From 1f12ee95a1a61651a726cbd5db97c63a793eaf57 Mon Sep 17 00:00:00 2001
From: Mohamed Boudra <boudra.moha@gmail.com>
Date: Thu, 15 Oct 2026 18:35:05 +0200
Subject: [PATCH] test(markdown): require growth while holding a streaming
 paragraph

---
 .../browser/agent-timeline-scroll-smoothness.spec.ts   |  4 ++++
 .../e2e/support/helpers/timeline-scroll-smoothness.ts  | 10 +++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/packages/app/e2e/browser/agent-timeline-scroll-smoothness.spec.ts b/packages/app/e2e/browser/agent-timeline-scroll-smoothness.spec.ts
index f3cddf3617..d5dd99e43f 100644
--- a/packages/app/e2e/browser/agent-timeline-scroll-smoothness.spec.ts
+++ b/packages/app/e2e/browser/agent-timeline-scroll-smoothness.spec.ts
@@ -156,6 +156,10 @@ test("reserves image space before its response arrives", async ({ page }, testIn
 test("holds a paragraph still while a mixed response streams and completes", async ({ page }) => {
   await withStreamingReader(async (agent) => {
     const reading = await holdParagraphThroughCompletion(page, agent);
+    expect(
+      reading.textGrowth,
+      "the held reader must observe an actively growing response",
+    ).toBeGreaterThan(1000);
     expect(
       reading.maxFollowGap,
       "follow-bottom must catch each streamed commit before the next frame",
diff --git a/packages/app/e2e/support/helpers/timeline-scroll-smoothness.ts b/packages/app/e2e/support/helpers/timeline-scroll-smoothness.ts
index 1b7522e54c..dbbbd8e7a3 100644
--- a/packages/app/e2e/support/helpers/timeline-scroll-smoothness.ts
+++ b/packages/app/e2e/support/helpers/timeline-scroll-smoothness.ts
@@ -100,11 +100,16 @@ export async function holdParagraphThroughCompletion(page: Page, agent: MockAgen
   const paragraph = page.getByRole("heading", { name: "Long section 3", exact: true });
   await paragraph.waitFor({ state: "attached" });
   const recording = await paragraph.evaluateHandle((heading) => {
+    if (!document.querySelector('[data-testid="turn-working-indicator"]')) {
+      throw new Error("The stream completed before the reader detached");
+    }
     const viewport = document.querySelector<HTMLElement>('[data-testid="agent-chat-scroll"]')!;
     const clip = viewport.getBoundingClientRect();
     viewport.scrollTop += heading.getBoundingClientRect().y - (clip.top + clip.height / 2);
     const baseline = heading.getBoundingClientRect().y;
-    const result = { maxDrift: 0, retained: true, done: false };
+    const initialTextLength = heading.closest('[data-testid="assistant-message"]')!.textContent!
+      .length;
+    const result = { maxDrift: 0, retained: true, textGrowth: 0, done: false };
     let stableAt = performance.now();
     let signature = "";
     const frame = (now: number) => {
@@ -112,6 +117,9 @@ export async function holdParagraphThroughCompletion(page: Page, agent: MockAgen
       const current = [...document.querySelectorAll("h2")].find(
         (n) => n.textContent === "Long section 3",
       );
+      const textLength =
+        current?.closest('[data-testid="assistant-message"]')?.textContent?.length ?? 0;
+      result.textGrowth = Math.max(result.textGrowth, textLength - initialTextLength);
       if (current)
         result.maxDrift = Math.max(
           result.maxDrift,