Fix auto-stop issue and add polkit rule (pkgrel=2)

- Add systemd drop-in override to fix StopWhenUnneeded auto-stop issue
- Add polkit rule for passwordless fcp-server management by audio group
- Improve post_install messages with troubleshooting guidance
- Add polkit to optdepends

This fixes the reliability issue where fcp-server would stop immediately
after being started by udev, preventing alsa-scarlett-gui from connecting.

Changes follow best practices:
- Drop-in override (non-invasive, survives upstream updates)
- Polkit rule follows PulseAudio/PipeWire precedent for audio group
- Comprehensive security review completed (see SECURITY_REVIEW.md)

.SRCINFO

@@ -1,7 +1,7 @@
 pkgbase = fcp-support-git
 	pkgdesc = Focusrite Control Protocol user-space driver for Scarlett 4th Gen big models (16i16, 18i16, 18i20)
 	pkgver = r21.edae476
-	pkgrel = 1
+	pkgrel = 2
 	url = https://github.com/geoffreybennett/fcp-support
 	install = fcp-support-git.install
 	arch = x86_64
@@ -19,6 +19,7 @@ pkgbase = fcp-support-git
 	depends = libcap
 	optdepends = alsa-scarlett-gui-git: GUI for controlling Focusrite interfaces
 	optdepends = scarlett4-firmware: Firmware files for Scarlett 4th Gen (required for first-time setup)
+	optdepends = polkit: Passwordless start/stop of fcp-server for audio group users (recommended)
 	provides = fcp-support
 	conflicts = fcp-support
 	source = git+https://github.com/geoffreybennett/fcp-support.git

PKGBUILD

@@ -3,7 +3,7 @@
 pkgname=fcp-support-git
 _pkgname=fcp-support
 pkgver=r21.edae476
-pkgrel=1
+pkgrel=2
 pkgdesc="Focusrite Control Protocol user-space driver for Scarlett 4th Gen big models (16i16, 18i16, 18i20)"
 arch=('x86_64' 'i686')
 url="https://github.com/geoffreybennett/fcp-support"
@@ -25,6 +25,7 @@ makedepends=(
 optdepends=(
     'alsa-scarlett-gui-git: GUI for controlling Focusrite interfaces'
     'scarlett4-firmware: Firmware files for Scarlett 4th Gen (required for first-time setup)'
+    'polkit: Passwordless start/stop of fcp-server for audio group users (recommended)'
 )
 provides=("$_pkgname")
 conflicts=("$_pkgname")
@@ -54,4 +55,40 @@ package() {
     make install \
         PREFIX=/usr \
         DESTDIR="$pkgdir"
+
+    # Install systemd drop-in to fix StopWhenUnneeded issue
+    # The upstream service has StopWhenUnneeded=yes which causes systemd to stop
+    # the service immediately after udev starts it, breaking reliability
+    install -Dm644 /dev/stdin \
+        "$pkgdir/usr/lib/systemd/system/fcp-server@.service.d/arch.conf" <<'EOF'
+# Arch Linux package override for fcp-server auto-stop issue
+# See: https://github.com/geoffreybennett/fcp-support/issues
+#
+# The upstream service has StopWhenUnneeded=yes which conflicts with udev-based
+# activation. This override keeps the service running while the device is connected.
+
+[Unit]
+# Keep service running while device is connected
+StopWhenUnneeded=no
+
+[Service]
+# Always restart on crash
+Restart=always
+RestartSec=3
+EOF
+
+    # Install polkit rule to allow audio group to manage fcp-server without password
+    # This enables alsa-scarlett-gui to auto-start the server seamlessly
+    install -Dm644 /dev/stdin \
+        "$pkgdir/usr/share/polkit-1/rules.d/50-fcp-server.rules" <<'EOF'
+// Allow audio group members to start/stop fcp-server without authentication
+// This enables seamless integration with alsa-scarlett-gui
+polkit.addRule(function(action, subject) {
+    if (action.id == "org.freedesktop.systemd1.manage-units" &&
+        action.lookup("unit").match(/^fcp-server@[0-9]+\.service$/) &&
+        subject.isInGroup("audio")) {
+        return polkit.Result.YES;
+    }
+});
+EOF
 }

fcp-support-git.install

@@ -26,6 +26,11 @@ post_install() {
     echo "    sudo usermod -a -G audio \$USER"
     echo "    (then log out and back in)"
     echo ""
+    echo "==> Package improvements in this version:"
+    echo "    - Fixed auto-stop issue (service now stays running reliably)"
+    echo "    - Added polkit rule (audio group can manage fcp-server without password)"
+    echo "    - Better integration with alsa-scarlett-gui"
+    echo ""
     echo "==> Install 'alsa-scarlett-gui-git' for a graphical interface:"
     echo "    yay -S alsa-scarlett-gui-git"
     echo ""
@@ -33,6 +38,12 @@ post_install() {
     echo "    Install scarlett4-firmware package and run:"
     echo "    fcp-tool --update-firmware"
     echo ""
+    echo "==> Troubleshooting:"
+    echo "    If service doesn't auto-start, manually start it:"
+    echo "      systemctl start fcp-server@<card-number>"
+    echo "      (find card number with: aplay -l)"
+    echo "    View logs: journalctl -u 'fcp-server@*' -f"
+    echo ""
 }
 
 post_upgrade() {