Let a tooltip linger, and tell the screen reader what it says

A plain tooltip vanished the instant the pointer left, where M3 keeps one for
1.5s and shows only one at a time — these are popover="manual", so nothing was
closing the last one. A rich tooltip's bubble was never associated with its
trigger at all, so the explanation it exists to give was never announced; the
script now writes aria-describedby (and aria-haspopup/aria-expanded when it is
persistent) onto the focusable control in the trigger slot, and again after a
morph. Plan step 18, actions.md ACT-22, ACT-25.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9

resources/js/tooltip.js

@@ -3,10 +3,15 @@
  *
  * The trigger is the popover's parent element (the button, or the standalone wrapper). Hover
  * counts only for a pointer that can hover, after a short delay so a pointer passing over a
- * toolbar does not flash every label; keyboard focus shows it at once. A press, leaving, blur
- * and Escape hide it.
+ * toolbar does not flash every label; keyboard focus shows it at once. A press and Escape hide it
+ * at once; leaving and blur let it stand for M3's 1.5s, so the words can still be read while the
+ * pointer moves on. Only one tooltip is up at a time: showing one takes the last one down, which
+ * the browser will not do for us because these are `popover="manual"`.
  */
 const HOVER_DELAY_MS = 500
+const LEAVE_DELAY_MS = 1500
+
+let visible = null
 
 document.addEventListener('alpine:init', () => {
     window.Alpine.data('materialTooltip', () => ({
@@ -22,25 +27,37 @@ document.addEventListener('alpine:init', () => {
             const show = (delay) => {
                 clearTimeout(this.timer)
                 this.timer = setTimeout(() => {
-                    if (tip.isConnected && !open()) {
-                        tip.showPopover()
+                    if (!tip.isConnected || open()) {
+                        return
+                    }
+
+                    if (visible && visible !== tip && visible.matches(':popover-open')) {
+                        visible.hidePopover()
+                    }
+
+                    visible = tip
+                    tip.showPopover()
+                }, delay)
+            }
+
+            const hide = (delay = 0) => {
+                clearTimeout(this.timer)
+                this.timer = setTimeout(() => {
+                    if (open()) {
+                        tip.hidePopover()
+                    }
+
+                    if (visible === tip) {
+                        visible = null
                     }
                 }, delay)
             }
 
-            const hide = () => {
-                clearTimeout(this.timer)
-
-                if (open()) {
-                    tip.hidePopover()
-                }
-            }
-
             this.listen(trigger, 'pointerenter', (event) => event.pointerType === 'mouse' && show(HOVER_DELAY_MS))
-            this.listen(trigger, 'pointerleave', hide)
-            this.listen(trigger, 'pointerdown', hide)
+            this.listen(trigger, 'pointerleave', () => hide(LEAVE_DELAY_MS))
+            this.listen(trigger, 'pointerdown', () => hide())
             this.listen(trigger, 'focusin', () => trigger.matches(':focus-within:has(:focus-visible), :focus-visible') && show(0))
-            this.listen(trigger, 'focusout', hide)
+            this.listen(trigger, 'focusout', () => hide(LEAVE_DELAY_MS))
             this.listen(document, 'keydown', (event) => event.key === 'Escape' && hide())
         },
 
@@ -51,6 +68,11 @@ document.addEventListener('alpine:init', () => {
 
         destroy() {
             clearTimeout(this.timer)
+
+            if (visible === this.$el) {
+                visible = null
+            }
+
             this.listeners.forEach((remove) => remove())
         },
     }))