feat(installer): Skip login manager when unl0kr handles the passphrase

unl0kr already prompts for the LUKS passphrase on screen, so a login
manager on top of it would be a second prompt. The login screen now only
collects a fallback (none/greetd/sddm/gdm) when unl0kr is selected;
resolve_login_manager applies it only when install_unl0kr falls back to
the systemd initramfs, and the summary shows both states.

Also ships /etc/unl0kr.conf (breezy-dark) plus the empty
/usr/share/unl0kr/unl0kr.conf the package omits so unl0kr stops warning
about an unparseable config, and pins Hyprland in the user's
AccountsService record so gdm autologin does not fall back to
gnome.desktop.

AGENTS.md

@@ -74,7 +74,7 @@ The airootfs overlay ships it as `/usr/local/bin/alvin-install` (mode `0755` for
   locale, login manager, sshd, summary) then a fixed order of `install_*` steps
   (partition → LUKS → format/mount → pacstrap → fstab → repos → timezone → locale →
   hostname → network → sshd → user → git/SSH → end-4 dots → mkinitcpio → bootloader →
-  TPM/unl0kr → login manager → autologin → update (reflector + keyrings + `pacman -Syu`, warn-only) → cleanup). Screens and install steps are
+  TPM/unl0kr → login manager (none if unl0kr succeeded; with unl0kr selected the login screen only asks for a fallback) → autologin → update (reflector + keyrings + `pacman -Syu`, warn-only) → cleanup). Screens and install steps are
   independent — edit one without
   touching the other. An `EXIT` trap unmounts `$TARGET` and closes `cryptroot` on any exit.
 - **Package list**: `install_pacstrap` builds the *installed* system's list from the medium's

airootfs/usr/local/bin/alvin-install

@@ -31,6 +31,9 @@ GH_USERNAME=""
 UNL0KR="false"
 TPM_STATUS=""
 LOGIN_MANAGER="none"
+# true when unl0kr was picked: no login manager is installed if unl0kr
+# succeeds, and LOGIN_MANAGER only holds the fallback for when it doesn't.
+LOGIN_MANAGER_SKIP="false"
 AUTOLOGIN=""
 # SSHD is the choice made on the sshd screen; SSHD_APPLIED is only flipped once
 # the target's sshd.service has actually been enabled, so the final banner can
@@ -527,6 +530,11 @@ screen_locale() {
 }
 
 screen_login_manager() {
+  if [[ "$LUKS" == "true" && "$UNL0KR" == "true" ]]; then
+    screen_unl0kr_login
+    return
+  fi
+  LOGIN_MANAGER_SKIP="false"
   clear
   header "Login Manager"
   echo ""
@@ -543,6 +551,33 @@ screen_login_manager() {
   log "Login manager: $LOGIN_MANAGER"
 }
 
+# unl0kr already asks for the passphrase on screen at boot, so a login
+# manager on top would be a second prompt. Skip it, but collect a fallback
+# now: install_unl0kr can still fall back to the systemd initramfs, and the
+# installer must not stop to ask mid-install.
+screen_unl0kr_login() {
+  LOGIN_MANAGER_SKIP="true"
+  clear
+  header "Login Manager (unl0kr)"
+  echo ""
+  gum style --foreground 15 \
+    "unl0kr is selected, so no login manager will be installed:" \
+    "after the LUKS passphrase is entered with unl0kr, the system logs in on" \
+    "tty1 and Hyprland starts automatically (autologin is asked during install)." \
+    "" \
+    "If unl0kr fails to install, the installer falls back to the standard" \
+    "passphrase prompt. Pick the login manager to use in that case:" \
+    "" \
+    "  none    - plain tty login, Hyprland starts automatically" \
+    "  greetd  - lightweight TUI greeter (tuigreet)" \
+    "  sddm    - Qt display manager (already installed)" \
+    "  gdm     - GNOME display manager (large download)"
+  echo ""
+  LOGIN_MANAGER=$(gum choose --header "+ Fallback login manager (Enter = none)" \
+    "none" "greetd" "sddm" "gdm") || die "No fallback login manager selected."
+  log "Login manager: skipped for unl0kr (fallback: $LOGIN_MANAGER)"
+}
+
 screen_sshd() {
   clear
   header "SSH Server"
@@ -592,6 +627,11 @@ screen_summary() {
     ssh_line="gh:${GH_USERNAME}"
   fi
 
+  local login_line="${LOGIN_MANAGER}"
+  if [[ "$LOGIN_MANAGER_SKIP" == "true" ]]; then
+    login_line="none - unl0kr (fallback: ${LOGIN_MANAGER})"
+  fi
+
   gum style --foreground 15 --border normal --border-foreground 8 \
     --padding "0 2" --width 60 \
     "Disk:        ${DISK}" \
@@ -603,7 +643,7 @@ screen_summary() {
     "Keymap:      ${KEYMAP}" \
     "Locale:      ${LOCALE}" \
     "Timezone:    ${TIMEZONE}" \
-    "Login mgr:   ${LOGIN_MANAGER}" \
+    "Login mgr:   ${login_line}" \
     "SSH server:  $([[ "$SSHD" == "true" ]] && echo enabled || echo skipped)" \
     "SSH keys:    ${ssh_line}" \
     "Git:         ${git_line}"
@@ -1715,6 +1755,34 @@ install_unl0kr() {
     page_log_tail "unl0kr hook file output (q to quit)" 40 || true
   }
 
+  # unl0kr parses /usr/share/unl0kr/unl0kr.conf first; the package doesn't
+  # ship it, so inih fails to open it and unl0kr prints "Ignoring invalid
+  # config file" on every boot. An empty file parses cleanly - FILES+= puts
+  # it in the image (the hook only adds /etc/unl0kr.conf). Our own
+  # /etc/unl0kr.conf pins the dark theme instead of trusting the PKGBUILD's
+  # sed on the upstream (light) default.
+  mkdir -p "${TARGET}/usr/share/unl0kr"
+  : >"${TARGET}/usr/share/unl0kr/unl0kr.conf"
+  cat >"${TARGET}/etc/unl0kr.conf" <<'UNL0KR'
+[general]
+animations=true
+
+[keyboard]
+autohide=false
+layout=us
+popovers=true
+
+[textarea]
+obscured=true
+
+[theme]
+default=breezy-dark
+alternate=breezy-light
+UNL0KR
+  echo 'FILES+=(/usr/share/unl0kr/unl0kr.conf)' \
+    >>"${TARGET}/etc/mkinitcpio.conf.d/alvin.conf"
+  log "unl0kr: wrote /etc/unl0kr.conf (breezy-dark) + empty /usr/share/unl0kr/unl0kr.conf"
+
   # Touchscreen/input stack for the initramfs: mkinitcpio fails the build
   # on a MODULES entry it cannot resolve, and -P applies the list to every
   # preset - so a module may enter MODULES only if EVERY installed kernel
@@ -1904,6 +1972,21 @@ FISH
   log "tty profile: ${profile} (exec Hyprland on VT1)"
 }
 
+# Runs after install_unl0kr, which resets UNL0KR to false when it falls
+# back to the systemd initramfs - so UNL0KR still being true here means
+# unl0kr really is in the image and no login manager is wanted.
+resolve_login_manager() {
+  [[ "$LOGIN_MANAGER_SKIP" == "true" ]] || return 0
+  if [[ "$UNL0KR" == "true" ]]; then
+    LOGIN_MANAGER="none"
+    info "unl0kr is installed - skipping the login manager (tty1 + Hyprland)."
+    log "Login manager: none (unl0kr installed)"
+  else
+    warn "unl0kr fell back - using the fallback login manager: ${LOGIN_MANAGER}."
+    log "Login manager: fallback ${LOGIN_MANAGER} (unl0kr not installed)"
+  fi
+}
+
 install_login_manager() {
   info "Configuring login manager: ${LOGIN_MANAGER}..."
 
@@ -2009,6 +2092,19 @@ TOML
       return
     fi
     ensure_hyprland_session
+    # gdm (autologin included) starts the session stored in the user's
+    # AccountsService record; without one it picks gnome.desktop, which
+    # the gdm install drags in. Pin Hyprland.
+    local as_dir="${TARGET}/var/lib/AccountsService/users"
+    mkdir -p "$as_dir"
+    cat >"${as_dir}/${USERNAME}" <<'ACCOUNT'
+[User]
+Session=hyprland
+SessionType=wayland
+SystemAccount=false
+ACCOUNT
+    chmod 600 "${as_dir}/${USERNAME}"
+    log "gdm: AccountsService session pinned to hyprland"
     if run_logged "Could not enable gdm.service" \
       arch-chroot "$TARGET" systemctl enable gdm.service; then
       run_logged "Could not disable getty@tty1.service" \
@@ -2286,6 +2382,7 @@ main() {
   install_bootloader
   install_tpm
   install_unl0kr
+  resolve_login_manager
   install_login_manager
   install_autologin
   install_update