Fix clock layout shift with tabular digits and fixed width

modules/home/ags/app/style.scss

@@ -77,6 +77,7 @@ $module-bg: transparentize($base02, 0.4);
 
 .clock {
     font-weight: bold;
+    font-feature-settings: "tnum";
 }
 
 .clock icon {

modules/home/ags/app/widget/Clock.tsx

@@ -1,4 +1,6 @@
 import GLib from "gi://GLib"
+import Pango from "gi://Pango"
+import Gtk from "gi://Gtk?version=3.0"
 import { Variable, bind } from "astal"
 
 const time = Variable("").poll(1000, () => {
@@ -7,11 +9,43 @@ const time = Variable("").poll(1000, () => {
     return `${now.format("%a, %d %b")}, ${clock}`
 })
 
+// widest possible tick: days 1-7 always cover every weekday, sampled across
+// all months with a double-digit hour in both meridiems; measured once at
+// realize with the label's own font (tnum forced on) so the fixed
+// widthRequest stops the bar from shifting every minute
+function widestTick(self: Gtk.Label): number {
+    const layout = self.create_pango_layout("")
+    const attrs = new Pango.AttrList()
+    attrs.insert(Pango.attr_font_features_new("tnum"))
+    layout.set_attributes(attrs)
+
+    let widest = 0
+    for (let month = 1; month <= 12; month++) {
+        for (let day = 1; day <= 7; day++) {
+            for (const hour of [10, 22]) {
+                const d = GLib.DateTime.new_local(2026, month, day, hour, 0, 0)
+                const tick =
+                    `${d.format("%a, %d %b")}, ${d.format("%I:%M %p")!.replace(/^0/, "")}`
+                layout.set_text(tick, -1)
+                const [w] = layout.get_pixel_size()
+                widest = Math.max(widest, w)
+            }
+        }
+    }
+    return Math.ceil(widest) + 2
+}
+
 export default function Clock() {
     return (
         <box spacing={6}>
             <icon icon="clock-hands-symbolic" />
-            <label className="clock" label={bind(time)} />
+            <label
+                className="clock"
+                label={bind(time)}
+                onRealize={(self) => {
+                    self.width_request = widestTick(self as Gtk.Label)
+                }}
+            />
         </box>
     )
 }