From 870c28aa6550a8422517f97bcf54a80abb5a14ab Mon Sep 17 00:00:00 2001
From: Kun Ren <renkun@outlook.com>
Date: Tue, 6 Oct 2026 22:54:28 +0800
Subject: [PATCH 1/5] refactor(viewer): share list tree controls with
 Interactive cells

---
 src/listViewer.ts | 229 +++++++++++++++++++++++++++++++++++-----------
 src/session.ts    |  92 ++-----------------
 2 files changed, 184 insertions(+), 137 deletions(-)

diff --git a/src/listViewer.ts b/src/listViewer.ts
index a1aaa09e8..c450c0740 100644
--- a/src/listViewer.ts
+++ b/src/listViewer.ts
@@ -1,3 +1,5 @@
+/// <reference lib="dom" />
+
 export interface ListViewNavigation {
     title: string;
     path: number[];
@@ -6,42 +8,55 @@ export interface ListViewNavigation {
     vector?: boolean;
 }
 
-/** Script shared by the list webview and its interaction tests. */
-export function getListViewerScript(documentGeneration: number, initial: ListViewNavigation = {
-    title: '', path: [], breadcrumbs: [{ label: '', path: [] }],
-}): string {
-    return `
-    const vscode = acquireVsCodeApi();
-    const documentGeneration = ${documentGeneration};
-    const pending = new Map();
-    let nextRequestId = 0;
-    const list = document.getElementById('list');
-    const back = document.getElementById('back');
-    const breadcrumbs = document.getElementById('breadcrumbs');
-    const navigationStatus = document.getElementById('navigation-status');
-    const pages = new Map();
-    const history = [];
-    let current;
-    let navigating = false;
+export interface ListViewPage {
+    children: { label: string; str: string; index: number; viewable?: boolean; has_children?: boolean }[];
+    next_start?: number | null;
+}
+export interface ListViewReply extends Partial<ListViewPage> {
+    requestId: number;
+    error?: string;
+    navigation?: ListViewNavigation;
+}
+export interface ListViewer {
+    reply(message: ListViewReply): void;
+    dispose(): void;
+    navigation(): ListViewNavigation;
+}
 
-    function showNavigation(navigation, goingBack = false) {
+/** Shared tree, paging and navigation for the panel and Interactive cells. */
+export function createListViewer(
+    { root, list, back, breadcrumbs, navigationStatus }: {
+        root: HTMLElement; list: HTMLElement; back: HTMLButtonElement; breadcrumbs: HTMLElement; navigationStatus: HTMLElement;
+    },
+    initial: ListViewNavigation,
+    request: (message: { message: string; path: number[]; index?: number; start?: number }) => number,
+    initialPage?: ListViewPage,
+    live = true,
+): ListViewer {
+    const pending = new Map<number, (message: ListViewReply) => void>();
+    const pages = new Map<string, { element: HTMLElement; scrollTop: number; loader: { loadOnce(): void } }>();
+    const history: ListViewNavigation[] = [];
+    let current: ListViewNavigation;
+    let navigating = false;
+    let disposed = false;
+    function showNavigation(navigation: ListViewNavigation, goingBack = false): void {
         const key = JSON.stringify(navigation.path);
         if (current) {
-            pages.get(JSON.stringify(current.path)).scrollTop = list.scrollTop;
-            if (goingBack) history.pop();
-            else if (JSON.stringify(current.path) !== key) history.push(current);
+            pages.get(JSON.stringify(current.path))!.scrollTop = list.scrollTop;
+            if (goingBack) { history.pop(); }
+            else if (JSON.stringify(current.path) !== key) { history.push(current); }
         }
         current = navigation;
-        document.body.classList.toggle('vector', !!navigation.vector);
+        root.classList.toggle('vector', !!navigation.vector);
         let page = pages.get(key);
         if (!page) {
             const element = document.createElement('div');
-            page = { element, scrollTop: 0, loader: createPage(element, navigation.path, navigation.vector) };
+            page = { element, scrollTop: 0, loader: createPage(element, navigation.path, navigation.vector, pages.size === 0 ? initialPage : undefined) };
             pages.set(key, page);
         }
         list.replaceChildren(page.element);
         list.scrollTop = page.scrollTop;
-        back.disabled = history.length === 0;
+        back.disabled = !live || history.length === 0;
         breadcrumbs.replaceChildren();
         navigation.breadcrumbs.forEach((crumb, index) => {
             if (index) {
@@ -55,18 +70,21 @@ export function getListViewerScript(documentGeneration: number, initial: ListVie
             item.className = 'breadcrumb';
             item.textContent = crumb.label;
             item.title = crumb.label;
-            if (isCurrent) item.setAttribute('aria-current', 'page');
-            else item.addEventListener('click', () => navigate('listview/navigate', { path: crumb.path }));
+            if (isCurrent) { item.setAttribute('aria-current', 'page'); }
+            else {
+                (item as HTMLButtonElement).disabled = !live;
+                item.addEventListener('click', () => navigate('listview/navigate', { path: crumb.path }));
+            }
             breadcrumbs.appendChild(item);
         });
         page.loader.loadOnce();
     }
 
-    function navigate(message, params, goingBack = false) {
-        if (navigating) return;
+    function navigate(message: string, params: { path: number[]; index?: number }, goingBack = false): void {
+        if (disposed || !live || navigating) { return; }
         navigating = true;
         navigationStatus.textContent = '';
-        const requestId = ++nextRequestId;
+        const requestId = request({ message, ...params });
         pending.set(requestId, (response) => {
             navigating = false;
             if (response.error) {
@@ -75,14 +93,13 @@ export function getListViewerScript(documentGeneration: number, initial: ListVie
                 showNavigation(response.navigation, goingBack);
             }
         });
-        vscode.postMessage({ message, documentGeneration, requestId, ...params });
     }
 
     back.addEventListener('click', () => {
-        if (history.length) navigate('listview/navigate', { path: history[history.length - 1].path }, true);
+        if (history.length) { navigate('listview/navigate', { path: history[history.length - 1].path }, true); }
     });
 
-    function createPage(container, path, vector = false) {
+    function createPage(container: HTMLElement, path: number[], vector = false, savedPage?: ListViewPage): { loadOnce(): void } {
         const rows = document.createElement('div');
         const more = document.createElement('button');
         more.className = 'load-more';
@@ -92,27 +109,26 @@ export function getListViewerScript(documentGeneration: number, initial: ListVie
         container.appendChild(rows);
         container.appendChild(more);
         container.appendChild(status);
-        let nextStart = 1;
+        let nextStart: number | null = 1;
         let loading = false;
         let loaded = false;
 
-        function loadPage() {
-            if (loading || nextStart === null) return;
+        function loadPage(): void {
+            if (disposed || (!live && !savedPage) || loading || nextStart === null) { return; }
             loading = true;
             more.disabled = true;
             more.textContent = 'Loading…';
             status.textContent = '';
-            const requestId = ++nextRequestId;
-            pending.set(requestId, (message) => {
+            const receive = (message: ListViewReply): void => {
                 loading = false;
-                more.disabled = false;
+                more.disabled = !live;
                 if (message.error) {
                     status.textContent = message.error;
                     more.textContent = 'Retry';
                     return;
                 }
                 loaded = true;
-                for (const item of message.children) {
+                for (const item of message.children ?? []) {
                     const expandable = item.has_children;
                     const entry = document.createElement(expandable ? 'details' : 'div');
                     const row = document.createElement(expandable ? 'summary' : 'div');
@@ -135,6 +151,7 @@ export function getListViewerScript(documentGeneration: number, initial: ListVie
                     if (item.viewable) {
                         const button = document.createElement('button');
                         button.title = 'View';
+                        button.disabled = !live;
                         button.setAttribute('aria-label', 'View ' + item.label);
                         const icon = document.createElement('span');
                         icon.className = 'codicon codicon-open-preview';
@@ -152,9 +169,10 @@ export function getListViewerScript(documentGeneration: number, initial: ListVie
                         const children = document.createElement('div');
                         children.className = 'children';
                         entry.appendChild(children);
-                        let page;
+                        let page: { loadOnce(): void } | undefined;
                         entry.addEventListener('toggle', () => {
-                            if (entry.open) {
+                            if ((entry as HTMLDetailsElement).open && !live && !page) { (entry as HTMLDetailsElement).open = false; return; }
+                            if ((entry as HTMLDetailsElement).open) {
                                 page ??= createPage(children, [...path, item.index]);
                                 page.loadOnce();
                             }
@@ -166,22 +184,129 @@ export function getListViewerScript(documentGeneration: number, initial: ListVie
                 more.hidden = nextStart === null;
                 more.textContent = 'Load more';
                 status.textContent = rows.childElementCount ? '' : 'No items';
-            });
-            vscode.postMessage({ message: 'listview/page', documentGeneration, requestId, path, start: nextStart });
+            };
+            if (savedPage) {
+                const page = savedPage; savedPage = undefined; receive({ ...page, requestId: 0 });
+            } else {
+                pending.set(request({ message: 'listview/page', path, start: nextStart }), receive);
+            }
         }
         more.addEventListener('click', loadPage);
-        return { loadOnce: () => { if (!loaded) loadPage(); } };
+        return { loadOnce: () => { if (!loaded) { loadPage(); } } };
     }
 
-    window.addEventListener('message', (event) => {
+    showNavigation(initial);
+    return {
+        navigation: () => current,
+        reply(message) {
+            const receive = pending.get(message.requestId);
+            if (receive) { pending.delete(message.requestId); receive(message); }
+        },
+        dispose() { disposed = true; pending.clear(); },
+    };
+}
+
+/** Script shared by the list webview and its interaction tests. */
+export function getListViewerScript(documentGeneration: number, initial: ListViewNavigation = {
+    title: '', path: [], breadcrumbs: [{ label: '', path: [] }],
+}): string {
+    return `
+    const vscode = acquireVsCodeApi();
+    const documentGeneration = ${documentGeneration};
+    let nextRequestId = 0;
+    const viewer = (${createListViewer.toString()})({
+        root: document.body, list: document.getElementById('list'), back: document.getElementById('back'),
+        breadcrumbs: document.getElementById('breadcrumbs'), navigationStatus: document.getElementById('navigation-status'),
+    }, ${JSON.stringify(initial).replace(/</g, '\\u003c')}, message => {
+        const requestId = ++nextRequestId;
+        vscode.postMessage({ ...message, documentGeneration, requestId });
+        return requestId;
+    });
+    window.addEventListener('message', event => {
         const message = event.data;
-        if (!['listview/page', 'listview/navigation'].includes(message.message) || message.documentGeneration !== documentGeneration) return;
-        const receive = pending.get(message.requestId);
-        if (receive) {
-            pending.delete(message.requestId);
-            receive(message);
-        }
+        if (['listview/page', 'listview/navigation'].includes(message.message) && message.documentGeneration === documentGeneration) viewer.reply(message);
     });
-    showNavigation(${JSON.stringify(initial).replace(/</g, '\\u003c')});
     `;
 }
+
+export const listViewerStyle = `
+    .r-list-viewer .list { flex: 1; min-height: 0; overflow: auto; }
+    .r-list-viewer .navigation {
+        display: flex;
+        align-items: center;
+        gap: 12px;
+        padding: 6px 8px;
+        min-height: 28px;
+        border-bottom: 1px solid var(--vscode-panel-border);
+        background: var(--vscode-breadcrumb-background, var(--vscode-editor-background));
+    }
+    .r-list-viewer .back { gap: 4px; padding: 4px 6px; flex-shrink: 0; border-radius: 3px; }
+    .r-list-viewer .back:disabled { opacity: 0.4; cursor: default; background: transparent; }
+    .r-list-viewer .codicon { flex-shrink: 0; }
+    .r-list-viewer .breadcrumbs {
+        display: flex;
+        align-items: center;
+        gap: 2px;
+        overflow-x: auto;
+        color: var(--vscode-breadcrumb-foreground);
+    }
+    .r-list-viewer .breadcrumb { padding: 4px; white-space: nowrap; border-radius: 3px; }
+    .r-list-viewer button.breadcrumb:hover { color: var(--vscode-breadcrumb-focusForeground); }
+    .r-list-viewer .breadcrumb[aria-current] { color: var(--vscode-breadcrumb-activeSelectionForeground); }
+    .r-list-viewer .navigation-status { padding: 0 8px; color: var(--vscode-errorForeground); }
+    .r-list-viewer .item {
+        display: flex;
+        align-items: center;
+        gap: 12px;
+        min-height: 28px;
+        padding: 2px 8px;
+    }
+    .r-list-viewer .item:hover {
+        background-color: var(--vscode-list-hoverBackground);
+        color: var(--vscode-list-hoverForeground);
+    }
+    .r-list-viewer summary.item { cursor: pointer; list-style: none; }
+    .r-list-viewer summary.item::-webkit-details-marker { display: none; }
+    .r-list-viewer .arrow { width: 16px; height: 16px; flex-shrink: 0; }
+    .r-list-viewer summary > .arrow {
+        color: var(--vscode-icon-foreground, currentColor);
+    }
+    .r-list-viewer details[open] > summary > .arrow { transform: rotate(90deg); }
+    .r-list-viewer .children { margin-left: 24px; }
+    .r-list-viewer button:focus-visible, .r-list-viewer summary:focus-visible { outline: 1px solid var(--vscode-focusBorder); }
+    .r-list-viewer .label {
+        min-width: 140px;
+        color: var(--vscode-symbolIcon-fieldForeground);
+        white-space: nowrap;
+    }
+    .r-list-viewer.vector .label {
+        min-width: 64px;
+    }
+    .r-list-viewer.vector .item {
+        gap: 8px;
+    }
+    .r-list-viewer .str {
+        flex: 1;
+        color: var(--vscode-descriptionForeground);
+        white-space: pre-wrap;
+    }
+    .r-list-viewer button {
+        display: flex;
+        align-items: center;
+        border: 0;
+        padding: 2px;
+        color: var(--vscode-foreground);
+        background: transparent;
+        cursor: pointer;
+        font: inherit;
+    }
+    .r-list-viewer button:hover {
+        background-color: var(--vscode-toolbar-hoverBackground);
+    }
+    .r-list-viewer .load-more {
+        margin: 8px;
+    }
+    .r-list-viewer .load-more[hidden] {
+        display: none;
+    }
+`;
diff --git a/src/session.ts b/src/session.ts
index 35403d329..ba9061849 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -19,7 +19,7 @@ import { resolveBackend, jgdEnabled, CommonPlotManager } from './plotViewer';
 import type { RSessionConnectionInfo } from './api';
 
 import { showWebView } from './webViewer';
-import { getListViewerScript, ListViewNavigation } from './listViewer';
+import { getListViewerScript, listViewerStyle, ListViewNavigation } from './listViewer';
 import { getDataViewerScript, getDataViewerStyle, getDataViewerToolbarHtml } from './dataViewer';
 import { getDataViewerColumnPanelHtml, getDataViewerColumnPanelScript, getDataViewerColumnPanelStyle } from './dataViewerColumnPanel';
 
@@ -1947,94 +1947,16 @@ export function getListHtml(
         font-family: var(--vscode-font-family);
         font-size: var(--vscode-font-size);
     }
-    #list { flex: 1; min-height: 0; overflow: auto; }
-    .navigation {
-        display: flex;
-        align-items: center;
-        gap: 12px;
-        padding: 6px 8px;
-        min-height: 28px;
-        border-bottom: 1px solid var(--vscode-panel-border);
-        background: var(--vscode-breadcrumb-background, var(--vscode-editor-background));
-    }
-    #back { gap: 4px; padding: 4px 6px; flex-shrink: 0; border-radius: 3px; }
-    #back:disabled { opacity: 0.4; cursor: default; background: transparent; }
-    .codicon { flex-shrink: 0; }
-    #breadcrumbs {
-        display: flex;
-        align-items: center;
-        gap: 2px;
-        overflow-x: auto;
-        color: var(--vscode-breadcrumb-foreground);
-    }
-    .breadcrumb { padding: 4px; white-space: nowrap; border-radius: 3px; }
-    button.breadcrumb:hover { color: var(--vscode-breadcrumb-focusForeground); }
-    .breadcrumb[aria-current] { color: var(--vscode-breadcrumb-activeSelectionForeground); }
-    #navigation-status { padding: 0 8px; color: var(--vscode-errorForeground); }
-    .item {
-        display: flex;
-        align-items: center;
-        gap: 12px;
-        min-height: 28px;
-        padding: 2px 8px;
-    }
-    .item:hover {
-        background-color: var(--vscode-list-hoverBackground);
-        color: var(--vscode-list-hoverForeground);
-    }
-    summary.item { cursor: pointer; list-style: none; }
-    summary.item::-webkit-details-marker { display: none; }
-    .arrow { width: 16px; height: 16px; flex-shrink: 0; }
-    summary > .arrow {
-        color: var(--vscode-icon-foreground, currentColor);
-    }
-    details[open] > summary > .arrow { transform: rotate(90deg); }
-    .children { margin-left: 24px; }
-    button:focus-visible, summary:focus-visible { outline: 1px solid var(--vscode-focusBorder); }
-    .label {
-        min-width: 140px;
-        color: var(--vscode-symbolIcon-fieldForeground);
-        white-space: nowrap;
-    }
-    body.vector .label {
-        min-width: 64px;
-    }
-    body.vector .item {
-        gap: 8px;
-    }
-    .str {
-        flex: 1;
-        color: var(--vscode-descriptionForeground);
-        white-space: pre-wrap;
-    }
-    button {
-        display: flex;
-        align-items: center;
-        border: 0;
-        padding: 2px;
-        color: var(--vscode-foreground);
-        background: transparent;
-        cursor: pointer;
-        font: inherit;
-    }
-    button:hover {
-        background-color: var(--vscode-toolbar-hoverBackground);
-    }
-    .load-more {
-        margin: 8px;
-    }
-    .load-more[hidden] {
-        display: none;
-    }
+    ${listViewerStyle}
     </style>
 </head>
-<body>
+<body class="r-list-viewer">
     <div class="navigation">
-        <button id="back" title="Back" aria-label="Back" disabled><span class="codicon codicon-arrow-left" aria-hidden="true"></span>Back</button>
-        <nav id="breadcrumbs" aria-label="Object path"></nav>
+        <button id="back" class="back" title="Back" aria-label="Back" disabled><span class="codicon codicon-arrow-left" aria-hidden="true"></span>Back</button>
+        <nav id="breadcrumbs" class="breadcrumbs" aria-label="Object path"></nav>
     </div>
-    <div id="navigation-status" role="status"></div>
-    <div id="list"></div>
+    <div id="navigation-status" class="navigation-status" role="status"></div>
+    <div id="list" class="list"></div>
     <script>
     ${getListViewerScript(documentGeneration, navigation ?? {
         title, path: [], breadcrumbs: [{ label: title, path: [] }],

From ba4166c442369dad387fed6d6d3934561f385b68 Mon Sep 17 00:00:00 2001
From: Kun Ren <renkun@outlook.com>
Date: Tue, 6 Oct 2026 22:54:54 +0800
Subject: [PATCH 2/5] feat(interactive): show unclassed lists with viewer and
 text controls

---
 sess/R/interactive.R                      | 10 ++++
 src/interactive/manager.ts                | 36 ++++++++++++--
 src/interactive/renderer.ts               | 57 +++++++++++++++++++++--
 src/interactive/rendererToolbar.ts        |  1 +
 src/test/browser/interactiveRenderer.html | 45 ++++++++++++++++++
 src/test/node/interactiveRuntime.test.ts  | 28 +++++++++++
 src/test/suite/interactiveEditor.test.ts  | 47 ++++++++++++++++++-
 7 files changed, 213 insertions(+), 11 deletions(-)

diff --git a/sess/R/interactive.R b/sess/R/interactive.R
index b6c1ce5af..f5ac6358a 100644
--- a/sess/R/interactive.R
+++ b/sess/R/interactive.R
@@ -401,6 +401,16 @@ interactive_execute <- function(id, code, source = NULL) {
                                     printed))
     return(TRUE)
   }
+  if (is.list(value) && !is.object(value)) {
+    view_id <- dataview_new_id()
+    root <- listview_state(value, "List", "List")
+    dataview_set_state(view_id, root)
+    preview <- get_workspace_children(view_id = view_id)
+    .interactive_event("display", c(list(kind = "list", viewId = view_id,
+                                         navigation = listview_navigation(listview_location(root))),
+                                    preview, .interactive_table_text(value)))
+    return(TRUE)
+  }
   if (inherits(value, "htmlwidget") && requireNamespace("htmlwidgets", quietly = TRUE)) {
     directory <- tempfile("widget-")
     dir.create(directory)
diff --git a/src/interactive/manager.ts b/src/interactive/manager.ts
index ba95239c5..1f204b350 100644
--- a/src/interactive/manager.ts
+++ b/src/interactive/manager.ts
@@ -68,7 +68,7 @@ export class InteractiveManager implements vscode.Disposable, vscode.TreeDataPro
     private closed = false;
     private clientId: string;
     private savedConnections: Map<string, SavedConnection>;
-    private outputViews: Map<string, { tableView?: string; selectedPlot?: string }>;
+    private outputViews: Map<string, { tableView?: string; listView?: string; selectedPlot?: string }>;
     private status = vscode.window.createStatusBarItem(vscode.StatusBarAlignment.Left, 20);
 
     constructor(private context: vscode.ExtensionContext) {
@@ -1064,6 +1064,7 @@ export class InteractiveManager implements vscode.Disposable, vscode.TreeDataPro
                     archived: cell.generation !== view.model.generation, connected: view.client.connected,
                     running: !['exited', 'stopping'].includes(view.client.manifest.status) };
                 const preference = this.outputViews.get(`${view.client.manifest.id}:${cell.generation}:${String(data.displayId)}`);
+                if (data.kind === 'list') { display.listView = preference?.listView ?? 'list'; }
                 if (data.kind === 'table') { display.tableView = preference?.tableView ?? util.config().get('interactive.tableView', 'table'); }
                 if (data.svg || data.asset) { display.url = view.base + String(data.svg ?? data.asset).split('/').map(encodeURIComponent).join('/'); }
                 else if (typeof data.url === 'string' && /^https?:\/\/(localhost|127\.0\.0\.1)(:|\/)/.test(data.url)) {
@@ -1071,7 +1072,7 @@ export class InteractiveManager implements vscode.Disposable, vscode.TreeDataPro
                 }
                 if (data.kind === 'mime' && data.mime === 'text/html') { display.kind = 'htmlText'; }
                 items = [vscode.NotebookCellOutputItem.json(display, DISPLAY_MIME),
-                    vscode.NotebookCellOutputItem.text(data.kind === 'table' ? (typeof data.printedText === 'string' ? data.printedText : `${String(data.totalRows)} rows\n${JSON.stringify(data.rows, null, 2)}`) : `R ${String(data.kind)} output`)];
+                    vscode.NotebookCellOutputItem.text(typeof data.printedText === 'string' ? data.printedText : data.kind === 'table' ? `${String(data.totalRows)} rows\n${JSON.stringify(data.rows, null, 2)}` : data.kind === 'list' ? JSON.stringify(data.children, null, 2) : `R ${String(data.kind)} output`)];
                 if (typeof data.svg === 'string') {
                     try {
                         const svg = portable ? readAsset(path.join(this.root, view.client.manifest.id, 'assets'), data.svg).toString('base64')
@@ -1185,19 +1186,20 @@ export class InteractiveManager implements vscode.Disposable, vscode.TreeDataPro
         const data = output.data;
         try {
             if ((message.action === 'tableView' && data.kind === 'table' && ['table', 'text'].includes(String(message.mode))) ||
+                (message.action === 'listView' && data.kind === 'list' && ['list', 'text'].includes(String(message.mode))) ||
                 (message.action === 'plotPage' && ['plot', 'image'].includes(String(data.kind)) && owner?.outputs.some(item => item.type === 'display' &&
                     ['plot', 'image'].includes(String(item.data.kind)) && item.data.displayId === message.selectedPlot))) {
                 const key = `${view.client.manifest.id}:${owner.generation}:${String(data.displayId)}`;
-                const preference = message.action === 'tableView' ? { tableView: String(message.mode) } : { selectedPlot: String(message.selectedPlot) };
+                const preference = message.action === 'tableView' ? { tableView: String(message.mode) } : message.action === 'listView' ? { listView: String(message.mode) } : { selectedPlot: String(message.selectedPlot) };
                 this.outputViews.delete(key); this.outputViews.set(key, preference);
                 while (this.outputViews.size > 1000) { this.outputViews.delete(this.outputViews.keys().next().value as string); }
                 await this.context.workspaceState.update('r.interactive.outputViews', [...this.outputViews]);
                 return;
             }
-            if (['table', 'page', 'resize'].includes(String(message.action)) && ['exited', 'stopping'].includes(view.client.manifest.status)) {
+            if (['table', 'page', 'list', 'listPage', 'listNavigate', 'listItem', 'resize'].includes(String(message.action)) && ['exited', 'stopping'].includes(view.client.manifest.status)) {
                 throw new Error('R has stopped. Start a new session and run the code again to use live controls.');
             }
-            if (['table', 'page', 'resize'].includes(String(message.action)) && (view.restarting || owner?.generation !== view.model.generation)) {
+            if (['table', 'page', 'list', 'listPage', 'listNavigate', 'listItem', 'resize'].includes(String(message.action)) && (view.restarting || owner?.generation !== view.model.generation)) {
                 throw new Error('This output belongs to a previous R process. Run its code again to use live controls.');
             }
             let result: unknown;
@@ -1209,6 +1211,28 @@ export class InteractiveManager implements vscode.Disposable, vscode.TreeDataPro
                     if (data.kind !== 'table') { return; }
                     result = await queryTablePage(data, message, request => view.client.request('inspect', request)); break;
                 }
+                case 'list': case 'listPage': case 'listNavigate': case 'listItem': {
+                    if (data.kind !== 'list') { return; }
+                    const listPath = message.path ?? [];
+                    if (!Array.isArray(listPath) || !listPath.every(index => Number.isSafeInteger(index) && index > 0)) { throw new Error('Invalid list path'); }
+                    const params = { view_id: data.viewId, path: listPath };
+                    if (message.action === 'listPage') {
+                        if (!Number.isSafeInteger(message.start) || Number(message.start) < 1) { throw new Error('Invalid list page'); }
+                        result = await view.client.request('inspect', { method: 'workspace_children', params: { ...params, start: message.start } });
+                    } else {
+                        if (message.action === 'listItem' && (!Number.isSafeInteger(message.index) || Number(message.index) < 1)) { throw new Error('Invalid list index'); }
+                        const navigation = await view.client.request<ListViewNavigation | boolean>('inspect', {
+                            method: message.action === 'listItem' ? 'listview_view' : 'listview_navigate', params: { ...params, index: message.index },
+                        });
+                        if (!navigation) { throw new Error('Unable to open this item. Check the R session and try again.'); }
+                        if (typeof navigation === 'object' && Array.isArray(navigation.breadcrumbs)) {
+                            if (message.action === 'list') {
+                                await session.showDataView('list', 'json', `${view.client.manifest.label}: ${navigation.title}`, '', 'Beside', String(data.viewId), navigation, view.target.sessionId);
+                            } else { result = { navigation }; }
+                        }
+                    }
+                    break;
+                }
                 case 'resize':
                     if (data.kind !== 'plot') { return; }
                     await view.client.request('resize', { device: data.device, plot: data.plot, width: message.width, height: message.height }); break;
@@ -1534,6 +1558,8 @@ export class InteractiveManager implements vscode.Disposable, vscode.TreeDataPro
                         const columns = data.columns as { field: string; headerName: string; type?: unknown }[];
                         const rows = data.rows as Record<string, unknown>[];
                         sections.push(`<table><tr>${columns.map(column => `<th style="text-align:${tableColumnAlignment(data, column)}">${escapeXml(column.headerName)}</th>`).join('')}</tr>${rows.map((row, rowIndex) => `<tr>${columns.map(column => `<td style="text-align:${tableColumnAlignment(data, column)}">${escapeXml(tableDisplayValue(data, row, column.field, rowIndex))}</td>`).join('')}</tr>`).join('')}</table><p>${tableSnapshotSummary(data) || `${String(data.totalRows)} rows (preview)`}</p>`);
+                    } else if (data.kind === 'list') {
+                        sections.push(`<pre>${escapeXml(data.printedText ?? JSON.stringify(data.children, null, 2))}</pre>`);
                     } else if (data.kind === 'mime' && data.mime === 'text/html') {
                         sections.push(`<iframe sandbox="allow-scripts" srcdoc="${escapeXml(String(data.text))}" style="width:100%;height:500px;border:0"></iframe>`);
                     } else { sections.push(`<pre>${escapeXml(data.text ?? data.message ?? JSON.stringify(data, null, 2))}</pre>`); }
diff --git a/src/interactive/renderer.ts b/src/interactive/renderer.ts
index 6ff7e6e5e..2721de718 100644
--- a/src/interactive/renderer.ts
+++ b/src/interactive/renderer.ts
@@ -1,6 +1,7 @@
 /// <reference lib="dom" />
 
 import { createInlineTable, InlineTable, InlineTableState, inlineTableStyle } from './inlineTable';
+import { createListViewer, ListViewer, ListViewNavigation, ListViewPage, ListViewReply, listViewerStyle } from '../listViewer';
 import { toolbarButton as button, toolbarStyle } from './rendererToolbar';
 
 interface OutputItem { id: string; json(): Record<string, unknown> }
@@ -12,7 +13,7 @@ interface RendererContext {
 export function activate(context: RendererContext): { renderOutputItem(item: OutputItem, element: HTMLElement): void; disposeOutputItem(id?: string): void } {
     interface OutputState {
         element: HTMLElement; data: Record<string, unknown>;
-        table?: InlineTable;
+        table?: InlineTable; list?: ListViewer;
         saveRequest?: number; saveButton?: HTMLButtonElement; savePlot?(format: string): void; updatePlotPaging?(): void;
         dispose?(): void;
     }
@@ -20,8 +21,8 @@ export function activate(context: RendererContext): { renderOutputItem(item: Out
     const tables = new Map<string, InlineTableState>();
     // Output IDs change on replaceOutput. Keep local choices until the host has
     // persisted them, and while browsing a saved notebook without a live host.
-    const choices = new Map<string, { tableView?: string; selectedPlot?: string }>();
-    const remember = (key: string, value: { tableView?: string; selectedPlot?: string }): void => {
+    const choices = new Map<string, { tableView?: string; listView?: string; selectedPlot?: string }>();
+    const remember = (key: string, value: { tableView?: string; listView?: string; selectedPlot?: string }): void => {
         choices.delete(key); choices.set(key, value);
         while (choices.size > 1000) { choices.delete(choices.keys().next().value as string); }
     };
@@ -38,6 +39,8 @@ export function activate(context: RendererContext): { renderOutputItem(item: Out
         const status = output.element.querySelector('[data-status]');
         if (message.action === 'page') {
             output.table?.reply(message);
+        } else if (['listPage', 'listNavigate', 'listItem'].includes(String(message.action))) {
+            output.list?.reply({ ...message.result as ListViewReply, requestId: Number(message.requestId), error: typeof message.error === 'string' ? message.error : undefined });
         } else if (message.action === 'saveAs') {
             if (message.requestId !== output.saveRequest || output.saveRequest === undefined) { return; }
             output.saveRequest = undefined;
@@ -63,7 +66,14 @@ export function activate(context: RendererContext): { renderOutputItem(item: Out
             element.classList.add('r-interactive-output');
             element.style.cssText = 'color:var(--vscode-editor-foreground);font-family:var(--vscode-font-family)';
             const style = document.createElement('style');
-            style.textContent = toolbarStyle + inlineTableStyle;
+            style.textContent = toolbarStyle + inlineTableStyle + listViewerStyle + `
+.r-interactive-output .r-list-viewer .arrow{display:inline-block;width:8px;height:8px;margin:4px}
+.r-interactive-output .r-list-viewer .codicon-chevron-right{display:inline-block;width:6px;height:6px;border-top:1px solid currentColor;border-right:1px solid currentColor;transform:rotate(45deg);margin:4px}
+.r-interactive-output .r-list-viewer details[open] > summary > .arrow{transform:rotate(135deg)}
+.r-interactive-output .r-list-viewer .codicon-open-preview::before{content:'↗'}
+.r-interactive-output .r-list-viewer .str{overflow-wrap:anywhere;min-width:0}
+.r-interactive-output .r-list-viewer .label{min-width:64px}
+`;
             element.append(style);
             const state: OutputState = { element, data: { ...data } }; outputs.set(item.id, state);
             const toolbar = document.createElement('div'); toolbar.className = 'r-interactive-toolbar';
@@ -104,6 +114,43 @@ export function activate(context: RendererContext): { renderOutputItem(item: Out
                 }, 'Text');
                 toolbar.prepend(open, toggle); showView();
                 state.dispose = () => { state.table?.dispose(); open.onclick = null; toggle.onclick = null; };
+            } else if (data.kind === 'list') {
+                const tree = document.createElement('div'); tree.className = 'r-list-viewer'; tree.dataset.list = '';
+                tree.style.cssText = 'display:flex;flex-direction:column;max-height:460px;overflow:hidden';
+                const navigation = document.createElement('div'); navigation.className = 'navigation';
+                const back = button('Back', 'previous', () => undefined); back.classList.add('back');
+                const breadcrumbs = document.createElement('nav'); breadcrumbs.className = 'breadcrumbs';
+                breadcrumbs.setAttribute('aria-label', 'Object path'); navigation.append(back, breadcrumbs);
+                const navigationStatus = document.createElement('div'); navigationStatus.className = 'navigation-status';
+                navigationStatus.setAttribute('role', 'status');
+                const list = document.createElement('div'); list.className = 'list';
+                tree.append(navigation, navigationStatus, list); element.append(tree);
+                const initial = data.navigation as ListViewNavigation ?? { title: 'List', path: [], breadcrumbs: [{ label: 'List', path: [] }] };
+                state.list = createListViewer({ root: tree, list, back, breadcrumbs, navigationStatus }, initial, message => {
+                    const id = ++requestId;
+                    const action = message.message === 'listview/page' ? 'listPage' : message.message === 'listview/navigate' ? 'listNavigate' : 'listItem';
+                    send(item, data, action, { path: message.path, index: message.index, start: message.start, requestId: id }); return id;
+                }, Array.isArray(data.children) ? data as unknown as ListViewPage : undefined, live);
+                const printed = document.createElement('pre'); printed.dataset.printed = '';
+                printed.style.cssText = 'white-space:pre;overflow:auto;max-height:460px;font-family:var(--vscode-editor-font-family,monospace);font-size:var(--vscode-editor-font-size,12px)';
+                printed.textContent = typeof data.printedText === 'string' ? data.printedText : ''; element.append(printed);
+                const open = button('Open list viewer', 'list', () => send(item, data, 'list', { path: state.list?.navigation().path }), 'List viewer');
+                open.disabled = !live;
+                const hasText = typeof data.printedText === 'string';
+                let text = hasText && (choice?.listView ?? data.listView) === 'text';
+                const showView = (): void => {
+                    tree.hidden = text; printed.hidden = !text;
+                    toggle.replaceChildren(...Array.from(button('', text ? 'list' : 'text', () => undefined, text ? 'List' : 'Text').childNodes));
+                    toggle.title = text ? 'Show list preview' : 'Show R printed output'; toggle.setAttribute('aria-label', toggle.title);
+                    toggle.disabled = !hasText;
+                    if (!hasText) { toggle.title = data.printError ? `R printout unavailable: ${typeof data.printError === 'string' ? data.printError : JSON.stringify(data.printError)}` : 'Printed output unavailable'; }
+                };
+                const toggle = button('Show R printed output', 'text', () => {
+                    text = !text; remember(choiceKey, { listView: text ? 'text' : 'list' });
+                    send(item, data, 'listView', { mode: text ? 'text' : 'list' }); showView();
+                }, 'Text');
+                toolbar.append(open, toggle); status.textContent = connectionHint(data); showView();
+                state.dispose = () => { state.list?.dispose(); open.onclick = null; toggle.onclick = null; };
             } else if (data.kind === 'plot') {
                 const pages = (Array.isArray(data.pages) && data.pages.length ? data.pages : [data]) as Record<string, unknown>[];
                 const selected = choice?.selectedPlot ?? data.selectedPlot;
@@ -195,7 +242,7 @@ export function activate(context: RendererContext): { renderOutputItem(item: Out
             toolbar.append(status);
             if (!toolbar.parentElement) { element.append(toolbar); }
 
-            if (data.kind !== 'table') {
+            if (!['table', 'list'].includes(String(data.kind))) {
                 status.textContent = [status.textContent, connectionHint(data)].filter(Boolean).join(' · ');
                 if (!connected && data.kind !== 'plot') { toolbar.querySelectorAll('button').forEach(control => { control.disabled = true; }); }
             }
diff --git a/src/interactive/rendererToolbar.ts b/src/interactive/rendererToolbar.ts
index f069fe42f..4ecf32d76 100644
--- a/src/interactive/rendererToolbar.ts
+++ b/src/interactive/rendererToolbar.ts
@@ -8,6 +8,7 @@ const paths = {
     reset: 'M3 6a5 5 0 1 1 0 5M3 2v4h4',
     filter: 'M2 3h12L9 8v5l-2 1V8Z',
     table: 'M2 2h12v12H2ZM2 6h12M6 2v12',
+    list: 'M2 3h1M6 3h8M2 8h1M6 8h8M2 13h1M6 13h8',
     text: 'M2 3h12M2 6h9M2 9h12M2 12h9',
     open: 'M9 2h5v5M14 2 7 9M6 3H2v11h11v-4',
     save: 'M8 2v8M4 6l4 4 4-4M2 10v4h12v-4',
diff --git a/src/test/browser/interactiveRenderer.html b/src/test/browser/interactiveRenderer.html
index da3dd2a1a..63c85df3c 100644
--- a/src/test/browser/interactiveRenderer.html
+++ b/src/test/browser/interactiveRenderer.html
@@ -17,6 +17,7 @@ <h1>R Interactive output</h1>
 <section><h2>Numeric precision</h2><div id="numeric"></div></section>
 <section><h2>Large dataset preview</h2><div id="large"></div></section>
 <section><h2>Data preview</h2><div id="table"></div></section>
+<section><h2>List preview</h2><div id="list"></div></section>
 <section><h2>Plot export</h2><div id="plot"></div></section>
 <section><h2>Saved table</h2><div id="offline"></div></section>
 <section><h2>Saved plot</h2><div id="offline-plot"></div></section>
@@ -47,6 +48,49 @@ <h1>R Interactive output</h1>
  img.addEventListener('error',()=>{ clearTimeout(timeout); reject(new Error('Plot load failed')); },{ once:true });
 });
 try {
+ const listHost = document.querySelector('#list');
+ const listData = {kind:'list',displayId:'list',generation:'r1',navigation:{title:'List',path:[],breadcrumbs:[{label:'List',path:[]}]},
+   children:[{label:'$ nested',str:'List of 1',index:1,viewable:true,has_children:true},{label:'[[2]]',str:'chr "<tag> λ"',index:2,viewable:true}],next_start:501,
+   printedText:'$nested\n$nested$value\n[1] 1 2\n\n[[2]]\n[1] "<tag> λ"\n'};
+ render('list',listData,listHost);
+ check(listHost.querySelectorAll('.item').length===2 && listHost.querySelector('.str').textContent==='List of 1','List preview must use saved rows');
+ check(control(listHost,'Open list viewer').textContent.includes('List viewer'),'List viewer action must be below the tree');
+ const nested = listHost.querySelector('details'); nested.open=true;
+ await new Promise(resolve=>setTimeout(resolve,0));
+ const expansion = messages.at(-1);
+ check(expansion.action==='listPage' && expansion.path.join(',')==='1','List expansion must load only the selected branch');
+ reply(expansion,{result:{children:[{label:'$ value',str:'num [1:2] 1 ...',index:1,viewable:true}],next_start:null}});
+ check(nested.querySelector('.children .item').textContent.includes('$ value'),'Expanded rows must render the live response');
+ control(listHost,'View $ nested').click(); const navigate=messages.at(-1);
+ check(navigate.action==='listItem' && navigate.index===1,'View must navigate the retained root');
+ reply(navigate,{result:{navigation:{title:'List$nested',path:[1],breadcrumbs:[{label:'List',path:[]},{label:'nested',path:[1]}]}}});
+ reply(messages.at(-1),{result:{children:[{label:'$ value',str:'num [1:2] 1 ...',index:1}],next_start:null}});
+ control(listHost,'Back').click(); const backRequest=messages.at(-1);
+ reply(backRequest,{result:{navigation:listData.navigation}});
+ check(listHost.querySelector('details')===nested && nested.open,'Back must retain expanded list rows');
+ listHost.querySelector('.list > div > .load-more').click(); const more=messages.at(-1);
+ check(more.action==='listPage' && more.start===501,'Load more must request the next list page');
+ reply(more,{error:'Temporary failure'});
+ check(listHost.querySelector('.list > div > .load-more').textContent==='Retry','List pages must offer retry after errors');
+ listHost.querySelector('.list > div > .load-more').click(); reply(messages.at(-1),{result:{children:[],next_start:null}});
+ control(listHost,'Open list viewer').click();
+ check(messages.at(-1).action==='list' && messages.at(-1).path.length===0,'Expanded viewer must open the current path');
+ control(listHost,'Show R printed output').click();
+ check(listHost.querySelector('[data-list]').hidden && listHost.querySelector('[data-printed]').textContent===listData.printedText,'List Text must preserve exact R printing');
+ render('list-replaced',{...listData,connected:false},listHost);
+ check(!listHost.querySelector('[data-printed]').hidden && control(listHost,'Open list viewer').disabled,'List choices must survive replacement and offline controls must disable');
+ control(listHost,'Show list preview').click();
+ check(!listHost.querySelector('[data-list]').hidden && listHost.querySelectorAll('.item').length===2,'Saved lists must allow local preview switching');
+ const offlineCount=messages.length;
+ listHost.querySelector('details').open=true; await new Promise(resolve=>setTimeout(resolve,0));
+ check(messages.length===offlineCount && !listHost.querySelector('details').open,'Offline expansion must avoid live requests');
+ render('list-archived',{...listData,archived:true},listHost);
+ control(listHost,'Show R printed output').click();
+ check(!listHost.querySelector('[data-printed]').hidden && control(listHost,'Open list viewer').disabled,'Archived list text must remain available');
+ render('list-stopped',{...listData,running:false},listHost);
+ control(listHost,'Show list preview').click();
+ check(!listHost.querySelector('[data-list]').hidden && control(listHost,'Open list viewer').disabled,'Stopped lists must retain saved previews');
+ render('list',listData,listHost);
  const numeric = document.querySelector('#numeric');
  const numericData = { kind:'table', columns:[{ field:'0',headerName:'Row' },{ field:'1',headerName:'price_per_carat' },{ field:'2',headerName:'Integer64 ID',type:'bigintColumn' }],
    rows:[{ '0':1,'1':326/0.23,'2':'9007199254740993' },{ '0':2,'1':326/0.21,'2':'9007199254740994' },{ '0':3,'1':1400,'2':'9007199254740995' }],
@@ -304,6 +348,7 @@ <h1>R Interactive output</h1>
  renderer.disposeOutputItem();
  // Restore usable examples for manual pointer, Tab/Shift+Tab, and visual checks.
  render('plot',galleryData,plot);
+ render('list',listData,listHost);
  render('table',printedData,table);
  render('large-demo',{ ...largeData,displayId:'large-demo',totalRows:1000 },document.querySelector('#large'));
  document.querySelector('#result').scrollIntoView();
diff --git a/src/test/node/interactiveRuntime.test.ts b/src/test/node/interactiveRuntime.test.ts
index aa9e30e58..7deb999dc 100644
--- a/src/test/node/interactiveRuntime.test.ts
+++ b/src/test/node/interactiveRuntime.test.ts
@@ -290,6 +290,34 @@ stopifnot(identical(actual, expected))`);
         assert.strictEqual((await finished(current)).state, 'success');
     });
 
+    test('unclassed lists retain printable previews and lazy pages across reconnects', async () => {
+        const id = await submit('x <- list(nested=list(value=c(1,2)), table=data.frame(id=1:2), "λ <tag>"); x');
+        assert.strictEqual((await finished(id)).state, 'success');
+        const output = events.find(event => event.executionId === id && event.data.kind === 'list'); assert.ok(output);
+        const children = output.data.children as { label: string; has_children: boolean }[];
+        assert.deepStrictEqual(children.map(child => child.label), ['$ nested', '$ table', '[[3]]']);
+        assert.strictEqual(children[0].has_children, true);
+        assert.match(String(output.data.printedText), /\$nested\$value/);
+        assert.ok(!text(id).includes('$nested'), 'The rich list replaces automatic console printing');
+        const expected = await submit('print(x)'); await finished(expected);
+        assert.strictEqual(output.data.printedText, text(expected));
+        await finished(await submit('x$nested$value <- 99; invisible(NULL)'));
+        const page = await client.request<{ children: { str: string }[] }>('inspect', { method: 'workspace_children', params: {
+            view_id: output.data.viewId, path: [1], start: 1,
+        } });
+        assert.match(page.children[0].str, /1/); assert.ok(!page.children[0].str.includes('99'));
+        const explicit = await submit('sess::display(list()); View(list(a=1)); structure(list(a=2), class="custom_list")');
+        assert.strictEqual((await finished(explicit)).state, 'success');
+        assert.strictEqual(events.filter(event => event.executionId === explicit && event.data.kind === 'list').length, 2);
+        assert.match(text(explicit), /custom_list/);
+        const large = await submit('as.list(seq_len(501))'); await finished(large);
+        const largeList = events.find(event => event.executionId === large && event.data.kind === 'list'); assert.ok(largeList);
+        assert.strictEqual((largeList.data.children as unknown[]).length, 500);
+        assert.strictEqual(largeList.data.next_start, 501);
+        client.close(); await client.connect(); await client.subscribe(0);
+        assert.deepStrictEqual((await client.snapshot()).events.find(event => event.seq === output.seq)?.data, output.data);
+    });
+
     test('huge tables keep bounded snapshots and page the full data without materializing it', async () => {
         const id = await submit(`n <- 832976871L
 huge <- structure(rep(list(seq_len(n)), 23L), names=paste0("x", 1:23),
diff --git a/src/test/suite/interactiveEditor.test.ts b/src/test/suite/interactiveEditor.test.ts
index 52b0f1273..e0fece9d3 100644
--- a/src/test/suite/interactiveEditor.test.ts
+++ b/src/test/suite/interactiveEditor.test.ts
@@ -1191,6 +1191,51 @@ cat("\n")`;
             sinon.assert.notCalled(errors);
         } finally { errors.restore(); saved.restore(); format.restore(); }
     });
+    test('unclassed list cells route browsing to their owner and save text preferences', async () => {
+        await vscode.commands.executeCommand('r.interactive.open', manifests[0]);
+        const notebook = vscode.workspace.notebookDocuments.find(doc => doc.metadata.rSessionId === manifests[0].id); assert.ok(notebook);
+        const index = notebook.cellCount;
+        await vscode.commands.executeCommand('r.runSelection', 'list(nested=list(value=1:2), table=data.frame(value=1:2))');
+        await until(() => notebook.cellCount > index && notebook.cellAt(index).executionSummary?.success === true);
+        const custom = notebook.cellAt(index).outputs.flatMap(output => output.items).find(item => item.mime === DISPLAY_MIME); assert.ok(custom);
+        const list = JSON.parse(Buffer.from(custom.data).toString()) as Record<string, unknown>;
+        assert.strictEqual(list.kind, 'list'); assert.strictEqual((list.children as unknown[]).length, 2);
+        const plain = notebook.cellAt(index).outputs.flatMap(output => output.items).find(item => item.mime === 'text/plain'); assert.ok(plain);
+        assert.strictEqual(Buffer.from(plain.data).toString(), list.printedText);
+        const context = bundleContext();
+        const manager = context.subscriptions.find(item => typeof (item as InteractiveManager).open === 'function') as unknown as {
+            messages: vscode.NotebookRendererMessaging;
+            rendererMessage(editor: vscode.NotebookEditor, message: Record<string, unknown>): Promise<void>;
+        };
+        const editor = vscode.window.visibleNotebookEditors.find(editor => editor.notebook === notebook); assert.ok(editor);
+        const replies = sinon.spy(manager.messages, 'postMessage');
+        const panels = sinon.spy(vscode.window, 'createWebviewPanel');
+        const saved = sinon.stub(vscode.window, 'showSaveDialog').resolves(vscode.Uri.file(path.join(root, 'list.rnb')));
+        const format = sinon.stub(vscode.window, 'showQuickPick').resolves({label:'Notebook',format:'rnb'} as vscode.QuickPickItem);
+        const message = {displayId:list.displayId,generation:list.generation,outputId:'list-test'};
+        try {
+            await vscode.commands.executeCommand('r.interactive.open', manifests[1]);
+            await manager.rendererMessage(editor, {...message,action:'listPage',path:[1],start:1,requestId:1});
+            const page = replies.lastCall.args[0] as {result:{children:{label:string}[]}};
+            assert.strictEqual(page.result.children[0].label, '$ value');
+            await manager.rendererMessage(editor, {...message,action:'listItem',path:[],index:2,requestId:2});
+            await until(() => panels.calledOnce); assert.strictEqual(panels.firstCall.args[1], 'List$table');
+            await manager.rendererMessage(editor, {...message,action:'list',path:[]});
+            assert.strictEqual(panels.callCount, 2);
+            assert.strictEqual(notebook.cellCount, index+1, 'Browsing must not run another cell');
+            await manager.rendererMessage(editor, {...message,action:'listView',mode:'text'});
+            await vscode.commands.executeCommand('r.interactive.export', notebook.uri);
+            const report = new InteractiveSerializer().deserializeNotebook(fs.readFileSync(path.join(root,'list.rnb')));
+            const item = report.cells.at(-1)?.outputs?.flatMap(output=>output.items).find(item=>item.mime===DISPLAY_MIME); assert.ok(item);
+            const exported = JSON.parse(Buffer.from(item.data).toString()) as Record<string,unknown>;
+            assert.strictEqual(exported.listView,'text'); assert.strictEqual(exported.connected,false);
+            assert.strictEqual(exported.printedText,list.printedText);
+        } finally {
+            replies.restore();
+            panels.returnValues.forEach(panel => { panel.dispose(); }); panels.restore(); saved.restore(); format.restore();
+        }
+    });
+
     test('Interactive list viewers open nested tables in their original session', async () => {
         await vscode.commands.executeCommand('r.interactive.open', manifests[0]);
         const original = vscode.window.createWebviewPanel;
@@ -1203,7 +1248,7 @@ cat("\n")`;
             return panel;
         });
         try {
-            await vscode.commands.executeCommand('r.runSelection', 'rebase_view <- list(table=data.frame(value=1:2)); View(rebase_view)');
+            await vscode.commands.executeCommand('r.runSelection', 'rebase_view <- structure(list(table=data.frame(value=1:2)), class="test_list"); View(rebase_view)');
             await until(() => panels.length === 1 && receivers[0].calledOnce);
             assert.strictEqual(panels[0].title, 'rebase_view');
             await vscode.commands.executeCommand('r.interactive.open', manifests[1]);

From 531a40e317685e1238e63933680410124da32321 Mon Sep 17 00:00:00 2001
From: Kun Ren <renkun@outlook.com>
Date: Tue, 6 Oct 2026 23:03:48 +0800
Subject: [PATCH 3/5] feat(viewer): reset list navigation to the initial view

---
 src/interactive/renderer.ts               |  6 ++-
 src/listViewer.ts                         | 19 +++++---
 src/session.ts                            |  1 +
 src/test/browser/interactiveRenderer.html |  7 +++
 src/test/suite/listViewer.test.ts         | 59 ++++++++++++++++++++++-
 5 files changed, 82 insertions(+), 10 deletions(-)

diff --git a/src/interactive/renderer.ts b/src/interactive/renderer.ts
index 2721de718..3ef312bc3 100644
--- a/src/interactive/renderer.ts
+++ b/src/interactive/renderer.ts
@@ -124,9 +124,11 @@ export function activate(context: RendererContext): { renderOutputItem(item: Out
                 const navigationStatus = document.createElement('div'); navigationStatus.className = 'navigation-status';
                 navigationStatus.setAttribute('role', 'status');
                 const list = document.createElement('div'); list.className = 'list';
+                const reset = button('Reset list view', 'reset', () => undefined, 'Reset');
+                reset.title = 'Return to the initial list, collapse expanded rows, and clear navigation history';
                 tree.append(navigation, navigationStatus, list); element.append(tree);
                 const initial = data.navigation as ListViewNavigation ?? { title: 'List', path: [], breadcrumbs: [{ label: 'List', path: [] }] };
-                state.list = createListViewer({ root: tree, list, back, breadcrumbs, navigationStatus }, initial, message => {
+                state.list = createListViewer({ root: tree, list, back, reset, breadcrumbs, navigationStatus }, initial, message => {
                     const id = ++requestId;
                     const action = message.message === 'listview/page' ? 'listPage' : message.message === 'listview/navigate' ? 'listNavigate' : 'listItem';
                     send(item, data, action, { path: message.path, index: message.index, start: message.start, requestId: id }); return id;
@@ -149,7 +151,7 @@ export function activate(context: RendererContext): { renderOutputItem(item: Out
                     text = !text; remember(choiceKey, { listView: text ? 'text' : 'list' });
                     send(item, data, 'listView', { mode: text ? 'text' : 'list' }); showView();
                 }, 'Text');
-                toolbar.append(open, toggle); status.textContent = connectionHint(data); showView();
+                toolbar.append(open, toggle, reset); status.textContent = connectionHint(data); showView();
                 state.dispose = () => { state.list?.dispose(); open.onclick = null; toggle.onclick = null; };
             } else if (data.kind === 'plot') {
                 const pages = (Array.isArray(data.pages) && data.pages.length ? data.pages : [data]) as Record<string, unknown>[];
diff --git a/src/listViewer.ts b/src/listViewer.ts
index c450c0740..117d43735 100644
--- a/src/listViewer.ts
+++ b/src/listViewer.ts
@@ -25,8 +25,9 @@ export interface ListViewer {
 
 /** Shared tree, paging and navigation for the panel and Interactive cells. */
 export function createListViewer(
-    { root, list, back, breadcrumbs, navigationStatus }: {
-        root: HTMLElement; list: HTMLElement; back: HTMLButtonElement; breadcrumbs: HTMLElement; navigationStatus: HTMLElement;
+    { root, list, back, reset, breadcrumbs, navigationStatus }: {
+        root: HTMLElement; list: HTMLElement; back: HTMLButtonElement; reset: HTMLButtonElement;
+        breadcrumbs: HTMLElement; navigationStatus: HTMLElement;
     },
     initial: ListViewNavigation,
     request: (message: { message: string; path: number[]; index?: number; start?: number }) => number,
@@ -36,7 +37,7 @@ export function createListViewer(
     const pending = new Map<number, (message: ListViewReply) => void>();
     const pages = new Map<string, { element: HTMLElement; scrollTop: number; loader: { loadOnce(): void } }>();
     const history: ListViewNavigation[] = [];
-    let current: ListViewNavigation;
+    let current: ListViewNavigation | undefined;
     let navigating = false;
     let disposed = false;
     function showNavigation(navigation: ListViewNavigation, goingBack = false): void {
@@ -57,6 +58,7 @@ export function createListViewer(
         list.replaceChildren(page.element);
         list.scrollTop = page.scrollTop;
         back.disabled = !live || history.length === 0;
+        reset.disabled = !live;
         breadcrumbs.replaceChildren();
         navigation.breadcrumbs.forEach((crumb, index) => {
             if (index) {
@@ -80,7 +82,7 @@ export function createListViewer(
         page.loader.loadOnce();
     }
 
-    function navigate(message: string, params: { path: number[]; index?: number }, goingBack = false): void {
+    function navigate(message: string, params: { path: number[]; index?: number }, goingBack = false, resetting = false): void {
         if (disposed || !live || navigating) { return; }
         navigating = true;
         navigationStatus.textContent = '';
@@ -90,6 +92,9 @@ export function createListViewer(
             if (response.error) {
                 navigationStatus.textContent = response.error;
             } else if (response.navigation) {
+                if (resetting) {
+                    pending.clear(); pages.clear(); history.length = 0; current = undefined;
+                }
                 showNavigation(response.navigation, goingBack);
             }
         });
@@ -98,6 +103,7 @@ export function createListViewer(
     back.addEventListener('click', () => {
         if (history.length) { navigate('listview/navigate', { path: history[history.length - 1].path }, true); }
     });
+    reset.addEventListener('click', () => navigate('listview/navigate', { path: initial.path }, false, true));
 
     function createPage(container: HTMLElement, path: number[], vector = false, savedPage?: ListViewPage): { loadOnce(): void } {
         const rows = document.createElement('div');
@@ -197,7 +203,7 @@ export function createListViewer(
 
     showNavigation(initial);
     return {
-        navigation: () => current,
+        navigation: () => current!,
         reply(message) {
             const receive = pending.get(message.requestId);
             if (receive) { pending.delete(message.requestId); receive(message); }
@@ -215,7 +221,7 @@ export function getListViewerScript(documentGeneration: number, initial: ListVie
     const documentGeneration = ${documentGeneration};
     let nextRequestId = 0;
     const viewer = (${createListViewer.toString()})({
-        root: document.body, list: document.getElementById('list'), back: document.getElementById('back'),
+        root: document.body, list: document.getElementById('list'), back: document.getElementById('back'), reset: document.getElementById('reset'),
         breadcrumbs: document.getElementById('breadcrumbs'), navigationStatus: document.getElementById('navigation-status'),
     }, ${JSON.stringify(initial).replace(/</g, '\\u003c')}, message => {
         const requestId = ++nextRequestId;
@@ -242,6 +248,7 @@ export const listViewerStyle = `
     }
     .r-list-viewer .back { gap: 4px; padding: 4px 6px; flex-shrink: 0; border-radius: 3px; }
     .r-list-viewer .back:disabled { opacity: 0.4; cursor: default; background: transparent; }
+    .r-list-viewer .reset { gap: 4px; padding: 4px 6px; flex-shrink: 0; border-radius: 3px; }
     .r-list-viewer .codicon { flex-shrink: 0; }
     .r-list-viewer .breadcrumbs {
         display: flex;
diff --git a/src/session.ts b/src/session.ts
index ba9061849..434db9551 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -1954,6 +1954,7 @@ export function getListHtml(
     <div class="navigation">
         <button id="back" class="back" title="Back" aria-label="Back" disabled><span class="codicon codicon-arrow-left" aria-hidden="true"></span>Back</button>
         <nav id="breadcrumbs" class="breadcrumbs" aria-label="Object path"></nav>
+        <button id="reset" class="reset" title="Reset to initial view" aria-label="Reset to initial view"><span class="codicon codicon-discard" aria-hidden="true"></span>Reset</button>
     </div>
     <div id="navigation-status" class="navigation-status" role="status"></div>
     <div id="list" class="list"></div>
diff --git a/src/test/browser/interactiveRenderer.html b/src/test/browser/interactiveRenderer.html
index 63c85df3c..f96f7ec13 100644
--- a/src/test/browser/interactiveRenderer.html
+++ b/src/test/browser/interactiveRenderer.html
@@ -75,9 +75,16 @@ <h1>R Interactive output</h1>
  listHost.querySelector('.list > div > .load-more').click(); reply(messages.at(-1),{result:{children:[],next_start:null}});
  control(listHost,'Open list viewer').click();
  check(messages.at(-1).action==='list' && messages.at(-1).path.length===0,'Expanded viewer must open the current path');
+ control(listHost,'View $ nested').click();
+ reply(messages.at(-1),{result:{navigation:{title:'List$nested',path:[1],breadcrumbs:[{label:'List',path:[]},{label:'nested',path:[1]}]}}});
+ control(listHost,'Reset list view').click(); const resetRequest=messages.at(-1);
+ check(resetRequest.action==='listNavigate' && resetRequest.path.length===0,'Reset must navigate directly to the initial list');
+ reply(resetRequest,{result:{navigation:listData.navigation}});
+ check(listHost.querySelectorAll('.item').length===2 && !listHost.querySelector('details').open && control(listHost,'Back').disabled,'Reset must restore saved rows, collapse the tree and clear history');
  control(listHost,'Show R printed output').click();
  check(listHost.querySelector('[data-list]').hidden && listHost.querySelector('[data-printed]').textContent===listData.printedText,'List Text must preserve exact R printing');
  render('list-replaced',{...listData,connected:false},listHost);
+ check(control(listHost,'Reset list view').disabled,'Offline reset must not query the session');
  check(!listHost.querySelector('[data-printed]').hidden && control(listHost,'Open list viewer').disabled,'List choices must survive replacement and offline controls must disable');
  control(listHost,'Show list preview').click();
  check(!listHost.querySelector('[data-list]').hidden && listHost.querySelectorAll('.item').length===2,'Saved lists must allow local preview switching');
diff --git a/src/test/suite/listViewer.test.ts b/src/test/suite/listViewer.test.ts
index 7d4f01f58..53be431dd 100644
--- a/src/test/suite/listViewer.test.ts
+++ b/src/test/suite/listViewer.test.ts
@@ -38,10 +38,11 @@ function createViewer(initial: ListViewNavigation = {
 }) {
     const root = new Element('div');
     const back = new Element('button');
+    const reset = new Element('button');
     const breadcrumbs = new Element('nav');
     const status = new Element('div');
     const bodyClasses = new Set<string>();
-    const elements: Record<string, Element> = { list: root, back, breadcrumbs, 'navigation-status': status };
+    const elements: Record<string, Element> = { list: root, back, reset, breadcrumbs, 'navigation-status': status };
     const messages: Request[] = [];
     let receive: (event: unknown) => void = () => undefined;
     vm.runInNewContext(getListViewerScript(7, initial), {
@@ -66,11 +67,65 @@ function createViewer(initial: ListViewNavigation = {
     });
     return {
         get root() { return root.children[0]; },
-        viewport: root, back, breadcrumbs, status, messages, reply, bodyClasses,
+        viewport: root, back, reset, breadcrumbs, status, messages, reply, bodyClasses,
     };
 }
 
 suite('List viewer', () => {
+    test('Reset restores the initial page, collapsed rows and scroll, and discards navigation and pending pages', () => {
+        const viewer = createViewer();
+        const initial = { title: 'x', path: [], breadcrumbs: [{ label: 'x', path: [] }] };
+        viewer.reply(viewer.messages[0], { children: [{ label: '$ a', index: 1, viewable: true, has_children: true }] });
+        const original = viewer.root;
+        const entry = original.children[0].children[0];
+        entry.open = true; entry.fire('toggle');
+        const expansion = viewer.messages[1];
+        viewer.viewport.scrollTop = 120;
+        const button = entry.children[0].children.at(-1); assert.ok(button);
+        button.fire('click', { preventDefault: () => undefined, stopPropagation: () => undefined });
+        viewer.reply(viewer.messages[2], { message: 'listview/navigation', navigation: {
+            title: 'x$a', path: [1], breadcrumbs: [{ label: 'x', path: [] }, { label: 'a', path: [1] }],
+        } });
+        const nestedPage = viewer.messages[3];
+        viewer.reset.fire('click');
+        assert.strictEqual(viewer.messages[4].message, 'listview/navigate');
+        assert.deepStrictEqual(viewer.messages[4].path, []);
+        viewer.reply(viewer.messages[4], { message: 'listview/navigation', navigation: initial });
+        assert.notStrictEqual(viewer.root, original);
+        assert.strictEqual(viewer.viewport.scrollTop, 0);
+        assert.strictEqual(viewer.back.disabled, true);
+        viewer.reply(expansion, { children: [{ label: 'stale' }] });
+        viewer.reply(nestedPage, { children: [{ label: 'stale' }] });
+        viewer.reply(viewer.messages[5], { children: [{ label: '$ a', index: 1, has_children: true }] });
+        assert.strictEqual(viewer.root.children[0].children[0].open, false);
+        assert.strictEqual(viewer.root.children[0].children[0].children[1].childElementCount, 0);
+        viewer.back.fire('click');
+        assert.strictEqual(viewer.messages.length, 6);
+    });
+
+    test('Reset returns to a deep initial path and a failed reset preserves the current page', () => {
+        const initial = { title: 'x$a', path: [1], breadcrumbs: [{ label: 'x', path: [] }, { label: 'a', path: [1] }] };
+        const viewer = createViewer(initial);
+        viewer.reply(viewer.messages[0], { children: [] });
+        viewer.breadcrumbs.children[0].fire('click');
+        viewer.reply(viewer.messages[1], { message: 'listview/navigation', navigation: {
+            title: 'x', path: [], breadcrumbs: [{ label: 'x', path: [] }],
+        } });
+        viewer.reply(viewer.messages[2], { children: [] });
+        const current = viewer.root;
+        viewer.reset.fire('click');
+        assert.deepStrictEqual(viewer.messages[3].path, [1]);
+        viewer.reply(viewer.messages[3], { message: 'listview/navigation', error: 'Unable to reset' });
+        assert.strictEqual(viewer.root, current);
+        assert.strictEqual(viewer.back.disabled, false);
+        assert.strictEqual(viewer.status.textContent, 'Unable to reset');
+        viewer.reset.fire('click');
+        viewer.reply(viewer.messages[4], { message: 'listview/navigation', navigation: initial });
+        assert.deepStrictEqual(viewer.messages[5].path, [1]);
+        assert.strictEqual(viewer.back.disabled, true);
+        assert.strictEqual(viewer.status.textContent, '');
+    });
+
     test('Back restores expanded rows, loaded pages and scroll without fetching them again', () => {
         const viewer = createViewer();
         const { messages, reply, back, viewport } = viewer;

From 61f13fbfa1ea4b5ff1baa68ce3f0748e2af174c2 Mon Sep 17 00:00:00 2001
From: Kun Ren <renkun@outlook.com>
Date: Tue, 6 Oct 2026 23:47:55 +0800
Subject: [PATCH 4/5] fix(list-viewer): show compact numeric vector previews

---
 sess/R/handlers.R                         | 13 ++++++++--
 sess/inst/tinytest/test-listview-format.R | 30 ++++++++++++++++++++---
 2 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/sess/R/handlers.R b/sess/R/handlers.R
index bc96216ed..ad0f10f50 100644
--- a/sess/R/handlers.R
+++ b/sess/R/handlers.R
@@ -374,8 +374,17 @@ listview_summary <- function(object) {
     } else if (size > 1L) {
       paste0(" [1:", size, "]")
     }
-    paste0(type, shape, " ",
-           listview_format_values(object[1L]), if (size > 1L) " ...")
+    numeric_preview <- is.numeric(object) && !is.object(object)
+    preview_size <- if (numeric_preview) min(size, 5L) else 1L
+    # Subset before formatting so even very large vectors have a bounded preview.
+    values <- object[seq_len(preview_size)]
+    formatted <- if (numeric_preview) {
+      vapply(values, format, "", digits = 3L, trim = TRUE, justify = "none")
+    } else {
+      listview_format_values(values)
+    }
+    paste0(type, shape, " ", paste(formatted, collapse = " "),
+           if (size > preview_size) " ...")
   } else {
     trimws(try_capture_str(object))
   }
diff --git a/sess/inst/tinytest/test-listview-format.R b/sess/inst/tinytest/test-listview-format.R
index 56f257c18..d3a888359 100644
--- a/sess/inst/tinytest/test-listview-format.R
+++ b/sess/inst/tinytest/test-listview-format.R
@@ -1,4 +1,4 @@
-# List rows use the same class formatting and numeric precision as table cells.
+# Individual vector rows retain table precision; numeric summaries are compact.
 local({
   runtime <- sess:::.sess_env
   previous <- runtime$dataviews
@@ -19,7 +19,9 @@ local({
                 "0", "NA", "NaN", "Inf", "-Inf")
   expect_equal(text(page(numbers)), expected)
   expect_equal(text(page(list(nested = numbers), list(1L))), expected)
-  expect_equal(text(page(as.list(numbers))), paste("num", expected))
+  compact <- c("1.23", "1.54e-100", "-6.65e-13", "1.23e+14",
+               "0", "NA", "NaN", "Inf", "-Inf")
+  expect_equal(text(page(as.list(numbers))), paste("num", compact))
   for (index in seq_along(numbers)) {
     expect_true(sess:::listview_supported(numbers[index]))
     expect_true(sess:::listview_is_vector(numbers[index]))
@@ -27,9 +29,29 @@ local({
     expect_false(page(numbers[index])$children[[1L]]$has_children)
     expect_false(page(numbers[index])$children[[1L]]$viewable)
   }
-  expect_true(grepl(expected[[1L]], text(page(list(numbers)))[[1L]], fixed = TRUE))
+  expect_equal(text(page(list(numbers))),
+               "num [1:9] 1.23 1.54e-100 -6.65e-13 1.23e+14 0 ...")
   expect_equal(text(page(list(matrix(rep(numbers[[1L]], 4L), nrow = 2L)))),
-               paste0("num [1:2, 1:2] ", expected[[1L]], " ..."))
+               "num [1:2, 1:2] 1.23 1.23 1.23 1.23")
+  values <- c(-1.33067613368562, -0.0827652250416069, 0.836484327361507,
+              1.23456789, -2.3456789)
+  root <- list(a = 1, b = rep(values, 2L), c = list(x = values, y = list(z = values[1:3])),
+               mtcars = datasets::mtcars)
+  expect_equal(text(page(root))[1:3],
+               c("num 1", "num [1:10] -1.33 -0.0828 0.836 1.23 -2.35 ...", "List of 2"))
+  expect_equal(text(page(root, list(3L)))[[1L]],
+               "num [1:5] -1.33 -0.0828 0.836 1.23 -2.35")
+  expect_equal(text(page(root, list(3L, 2L))), "num [1:3] -1.33 -0.0828 0.836")
+  expect_equal(text(page(list(integer(), numeric(), 1:6))),
+               c("int(0)", "num(0)", "int [1:6] 1 2 3 4 5 ..."))
+  expect_equal(text(page(list(c(0, NA_real_, NaN, Inf, -Inf)))),
+               "num [1:5] 0 NA NaN Inf -Inf")
+  # A summary reads only its prefix, including for compact ALTREP sequences.
+  expect_equal(text(page(list(seq_len(1000000000L)))),
+               "int [1:1000000000] 1 2 3 4 5 ...")
+  options(digits = 22L)
+  expect_equal(text(page(list(values))), "num [1:5] -1.33 -0.0828 0.836 1.23 -2.35")
+  options(digits = 3L)
   expect_identical(numbers, c(
     1.23456789012345, 1.54e-100, -6.65e-13, 1.23456789012345e14, 0, NA_real_, NaN, Inf, -Inf
   ))

From f1968b6f5cc9cf0a2771a257f7905d51249b2dea Mon Sep 17 00:00:00 2001
From: Kun Ren <renkun@outlook.com>
Date: Wed, 7 Oct 2026 00:03:38 +0800
Subject: [PATCH 5/5] fix(interactive): isolate nested viewers for each list
 output

---
 sess/R/interactive.R                     |  3 +-
 src/listViewer.ts                        |  2 +-
 src/test/node/interactiveRuntime.test.ts | 42 ++++++++++++++++++++++++
 3 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/sess/R/interactive.R b/sess/R/interactive.R
index f5ac6358a..03e935025 100644
--- a/sess/R/interactive.R
+++ b/sess/R/interactive.R
@@ -403,7 +403,8 @@ interactive_execute <- function(id, code, source = NULL) {
   }
   if (is.list(value) && !is.object(value)) {
     view_id <- dataview_new_id()
-    root <- listview_state(value, "List", "List")
+    # Nested panels reuse the root's owner; separate cell results must stay independent.
+    root <- listview_state(value, "List", paste0("interactive:", view_id))
     dataview_set_state(view_id, root)
     preview <- get_workspace_children(view_id = view_id)
     .interactive_event("display", c(list(kind = "list", viewId = view_id,
diff --git a/src/listViewer.ts b/src/listViewer.ts
index 117d43735..670966074 100644
--- a/src/listViewer.ts
+++ b/src/listViewer.ts
@@ -212,7 +212,7 @@ export function createListViewer(
     };
 }
 
-/** Script shared by the list webview and its interaction tests. */
+/** Panel wrapper and its interaction tests. Keep panel focus/blur hooks here. */
 export function getListViewerScript(documentGeneration: number, initial: ListViewNavigation = {
     title: '', path: [], breadcrumbs: [{ label: '', path: [] }],
 }): string {
diff --git a/src/test/node/interactiveRuntime.test.ts b/src/test/node/interactiveRuntime.test.ts
index 7deb999dc..782bfad45 100644
--- a/src/test/node/interactiveRuntime.test.ts
+++ b/src/test/node/interactiveRuntime.test.ts
@@ -318,6 +318,48 @@ stopifnot(identical(actual, expected))`);
         assert.deepStrictEqual((await client.snapshot()).events.find(event => event.seq === output.seq)?.data, output.data);
     });
 
+    test('nested table viewers from separate list cells stay independent', async () => {
+        const lists: SessionEvent[] = [];
+        for (const value of [11, 21]) {
+            const id = await submit(`list(nested=list(first=data.frame(value=${value}), second=data.frame(value=${value + 1})))`);
+            assert.strictEqual((await finished(id)).state, 'success');
+            const output = events.find(event => event.executionId === id && event.data.kind === 'list');
+            assert.ok(output); lists.push(output);
+        }
+        assert.notStrictEqual(lists[0].data.viewId, lists[1].data.viewId);
+
+        const openTable = async (output: SessionEvent, index: number): Promise<string> => {
+            const start = events.length;
+            assert.strictEqual(await client.request('inspect', { method: 'listview_view', params: {
+                view_id: output.data.viewId, path: [1], index,
+            } }), true);
+            await until(() => events.slice(start).some(event => event.type === 'viewer'));
+            const event = events.slice(start).find(event => event.type === 'viewer'); assert.ok(event);
+            const params = event.data.params as { source: string; title: string; view_id: string };
+            assert.strictEqual(params.source, 'table');
+            assert.strictEqual(params.title, `List$nested$${index === 1 ? 'first' : 'second'}`);
+            return params.view_id;
+        };
+        const tableValue = async (viewId: string): Promise<number> => {
+            const page = await client.request<{ rows: Record<string, number>[] }>('inspect', {
+                method: 'dataview_page', params: { view_id: viewId, startRow: 0, endRow: 1 },
+            });
+            return page.rows[0]['1'];
+        };
+
+        const first = await openTable(lists[0], 1);
+        const second = await openTable(lists[1], 1);
+        assert.notStrictEqual(first, second, 'Each list cell owns its nested table viewer');
+        assert.strictEqual(await tableValue(first), 11);
+        assert.strictEqual(await tableValue(second), 21);
+        assert.strictEqual(await openTable(lists[0], 2), first, 'Tables within one list reuse its viewer');
+        assert.strictEqual(await tableValue(first), 12);
+        assert.strictEqual(await tableValue(second), 21, 'Opening another table in the first cell preserves the second');
+        assert.strictEqual(await openTable(lists[1], 2), second);
+        assert.strictEqual(await tableValue(second), 22);
+        assert.strictEqual(await tableValue(first), 12, 'The first cell remains independently browsable');
+    });
+
     test('huge tables keep bounded snapshots and page the full data without materializing it', async () => {
         const id = await submit(`n <- 832976871L
 huge <- structure(rep(list(seq_len(n)), 23L), names=paste0("x", 1:23),