diff --git a/ui/shared/power/screen.js b/ui/shared/power/screen.js
index 9c75b52..1ef1a82 100644
--- a/ui/shared/power/screen.js
+++ b/ui/shared/power/screen.js
@@ -1,6 +1,13 @@
 // SPDX-License-Identifier: AGPL-3.0-or-later
 
 // Screen power (on/off), on top of `navigator.embedder.power`.
+//
+// Darkening the panel also raises the input shield, and lighting it lowers it.
+
+import {
+  lowerShield,
+  raiseShield,
+} from "beaver://shared/power/screen_shield.js";
 
 // The DOM power object, or null on a page/build that can't reach it.
 function powerApi() {
@@ -44,10 +51,13 @@ class ScreenPower {
   }
 
   off() {
+    // Shield first, before the panel goes dark.
+    raiseShield({ onWake: () => this.wake() });
     this.set(false);
   }
 
   wake() {
+    lowerShield();
     this.set(true);
   }
 }
diff --git a/ui/shared/power/screen_shield.js b/ui/shared/power/screen_shield.js
new file mode 100644
index 0000000..0bcde61
--- /dev/null
+++ b/ui/shared/power/screen_shield.js
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+// The shield: what covers the screen while the panel is dark.
+//
+// This manages the wake gesture: a double tap wake.
+
+// Above the dusk veil (9000), which is itself above --z-modal: the fade may
+// still be running when the panel is cut.
+const SHIELD_Z_INDEX = 9500;
+
+// Two taps inside this window, and this far apart at most, count as a double
+// tap.
+const DOUBLE_TAP_MS = 500;
+const DOUBLE_TAP_SLOP_PX = 80;
+
+let shield = null;
+let lastTap = null;
+let wakeAction = null;
+
+/**
+ * Cover the screen. Idempotent; the first caller's `onWake` stands.
+ *
+ * @param {object} [options]
+ * @param {Function} [options.onWake] Run when the user double taps.
+ */
+export function raiseShield({ onWake } = {}) {
+  if (shield) {
+    return;
+  }
+  lastTap = null;
+  wakeAction = onWake ?? null;
+
+  shield = document.createElement("div");
+  shield.className = "screen-shield";
+  shield.style.cssText = [
+    "position: fixed",
+    "inset: 0",
+    `z-index: ${SHIELD_Z_INDEX}`,
+    // Transparent: the dusk veil and the screen-off effect do the visuals.
+    // This element exists only to catch input.
+    "background: transparent",
+    // Servo ignores touch-action, so the handlers below are what actually stop
+    // the gesture. Declared anyway for correctness elsewhere.
+    "touch-action: none",
+  ].join(";");
+
+  // Capture phase, and every pointer/touch stage: a swallowed `down` whose
+  // `move` and `up` still landed would leave the page mid-gesture.
+  for (const type of [
+    "pointerdown",
+    "pointermove",
+    "pointerup",
+    "pointercancel",
+    "touchstart",
+    "touchmove",
+    "touchend",
+    "touchcancel",
+    "click",
+    "dblclick",
+    "contextmenu",
+    "wheel",
+  ]) {
+    shield.addEventListener(type, swallow, true);
+  }
+  shield.addEventListener("pointerup", onTap, true);
+
+  document.body.appendChild(shield);
+}
+
+// Uncover the screen. Idempotent.
+export function lowerShield() {
+  shield?.remove();
+  shield = null;
+  lastTap = null;
+  wakeAction = null;
+}
+
+// True while the shield is up, i.e. while the screen is meant to be dark.
+export function shieldIsUp() {
+  return shield !== null;
+}
+
+function swallow(event) {
+  event.preventDefault();
+  event.stopPropagation();
+}
+
+// A double tap wakes. Tracked on pointerup rather than pointerdown so a press
+// that turns into a drag does not count as a tap.
+function onTap(event) {
+  const now = event.timeStamp;
+  const previous = lastTap;
+  lastTap = { x: event.clientX, y: event.clientY, at: now };
+
+  if (
+    previous &&
+    now - previous.at <= DOUBLE_TAP_MS &&
+    Math.abs(event.clientX - previous.x) <= DOUBLE_TAP_SLOP_PX &&
+    Math.abs(event.clientY - previous.y) <= DOUBLE_TAP_SLOP_PX
+  ) {
+    const wake = wakeAction;
+    lowerShield();
+    wake?.();
+  }
+}