Phase 1/2 complete: system tray (XEMBED) + Plymouth boot splash

System tray in skydeskbar (Phase 1 #4):
- Claims _NET_SYSTEM_TRAY_S<screen> selection on startup and
  broadcasts MANAGER so nm-applet and other tray clients connect
- Handles _NET_SYSTEM_TRAY_OPCODE dock requests: XReparentWindow
  icon into the deskbar, sends XEMBED_EMBEDDED_NOTIFY
- Tray section is zero-height when empty; expands to DB_TRAY_H=26px
  when first icon embeds, shrinking back when last icon exits
- DestroyNotify / ReparentNotify clean up the icon list and
  reposition remaining icons; SelectionClear hands off gracefully
- Icon positions are updated (db_tray_reposition) whenever the app
  list changes and shifts the tray section vertically

Plymouth boot splash (Phase 2 #10):
- 'skyos' script-module theme: dark navy (#111520) background,
  "SkyOS" logo in accent blue (#90BBEE), thin progress bar
- 1×1 pixel bar_bg.png / bar_fg.png scaled at runtime by the
  Plymouth script — no large PNGs committed to the repo
- logo.png generated at build time by ImageMagick (same tool used
  for the wallpaper); build continues if ImageMagick is absent
- mkinitcpio HOOKS: added 'plymouth' after 'udev'
- Kernel cmdline: added 'splash' for UEFI systemd-boot entry
- customize_airootfs.sh: plymouth-set-default-theme skyos

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

deskbar/include/deskbar.h

@@ -25,7 +25,9 @@
  *  ├──────────────────────────┤
  *  │  [1]  [2]  [3]  [4]     │  <- workspace strip
  *  ├──────────────────────────┤
- *  │ CPU 12%    MEM 45%       │  <- status bar
+ *  │ [⊙][📶][🔋]             │  <- system tray (XEMBED; hidden when empty)
+ *  ├──────────────────────────┤
+ *  │ VOL 50%  CPU 12%  MEM 45%│  <- status bar
  *  └──────────────────────────┘
  */
 
@@ -37,6 +39,9 @@
 #define DB_ICON_SZ     18      /* app icon square size */
 #define DB_WS_H        28      /* workspace strip height */
 #define DB_STATUS_H    22      /* status bar height */
+#define DB_TRAY_H      26     /* tray section height when icons are present */
+#define DB_TRAY_ICON_SZ 20    /* embedded icon window size */
+#define DB_TRAY_MAX    16     /* maximum simultaneous tray icons */
 #define DB_MAX_APPS    32
 
 /* ── fly-out menu ────────────────────────────────────────────────────── */
@@ -133,6 +138,14 @@ typedef struct Deskbar {
     int       sub_active;   /* which sub-menu is open: 0=Apps, 1=Settings, -1=none */
     int       sub_hov;      /* hovered item in sub-menu */
     int       sw_cache;     /* cached screen width for menu positioning */
+
+    /* system tray (freedesktop.org XEmbed tray protocol) */
+    Window    tray_icons[DB_TRAY_MAX];
+    int       n_tray_icons;
+    Atom      atom_tray_s0;     /* _NET_SYSTEM_TRAY_S<screen> */
+    Atom      atom_tray_opcode; /* _NET_SYSTEM_TRAY_OPCODE */
+    Atom      atom_xembed;      /* _XEMBED */
+    Atom      atom_manager;     /* MANAGER */
 } Deskbar;
 
 void db_init(Deskbar *db);

deskbar/src/deskbar.c

@@ -1,5 +1,9 @@
 #include "deskbar.h"
 
+#define TRAY_REQUEST_DOCK      0
+#define XEMBED_EMBEDDED_NOTIFY 0
+#define XEMBED_VERSION         0
+
 /* ── layout ───────────────────────────────────────────────────────────── */
 
 int db_apps_y(void) { return DB_TOP_H + 1; }
@@ -8,8 +12,11 @@ int db_ws_y(Deskbar *db) {
     return db_apps_y() + db->napps * DB_ITEM_H + 1;
 }
 
+static int db_tray_h(Deskbar *db)  { return db->n_tray_icons > 0 ? DB_TRAY_H : 0; }
+static int db_tray_y(Deskbar *db)  { return db_ws_y(db) + DB_WS_H + 1; }
 static int db_status_y(Deskbar *db) {
-    return db_ws_y(db) + DB_WS_H + 1;
+    int th = db_tray_h(db);
+    return db_tray_y(db) + th + (th > 0 ? 1 : 0);
 }
 
 void db_resize(Deskbar *db) {
@@ -141,6 +148,65 @@ void db_update_workspace(Deskbar *db) {
     db->num_ws = (nws > 0)  ? (int)nws : 4;
 }
 
+/* ── system tray (XEmbed) ─────────────────────────────────────────────── */
+
+static void db_tray_reposition(Deskbar *db) {
+    int ty = db_tray_y(db);
+    int iy = (DB_TRAY_H - DB_TRAY_ICON_SZ) / 2;
+    for (int i = 0; i < db->n_tray_icons; i++) {
+        int ix = 4 + i * (DB_TRAY_ICON_SZ + 4);
+        XMoveWindow(db->dpy, db->tray_icons[i], ix, ty + iy);
+    }
+}
+
+static void db_tray_dock(Deskbar *db, Window icon_win) {
+    if (db->n_tray_icons >= DB_TRAY_MAX) return;
+    for (int i = 0; i < db->n_tray_icons; i++)
+        if (db->tray_icons[i] == icon_win) return;
+
+    int ty        = db_tray_y(db);
+    int iy        = (DB_TRAY_H - DB_TRAY_ICON_SZ) / 2;
+    int ix        = 4 + db->n_tray_icons * (DB_TRAY_ICON_SZ + 4);
+    int was_empty = (db->n_tray_icons == 0);
+
+    XSelectInput(db->dpy, icon_win, StructureNotifyMask);
+    XReparentWindow(db->dpy, icon_win, db->win, ix, ty + iy);
+    XResizeWindow(db->dpy, icon_win, DB_TRAY_ICON_SZ, DB_TRAY_ICON_SZ);
+    XMapWindow(db->dpy, icon_win);
+
+    /* XEMBED_EMBEDDED_NOTIFY message to the icon */
+    XEvent ev = {0};
+    ev.xclient.type         = ClientMessage;
+    ev.xclient.window       = icon_win;
+    ev.xclient.message_type = db->atom_xembed;
+    ev.xclient.format       = 32;
+    ev.xclient.data.l[0]    = CurrentTime;
+    ev.xclient.data.l[1]    = XEMBED_EMBEDDED_NOTIFY;
+    ev.xclient.data.l[2]    = 0;
+    ev.xclient.data.l[3]    = db->win;
+    ev.xclient.data.l[4]    = XEMBED_VERSION;
+    XSendEvent(db->dpy, icon_win, False, NoEventMask, &ev);
+
+    db->tray_icons[db->n_tray_icons++] = icon_win;
+    if (was_empty) db_resize(db);
+    db_draw(db);
+}
+
+static void db_tray_remove(Deskbar *db, Window icon_win) {
+    int pos = -1;
+    for (int i = 0; i < db->n_tray_icons; i++)
+        if (db->tray_icons[i] == icon_win) { pos = i; break; }
+    if (pos < 0) return;
+
+    memmove(&db->tray_icons[pos], &db->tray_icons[pos + 1],
+            (db->n_tray_icons - pos - 1) * sizeof(Window));
+    db->n_tray_icons--;
+
+    db_tray_reposition(db);
+    if (db->n_tray_icons == 0) db_resize(db);
+    db_draw(db);
+}
+
 /* ── system status ────────────────────────────────────────────────────── */
 
 static int read_cpu_percent(void) {
@@ -429,6 +495,17 @@ void db_draw(Deskbar *db) {
     XDrawLine(db->dpy, db->win, db->gc,
               0, wy + DB_WS_H, DB_W, wy + DB_WS_H);
 
+    /* ── SYSTEM TRAY ── */
+    if (db->n_tray_icons > 0) {
+        int ty = db_tray_y(db);
+        XSetForeground(db->dpy, db->gc, db_color(db, DB_COL_BG));
+        XFillRectangle(db->dpy, db->win, db->gc, 0, ty, DB_W, DB_TRAY_H);
+
+        /* separator below tray */
+        XSetForeground(db->dpy, db->gc, db_color(db, DB_COL_BORDER_D));
+        XDrawLine(db->dpy, db->win, db->gc, 0, ty + DB_TRAY_H, DB_W, ty + DB_TRAY_H);
+    }
+
     /* ── STATUS BAR ── */
     int sy = db_status_y(db);
     XSetForeground(db->dpy, db->gc, db_color(db, DB_COL_BG));
@@ -807,6 +884,7 @@ void db_init(Deskbar *db) {
     db->sub_active   = -1;
     db->sub_hov      = -1;
     db->sw_cache     = 0;
+    db->n_tray_icons = 0;
 
     db->net_client_list        = XInternAtom(db->dpy, "_NET_CLIENT_LIST",        False);
     db->net_active_window      = XInternAtom(db->dpy, "_NET_ACTIVE_WINDOW",      False);
@@ -815,6 +893,15 @@ void db_init(Deskbar *db) {
     db->net_wm_name            = XInternAtom(db->dpy, "_NET_WM_NAME",            False);
     db->utf8_string            = XInternAtom(db->dpy, "UTF8_STRING",             False);
 
+    {
+        char sel_name[32];
+        snprintf(sel_name, sizeof(sel_name), "_NET_SYSTEM_TRAY_S%d", db->screen);
+        db->atom_tray_s0 = XInternAtom(db->dpy, sel_name, False);
+    }
+    db->atom_tray_opcode = XInternAtom(db->dpy, "_NET_SYSTEM_TRAY_OPCODE", False);
+    db->atom_xembed      = XInternAtom(db->dpy, "_XEMBED",                 False);
+    db->atom_manager     = XInternAtom(db->dpy, "MANAGER",                 False);
+
     db->font_ui    = XftFontOpenName(db->dpy, db->screen, DB_FONT_UI);
     db->font_menu  = XftFontOpenName(db->dpy, db->screen, DB_FONT_MENU);
     db->font_clock = XftFontOpenName(db->dpy, db->screen, DB_FONT_CLOCK);
@@ -829,7 +916,7 @@ void db_init(Deskbar *db) {
     db_update_apps(db);
     db_update_workspace(db);
 
-    db->bar_h = DB_TOP_H + 1 + db->napps * DB_ITEM_H + 1 + DB_WS_H + 1 + DB_STATUS_H + 2;
+    db->bar_h = db_status_y(db) + DB_STATUS_H + 2;
 
     int sw = DisplayWidth(db->dpy, db->screen);
 
@@ -847,6 +934,20 @@ void db_init(Deskbar *db) {
         CWOverrideRedirect | CWBackPixel | CWEventMask, &swa);
     db->gc = XCreateGC(db->dpy, db->win, 0, NULL);
 
+    /* Claim _NET_SYSTEM_TRAY_S<screen> selection and announce ourselves */
+    XSetSelectionOwner(db->dpy, db->atom_tray_s0, db->win, CurrentTime);
+    if (XGetSelectionOwner(db->dpy, db->atom_tray_s0) == db->win) {
+        XEvent sev = {0};
+        sev.xclient.type         = ClientMessage;
+        sev.xclient.window       = db->root;
+        sev.xclient.message_type = db->atom_manager;
+        sev.xclient.format       = 32;
+        sev.xclient.data.l[0]    = CurrentTime;
+        sev.xclient.data.l[1]    = db->atom_tray_s0;
+        sev.xclient.data.l[2]    = db->win;
+        XSendEvent(db->dpy, db->root, False, StructureNotifyMask, &sev);
+    }
+
     Atom net_wm_window_type = XInternAtom(db->dpy, "_NET_WM_WINDOW_TYPE", False);
     Atom net_wm_type_dock   = XInternAtom(db->dpy, "_NET_WM_WINDOW_TYPE_DOCK", False);
     XChangeProperty(db->dpy, db->win, net_wm_window_type, XA_ATOM, 32,
@@ -943,10 +1044,30 @@ void db_run(Deskbar *db) {
                     e.xvisibility.state != VisibilityUnobscured)
                     XRaiseWindow(db->dpy, db->win);
                 break;
+            case ClientMessage:
+                if (e.xclient.message_type == db->atom_tray_opcode &&
+                    e.xclient.data.l[1] == TRAY_REQUEST_DOCK)
+                    db_tray_dock(db, (Window)e.xclient.data.l[2]);
+                break;
+            case DestroyNotify:
+                db_tray_remove(db, e.xdestroywindow.window);
+                break;
+            case ReparentNotify:
+                if (e.xreparent.parent != db->win)
+                    db_tray_remove(db, e.xreparent.window);
+                break;
+            case SelectionClear:
+                if (e.xselectionclear.selection == db->atom_tray_s0) {
+                    db->n_tray_icons = 0;
+                    db_resize(db);
+                    db_draw(db);
+                }
+                break;
             case PropertyNotify:
                 if (e.xproperty.atom == db->net_client_list) {
                     /* Window list changed — full refresh + resize */
                     db_update_apps(db);
+                    db_tray_reposition(db);
                     db_resize(db);
                     db_draw(db);
                 } else if (e.xproperty.atom == db->net_active_window) {

iso/docker/entrypoint.sh

@@ -101,6 +101,7 @@ git
 sudo
 bash-completion
 fastfetch
+plymouth
 PKGS
 
 # ── 3. airootfs overlay — files that land in the live system ─────────
@@ -188,7 +189,7 @@ cat > "$AIROOTFS/etc/mkinitcpio.conf.d/archiso.conf" <<'MKCONF'
 MODULES=()
 BINARIES=()
 FILES=()
-HOOKS=(base udev microcode archiso block filesystems keyboard)
+HOOKS=(base udev plymouth microcode archiso block filesystems keyboard)
 MKCONF
 echo ">>> Live initramfs HOOKS: base udev microcode archiso block filesystems keyboard"
 
@@ -531,6 +532,83 @@ gtk-icon-theme-name=Adwaita
 gtk-cursor-theme-name=DMZ-White
 GTK3
 
+# ── Plymouth dark navy boot splash ───────────────────────────────────
+echo ">>> Creating Plymouth theme..."
+PLYM="$AIROOTFS/usr/share/plymouth/themes/skyos"
+mkdir -p "$PLYM"
+
+cat > "$PLYM/skyos.plymouth" <<'PLYMDEF'
+[Plymouth Theme]
+Name=SkyOS
+Description=SkyOS dark navy boot splash
+ModuleName=script
+
+[script]
+ImageDir=/usr/share/plymouth/themes/skyos
+ScriptFile=/usr/share/plymouth/themes/skyos/skyos.script
+PLYMDEF
+
+cat > "$PLYM/skyos.script" <<'PLYMSCRIPT'
+# SkyOS Plymouth boot splash — dark navy + accent blue progress bar
+
+W = Window.GetWidth();
+H = Window.GetHeight();
+
+# Solid dark navy background
+Window.SetBackgroundTopColor(0.067, 0.082, 0.125);
+Window.SetBackgroundBottomColor(0.040, 0.055, 0.090);
+
+# Logo (centered, upper third of screen)
+logo = Image("logo.png");
+logo_sprite = Sprite(logo);
+logo_sprite.SetPosition(
+    Math.Int((W - logo.GetWidth())  / 2),
+    Math.Int(H * 0.40 - logo.GetHeight() / 2),
+    1
+);
+
+# Progress bar
+BAR_W = Math.Int(Math.Min(W * 0.42, 440));
+BAR_H = 4;
+bar_x = Math.Int((W - BAR_W) / 2);
+bar_y = Math.Int(H * 0.72);
+
+# Bar background track (dark blue-grey)
+bar_bg = Image("bar_bg.png").Scale(BAR_W, BAR_H);
+bar_bg_sprite = Sprite(bar_bg);
+bar_bg_sprite.SetPosition(bar_x, bar_y, 2);
+
+# Bar fill (accent blue, grows with progress)
+bar_fill_sprite = Sprite();
+bar_fill_sprite.SetPosition(bar_x, bar_y, 3);
+
+fun boot_progress_callback(time, progress) {
+    fill_w = Math.Int(BAR_W * progress);
+    if (fill_w < 2) fill_w = 2;
+    bar_fill = Image("bar_fg.png").Scale(fill_w, BAR_H);
+    bar_fill_sprite.SetImage(bar_fill);
+}
+
+Plymouth.SetBootProgressFunction(boot_progress_callback);
+PLYMSCRIPT
+
+# Generate PNG assets (ImageMagick is used above for the wallpaper)
+if command -v convert &>/dev/null; then
+    # Logo: "SkyOS" in accent blue on transparent background
+    convert -size 340x90 xc:none \
+        -font DejaVu-Sans-Bold -pointsize 62 \
+        -fill "#90BBEE" -gravity center \
+        -annotate 0 "SkyOS" \
+        "$PLYM/logo.png" 2>/dev/null \
+        && echo "    Plymouth logo generated." \
+        || echo "    Plymouth logo generation failed (non-fatal)."
+    # 1×1 pixel images — scaled at runtime by the script
+    convert -size 1x1 xc:"#1C2840" "$PLYM/bar_bg.png" 2>/dev/null || true
+    convert -size 1x1 xc:"#1E58A8" "$PLYM/bar_fg.png" 2>/dev/null || true
+else
+    echo "    ImageMagick not available — Plymouth PNGs skipped."
+fi
+
 # ── Mac hardware: libinput touchpad config ────────────────────────────
 mkdir -p "$AIROOTFS/etc/X11/xorg.conf.d"
 cat > "$AIROOTFS/etc/X11/xorg.conf.d/40-libinput.conf" <<'TOUCHPAD'
@@ -626,7 +704,7 @@ cat > "$PROFILE/efiboot/loader/entries/skyos.conf" <<'ENTRY'
 title   SkyOS
 linux   /arch/boot/x86_64/vmlinuz-linux
 initrd  /arch/boot/x86_64/initramfs-linux.img
-options archisobasedir=arch archisolabel=%ARCHISO_LABEL% quiet loglevel=3
+options archisobasedir=arch archisolabel=%ARCHISO_LABEL% quiet splash loglevel=3
 ENTRY
 
 
@@ -694,6 +772,9 @@ update-desktop-database 2>/dev/null || true
 # Fontconfig cache
 fc-cache -f 2>/dev/null || true
 
+# Plymouth: set SkyOS as the default theme (archiso runs mkinitcpio after this)
+plymouth-set-default-theme skyos 2>/dev/null || true
+
 # xscreensaver config (screen lock)
 mkdir -p /etc/skel
 cat > /etc/skel/.xscreensaver <<'SS'