fix(e2e): parametrize reply line count and improve scroll behavior

packages/app/e2e/agent-bottom-anchor.spec.ts

@@ -104,6 +104,7 @@ test("sticky mode stays pinned through composer growth and viewport resize, but
       cwd: repo.path,
       title: `bottom-anchor-sticky-${Date.now()}`,
       turnCount: 10,
+      lineCount: 24,
     });
 
     await page.setViewportSize({ width: 1320, height: 920 });
@@ -123,7 +124,7 @@ test("sticky mode stays pinned through composer growth and viewport resize, but
     await expectNearBottom(page);
     await expect(page.getByTestId("scroll-to-bottom-button")).toHaveCount(0);
 
-    await page.setViewportSize({ width: 820, height: 760 });
+    await page.setViewportSize({ width: 1040, height: 760 });
     await expect(page.getByTestId(`workspace-tab-agent_${agent.id}`).first()).toBeVisible({
       timeout: 30000,
     });

packages/app/e2e/helpers/agent-bottom-anchor.ts

@@ -66,17 +66,17 @@ function buildReplyBlock(label: string, lineCount = 14): string {
   }).join("\n");
 }
 
-function buildProtocolMessage(label: string): string {
+function buildProtocolMessage(label: string, lineCount = 14): string {
   return [
     "For every message in this chat, reply with exactly the text after the final line `REPLY:`.",
     "Do not add extra words, bullets, markdown fences, or tool calls.",
     "REPLY:",
-    buildReplyBlock(label),
+    buildReplyBlock(label, lineCount),
   ].join("\n");
 }
 
-function buildReplyMessage(label: string): string {
+function buildReplyMessage(label: string, lineCount = 14): string {
-  return ["REPLY:", buildReplyBlock(label)].join("\n");
+  return ["REPLY:", buildReplyBlock(label, lineCount)].join("\n");
 }
 
 export function createReplyTurn(label: string): {
@@ -124,9 +124,11 @@ export async function seedBottomAnchorAgent(input: {
   cwd: string;
   title?: string;
   turnCount?: number;
+  lineCount?: number;
 }): Promise<SeededAgent> {
   const title = input.title ?? `bottom-anchor-${Date.now()}`;
   const turnCount = Math.max(3, input.turnCount ?? 5);
+  const lineCount = Math.max(14, input.lineCount ?? 14);
   const created = await input.client.createAgent({
     provider: "codex",
     model: "gpt-5.1-codex-mini",
@@ -134,7 +136,7 @@ export async function seedBottomAnchorAgent(input: {
     modeId: "full-access",
     cwd: input.cwd,
     title,
-    initialPrompt: buildProtocolMessage(`${title}-turn-00`),
+    initialPrompt: buildProtocolMessage(`${title}-turn-00`, lineCount),
   });
   const initialFinish = await input.client.waitForFinish(created.id, 120000);
   if (initialFinish.status !== "idle") {
@@ -143,11 +145,11 @@ export async function seedBottomAnchorAgent(input: {
     );
   }
 
-  let expectedTailText = buildReplyBlock(`${title}-turn-00`);
+  let expectedTailText = buildReplyBlock(`${title}-turn-00`, lineCount);
   for (let index = 1; index < turnCount; index += 1) {
     const label = `${title}-turn-${index.toString().padStart(2, "0")}`;
-    expectedTailText = buildReplyBlock(label);
+    expectedTailText = buildReplyBlock(label, lineCount);
-    await input.client.sendAgentMessage(created.id, buildReplyMessage(label));
+    await input.client.sendAgentMessage(created.id, buildReplyMessage(label, lineCount));
     const finish = await input.client.waitForFinish(created.id, 120000);
     if (finish.status !== "idle") {
       throw new Error(
@@ -209,36 +211,27 @@ export async function readScrollMetrics(page: Page): Promise<ScrollMetrics> {
 export async function scrollUpFromBottom(page: Page, pixels: number): Promise<void> {
   const scrollViewport = getVisibleChatScroll(page);
   await expect(scrollViewport).toHaveCount(1, { timeout: 30000 });
-  const targetDistanceFromBottom = Math.max(
+  let remaining = Math.max(0, pixels);
-    NEAR_BOTTOM_THRESHOLD_PX + 24,
+  while (remaining > 0) {
-    Math.max(0, pixels)
+    const delta = Math.min(240, remaining);
-  );
+    await scrollViewport.evaluate((element: Element, step: number) => {
-  await scrollViewport.evaluate(
+      const scrollContainer = element as HTMLElement;
-    (root: Element, input: { targetDistanceFromBottom: number }) => {
+      scrollContainer.dispatchEvent(
-      const candidates = [root, ...Array.from(root.querySelectorAll("*"))]
+        new WheelEvent("wheel", {
-        .filter((element): element is HTMLElement => element instanceof HTMLElement)
+          deltaY: -step,
-        .filter((element) => {
+          bubbles: true,
-          const tagName = element.tagName.toLowerCase();
+          cancelable: true,
-          const isEditable =
+        })
-            tagName === "textarea" ||
+      );
-            tagName === "input" ||
+      scrollContainer.scrollTop = Math.max(0, scrollContainer.scrollTop - step);
-            element.getAttribute("contenteditable") === "true";
+      scrollContainer.dispatchEvent(new Event("scroll", { bubbles: true }));
-          return !isEditable && element.scrollHeight - element.clientHeight > 1;
+    }, delta);
-        });
+    remaining -= delta;
-      const scrollElement =
+
-        candidates.sort(
+    if ((await readScrollMetrics(page)).distanceFromBottom > NEAR_BOTTOM_THRESHOLD_PX) {
-          (left, right) =>
+      return;
-            right.scrollHeight -
+    }
-            right.clientHeight -
+  }
-            (left.scrollHeight - left.clientHeight)
-        )[0] ?? (root as HTMLElement);
-      const maxOffset = Math.max(0, scrollElement.scrollHeight - scrollElement.clientHeight);
-      const nextOffset = Math.max(0, maxOffset - input.targetDistanceFromBottom);
-      scrollElement.scrollTop = nextOffset;
-      scrollElement.dispatchEvent(new Event("scroll", { bubbles: true }));
-    },
-    { targetDistanceFromBottom }
-  );
 }
 
 export async function waitForAgentReady(page: Page, expectedTailText?: string): Promise<void> {