From 9f684850362f3a3dd4a80b2695f541330949061d Mon Sep 17 00:00:00 2001
From: Badcuban <108198679+badcuban@users.noreply.github.com>
Date: Thu, 22 Oct 2026 02:29:56 -0400
Subject: [PATCH] test(web): the text-selection list tests scroll the way a
 reader does

The two text-selection tests on the real chat list wrote scrollTop
directly to bring a word into view. The list hears a scroll a frame
later; a row it measured in between (common on a busy CI runner) let its
follow-the-end logic snap back to the bottom, the word left view and its
selection dropped, so the Copy button never appeared.

The helper now sends a wheel event before each scroll, as a real wheel
does, which tells the list the reader left its end.
---
 .../chat/MessagesTimeline.real-list.browser.tsx     | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/apps/web/src/components/chat/MessagesTimeline.real-list.browser.tsx b/apps/web/src/components/chat/MessagesTimeline.real-list.browser.tsx
index 17b390b22..30c352dd3 100644
--- a/apps/web/src/components/chat/MessagesTimeline.real-list.browser.tsx
+++ b/apps/web/src/components/chat/MessagesTimeline.real-list.browser.tsx
@@ -1427,17 +1427,26 @@ function dragSelectWord(messageId: string, word: string) {
   throw new Error(`"${word}" is not in ${messageId}`);
 }
 
+// Scrolls the list by `delta` the way a reader's wheel does: the wheel comes
+// first and tells the list the reader left its end. A bare scrollTop write
+// does not. The list hears that scroll a frame later (longer on a busy
+// machine), and a row it measures in between snaps it back to the end.
+function wheelScroll(list: HTMLElement, delta: number) {
+  list.dispatchEvent(new WheelEvent("wheel", { bubbles: true, deltaY: delta }));
+  list.scrollTop += delta;
+}
+
 // Scrolls `step` pixels at a time until the list draws message-51, then puts
 // its word in the middle of the list. A saved scroll position cannot stand in
 // for this: the list measures rows as they come into view, and every row it
 // measures moves the ones below it.
 async function scrollPelicanIntoView(list: HTMLElement, step: number) {
   for (let count = 0; count < 40 && !wordRect("message-51", "pelican"); count += 1) {
-    list.scrollTop += step;
+    wheelScroll(list, step);
     await new Promise((resolve) => setTimeout(resolve, 50));
   }
   const listTop = list.getBoundingClientRect().top;
-  list.scrollTop += wordRect("message-51", "pelican")!.top - listTop - 180;
+  wheelScroll(list, wordRect("message-51", "pelican")!.top - listTop - 180);
   await new Promise((resolve) => setTimeout(resolve, 200));
 }