diff --git a/.agents/notes/implemented/feature/2026-08-03-web-search-source-scroll.i18n.yaml b/.agents/notes/implemented/feature/2026-08-03-web-search-source-scroll.i18n.yaml
index 923146cc2b..1e08a3f091 100644
--- a/.agents/notes/implemented/feature/2026-08-03-web-search-source-scroll.i18n.yaml
+++ b/.agents/notes/implemented/feature/2026-08-03-web-search-source-scroll.i18n.yaml
@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write .agents/notes/implemented/feature/2026-08-03-web-search-source-scroll.md
-2026-08-03-web-search-source-scroll.md: 8ec9aee890015ecc1360b447a8bcee5585365e86
-2026-08-03-web-search-source-scroll.zh.md: a9cf64d421e972ec80f1746489bac2eb15d0dc50
+2026-08-03-web-search-source-scroll.md: fe98aca07fae9b6b3e612ae432f14cf5db462461
+2026-08-03-web-search-source-scroll.zh.md: 38573647d59d659c8cdec53a42913848d268c6be
diff --git a/.agents/notes/implemented/feature/2026-08-03-web-search-source-scroll.md b/.agents/notes/implemented/feature/2026-08-03-web-search-source-scroll.md
index 8ec9aee890..fe98aca07f 100644
--- a/.agents/notes/implemented/feature/2026-08-03-web-search-source-scroll.md
+++ b/.agents/notes/implemented/feature/2026-08-03-web-search-source-scroll.md
@@ -36,6 +36,8 @@ Every source the tool returned is always in the DOM, so no source the view carri
 
 `packages/client/ui-primitives/tests/web-block.spec.tsx` drops the collapse cases (head/tail slice, expand-on-click, collapsed-tail numbering, expander-out-of-numbering, head-alone, default cap) and adds: a 30-source card renders all 30 `<li>` with no `[aria-expanded]` and no `<button>`, every `<ol>` child is a source `<li>`, and `<li value>` numbers 1..N contiguously. `packages/client/ui-conversation/tests/web-card.spec.tsx` drops the `CHAT_WEB_MAX_SOURCES` cap assertion; the WebRow expansion test still asserts the card shows every source field. The `packages/web/tool-web` tests are unchanged — the model side did not move.
 
+jsdom resolves no CSS Modules layout, so it reports `scrollHeight === clientHeight` for every element and cannot witness the scroll at all. The geometry is pinned in the assembled browser instead, by `apps/web/tests/web-search-round.e2e.ts`: its deterministic search double returns 12 provider results, each with a title, a citation snippet, and a date. That first pins the seam's cap end to end in a real composition — the shipped `searchMaxResults` keeps 8, the model-visible render text carries the 8 kept titles and none of the 4 dropped URLs plus `(Showing the first 8 sources. Refine the query for more.)`, and `meta.truncated` is true. A case after the aria golden then expands the `web_search` row and asserts on the card's `<ol>`: 8 `<li>`, no `<button>` anywhere in the card, the `来源列表已截断` indicator visible, and computed `max-height: 320px` with `overflow-y: auto` over `scrollHeight` 574 against `clientHeight` 320. Neither the recorded stream nor the aria golden moved: replay is a positional cursor over the fixture's `assistant/chunk` entries and the search double is a separate local endpoint the provider reaches by `fetch`, while the card is collapsed at capture time so its `<ol>` is out of the DOM and the summary row carries no source count.
+
 ## Related
 
 - [Web result card](2026-07-30-web-result-card.md) — the `card: 'web'` render-intent arm and `presentationMeta` route this card consumes; the source of the capped-once list.
diff --git a/.agents/notes/implemented/feature/2026-08-03-web-search-source-scroll.zh.md b/.agents/notes/implemented/feature/2026-08-03-web-search-source-scroll.zh.md
index a9cf64d421..38573647d5 100644
--- a/.agents/notes/implemented/feature/2026-08-03-web-search-source-scroll.zh.md
+++ b/.agents/notes/implemented/feature/2026-08-03-web-search-source-scroll.zh.md
@@ -36,6 +36,8 @@ Status: implemented
 
 `packages/client/ui-primitives/tests/web-block.spec.tsx` 删去折叠相关用例（首尾切片、点击展开、折叠尾部编号、展开器不计入编号、仅首部、默认上限），并新增：一个 30 条来源的卡片渲染出全部 30 个 `<li>`，无 `[aria-expanded]`、无 `<button>`，每个 `<ol>` 子元素都是一条来源 `<li>`，且 `<li value>` 从 1 到 N 连续编号。`packages/client/ui-conversation/tests/web-card.spec.tsx` 删去 `CHAT_WEB_MAX_SOURCES` 上限断言；WebRow 展开测试仍断言卡片展示每一个来源字段。`packages/web/tool-web` 的测试不变——模型侧未曾移动。
 
+jsdom 不解析 CSS Modules 布局，对任何元素都报 `scrollHeight === clientHeight`，因此它根本无从见证这次滚动。几何改由组装态浏览器钉住，位于 `apps/web/tests/web-search-round.e2e.ts`：其确定性 search double 返回 12 条 provider 结果，每条带标题、引用摘录与日期。这首先在真实组合里端到端钉住 seam 的裁剪——出厂 `searchMaxResults` 保留 8 条，面向模型的 render 文本含这 8 条标题、不含被丢弃的 4 条 URL，并含 `(Showing the first 8 sources. Refine the query for more.)`，`meta.truncated` 为 true。随后位于 aria golden 之后的一个用例展开 `web_search` 行，对卡片的 `<ol>` 断言：8 个 `<li>`、卡片内任何位置都没有 `<button>`、`来源列表已截断` 指示可见，以及计算样式 `max-height: 320px` 与 `overflow-y: auto`，`scrollHeight` 为 574、`clientHeight` 为 320。录制的模型流与 aria golden 都未变动：replay 是对 fixture 中 `assistant/chunk` 条目的位置游标，而 search double 是 provider 经 `fetch` 抵达的另一个本地端点；捕获时卡片处于折叠状态，其 `<ol>` 不在 DOM 中，摘要行也不携带来源数量。
+
 ## Related
 
 - [Web result card](2026-07-30-web-result-card.md) —— 本卡片消费的 `card: 'web'` 渲染意图分支与 `presentationMeta` 路由；那份裁剪过一次的列表的来源。
diff --git a/apps/web/tests/web-search-round.e2e.ts b/apps/web/tests/web-search-round.e2e.ts
index 53d0ae54b3..92e75c421f 100644
--- a/apps/web/tests/web-search-round.e2e.ts
+++ b/apps/web/tests/web-search-round.e2e.ts
@@ -26,7 +26,37 @@ const QUERY = 'DeepSeek Harness snapshot search'
 const PROMPT = `Use web_search to search exactly "${QUERY}". Then reply exactly SEARCH_DONE and stop.`
 const SEARCH_CREDENTIAL_REF = credentialRef('DSH_WEB_SEARCH_E2E_KEY')
 const SEARCH_CREDENTIAL = 'snapshot-search-key'
-const RESULT_URL = 'https://docs.example.test/search'
+
+/**
+ * Provider results the double returns, exceeding the shipped `searchMaxResults`
+ * so the seam's cap and the card's scroll container are both exercised. Each row
+ * carries a title, a snippet, and a date, so 8 kept rows exceed the `.sources`
+ * 320px max-height.
+ */
+const PROVIDER_RESULT_COUNT = 12
+
+/** One provider result's URL, by 1-based provider order. */
+function resultUrl(ordinal: number): string {
+  return `https://docs.example.test/search/${ordinal}`
+}
+
+/** One provider result's title, by 1-based provider order. */
+function resultTitle(ordinal: number): string {
+  return `Snapshot Search Result ${ordinal}`
+}
+
+/** One provider result's citation excerpt, by 1-based provider order. */
+function resultSnippet(ordinal: number): string {
+  return `Snapshot search excerpt ${ordinal}: the harness replays this source list from a local endpoint.`
+}
+
+/** One provider result's `page_age`, by 1-based provider order (July 2026 days 01..12). */
+function resultPageAge(ordinal: number): string {
+  return `2026-07-${String(ordinal).padStart(2, '0')}`
+}
+
+/** The 1-based provider ordinals, in provider order. */
+const RESULT_ORDINALS = Array.from({ length: PROVIDER_RESULT_COUNT }, (_value, index) => index + 1)
 
 interface CapturedSearchRequest {
   path: string
@@ -51,21 +81,21 @@ async function startSearchServer(captured: CapturedSearchRequest[]): Promise<{ s
         content: [
           {
             type: 'text',
-            text: 'Found one source.',
-            citations: [{
+            text: `Found ${PROVIDER_RESULT_COUNT} sources.`,
+            citations: RESULT_ORDINALS.map(ordinal => ({
               type: 'web_search_result_location',
-              url: RESULT_URL,
-              cited_text: 'Snapshot search excerpt.',
-            }],
+              url: resultUrl(ordinal),
+              cited_text: resultSnippet(ordinal),
+            })),
           },
           {
             type: 'web_search_tool_result',
-            content: [{
+            content: RESULT_ORDINALS.map(ordinal => ({
               type: 'web_search_result',
-              url: RESULT_URL,
-              title: 'Snapshot Search Result',
-              page_age: '2026-07-31',
-            }],
+              url: resultUrl(ordinal),
+              title: resultTitle(ordinal),
+              page_age: resultPageAge(ordinal),
+            })),
           },
         ],
       }))
@@ -142,7 +172,7 @@ describe('web e2e: shipped default web search', () => {
     if (MODE === 'record') await recordFixture(scaffold, sessionId, FIXTURE)
   }, 200_000)
 
-  it.skipIf(MODE === 'record')('uses the real provider and persists the structured result', () => {
+  it.skipIf(MODE === 'record')('uses the real provider and persists the capped structured result', () => {
     expect(searchRequests).toHaveLength(1)
     expect(searchRequests[0]).toMatchObject({
       path: '/messages',
@@ -178,16 +208,27 @@ describe('web e2e: shipped default web search', () => {
     if (searchResult === undefined) throw new Error('web_search produced no durable result')
     const content = searchResult.data.message.content[0]
     expect(content.isError).toBe(false)
-    expect(content.content.filter(block => block.type === 'text').map(block => block.text).join(''))
-      .toContain(`[Snapshot Search Result](${RESULT_URL})`)
+    const rendered = content.content.filter(block => block.type === 'text').map(block => block.text).join('')
+    // The seam caps the provider's list at the shipped searchMaxResults before
+    // the tool renders it, so the kept prefix is model-visible and the dropped
+    // suffix is not.
+    for (const ordinal of RESULT_ORDINALS.slice(0, WEB_SEARCH_MAX_RESULTS)) {
+      expect(rendered).toContain(`[${resultTitle(ordinal)}](${resultUrl(ordinal)})`)
+    }
+    for (const ordinal of RESULT_ORDINALS.slice(WEB_SEARCH_MAX_RESULTS)) {
+      expect(rendered).not.toContain(resultUrl(ordinal))
+    }
+    expect(rendered).toContain(
+      `(Showing the first ${WEB_SEARCH_MAX_RESULTS} sources. Refine the query for more.)`,
+    )
     expect(searchResult.data.meta).toMatchObject({
-      sources: [{
-        url: RESULT_URL,
-        title: 'Snapshot Search Result',
-        snippet: 'Snapshot search excerpt.',
-        publishedAt: '2026-07-31',
-      }],
-      truncated: false,
+      sources: RESULT_ORDINALS.slice(0, WEB_SEARCH_MAX_RESULTS).map(ordinal => ({
+        url: resultUrl(ordinal),
+        title: resultTitle(ordinal),
+        snippet: resultSnippet(ordinal),
+        publishedAt: resultPageAge(ordinal),
+      })),
+      truncated: true,
     })
   })
 
@@ -200,6 +241,36 @@ describe('web e2e: shipped default web search', () => {
     await compareOrRefreshGolden(UI_EXPECTED, snapshot, MODE)
   })
 
+  it.skipIf(MODE === 'record')('scrolls the capped source list inside the fixed-height container', async () => {
+    onTestFailed(() => saveFailureShot(page, 'web-e2e-search-sources-scroll'))
+    const row = page.locator('[data-tool="web_search"] [data-expandable]').first()
+    await row.click()
+    await expect.poll(() => row.getAttribute('aria-expanded'), { timeout: 5_000 }).toBe('true')
+
+    const card = page.locator('[data-web="search"]')
+    const sources = card.locator('ol')
+    await sources.waitFor({ timeout: 10_000 })
+    // The card draws exactly the sources the model saw: the seam's cap, not the
+    // provider's list length.
+    expect(await sources.locator('li').count()).toBe(WEB_SEARCH_MAX_RESULTS)
+    // The list is complete in the DOM, so the card carries no expand control.
+    expect(await card.locator('button').count()).toBe(0)
+    expect(await card.getByText('来源列表已截断').isVisible()).toBe(true)
+
+    const geometry = await sources.evaluate((element) => {
+      const computed = getComputedStyle(element)
+      return {
+        maxHeight: computed.maxHeight,
+        overflowY: computed.overflowY,
+        scrollHeight: element.scrollHeight,
+        clientHeight: element.clientHeight,
+      }
+    })
+    expect(geometry.maxHeight).toBe('320px')
+    expect(geometry.overflowY).toBe('auto')
+    expect(geometry.scrollHeight).toBeGreaterThan(geometry.clientHeight)
+  })
+
   it.skipIf(MODE === 'record')('stayed clean and kept the exact fixture inventory', async () => {
     expect(tripwire.pageErrors).toEqual([])
     expect(tripwire.warnings).toEqual([])