Tooltips after one second, and at once for the next button

From the development repository at b7ffe0e.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

client/js/tooltip.js

@@ -11,7 +11,18 @@
 
 import { trace } from './log.js';
 
-const DELAY_MS = 2000;
+/**
+ * How long the pointer must have been in a button before its tooltip
+ * appears: the time in the button, movement inside it not counting
+ * (Andy, 2026-10-11: one second; two until then, one until 2026-10-06).
+ */
+export const DELAY_MS = 1000;
+/**
+ * The neighbour rule: within this long after a tooltip was shown, the
+ * next button's tooltip appears at once, so that reading a row of
+ * buttons costs one wait, not one per button.  A press or a key ends it.
+ */
+export const WARM_MS = 1000;
 const GAP_PX = 6;
 
 /** @type {HTMLElement | null} */
@@ -20,6 +31,8 @@ let tooltip = null;
 let timer = null;
 /** @type {Element | null} */
 let shownFor = null;
+/** When a tooltip was last showing, for the neighbour rule. */
+let warmUntil = -Infinity;
 
 /**
  * @param {EventTarget | null} target
@@ -49,10 +62,13 @@ function show(element) {
   tooltip.style.top = `${box.bottom + GAP_PX}px`;
 }
 
-function hide() {
+/** @param {boolean} [cold]  Whether the neighbour rule ends here too. */
+function hide(cold = false) {
   if (timer !== null) clearTimeout(timer);
   timer = null;
+  if (shownFor) warmUntil = performance.now() + WARM_MS;
   shownFor = null;
+  if (cold) warmUntil = -Infinity;
   if (tooltip) tooltip.hidden = true;
 }
 
@@ -69,11 +85,12 @@ export function enableTooltips() {
     if (element === shownFor) return;
     hide();
     trace(`Hover: ${event.pointerType} over ${element.textContent?.trim() || element.id}`);
+    const wait = performance.now() < warmUntil ? 0 : DELAY_MS;
     timer = setTimeout(() => {
       timer = null;
       trace(`Tooltip: ${element.textContent?.trim() || element.id}`);
       show(element);
-    }, DELAY_MS);
+    }, wait);
   });
   document.addEventListener('pointerleave', (event) => {
     if (timer !== null || shownFor) trace(`Hover: ${event.pointerType} left the document`);
@@ -85,14 +102,14 @@ export function enableTooltips() {
   let pressedAt = -Infinity;
   document.addEventListener('pointerdown', () => {
     pressedAt = performance.now();
-    hide();
+    hide(true);
   });
   document.addEventListener('focusin', (event) => {
     if (performance.now() - pressedAt < 500) return;
     const element = helpElement(event.target);
     if (element) show(element);
   });
-  document.addEventListener('focusout', hide);
+  document.addEventListener('focusout', () => hide());
   // Typing means the user's attention is on the keys, not the tooltip.
-  document.addEventListener('keydown', hide);
+  document.addEventListener('keydown', () => hide(true));
 }