Fred-Wu · Oct 8, 2026 · Oct 7, 2026 · Oct 7, 2026 · Oct 8, 2026
diff --git a/src/dataViewer.ts b/src/dataViewer.ts
@@ -1,5 +1,7 @@
 'use strict';
 
+import { viewerSessionStyle } from './viewerSession';
+
 export function getDataViewerStyle(): string {
     return `
     body {
@@ -8,11 +10,15 @@ export function getDataViewerStyle(): string {
     }
     #gridContainer { position: relative; flex: 1; min-height: 0; }
     #viewerToolbar {
-        display: flex; align-items: center; flex-wrap: wrap; gap: 6px;
+        display: flex; align-items: flex-start; gap: 6px;
         padding: 6px 8px; border-bottom: 1px solid var(--vscode-panel-border);
         background: var(--vscode-editor-background); color: var(--vscode-foreground);
         font: var(--vscode-font-size, 13px) var(--vscode-font-family, sans-serif);
     }
+    #viewerControls {
+        display: flex; align-items: center; flex-wrap: wrap; gap: 6px;
+        flex: 1; min-width: 0;
+    }
     #viewerToolbar button {
         padding: 4px 8px; border: 1px solid transparent; border-radius: 3px;
         background: var(--vscode-button-secondaryBackground); color: var(--vscode-button-secondaryForeground);
@@ -24,21 +30,31 @@ export function getDataViewerStyle(): string {
     #viewerToolbar button:focus-visible, #columnPanel :focus-visible {
         outline: 1px solid var(--vscode-focusBorder); outline-offset: 2px;
     }
-    #viewerRowCount { margin-left: auto; font-size: 12px; color: var(--vscode-descriptionForeground); }
+    #viewerInfo {
+        display: flex; align-items: center; gap: 12px; padding-top: 5px;
+        flex-shrink: 0; white-space: nowrap;
+        font-size: 12px; color: var(--vscode-descriptionForeground);
+    }
+    ${viewerSessionStyle}
     .dataview-na { color: var(--vscode-descriptionForeground); font-style: italic; opacity: 0.75; }
     `;
 }
 
-export function getDataViewerToolbarHtml(): string {
+export function getDataViewerToolbarHtml(sessionHtml = ''): string {
     return `
     <div id="viewerToolbar" role="group" aria-label="Data viewer controls">
+        <div id="viewerControls">
         <button id="columnPanelToggle" type="button" aria-controls="columnPanel" aria-expanded="false">Columns</button>
         <button id="viewerFilters" type="button" aria-pressed="false" title="Show filters below the headers. Press Enter to apply text and number filters.">Filters</button>
         <button id="viewerClearFilters" type="button" disabled>Clear filters</button>
         <button id="viewerAutoSize" type="button" aria-pressed="false" title="Size columns to their loaded contents">Size to content</button>
         <button id="viewerFit" type="button" aria-pressed="true" title="Keep columns fitted to the available width">Fit width</button>
         <button id="viewerReset" type="button" title="Reset column layout, sorting, filters and page size">Reset view</button>
-        <span id="viewerRowCount" role="status" aria-live="polite"></span>
+        </div>
+        <div id="viewerInfo">
+            <span id="viewerRowCount" role="status" aria-live="polite"></span>
+            ${sessionHtml}
+        </div>
     </div>
     `;
 }

diff --git a/src/interactive/manager.ts b/src/interactive/manager.ts
@@ -781,6 +781,7 @@ export class InteractiveManager implements vscode.Disposable, vscode.TreeDataPro
         const target = session.registerSessionTransport(`${manifest.id}:${manifest.generation}`, manifest.host, manifest.directory, data =>
             client.request('inspect', { method: data.method, params: data.params ?? {} }, data.method === 'hover' || data.method === 'completion' ? 250 : 6000));
         target.pid = String(manifest.rPid ?? ''); target.rVer = manifest.rVersion ?? '';
+        target.processExited = manifest.status === 'exited';
         target.rPath = manifest.rPath; target.libraryPaths = manifest.libraryPaths;
         target.label = manifest.label;
         target.execute = async code => {
@@ -829,6 +830,8 @@ export class InteractiveManager implements vscode.Disposable, vscode.TreeDataPro
         view.executions.clear();
         for (const cell of view.notebook.getCells()) { session.unbindSessionDocument(cell.document.uri); }
         view.client.manifest = snapshot.manifest;
+        view.target.pid = String(snapshot.manifest.rPid ?? ''); view.target.rVer = snapshot.manifest.rVersion ?? '';
+        view.target.processExited = snapshot.manifest.status === 'exited';
         view.target.rPath = snapshot.manifest.rPath; view.target.libraryPaths = snapshot.manifest.libraryPaths;
         view.base = snapshot.manifest.assetBase ? (await vscode.env.asExternalUri(vscode.Uri.parse(snapshot.manifest.assetBase))).toString(true) : '';
         view.model.restore(snapshot);
@@ -927,6 +930,7 @@ export class InteractiveManager implements vscode.Disposable, vscode.TreeDataPro
         this.updateStatus();
         if (event.type === 'state') {
             view.client.manifest.status = event.data.status as SessionManifest['status'];
+            view.target.processExited = event.data.status === 'exited';
             view.client.manifest.rPid = typeof event.data.rPid === 'number' ? event.data.rPid : undefined;
             view.client.manifest.rVersion = typeof event.data.rVersion === 'string' ? event.data.rVersion : undefined;
             view.client.manifest.ended = typeof event.data.ended === 'number' ? event.data.ended : undefined;
@@ -1481,6 +1485,7 @@ export class InteractiveManager implements vscode.Disposable, vscode.TreeDataPro
             const snapshot = await view.client.snapshot();
             view.client.manifest = snapshot.manifest;
             target.pid = String(snapshot.manifest.rPid ?? ''); target.rVer = snapshot.manifest.rVersion ?? '';
+            target.processExited = snapshot.manifest.status === 'exited';
             target.rPath = snapshot.manifest.rPath; target.libraryPaths = snapshot.manifest.libraryPaths;
             view.prompts.clear();
             if (snapshot.workspace) { target.workspaceData = snapshot.workspace as unknown as session.WorkspaceData; }

diff --git a/src/listViewer.ts b/src/listViewer.ts
@@ -1,5 +1,7 @@
 /// <reference lib="dom" />
 
+import { viewerSessionStyle } from './viewerSession';
+
 export interface ListViewNavigation {
     title: string;
     path: number[];
@@ -249,6 +251,8 @@ 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; }
+    ${viewerSessionStyle}
+    .r-list-viewer .viewer-session { margin-left: auto; }
     .r-list-viewer .codicon { flex-shrink: 0; }
     .r-list-viewer .breadcrumbs {
         display: flex;

diff --git a/src/session.ts b/src/session.ts
@@ -13,6 +13,7 @@ import { config, readContent, setContext, UriIcon } from './util';
 import * as rTerminal from './rTerminal';
 import { getProcessAncestors } from './processTree';
 import { TerminalSessionRegistry } from './terminalSessionRegistry';
+import { SessionProcessMonitor } from './sessionProcessMonitor';
 import { purgeAddinPickerItems, RSEditOperation, RSRange } from './rstudioapi';
 
 import { extensionContext, rWorkspace, globalRHelp, globalPlotManager, sessionStatusBarItem, enableSessionWatcher } from './extension';
@@ -23,6 +24,7 @@ import { showWebView } from './webViewer';
 import { getListViewerScript, listViewerStyle, ListViewNavigation } from './listViewer';
 import { getDataViewerScript, getDataViewerStyle, getDataViewerToolbarHtml } from './dataViewer';
 import { getDataViewerColumnPanelHtml, getDataViewerColumnPanelScript, getDataViewerColumnPanelStyle } from './dataViewerColumnPanel';
+import { formatSessionLabel, getViewerSessionScript } from './viewerSession';
 
 export interface SessionInfo {
     version: string;
@@ -57,6 +59,12 @@ interface IpcSocket extends net.Socket {
 }
 
 export class Session {
+    private exited = false;
+    public get processExited(): boolean { return this.exited; }
+    public set processExited(value: boolean) {
+        this.exited = value;
+        if (value) { sessionProcessMonitor.markExited(this); }
+    }
     public label?: string;
     public workspaceUnavailable?: string;
     public execute?: (code: string) => Promise<void>;
@@ -105,6 +113,7 @@ export let workspaceFile: string;
 const SESS_PROTOCOL_VERSION = 2;
 
 const sessions = new Map<string, Session>();
+const sessionProcessMonitor = new SessionProcessMonitor<Session>(isLocalHost);
 // Only the newest handshake for a stable ID may commit after terminal discovery.
 const pendingSessionAttachments = new Map<string, IpcSocket>();
 const terminalRegistry = new TerminalSessionRegistry<Session, vscode.Terminal>(
@@ -1109,7 +1118,7 @@ export async function showDataView(
                 }
                 existing.title = title;
                 existing.reveal(existing.viewColumn, true);
-                existing.webview.html = await getTableHtml(existing.webview, undefined, title);
+                existing.webview.html = await getTableHtml(existing.webview, undefined, title, sessionId);
                 return;
             }
         }
@@ -1126,11 +1135,12 @@ export async function showDataView(
                 localResourceRoots: [Uri.file(resDir)],
             });
         panel.iconPath = new UriIcon('open-preview');
+        attachViewerSessionBridge(panel, sessionId);
         if (viewId) {
             registerDataViewPanel(panel, panelKey, viewId, sessionId, stateGeneration);
             attachDynamicDataViewBridge(panel, viewId, sessionId);
         }
-        const content = await getTableHtml(panel.webview, file || undefined, title);
+        const content = await getTableHtml(panel.webview, file || undefined, title, sessionId);
         panel.webview.html = content;
     } else if (source === 'list') {
         if (viewId) {
@@ -1142,7 +1152,7 @@ export async function showDataView(
                 existing.title = title;
                 existing.reveal(existing.viewColumn, true);
                 existing.webview.html = getListHtml(
-                    existing.webview, title, navigation
+                    existing.webview, title, navigation, sessionId
                 );
                 return;
             }
@@ -1160,6 +1170,7 @@ export async function showDataView(
                 localResourceRoots: [Uri.file(resDir)],
             });
         panel.iconPath = new UriIcon('preview');
+        attachViewerSessionBridge(panel, sessionId);
         if (viewId) {
             registerDataViewPanel(panel, panelKey, viewId, sessionId, stateGeneration);
             const webview = panel.webview;
@@ -1214,7 +1225,7 @@ export async function showDataView(
             });
         }
         panel.webview.html = getListHtml(
-            panel.webview, title, navigation
+            panel.webview, title, navigation, sessionId
         );
     } else {
         await commands.executeCommand('vscode.open', Uri.file(file), {
@@ -1226,7 +1237,41 @@ export async function showDataView(
     console.info('[showDataView] Done');
 }
 
-export async function getTableHtml(webview: Webview, file: string | undefined, title: string): Promise<string> {
+function getViewerSessionHtml(sessionId: string | null): string {
+    const owner = sessions.get(sessionId ?? '');
+    if (!owner) { return ''; }
+    const exited = sessionProcessMonitor.hasExited(owner);
+    if (!exited && (!owner.pid || !owner.rVer)) { return ''; }
+    const info = escapeHtml(exited ? 'R: (not attached)' : formatSessionLabel(owner.rVer, owner.pid));
+    return `<span class="viewer-session" role="img" tabindex="0" aria-label="${info}" aria-describedby="viewer-session-tooltip"><span class="codicon codicon-info" aria-hidden="true"></span><span id="viewer-session-tooltip" class="viewer-session-tooltip" role="tooltip">${info}</span></span>`;
+}
+
+function attachViewerSessionBridge(panel: vscode.WebviewPanel, sessionId: string | null): void {
+    const owner = sessions.get(sessionId ?? '');
+    if (!owner || (!sessionProcessMonitor.hasExited(owner) && (!owner.pid || !owner.rVer))) { return; }
+    // Keep the original process identity after detaching, reconnecting or restarting.
+    const sourcePid = owner.pid;
+    const attachedLabel = formatSessionLabel(owner.rVer, sourcePid);
+    const refresh = (force = false) => {
+        const text = source.exited ? 'R: (not attached)' : attachedLabel;
+        if (force || text !== lastLabel) {
+            lastLabel = text;
+            void panel.webview.postMessage({ message: 'viewer-session/update', text });
+        }
+    };
+    const source = sessionProcessMonitor.observe(owner, refresh);
+    let lastLabel = source.exited ? 'R: (not attached)' : attachedLabel;
+    const received = panel.webview.onDidReceiveMessage((message: { message?: string }) => {
+        if (message?.message === 'viewer-session/ready') { refresh(true); }
+    });
+    panel.onDidDispose(() => { source.dispose(); received?.dispose(); });
+}
+
+export async function getTableHtml(
+    webview: Webview, file: string | undefined, title: string, sessionId: string | null = null,
+): Promise<string> {
+    const sessionHtml = getViewerSessionHtml(sessionId);
+    const codicons = webview.asWebviewUri(Uri.file(path.join(resDir, 'codicon.css'))).toString();
     const pageSize = config().get<number>('session.data.pageSize', 500);
     if (!file) {
         const documentGeneration = ++documentGenerationRevision;
@@ -1238,6 +1283,7 @@ export async function getTableHtml(webview: Webview, file: string | undefined, t
     <meta charset="utf-8">
     <meta name="viewport" content="width=device-width, initial-scale=1">
     <title>${escapeHtml(title)}</title>
+    <link rel="stylesheet" href="${codicons}">
     <style media="only screen">
     html, body {
         height: 100%;
@@ -1647,7 +1693,7 @@ export async function getTableHtml(webview: Webview, file: string | undefined, t
             const info = document.createElement('span');
             info.textContent = 'Full data';
             info.title = 'This view retains the full object without a copy. Reference edits may appear here. Reopen from the cell to refresh after edits. Sorting and filtering scan the full data.';
-            document.querySelector('#viewerToolbar').append(info);
+            document.querySelector('#viewerControls').append(info);
         }
         const bigintFields = prepareViewerColumns(columns);
         updateViewerRowCount(filteredRows, totalRows);
@@ -1744,7 +1790,7 @@ export async function getTableHtml(webview: Webview, file: string | undefined, t
     </script>
 </head>
 <body>
-    ${getDataViewerToolbarHtml()}
+    ${getDataViewerToolbarHtml(sessionHtml)}
     <div id="gridContainer">
         <div id="myGrid" style="height: 100%;"></div>
         ${getDataViewerColumnPanelHtml()}
@@ -1754,6 +1800,7 @@ export async function getTableHtml(webview: Webview, file: string | undefined, t
             <button id="fetchRetryBtn" type="button">Retry</button>
         </div>
     </div>
+    <script>${getViewerSessionScript()}</script>
 </body>
 </html>
 `;
@@ -1767,6 +1814,7 @@ export async function getTableHtml(webview: Webview, file: string | undefined, t
     <meta charset="utf-8">
     <meta name="viewport" content="width=device-width, initial-scale=1">
     <title>${escapeHtml(title)}</title>
+    <link rel="stylesheet" href="${codicons}">
     <style media="only screen">
     html, body {
         height: 100%;
@@ -1913,11 +1961,12 @@ export async function getTableHtml(webview: Webview, file: string | undefined, t
     </script>
 </head>
 <body onload='onload()'>
-    ${getDataViewerToolbarHtml()}
+    ${getDataViewerToolbarHtml(sessionHtml)}
     <div id="gridContainer">
         <div id="myGrid" style="height: 100%;"></div>
         ${getDataViewerColumnPanelHtml()}
     </div>
+    <script>${getViewerSessionScript()}</script>
 </body>
 </html>
 `;
@@ -1926,7 +1975,8 @@ export async function getTableHtml(webview: Webview, file: string | undefined, t
 export function getListHtml(
     webview: Webview,
     title: string,
-    navigation?: ListViewNavigation
+    navigation?: ListViewNavigation,
+    sessionId: string | null = null,
 ): string {
     const documentGeneration = ++documentGenerationRevision;
     documentGenerations.set(webview, documentGeneration);
@@ -1962,13 +2012,15 @@ export function getListHtml(
         <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>
+        ${getViewerSessionHtml(sessionId)}
     </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: [] }],
     })}
+    ${getViewerSessionScript()}
     </script>
 </body>
 </html>
@@ -2016,8 +2068,7 @@ async function refreshActiveSession(session: Session): Promise<void> {
     workspaceData = session.workspaceData;
 
     if (sessionStatusBarItem) {
-        const version = rVer.replace(/^R (?:version )?/, '').replace(/\s+\(.*/, '');
-        sessionStatusBarItem.text = `R ${version}: ${pid}`;
+        sessionStatusBarItem.text = formatSessionLabel(rVer, pid);
         sessionStatusBarItem.tooltip = `${info.version || rVer}\nProcess ID: ${pid}\nCommand: ${info.command}\nStart time: ${info.start_time}\nClick to attach to active terminal.`;
         sessionStatusBarItem.show();
     }