
+    fi
+}

test/test_auto_update_verify.py

@@ -320,5 +320,6 @@ def test_units_installers_and_updater_agree():
         assert (f'systemd/{unit}', f'/etc/systemd/system/{unit}') in StartupValidator._UNITS
 
     # Triggering takes no privilege any more; no sudoers rule should linger.
-    for sudoers in ('scripts/install/configure_web_sudo.sh', 'first_time_install.sh'):
+    for sudoers in ('scripts/install/configure_web_sudo.sh', 'first_time_install.sh',
+                    'scripts/install/lib_sudoers.sh'):
         assert not re.search(r'NOPASSWD:.*update-verify', (ROOT / sudoers).read_text(encoding='utf-8')), sudoers

test/test_sudo_allowlist_covers_calls.py

@@ -37,6 +37,9 @@ ROOT = Path(__file__).resolve().parent.parent
 INSTALLERS = (
     ROOT / "first_time_install.sh",
     ROOT / "scripts" / "install" / "configure_wifi_permissions.sh",
+    # The ledmatrix_web rules, which first_time_install.sh and
+    # configure_web_sudo.sh both take from here.
+    ROOT / "scripts" / "install" / "lib_sudoers.sh",
 )
 
 #: Commands this change grants, each fully literal in the source.

test/test_sudoers_is_validated.py

@@ -62,33 +62,135 @@ def test_configure_web_sudo_validates_before_installing():
     assert validate < install, "the rules must be checked before they are installed"
 
 
-def _render_first_time_sudoers(project_root, user):
-    """Run the installer's own sudoers heredoc with realistic values."""
+def test_a_missing_rules_library_installs_nothing():
+    """If lib_sudoers.sh is missing, nothing is generated -- and an empty file
+    would pass `visudo -c` -- so that branch must set the flag the install is
+    gated on."""
     body = _read(FIRST_TIME)
-    start = body.index("# Create sudoers content")
+    missing = body.index('if [ -f "$SUDOERS_LIB" ]; then')
+    flagged = body.index("SUDOERS_VALID=0", missing)
+    validate = body.index('visudo -c -f "$SUDOERS_TMP"')
+    install = body.index('cp "$SUDOERS_TMP" "$SUDOERS_FILE"')
+    gate = body.rindex('if [ "$SUDOERS_VALID" = "0" ]; then', 0, install)
+    assert missing < flagged < validate < gate < install
+
+
+def _step10_generation(body):
+    """first_time_install.sh's own Step 10 code that writes $SUDOERS_TMP."""
+    start = body.index("# The rules themselves live in scripts/install/lib_sudoers.sh")
     end = body.index("# Never install rules we have not parsed.")
-    block = body[start:end]
-    out = os.path.join(project_root, "rendered")
+    return body[start:end]
+
+
+def _run_step10_generation(project_root, user, out):
+    """Run the installer's Step 10 generation with realistic values.
+
+    Returns the SUDOERS_VALID it leaves behind."""
     script = "\n".join(
         [
-            "set -euo pipefail",
+            "set -Eeuo pipefail",
             f"ACTUAL_USER={user}",
-            f"PROJECT_ROOT_DIR={project_root}",
-            'SUDOERS_TMP="$(mktemp)"',
-            "PYTHON_PATH=$(which python3)",
+            f"PROJECT_ROOT_DIR='{project_root}'",
+            f"SUDOERS_TMP='{out}'",
+            "SUDOERS_FILE=/etc/sudoers.d/ledmatrix_web",
             "SYSTEMCTL_PATH=/usr/bin/systemctl",
             "REBOOT_PATH=/usr/sbin/reboot",
             "POWEROFF_PATH=/usr/sbin/poweroff",
             "BASH_PATH=$(which bash)",
             "JOURNALCTL_PATH=/usr/bin/journalctl",
-            block,
-            f'cp "$SUDOERS_TMP" {out}',
+            _step10_generation(_read(FIRST_TIME)),
+            'printf %s "$SUDOERS_VALID"',
         ]
     )
-    subprocess.run(["bash", "-c", script], check=True)
+    return subprocess.run(
+        ["bash", "-c", script], check=True, capture_output=True, text=True
+    ).stdout
+
+
+def _render_first_time_sudoers(tmp, user):
+    """The rules first_time_install.sh generates, via the shared library."""
+    out = os.path.join(tmp, "rendered")
+    assert _run_step10_generation(REPO_ROOT, user, out) == "1"
     return out
 
 
+def _run_step10(tmp, project_root, visudo_ok, existing=None):
+    """Run all of Step 10 against a sudoers file in `tmp`, never /etc.
+
+    systemctl, reboot, poweroff, journalctl and visudo are stubs, so the
+    outcome does not depend on the machine running the test."""
+    body = _read(FIRST_TIME)
+    step = body[body.index('CURRENT_STEP="Configure passwordless sudo access"'):
+                body.index('CURRENT_STEP="Configure WiFi management permissions"')]
+    target = os.path.join(tmp, "ledmatrix_web")
+    real = 'SUDOERS_FILE="/etc/sudoers.d/ledmatrix_web"'
+    assert step.count(real) == 1
+    step = step.replace(real, f"SUDOERS_FILE='{target}'")
+    stubs = os.path.join(tmp, "stubs")
+    os.mkdir(stubs)
+    for name, code in (("systemctl", 0), ("reboot", 0), ("poweroff", 0),
+                       ("journalctl", 0), ("visudo", 0 if visudo_ok else 1)):
+        path = os.path.join(stubs, name)
+        with open(path, "w", encoding="utf-8") as handle:
+            handle.write(f"#!/bin/sh\nexit {code}\n")
+        os.chmod(path, 0o755)
+    if existing is not None:
+        with open(target, "w", encoding="utf-8") as handle:
+            handle.write(existing)
+    env = dict(os.environ, TMPDIR=tmp,
+               PATH=os.pathsep.join([stubs, os.path.dirname(sys.executable),
+                                     "/usr/bin", "/bin"]))
+    script = "\n".join(["set -Eeuo pipefail", "ACTUAL_USER=ledmatrix",
+                          f"PROJECT_ROOT_DIR='{project_root}'", step])
+    result = subprocess.run(["bash", "-c", script], env=env,
+                            capture_output=True, text=True)
+    assert result.returncode == 0, result.stdout + result.stderr
+    return target, stubs, result
+
+
+_POSIX_STEP10 = pytest.mark.skipif(
+    sys.platform == "win32" or shutil.which("which") is None,
+    reason="needs a POSIX bash and which")
+
+
+@_POSIX_STEP10
+def test_step10_installs_the_generated_rules():
+    with tempfile.TemporaryDirectory() as tmp:
+        target, stubs, _ = _run_step10(tmp, REPO_ROOT, visudo_ok=True)
+        assert oct(os.stat(target).st_mode & 0o777) == "0o440"
+        with open(target, encoding="utf-8") as handle:
+            installed = handle.read()
+        lib = os.path.join(REPO_ROOT, "scripts", "install", "lib_sudoers.sh")
+        expected = subprocess.run(
+            ["bash", "-c", '. "$1"; web_sudoers_rules ledmatrix "$2" "$3/systemctl" '
+             '"$(command -v bash)" "$3/reboot" "$3/poweroff" "$3/journalctl"',
+             "_", lib, REPO_ROOT, stubs],
+            check=True, capture_output=True, text=True,
+            env=dict(os.environ, PATH=os.pathsep.join([stubs, "/usr/bin", "/bin"])),
+        ).stdout
+        assert installed == expected
+        assert not [f for f in os.listdir(tmp) if f.startswith("ledmatrix_web_sudoers.")]
+
+
+@_POSIX_STEP10
+def test_step10_without_the_library_keeps_the_existing_file():
+    with tempfile.TemporaryDirectory() as tmp:
+        target, _, result = _run_step10(tmp, tmp, visudo_ok=True, existing="keep\n")
+        with open(target, encoding="utf-8") as handle:
+            assert handle.read() == "keep\n"
+        assert "lib_sudoers.sh not found" in result.stderr
+        assert "Passwordless sudo access configured" not in result.stdout
+
+
+@_POSIX_STEP10
+def test_step10_keeps_the_existing_file_when_the_rules_do_not_parse():
+    with tempfile.TemporaryDirectory() as tmp:
+        target, _, result = _run_step10(tmp, REPO_ROOT, visudo_ok=False, existing="keep\n")
+        with open(target, encoding="utf-8") as handle:
+            assert handle.read() == "keep\n"
+        assert "did not parse" in result.stderr
+
+
 @pytest.mark.skipif(sys.platform == "win32", reason="visudo is POSIX only")
 @pytest.mark.skipif(VISUDO is None, reason="visudo not installed")
 def test_the_rules_the_installer_emits_actually_parse():

test/test_sudoers_noexec_on_pagers.py

@@ -30,10 +30,14 @@ ROOT = Path(__file__).resolve().parent.parent
 INSTALLERS = (
     ROOT / "first_time_install.sh",
     ROOT / "scripts" / "install" / "configure_wifi_permissions.sh",
-    # Writes the same journalctl grants as first_time_install.sh. It was
-    # missing here, and because of that this suite passed while three
-    # ungranted wildcard rules sat in it.
+    # Used to write its own copy of the journalctl grants. It was missing
+    # here, and because of that this suite passed while three untagged
+    # wildcard rules sat in it. Both it and first_time_install.sh now take
+    # their rules from lib_sudoers.sh; they stay listed so a rule written
+    # directly into either one is still checked.
     ROOT / "scripts" / "install" / "configure_web_sudo.sh",
+    # The ledmatrix_web rules, shared by both installers.
+    ROOT / "scripts" / "install" / "lib_sudoers.sh",
 )
 
 #: Commands that will start another program of their own accord -- a pager, an

test/test_web_sudoers_installers_agree.py

@@ -1,53 +1,189 @@
-"""The two installers that write /etc/sudoers.d/ledmatrix_web must agree.
+"""One generator writes /etc/sudoers.d/ledmatrix_web, and both installers use it.
 
-first_time_install.sh (Step 10, a heredoc) and scripts/install/configure_web_sudo.sh
-(a block of echo lines) each generate the web user's sudo allow-list. They
-drifted: configure_web_sudo.sh granted scripts/fix_perms/safe_pip_install.sh
-but first_time_install.sh did not, so on a device set up only by the first-time
+first_time_install.sh (Step 10) and scripts/install/configure_web_sudo.sh each
+used to carry their own copy of the web user's sudo allow-list -- a heredoc in
+one, a block of echo lines in the other -- and the copies drifted:
+configure_web_sudo.sh granted scripts/fix_perms/safe_pip_install.sh but
+first_time_install.sh did not, so on a device set up only by the first-time
 installer permission_utils.install_requirements_file could not use the root
 wrapper and fell back to a user-level install that root-run ledmatrix.service
 may not see (and the auto-update rollback reported its reinstall as failed).
 
-This compares the granted command sets after normalising the spellings that
-differ between the files but expand identically at install time:
-$WEB_USER/$ACTUAL_USER, $PROJECT_ROOT/$PROJECT_ROOT_DIR, and the helper-path
-variables configure_web_sudo.sh defines ($SAFE_RM_PATH, ...).
+The rules now live once, in web_sudoers_rules() in
+scripts/install/lib_sudoers.sh. What keeps them from drifting again:
+
+* neither installer writes a rule line of its own, and each writes the
+  generator's output to the very file it then validates and installs;
+* each passes its variables to the generator in the right positions -- checked
+  by running the installer's own call line with distinct values;
+* the generator's grants are pinned to an explicit list below, so dropping,
+  adding or re-pathing a grant is a deliberate edit to this file.
 
 It also checks that every fix_perms helper granted via sudo is hardened to
-root:root in both scripts -- and, in first_time_install.sh, after Step 11's
+root:root in both installers -- and, in first_time_install.sh, after Step 11's
 project-wide chown to the user, which would otherwise undo it.
 """
 import re
+import shutil
+import subprocess
+import sys
 from pathlib import Path
 
+import pytest
+
 ROOT = Path(__file__).resolve().parent.parent
 FIRST_TIME = ROOT / "first_time_install.sh"
 CONFIGURE = ROOT / "scripts" / "install" / "configure_web_sudo.sh"
+LIB = ROOT / "scripts" / "install" / "lib_sudoers.sh"
 
-#: Grants that intentionally exist in only one installer, as normalised
-#: commands. There are none today; add one here with a reason rather than
-#: loosening the comparison.
-ONLY_IN_FIRST_TIME = frozenset()
-ONLY_IN_CONFIGURE = frozenset()
+#: Every grant web_sudoers_rules() writes, as (tags, command) with the
+#: generator's own variable names. Changing the allow-list means changing this.
+EXPECTED_GRANTS = frozenset({
+    ("NOPASSWD:", "$REBOOT_PATH"),
+    ("NOPASSWD:", "$POWEROFF_PATH"),
+    ("NOPASSWD:", "$SYSTEMCTL_PATH start ledmatrix.service"),
+    ("NOPASSWD:", "$SYSTEMCTL_PATH stop ledmatrix.service"),
+    ("NOPASSWD:", "$SYSTEMCTL_PATH restart ledmatrix.service"),
+    ("NOPASSWD:", "$SYSTEMCTL_PATH enable ledmatrix.service"),
+    ("NOPASSWD:", "$SYSTEMCTL_PATH disable ledmatrix.service"),
+    ("NOPASSWD:", "$SYSTEMCTL_PATH status ledmatrix.service"),
+    ("NOPASSWD:", "$SYSTEMCTL_PATH is-active ledmatrix"),
+    ("NOPASSWD:", "$SYSTEMCTL_PATH is-active ledmatrix.service"),
+    ("NOPASSWD:", "$SYSTEMCTL_PATH start ledmatrix-web.service"),
+    ("NOPASSWD:", "$SYSTEMCTL_PATH stop ledmatrix-web.service"),
+    ("NOPASSWD:", "$SYSTEMCTL_PATH restart ledmatrix-web.service"),
+    ("NOPASSWD:", "$BASH_PATH $PROJECT_ROOT/scripts/fix_perms/safe_plugin_rm.sh *"),
+    ("NOPASSWD:", "$BASH_PATH $PROJECT_ROOT/scripts/fix_perms/safe_pip_install.sh *"),
+    ("NOPASSWD:NOEXEC:", "$JOURNALCTL_PATH -u ledmatrix.service *"),
+    ("NOPASSWD:NOEXEC:", "$JOURNALCTL_PATH -u ledmatrix *"),
+    ("NOPASSWD:NOEXEC:", "$JOURNALCTL_PATH -t ledmatrix *"),
+})
+
+#: The call each installer makes: its own names for the generator's arguments,
+#: in order, and the file it writes the rules to.
+CALLERS = {
+    FIRST_TIME: (("$ACTUAL_USER", "$PROJECT_ROOT_DIR", "$SYSTEMCTL_PATH", "$BASH_PATH",
+                  "$REBOOT_PATH", "$POWEROFF_PATH", "$JOURNALCTL_PATH"), "$SUDOERS_TMP"),
+    CONFIGURE: (("$WEB_USER", "$PROJECT_ROOT", "$SYSTEMCTL_PATH", "$BASH_PATH",
+                 "$REBOOT_PATH", "$POWEROFF_PATH", "$JOURNALCTL_PATH"), "$TEMP_SUDOERS"),
+}
+
+RULE = re.compile(r'(\S+) ALL=\(ALL\) (NOPASSWD:(?:NOEXEC:)?)\s*(.*?)"?$')
 
 
 def _text(path):
-    return path.read_text(encoding="utf-8", errors="replace")
+    return path.read_text(encoding="utf-8", errors="replace").replace("\r\n", "\n")
 
 
-def _web_sudoers_section(path):
-    """The part of the script that writes the ledmatrix_web allow-list.
+def _generator_grants():
+    """{(tags, command)} for every rule line in lib_sudoers.sh."""
+    grants = set()
+    for line in _text(LIB).splitlines():
+        m = RULE.search(line.strip())
+        if m and m.group(1).endswith("$WEB_USER"):
+            grants.add((m.group(2), " ".join(m.group(3).split())))
+    return grants
 
-    first_time_install.sh also writes other files later (WiFi permissions are
-    delegated to a separate script, but keep this robust against future
-    additions), so restrict it to Step 10.
-    """
+
+def _call(path):
+    """The installer's web_sudoers_rules statement, continuation lines joined."""
     text = _text(path)
-    if path == FIRST_TIME:
-        start = text.index('CURRENT_STEP="Configure passwordless sudo access"')
-        end = text.index('CURRENT_STEP="Configure WiFi management permissions"')
-        return text[start:end]
-    return text
+    calls = re.findall(r"^[ \t]*web_sudoers_rules\b(?:[^\n]*\\\n)*[^\n]*$", text, re.M)
+    assert len(calls) == 1, f"{path.name}: expected one web_sudoers_rules call, found {calls}"
+    return calls[0]
+
+
+def test_generator_grants_exactly_the_expected_rules():
+    grants = _generator_grants()
+    assert grants == EXPECTED_GRANTS, (
+        f"lib_sudoers.sh grants changed:\n  added: {sorted(grants - EXPECTED_GRANTS)}\n"
+        f"  removed: {sorted(EXPECTED_GRANTS - grants)}")
+
+
+@pytest.mark.parametrize("installer", [FIRST_TIME, CONFIGURE], ids=lambda p: p.name)
+def test_installer_writes_no_rules_of_its_own(installer):
+    """A rule added to one installer only is how they drifted last time."""
+    own = [line for line in _text(installer).splitlines()
+           if "NOPASSWD" in line and not line.lstrip().startswith("#")]
+    assert not own, f"{installer.name} writes sudoers rules itself: {own}"
+
+
+@pytest.mark.parametrize("installer", [FIRST_TIME, CONFIGURE], ids=lambda p: p.name)
+def test_installer_sources_the_generator_and_writes_what_it_validates(installer):
+    text = _text(installer)
+    assert "lib_sudoers.sh" in text, f"{installer.name} does not source lib_sudoers.sh"
+    args, target = CALLERS[installer]
+    call = _call(installer)
+    words = call.replace("\\\n", " ").split()
+    assert words[0] == "web_sudoers_rules"
+    assert tuple(w.strip('"') for w in words[1:8]) == args, (
+        f"{installer.name} passes the generator's arguments out of order: {call}")
+    assert words[8:] == [">", f'"{target}"'], call
+    # ...and that file is the one it runs visudo on.
+    assert f'visudo -c -f "{target}"' in text
+
+
+@pytest.mark.skipif(sys.platform == "win32" or shutil.which("bash") is None,
+                    reason="needs a POSIX bash")
+@pytest.mark.parametrize("installer", [FIRST_TIME, CONFIGURE], ids=lambda p: p.name)
+def test_installer_call_renders_the_expected_rules(installer, tmp_path):
+    """Run the installer's own call line, with a distinct value per argument."""
+    args, target = CALLERS[installer]
+    values = {
+        args[0]: "webuser", args[1]: "/srv/led root", args[2]: "/x/systemctl",
+        args[3]: "/x/bash", args[4]: "/x/reboot", args[5]: "/x/poweroff",
+        args[6]: "/x/journalctl", target: str(tmp_path / "out"),
+    }
+    assigns = "\n".join(f"{name[1:]}='{value}'" for name, value in values.items())
+    script = f"set -euo pipefail\n. '{LIB}'\n{assigns}\n{_call(installer)}\n"
+    subprocess.run(["bash", "-c", script], check=True)
+    rendered = set()
+    for line in (tmp_path / "out").read_text(encoding="utf-8").splitlines():
+        m = RULE.match(line)
+        if m:
+            assert m.group(1) == "webuser", line
+            rendered.add((m.group(2), m.group(3)))
+    subst = {"$SYSTEMCTL_PATH": "/x/systemctl", "$BASH_PATH": "/x/bash",
+             "$REBOOT_PATH": "/x/reboot", "$POWEROFF_PATH": "/x/poweroff",
+             "$JOURNALCTL_PATH": "/x/journalctl", "$PROJECT_ROOT": "/srv/led root"}
+    expected = set()
+    for tags, command in EXPECTED_GRANTS:
+        for var, value in subst.items():
+            command = command.replace(var, value)
+        expected.add((tags, command))
+    assert rendered == expected
+
+
+@pytest.mark.skipif(sys.platform == "win32" or shutil.which("bash") is None,
+                    reason="needs a POSIX bash")
+def test_optional_tools_are_left_out_when_absent(tmp_path):
+    """configure_web_sudo.sh passes "" for a missing reboot/poweroff/journalctl.
+
+    An empty path would otherwise leave `user ALL=(ALL) NOPASSWD: ` behind,
+    which visudo rejects, and the whole file would not be installed.
+    """
+    out = subprocess.run(
+        ["bash", "-c", f". '{LIB}'; web_sudoers_rules u /p /bin/systemctl /bin/bash '' '' ''"],
+        check=True, capture_output=True, text=True).stdout
+    rules = [line for line in out.splitlines() if RULE.match(line)]
+    assert len(rules) == len(EXPECTED_GRANTS) - 5
+    assert not [r for r in rules if r.rstrip().endswith("NOPASSWD:")]
+    assert "journalctl" not in out
+
+
+def test_pip_install_helper_is_granted():
+    wanted = ("NOPASSWD:", "$BASH_PATH $PROJECT_ROOT/scripts/fix_perms/safe_pip_install.sh *")
+    assert wanted in _generator_grants()
+
+
+def _granted_helpers():
+    helpers = set()
+    for _, command in _generator_grants():
+        m = re.search(r"scripts/fix_perms/([\w.-]+\.sh)", command)
+        if m:
+            helpers.add(m.group(1))
+    assert helpers, "no fix_perms helper grant found; the parser matched nothing"
+    return helpers
 
 
 def _variables(text):
@@ -60,57 +196,9 @@ def _normalise(command, variables):
     for _ in range(3):  # helper paths reference $PROJECT_ROOT
         command = re.sub(r"\$\{?([A-Z][A-Z0-9_]*)\}?",
                          lambda m: variables.get(m.group(1), m.group(0)), command)
-    command = command.replace("$PROJECT_ROOT_DIR", "$PROJECT_ROOT")
     return " ".join(command.split())
 
 
-def _grants(path):
-    """{(tags, command)} for every ledmatrix_web rule the script writes."""
-    section = _web_sudoers_section(path)
-    variables = _variables(_text(path))
-    grants = set()
-    for line in section.splitlines():
-        m = re.search(r'\$(?:WEB_USER|ACTUAL_USER) ALL=\(ALL\) (NOPASSWD:(?:NOEXEC:)?)\s*(.*)$',
-                      line)
-        if not m:
-            continue
-        command = m.group(2).rstrip().rstrip('"').rstrip()
-        grants.add((m.group(1), _normalise(command, variables)))
-    return grants
-
-
-def test_both_installers_generate_rules():
-    # Guards against the parser silently matching nothing in either file.
-    assert len(_grants(FIRST_TIME)) >= 15
-    assert len(_grants(CONFIGURE)) >= 15
-
-
-def test_installers_grant_the_same_commands():
-    first = _grants(FIRST_TIME)
-    configure = _grants(CONFIGURE)
-    only_first = {c for c in first - configure if c[1] not in ONLY_IN_FIRST_TIME}
-    only_configure = {c for c in configure - first if c[1] not in ONLY_IN_CONFIGURE}
-    assert not only_first and not only_configure, (
-        "ledmatrix_web sudoers drift between installers:\n"
-        f"  only in first_time_install.sh: {sorted(only_first)}\n"
-        f"  only in configure_web_sudo.sh: {sorted(only_configure)}")
-
-
-def test_pip_install_helper_is_granted():
-    wanted = ("NOPASSWD:", "$BASH_PATH $PROJECT_ROOT/scripts/fix_perms/safe_pip_install.sh *")
-    assert wanted in _grants(FIRST_TIME)
-    assert wanted in _grants(CONFIGURE)
-
-
-def _granted_helpers():
-    helpers = set()
-    for _, command in _grants(FIRST_TIME) | _grants(CONFIGURE):
-        m = re.search(r"scripts/fix_perms/([\w.-]+\.sh)", command)
-        if m:
-            helpers.add(m.group(1))
-    return helpers
-
-
 def test_every_granted_helper_is_hardened_in_configure_web_sudo():
     text = _text(CONFIGURE)
     variables = _variables(text)
@@ -138,9 +226,8 @@ def test_no_grant_runs_a_file_the_web_user_can_edit():
     rule for it lets the web user rewrite the file and run it as root. The
     grants for display_controller.py, start_display.sh and stop_display.sh
     were exactly that, and nothing ever ran them through sudo."""
-    for installer in (FIRST_TIME, CONFIGURE):
-        for _, command in _grants(installer):
+    for _, command in _generator_grants():
         for token in command.split():
             if token.startswith("$PROJECT_ROOT/"):
                 assert token.startswith("$PROJECT_ROOT/scripts/fix_perms/"), (
-                        f"{installer.name} grants root on a user-owned file: {command}")
+                    f"lib_sudoers.sh grants root on a user-owned file: {command}")

test/web_interface/test_systemctl_sudoers_alignment.py

@@ -1,5 +1,6 @@
 """Guards that every privileged systemctl call the web interface makes is
-covered by a passwordless-sudo grant in configure_web_sudo.sh.
+covered by a passwordless-sudo grant in scripts/install/lib_sudoers.sh, which
+both first_time_install.sh and configure_web_sudo.sh write the rules from.
 
 The web interface runs headless (no TTY), so any `sudo` call that is not
 matched by a NOPASSWD rule in /etc/sudoers.d/ledmatrix_web falls back to a
@@ -25,7 +26,7 @@ API_V3_PKG = PROJECT_ROOT / "web_interface" / "blueprints" / "api_v3"
 
 def _api_v3_source() -> str:
     return "\n".join(p.read_text() for p in sorted(API_V3_PKG.glob("*.py")))
-SUDOERS_SCRIPT = PROJECT_ROOT / "scripts" / "install" / "configure_web_sudo.sh"
+SUDOERS_SCRIPT = PROJECT_ROOT / "scripts" / "install" / "lib_sudoers.sh"
 
 
 def _sudo_systemctl_calls(source: str) -> set[tuple[str, str]]:
@@ -64,7 +65,7 @@ def test_every_sudo_systemctl_call_is_granted() -> None:
     uncovered = {c for c in calls if c not in rules}
     assert not uncovered, (
         "These sudo systemctl calls have no matching NOPASSWD grant in "
-        "configure_web_sudo.sh; they will fail headless with "
+        "lib_sudoers.sh; they will fail headless with "
         "'sudo: a terminal is required to read the password': "
         + ", ".join(f"systemctl {v} {u}" for v, u in sorted(uncovered))
     )