From 5bdb1ba3d336bc848de1986b2ad62f8ca90f7006 Mon Sep 17 00:00:00 2001 From: "4111978+Fred-Wu@users.noreply.github.com" <4111978+Fred-Wu@users.noreply.github.com> Date: Sun, 20 Sep 2026 16:38:54 +1000 Subject: [PATCH 01/30] Enable viewing nested workspace lists and tables --- package.json | 2 +- sess/R/handlers.R | 13 ++++++++++++- sess/R/server.R | 1 + sess/inst/tinytest/test-dataview.R | 8 ++++++++ src/extension.ts | 2 +- src/workspaceViewer.ts | 14 ++++++++++---- 6 files changed, 33 insertions(+), 7 deletions(-) diff --git a/package.json b/package.json index 1d4d195cd..b247feced 100644 --- a/package.json +++ b/package.json @@ -1354,7 +1354,7 @@ { "command": "r.workspaceViewer.view", "group": "inline", - "when": "view == workspaceViewer && viewItem == rootNode" + "when": "view == workspaceViewer && (viewItem == rootNode || viewItem == viewableNode)" }, { "command": "r.workspaceViewer.remove", diff --git a/sess/R/handlers.R b/sess/R/handlers.R index 7a64089c9..7c266241c 100644 --- a/sess/R/handlers.R +++ b/sess/R/handlers.R @@ -120,6 +120,7 @@ workspace_child_item <- function(object, str, selector) { class = paste(class(object), collapse = ", "), type = typeof(object), has_children = workspace_child_count(object) > 0L, + viewable = is.list(object) || dataview_is_table(object), selector = selector ) } @@ -132,6 +133,16 @@ workspace_child_label <- function(name, index) { } } +handle_workspace_view <- function(name, path = list()) { + title <- paste0(c(name, vapply(path, function(selector) switch(selector$kind, + index = if (!is.null(selector$name) && !is.na(selector$name) && nzchar(selector$name)) paste0("$", selector$name) else paste0("[[", selector$value, "]]"), + name = paste0("$", selector$value), + slot = paste0("@", selector$value) + ), "")), collapse = "") + utils::View(workspace_object(name, path), title = title) + TRUE +} + get_workspace_children <- function(name, path = list(), start = 1L) { tryCatch({ object <- workspace_object(name, path) @@ -188,7 +199,7 @@ get_workspace_children <- function(name, path = list(), start = 1L) { ": ", trimws(try_capture_str(child)) ), - list(kind = "index", value = index) + list(kind = "index", value = index, name = child_name) ) }) } diff --git a/sess/R/server.R b/sess/R/server.R index 86b5f1952..754737f0b 100644 --- a/sess/R/server.R +++ b/sess/R/server.R @@ -451,6 +451,7 @@ dispatch_message <- function(line) { }, "workspace" = function(p) get_workspace_data(), "workspace_children" = function(p) get_workspace_children(p$name, p$path, p$start), + "workspace_view" = function(p) handle_workspace_view(p$name, p$path), "hover" = function(p) handle_hover(p$expr), "completion" = function(p) handle_complete(p$expr, p$trigger), "plot_latest" = function(p) handle_plot_latest(p), diff --git a/sess/inst/tinytest/test-dataview.R b/sess/inst/tinytest/test-dataview.R index 07433a658..a8a21d4c9 100644 --- a/sess/inst/tinytest/test-dataview.R +++ b/sess/inst/tinytest/test-dataview.R @@ -322,3 +322,11 @@ local({ expect_identical(page$rows[["2"]], df$Ozone[c(4L, 3L), , drop = FALSE]) expect_identical(serialize(df, NULL), original) }) + +# Workspace children expose the View action only for supported table objects. +local({ + selector <- list(kind = "index", value = 1L) + expect_true(sess:::workspace_child_item(data.frame(x = 1), "df", selector)$viewable) + expect_true(sess:::workspace_child_item(matrix(1:4, 2), "matrix", selector)$viewable) + expect_true(sess:::workspace_child_item(list(x = 1), "list", selector)$viewable) +}) diff --git a/src/extension.ts b/src/extension.ts index 9c67765b9..a2fce9415 100644 --- a/src/extension.ts +++ b/src/extension.ts @@ -153,7 +153,7 @@ export async function activate(context: vscode.ExtensionContext): Promise node?.label && workspaceViewer.viewItem(node), + 'r.workspaceViewer.view': (node: workspaceViewer.GlobalEnvItem) => node && workspaceViewer.viewItem(node), 'r.workspaceViewer.remove': (node: workspaceViewer.GlobalEnvItem) => node?.label && workspaceViewer.removeItem(node), 'r.workspaceViewer.clear': workspaceViewer.clearWorkspace, 'r.workspaceViewer.load': workspaceViewer.loadWorkspace, diff --git a/src/workspaceViewer.ts b/src/workspaceViewer.ts index 0c08f5df7..a1583253a 100644 --- a/src/workspaceViewer.ts +++ b/src/workspaceViewer.ts @@ -21,6 +21,7 @@ interface WorkspaceChild { class: string; type: string; has_children: boolean; + viewable?: boolean; selector?: WorkspaceSelector; } @@ -161,7 +162,8 @@ export class WorkspaceDataProvider implements TreeDataProvider { child.has_children, element.rootName, child.selector ? [...element.objectPath, child.selector] : element.objectPath, - element.owner + element.owner, + child.viewable ) ); if (page.nextStart !== undefined) { @@ -369,6 +371,7 @@ export class GlobalEnvItem extends TreeItem { rootName?: string, objectPath?: WorkspaceSelector[], public readonly owner?: Session, + viewable?: boolean, ) { super( label, @@ -387,7 +390,7 @@ export class GlobalEnvItem extends TreeItem { ); this.tooltip = this.getTooltip(label, rClass, treeLevel); this.iconPath = this.getIcon(type, dim); - this.contextValue = treeLevel === 0 ? 'rootNode' : `childNode${this.treeLevel}`; + this.contextValue = treeLevel === 0 ? 'rootNode' : viewable ? 'viewableNode' : `childNode${this.treeLevel}`; } private getDescription(dim: number[] | undefined, str: string, rClass: string, type: string): string { @@ -492,8 +495,11 @@ export async function loadWorkspace(): Promise { } export async function viewItem(node: GlobalEnvItem): Promise { - if (node.owner && node.label) { - await runWorkspaceCode(`View(get(${JSON.stringify(node.label)}, envir = .GlobalEnv, inherits = FALSE), title = ${JSON.stringify(node.label)})`, node.owner); + if (node.owner && !node.owner.workspaceUnavailable && node.rootName) { + await sessionRequest({ + method: 'workspace_view', + params: { name: node.rootName, path: node.objectPath }, + }, node.owner); } } From 54c166d5d79a7314265a3ba506852d4bc66541ea Mon Sep 17 00:00:00 2001 From: "4111978+Fred-Wu@users.noreply.github.com" <4111978+Fred-Wu@users.noreply.github.com> Date: Sun, 20 Sep 2026 16:39:00 +1000 Subject: [PATCH 02/30] Show shallow list summaries with child navigation --- sess/R/handlers.R | 18 +++++++ sess/R/hooks.R | 21 +++++++- sess/R/server.R | 1 + src/session.ts | 124 +++++++++++++++++++++++++++++----------------- 4 files changed, 116 insertions(+), 48 deletions(-) diff --git a/sess/R/handlers.R b/sess/R/handlers.R index 7c266241c..7ddf74966 100644 --- a/sess/R/handlers.R +++ b/sess/R/handlers.R @@ -211,6 +211,24 @@ get_workspace_children <- function(name, path = list(), start = 1L) { }, error = function(e) list(children = I(list()), next_start = NULL)) } +handle_listview_view <- function(view_id, index) { + state <- .sess_env$dataviews[[as.character(view_id)]] + index <- as.integer(index) + if (is.null(state) || !identical(state$type, "list") || + is.na(index) || index < 1L || index > length(state$data)) { + return(FALSE) + } + child_names <- names(state$data) + child_name <- if (is.null(child_names)) NULL else child_names[[index]] + title <- if (!is.null(child_name) && !is.na(child_name) && nzchar(child_name)) { + paste0(state$title, "$", child_name) + } else { + paste0(state$title, "[[", index, "]]") + } + utils::View(state$data[[index]], title = title) + TRUE +} + handle_hover <- function(expr_str) { tryCatch( { diff --git a/sess/R/hooks.R b/sess/R/hooks.R index 62e3ed902..4577b70b0 100644 --- a/sess/R/hooks.R +++ b/sess/R/hooks.R @@ -134,13 +134,30 @@ runtime_start <- function(use_rstudioapi = TRUE, view_id = registration$view_id )) } else if (is.list(x)) { + view_id <- dataview_new_id() + .sess_env$dataviews[[view_id]] <- list( + type = "list", + data = x, + title = paste(as.character(title), collapse = "\n") + ) + x_names <- names(x) + children <- lapply(seq_along(x), function(index) { + child <- x[[index]] + list( + label = workspace_child_label(if (is.null(x_names)) NULL else x_names[[index]], index), + str = trimws(try_capture_str(child)), + viewable = is.list(child) || dataview_is_table(child), + index = index + ) + }) file_path <- tempfile(tmpdir = .sess_env$tempdir, fileext = ".json") - jsonlite::write_json(x, file_path, auto_unbox = TRUE, null = "null", na = "string") + jsonlite::write_json(list(children = I(children)), file_path, auto_unbox = TRUE) notify_client("dataview", list( title = title, file = file_path, source = "list", - type = "json" + type = "json", + view_id = view_id )) } else { code <- if (is.primitive(x)) utils::capture.output(print(x)) else deparse(x) diff --git a/sess/R/server.R b/sess/R/server.R index 754737f0b..353859879 100644 --- a/sess/R/server.R +++ b/sess/R/server.R @@ -455,6 +455,7 @@ dispatch_message <- function(line) { "hover" = function(p) handle_hover(p$expr), "completion" = function(p) handle_complete(p$expr, p$trigger), "plot_latest" = function(p) handle_plot_latest(p), + "listview_view" = function(p) handle_listview_view(p$view_id, p$index), "dataview_init" = function(p) handle_dataview_init(p), "dataview_page" = function(p) handle_dataview_page(p), "dataview_dispose" = function(p) handle_dataview_dispose(p) diff --git a/src/session.ts b/src/session.ts index 14ef5becc..280b726d1 100644 --- a/src/session.ts +++ b/src/session.ts @@ -1060,6 +1060,22 @@ export async function showDataView(source: string, type: string, title: string, }); const content = await getListHtml(panel.webview, file, title); panel.iconPath = new UriIcon('open-preview'); + if (viewId) { + panel.webview.onDidReceiveMessage((message: { message?: string; index?: number }) => { + if (message.message === 'listview/view' && typeof message.index === 'number' && Number.isInteger(message.index)) { + void sessionRequest({ + method: 'listview_view', + params: { view_id: viewId, index: message.index }, + }); + } + }); + panel.onDidDispose(() => { + void sessionRequest({ + method: 'dataview_dispose', + params: { view_id: viewId }, + }); + }); + } panel.webview.html = content; } else { await commands.executeCommand('vscode.open', Uri.file(file), { @@ -1764,7 +1780,7 @@ export async function getTableHtml(webview: Webview, file: string | undefined, t } export async function getListHtml(webview: Webview, file: string, title: string): Promise { - const content = await readContent(file, 'utf8'); + const content = (await readContent(file, 'utf8')).replace(/ @@ -1773,64 +1789,80 @@ export async function getListHtml(webview: Webview, file: string, title: string) ${escapeHtml(title)} - - - - - - 

+    

+    
 
 
 `;

From 0588cde74354411e439d25b30cc2551776ac8824 Mon Sep 17 00:00:00 2001
From: "4111978+Fred-Wu@users.noreply.github.com"
 <4111978+Fred-Wu@users.noreply.github.com>
Date: Sun, 20 Sep 2026 16:39:07 +1000
Subject: [PATCH 03/30] Match list viewer actions to workspace View icons

---
 images/icons/dark/open-preview-codicon.svg  |  1 +
 images/icons/light/open-preview-codicon.svg |  1 +
 src/session.ts                              | 32 +++++++++++++++++----
 3 files changed, 28 insertions(+), 6 deletions(-)
 create mode 100644 images/icons/dark/open-preview-codicon.svg
 create mode 100644 images/icons/light/open-preview-codicon.svg

diff --git a/images/icons/dark/open-preview-codicon.svg b/images/icons/dark/open-preview-codicon.svg
new file mode 100644
index 000000000..5dc0bba6b
--- /dev/null
+++ b/images/icons/dark/open-preview-codicon.svg
@@ -0,0 +1 @@
+
diff --git a/images/icons/light/open-preview-codicon.svg b/images/icons/light/open-preview-codicon.svg
new file mode 100644
index 000000000..9e363217a
--- /dev/null
+++ b/images/icons/light/open-preview-codicon.svg
@@ -0,0 +1 @@
+
diff --git a/src/session.ts b/src/session.ts
index 280b726d1..f108ec79e 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -1056,7 +1056,7 @@ export async function showDataView(source: string, type: string, title: string,
                 enableScripts: true,
                 enableFindWidget: true,
                 retainContextWhenHidden: true,
-                localResourceRoots: [Uri.file(resDir)],
+                localResourceRoots: [Uri.file(resDir), Uri.file(extensionContext.asAbsolutePath('images/icons'))],
             });
         const content = await getListHtml(panel.webview, file, title);
         panel.iconPath = new UriIcon('open-preview');
@@ -1781,6 +1781,9 @@ export async function getTableHtml(webview: Webview, file: string | undefined, t
 
 export async function getListHtml(webview: Webview, file: string, title: string): Promise {
     const content = (await readContent(file, 'utf8')).replace(/
@@ -1819,14 +1822,29 @@ export async function getListHtml(webview: Webview, file: string, title: string)
         white-space: pre-wrap;
     }
     button {
+        display: flex;
+        align-items: center;
         border: 0;
-        padding: 2px 8px;
-        color: var(--vscode-button-foreground);
-        background-color: var(--vscode-button-background);
+        padding: 2px;
+        color: var(--vscode-foreground);
+        background: transparent;
         cursor: pointer;
     }
     button:hover {
-        background-color: var(--vscode-button-hoverBackground);
+        background-color: var(--vscode-toolbar-hoverBackground);
+    }
+    button img {
+        width: 16px;
+        height: 16px;
+    }
+    .light-icon {
+        display: none;
+    }
+    body.vscode-light .dark-icon {
+        display: none;
+    }
+    body.vscode-light .light-icon {
+        display: block;
     }
     
 
@@ -1853,7 +1871,9 @@ export async function getListHtml(webview: Webview, file: string, title: string)
 
         if (item.viewable) {
             const button = document.createElement('button');
-            button.textContent = 'View';
+            button.title = 'View';
+            button.setAttribute('aria-label', 'View');
+            button.innerHTML = '';
             button.addEventListener('click', () => {
                 vscode.postMessage({ message: 'listview/view', index: item.index });
             });

From dd26ffa0c2cdb372e7b3350fa9b64321aa598a69 Mon Sep 17 00:00:00 2001
From: "4111978+Fred-Wu@users.noreply.github.com"
 <4111978+Fred-Wu@users.noreply.github.com>
Date: Sun, 20 Sep 2026 16:39:13 +1000
Subject: [PATCH 04/30] Reuse list viewer panels by title

---
 sess/R/hooks.R | 20 +++++++++++---------
 src/session.ts | 25 +++++++++++++++++++------
 2 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/sess/R/hooks.R b/sess/R/hooks.R
index 4577b70b0..c1e50c7db 100644
--- a/sess/R/hooks.R
+++ b/sess/R/hooks.R
@@ -110,21 +110,24 @@ runtime_start <- function(use_rstudioapi = TRUE,
       return(invisible(NULL))
     }
 
-    if (dataview_is_table(x)) {
+    view_type <- if (dataview_is_table(x)) "table" else if (is.list(x)) "list" else "object"
+    if (view_type != "object") {
       title_key <- paste(as.character(title), collapse = "\n")
+      registry_key <- paste0(view_type, ":", title_key)
       dataview_registry <- .sess_env$dataview_registry
-      has_view_id <- nzchar(title_key) &&
-        exists(title_key, envir = dataview_registry, inherits = FALSE)
-      view_id <- if (has_view_id) {
-        get(title_key, envir = dataview_registry, inherits = FALSE)
+      view_id <- if (nzchar(title_key) &&
+                       exists(registry_key, envir = dataview_registry, inherits = FALSE)) {
+        get(registry_key, envir = dataview_registry, inherits = FALSE)
       } else {
         id <- dataview_new_id()
         if (nzchar(title_key)) {
-          assign(title_key, id, envir = dataview_registry)
+          assign(registry_key, id, envir = dataview_registry)
         }
         id
       }
+    }
 
+    if (view_type == "table") {
       registration <- dataview_register(x, view_id = view_id)
 
       notify_client("dataview", list(
@@ -133,12 +136,11 @@ runtime_start <- function(use_rstudioapi = TRUE,
         type = "json",
         view_id = registration$view_id
       ))
-    } else if (is.list(x)) {
-      view_id <- dataview_new_id()
+    } else if (view_type == "list") {
       .sess_env$dataviews[[view_id]] <- list(
         type = "list",
         data = x,
-        title = paste(as.character(title), collapse = "\n")
+        title = title_key
       )
       x_names <- names(x)
       children <- lapply(seq_along(x), function(index) {
diff --git a/src/session.ts b/src/session.ts
index f108ec79e..d114555c8 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -1047,6 +1047,16 @@ export async function showDataView(source: string, type: string, title: string,
         const content = await getTableHtml(panel.webview, file || undefined, title);
         panel.webview.html = content;
     } else if (source === 'list') {
+        if (viewId) {
+            const existing = dynamicDataViewPanels.get(viewId);
+            if (existing) {
+                existing.title = title;
+                existing.reveal(ViewColumn[viewer as keyof typeof ViewColumn], true);
+                existing.webview.html = await getListHtml(existing.webview, file, title);
+                return;
+            }
+        }
+
         const panel = window.createWebviewPanel('dataview', title,
             {
                 preserveFocus: true,
@@ -1056,11 +1066,11 @@ export async function showDataView(source: string, type: string, title: string,
                 enableScripts: true,
                 enableFindWidget: true,
                 retainContextWhenHidden: true,
-                localResourceRoots: [Uri.file(resDir), Uri.file(extensionContext.asAbsolutePath('images/icons'))],
+                localResourceRoots: [Uri.file(extensionContext.asAbsolutePath('images/icons'))],
             });
-        const content = await getListHtml(panel.webview, file, title);
         panel.iconPath = new UriIcon('open-preview');
         if (viewId) {
+            dynamicDataViewPanels.set(viewId, panel);
             panel.webview.onDidReceiveMessage((message: { message?: string; index?: number }) => {
                 if (message.message === 'listview/view' && typeof message.index === 'number' && Number.isInteger(message.index)) {
                     void sessionRequest({
@@ -1070,13 +1080,16 @@ export async function showDataView(source: string, type: string, title: string,
                 }
             });
             panel.onDidDispose(() => {
+                if (dynamicDataViewPanels.get(viewId) === panel) {
+                    dynamicDataViewPanels.delete(viewId);
+                }
                 void sessionRequest({
                     method: 'dataview_dispose',
                     params: { view_id: viewId },
                 });
             });
         }
-        panel.webview.html = content;
+        panel.webview.html = await getListHtml(panel.webview, file, title);
     } else {
         await commands.executeCommand('vscode.open', Uri.file(file), {
             preserveFocus: true,
@@ -1780,10 +1793,10 @@ export async function getTableHtml(webview: Webview, file: string | undefined, t
 }
 
 export async function getListHtml(webview: Webview, file: string, title: string): Promise {
-    const content = (await readContent(file, 'utf8')).replace(/

From c66d423d71ebf0fbf027a44c8f6f45b0e2912aa0 Mon Sep 17 00:00:00 2001
From: "4111978+Fred-Wu@users.noreply.github.com"
 <4111978+Fred-Wu@users.noreply.github.com>
Date: Sun, 20 Sep 2026 20:16:49 +1000
Subject: [PATCH 05/30] Nested View icons now appear for all supported values

---
 sess/R/handlers.R                  | 28 +++++++++++++++-----
 sess/R/hooks.R                     | 41 +++++++++++++++++++++++++-----
 sess/inst/tinytest/test-dataview.R |  9 ++++++-
 3 files changed, 63 insertions(+), 15 deletions(-)

diff --git a/sess/R/handlers.R b/sess/R/handlers.R
index 7ddf74966..b3e2b1c70 100644
--- a/sess/R/handlers.R
+++ b/sess/R/handlers.R
@@ -120,7 +120,7 @@ workspace_child_item <- function(object, str, selector) {
     class = paste(class(object), collapse = ", "),
     type = typeof(object),
     has_children = workspace_child_count(object) > 0L,
-    viewable = is.list(object) || dataview_is_table(object),
+    viewable = TRUE,
     selector = selector
   )
 }
@@ -213,19 +213,33 @@ get_workspace_children <- function(name, path = list(), start = 1L) {
 
 handle_listview_view <- function(view_id, index) {
   state <- .sess_env$dataviews[[as.character(view_id)]]
+  if (is.null(state) || !identical(state$type, "list")) {
+    return(FALSE)
+  }
   index <- as.integer(index)
-  if (is.null(state) || !identical(state$type, "list") ||
-      is.na(index) || index < 1L || index > length(state$data)) {
+  child_count <- if (state$kind == "index") length(state$data) else length(state$names)
+  if (length(index) != 1L || is.na(index) || index < 1L || index > child_count) {
     return(FALSE)
   }
-  child_names <- names(state$data)
-  child_name <- if (is.null(child_names)) NULL else child_names[[index]]
-  title <- if (!is.null(child_name) && !is.na(child_name) && nzchar(child_name)) {
+  child_name <- if (is.null(state$names)) NULL else state$names[[index]]
+  if (state$kind == "name" &&
+        (!exists(child_name, envir = state$data, inherits = FALSE) ||
+           bindingIsActive(child_name, state$data))) {
+    return(FALSE)
+  }
+  child <- switch(state$kind,
+    name = get(child_name, envir = state$data, inherits = FALSE),
+    slot = methods::slot(state$data, child_name),
+    index = state$data[[index]]
+  )
+  title <- if (state$kind == "slot") {
+    paste0(state$title, "@", child_name)
+  } else if (!is.null(child_name) && !is.na(child_name) && nzchar(child_name)) {
     paste0(state$title, "$", child_name)
   } else {
     paste0(state$title, "[[", index, "]]")
   }
-  utils::View(state$data[[index]], title = title)
+  utils::View(child, title = title)
   TRUE
 }
 
diff --git a/sess/R/hooks.R b/sess/R/hooks.R
index c1e50c7db..5f8cd92ba 100644
--- a/sess/R/hooks.R
+++ b/sess/R/hooks.R
@@ -110,7 +110,13 @@ runtime_start <- function(use_rstudioapi = TRUE,
       return(invisible(NULL))
     }
 
-    view_type <- if (dataview_is_table(x)) "table" else if (is.list(x)) "list" else "object"
+    view_type <- if (dataview_is_table(x)) {
+      "table"
+    } else if (is.list(x) || is.environment(x) || isS4(x)) {
+      "list"
+    } else {
+      "object"
+    }
     if (view_type != "object") {
       title_key <- paste(as.character(title), collapse = "\n")
       registry_key <- paste0(view_type, ":", title_key)
@@ -137,18 +143,39 @@ runtime_start <- function(use_rstudioapi = TRUE,
         view_id = registration$view_id
       ))
     } else if (view_type == "list") {
+      child_kind <- if (is.environment(x)) "name" else if (isS4(x)) "slot" else "index"
+      x_names <- switch(child_kind,
+        name = workspace_env_names(x),
+        slot = methods::slotNames(x),
+        index = names(x)
+      )
       .sess_env$dataviews[[view_id]] <- list(
         type = "list",
         data = x,
-        title = title_key
+        title = title_key,
+        kind = child_kind,
+        names = x_names
       )
-      x_names <- names(x)
-      children <- lapply(seq_along(x), function(index) {
-        child <- x[[index]]
+      indices <- if (child_kind == "index") seq_along(x) else seq_along(x_names)
+      children <- lapply(indices, function(index) {
+        child_name <- if (is.null(x_names)) NULL else x_names[[index]]
+        label <- if (child_kind == "slot") {
+          paste0("@ ", child_name)
+        } else {
+          workspace_child_label(child_name, index)
+        }
+        if (child_kind == "name" && bindingIsActive(child_name, x)) {
+          return(list(label = label, str = "(active-binding)", viewable = FALSE, index = index))
+        }
+        child <- switch(child_kind,
+          name = get(child_name, envir = x, inherits = FALSE),
+          slot = methods::slot(x, child_name),
+          index = x[[index]]
+        )
         list(
-          label = workspace_child_label(if (is.null(x_names)) NULL else x_names[[index]], index),
+          label = label,
           str = trimws(try_capture_str(child)),
-          viewable = is.list(child) || dataview_is_table(child),
+          viewable = TRUE,
           index = index
         )
       })
diff --git a/sess/inst/tinytest/test-dataview.R b/sess/inst/tinytest/test-dataview.R
index a8a21d4c9..f611530b8 100644
--- a/sess/inst/tinytest/test-dataview.R
+++ b/sess/inst/tinytest/test-dataview.R
@@ -323,10 +323,17 @@ local({
   expect_identical(serialize(df, NULL), original)
 })
 
-# Workspace children expose the View action only for supported table objects.
+# Workspace children expose View for both structured and text-viewable objects.
 local({
   selector <- list(kind = "index", value = 1L)
   expect_true(sess:::workspace_child_item(data.frame(x = 1), "df", selector)$viewable)
   expect_true(sess:::workspace_child_item(matrix(1:4, 2), "matrix", selector)$viewable)
   expect_true(sess:::workspace_child_item(list(x = 1), "list", selector)$viewable)
+  expect_true(sess:::workspace_child_item(new.env(), "environment", selector)$viewable)
+  expect_true(sess:::workspace_child_item(pairlist(x = 1), "pairlist", selector)$viewable)
+  methods::setClass("list_viewer_test_slots", slots = c(child = "list"))
+  on.exit(methods::removeClass("list_viewer_test_slots"), add = TRUE)
+  object <- methods::new("list_viewer_test_slots", child = list(x = 1))
+  expect_true(sess:::workspace_child_item(object, "S4", selector)$viewable)
+  expect_true(sess:::workspace_child_item(1:3, "vector", selector)$viewable)
 })

From a44eb76e45ac0a87bbb6b4166c3ac498c35da221 Mon Sep 17 00:00:00 2001
From: "4111978+Fred-Wu@users.noreply.github.com"
 <4111978+Fred-Wu@users.noreply.github.com>
Date: Sun, 20 Sep 2026 21:49:25 +1000
Subject: [PATCH 06/30] Load list viewer items on demand using workspace
 pagination

---
 sess/R/handlers.R                  | 116 +++++++++++++++--------------
 sess/R/hooks.R                     |  26 -------
 sess/R/server.R                    |   2 +-
 sess/inst/tinytest/test-dataview.R |  31 ++++++++
 src/session.ts                     | 113 ++++++++++++++++++++--------
 5 files changed, 174 insertions(+), 114 deletions(-)

diff --git a/sess/R/handlers.R b/sess/R/handlers.R
index b3e2b1c70..f810dbc19 100644
--- a/sess/R/handlers.R
+++ b/sess/R/handlers.R
@@ -143,72 +143,76 @@ handle_workspace_view <- function(name, path = list()) {
   TRUE
 }
 
-get_workspace_children <- function(name, path = list(), start = 1L) {
+get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_id = NULL) {
   tryCatch({
-    object <- workspace_object(name, path)
-    child_count <- workspace_child_count(object)
-    if (child_count == 0L) {
-      return(list(children = I(list()), next_start = NULL))
+    if (is.null(view_id)) {
+      object <- workspace_object(name, path)
+      kind <- if (is.environment(object)) "name" else if (isS4(object)) "slot" else "index"
+      child_names <- switch(kind,
+        name = workspace_env_names(object),
+        slot = methods::slotNames(object),
+        index = names(object)
+      )
+    } else {
+      state <- dataview_get_state(view_id)
+      if (!identical(state$type, "list")) stop("Not a list view")
+      object <- state$data
+      kind <- state$kind
+      child_names <- state$names
     }
-
+    child_count <- if (kind == "index") workspace_child_count(object) else length(child_names)
     start <- max(1L, as.integer(start))
     end <- min(child_count, start + workspace_child_page_size - 1L)
     if (start > end) {
       return(list(children = I(list()), next_start = NULL))
     }
 
-    children <- if (is.environment(object)) {
-      child_names <- workspace_env_names(object)[seq.int(start, end)]
-      lapply(child_names, function(child_name) {
-        if (bindingIsActive(child_name, object)) {
-          list(
-            str = paste0("$ ", child_name, ": (active-binding)"),
-            class = "active_binding",
-            type = "active_binding",
-            has_children = FALSE
-          )
+    children <- lapply(seq.int(start, end), function(index) {
+      child_name <- if (is.null(child_names)) NULL else child_names[[index]]
+      label <- if (kind == "slot") {
+        paste0("@ ", child_name)
+      } else {
+        workspace_child_label(child_name, index)
+      }
+      unavailable <- if (kind == "name" && !exists(child_name, envir = object, inherits = FALSE)) {
+        "removed"
+      } else if (kind == "name" && bindingIsActive(child_name, object)) {
+        "active_binding"
+      } else {
+        NULL
+      }
+      if (!is.null(unavailable)) {
+        summary <- if (unavailable == "removed") "(removed)" else "(active-binding)"
+        if (!is.null(view_id)) {
+          return(list(label = label, str = summary, viewable = FALSE, index = index))
+        }
+        return(list(
+          str = paste0(label, ": ", summary), class = unavailable,
+          type = unavailable, has_children = FALSE
+        ))
+      }
+      child <- switch(kind,
+        name = get(child_name, envir = object, inherits = FALSE),
+        slot = methods::slot(object, child_name),
+        index = object[[index]]
+      )
+      summary <- trimws(try_capture_str(child))
+      if (!is.null(view_id)) {
+        list(label = label, str = summary, viewable = TRUE, index = index)
+      } else {
+        selector <- if (kind == "index") {
+          list(kind = kind, value = index, name = child_name)
         } else {
-          child <- get(child_name, envir = object, inherits = FALSE)
-          workspace_child_item(
-            child,
-            paste0("$ ", child_name, ": ", trimws(try_capture_str(child))),
-            list(kind = "name", value = child_name)
-          )
+          list(kind = kind, value = child_name)
         }
-      })
-    } else if (isS4(object)) {
-      child_names <- methods::slotNames(object)[seq.int(start, end)]
-      lapply(child_names, function(child_name) {
-        child <- methods::slot(object, child_name)
-        workspace_child_item(
-          child,
-          paste0("@ ", child_name, ": ", trimws(try_capture_str(child))),
-          list(kind = "slot", value = child_name)
-        )
-      })
-    } else {
-      indices <- seq.int(start, end)
-      child_names <- names(object)
-      lapply(indices, function(index) {
-        child <- object[[index]]
-        child_name <- if (is.null(child_names)) NULL else child_names[[index]]
-        workspace_child_item(
-          child,
-          paste0(
-            workspace_child_label(child_name, index),
-            ": ",
-            trimws(try_capture_str(child))
-          ),
-          list(kind = "index", value = index, name = child_name)
-        )
-      })
-    }
-
-    list(
-      children = I(children),
-      next_start = if (end < child_count) end + 1L else NULL
-    )
-  }, error = function(e) list(children = I(list()), next_start = NULL))
+        workspace_child_item(child, paste0(label, ": ", summary), selector)
+      }
+    })
+    list(children = I(children), next_start = if (end < child_count) end + 1L else NULL)
+  }, error = function(e) {
+    if (!is.null(view_id)) stop(e)
+    list(children = I(list()), next_start = NULL)
+  })
 }
 
 handle_listview_view <- function(view_id, index) {
diff --git a/sess/R/hooks.R b/sess/R/hooks.R
index 5f8cd92ba..ca395fd4a 100644
--- a/sess/R/hooks.R
+++ b/sess/R/hooks.R
@@ -156,34 +156,8 @@ runtime_start <- function(use_rstudioapi = TRUE,
         kind = child_kind,
         names = x_names
       )
-      indices <- if (child_kind == "index") seq_along(x) else seq_along(x_names)
-      children <- lapply(indices, function(index) {
-        child_name <- if (is.null(x_names)) NULL else x_names[[index]]
-        label <- if (child_kind == "slot") {
-          paste0("@ ", child_name)
-        } else {
-          workspace_child_label(child_name, index)
-        }
-        if (child_kind == "name" && bindingIsActive(child_name, x)) {
-          return(list(label = label, str = "(active-binding)", viewable = FALSE, index = index))
-        }
-        child <- switch(child_kind,
-          name = get(child_name, envir = x, inherits = FALSE),
-          slot = methods::slot(x, child_name),
-          index = x[[index]]
-        )
-        list(
-          label = label,
-          str = trimws(try_capture_str(child)),
-          viewable = TRUE,
-          index = index
-        )
-      })
-      file_path <- tempfile(tmpdir = .sess_env$tempdir, fileext = ".json")
-      jsonlite::write_json(list(children = I(children)), file_path, auto_unbox = TRUE)
       notify_client("dataview", list(
         title = title,
-        file = file_path,
         source = "list",
         type = "json",
         view_id = view_id
diff --git a/sess/R/server.R b/sess/R/server.R
index 353859879..f97bec091 100644
--- a/sess/R/server.R
+++ b/sess/R/server.R
@@ -450,7 +450,7 @@ dispatch_message <- function(line) {
         TRUE
       },
       "workspace" = function(p) get_workspace_data(),
-      "workspace_children" = function(p) get_workspace_children(p$name, p$path, p$start),
+      "workspace_children" = function(p) get_workspace_children(p$name, p$path, p$start, p$view_id),
       "workspace_view" = function(p) handle_workspace_view(p$name, p$path),
       "hover" = function(p) handle_hover(p$expr),
       "completion" = function(p) handle_complete(p$expr, p$trigger),
diff --git a/sess/inst/tinytest/test-dataview.R b/sess/inst/tinytest/test-dataview.R
index f611530b8..977121b47 100644
--- a/sess/inst/tinytest/test-dataview.R
+++ b/sess/inst/tinytest/test-dataview.R
@@ -337,3 +337,34 @@ local({
   expect_true(sess:::workspace_child_item(object, "S4", selector)$viewable)
   expect_true(sess:::workspace_child_item(1:3, "vector", selector)$viewable)
 })
+
+# List pages inspect only the requested children, with stable indices across pages.
+local({
+  runtime <- sess:::.sess_env
+  previous <- runtime$dataviews
+  on.exit(runtime$dataviews <- previous, add = TRUE)
+  object <- new.env(parent = emptyenv())
+  child_names <- paste0("item", seq_len(501L))
+  for (name in child_names[1:500]) assign(name, 1L, envir = object)
+  delayedAssign("item501", stop("unrequested binding was evaluated"), assign.env = object)
+  runtime$dataviews$paging_test <- list(
+    type = "list", data = object, kind = "name", names = child_names, title = "object"
+  )
+
+  first <- sess:::get_workspace_children(view_id = "paging_test", start = 1L)
+  expect_length(first$children, 500L)
+  expect_equal(first$next_start, 501L)
+  expect_equal(vapply(first$children, `[[`, 1L, "index"), 1:500)
+
+  # Removing a binding must not shift later indices or fail the next page.
+  rm("item501", envir = object)
+  last <- sess:::get_workspace_children(view_id = "paging_test", start = 501L)
+  expect_equal(last$children[[1L]]$label, "$ item501")
+  expect_false(last$children[[1L]]$viewable)
+  expect_null(last$next_start)
+  makeActiveBinding("item501", function() stop("active binding was evaluated"), object)
+  last <- sess:::get_workspace_children(view_id = "paging_test", start = 501L)
+  expect_equal(last$children[[1L]]$str, "(active-binding)")
+  expect_false(last$children[[1L]]$viewable)
+  expect_length(sess:::get_workspace_children(view_id = "paging_test", start = 502L)$children, 0L)
+})
diff --git a/src/session.ts b/src/session.ts
index d114555c8..51ada9d52 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -1052,7 +1052,7 @@ export async function showDataView(source: string, type: string, title: string,
             if (existing) {
                 existing.title = title;
                 existing.reveal(ViewColumn[viewer as keyof typeof ViewColumn], true);
-                existing.webview.html = await getListHtml(existing.webview, file, title);
+                existing.webview.html = getListHtml(existing.webview, title);
                 return;
             }
         }
@@ -1071,12 +1071,24 @@ export async function showDataView(source: string, type: string, title: string,
         panel.iconPath = new UriIcon('open-preview');
         if (viewId) {
             dynamicDataViewPanels.set(viewId, panel);
-            panel.webview.onDidReceiveMessage((message: { message?: string; index?: number }) => {
+            panel.webview.onDidReceiveMessage(async (message: { message?: string; index?: number; start?: number; requestId?: number }) => {
                 if (message.message === 'listview/view' && typeof message.index === 'number' && Number.isInteger(message.index)) {
                     void sessionRequest({
                         method: 'listview_view',
                         params: { view_id: viewId, index: message.index },
                     });
+                } else if (message.message === 'listview/page' && typeof message.start === 'number' &&
+                    Number.isInteger(message.start) && typeof message.requestId === 'number') {
+                    const page = await sessionRequest({
+                        method: 'workspace_children',
+                        params: { view_id: viewId, start: message.start },
+                    }) as { children?: unknown; next_start?: number | null } | undefined;
+                    void panel.webview.postMessage({
+                        message: 'listview/page',
+                        requestId: message.requestId,
+                        ...page,
+                        error: Array.isArray(page?.children) ? undefined : 'Unable to load items. Check the R session and try again.',
+                    });
                 }
             });
             panel.onDidDispose(() => {
@@ -1089,7 +1101,7 @@ export async function showDataView(source: string, type: string, title: string,
                 });
             });
         }
-        panel.webview.html = await getListHtml(panel.webview, file, title);
+        panel.webview.html = getListHtml(panel.webview, title);
     } else {
         await commands.executeCommand('vscode.open', Uri.file(file), {
             preserveFocus: true,
@@ -1792,8 +1804,7 @@ export async function getTableHtml(webview: Webview, file: string | undefined, t
 `;
 }
 
-export async function getListHtml(webview: Webview, file: string, title: string): Promise {
-    const content = (await fs.readFile(file, 'utf8')).replace(/
 
     

+    
+    

     
 
 

From 82efd24c2237bc4a7ea136cac99c723ac6323a6e Mon Sep 17 00:00:00 2001
From: "4111978+Fred-Wu@users.noreply.github.com"
 <4111978+Fred-Wu@users.noreply.github.com>
Date: Sat, 3 Oct 2026 18:45:35 +1000
Subject: [PATCH 07/30] Improve List Viewer  - add expandable controls for
 nested objects in List Viewer  - associate nested List / Data Viewers with
 their top level object, so only one viewer is used for each viewer type  -
 add navigation controls to go back to the previous view or directly to a
 parent view.

---
 README.md                               |   4 +
 images/icons/arrow-left.svg             |   3 +
 images/icons/chevron-down.svg           |   3 +
 images/icons/chevron-right.svg          |   3 +
 sess/R/handlers.R                       | 198 ++++++++++++++++++----
 sess/R/hooks.R                          |  66 ++++----
 sess/R/server.R                         |   3 +-
 sess/inst/tinytest/test-ipc.R           |   6 +-
 sess/inst/tinytest/test-listview.R      | 172 +++++++++++++++++++
 src/interactive/manager.ts              |   2 +-
 src/listViewer.ts                       | 176 ++++++++++++++++++++
 src/session.ts                          | 182 +++++++++++---------
 src/test/suite/listViewer.test.ts       | 213 ++++++++++++++++++++++++
 src/test/suite/listViewerPanels.test.ts |  79 +++++++++
 14 files changed, 961 insertions(+), 149 deletions(-)
 create mode 100644 images/icons/arrow-left.svg
 create mode 100644 images/icons/chevron-down.svg
 create mode 100644 images/icons/chevron-right.svg
 create mode 100644 sess/inst/tinytest/test-listview.R
 create mode 100644 src/listViewer.ts
 create mode 100644 src/test/suite/listViewer.test.ts
 create mode 100644 src/test/suite/listViewerPanels.test.ts

diff --git a/README.md b/README.md
index a226fd305..5f2c13bf1 100644
--- a/README.md
+++ b/README.md
@@ -138,3 +138,7 @@ Call `View(x)` to open a table. The viewer loads rows on demand and applies colu
 ## Persistent R Interactive
 
 This experimental feature provides native VS Code Interactive windows with independent plain-R or arf sessions, including adoption of existing arf sessions over Remote SSH. See the [setup and usage guide](https://github.com/REditorSupport/vscode-R/wiki/R-Interactive) for session switching, persistence, rich outputs, and platform requirements.
+
+## Icon attribution
+
+The list viewer’s navigation and chevron icons are from Microsoft’s [VS Code Codicons](https://github.com/microsoft/vscode-codicons), licensed under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). The icon artwork is unchanged.
diff --git a/images/icons/arrow-left.svg b/images/icons/arrow-left.svg
new file mode 100644
index 000000000..91773a7ec
--- /dev/null
+++ b/images/icons/arrow-left.svg
@@ -0,0 +1,3 @@
+
+
\ No newline at end of file
diff --git a/images/icons/chevron-down.svg b/images/icons/chevron-down.svg
new file mode 100644
index 000000000..389873c46
--- /dev/null
+++ b/images/icons/chevron-down.svg
@@ -0,0 +1,3 @@
+
+
\ No newline at end of file
diff --git a/images/icons/chevron-right.svg b/images/icons/chevron-right.svg
new file mode 100644
index 000000000..d08afa0b5
--- /dev/null
+++ b/images/icons/chevron-right.svg
@@ -0,0 +1,3 @@
+
+
\ No newline at end of file
diff --git a/sess/R/handlers.R b/sess/R/handlers.R
index f810dbc19..eb1a68755 100644
--- a/sess/R/handlers.R
+++ b/sess/R/handlers.R
@@ -133,16 +133,163 @@ workspace_child_label <- function(name, index) {
   }
 }
 
-handle_workspace_view <- function(name, path = list()) {
-  title <- paste0(c(name, vapply(path, function(selector) switch(selector$kind,
-    index = if (!is.null(selector$name) && !is.na(selector$name) && nzchar(selector$name)) paste0("$", selector$name) else paste0("[[", selector$value, "]]"),
-    name = paste0("$", selector$value),
-    slot = paste0("@", selector$value)
-  ), "")), collapse = "")
-  utils::View(workspace_object(name, path), title = title)
+# Keep one viewer of each type for a workspace root, including its descendants.
+workspace_show_view <- function(object, title, owner, context = NULL) {
+  previous <- .sess_env$view_owner
+  previous_context <- .sess_env$listview_context
+  on.exit({
+    .sess_env$view_owner <- previous
+    .sess_env$listview_context <- previous_context
+  }, add = TRUE)
+  .sess_env$view_owner <- owner
+  .sess_env$listview_context <- context
+  utils::View(object, title = title)
   TRUE
 }
 
+handle_workspace_view <- function(name, path = list()) {
+  suffix <- vapply(path, function(selector) {
+    switch(selector$kind,
+      index = {
+        if (!is.null(selector$name) && !is.na(selector$name) && nzchar(selector$name)) {
+          paste0("$", selector$name)
+        } else {
+          paste0("[[", selector$value, "]]")
+        }
+      },
+      name = paste0("$", selector$value),
+      slot = paste0("@", selector$value)
+    )
+  }, "")
+  title <- paste0(c(name, suffix), collapse = "")
+  root <- listview_state(workspace_object(name), name, name)
+  context <- listview_context(root, path)
+  workspace_show_view(workspace_object(name, path), title, name, context)
+}
+
+listview_is_list <- function(object) {
+  !dataview_is_table(object) &&
+    (is.list(object) || is.pairlist(object) || is.environment(object) || isS4(object))
+}
+
+listview_state <- function(object, title, owner) {
+  kind <- if (is.environment(object)) "name" else if (isS4(object)) "slot" else "index"
+  list(
+    type = "list", data = object, title = title, owner = owner, kind = kind,
+    names = switch(kind,
+      name = workspace_env_names(object),
+      slot = methods::slotNames(object),
+      index = names(object)
+    ),
+    child_names = new.env(parent = emptyenv())
+  )
+}
+
+# Resolve workspace selectors once; navigation paths are relative to the retained root.
+listview_context <- function(root, selectors) {
+  path <- list()
+  for (selector in selectors) {
+    location <- listview_location(root, path)
+    index <- if (selector$kind == "index" && is.numeric(selector$value)) {
+      selector$value
+    } else {
+      match(selector$value, location$names)
+    }
+    path <- c(path, list(index))
+  }
+  location <- listview_location(root, path)
+  list(root = root, navigation = list(
+    title = location$title, path = I(path), breadcrumbs = I(location$breadcrumbs)
+  ))
+}
+
+# Direct View(x$a) calls can also start with a complete breadcrumb path.
+listview_expression_context <- function(expression, envir, owner) {
+  tryCatch({
+    selectors <- list()
+    while (is.call(expression) && length(expression) == 3L &&
+             is.symbol(expression[[1L]])) {
+      operator <- as.character(expression[[1L]])
+      if (!operator %in% c("$", "[[", "@")) return(NULL)
+      value <- expression[[3L]]
+      if (operator %in% c("$", "@") && is.symbol(value)) value <- as.character(value)
+      if (length(value) != 1L || !(is.character(value) || is.numeric(value))) return(NULL)
+      selectors <- c(list(list(kind = "index", value = value)), selectors)
+      expression <- expression[[2L]]
+    }
+    if (!is.symbol(expression)) return(NULL)
+    name <- as.character(expression)
+    root <- listview_state(get(name, envir = envir, inherits = TRUE), name, owner)
+    listview_context(root, selectors)
+  }, error = function(e) NULL)
+}
+
+listview_navigation <- function(state, path = list()) {
+  location <- listview_location(state, path)
+  if (!listview_is_list(location$data) && length(path)) stop("Not a list view")
+  list(title = location$title, path = I(path), breadcrumbs = I(location$breadcrumbs))
+}
+
+handle_listview_navigate <- function(view_id, path = list()) {
+  state <- dataview_get_state(view_id)
+  if (!identical(state$type, "list")) stop("Not a list view")
+  listview_navigation(state, path)
+}
+
+listview_location <- function(state, path = list()) {
+  visited <- integer()
+  state$breadcrumbs <- list(list(label = state$title, path = I(list())))
+  for (index in path) {
+    child_count <- if (state$kind == "index") length(state$data) else length(state$names)
+    if (length(index) != 1L || !is.numeric(index) || is.na(index) ||
+          index != as.integer(index) || index < 1L || index > child_count) {
+      stop("Invalid list item index")
+    }
+    child_name <- if (is.null(state$names)) NULL else state$names[[index]]
+    if (state$kind == "name" &&
+          (!exists(child_name, envir = state$data, inherits = FALSE) ||
+             bindingIsActive(child_name, state$data))) {
+      stop("List item is unavailable")
+    }
+    child <- switch(state$kind,
+      name = get(child_name, envir = state$data, inherits = FALSE),
+      slot = methods::slot(state$data, child_name),
+      index = state$data[[index]]
+    )
+    state$title <- if (state$kind == "slot") {
+      paste0(state$title, "@", child_name)
+    } else if (!is.null(child_name) && !is.na(child_name) && nzchar(child_name)) {
+      paste0(state$title, "$", child_name)
+    } else {
+      paste0(state$title, "[[", index, "]]")
+    }
+    state$data <- child
+    state$kind <- if (is.environment(child)) "name" else if (isS4(child)) "slot" else "index"
+    state$names <- switch(state$kind,
+      name = workspace_env_names(child),
+      slot = methods::slotNames(child),
+      index = names(child)
+    )
+    visited <- c(visited, index)
+    label <- if (!is.null(child_name) && !is.na(child_name) && nzchar(child_name)) {
+      child_name
+    } else {
+      paste0("[[", index, "]]")
+    }
+    state$breadcrumbs <- c(state$breadcrumbs, list(list(label = label, path = I(as.list(visited)))))
+    # Environment bindings can disappear while their rows remain visible.
+    if (state$kind == "name" && is.environment(state$child_names)) {
+      key <- paste(visited, collapse = "/")
+      if (exists(key, envir = state$child_names, inherits = FALSE)) {
+        state$names <- get(key, envir = state$child_names, inherits = FALSE)
+      } else {
+        assign(key, state$names, envir = state$child_names)
+      }
+    }
+  }
+  state
+}
+
 get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_id = NULL) {
   tryCatch({
     if (is.null(view_id)) {
@@ -156,6 +303,7 @@ get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_
     } else {
       state <- dataview_get_state(view_id)
       if (!identical(state$type, "list")) stop("Not a list view")
+      state <- listview_location(state, path)
       object <- state$data
       kind <- state$kind
       child_names <- state$names
@@ -198,7 +346,10 @@ get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_
       )
       summary <- trimws(try_capture_str(child))
       if (!is.null(view_id)) {
-        list(label = label, str = summary, viewable = TRUE, index = index)
+        list(
+          label = label, str = summary, viewable = TRUE, index = index,
+          has_children = workspace_child_count(child) > 0L
+        )
       } else {
         selector <- if (kind == "index") {
           list(kind = kind, value = index, name = child_name)
@@ -215,36 +366,17 @@ get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_
   })
 }
 
-handle_listview_view <- function(view_id, index) {
+handle_listview_view <- function(view_id, index, path = list()) {
   state <- .sess_env$dataviews[[as.character(view_id)]]
   if (is.null(state) || !identical(state$type, "list")) {
     return(FALSE)
   }
-  index <- as.integer(index)
-  child_count <- if (state$kind == "index") length(state$data) else length(state$names)
-  if (length(index) != 1L || is.na(index) || index < 1L || index > child_count) {
-    return(FALSE)
+  location <- tryCatch(listview_location(state, c(path, list(index))), error = function(e) NULL)
+  if (is.null(location)) return(FALSE)
+  if (listview_is_list(location$data)) {
+    return(listview_navigation(state, c(path, list(index))))
   }
-  child_name <- if (is.null(state$names)) NULL else state$names[[index]]
-  if (state$kind == "name" &&
-        (!exists(child_name, envir = state$data, inherits = FALSE) ||
-           bindingIsActive(child_name, state$data))) {
-    return(FALSE)
-  }
-  child <- switch(state$kind,
-    name = get(child_name, envir = state$data, inherits = FALSE),
-    slot = methods::slot(state$data, child_name),
-    index = state$data[[index]]
-  )
-  title <- if (state$kind == "slot") {
-    paste0(state$title, "@", child_name)
-  } else if (!is.null(child_name) && !is.na(child_name) && nzchar(child_name)) {
-    paste0(state$title, "$", child_name)
-  } else {
-    paste0(state$title, "[[", index, "]]")
-  }
-  utils::View(child, title = title)
-  TRUE
+  workspace_show_view(location$data, location$title, state$owner %||% state$title)
 }
 
 handle_hover <- function(expr_str) {
diff --git a/sess/R/hooks.R b/sess/R/hooks.R
index ca395fd4a..d0f1e36ca 100644
--- a/sess/R/hooks.R
+++ b/sess/R/hooks.R
@@ -103,7 +103,17 @@ runtime_start <- function(use_rstudioapi = TRUE,
   }
 
   show_dataview <- function(x, title = deparse(substitute(x))) {
-    # make sure title is computed.
+    # Capture the root before forcing x so View(x$a) shares the viewer for x.
+    original_expression <- substitute(x)
+    expression <- original_expression
+    while (is.call(expression) && is.symbol(expression[[1L]]) &&
+             as.character(expression[[1L]]) %in% c("$", "[[", "@")) {
+      expression <- expression[[2L]]
+    }
+    owner <- .sess_env$view_owner
+    if (is.null(owner) && missing(title) && is.symbol(expression)) {
+      owner <- as.character(expression)
+    }
     force(title)
 
     if (isTRUE(.sess_env$interactive_connected) && .interactive_rich_value(x)) {
@@ -112,25 +122,24 @@ runtime_start <- function(use_rstudioapi = TRUE,
 
     view_type <- if (dataview_is_table(x)) {
       "table"
-    } else if (is.list(x) || is.environment(x) || isS4(x)) {
+    } else if (is.list(x) || is.pairlist(x) || is.environment(x) || isS4(x)) {
       "list"
     } else {
       "object"
     }
-    if (view_type != "object") {
-      title_key <- paste(as.character(title), collapse = "\n")
-      registry_key <- paste0(view_type, ":", title_key)
-      dataview_registry <- .sess_env$dataview_registry
-      view_id <- if (nzchar(title_key) &&
-                       exists(registry_key, envir = dataview_registry, inherits = FALSE)) {
-        get(registry_key, envir = dataview_registry, inherits = FALSE)
-      } else {
-        id <- dataview_new_id()
-        if (nzchar(title_key)) {
-          assign(registry_key, id, envir = dataview_registry)
-        }
-        id
+    title_key <- paste(as.character(title), collapse = "\n")
+    owner <- owner %||% title_key
+    registry_key <- paste0(view_type, ":", owner)
+    dataview_registry <- .sess_env$dataview_registry
+    view_id <- if (nzchar(title_key) &&
+                     exists(registry_key, envir = dataview_registry, inherits = FALSE)) {
+      get(registry_key, envir = dataview_registry, inherits = FALSE)
+    } else {
+      id <- dataview_new_id()
+      if (nzchar(title_key)) {
+        assign(registry_key, id, envir = dataview_registry)
       }
+      id
     }
 
     if (view_type == "table") {
@@ -143,29 +152,26 @@ runtime_start <- function(use_rstudioapi = TRUE,
         view_id = registration$view_id
       ))
     } else if (view_type == "list") {
-      child_kind <- if (is.environment(x)) "name" else if (isS4(x)) "slot" else "index"
-      x_names <- switch(child_kind,
-        name = workspace_env_names(x),
-        slot = methods::slotNames(x),
-        index = names(x)
-      )
-      .sess_env$dataviews[[view_id]] <- list(
-        type = "list",
-        data = x,
-        title = title_key,
-        kind = child_kind,
-        names = x_names
-      )
+      context <- .sess_env$listview_context
+      if (is.null(context) && missing(title)) {
+        context <- listview_expression_context(original_expression, parent.frame(), owner)
+      }
+      root <- if (is.null(context)) listview_state(x, title_key, owner) else context$root
+      navigation <- if (is.null(context)) listview_navigation(root) else context$navigation
+      .sess_env$dataviews[[view_id]] <- root
       notify_client("dataview", list(
         title = title,
         source = "list",
         type = "json",
-        view_id = view_id
+        view_id = view_id,
+        navigation = navigation
       ))
     } else {
       code <- if (is.primitive(x)) utils::capture.output(print(x)) else deparse(x)
-      file_path <- tempfile(tmpdir = .sess_env$tempdir, fileext = ".R")
+      file_path <- .sess_env$dataviews[[view_id]]$file %||%
+        tempfile(tmpdir = .sess_env$tempdir, fileext = ".R")
       writeLines(code, file_path)
+      .sess_env$dataviews[[view_id]] <- list(type = "object", file = file_path)
       notify_client("dataview", list(
         title = title,
         file = file_path,
diff --git a/sess/R/server.R b/sess/R/server.R
index f97bec091..6fb92ca9d 100644
--- a/sess/R/server.R
+++ b/sess/R/server.R
@@ -455,7 +455,8 @@ dispatch_message <- function(line) {
       "hover" = function(p) handle_hover(p$expr),
       "completion" = function(p) handle_complete(p$expr, p$trigger),
       "plot_latest" = function(p) handle_plot_latest(p),
-      "listview_view" = function(p) handle_listview_view(p$view_id, p$index),
+      "listview_navigate" = function(p) handle_listview_navigate(p$view_id, p$path),
+      "listview_view" = function(p) handle_listview_view(p$view_id, p$index, p$path),
       "dataview_init" = function(p) handle_dataview_init(p),
       "dataview_page" = function(p) handle_dataview_page(p),
       "dataview_dispose" = function(p) handle_dataview_dispose(p)
diff --git a/sess/inst/tinytest/test-ipc.R b/sess/inst/tinytest/test-ipc.R
index ef862e299..8ed00b95d 100644
--- a/sess/inst/tinytest/test-ipc.R
+++ b/sess/inst/tinytest/test-ipc.R
@@ -264,10 +264,10 @@ local({
   expect_false(identical(getHook("grid.newpage"), old_grid_hook))
 
   dataview_data <- data.frame(value = 1:2)
-  assign("lifecycle dataview", "runtime_view_before_restart",
+  assign("table:lifecycle dataview", "runtime_view_before_restart",
          envir = .sess_env$dataview_registry)
   utils::View(dataview_data, title = "lifecycle dataview")
-  first_view_id <- get("lifecycle dataview", envir = .sess_env$dataview_registry)
+  first_view_id <- get("table:lifecycle dataview", envir = .sess_env$dataview_registry)
   expect_identical(first_view_id, "runtime_view_before_restart")
   expect_true(first_view_id %in% names(.sess_env$dataviews))
 
@@ -284,7 +284,7 @@ local({
                length(grep("^sess.plot$", callbacks_after_first_start)))
 
   utils::View(dataview_data, title = "lifecycle dataview")
-  second_view_id <- get("lifecycle dataview", envir = .sess_env$dataview_registry)
+  second_view_id <- get("table:lifecycle dataview", envir = .sess_env$dataview_registry)
   expect_false(identical(first_view_id, second_view_id))
   expect_true(second_view_id %in% names(.sess_env$dataviews))
 
diff --git a/sess/inst/tinytest/test-listview.R b/sess/inst/tinytest/test-listview.R
new file mode 100644
index 000000000..867d5b0a2
--- /dev/null
+++ b/sess/inst/tinytest/test-listview.R
@@ -0,0 +1,172 @@
+# Expanding and opening descendants keeps one list/table viewer per root object.
+local({
+  runtime <- sess:::.sess_env
+  previous_con <- runtime$con
+  previous_views <- runtime$dataviews
+  previous_registry <- runtime$dataview_registry
+  root <- paste0(".sess_listview_test_", Sys.getpid())
+  other <- paste0(root, "_other")
+  pipe <- processx::conn_create_pipepair()
+  on.exit({
+    sess:::runtime_stop()
+    runtime$con <- previous_con
+    runtime$dataviews <- previous_views
+    runtime$dataview_registry <- previous_registry
+    rm(list = c(root, other), envir = .GlobalEnv)
+    lapply(pipe, close)
+  }, add = TRUE)
+  runtime$con <- pipe[[2L]]
+  sess:::runtime_start(use_rstudioapi = FALSE, use_httpgd = FALSE, use_jgd = FALSE)
+  x <- list(a = list(b = list(value = 1L), df = data.frame(nested = 2L)),
+            df = data.frame(top = 1L))
+  assign(root, x, envir = .GlobalEnv)
+  assign(other, x, envir = .GlobalEnv)
+
+  # Exercise the JSON-RPC methods used by both the workspace and list webviews.
+  request <- function(method, params) {
+    sess:::dispatch_message(as.character(jsonlite::toJSON(
+      list(jsonrpc = "2.0", id = "list-test", method = method, params = params),
+      auto_unbox = TRUE
+    )))
+    messages <- strsplit(processx::conn_read_chars(pipe[[1L]]), "\n", fixed = TRUE)[[1L]]
+    responses <- lapply(messages[nzchar(messages)], jsonlite::fromJSON, simplifyVector = FALSE)
+    replies <- Filter(function(message) identical(message$id, "list-test"), responses)
+    expect_length(replies, 1L)
+    expect_null(replies[[1L]]$error)
+    replies[[1L]]$result
+  }
+  id <- function(type, name = root) get(paste0(type, ":", name), runtime$dataview_registry)
+  selector <- function(index, name) list(kind = "index", value = index, name = name)
+
+  expect_true(request("workspace_view", list(name = root)))
+  list_id <- id("list")
+  page <- request("workspace_children", list(view_id = list_id, start = 1L))
+  expect_true(page$children[[1L]]$has_children)
+  expect_true(page$children[[1L]]$viewable)
+  expect_true(page$children[[2L]]$has_children)
+  expect_true(page$children[[2L]]$viewable)
+
+  nested <- request("workspace_children", list(view_id = list_id, path = list(1L), start = 1L))
+  expect_equal(vapply(nested$children, `[[`, "", "label"), c("$ b", "$ df"))
+  expect_identical(runtime$dataviews[[list_id]]$data, x)
+  expect_length(runtime$dataviews, 1L)
+  leaf <- request("workspace_children", list(view_id = list_id, path = list(1L, 1L), start = 1L))
+  expect_false(leaf$children[[1L]]$has_children)
+  expect_true(leaf$children[[1L]]$viewable)
+
+  # Open x$df, then x$a$df from an expanded row: the table id is unchanged.
+  expect_true(request("listview_view", list(view_id = list_id, index = 2L, path = list())))
+  table_id <- id("table")
+  expect_false(identical(table_id, list_id))
+  expect_true(request("listview_view", list(view_id = list_id, index = 2L, path = list(1L))))
+  expect_identical(id("table"), table_id)
+  columns <- sess:::handle_dataview_init(list(view_id = table_id))$columns
+  expect_equal(as.character(columns[[2L]]$headerName), "nested")
+
+  # The workspace icon and the list icon share the same root's panels.
+  expect_true(request("workspace_view", list(name = root, path = list(selector(1L, "a")))))
+  expect_identical(id("list"), list_id)
+  expect_identical(runtime$dataviews[[list_id]]$data, x)
+  navigation <- request("listview_view", list(view_id = list_id, index = 1L, path = list(1L)))
+  expect_equal(navigation$title, paste0(root, "$a$b"))
+  expect_equal(navigation$path, list(1L, 1L))
+  expect_equal(vapply(navigation$breadcrumbs, `[[`, "", "label"), c(root, "a", "b"))
+  expect_equal(navigation$breadcrumbs[[2L]]$path, list(1L))
+  expect_identical(id("list"), list_id)
+  expect_identical(runtime$dataviews[[list_id]]$data, x)
+  parent <- request("listview_navigate", list(view_id = list_id, path = list(1L)))
+  expect_equal(parent$title, paste0(root, "$a"))
+  back <- request("listview_navigate", list(view_id = list_id, path = list()))
+  expect_equal(back$title, root)
+  expect_equal(back$path, list())
+  expect_length(runtime$dataviews, 2L)
+  expect_true(request("workspace_view", list(name = root)))
+  expect_identical(id("list"), list_id)
+  expect_identical(runtime$dataviews[[list_id]]$data, x)
+
+  expect_true(request("workspace_view", list(name = other)))
+  expect_false(identical(id("list", other), list_id))
+  expect_true(request("workspace_view", list(name = other, path = list(selector(2L, "df")))))
+  expect_false(identical(id("table", other), table_id))
+
+  # Direct View calls also group nested expressions by their root.
+  utils::View(x)
+  direct_id <- id("list", "x")
+  utils::View(x$a)
+  expect_identical(id("list", "x"), direct_id)
+  expect_identical(runtime$dataviews[[direct_id]]$data, x)
+  utils::View(x$a$b)
+  expect_identical(runtime$dataviews[[direct_id]]$data, x)
+  direct_context <- sess:::listview_expression_context(quote(x$a$b), environment(), "x")
+  expect_equal(direct_context$navigation$path, list(1L, 1L), check.attributes = FALSE)
+  expect_equal(direct_context$navigation$title, "x$a$b")
+  utils::View(x$df)
+  direct_table <- id("table", "x")
+  utils::View(x$a$df)
+  expect_identical(id("table", "x"), direct_table)
+  utils::View(x$a$b$value)
+  text_id <- id("object", "x")
+  text_file <- runtime$dataviews[[text_id]]$file
+  utils::View(x$a$df$nested)
+  expect_identical(id("object", "x"), text_id)
+  expect_identical(runtime$dataviews[[text_id]]$file, text_file)
+  expect_equal(readLines(text_file), "2L")
+  unlink(text_file)
+
+  # Invalid or unavailable descendants cannot navigate or force active bindings.
+  expect_false(sess:::handle_listview_view(list_id, 0L))
+  expect_false(sess:::handle_listview_view(list_id, 1.5))
+  expect_false(sess:::handle_listview_view(list_id, 1L, list(99L)))
+  expect_true(sess:::handle_dataview_dispose(list(view_id = list_id)))
+  expect_null(runtime$dataviews[[list_id]])
+  sess:::handle_workspace_view(root)
+  expect_identical(id("list"), list_id)
+  expect_identical(runtime$dataviews[[list_id]]$data, x)
+})
+
+# Nested expansion pages retain lazy loading and handle environments, pairlists and slots.
+local({
+  runtime <- sess:::.sess_env
+  previous <- runtime$dataviews
+  on.exit(runtime$dataviews <- previous, add = TRUE)
+  env <- new.env(parent = emptyenv())
+  env$child <- pairlist(value = list(1L))
+  makeActiveBinding("active", function() stop("active binding evaluated"), env)
+  methods::setClass("list_viewer_nested_slots", slots = c(child = "list"))
+  on.exit(methods::removeClass("list_viewer_nested_slots"), add = TRUE)
+  object <- list(
+    many = rep(list(list(value = 1L)), 501L),
+    env = env,
+    slots = methods::new("list_viewer_nested_slots", child = list(value = 1L))
+  )
+  runtime$dataviews$nested_test <- list(
+    type = "list", data = object, kind = "index", names = names(object), title = "object",
+    child_names = new.env(parent = emptyenv())
+  )
+  page <- function(path, start = 1L) {
+    sess:::get_workspace_children(view_id = "nested_test", path = path, start = start)
+  }
+  first <- page(list(1L))
+  expect_length(first$children, 500L)
+  expect_equal(first$next_start, 501L)
+  last <- page(list(1L), 501L)
+  expect_length(last$children, 1L)
+  expect_equal(last$children[[1L]]$index, 501L)
+  expect_true(last$children[[1L]]$has_children)
+  expect_equal(page(list(1L, 501L))$children[[1L]]$label, "$ value")
+  env_page <- page(list(2L))
+  labels <- vapply(env_page$children, `[[`, "", "label")
+  active_index <- match("$ active", labels)
+  child_index <- match("$ child", labels)
+  expect_false(env_page$children[[active_index]]$viewable)
+  expect_false(sess:::handle_listview_view("nested_test", active_index, list(2L)))
+  expect_true(page(list(2L, child_index))$children[[1L]]$has_children)
+  rm("child", envir = env)
+  env$replacement <- list(value = 2L)
+  changed <- page(list(2L))
+  expect_equal(changed$children[[child_index]]$label, "$ child")
+  expect_false(changed$children[[child_index]]$viewable)
+  expect_false(sess:::handle_listview_view("nested_test", child_index, list(2L)))
+  expect_equal(page(list(3L))$children[[1L]]$label, "@ child")
+  expect_equal(page(list(3L, 1L))$children[[1L]]$label, "$ value")
+})
diff --git a/src/interactive/manager.ts b/src/interactive/manager.ts
index 3b9112265..199beddca 100644
--- a/src/interactive/manager.ts
+++ b/src/interactive/manager.ts
@@ -1184,7 +1184,7 @@ export class InteractiveManager implements vscode.Disposable, vscode.TreeDataPro
             switch (message.action) {
                 case 'table':
                     if (data.kind !== 'table') { return; }
-                    await session.showDataView('table', 'json', `${view.client.manifest.label}: ${data.fullViewId ? 'full table' : 'table'}`, '', 'Beside', String(data.fullViewId ?? data.viewId), view.target); break;
+                    await session.showDataView('table', 'json', `${view.client.manifest.label}: ${data.fullViewId ? 'full table' : 'table'}`, '', 'Beside', String(data.fullViewId ?? data.viewId), undefined, view.target); break;
                 case 'page': {
                     if (data.kind !== 'table') { return; }
                     result = await queryTablePage(data, message, request => view.client.request('inspect', request)); break;
diff --git a/src/listViewer.ts b/src/listViewer.ts
new file mode 100644
index 000000000..898f2377f
--- /dev/null
+++ b/src/listViewer.ts
@@ -0,0 +1,176 @@
+export interface ListViewNavigation {
+    title: string;
+    path: number[];
+    breadcrumbs: { label: string; path: number[] }[];
+}
+
+/** Script shared by the list webview and its interaction tests. */
+export function getListViewerScript(generation: number, initial: ListViewNavigation = {
+    title: '', path: [], breadcrumbs: [{ label: '', path: [] }],
+}): string {
+    return `
+    const vscode = acquireVsCodeApi();
+    const generation = ${generation};
+    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;
+
+    function showNavigation(navigation, goingBack = false) {
+        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);
+        }
+        current = navigation;
+        let page = pages.get(key);
+        if (!page) {
+            const element = document.createElement('div');
+            page = { element, scrollTop: 0, loader: createPage(element, navigation.path) };
+            pages.set(key, page);
+        }
+        list.replaceChildren(page.element);
+        list.scrollTop = page.scrollTop;
+        back.disabled = history.length === 0;
+        breadcrumbs.replaceChildren();
+        navigation.breadcrumbs.forEach((crumb, index) => {
+            if (index) {
+                const separator = document.createElement('span');
+                separator.className = 'breadcrumb-separator';
+                separator.setAttribute('aria-hidden', 'true');
+                breadcrumbs.appendChild(separator);
+            }
+            const isCurrent = index === navigation.breadcrumbs.length - 1;
+            const item = document.createElement(isCurrent ? 'span' : 'button');
+            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 }));
+            breadcrumbs.appendChild(item);
+        });
+        page.loader.loadOnce();
+    }
+
+    function navigate(message, params, goingBack = false) {
+        if (navigating) return;
+        navigating = true;
+        navigationStatus.textContent = '';
+        const requestId = ++nextRequestId;
+        pending.set(requestId, (response) => {
+            navigating = false;
+            if (response.error) {
+                navigationStatus.textContent = response.error;
+            } else if (response.navigation) {
+                showNavigation(response.navigation, goingBack);
+            }
+        });
+        vscode.postMessage({ message, generation, requestId, ...params });
+    }
+
+    back.addEventListener('click', () => {
+        if (history.length) navigate('listview/navigate', { path: history[history.length - 1].path }, true);
+    });
+
+    function createPage(container, path) {
+        const rows = document.createElement('div');
+        const more = document.createElement('button');
+        more.className = 'load-more';
+        more.textContent = 'Load more';
+        const status = document.createElement('div');
+        status.setAttribute('role', 'status');
+        container.appendChild(rows);
+        container.appendChild(more);
+        container.appendChild(status);
+        let nextStart = 1;
+        let loading = false;
+        let loaded = false;
+
+        function loadPage() {
+            if (loading || nextStart === null) return;
+            loading = true;
+            more.disabled = true;
+            more.textContent = 'Loading…';
+            status.textContent = '';
+            const requestId = ++nextRequestId;
+            pending.set(requestId, (message) => {
+                loading = false;
+                more.disabled = false;
+                if (message.error) {
+                    status.textContent = message.error;
+                    more.textContent = 'Retry';
+                    return;
+                }
+                loaded = true;
+                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');
+                    row.className = 'item';
+                    const arrow = document.createElement('span');
+                    arrow.className = 'arrow';
+                    arrow.setAttribute('aria-hidden', 'true');
+                    row.appendChild(arrow);
+                    const label = document.createElement('span');
+                    label.className = 'label';
+                    label.textContent = item.label;
+                    row.appendChild(label);
+                    const str = document.createElement('span');
+                    str.className = 'str';
+                    str.textContent = item.str;
+                    row.appendChild(str);
+
+                    if (item.viewable) {
+                        const button = document.createElement('button');
+                        button.title = 'View';
+                        button.setAttribute('aria-label', 'View ' + item.label);
+                        button.innerHTML = document.getElementById('view-icon').innerHTML;
+                        button.addEventListener('click', (event) => {
+                            event.preventDefault();
+                            event.stopPropagation();
+                            navigate('listview/view', { path, index: item.index });
+                        });
+                        row.appendChild(button);
+                    }
+                    entry.appendChild(row);
+                    if (expandable) {
+                        const children = document.createElement('div');
+                        children.className = 'children';
+                        entry.appendChild(children);
+                        const page = createPage(children, [...path, item.index]);
+                        entry.addEventListener('toggle', () => {
+                            if (entry.open) page.loadOnce();
+                        });
+                    }
+                    rows.appendChild(entry);
+                }
+                nextStart = message.next_start ?? null;
+                more.hidden = nextStart === null;
+                more.textContent = 'Load more';
+                status.textContent = rows.childElementCount ? '' : 'No items';
+            });
+            vscode.postMessage({ message: 'listview/page', generation, requestId, path, start: nextStart });
+        }
+        more.addEventListener('click', loadPage);
+        return { loadOnce: () => { if (!loaded) loadPage(); } };
+    }
+
+    window.addEventListener('message', (event) => {
+        const message = event.data;
+        if (!['listview/page', 'listview/navigation'].includes(message.message) || message.generation !== generation) return;
+        const receive = pending.get(message.requestId);
+        if (receive) {
+            pending.delete(message.requestId);
+            receive(message);
+        }
+    });
+    showNavigation(${JSON.stringify(initial).replace(/ {
+export async function showDataView(source: string, type: string, title: string, file: string, viewer: string, viewId?: string, navigation?: ListViewNavigation, owner = activeSession): Promise {
     resDir ??= path.join(extensionContext.extensionPath, 'dist', 'resources');
     console.info(`[showDataView] source: ${source}, type: ${type}, title: ${title}, file: ${file}, viewer: ${viewer}, viewId: ${String(viewId ?? '')}`);
 
@@ -1021,7 +1020,7 @@ export async function showDataView(source: string, type: string, title: string,
             const existing = dynamicDataViewPanels.get(`${owner?.sessionId ?? ''}:${viewId}`);
             if (existing) {
                 existing.title = title;
-                existing.reveal(ViewColumn[viewer as keyof typeof ViewColumn], true);
+                existing.reveal(existing.viewColumn, true);
                 const content = await getTableHtml(existing.webview, undefined, title);
                 existing.webview.html = `${content}\n`;
                 return;
@@ -1051,8 +1050,8 @@ export async function showDataView(source: string, type: string, title: string,
             const existing = dynamicDataViewPanels.get(viewId);
             if (existing) {
                 existing.title = title;
-                existing.reveal(ViewColumn[viewer as keyof typeof ViewColumn], true);
-                existing.webview.html = getListHtml(existing.webview, title);
+                existing.reveal(existing.viewColumn, true);
+                existing.webview.html = getListHtml(existing.webview, title, navigation);
                 return;
             }
         }
@@ -1071,20 +1070,40 @@ export async function showDataView(source: string, type: string, title: string,
         panel.iconPath = new UriIcon('open-preview');
         if (viewId) {
             dynamicDataViewPanels.set(viewId, panel);
-            panel.webview.onDidReceiveMessage(async (message: { message?: string; index?: number; start?: number; requestId?: number }) => {
-                if (message.message === 'listview/view' && typeof message.index === 'number' && Number.isInteger(message.index)) {
-                    void sessionRequest({
-                        method: 'listview_view',
-                        params: { view_id: viewId, index: message.index },
+            panel.webview.onDidReceiveMessage(async (message: {
+                message?: string; index?: number; start?: number; requestId?: number;
+                path?: number[]; generation?: number;
+            }) => {
+                if (!Array.isArray(message.path) || !message.path.every(index => Number.isSafeInteger(index) && index > 0)) {
+                    return;
+                }
+                if (message.message === 'listview/navigate' ||
+                    (message.message === 'listview/view' && Number.isSafeInteger(message.index))) {
+                    const result = await sessionRequest({
+                        method: message.message === 'listview/navigate' ? 'listview_navigate' : 'listview_view',
+                        params: { view_id: viewId, index: message.index, path: message.path },
+                    }) as ListViewNavigation | boolean | undefined;
+                    const navigation = result && typeof result === 'object' && Array.isArray(result.breadcrumbs)
+                        ? result : undefined;
+                    if (navigation) {
+                        panel.title = navigation.title;
+                    }
+                    void panel.webview.postMessage({
+                        message: 'listview/navigation',
+                        generation: message.generation,
+                        requestId: message.requestId,
+                        navigation,
+                        error: result ? undefined : 'Unable to open this item. Check the R session and try again.',
                     });
                 } else if (message.message === 'listview/page' && typeof message.start === 'number' &&
                     Number.isInteger(message.start) && typeof message.requestId === 'number') {
                     const page = await sessionRequest({
                         method: 'workspace_children',
-                        params: { view_id: viewId, start: message.start },
+                        params: { view_id: viewId, start: message.start, path: message.path },
                     }) as { children?: unknown; next_start?: number | null } | undefined;
                     void panel.webview.postMessage({
                         message: 'listview/page',
+                        generation: message.generation,
                         requestId: message.requestId,
                         ...page,
                         error: Array.isArray(page?.children) ? undefined : 'Unable to load items. Check the R session and try again.',
@@ -1101,7 +1120,7 @@ export async function showDataView(source: string, type: string, title: string,
                 });
             });
         }
-        panel.webview.html = getListHtml(panel.webview, title);
+        panel.webview.html = getListHtml(panel.webview, title, navigation);
     } else {
         await commands.executeCommand('vscode.open', Uri.file(file), {
             preserveFocus: true,
@@ -1804,10 +1823,19 @@ export async function getTableHtml(webview: Webview, file: string | undefined, t
 `;
 }
 
-export function getListHtml(webview: Webview, title: string): string {
+export function getListHtml(webview: Webview, title: string, navigation?: ListViewNavigation): string {
     const icon = new UriIcon('open-preview-codicon');
     const darkIcon = webview.asWebviewUri(icon.dark).toString();
     const lightIcon = webview.asWebviewUri(icon.light).toString();
+    const chevronIcon = webview.asWebviewUri(
+        Uri.file(extensionContext.asAbsolutePath('images/icons/chevron-right.svg'))
+    ).toString();
+    const backIcon = webview.asWebviewUri(
+        Uri.file(extensionContext.asAbsolutePath('images/icons/arrow-left.svg'))
+    ).toString();
+    const expandedChevronIcon = webview.asWebviewUri(
+        Uri.file(extensionContext.asAbsolutePath('images/icons/chevron-down.svg'))
+    ).toString();
 
     return `
 
@@ -1819,11 +1847,47 @@ export function getListHtml(webview: Webview, title: string): string {
     
 
 
+    

+        
+        
+    

+    
     

-    
-    

+    
     
 
 
@@ -2192,6 +2211,7 @@ async function handleNotification(message: Record, socket: IpcS
                         String(params.file ?? ''),
                         viewer,
                         params.view_id ? String(params.view_id) : undefined,
+                        params.navigation as ListViewNavigation | undefined,
                     );
                 }
             }
diff --git a/src/test/suite/listViewer.test.ts b/src/test/suite/listViewer.test.ts
new file mode 100644
index 000000000..93af77731
--- /dev/null
+++ b/src/test/suite/listViewer.test.ts
@@ -0,0 +1,213 @@
+import * as assert from 'assert';
+import * as vm from 'vm';
+import { getListViewerScript, ListViewNavigation } from '../../listViewer';
+
+// Minimal DOM surface for exercising the actual webview script and its RPCs.
+class Element {
+    children: Element[] = [];
+    listeners = new Map void>();
+    textContent = '';
+    innerHTML = '';
+    className = '';
+    hidden = false;
+    disabled = false;
+    open = false;
+    scrollTop = 0;
+    constructor(readonly tag: string) { }
+    get childElementCount(): number { return this.children.length; }
+    appendChild(child: Element): void { this.children.push(child); }
+    replaceChildren(...children: Element[]): void { this.children = children; }
+    setAttribute(): void { /* Attributes do not affect these interaction tests. */ }
+    addEventListener(type: string, listener: (event: unknown) => void): void {
+        this.listeners.set(type, listener);
+    }
+    fire(type: string, event: unknown = {}): void { this.listeners.get(type)?.(event); }
+}
+
+interface Request {
+    message: string;
+    generation: number;
+    requestId: number;
+    path: number[];
+    index?: number;
+    start?: number;
+}
+
+function createViewer(initial: ListViewNavigation = {
+    title: 'x', path: [], breadcrumbs: [{ label: 'x', path: [] }],
+}) {
+    const root = new Element('div');
+    const back = new Element('button');
+    const breadcrumbs = new Element('nav');
+    const status = new Element('div');
+    const elements: Record = { list: root, back, breadcrumbs, 'navigation-status': status };
+    const messages: Request[] = [];
+    let receive: (event: unknown) => void = () => undefined;
+    vm.runInNewContext(getListViewerScript(7, initial), {
+        acquireVsCodeApi: () => ({ postMessage: (message: Request) => {
+            messages.push(JSON.parse(JSON.stringify(message)) as Request);
+        } }),
+        document: {
+            createElement: (tag: string) => new Element(tag),
+            getElementById: (id: string) => elements[id] ?? new Element('template'),
+        },
+        window: { addEventListener: (_type: string, listener: typeof receive) => { receive = listener; } },
+    });
+    const reply = (request: Request, result: Record) => receive({
+        data: { ...request, children: [], next_start: null, ...result },
+    });
+    return { get root() { return root.children[0]; }, viewport: root, back, breadcrumbs, status, messages, reply };
+}
+
+suite('List viewer', () => {
+    test('Back restores expanded rows, loaded pages and scroll without fetching them again', () => {
+        const viewer = createViewer();
+        const { messages, reply, back, viewport } = viewer;
+        assert.strictEqual(back.disabled, true);
+        reply(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');
+        reply(messages[1], { children: [{ label: '$ b', index: 1, viewable: true, has_children: true }] });
+        viewport.scrollTop = 120;
+        const openButton = entry.children[0].children.at(-1);
+        assert.ok(openButton);
+        openButton.fire('click', { preventDefault: () => undefined, stopPropagation: () => undefined });
+        reply(messages[2], {
+            message: 'listview/navigation', navigation: {
+                title: 'x$a', path: [1], breadcrumbs: [{ label: 'x', path: [] }, { label: 'a', path: [1] }],
+            },
+        });
+        assert.strictEqual(back.disabled, false);
+        assert.deepStrictEqual(messages[3].path, [1]);
+        reply(messages[3], { children: [] });
+        back.fire('click');
+        assert.strictEqual(messages[4].message, 'listview/navigate');
+        assert.deepStrictEqual(messages[4].path, []);
+        reply(messages[4], {
+            message: 'listview/navigation', navigation: { title: 'x', path: [], breadcrumbs: [{ label: 'x', path: [] }] },
+        });
+        assert.strictEqual(viewer.root, original);
+        assert.strictEqual(entry.open, true);
+        assert.strictEqual(viewport.scrollTop, 120);
+        assert.strictEqual(messages.length, 5);
+        assert.strictEqual(back.disabled, true);
+    });
+
+    test('breadcrumbs work when opened directly at a deep item and Back follows page history', () => {
+        const initial = {
+            title: 'x$a$b', path: [1, 2], breadcrumbs: [
+                { label: 'x', path: [] }, { label: 'a', path: [1] }, { label: 'b', path: [1, 2] },
+            ],
+        };
+        const viewer = createViewer(initial);
+        assert.deepStrictEqual(viewer.messages[0].path, [1, 2]);
+        viewer.reply(viewer.messages[0], { children: [] });
+        const original = viewer.root;
+        assert.deepStrictEqual(viewer.breadcrumbs.children.map(item => item.className),
+            ['breadcrumb', 'breadcrumb-separator', 'breadcrumb', 'breadcrumb-separator', 'breadcrumb']);
+        viewer.breadcrumbs.children[0].fire('click');
+        assert.deepStrictEqual(viewer.messages[1].path, []);
+        viewer.reply(viewer.messages[1], {
+            message: 'listview/navigation', navigation: { title: 'x', path: [], breadcrumbs: [{ label: 'x', path: [] }] },
+        });
+        viewer.reply(viewer.messages[2], { children: [] });
+        viewer.back.fire('click');
+        assert.deepStrictEqual(viewer.messages[3].path, [1, 2]);
+        viewer.reply(viewer.messages[3], { message: 'listview/navigation', navigation: initial });
+        assert.strictEqual(viewer.root, original);
+    });
+
+    test('opening a table and failed navigation leave the list and its history intact', () => {
+        const viewer = createViewer();
+        viewer.reply(viewer.messages[0], { children: [{ label: '$ df', index: 1, viewable: true }] });
+        const original = viewer.root;
+        const button = original.children[0].children[0].children[0].children.at(-1);
+        assert.ok(button);
+        const click = { preventDefault: () => undefined, stopPropagation: () => undefined };
+        button.fire('click', click);
+        viewer.reply(viewer.messages[1], { message: 'listview/navigation' });
+        assert.strictEqual(viewer.root, original);
+        assert.strictEqual(viewer.back.disabled, true);
+        button.fire('click', click);
+        viewer.reply(viewer.messages[2], { message: 'listview/navigation', error: 'Item removed' });
+        assert.strictEqual(viewer.status.textContent, 'Item removed');
+        assert.strictEqual(viewer.root, original);
+        assert.strictEqual(viewer.back.disabled, true);
+    });
+
+    test('expands lazily, caches collapsed children, and opens descendants separately', () => {
+        const { root, messages, reply } = createViewer();
+        assert.deepStrictEqual(messages[0].path, []);
+        reply(messages[0], { children: [{ label: '$ a', str: 'List of 1', index: 1, viewable: true, has_children: true }] });
+        const entry = root.children[0].children[0];
+        assert.strictEqual(entry.tag, 'details');
+        assert.strictEqual(messages.length, 1);
+        entry.open = true;
+        entry.fire('toggle');
+        assert.deepStrictEqual(messages[1].path, [1]);
+        reply(messages[1], { children: [{ label: '$ b', str: 'List of 1', index: 2, viewable: true, has_children: true }] });
+        entry.open = false;
+        entry.fire('toggle');
+        entry.open = true;
+        entry.fire('toggle');
+        assert.strictEqual(messages.length, 2);
+
+        const nested = entry.children[1].children[0].children[0];
+        nested.open = true;
+        nested.fire('toggle');
+        assert.deepStrictEqual(messages[2].path, [1, 2]);
+        let prevented = false;
+        let stopped = false;
+        const openButton = nested.children[0].children.at(-1);
+        assert.ok(openButton);
+        openButton.fire('click', {
+            preventDefault: () => { prevented = true; },
+            stopPropagation: () => { stopped = true; },
+        });
+        assert.ok(prevented && stopped);
+        assert.strictEqual(messages[3].message, 'listview/view');
+        assert.deepStrictEqual(messages[3].path, [1]);
+        assert.strictEqual(messages[3].index, 2);
+    });
+
+    test('routes concurrent expansion pages, retries failures, and paginates each branch', () => {
+        const { root, messages, reply } = createViewer();
+        reply(messages[0], { children: [1, 2].map(index => ({ index, label: String(index), has_children: true })) });
+        const [first, second] = root.children[0].children;
+        first.open = second.open = true;
+        first.fire('toggle');
+        second.fire('toggle');
+        reply(messages[2], { children: [{ label: 'second', index: 1 }], next_start: 501 });
+        reply(messages[1], { error: 'Temporarily unavailable' });
+        const firstPage = first.children[1];
+        const secondPage = second.children[1];
+        assert.strictEqual(firstPage.children[2].textContent, 'Temporarily unavailable');
+        assert.strictEqual(secondPage.children[0].childElementCount, 1);
+        firstPage.children[1].fire('click');
+        assert.deepStrictEqual(messages[3].path, [1]);
+        reply(messages[3], { children: [] });
+        assert.strictEqual(firstPage.children[2].textContent, 'No items');
+        secondPage.children[1].fire('click');
+        assert.deepStrictEqual(messages[4].path, [2]);
+        assert.strictEqual(messages[4].start, 501);
+        reply(messages[4], { children: [{ label: 'last', index: 501 }] });
+        assert.strictEqual(secondPage.children[0].childElementCount, 2);
+        assert.strictEqual(secondPage.children[1].hidden, true);
+    });
+
+    test('ignores old viewer responses and hides open buttons for unavailable items', () => {
+        const { root, messages, reply } = createViewer();
+        reply(messages[0], { generation: 6, children: [{ label: 'stale' }] });
+        assert.strictEqual(root.children[0].childElementCount, 0);
+        reply(messages[0], { children: [
+            { label: 'removed', viewable: false },
+            { label: 'scalar', index: 2, viewable: true, has_children: false },
+        ] });
+        const [removed, scalar] = root.children[0].children;
+        assert.ok(!removed.children[0].children.some(child => child.tag === 'button'));
+        assert.ok(scalar.children[0].children.some(child => child.tag === 'button'));
+        assert.strictEqual(scalar.tag, 'div');
+    });
+});
diff --git a/src/test/suite/listViewerPanels.test.ts b/src/test/suite/listViewerPanels.test.ts
new file mode 100644
index 000000000..868e35578
--- /dev/null
+++ b/src/test/suite/listViewerPanels.test.ts
@@ -0,0 +1,79 @@
+import * as assert from 'assert';
+import * as path from 'path';
+import * as sinon from 'sinon';
+import * as vscode from 'vscode';
+import { mockExtensionContext } from '../common/mockvscode';
+import * as session from '../../session';
+import { GlobalEnvItem } from '../../workspaceViewer';
+
+suite('List viewer panels', () => {
+    let sandbox: sinon.SinonSandbox;
+    const panels: vscode.WebviewPanel[] = [];
+
+    setup(() => {
+        sandbox = sinon.createSandbox();
+        const root = path.join(__dirname, '..', '..', '..');
+        mockExtensionContext(root, sandbox);
+        session.deploySessionWatcher(root);
+    });
+
+    teardown(() => {
+        panels.splice(0).forEach(panel => { panel.dispose(); });
+        sandbox.restore();
+    });
+
+    test('reuses separate list and table panels, updates titles, and reopens closed viewers', async () => {
+        const reveals: sinon.SinonStub[] = [];
+        const create = sandbox.stub(vscode.window, 'createWebviewPanel').callsFake((_type, title) => {
+            const disposed = new vscode.EventEmitter();
+            const reveal = sandbox.stub();
+            reveals.push(reveal);
+            const panel = {
+                title, viewColumn: vscode.ViewColumn.Three,
+                reveal,
+                webview: {
+                    html: '', asWebviewUri: (uri: vscode.Uri) => uri,
+                    onDidReceiveMessage: sandbox.stub(),
+                },
+                onDidDispose: disposed.event,
+                dispose: () => { disposed.fire(); disposed.dispose(); },
+            } as unknown as vscode.WebviewPanel;
+            panels.push(panel);
+            return panel;
+        });
+
+        await session.showDataView('list', 'json', 'x', '', 'Two', 'test-list-x');
+        await session.showDataView('list', 'json', 'x$a', '', 'Two', 'test-list-x');
+        await session.showDataView('list', 'json', 'x$a$b', '', 'Two', 'test-list-x');
+        sinon.assert.calledOnce(create);
+        assert.strictEqual(panels[0].title, 'x$a$b');
+        sinon.assert.alwaysCalledWithExactly(reveals[0], vscode.ViewColumn.Three, true);
+
+        await session.showDataView('table', 'json', 'x$df', '', 'Two', 'test-table-x');
+        await session.showDataView('table', 'json', 'x$a$df', '', 'Two', 'test-table-x');
+        assert.strictEqual(create.callCount, 2);
+        assert.strictEqual(panels[1].title, 'x$a$df');
+        assert.strictEqual(panels[0].title, 'x$a$b');
+        await session.showDataView('list', 'json', 'y', '', 'Two', 'test-list-y');
+        assert.strictEqual(create.callCount, 3);
+        const first = panels.shift();
+        assert.ok(first);
+        first.dispose();
+        await session.showDataView('list', 'json', 'x', '', 'Two', 'test-list-x');
+        assert.strictEqual(create.callCount, 4);
+    });
+
+    test('supported workspace children retain open actions alongside expansion', () => {
+        for (const type of ['list', 'environment', 'pairlist', 'S4', 'double', 'closure']) {
+            const structured = ['list', 'environment', 'pairlist', 'S4'].includes(type);
+            const node = new GlobalEnvItem('', type, '$ item', type, 1, undefined, structured,
+                'x', [{ kind: 'index', value: 1 }], true);
+            assert.strictEqual(node.contextValue, 'viewableNode');
+            assert.strictEqual(node.collapsibleState, structured
+                ? vscode.TreeItemCollapsibleState.Collapsed : vscode.TreeItemCollapsibleState.None);
+        }
+        const unavailable = new GlobalEnvItem('', 'active_binding', '', 'active_binding', 1,
+            undefined, false, 'x', [], false);
+        assert.notStrictEqual(unavailable.contextValue, 'viewableNode');
+    });
+});

From c242a633d160ca0c68448fd121f7f5b773be8402 Mon Sep 17 00:00:00 2001
From: Fred-Wu <4111978+Fred-Wu@users.noreply.github.com>
Date: Sat, 3 Oct 2026 20:23:08 +1000
Subject: [PATCH 08/30] Fix nested viewer routing and icons

---
 sess/R/handlers.R                       |  8 ++++++++
 sess/inst/tinytest/test-listview.R      | 21 ++++++++++++++++++++-
 src/session.ts                          |  2 +-
 src/test/suite/listViewerPanels.test.ts |  6 ++++++
 4 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/sess/R/handlers.R b/sess/R/handlers.R
index eb1a68755..9fb4f9935 100644
--- a/sess/R/handlers.R
+++ b/sess/R/handlers.R
@@ -233,6 +233,14 @@ listview_navigation <- function(state, path = list()) {
 handle_listview_navigate <- function(view_id, path = list()) {
   state <- dataview_get_state(view_id)
   if (!identical(state$type, "list")) stop("Not a list view")
+  location <- listview_location(state, path)
+  if (dataview_is_table(location$data)) {
+    return(workspace_show_view(
+      location$data,
+      location$title,
+      state$owner %||% state$title
+    ))
+  }
   listview_navigation(state, path)
 }
 
diff --git a/sess/inst/tinytest/test-listview.R b/sess/inst/tinytest/test-listview.R
index 867d5b0a2..78ada573b 100644
--- a/sess/inst/tinytest/test-listview.R
+++ b/sess/inst/tinytest/test-listview.R
@@ -6,13 +6,14 @@ local({
   previous_registry <- runtime$dataview_registry
   root <- paste0(".sess_listview_test_", Sys.getpid())
   other <- paste0(root, "_other")
+  table_root <- paste0(root, "_table")
   pipe <- processx::conn_create_pipepair()
   on.exit({
     sess:::runtime_stop()
     runtime$con <- previous_con
     runtime$dataviews <- previous_views
     runtime$dataview_registry <- previous_registry
-    rm(list = c(root, other), envir = .GlobalEnv)
+    rm(list = c(root, other, table_root), envir = .GlobalEnv)
     lapply(pipe, close)
   }, add = TRUE)
   runtime$con <- pipe[[2L]]
@@ -89,6 +90,24 @@ local({
   expect_true(request("workspace_view", list(name = other, path = list(selector(2L, "df")))))
   expect_false(identical(id("table", other), table_id))
 
+  # A list column can use the List Viewer without changing the table root's viewer.
+  table_object <- data.frame(id = 1:2)
+  table_object$nested <- I(list(list(value = 1L), list(value = 2L)))
+  assign(table_root, table_object, envir = .GlobalEnv)
+  expect_true(request("workspace_view", list(name = table_root)))
+  root_table_id <- id("table", table_root)
+  expect_true(request("workspace_view", list(
+    name = table_root,
+    path = list(selector(2L, "nested"))
+  )))
+  table_list_id <- id("list", table_root)
+  expect_false(identical(table_list_id, root_table_id))
+  expect_true(request("listview_navigate", list(
+    view_id = table_list_id,
+    path = list()
+  )))
+  expect_identical(id("table", table_root), root_table_id)
+
   # Direct View calls also group nested expressions by their root.
   utils::View(x)
   direct_id <- id("list", "x")
diff --git a/src/session.ts b/src/session.ts
index e1ed9e878..9625b32f4 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -1067,7 +1067,7 @@ export async function showDataView(source: string, type: string, title: string,
                 retainContextWhenHidden: true,
                 localResourceRoots: [Uri.file(extensionContext.asAbsolutePath('images/icons'))],
             });
-        panel.iconPath = new UriIcon('open-preview');
+        panel.iconPath = new UriIcon('preview');
         if (viewId) {
             dynamicDataViewPanels.set(viewId, panel);
             panel.webview.onDidReceiveMessage(async (message: {
diff --git a/src/test/suite/listViewerPanels.test.ts b/src/test/suite/listViewerPanels.test.ts
index 868e35578..fa23aeee8 100644
--- a/src/test/suite/listViewerPanels.test.ts
+++ b/src/test/suite/listViewerPanels.test.ts
@@ -47,12 +47,18 @@ suite('List viewer panels', () => {
         await session.showDataView('list', 'json', 'x$a$b', '', 'Two', 'test-list-x');
         sinon.assert.calledOnce(create);
         assert.strictEqual(panels[0].title, 'x$a$b');
+        const listIcon = panels[0].iconPath as { dark: vscode.Uri; light: vscode.Uri };
+        assert.strictEqual(path.basename(listIcon.dark.fsPath), 'preview.svg');
+        assert.strictEqual(path.basename(listIcon.light.fsPath), 'preview.svg');
         sinon.assert.alwaysCalledWithExactly(reveals[0], vscode.ViewColumn.Three, true);
 
         await session.showDataView('table', 'json', 'x$df', '', 'Two', 'test-table-x');
         await session.showDataView('table', 'json', 'x$a$df', '', 'Two', 'test-table-x');
         assert.strictEqual(create.callCount, 2);
         assert.strictEqual(panels[1].title, 'x$a$df');
+        const tableIcon = panels[1].iconPath as { dark: vscode.Uri; light: vscode.Uri };
+        assert.strictEqual(path.basename(tableIcon.dark.fsPath), 'open-preview.svg');
+        assert.strictEqual(path.basename(tableIcon.light.fsPath), 'open-preview.svg');
         assert.strictEqual(panels[0].title, 'x$a$b');
         await session.showDataView('list', 'json', 'y', '', 'Two', 'test-list-y');
         assert.strictEqual(create.callCount, 3);

From 3d0dee0ab7a44be662690a337d2ac36a35dcf062 Mon Sep 17 00:00:00 2001
From: Fred-Wu <4111978+Fred-Wu@users.noreply.github.com>
Date: Sat, 3 Oct 2026 20:48:00 +1000
Subject: [PATCH 09/30] Page vector values in viewer

---
 sess/R/handlers.R                       | 42 ++++++++++++++++++++-----
 sess/R/hooks.R                          |  7 +++--
 sess/inst/tinytest/test-listview.R      | 31 ++++++++++++++++++
 src/listViewer.ts                       | 13 +++++---
 src/session.ts                          | 29 ++++++++++++-----
 src/test/suite/listViewer.test.ts       | 19 +++++++++--
 src/test/suite/listViewerPanels.test.ts |  4 ++-
 7 files changed, 121 insertions(+), 24 deletions(-)

diff --git a/sess/R/handlers.R b/sess/R/handlers.R
index 9fb4f9935..0eb2dca94 100644
--- a/sess/R/handlers.R
+++ b/sess/R/handlers.R
@@ -232,7 +232,7 @@ listview_navigation <- function(state, path = list()) {
 
 handle_listview_navigate <- function(view_id, path = list()) {
   state <- dataview_get_state(view_id)
-  if (!identical(state$type, "list")) stop("Not a list view")
+  if (!state$type %in% c("list", "vector")) stop("Not a list view")
   location <- listview_location(state, path)
   if (dataview_is_table(location$data)) {
     return(workspace_show_view(
@@ -241,6 +241,15 @@ handle_listview_navigate <- function(view_id, path = list()) {
       state$owner %||% state$title
     ))
   }
+  if (identical(state$type, "vector") && listview_is_list(location$data)) {
+    navigation <- listview_navigation(state, path)
+    return(workspace_show_view(
+      location$data,
+      location$title,
+      state$owner %||% state$title,
+      list(root = state, navigation = navigation)
+    ))
+  }
   listview_navigation(state, path)
 }
 
@@ -310,13 +319,22 @@ get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_
       )
     } else {
       state <- dataview_get_state(view_id)
-      if (!identical(state$type, "list")) stop("Not a list view")
+      if (!state$type %in% c("list", "vector")) stop("Not a list view")
+      vector_view <- identical(state$type, "vector")
       state <- listview_location(state, path)
       object <- state$data
       kind <- state$kind
       child_names <- state$names
     }
-    child_count <- if (kind == "index") workspace_child_count(object) else length(child_names)
+    child_count <- if (kind == "index") {
+      if (!is.null(view_id) && isTRUE(vector_view)) {
+        length(object)
+      } else {
+        workspace_child_count(object)
+      }
+    } else {
+      length(child_names)
+    }
     start <- max(1L, as.integer(start))
     end <- min(child_count, start + workspace_child_page_size - 1L)
     if (start > end) {
@@ -325,7 +343,9 @@ get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_
 
     children <- lapply(seq.int(start, end), function(index) {
       child_name <- if (is.null(child_names)) NULL else child_names[[index]]
-      label <- if (kind == "slot") {
+      label <- if (!is.null(view_id) && isTRUE(vector_view)) {
+        paste0("[", index, "]")
+      } else if (kind == "slot") {
         paste0("@ ", child_name)
       } else {
         workspace_child_label(child_name, index)
@@ -352,11 +372,19 @@ get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_
         slot = methods::slot(object, child_name),
         index = object[[index]]
       )
-      summary <- trimws(try_capture_str(child))
+      summary <- if (!is.null(view_id) && isTRUE(vector_view)) {
+        if (is.character(child)) {
+          encodeString(child, quote = "\"", na.encode = TRUE)
+        } else {
+          paste(format(child, trim = TRUE), collapse = " ")
+        }
+      } else {
+        trimws(try_capture_str(child))
+      }
       if (!is.null(view_id)) {
         list(
-          label = label, str = summary, viewable = TRUE, index = index,
-          has_children = workspace_child_count(child) > 0L
+          label = label, str = summary, viewable = !isTRUE(vector_view), index = index,
+          has_children = !isTRUE(vector_view) && workspace_child_count(child) > 0L
         )
       } else {
         selector <- if (kind == "index") {
diff --git a/sess/R/hooks.R b/sess/R/hooks.R
index d0f1e36ca..699321634 100644
--- a/sess/R/hooks.R
+++ b/sess/R/hooks.R
@@ -124,6 +124,8 @@ runtime_start <- function(use_rstudioapi = TRUE,
       "table"
     } else if (is.list(x) || is.pairlist(x) || is.environment(x) || isS4(x)) {
       "list"
+    } else if (is.atomic(x) && length(x) > 1L) {
+      "vector"
     } else {
       "object"
     }
@@ -151,17 +153,18 @@ runtime_start <- function(use_rstudioapi = TRUE,
         type = "json",
         view_id = registration$view_id
       ))
-    } else if (view_type == "list") {
+    } else if (view_type %in% c("list", "vector")) {
       context <- .sess_env$listview_context
       if (is.null(context) && missing(title)) {
         context <- listview_expression_context(original_expression, parent.frame(), owner)
       }
       root <- if (is.null(context)) listview_state(x, title_key, owner) else context$root
+      root$type <- view_type
       navigation <- if (is.null(context)) listview_navigation(root) else context$navigation
       .sess_env$dataviews[[view_id]] <- root
       notify_client("dataview", list(
         title = title,
-        source = "list",
+        source = view_type,
         type = "json",
         view_id = view_id,
         navigation = navigation
diff --git a/sess/inst/tinytest/test-listview.R b/sess/inst/tinytest/test-listview.R
index 78ada573b..4a82dc864 100644
--- a/sess/inst/tinytest/test-listview.R
+++ b/sess/inst/tinytest/test-listview.R
@@ -96,6 +96,21 @@ local({
   assign(table_root, table_object, envir = .GlobalEnv)
   expect_true(request("workspace_view", list(name = table_root)))
   root_table_id <- id("table", table_root)
+  expect_true(request("workspace_view", list(
+    name = table_root,
+    path = list(selector(1L, "id"))
+  )))
+  vector_id <- id("vector", table_root)
+  expect_false(identical(vector_id, root_table_id))
+  vector_page <- request("workspace_children", list(
+    view_id = vector_id,
+    path = list(1L),
+    start = 1L
+  ))
+  expect_equal(vapply(vector_page$children, `[[`, "", "label"), c("[1]", "[2]"))
+  expect_equal(vapply(vector_page$children, `[[`, "", "str"), c("1", "2"))
+  expect_false(any(vapply(vector_page$children, `[[`, FALSE, "viewable")))
+  expect_false(any(vapply(vector_page$children, `[[`, FALSE, "has_children")))
   expect_true(request("workspace_view", list(
     name = table_root,
     path = list(selector(2L, "nested"))
@@ -123,6 +138,22 @@ local({
   direct_table <- id("table", "x")
   utils::View(x$a$df)
   expect_identical(id("table", "x"), direct_table)
+  utils::View(seq_len(501L))
+  direct_vector <- id("vector", "seq_len(501L)")
+  first_vector_page <- sess:::get_workspace_children(
+    view_id = direct_vector,
+    start = 1L
+  )
+  expect_length(first_vector_page$children, 500L)
+  expect_equal(first_vector_page$next_start, 501L)
+  last_vector_page <- sess:::get_workspace_children(
+    view_id = direct_vector,
+    start = 501L
+  )
+  expect_length(last_vector_page$children, 1L)
+  expect_equal(last_vector_page$children[[1L]]$label, "[501]")
+  expect_equal(last_vector_page$children[[1L]]$str, "501")
+
   utils::View(x$a$b$value)
   text_id <- id("object", "x")
   text_file <- runtime$dataviews[[text_id]]$file
diff --git a/src/listViewer.ts b/src/listViewer.ts
index 898f2377f..addff67d3 100644
--- a/src/listViewer.ts
+++ b/src/listViewer.ts
@@ -7,10 +7,11 @@ export interface ListViewNavigation {
 /** Script shared by the list webview and its interaction tests. */
 export function getListViewerScript(generation: number, initial: ListViewNavigation = {
     title: '', path: [], breadcrumbs: [{ label: '', path: [] }],
-}): string {
+}, vector = false): string {
     return `
     const vscode = acquireVsCodeApi();
     const generation = ${generation};
+    const vector = ${vector};
     const pending = new Map();
     let nextRequestId = 0;
     const list = document.getElementById('list');
@@ -114,10 +115,12 @@ export function getListViewerScript(generation: number, initial: ListViewNavigat
                     const entry = document.createElement(expandable ? 'details' : 'div');
                     const row = document.createElement(expandable ? 'summary' : 'div');
                     row.className = 'item';
-                    const arrow = document.createElement('span');
-                    arrow.className = 'arrow';
-                    arrow.setAttribute('aria-hidden', 'true');
-                    row.appendChild(arrow);
+                    if (!vector) {
+                        const arrow = document.createElement('span');
+                        arrow.className = 'arrow';
+                        arrow.setAttribute('aria-hidden', 'true');
+                        row.appendChild(arrow);
+                    }
                     const label = document.createElement('span');
                     label.className = 'label';
                     label.textContent = item.label;
diff --git a/src/session.ts b/src/session.ts
index 9625b32f4..7b793c7c7 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -1045,13 +1045,15 @@ export async function showDataView(source: string, type: string, title: string,
         }
         const content = await getTableHtml(panel.webview, file || undefined, title);
         panel.webview.html = content;
-    } else if (source === 'list') {
+    } else if (source === 'list' || source === 'vector') {
         if (viewId) {
             const existing = dynamicDataViewPanels.get(viewId);
             if (existing) {
                 existing.title = title;
                 existing.reveal(existing.viewColumn, true);
-                existing.webview.html = getListHtml(existing.webview, title, navigation);
+                existing.webview.html = getListHtml(
+                    existing.webview, title, navigation, source === 'vector'
+                );
                 return;
             }
         }
@@ -1120,7 +1122,9 @@ export async function showDataView(source: string, type: string, title: string,
                 });
             });
         }
-        panel.webview.html = getListHtml(panel.webview, title, navigation);
+        panel.webview.html = getListHtml(
+            panel.webview, title, navigation, source === 'vector'
+        );
     } else {
         await commands.executeCommand('vscode.open', Uri.file(file), {
             preserveFocus: true,
@@ -1823,7 +1827,12 @@ export async function getTableHtml(webview: Webview, file: string | undefined, t
 `;
 }
 
-export function getListHtml(webview: Webview, title: string, navigation?: ListViewNavigation): string {
+export function getListHtml(
+    webview: Webview,
+    title: string,
+    navigation?: ListViewNavigation,
+    vector = false
+): string {
     const icon = new UriIcon('open-preview-codicon');
     const darkIcon = webview.asWebviewUri(icon.dark).toString();
     const lightIcon = webview.asWebviewUri(icon.light).toString();
@@ -1914,6 +1923,12 @@ export function getListHtml(webview: Webview, title: string, navigation?: ListVi
         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);
@@ -1953,10 +1968,10 @@ export function getListHtml(webview: Webview, title: string, navigation?: ListVi
     }
     
 
-
+
     

         
-        
+        
     

     
     

@@ -1964,7 +1979,7 @@ export function getListHtml(webview: Webview, title: string, navigation?: ListVi
     
 
 
diff --git a/src/test/suite/listViewer.test.ts b/src/test/suite/listViewer.test.ts
index 93af77731..5bf6d47e8 100644
--- a/src/test/suite/listViewer.test.ts
+++ b/src/test/suite/listViewer.test.ts
@@ -35,7 +35,7 @@ interface Request {
 
 function createViewer(initial: ListViewNavigation = {
     title: 'x', path: [], breadcrumbs: [{ label: 'x', path: [] }],
-}) {
+}, vector = false) {
     const root = new Element('div');
     const back = new Element('button');
     const breadcrumbs = new Element('nav');
@@ -43,7 +43,7 @@ function createViewer(initial: ListViewNavigation = {
     const elements: Record = { list: root, back, breadcrumbs, 'navigation-status': status };
     const messages: Request[] = [];
     let receive: (event: unknown) => void = () => undefined;
-    vm.runInNewContext(getListViewerScript(7, initial), {
+    vm.runInNewContext(getListViewerScript(7, initial, vector), {
         acquireVsCodeApi: () => ({ postMessage: (message: Request) => {
             messages.push(JSON.parse(JSON.stringify(message)) as Request);
         } }),
@@ -197,6 +197,21 @@ suite('List viewer', () => {
         assert.strictEqual(secondPage.children[1].hidden, true);
     });
 
+    test('renders vector values as simple indexed rows', () => {
+        const viewer = createViewer(undefined, true);
+        viewer.reply(viewer.messages[0], {
+            children: [{
+                label: '[1]', str: '12.4', index: 1,
+                viewable: false, has_children: false,
+            }],
+        });
+        const row = viewer.root.children[0].children[0].children[0];
+        assert.deepStrictEqual(row.children.map(child => child.className), ['label', 'str']);
+        assert.strictEqual(row.children[0].textContent, '[1]');
+        assert.strictEqual(row.children[1].textContent, '12.4');
+        assert.ok(!row.children.some(child => child.tag === 'button'));
+    });
+
     test('ignores old viewer responses and hides open buttons for unavailable items', () => {
         const { root, messages, reply } = createViewer();
         reply(messages[0], { generation: 6, children: [{ label: 'stale' }] });
diff --git a/src/test/suite/listViewerPanels.test.ts b/src/test/suite/listViewerPanels.test.ts
index fa23aeee8..418f009c6 100644
--- a/src/test/suite/listViewerPanels.test.ts
+++ b/src/test/suite/listViewerPanels.test.ts
@@ -62,11 +62,13 @@ suite('List viewer panels', () => {
         assert.strictEqual(panels[0].title, 'x$a$b');
         await session.showDataView('list', 'json', 'y', '', 'Two', 'test-list-y');
         assert.strictEqual(create.callCount, 3);
+        await session.showDataView('vector', 'json', 'x$id', '', 'Two', 'test-vector-x');
+        assert.strictEqual(create.callCount, 4);
         const first = panels.shift();
         assert.ok(first);
         first.dispose();
         await session.showDataView('list', 'json', 'x', '', 'Two', 'test-list-x');
-        assert.strictEqual(create.callCount, 4);
+        assert.strictEqual(create.callCount, 5);
     });
 
     test('supported workspace children retain open actions alongside expansion', () => {

From 4aee993b4cb8795b3135758fc788489b57c3e018 Mon Sep 17 00:00:00 2001
From: "4111978+Fred-Wu@users.noreply.github.com"
 <4111978+Fred-Wu@users.noreply.github.com>
Date: Sat, 3 Oct 2026 21:21:46 +1000
Subject: [PATCH 10/30] Fix lint error

---
 src/listViewer.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/listViewer.ts b/src/listViewer.ts
index addff67d3..7f0be625a 100644
--- a/src/listViewer.ts
+++ b/src/listViewer.ts
@@ -11,7 +11,7 @@ export function getListViewerScript(generation: number, initial: ListViewNavigat
     return `
     const vscode = acquireVsCodeApi();
     const generation = ${generation};
-    const vector = ${vector};
+    const vector = ${String(vector)};
     const pending = new Map();
     let nextRequestId = 0;
     const list = document.getElementById('list');

From 98511f4a13c5d58c7fc487c65448510365d919cd Mon Sep 17 00:00:00 2001
From: "4111978+Fred-Wu@users.noreply.github.com"
 <4111978+Fred-Wu@users.noreply.github.com>
Date: Sun, 4 Oct 2026 12:19:52 +1100
Subject: [PATCH 11/30] fix(viewer): unify list and vector navigation

- Reuse one list viewer panel and identity per root object
- Preserve breadcrumbs, Back history, and cached pages for vectors
- Render POSIXlt values without recursive expansion
- Ignore stale requests and replies after panel reuse
- Resolve workspace paths once and reuse environment-name snapshots
- Create child page controls only when expanded
- Remove unused jQuery and JSON viewer dependencies and assets
- Add regression tests for navigation, reuse, and lazy loading
---
 esbuild.js                              |   3 -
 package.json                            |   2 -
 pnpm-lock.yaml                          |  16 ---
 sess/R/handlers.R                       | 127 ++++++++++------------
 sess/R/hooks.R                          |  13 ++-
 sess/inst/tinytest/test-listview.R      | 139 +++++++++++++++++++++++-
 src/listViewer.ts                       |  17 ++-
 src/session.ts                          |  35 ++++--
 src/test/suite/listViewer.test.ts       |  70 +++++++++++-
 src/test/suite/listViewerPanels.test.ts |  48 +++++++-
 10 files changed, 346 insertions(+), 124 deletions(-)

diff --git a/esbuild.js b/esbuild.js
index 1ab93a298..29df03330 100644
--- a/esbuild.js
+++ b/esbuild.js
@@ -10,9 +10,6 @@ function copyResources() {
     fs.mkdirSync(destDir, { recursive: true });
 
     const resources = [
-        './node_modules/jquery/dist/jquery.min.js',
-        './node_modules/jquery.json-viewer/json-viewer/jquery.json-viewer.js',
-        './node_modules/jquery.json-viewer/json-viewer/jquery.json-viewer.css',
         './node_modules/ag-grid-community/dist/ag-grid-community.min.noStyle.js',
         './node_modules/ag-grid-community/styles/ag-grid.min.css',
         './node_modules/ag-grid-community/styles/ag-theme-balham.min.css'
diff --git a/package.json b/package.json
index b247feced..b7ea83415 100644
--- a/package.json
+++ b/package.json
@@ -2573,8 +2573,6 @@
     "fs-extra": "^10.1.0",
     "highlight.js": "^11.11.1",
     "httpgd": "0.1.6",
-    "jquery": "^3.7.1",
-    "jquery.json-viewer": "^1.5.0",
     "js-yaml": "^4.3.2",
     "node-fetch": "^2.7.0",
     "vscode-languageclient": "^9.0.1",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index e6a235f9d..a9078eafa 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -29,12 +29,6 @@ importers:
       httpgd:
         specifier: 0.1.6
         version: 0.1.6
-      jquery:
-        specifier: ^3.7.1
-        version: 3.7.1
-      jquery.json-viewer:
-        specifier: ^1.5.0
-        version: 1.5.0
       js-yaml:
         specifier: ^4.3.2
         version: 4.3.2
@@ -1728,12 +1722,6 @@ packages:
     engines: {node: '>=10'}
     hasBin: true
 
-  jquery.json-viewer@1.5.0:
-    resolution: {integrity: sha512-M/mRFXg14V/UUAlz7TBNBIDmQdWt05BunsqC/UjEx5BoFdQpNpfkfDdVn+VtjX951n/an/T9GWB3apBp02x8Mg==}
-
-  jquery@3.7.1:
-    resolution: {integrity: sha512-m4avr8yL8kmFN8psrbFFFmB/If14iN5o9nw/NgnnM+kybDJpRsAynV2BsfpTYrTRysYUdADVD7CkUUizgkpLfg==}
-
   js-tokens@4.0.0:
     resolution: {integrity: sha512-RdJUflcE3cUzKiMqQgsCu06FPu9UdIJO0beYbPhHN4k6apgJtifcoCtT9bcxOpYBtpD2kCM6Sbzg4CausW/PKQ==}
 
@@ -4327,10 +4315,6 @@ snapshots:
       filelist: 1.0.6
       picocolors: 1.1.1
 
-  jquery.json-viewer@1.5.0: {}
-
-  jquery@3.7.1: {}
-
   js-tokens@4.0.0: {}
 
   js-yaml@3.15.2:
diff --git a/sess/R/handlers.R b/sess/R/handlers.R
index 0eb2dca94..e506d788b 100644
--- a/sess/R/handlers.R
+++ b/sess/R/handlers.R
@@ -22,7 +22,10 @@ workspace_env_names <- function(env) {
 }
 
 workspace_child_count <- function(object) {
-  if (is.environment(object)) {
+  # POSIXlt is list-backed, but [[ returns another date-time, not a child list.
+  if (inherits(object, "POSIXlt")) {
+    0L
+  } else if (is.environment(object)) {
     length(workspace_env_names(object))
   } else if (isS4(object)) {
     length(methods::slotNames(object))
@@ -148,28 +151,21 @@ workspace_show_view <- function(object, title, owner, context = NULL) {
 }
 
 handle_workspace_view <- function(name, path = list()) {
-  suffix <- vapply(path, function(selector) {
-    switch(selector$kind,
-      index = {
-        if (!is.null(selector$name) && !is.na(selector$name) && nzchar(selector$name)) {
-          paste0("$", selector$name)
-        } else {
-          paste0("[[", selector$value, "]]")
-        }
-      },
-      name = paste0("$", selector$value),
-      slot = paste0("@", selector$value)
-    )
-  }, "")
-  title <- paste0(c(name, suffix), collapse = "")
   root <- listview_state(workspace_object(name), name, name)
   context <- listview_context(root, path)
-  workspace_show_view(workspace_object(name, path), title, name, context)
+  workspace_show_view(context$data, context$navigation$title, name, context)
+}
+
+# Lists and vectors share one viewer; only their row presentation differs.
+listview_supported <- function(object) {
+  !dataview_is_table(object) &&
+    (is.list(object) || is.pairlist(object) || is.environment(object) || isS4(object) ||
+       (is.atomic(object) && length(object) > 1L))
 }
 
-listview_is_list <- function(object) {
+listview_is_vector <- function(object) {
   !dataview_is_table(object) &&
-    (is.list(object) || is.pairlist(object) || is.environment(object) || isS4(object))
+    (inherits(object, "POSIXlt") || (!isS4(object) && is.atomic(object) && length(object) > 1L))
 }
 
 listview_state <- function(object, title, owner) {
@@ -187,20 +183,8 @@ listview_state <- function(object, title, owner) {
 
 # Resolve workspace selectors once; navigation paths are relative to the retained root.
 listview_context <- function(root, selectors) {
-  path <- list()
-  for (selector in selectors) {
-    location <- listview_location(root, path)
-    index <- if (selector$kind == "index" && is.numeric(selector$value)) {
-      selector$value
-    } else {
-      match(selector$value, location$names)
-    }
-    path <- c(path, list(index))
-  }
-  location <- listview_location(root, path)
-  list(root = root, navigation = list(
-    title = location$title, path = I(path), breadcrumbs = I(location$breadcrumbs)
-  ))
+  location <- listview_location(root, selectors, resolve_selectors = TRUE)
+  list(root = root, data = location$data, navigation = listview_navigation(location))
 }
 
 # Direct View(x$a) calls can also start with a complete breadcrumb path.
@@ -224,15 +208,16 @@ listview_expression_context <- function(expression, envir, owner) {
   }, error = function(e) NULL)
 }
 
-listview_navigation <- function(state, path = list()) {
-  location <- listview_location(state, path)
-  if (!listview_is_list(location$data) && length(path)) stop("Not a list view")
-  list(title = location$title, path = I(path), breadcrumbs = I(location$breadcrumbs))
+listview_navigation <- function(location) {
+  list(
+    title = location$title, path = I(location$path), breadcrumbs = I(location$breadcrumbs),
+    vector = listview_is_vector(location$data)
+  )
 }
 
 handle_listview_navigate <- function(view_id, path = list()) {
   state <- dataview_get_state(view_id)
-  if (!state$type %in% c("list", "vector")) stop("Not a list view")
+  if (!identical(state$type, "list")) stop("Not a list view")
   location <- listview_location(state, path)
   if (dataview_is_table(location$data)) {
     return(workspace_show_view(
@@ -241,22 +226,21 @@ handle_listview_navigate <- function(view_id, path = list()) {
       state$owner %||% state$title
     ))
   }
-  if (identical(state$type, "vector") && listview_is_list(location$data)) {
-    navigation <- listview_navigation(state, path)
-    return(workspace_show_view(
-      location$data,
-      location$title,
-      state$owner %||% state$title,
-      list(root = state, navigation = navigation)
-    ))
-  }
-  listview_navigation(state, path)
+  if (!listview_supported(location$data)) stop("Not a list view")
+  listview_navigation(location)
 }
 
-listview_location <- function(state, path = list()) {
+listview_location <- function(state, path = list(), resolve_selectors = FALSE) {
   visited <- integer()
   state$breadcrumbs <- list(list(label = state$title, path = I(list())))
   for (index in path) {
+    if (resolve_selectors) {
+      index <- if (index$kind == "index" && is.numeric(index$value)) {
+        index$value
+      } else {
+        match(index$value, state$names)
+      }
+    }
     child_count <- if (state$kind == "index") length(state$data) else length(state$names)
     if (length(index) != 1L || !is.numeric(index) || is.na(index) ||
           index != as.integer(index) || index < 1L || index > child_count) {
@@ -282,33 +266,37 @@ listview_location <- function(state, path = list()) {
     }
     state$data <- child
     state$kind <- if (is.environment(child)) "name" else if (isS4(child)) "slot" else "index"
+    visited <- c(visited, index)
     state$names <- switch(state$kind,
-      name = workspace_env_names(child),
+      name = {
+        # Reuse the binding snapshot without enumerating the environment again.
+        key <- paste(visited, collapse = "/")
+        if (is.environment(state$child_names) &&
+              exists(key, envir = state$child_names, inherits = FALSE)) {
+          get(key, envir = state$child_names, inherits = FALSE)
+        } else {
+          child_names <- workspace_env_names(child)
+          if (is.environment(state$child_names)) assign(key, child_names, envir = state$child_names)
+          child_names
+        }
+      },
       slot = methods::slotNames(child),
       index = names(child)
     )
-    visited <- c(visited, index)
     label <- if (!is.null(child_name) && !is.na(child_name) && nzchar(child_name)) {
       child_name
     } else {
       paste0("[[", index, "]]")
     }
     state$breadcrumbs <- c(state$breadcrumbs, list(list(label = label, path = I(as.list(visited)))))
-    # Environment bindings can disappear while their rows remain visible.
-    if (state$kind == "name" && is.environment(state$child_names)) {
-      key <- paste(visited, collapse = "/")
-      if (exists(key, envir = state$child_names, inherits = FALSE)) {
-        state$names <- get(key, envir = state$child_names, inherits = FALSE)
-      } else {
-        assign(key, state$names, envir = state$child_names)
-      }
-    }
   }
+  state$path <- as.list(visited)
   state
 }
 
 get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_id = NULL) {
   tryCatch({
+    vector_rows <- FALSE
     if (is.null(view_id)) {
       object <- workspace_object(name, path)
       kind <- if (is.environment(object)) "name" else if (isS4(object)) "slot" else "index"
@@ -319,15 +307,15 @@ get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_
       )
     } else {
       state <- dataview_get_state(view_id)
-      if (!state$type %in% c("list", "vector")) stop("Not a list view")
-      vector_view <- identical(state$type, "vector")
+      if (!identical(state$type, "list")) stop("Not a list view")
       state <- listview_location(state, path)
       object <- state$data
+      vector_rows <- listview_is_vector(object)
       kind <- state$kind
       child_names <- state$names
     }
     child_count <- if (kind == "index") {
-      if (!is.null(view_id) && isTRUE(vector_view)) {
+      if (vector_rows) {
         length(object)
       } else {
         workspace_child_count(object)
@@ -343,7 +331,7 @@ get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_
 
     children <- lapply(seq.int(start, end), function(index) {
       child_name <- if (is.null(child_names)) NULL else child_names[[index]]
-      label <- if (!is.null(view_id) && isTRUE(vector_view)) {
+      label <- if (vector_rows) {
         paste0("[", index, "]")
       } else if (kind == "slot") {
         paste0("@ ", child_name)
@@ -372,7 +360,7 @@ get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_
         slot = methods::slot(object, child_name),
         index = object[[index]]
       )
-      summary <- if (!is.null(view_id) && isTRUE(vector_view)) {
+      summary <- if (vector_rows) {
         if (is.character(child)) {
           encodeString(child, quote = "\"", na.encode = TRUE)
         } else {
@@ -383,8 +371,8 @@ get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_
       }
       if (!is.null(view_id)) {
         list(
-          label = label, str = summary, viewable = !isTRUE(vector_view), index = index,
-          has_children = !isTRUE(vector_view) && workspace_child_count(child) > 0L
+          label = label, str = summary, viewable = !vector_rows, index = index,
+          has_children = !vector_rows && workspace_child_count(child) > 0L
         )
       } else {
         selector <- if (kind == "index") {
@@ -407,10 +395,11 @@ handle_listview_view <- function(view_id, index, path = list()) {
   if (is.null(state) || !identical(state$type, "list")) {
     return(FALSE)
   }
-  location <- tryCatch(listview_location(state, c(path, list(index))), error = function(e) NULL)
+  path <- c(path, list(index))
+  location <- tryCatch(listview_location(state, path), error = function(e) NULL)
   if (is.null(location)) return(FALSE)
-  if (listview_is_list(location$data)) {
-    return(listview_navigation(state, c(path, list(index))))
+  if (listview_supported(location$data)) {
+    return(listview_navigation(location))
   }
   workspace_show_view(location$data, location$title, state$owner %||% state$title)
 }
diff --git a/sess/R/hooks.R b/sess/R/hooks.R
index 699321634..45ea5533c 100644
--- a/sess/R/hooks.R
+++ b/sess/R/hooks.R
@@ -122,10 +122,8 @@ runtime_start <- function(use_rstudioapi = TRUE,
 
     view_type <- if (dataview_is_table(x)) {
       "table"
-    } else if (is.list(x) || is.pairlist(x) || is.environment(x) || isS4(x)) {
+    } else if (listview_supported(x)) {
       "list"
-    } else if (is.atomic(x) && length(x) > 1L) {
-      "vector"
     } else {
       "object"
     }
@@ -153,14 +151,17 @@ runtime_start <- function(use_rstudioapi = TRUE,
         type = "json",
         view_id = registration$view_id
       ))
-    } else if (view_type %in% c("list", "vector")) {
+    } else if (view_type == "list") {
       context <- .sess_env$listview_context
       if (is.null(context) && missing(title)) {
         context <- listview_expression_context(original_expression, parent.frame(), owner)
       }
       root <- if (is.null(context)) listview_state(x, title_key, owner) else context$root
-      root$type <- view_type
-      navigation <- if (is.null(context)) listview_navigation(root) else context$navigation
+      navigation <- if (is.null(context)) {
+        listview_navigation(listview_location(root))
+      } else {
+        context$navigation
+      }
       .sess_env$dataviews[[view_id]] <- root
       notify_client("dataview", list(
         title = title,
diff --git a/sess/inst/tinytest/test-listview.R b/sess/inst/tinytest/test-listview.R
index 4a82dc864..d41db1eb9 100644
--- a/sess/inst/tinytest/test-listview.R
+++ b/sess/inst/tinytest/test-listview.R
@@ -24,13 +24,22 @@ local({
   assign(other, x, envir = .GlobalEnv)
 
   # Exercise the JSON-RPC methods used by both the workspace and list webviews.
+  notifications <- list()
+  read_messages <- function() {
+    messages <- strsplit(processx::conn_read_chars(pipe[[1L]]), "\n", fixed = TRUE)[[1L]]
+    responses <- lapply(messages[nzchar(messages)], jsonlite::fromJSON, simplifyVector = FALSE)
+    notifications <<- Filter(function(message) identical(message$method, "dataview"), responses)
+    responses
+  }
+  notification <- function() {
+    if (length(notifications)) tail(notifications, 1L)[[1L]]$params else NULL
+  }
   request <- function(method, params) {
     sess:::dispatch_message(as.character(jsonlite::toJSON(
       list(jsonrpc = "2.0", id = "list-test", method = method, params = params),
       auto_unbox = TRUE
     )))
-    messages <- strsplit(processx::conn_read_chars(pipe[[1L]]), "\n", fixed = TRUE)[[1L]]
-    responses <- lapply(messages[nzchar(messages)], jsonlite::fromJSON, simplifyVector = FALSE)
+    responses <- read_messages()
     replies <- Filter(function(message) identical(message$id, "list-test"), responses)
     expect_length(replies, 1L)
     expect_null(replies[[1L]]$error)
@@ -100,7 +109,8 @@ local({
     name = table_root,
     path = list(selector(1L, "id"))
   )))
-  vector_id <- id("vector", table_root)
+  vector_id <- id("list", table_root)
+  expect_true(notification()$navigation$vector)
   expect_false(identical(vector_id, root_table_id))
   vector_page <- request("workspace_children", list(
     view_id = vector_id,
@@ -116,6 +126,8 @@ local({
     path = list(selector(2L, "nested"))
   )))
   table_list_id <- id("list", table_root)
+  expect_identical(table_list_id, vector_id)
+  expect_false(notification()$navigation$vector)
   expect_false(identical(table_list_id, root_table_id))
   expect_true(request("listview_navigate", list(
     view_id = table_list_id,
@@ -139,7 +151,7 @@ local({
   utils::View(x$a$df)
   expect_identical(id("table", "x"), direct_table)
   utils::View(seq_len(501L))
-  direct_vector <- id("vector", "seq_len(501L)")
+  direct_vector <- id("list", "seq_len(501L)")
   first_vector_page <- sess:::get_workspace_children(
     view_id = direct_vector,
     start = 1L
@@ -163,6 +175,84 @@ local({
   expect_equal(readLines(text_file), "2L")
   unlink(text_file)
 
+  # Vectors opened from expanded list rows retain the root and every breadcrumb.
+  values <- list(nested = list(v = seq_len(501L)))
+  assign(other, values, envir = .GlobalEnv)
+  expect_true(request("workspace_view", list(name = other)))
+  values_list_id <- id("list", other)
+  vector_navigation <- request("listview_view", list(
+    view_id = values_list_id, path = list(1L), index = 1L
+  ))
+  expect_length(notifications, 0L)
+  expect_true(vector_navigation$vector)
+  expect_equal(vector_navigation$path, list(1L, 1L))
+  expect_equal(vapply(vector_navigation$breadcrumbs, `[[`, "", "label"),
+               c(other, "nested", "v"))
+  expect_identical(runtime$dataviews[[values_list_id]]$data, values)
+  first <- sess:::get_workspace_children(view_id = values_list_id, path = list(1L, 1L))
+  expect_length(first$children, 500L)
+  expect_equal(first$next_start, 501L)
+  last <- request("workspace_children", list(
+    view_id = values_list_id, path = list(1L, 1L), start = 501L
+  ))
+  expect_equal(vapply(last$children, `[[`, "", "str"), "501")
+  parent <- request("listview_navigate", list(view_id = values_list_id, path = list(1L)))
+  expect_length(notifications, 0L)
+  expect_false(parent$vector)
+  expect_equal(parent$path, list(1L))
+  back <- request("listview_navigate", list(view_id = values_list_id, path = list(1L, 1L)))
+  expect_equal(back, vector_navigation)
+  expect_true(request("workspace_view", list(
+    name = other, path = list(selector(1L, "nested"), selector(1L, "v"))
+  )))
+  expect_equal(notification()$view_id, values_list_id)
+  expect_equal(notification()$source, "list")
+  expect_equal(notification()$navigation, vector_navigation)
+  utils::View(values)
+  direct_values_id <- id("list", "values")
+  utils::View(values$nested$v)
+  read_messages()
+  expect_equal(notification()$view_id, direct_values_id)
+  expect_true(notification()$navigation$vector)
+  expect_equal(notification()$navigation$path, list(1L, 1L))
+  expect_equal(vapply(notification()$navigation$breadcrumbs, `[[`, "", "label"),
+               c("values", "nested", "v"))
+
+  # POSIXlt values are vector leaves, including scalar, missing and empty values.
+  dates <- as.POSIXlt(c("2026-01-01 12:34:56", "2026-01-02 01:02:03", NA), tz = "UTC")
+  for (sample in list(dates, dates[1L], dates[3L], dates[FALSE])) {
+    utils::View(sample, title = "POSIXlt values")
+    read_messages()
+    expect_equal(notification()$source, "list")
+    expect_true(notification()$navigation$vector)
+    page <- request("workspace_children", list(view_id = notification()$view_id))
+    expect_length(page$children, length(sample))
+    expected <- format(sample, "%Y-%m-%d %H:%M:%S")
+    expected[is.na(expected)] <- "NA"
+    expect_equal(vapply(page$children, `[[`, "", "str"), expected)
+    expect_false(any(vapply(page$children, `[[`, FALSE, "has_children")))
+    expect_false(any(vapply(page$children, `[[`, FALSE, "viewable")))
+    expect_equal(sess:::workspace_child_count(sample), 0L)
+  }
+  values <- list(dates = dates)
+  assign(other, values, envir = .GlobalEnv)
+  expect_true(request("workspace_view", list(name = other)))
+  page <- request("workspace_children", list(name = other))
+  expect_false(page$children[[1L]]$has_children)
+  expect_true(page$children[[1L]]$viewable)
+  page <- request("workspace_children", list(view_id = values_list_id))
+  expect_false(page$children[[1L]]$has_children)
+  expect_true(page$children[[1L]]$viewable)
+  navigation <- request("listview_view", list(view_id = values_list_id, index = 1L))
+  expect_length(notifications, 0L)
+  expect_true(navigation$vector)
+  expect_equal(navigation$path, list(1L))
+  expect_true(request("workspace_view", list(name = other, path = list(selector(1L, "dates")))))
+  expect_equal(notification()$source, "list")
+  expect_equal(notification()$view_id, values_list_id)
+  expect_equal(notification()$navigation, navigation)
+  expect_false(any(startsWith(ls(runtime$dataview_registry), "vector:")))
+
   # Invalid or unavailable descendants cannot navigate or force active bindings.
   expect_false(sess:::handle_listview_view(list_id, 0L))
   expect_false(sess:::handle_listview_view(list_id, 1.5))
@@ -220,3 +310,44 @@ local({
   expect_equal(page(list(3L))$children[[1L]]$label, "@ child")
   expect_equal(page(list(3L, 1L))$children[[1L]]$label, "$ value")
 })
+
+# Resolve a deep selector path once rather than repeatedly extracting its prefixes.
+local({
+  class_name <- paste0("sess_counted_list_", Sys.getpid())
+  method_name <- paste0("[[.", class_name)
+  extractions <- 0L
+  assign(method_name, function(object, index, ...) {
+    extractions <<- extractions + 1L
+    unclass(object)[[index]]
+  }, envir = .GlobalEnv)
+  on.exit(rm(list = method_name, envir = .GlobalEnv), add = TRUE)
+  object <- 1:3
+  for (i in seq_len(6L)) object <- structure(list(child = object), class = class_name)
+  root <- sess:::listview_state(object, "object", "object")
+  selectors <- rep(list(list(kind = "index", value = 1L)), 6L)
+  context <- sess:::listview_context(root, selectors)
+  expect_equal(extractions, 6L)
+  expect_identical(context$data, 1:3)
+  expect_equal(context$navigation$path, rep(list(1L), 6L), check.attributes = FALSE)
+  expect_equal(context$navigation$title, paste0("object", paste(rep("$child", 6L), collapse = "")))
+})
+
+# Repeated pages use cached environment names without enumerating bindings again.
+local({
+  scans <- 0L
+  location <- sess:::listview_location
+  environment(location) <- new.env(parent = environment(location))
+  environment(location)$workspace_env_names <- function(object) {
+    scans <<- scans + 1L
+    sess:::workspace_env_names(object)
+  }
+  child <- new.env(parent = emptyenv())
+  child$value <- 1:3
+  root <- sess:::listview_state(list(child = child), "object", "object")
+  first <- location(root, list(1L))
+  expect_equal(scans, 1L)
+  child$added <- 4:6
+  again <- location(root, list(1L))
+  expect_equal(scans, 1L)
+  expect_identical(again$names, first$names)
+})
diff --git a/src/listViewer.ts b/src/listViewer.ts
index 7f0be625a..34d8526d2 100644
--- a/src/listViewer.ts
+++ b/src/listViewer.ts
@@ -2,16 +2,17 @@ export interface ListViewNavigation {
     title: string;
     path: number[];
     breadcrumbs: { label: string; path: number[] }[];
+    /** Row presentation at this path; lists and vectors share the same viewer. */
+    vector?: boolean;
 }
 
 /** Script shared by the list webview and its interaction tests. */
 export function getListViewerScript(generation: number, initial: ListViewNavigation = {
     title: '', path: [], breadcrumbs: [{ label: '', path: [] }],
-}, vector = false): string {
+}): string {
     return `
     const vscode = acquireVsCodeApi();
     const generation = ${generation};
-    const vector = ${String(vector)};
     const pending = new Map();
     let nextRequestId = 0;
     const list = document.getElementById('list');
@@ -31,10 +32,11 @@ export function getListViewerScript(generation: number, initial: ListViewNavigat
             else if (JSON.stringify(current.path) !== key) history.push(current);
         }
         current = navigation;
+        document.body.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) };
+            page = { element, scrollTop: 0, loader: createPage(element, navigation.path, navigation.vector) };
             pages.set(key, page);
         }
         list.replaceChildren(page.element);
@@ -80,7 +82,7 @@ export function getListViewerScript(generation: number, initial: ListViewNavigat
         if (history.length) navigate('listview/navigate', { path: history[history.length - 1].path }, true);
     });
 
-    function createPage(container, path) {
+    function createPage(container, path, vector = false) {
         const rows = document.createElement('div');
         const more = document.createElement('button');
         more.className = 'load-more';
@@ -147,9 +149,12 @@ export function getListViewerScript(generation: number, initial: ListViewNavigat
                         const children = document.createElement('div');
                         children.className = 'children';
                         entry.appendChild(children);
-                        const page = createPage(children, [...path, item.index]);
+                        let page;
                         entry.addEventListener('toggle', () => {
-                            if (entry.open) page.loadOnce();
+                            if (entry.open) {
+                                page ??= createPage(children, [...path, item.index]);
+                                page.loadOnce();
+                            }
                         });
                     }
                     rows.appendChild(entry);
diff --git a/src/session.ts b/src/session.ts
index 7b793c7c7..58072c8b8 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -220,6 +220,7 @@ interface DataViewRequestMessage {
 }
 
 const dynamicDataViewPanels = new Map();
+const listViewGenerations = new WeakMap();
 let dynamicDataViewReloadRevision = 0;
 
 function escapeHtml(text: string): string {
@@ -1045,14 +1046,14 @@ export async function showDataView(source: string, type: string, title: string,
         }
         const content = await getTableHtml(panel.webview, file || undefined, title);
         panel.webview.html = content;
-    } else if (source === 'list' || source === 'vector') {
+    } else if (source === 'list') {
         if (viewId) {
             const existing = dynamicDataViewPanels.get(viewId);
             if (existing) {
                 existing.title = title;
                 existing.reveal(existing.viewColumn, true);
                 existing.webview.html = getListHtml(
-                    existing.webview, title, navigation, source === 'vector'
+                    existing.webview, title, navigation
                 );
                 return;
             }
@@ -1076,6 +1077,9 @@ export async function showDataView(source: string, type: string, title: string,
                 message?: string; index?: number; start?: number; requestId?: number;
                 path?: number[]; generation?: number;
             }) => {
+                if (message.generation !== listViewGenerations.get(panel.webview)) {
+                    return;
+                }
                 if (!Array.isArray(message.path) || !message.path.every(index => Number.isSafeInteger(index) && index > 0)) {
                     return;
                 }
@@ -1085,6 +1089,9 @@ export async function showDataView(source: string, type: string, title: string,
                         method: message.message === 'listview/navigate' ? 'listview_navigate' : 'listview_view',
                         params: { view_id: viewId, index: message.index, path: message.path },
                     }) as ListViewNavigation | boolean | undefined;
+                    if (message.generation !== listViewGenerations.get(panel.webview)) {
+                        return;
+                    }
                     const navigation = result && typeof result === 'object' && Array.isArray(result.breadcrumbs)
                         ? result : undefined;
                     if (navigation) {
@@ -1103,6 +1110,9 @@ export async function showDataView(source: string, type: string, title: string,
                         method: 'workspace_children',
                         params: { view_id: viewId, start: message.start, path: message.path },
                     }) as { children?: unknown; next_start?: number | null } | undefined;
+                    if (message.generation !== listViewGenerations.get(panel.webview)) {
+                        return;
+                    }
                     void panel.webview.postMessage({
                         message: 'listview/page',
                         generation: message.generation,
@@ -1113,9 +1123,11 @@ export async function showDataView(source: string, type: string, title: string,
                 }
             });
             panel.onDidDispose(() => {
-                if (dynamicDataViewPanels.get(viewId) === panel) {
-                    dynamicDataViewPanels.delete(viewId);
+                listViewGenerations.delete(panel.webview);
+                if (dynamicDataViewPanels.get(viewId) !== panel) {
+                    return;
                 }
+                dynamicDataViewPanels.delete(viewId);
                 void sessionRequest({
                     method: 'dataview_dispose',
                     params: { view_id: viewId },
@@ -1123,7 +1135,7 @@ export async function showDataView(source: string, type: string, title: string,
             });
         }
         panel.webview.html = getListHtml(
-            panel.webview, title, navigation, source === 'vector'
+            panel.webview, title, navigation
         );
     } else {
         await commands.executeCommand('vscode.open', Uri.file(file), {
@@ -1830,9 +1842,10 @@ export async function getTableHtml(webview: Webview, file: string | undefined, t
 export function getListHtml(
     webview: Webview,
     title: string,
-    navigation?: ListViewNavigation,
-    vector = false
+    navigation?: ListViewNavigation
 ): string {
+    const generation = ++dynamicDataViewReloadRevision;
+    listViewGenerations.set(webview, generation);
     const icon = new UriIcon('open-preview-codicon');
     const darkIcon = webview.asWebviewUri(icon.dark).toString();
     const lightIcon = webview.asWebviewUri(icon.light).toString();
@@ -1968,18 +1981,18 @@ export function getListHtml(
     }
     
 
-
+
     

         
-        
+        
     

     
     

     
     
 
 
diff --git a/src/test/suite/listViewer.test.ts b/src/test/suite/listViewer.test.ts
index 5bf6d47e8..06d9ef815 100644
--- a/src/test/suite/listViewer.test.ts
+++ b/src/test/suite/listViewer.test.ts
@@ -35,19 +35,27 @@ interface Request {
 
 function createViewer(initial: ListViewNavigation = {
     title: 'x', path: [], breadcrumbs: [{ label: 'x', path: [] }],
-}, vector = false) {
+}) {
     const root = new Element('div');
     const back = new Element('button');
     const breadcrumbs = new Element('nav');
     const status = new Element('div');
+    const bodyClasses = new Set();
     const elements: Record = { list: root, back, breadcrumbs, 'navigation-status': status };
     const messages: Request[] = [];
     let receive: (event: unknown) => void = () => undefined;
-    vm.runInNewContext(getListViewerScript(7, initial, vector), {
+    vm.runInNewContext(getListViewerScript(7, initial), {
         acquireVsCodeApi: () => ({ postMessage: (message: Request) => {
             messages.push(JSON.parse(JSON.stringify(message)) as Request);
         } }),
         document: {
+            body: { classList: { toggle: (name: string, enabled: boolean) => {
+                if (enabled) {
+                    bodyClasses.add(name);
+                } else {
+                    bodyClasses.delete(name);
+                }
+            } } },
             createElement: (tag: string) => new Element(tag),
             getElementById: (id: string) => elements[id] ?? new Element('template'),
         },
@@ -56,7 +64,10 @@ function createViewer(initial: ListViewNavigation = {
     const reply = (request: Request, result: Record) => receive({
         data: { ...request, children: [], next_start: null, ...result },
     });
-    return { get root() { return root.children[0]; }, viewport: root, back, breadcrumbs, status, messages, reply };
+    return {
+        get root() { return root.children[0]; },
+        viewport: root, back, breadcrumbs, status, messages, reply, bodyClasses,
+    };
 }
 
 suite('List viewer', () => {
@@ -143,9 +154,11 @@ suite('List viewer', () => {
         reply(messages[0], { children: [{ label: '$ a', str: 'List of 1', index: 1, viewable: true, has_children: true }] });
         const entry = root.children[0].children[0];
         assert.strictEqual(entry.tag, 'details');
+        assert.strictEqual(entry.children[1].childElementCount, 0);
         assert.strictEqual(messages.length, 1);
         entry.open = true;
         entry.fire('toggle');
+        assert.strictEqual(entry.children[1].childElementCount, 3);
         assert.deepStrictEqual(messages[1].path, [1]);
         reply(messages[1], { children: [{ label: '$ b', str: 'List of 1', index: 2, viewable: true, has_children: true }] });
         entry.open = false;
@@ -198,7 +211,9 @@ suite('List viewer', () => {
     });
 
     test('renders vector values as simple indexed rows', () => {
-        const viewer = createViewer(undefined, true);
+        const viewer = createViewer({
+            title: 'x', path: [], breadcrumbs: [{ label: 'x', path: [] }], vector: true,
+        });
         viewer.reply(viewer.messages[0], {
             children: [{
                 label: '[1]', str: '12.4', index: 1,
@@ -212,6 +227,53 @@ suite('List viewer', () => {
         assert.ok(!row.children.some(child => child.tag === 'button'));
     });
 
+    test('vectors share list navigation, Back and cached pages, including late page responses', () => {
+        const rootNavigation = { title: 'x', path: [], breadcrumbs: [{ label: 'x', path: [] }] };
+        const vectorNavigation = {
+            title: 'x$v', path: [1], vector: true,
+            breadcrumbs: [{ label: 'x', path: [] }, { label: 'v', path: [1] }],
+        };
+        const viewer = createViewer(rootNavigation);
+        const { messages, reply, back, bodyClasses } = viewer;
+        reply(messages[0], { children: [{ label: '$ v', index: 1, viewable: true }] });
+        const original = viewer.root;
+        viewer.viewport.scrollTop = 120;
+        const button = original.children[0].children[0].children[0].children.at(-1);
+        assert.ok(button);
+        const click = { preventDefault: () => undefined, stopPropagation: () => undefined };
+        button.fire('click', click);
+        reply(messages[1], { message: 'listview/navigation', navigation: vectorNavigation });
+        const vectorPage = viewer.root;
+        assert.deepStrictEqual(messages[2].path, [1]);
+        assert.ok(bodyClasses.has('vector'));
+        assert.strictEqual(back.disabled, false);
+
+        back.fire('click');
+        reply(messages[3], { message: 'listview/navigation', navigation: rootNavigation });
+        assert.strictEqual(viewer.root, original);
+        assert.strictEqual(viewer.viewport.scrollTop, 120);
+        assert.ok(!bodyClasses.has('vector'));
+        reply(messages[2], {
+            children: [{ label: '[1]', str: '42', index: 1, viewable: false, has_children: false }],
+        });
+
+        button.fire('click', click);
+        reply(messages[4], { message: 'listview/navigation', navigation: vectorNavigation });
+        assert.strictEqual(viewer.root, vectorPage);
+        assert.strictEqual(messages.length, 5);
+        const row = vectorPage.children[0].children[0].children[0];
+        assert.deepStrictEqual(row.children.map(child => child.className), ['label', 'str']);
+        assert.ok(bodyClasses.has('vector'));
+        viewer.breadcrumbs.children[0].fire('click');
+        reply(messages[5], { message: 'listview/navigation', navigation: rootNavigation });
+        assert.strictEqual(viewer.root, original);
+        assert.ok(!bodyClasses.has('vector'));
+        back.fire('click');
+        reply(messages[6], { message: 'listview/navigation', navigation: vectorNavigation });
+        assert.strictEqual(viewer.root, vectorPage);
+        assert.ok(bodyClasses.has('vector'));
+    });
+
     test('ignores old viewer responses and hides open buttons for unavailable items', () => {
         const { root, messages, reply } = createViewer();
         reply(messages[0], { generation: 6, children: [{ label: 'stale' }] });
diff --git a/src/test/suite/listViewerPanels.test.ts b/src/test/suite/listViewerPanels.test.ts
index 418f009c6..9bec1de2a 100644
--- a/src/test/suite/listViewerPanels.test.ts
+++ b/src/test/suite/listViewerPanels.test.ts
@@ -62,13 +62,55 @@ suite('List viewer panels', () => {
         assert.strictEqual(panels[0].title, 'x$a$b');
         await session.showDataView('list', 'json', 'y', '', 'Two', 'test-list-y');
         assert.strictEqual(create.callCount, 3);
-        await session.showDataView('vector', 'json', 'x$id', '', 'Two', 'test-vector-x');
-        assert.strictEqual(create.callCount, 4);
+        await session.showDataView('list', 'json', 'x$id', '', 'Two', 'test-list-x', {
+            title: 'x$id', path: [1], vector: true,
+            breadcrumbs: [{ label: 'x', path: [] }, { label: 'id', path: [1] }],
+        });
+        assert.strictEqual(create.callCount, 3);
+        assert.strictEqual(panels[0].title, 'x$id');
+        await session.showDataView('list', 'json', 'x', '', 'Two', 'test-list-x');
+        assert.strictEqual(create.callCount, 3);
+        assert.strictEqual(panels[0].title, 'x');
         const first = panels.shift();
         assert.ok(first);
         first.dispose();
         await session.showDataView('list', 'json', 'x', '', 'Two', 'test-list-x');
-        assert.strictEqual(create.callCount, 5);
+        assert.strictEqual(create.callCount, 4);
+    });
+
+    test('ignores requests and replies from a previous list page after panel reuse', async () => {
+        let receive: (message: unknown) => Promise = () => Promise.resolve();
+        const postMessage = sandbox.stub().resolves(true);
+        const disposed = new vscode.EventEmitter();
+        const panel = {
+            title: '', viewColumn: vscode.ViewColumn.Two, reveal: sandbox.stub(),
+            webview: {
+                html: '', asWebviewUri: (uri: vscode.Uri) => uri, postMessage,
+                onDidReceiveMessage: (listener: typeof receive) => { receive = listener; },
+            },
+            onDidDispose: disposed.event,
+            dispose: () => { disposed.fire(); disposed.dispose(); },
+        } as unknown as vscode.WebviewPanel;
+        panels.push(panel);
+        sandbox.stub(vscode.window, 'createWebviewPanel').returns(panel);
+        const generation = () => Number(/const generation = (\d+)/.exec(panel.webview.html)?.[1]);
+        await session.showDataView('list', 'json', 'x', '', 'Two', 'test-list-generation');
+
+        for (const message of ['listview/navigate', 'listview/page']) {
+            const request = { message, generation: generation(), requestId: 1, path: [], start: 1 };
+            // sessionRequest settles asynchronously even without an attached R session.
+            const pending = receive(request);
+            await session.showDataView('list', 'json', 'x$updated', '', 'Two', 'test-list-generation');
+            await pending;
+            sinon.assert.notCalled(postMessage);
+            await receive(request);
+            sinon.assert.notCalled(postMessage);
+            assert.strictEqual(panel.title, 'x$updated');
+        }
+        await receive({ message: 'listview/page', generation: generation(), requestId: 2, path: [], start: 1 });
+        sinon.assert.calledOnce(postMessage);
+        const response = postMessage.firstCall.args[0] as { generation: number };
+        assert.strictEqual(response.generation, generation());
     });
 
     test('supported workspace children retain open actions alongside expansion', () => {

From 6d0ab112ce1b1134180f0452ac5f14c6d71a59cd Mon Sep 17 00:00:00 2001
From: "4111978+Fred-Wu@users.noreply.github.com"
 <4111978+Fred-Wu@users.noreply.github.com>
Date: Sun, 4 Oct 2026 12:35:04 +1100
Subject: [PATCH 12/30] Implement session-aware data/list viewers

---
 src/interactive/backend.ts                |   4 +-
 src/interactive/manager.ts                |   2 +-
 src/session.ts                            |  80 ++++----
 src/test/suite/dataViewerSessions.test.ts | 224 ++++++++++++++++++++++
 4 files changed, 268 insertions(+), 42 deletions(-)
 create mode 100644 src/test/suite/dataViewerSessions.test.ts

diff --git a/src/interactive/backend.ts b/src/interactive/backend.ts
index b4460e964..a4fd57403 100644
--- a/src/interactive/backend.ts
+++ b/src/interactive/backend.ts
@@ -9,7 +9,7 @@ export interface RuntimeMetadata {
     rPath?: string;
     libraryPaths?: string[];
 }
-export type InspectionMethod = 'workspace' | 'workspace_children' | 'hover' | 'completion' |
+export type InspectionMethod = 'workspace' | 'workspace_children' | 'workspace_view' | 'listview_navigate' | 'listview_view' | 'hover' | 'completion' |
     'dataview_init' | 'dataview_page' | 'dataview_dispose';
 export interface InspectionRequest { method: InspectionMethod; params: Record; timeout?: number }
 export interface InputReply { value: string }
@@ -56,7 +56,7 @@ export interface SessionBackend {
 export type BackendFactory = (settings: AgentSettings) => SessionBackend;
 
 export function inspectionMethod(value: unknown): InspectionMethod {
-    if (!['workspace', 'workspace_children', 'hover', 'completion', 'dataview_init', 'dataview_page', 'dataview_dispose'].includes(String(value))) {
+    if (!['workspace', 'workspace_children', 'workspace_view', 'listview_navigate', 'listview_view', 'hover', 'completion', 'dataview_init', 'dataview_page', 'dataview_dispose'].includes(String(value))) {
         throw new Error('Unsupported inspection method');
     }
     return value as InspectionMethod;
diff --git a/src/interactive/manager.ts b/src/interactive/manager.ts
index 199beddca..57c0c4098 100644
--- a/src/interactive/manager.ts
+++ b/src/interactive/manager.ts
@@ -1184,7 +1184,7 @@ export class InteractiveManager implements vscode.Disposable, vscode.TreeDataPro
             switch (message.action) {
                 case 'table':
                     if (data.kind !== 'table') { return; }
-                    await session.showDataView('table', 'json', `${view.client.manifest.label}: ${data.fullViewId ? 'full table' : 'table'}`, '', 'Beside', String(data.fullViewId ?? data.viewId), undefined, view.target); break;
+                    await session.showDataView('table', 'json', `${view.client.manifest.label}: ${data.fullViewId ? 'full table' : 'table'}`, '', 'Beside', String(data.fullViewId ?? data.viewId), undefined, view.target?.sessionId ?? null); break;
                 case 'page': {
                     if (data.kind !== 'table') { return; }
                     result = await queryTablePage(data, message, request => view.client.request('inspect', request)); break;
diff --git a/src/session.ts b/src/session.ts
index 58072c8b8..69dd3d5fc 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -234,8 +234,24 @@ function escapeHtml(text: string): string {
     return text.replace(/[&<>"']/g, c => map[c]);
 }
 
-function attachDynamicDataViewBridge(panel: vscode.WebviewPanel, viewId: string, baseTitle: string, owner: Session | undefined): void {
-    const panelKey = `${owner?.sessionId ?? ''}:${viewId}`;
+function registerDataViewPanel(panel: vscode.WebviewPanel, key: string, viewId: string, sessionId: string | null): void {
+    dynamicDataViewPanels.set(key, panel);
+    panel.onDidDispose(() => {
+        listViewGenerations.delete(panel.webview);
+        if (dynamicDataViewPanels.get(key) !== panel) {
+            return;
+        }
+        dynamicDataViewPanels.delete(key);
+        // Interactive transcripts retain this handle after the expanded viewer closes.
+        if (sessions.get(sessionId ?? '')?.requester) { return; }
+        void sessionRequest({
+            method: 'dataview_dispose',
+            params: { view_id: viewId },
+        }, sessionId);
+    });
+}
+
+function attachDynamicDataViewBridge(panel: vscode.WebviewPanel, viewId: string, sessionId: string | null): void {
     const postResponse = (requestId: number, ok: boolean, result?: unknown, error?: string) => {
         void panel.webview.postMessage({
             message: 'dataview/response',
@@ -257,7 +273,7 @@ function attachDynamicDataViewBridge(panel: vscode.WebviewPanel, viewId: string,
                 const result = await sessionRequest({
                     method: 'dataview_init',
                     params: { view_id: viewId },
-                }, owner) as DataViewInitResult | undefined;
+                }, sessionId) as DataViewInitResult | undefined;
                 if (!result || !Array.isArray(result.columns) || typeof result.totalRows !== 'number') {
                     throw new Error('Invalid dataview_init response');
                 }
@@ -275,7 +291,7 @@ function attachDynamicDataViewBridge(panel: vscode.WebviewPanel, viewId: string,
                         sortModel: Array.isArray(msg.sortModel) ? msg.sortModel : [],
                         filterModel: msg.filterModel ?? {},
                     },
-                }, owner) as DataViewPageResult | undefined;
+                }, sessionId) as DataViewPageResult | undefined;
                 if (!result || !Array.isArray(result.rows) ||
                     typeof result.totalRows !== 'number' ||
                     typeof result.totalUnfiltered !== 'number') {
@@ -290,19 +306,6 @@ function attachDynamicDataViewBridge(panel: vscode.WebviewPanel, viewId: string,
             postResponse(msg.requestId, false, undefined, e instanceof Error ? e.message : String(e));
         }
     });
-
-    panel.onDidDispose(() => {
-        if (dynamicDataViewPanels.get(panelKey) !== panel) {
-            return;
-        }
-        dynamicDataViewPanels.delete(panelKey);
-        // Interactive transcripts retain this handle after the expanded viewer closes.
-        if (owner?.requester) { return; }
-        void sessionRequest({
-            method: 'dataview_dispose',
-            params: { view_id: viewId },
-        }, owner);
-    });
 }
 
 export function deploySessionWatcher(extensionPath: string): void {
@@ -1012,13 +1015,18 @@ export function openExternalBrowser(): void {
     }
 }
 
-export async function showDataView(source: string, type: string, title: string, file: string, viewer: string, viewId?: string, navigation?: ListViewNavigation, owner = activeSession): Promise {
+export async function showDataView(
+    source: string, type: string, title: string, file: string, viewer: string,
+    viewId?: string, navigation?: ListViewNavigation,
+    sessionId: string | null = activeSession?.sessionId ?? null,
+): Promise {
     resDir ??= path.join(extensionContext.extensionPath, 'dist', 'resources');
     console.info(`[showDataView] source: ${source}, type: ${type}, title: ${title}, file: ${file}, viewer: ${viewer}, viewId: ${String(viewId ?? '')}`);
+    const panelKey = JSON.stringify([sessionId, viewId]);
 
     if (source === 'table') {
         if (viewId) {
-            const existing = dynamicDataViewPanels.get(`${owner?.sessionId ?? ''}:${viewId}`);
+            const existing = dynamicDataViewPanels.get(panelKey);
             if (existing) {
                 existing.title = title;
                 existing.reveal(existing.viewColumn, true);
@@ -1041,14 +1049,14 @@ export async function showDataView(source: string, type: string, title: string,
             });
         panel.iconPath = new UriIcon('open-preview');
         if (viewId) {
-            dynamicDataViewPanels.set(`${owner?.sessionId ?? ''}:${viewId}`, panel);
-            attachDynamicDataViewBridge(panel, viewId, title, owner);
+            registerDataViewPanel(panel, panelKey, viewId, sessionId);
+            attachDynamicDataViewBridge(panel, viewId, sessionId);
         }
         const content = await getTableHtml(panel.webview, file || undefined, title);
         panel.webview.html = content;
     } else if (source === 'list') {
         if (viewId) {
-            const existing = dynamicDataViewPanels.get(viewId);
+            const existing = dynamicDataViewPanels.get(panelKey);
             if (existing) {
                 existing.title = title;
                 existing.reveal(existing.viewColumn, true);
@@ -1072,7 +1080,7 @@ export async function showDataView(source: string, type: string, title: string,
             });
         panel.iconPath = new UriIcon('preview');
         if (viewId) {
-            dynamicDataViewPanels.set(viewId, panel);
+            registerDataViewPanel(panel, panelKey, viewId, sessionId);
             panel.webview.onDidReceiveMessage(async (message: {
                 message?: string; index?: number; start?: number; requestId?: number;
                 path?: number[]; generation?: number;
@@ -1088,7 +1096,7 @@ export async function showDataView(source: string, type: string, title: string,
                     const result = await sessionRequest({
                         method: message.message === 'listview/navigate' ? 'listview_navigate' : 'listview_view',
                         params: { view_id: viewId, index: message.index, path: message.path },
-                    }) as ListViewNavigation | boolean | undefined;
+                    }, sessionId) as ListViewNavigation | boolean | undefined;
                     if (message.generation !== listViewGenerations.get(panel.webview)) {
                         return;
                     }
@@ -1109,7 +1117,7 @@ export async function showDataView(source: string, type: string, title: string,
                     const page = await sessionRequest({
                         method: 'workspace_children',
                         params: { view_id: viewId, start: message.start, path: message.path },
-                    }) as { children?: unknown; next_start?: number | null } | undefined;
+                    }, sessionId) as { children?: unknown; next_start?: number | null } | undefined;
                     if (message.generation !== listViewGenerations.get(panel.webview)) {
                         return;
                     }
@@ -1122,17 +1130,6 @@ export async function showDataView(source: string, type: string, title: string,
                     });
                 }
             });
-            panel.onDidDispose(() => {
-                listViewGenerations.delete(panel.webview);
-                if (dynamicDataViewPanels.get(viewId) !== panel) {
-                    return;
-                }
-                dynamicDataViewPanels.delete(viewId);
-                void sessionRequest({
-                    method: 'dataview_dispose',
-                    params: { view_id: viewId },
-                });
-            });
         }
         panel.webview.html = getListHtml(
             panel.webview, title, navigation
@@ -2240,6 +2237,7 @@ async function handleNotification(message: Record, socket: IpcS
                         viewer,
                         params.view_id ? String(params.view_id) : undefined,
                         params.navigation as ListViewNavigation | undefined,
+                        socket._sessionId ?? null,
                     );
                 }
             }
@@ -2383,10 +2381,14 @@ export async function cleanupSession(sessionId: string, closingSocket?: IpcSocke
     }
 }
 
-export async function sessionRequest(data: Record, target = activeSession): Promise {
+export async function sessionRequest(
+    data: Record, target: Session | string | null | undefined = activeSession,
+): Promise {
     try {
-        if (target?.requester) { return await target.requester(data); }
-        const socket = target?.socket ?? pipeClient;
+        const owner = typeof target === 'string' ? sessions.get(target) : target;
+        if (owner?.requester) { return await owner.requester(data); }
+        // An explicitly bound viewer must never fall back to the active session.
+        const socket = owner?.socket ?? (target === undefined ? pipeClient : undefined);
         if (!socket || socket.destroyed) {
             throw new Error('IPC socket is not connected');
         }
diff --git a/src/test/suite/dataViewerSessions.test.ts b/src/test/suite/dataViewerSessions.test.ts
new file mode 100644
index 000000000..3d7b576bb
--- /dev/null
+++ b/src/test/suite/dataViewerSessions.test.ts
@@ -0,0 +1,224 @@
+import * as assert from 'assert';
+import * as net from 'net';
+import * as path from 'path';
+import * as sinon from 'sinon';
+import * as vscode from 'vscode';
+import * as extension from '../../extension';
+import * as session from '../../session';
+import * as util from '../../util';
+import { mockExtensionContext } from '../common/mockvscode';
+
+interface Request {
+    id: number;
+    method: string;
+    params?: { view_id?: string };
+}
+
+interface Client {
+    id: string;
+    socket: net.Socket;
+    requests: Request[];
+}
+
+interface Panel {
+    panel: vscode.WebviewPanel;
+    receive: (message: unknown) => Promise;
+    replies: Array<{ ok?: boolean; error?: string }>;
+}
+
+async function waitFor(condition: () => boolean): Promise {
+    const deadline = Date.now() + 5000;
+    while (!condition()) {
+        if (Date.now() > deadline) {
+            throw new Error('Timed out waiting for viewer IPC');
+        }
+        await new Promise(resolve => setTimeout(resolve, 10));
+    }
+}
+
+suite('Viewer session ownership', () => {
+    let sandbox: sinon.SinonSandbox;
+    const clients: Client[] = [];
+    const panels: Panel[] = [];
+
+    setup(() => {
+        sandbox = sinon.createSandbox();
+        const root = path.join(__dirname, '..', '..', '..');
+        mockExtensionContext(root, sandbox);
+        sandbox.stub(extension, 'enableSessionWatcher').value(true);
+        sandbox.stub(util, 'config').returns({
+            get: (_key: string, defaultValue: unknown) => defaultValue,
+        } as vscode.WorkspaceConfiguration);
+        session.deploySessionWatcher(root);
+        sandbox.stub(vscode.window, 'createWebviewPanel').callsFake((_type, title) => {
+            const disposed = new vscode.EventEmitter();
+            let closed = false;
+            const item: Panel = {
+                panel: undefined as unknown as vscode.WebviewPanel,
+                receive: () => Promise.resolve(), replies: [],
+            };
+            item.panel = {
+                title, viewColumn: vscode.ViewColumn.Two, reveal: sandbox.stub(),
+                webview: {
+                    html: '', asWebviewUri: (uri: vscode.Uri) => uri,
+                    onDidReceiveMessage: (listener: Panel['receive']) => { item.receive = listener; },
+                    postMessage: (reply: Panel['replies'][number]) => {
+                        item.replies.push(reply);
+                        return Promise.resolve(true);
+                    },
+                },
+                onDidDispose: disposed.event,
+                dispose: () => {
+                    if (!closed) {
+                        closed = true;
+                        disposed.fire();
+                        disposed.dispose();
+                    }
+                },
+            } as unknown as vscode.WebviewPanel;
+            panels.push(item);
+            return item.panel;
+        });
+    });
+
+    teardown(async () => {
+        panels.splice(0).forEach(item => { item.panel.dispose(); });
+        for (const client of clients.splice(0)) {
+            await session.cleanupSession(client.id);
+            client.socket.destroy();
+        }
+        await session.shutdownSessionWatcher();
+        sandbox.restore();
+    });
+
+    function notify(client: Client, method: string, params: Record): void {
+        client.socket.write(JSON.stringify({ jsonrpc: '2.0', method, params }) + '\n');
+    }
+
+    async function attach(id: string): Promise {
+        const previousSocket = session.activeSession?.socket;
+        const socket = net.createConnection(await session.getGlobalPipePath());
+        const client = { id, socket, requests: [] as Request[] };
+        clients.push(client);
+        let buffer = '';
+        socket.on('data', (data: Buffer) => {
+            buffer += data.toString();
+            let newline: number;
+            while ((newline = buffer.indexOf('\n')) >= 0) {
+                const request = JSON.parse(buffer.slice(0, newline)) as Request;
+                buffer = buffer.slice(newline + 1);
+                client.requests.push(request);
+                let result: unknown = true;
+                switch (request.method) {
+                    case 'workspace': result = { globalenv: {}, search: [], loaded_namespaces: [] }; break;
+                    case 'dataview_init': result = { columns: [], totalRows: 1 }; break;
+                    case 'dataview_page': result = { rows: [{ owner: id }], totalRows: 1, totalUnfiltered: 1 }; break;
+                    case 'workspace_children': result = { children: [], next_start: null }; break;
+                    case 'listview_navigate':
+                    case 'listview_view':
+                        result = { title: 'x$child', path: [1], breadcrumbs: [{ label: 'x', path: [] }] };
+                        break;
+                }
+                socket.write(JSON.stringify({ jsonrpc: '2.0', id: request.id, result }) + '\n');
+            }
+        });
+        await new Promise((resolve, reject) => {
+            socket.once('connect', resolve);
+            socket.once('error', reject);
+        });
+        notify(client, 'attach', {
+            protocol_version: 1, session_id: id, host: 'viewer-test-host', pid: id,
+            version: '4.6.0', tempdir: '/tmp', wd: '/tmp',
+        });
+        await waitFor(() => session.activeSession?.sessionId === id &&
+            session.activeSession.socket !== previousSocket);
+        // A round trip ensures the new connection has completed its handshake.
+        await session.sessionRequest({ method: 'workspace' }, id);
+        return client;
+    }
+
+    async function open(client: Client, source: 'list' | 'table', existing?: Panel): Promise {
+        const count = panels.length;
+        const html = existing?.panel.webview.html;
+        notify(client, 'dataview', {
+            source, type: 'json', title: 'x', view_id: `same-${source}-id`,
+            navigation: { title: 'x', path: [], breadcrumbs: [{ label: 'x', path: [] }] },
+        });
+        await waitFor(() => existing ? existing.panel.webview.html !== html : panels.length > count);
+        if (existing) {
+            assert.strictEqual(panels.length, count);
+        }
+        return existing ?? panels[count];
+    }
+
+    async function send(panel: Panel, message: Record): Promise {
+        const generation = Number(/const generation = (\d+)/.exec(panel.panel.webview.html)?.[1]);
+        await panel.receive({ generation, requestId: 1, path: [], start: 1, ...message });
+    }
+
+    const viewerRequests = (client: Client) => client.requests.filter(request => request.method !== 'workspace');
+
+    test('identical viewer ids stay separate and background views keep their originating session', async () => {
+        const a = await attach('viewer-session-a');
+        const b = await attach('viewer-session-b');
+        const aList = await open(a, 'list');
+        const aTable = await open(a, 'table');
+        const bList = await open(b, 'list');
+        const bTable = await open(b, 'table');
+        assert.strictEqual(panels.length, 4);
+        await open(a, 'list', aList);
+        await open(a, 'table', aTable);
+        assert.strictEqual(session.activeSession?.sessionId, b.id);
+
+        const exercise = async (list: Panel, table: Panel) => {
+            await send(table, { message: 'dataview/request', action: 'init' });
+            await send(table, { message: 'dataview/request', action: 'page', startRow: 0, endRow: 1 });
+            await send(list, { message: 'listview/page' });
+            await send(list, { message: 'listview/navigate' });
+            await send(list, { message: 'listview/view', index: 1 });
+        };
+        const expected = ['dataview_init', 'dataview_page', 'workspace_children', 'listview_navigate', 'listview_view'];
+        await exercise(aList, aTable);
+        assert.deepStrictEqual(viewerRequests(a).map(request => request.method), expected);
+        assert.deepStrictEqual(viewerRequests(b), []);
+        assert.strictEqual(await session.activateSessionById(a.id), true);
+        await exercise(bList, bTable);
+        assert.deepStrictEqual(viewerRequests(b).map(request => request.method), expected);
+
+        bList.panel.dispose();
+        bTable.panel.dispose();
+        await waitFor(() => viewerRequests(b).length === 7);
+        assert.deepStrictEqual(viewerRequests(b).slice(-2).map(request => request.params?.view_id),
+            ['same-list-id', 'same-table-id']);
+        assert.strictEqual(viewerRequests(a).length, 5);
+        await open(a, 'list', aList);
+        await open(a, 'table', aTable);
+    });
+
+    test('viewers follow the same session on reconnect and never fall back after disconnect', async () => {
+        const a = await attach('viewer-reconnect-a');
+        const list = await open(a, 'list');
+        const table = await open(a, 'table');
+        const b = await attach('viewer-reconnect-b');
+        const replacement = await attach(a.id);
+        assert.strictEqual(await session.activateSessionById(b.id), true);
+        await open(replacement, 'list', list);
+        await open(replacement, 'table', table);
+        await send(list, { message: 'listview/page' });
+        await send(table, { message: 'dataview/request', action: 'init' });
+        assert.deepStrictEqual(viewerRequests(replacement).map(request => request.method),
+            ['workspace_children', 'dataview_init']);
+        assert.deepStrictEqual(viewerRequests(a), []);
+        assert.deepStrictEqual(viewerRequests(b), []);
+
+        await session.cleanupSession(a.id);
+        await send(list, { message: 'listview/page' });
+        await send(table, { message: 'dataview/request', action: 'page' });
+        assert.ok(list.replies.at(-1)?.error);
+        assert.strictEqual(table.replies.at(-1)?.ok, false);
+        list.panel.dispose();
+        table.panel.dispose();
+        assert.deepStrictEqual(viewerRequests(b), []);
+        assert.strictEqual(session.activeSession?.sessionId, b.id);
+    });
+});

From 2bfdc43f133e6b4679473ef844cc20c597b7a0a6 Mon Sep 17 00:00:00 2001
From: "4111978+Fred-Wu@users.noreply.github.com"
 <4111978+Fred-Wu@users.noreply.github.com>
Date: Sun, 4 Oct 2026 12:50:39 +1100
Subject: [PATCH 13/30] Fixed viewer not reopening after cleanup

---
 src/session.ts                          | 22 +++++++-----
 src/test/suite/listViewerPanels.test.ts | 47 +++++++++++++++++++++++++
 2 files changed, 60 insertions(+), 9 deletions(-)

diff --git a/src/session.ts b/src/session.ts
index 69dd3d5fc..821bbf4a2 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -235,9 +235,11 @@ function escapeHtml(text: string): string {
 }
 
 function registerDataViewPanel(panel: vscode.WebviewPanel, key: string, viewId: string, sessionId: string | null): void {
+    // The panel's webview getter throws once onDidDispose fires.
+    const webview = panel.webview;
     dynamicDataViewPanels.set(key, panel);
     panel.onDidDispose(() => {
-        listViewGenerations.delete(panel.webview);
+        listViewGenerations.delete(webview);
         if (dynamicDataViewPanels.get(key) !== panel) {
             return;
         }
@@ -252,8 +254,9 @@ function registerDataViewPanel(panel: vscode.WebviewPanel, key: string, viewId:
 }
 
 function attachDynamicDataViewBridge(panel: vscode.WebviewPanel, viewId: string, sessionId: string | null): void {
+    const webview = panel.webview;
     const postResponse = (requestId: number, ok: boolean, result?: unknown, error?: string) => {
-        void panel.webview.postMessage({
+        void webview.postMessage({
             message: 'dataview/response',
             requestId,
             ok,
@@ -262,7 +265,7 @@ function attachDynamicDataViewBridge(panel: vscode.WebviewPanel, viewId: string,
         });
     };
 
-    panel.webview.onDidReceiveMessage(async (raw: unknown) => {
+    webview.onDidReceiveMessage(async (raw: unknown) => {
         const msg = raw as Partial;
         if (msg.message !== 'dataview/request' || typeof msg.requestId !== 'number') {
             return;
@@ -1081,11 +1084,12 @@ export async function showDataView(
         panel.iconPath = new UriIcon('preview');
         if (viewId) {
             registerDataViewPanel(panel, panelKey, viewId, sessionId);
-            panel.webview.onDidReceiveMessage(async (message: {
+            const webview = panel.webview;
+            webview.onDidReceiveMessage(async (message: {
                 message?: string; index?: number; start?: number; requestId?: number;
                 path?: number[]; generation?: number;
             }) => {
-                if (message.generation !== listViewGenerations.get(panel.webview)) {
+                if (message.generation !== listViewGenerations.get(webview)) {
                     return;
                 }
                 if (!Array.isArray(message.path) || !message.path.every(index => Number.isSafeInteger(index) && index > 0)) {
@@ -1097,7 +1101,7 @@ export async function showDataView(
                         method: message.message === 'listview/navigate' ? 'listview_navigate' : 'listview_view',
                         params: { view_id: viewId, index: message.index, path: message.path },
                     }, sessionId) as ListViewNavigation | boolean | undefined;
-                    if (message.generation !== listViewGenerations.get(panel.webview)) {
+                    if (message.generation !== listViewGenerations.get(webview)) {
                         return;
                     }
                     const navigation = result && typeof result === 'object' && Array.isArray(result.breadcrumbs)
@@ -1105,7 +1109,7 @@ export async function showDataView(
                     if (navigation) {
                         panel.title = navigation.title;
                     }
-                    void panel.webview.postMessage({
+                    void webview.postMessage({
                         message: 'listview/navigation',
                         generation: message.generation,
                         requestId: message.requestId,
@@ -1118,10 +1122,10 @@ export async function showDataView(
                         method: 'workspace_children',
                         params: { view_id: viewId, start: message.start, path: message.path },
                     }, sessionId) as { children?: unknown; next_start?: number | null } | undefined;
-                    if (message.generation !== listViewGenerations.get(panel.webview)) {
+                    if (message.generation !== listViewGenerations.get(webview)) {
                         return;
                     }
-                    void panel.webview.postMessage({
+                    void webview.postMessage({
                         message: 'listview/page',
                         generation: message.generation,
                         requestId: message.requestId,
diff --git a/src/test/suite/listViewerPanels.test.ts b/src/test/suite/listViewerPanels.test.ts
index 9bec1de2a..ad757b28d 100644
--- a/src/test/suite/listViewerPanels.test.ts
+++ b/src/test/suite/listViewerPanels.test.ts
@@ -22,6 +22,53 @@ suite('List viewer panels', () => {
         sandbox.restore();
     });
 
+    for (const source of ['list', 'table']) {
+        test(`reopens a disposed ${source} viewer using real VS Code panels`, async () => {
+            const create = sandbox.spy(vscode.window, 'createWebviewPanel');
+            const viewId = `test-real-${source}`;
+            const open = async () => {
+                try {
+                    await session.showDataView(source, 'json', 'x', '', 'Two', viewId);
+                } finally {
+                    for (const panel of create.returnValues) {
+                        if (!panels.includes(panel)) {
+                            panels.push(panel);
+                        }
+                    }
+                }
+            };
+
+            await open();
+            await open();
+            sinon.assert.calledOnce(create);
+            create.firstCall.returnValue.dispose();
+            await open();
+            sinon.assert.calledTwice(create);
+            assert.notStrictEqual(create.firstCall.returnValue, create.secondCall.returnValue);
+            create.secondCall.returnValue.dispose();
+            await open();
+            sinon.assert.calledThrice(create);
+        });
+
+        test(`handles pending ${source} requests when a real VS Code panel closes`, async () => {
+            const panel = vscode.window.createWebviewPanel('dataview', 'x', vscode.ViewColumn.Two, {});
+            panels.push(panel);
+            const receive = sandbox.spy(panel.webview, 'onDidReceiveMessage');
+            sandbox.stub(vscode.window, 'createWebviewPanel').returns(panel);
+            await session.showDataView(source, 'json', 'x', '', 'Two', `test-pending-${source}`);
+            const generation = Number(/const generation = (\d+)/.exec(panel.webview.html)?.[1]);
+            const listener = receive.firstCall.args[0] as (message: unknown) => Promise;
+            // With no R session, requests settle asynchronously with an unavailable response.
+            const pending = source === 'table'
+                ? [listener({ message: 'dataview/request', action: 'page', requestId: 1 })]
+                : ['listview/page', 'listview/navigate'].map(message => listener({
+                    message, generation, requestId: 1, path: [], start: 1,
+                }));
+            panel.dispose();
+            await Promise.all(pending);
+        });
+    }
+
     test('reuses separate list and table panels, updates titles, and reopens closed viewers', async () => {
         const reveals: sinon.SinonStub[] = [];
         const create = sandbox.stub(vscode.window, 'createWebviewPanel').callsFake((_type, title) => {

From 65d61d1ec83daac929d3849850adcb48f405683f Mon Sep 17 00:00:00 2001
From: "4111978+Fred-Wu@users.noreply.github.com"
 <4111978+Fred-Wu@users.noreply.github.com>
Date: Sun, 4 Oct 2026 13:01:26 +1100
Subject: [PATCH 14/30] fix(viewer): avoid evaluating active root bindings
 twice

---
 sess/R/handlers.R                  | 10 ++++++++--
 sess/inst/tinytest/test-listview.R | 29 +++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/sess/R/handlers.R b/sess/R/handlers.R
index e506d788b..e303ab327 100644
--- a/sess/R/handlers.R
+++ b/sess/R/handlers.R
@@ -201,9 +201,15 @@ listview_expression_context <- function(expression, envir, owner) {
       selectors <- c(list(list(kind = "index", value = value)), selectors)
       expression <- expression[[2L]]
     }
-    if (!is.symbol(expression)) return(NULL)
+    if (!length(selectors) || !is.symbol(expression)) return(NULL)
     name <- as.character(expression)
-    root <- listview_state(get(name, envir = envir, inherits = TRUE), name, owner)
+    while (!identical(envir, emptyenv()) && !exists(name, envir = envir, inherits = FALSE)) {
+      envir <- parent.env(envir)
+    }
+    # View has already evaluated its argument; rebuilding an active root would
+    # evaluate it again and could display a different value.
+    if (identical(envir, emptyenv()) || bindingIsActive(name, envir)) return(NULL)
+    root <- listview_state(get(name, envir = envir, inherits = FALSE), name, owner)
     listview_context(root, selectors)
   }, error = function(e) NULL)
 }
diff --git a/sess/inst/tinytest/test-listview.R b/sess/inst/tinytest/test-listview.R
index d41db1eb9..89ea2f26e 100644
--- a/sess/inst/tinytest/test-listview.R
+++ b/sess/inst/tinytest/test-listview.R
@@ -146,6 +146,35 @@ local({
   direct_context <- sess:::listview_expression_context(quote(x$a$b), environment(), "x")
   expect_equal(direct_context$navigation$path, list(1L, 1L), check.attributes = FALSE)
   expect_equal(direct_context$navigation$title, "x$a$b")
+
+  # Active roots are evaluated once, including when inherited by the caller.
+  for (inherited in c(FALSE, TRUE)) {
+    calls <- 0L
+    evaluated <- NULL
+    binding_env <- new.env(parent = environment())
+    makeActiveBinding("active_root", function() {
+      calls <<- calls + 1L
+      evaluated <<- list(nested = list(value = c(calls, calls + 10L)))
+      evaluated
+    }, binding_env)
+    caller <- if (inherited) new.env(parent = binding_env) else binding_env
+    expressions <- c("active_root", "active_root$nested", "active_root$nested$value")
+    for (expression in expressions) {
+      calls <- 0L
+      eval(parse(text = paste0("utils::View(", expression, ")")), caller)
+      read_messages()
+      expect_identical(calls, 1L)
+      expected <- switch(expression,
+        active_root = evaluated,
+        "active_root$nested" = evaluated$nested,
+        "active_root$nested$value" = evaluated$nested$value
+      )
+      expect_identical(runtime$dataviews[[id("list", "active_root")]]$data, expected)
+      expect_equal(notification()$navigation$title, expression)
+      expect_length(notification()$navigation$breadcrumbs, 1L)
+    }
+  }
+
   utils::View(x$df)
   direct_table <- id("table", "x")
   utils::View(x$a$df)

From 7582cc911e6b6fcaf78ea00b18cb02db1b2d0338 Mon Sep 17 00:00:00 2001
From: "4111978+Fred-Wu@users.noreply.github.com"
 <4111978+Fred-Wu@users.noreply.github.com>
Date: Sun, 4 Oct 2026 14:14:37 +1100
Subject: [PATCH 15/30] fix(viewer): preserve custom extraction semantics

---
 sess/R/handlers.R                  |  70 +++++++++++++----
 sess/R/hooks.R                     |   2 +-
 sess/inst/tinytest/test-listview.R | 118 ++++++++++++++++++++++++++++-
 3 files changed, 172 insertions(+), 18 deletions(-)

diff --git a/sess/R/handlers.R b/sess/R/handlers.R
index e303ab327..726b09b53 100644
--- a/sess/R/handlers.R
+++ b/sess/R/handlers.R
@@ -182,35 +182,66 @@ listview_state <- function(object, title, owner) {
 }
 
 # Resolve workspace selectors once; navigation paths are relative to the retained root.
-listview_context <- function(root, selectors) {
-  location <- listview_location(root, selectors, resolve_selectors = TRUE)
+listview_context <- function(root, selectors, expression_env = NULL) {
+  location <- listview_location(
+    root, selectors, resolve_selectors = TRUE, expression_env = expression_env
+  )
   list(root = root, data = location$data, navigation = listview_navigation(location))
 }
 
+# Read a binding without invoking an active binding for a second time.
+listview_binding <- function(name, envir) {
+  while (!identical(envir, emptyenv()) && !exists(name, envir = envir, inherits = FALSE)) {
+    envir <- parent.env(envir)
+  }
+  if (identical(envir, emptyenv()) || bindingIsActive(name, envir)) return(NULL)
+  get(name, envir = envir, inherits = FALSE)
+}
+
+# Only known structural extraction can be represented by an index breadcrumb.
+listview_structural_extraction <- function(object, operator, envir) {
+  if (operator == "@") return(isS4(object))
+  if (!is.object(object)) return(TRUE)
+  if (isS4(object) || !identical(class(object), "data.frame")) return(FALSE)
+  if (operator == "$" &&
+        !is.null(utils::getS3method("$", "data.frame", optional = TRUE, envir = envir))) {
+    return(FALSE)
+  }
+  # Check both the caller's extraction and the viewer's later indexed traversal.
+  all(vapply(list(envir, environment(listview_location)), function(method_env) {
+    identical(utils::getS3method("[[", "data.frame", optional = TRUE, envir = method_env),
+              base::`[[.data.frame`)
+  }, logical(1)))
+}
+
 # Direct View(x$a) calls can also start with a complete breadcrumb path.
-listview_expression_context <- function(expression, envir, owner) {
+listview_expression_context <- function(expression, envir, owner, value) {
   tryCatch({
     selectors <- list()
     while (is.call(expression) && length(expression) == 3L &&
              is.symbol(expression[[1L]])) {
       operator <- as.character(expression[[1L]])
       if (!operator %in% c("$", "[[", "@")) return(NULL)
-      value <- expression[[3L]]
-      if (operator %in% c("$", "@") && is.symbol(value)) value <- as.character(value)
-      if (length(value) != 1L || !(is.character(value) || is.numeric(value))) return(NULL)
-      selectors <- c(list(list(kind = "index", value = value)), selectors)
+      if (!identical(listview_binding(operator, envir), get(operator, envir = baseenv()))) {
+        return(NULL)
+      }
+      selector <- expression[[3L]]
+      if (operator %in% c("$", "@") && is.symbol(selector)) selector <- as.character(selector)
+      if (length(selector) != 1L || !(is.character(selector) || is.numeric(selector))) return(NULL)
+      selectors <- c(list(list(kind = operator, value = selector)), selectors)
       expression <- expression[[2L]]
     }
     if (!length(selectors) || !is.symbol(expression)) return(NULL)
     name <- as.character(expression)
-    while (!identical(envir, emptyenv()) && !exists(name, envir = envir, inherits = FALSE)) {
-      envir <- parent.env(envir)
+    object <- listview_binding(name, envir)
+    if (is.null(object) || !listview_structural_extraction(object, selectors[[1L]]$kind, envir)) {
+      return(NULL)
     }
-    # View has already evaluated its argument; rebuilding an active root would
-    # evaluate it again and could display a different value.
-    if (identical(envir, emptyenv()) || bindingIsActive(name, envir)) return(NULL)
-    root <- listview_state(get(name, envir = envir, inherits = FALSE), name, owner)
-    listview_context(root, selectors)
+    root <- listview_state(object, name, owner)
+    context <- listview_context(root, selectors, expression_env = envir)
+    # Even a safe path is optional: the already-evaluated argument is authoritative.
+    if (!identical(context$data, value)) return(NULL)
+    context
   }, error = function(e) NULL)
 }
 
@@ -236,13 +267,20 @@ handle_listview_navigate <- function(view_id, path = list()) {
   listview_navigation(location)
 }
 
-listview_location <- function(state, path = list(), resolve_selectors = FALSE) {
+listview_location <- function(state, path = list(), resolve_selectors = FALSE,
+                              expression_env = NULL) {
   visited <- integer()
   state$breadcrumbs <- list(list(label = state$title, path = I(list())))
   for (index in path) {
     if (resolve_selectors) {
-      index <- if (index$kind == "index" && is.numeric(index$value)) {
+      if (!is.null(expression_env) &&
+            !listview_structural_extraction(state$data, index$kind, expression_env)) {
+        stop("Cannot reconstruct custom extraction as an index path")
+      }
+      index <- if (index$kind %in% c("index", "[[") && is.numeric(index$value)) {
         index$value
+      } else if (index$kind == "$" && state$kind == "index") {
+        pmatch(index$value, state$names, duplicates.ok = TRUE)
       } else {
         match(index$value, state$names)
       }
diff --git a/sess/R/hooks.R b/sess/R/hooks.R
index 45ea5533c..569621944 100644
--- a/sess/R/hooks.R
+++ b/sess/R/hooks.R
@@ -154,7 +154,7 @@ runtime_start <- function(use_rstudioapi = TRUE,
     } else if (view_type == "list") {
       context <- .sess_env$listview_context
       if (is.null(context) && missing(title)) {
-        context <- listview_expression_context(original_expression, parent.frame(), owner)
+        context <- listview_expression_context(original_expression, parent.frame(), owner, x)
       }
       root <- if (is.null(context)) listview_state(x, title_key, owner) else context$root
       navigation <- if (is.null(context)) {
diff --git a/sess/inst/tinytest/test-listview.R b/sess/inst/tinytest/test-listview.R
index 89ea2f26e..71747a504 100644
--- a/sess/inst/tinytest/test-listview.R
+++ b/sess/inst/tinytest/test-listview.R
@@ -143,9 +143,14 @@ local({
   expect_identical(runtime$dataviews[[direct_id]]$data, x)
   utils::View(x$a$b)
   expect_identical(runtime$dataviews[[direct_id]]$data, x)
-  direct_context <- sess:::listview_expression_context(quote(x$a$b), environment(), "x")
+  direct_context <- sess:::listview_expression_context(quote(x$a$b), environment(), "x", x$a$b)
   expect_equal(direct_context$navigation$path, list(1L, 1L), check.attributes = FALSE)
   expect_equal(direct_context$navigation$title, "x$a$b")
+  indexed_context <- sess:::listview_expression_context(
+    quote(x[[1L]][[1L]]), environment(), "x", x$a$b
+  )
+  expect_identical(indexed_context$data, x$a$b)
+  expect_equal(indexed_context$navigation$path, list(1L, 1L), check.attributes = FALSE)
 
   # Active roots are evaluated once, including when inherited by the caller.
   for (inherited in c(FALSE, TRUE)) {
@@ -175,6 +180,117 @@ local({
     }
   }
 
+  # Custom $ extraction can differ from the indexed path used by breadcrumbs.
+  dollar_calls <- 0L
+  `$.listview_custom` <- function(object, name) {
+    dollar_calls <<- dollar_calls + 1L
+    custom_value
+  }
+  index_calls <- 0L
+  `[[.listview_custom` <- function(object, index) {
+    index_calls <<- index_calls + 1L
+    unclass(object)[[index]]
+  }
+  # Register the method so dispatch inside the package can find it too.
+  registerS3method("[[", "listview_custom", `[[.listview_custom`, envir = asNamespace("base"))
+  on.exit({
+    rm("[[.listview_custom", envir = get(".__S3MethodsTable__.", asNamespace("base")))
+  }, add = TRUE)
+  custom <- structure(list(a = c(1L, 2L)), class = "listview_custom")
+  outer <- list(custom = custom)
+  for (custom_value in list(c(90L, 91L), list(returned = c(90L, 91L)))) {
+    for (expression in c("custom$a", "outer$custom$a")) {
+      dollar_calls <- 0L
+      index_calls <- 0L
+      eval(parse(text = paste0("utils::View(", expression, ")")))
+      read_messages()
+      expect_identical(dollar_calls, 1L)
+      expect_null(sess:::listview_expression_context(
+        parse(text = expression)[[1L]], environment(), "custom", custom_value
+      ))
+      expect_identical(index_calls, 0L)
+      view_id <- notification()$view_id
+      expect_identical(runtime$dataviews[[view_id]]$data, custom_value)
+      expect_equal(notification()$navigation$title, expression)
+      expect_length(notification()$navigation$breadcrumbs, 1L)
+      expect_length(notification()$navigation$path, 0L)
+      page <- sess:::get_workspace_children(view_id = view_id)
+      if (is.atomic(custom_value)) {
+        expect_equal(vapply(page$children, `[[`, "", "str"), c("90", "91"))
+      } else {
+        expect_equal(page$children[[1L]]$label, "$ returned")
+      }
+    }
+  }
+
+  index_calls <- 0L
+  utils::View(custom[["a"]])
+  read_messages()
+  expect_identical(index_calls, 1L)
+  expect_identical(runtime$dataviews[[notification()$view_id]]$data, c(1L, 2L))
+
+  # A locally rebound operator changes extraction even for an ordinary list.
+  for (operator in c("$", "[[", "@")) {
+    for (active in c(FALSE, TRUE)) {
+      caller <- new.env(parent = environment())
+      caller$x <- list(a = c(1L, 2L))
+      extraction_calls <- 0L
+      binding_calls <- 0L
+      extraction <- function(object, name) {
+        extraction_calls <<- extraction_calls + 1L
+        c(90L, 91L)
+      }
+      if (active) {
+        makeActiveBinding(operator, function() {
+          binding_calls <<- binding_calls + 1L
+          extraction
+        }, caller)
+      } else {
+        assign(operator, extraction, envir = caller)
+      }
+      expression <- switch(operator, "$" = "x$a", "[[" = "x[[1L]]", "@" = "x@a")
+      eval(parse(text = paste0("utils::View(", expression, ")")), caller)
+      read_messages()
+      expect_identical(extraction_calls, 1L)
+      expect_identical(binding_calls, if (active) 1L else 0L)
+      expect_identical(runtime$dataviews[[notification()$view_id]]$data, c(90L, 91L))
+      expect_length(notification()$navigation$path, 0L)
+    }
+  }
+
+  # Standard data-frame columns retain their parent navigation.
+  frame <- data.frame(values = 1:2)
+  for (expression in c("frame$values", "frame$val", "frame[[1L]]", "frame[['values']]")) {
+    eval(parse(text = paste0("utils::View(", expression, ")")))
+    read_messages()
+    expect_identical(runtime$dataviews[[notification()$view_id]]$data, frame)
+    expect_equal(notification()$navigation$path, list(1L))
+    expect_equal(vapply(notification()$navigation$breadcrumbs, `[[`, "", "label"),
+                 c("frame", "values"))
+  }
+
+  # Local S3 overrides of standard data-frame extraction must also run only once.
+  for (operator in c("$", "[[")) {
+    caller <- new.env(parent = environment())
+    caller$frame <- frame
+    extraction_calls <- 0L
+    assign(paste0(operator, ".data.frame"), function(object, name) {
+      extraction_calls <<- extraction_calls + 1L
+      c(90L, 91L)
+    }, envir = caller)
+    expression <- if (operator == "$") "frame$values" else "frame[[1L]]"
+    eval(parse(text = paste0("utils::View(", expression, ")")), caller)
+    read_messages()
+    expect_identical(extraction_calls, 1L)
+    expect_identical(runtime$dataviews[[notification()$view_id]]$data, c(90L, 91L))
+    expect_length(notification()$navigation$path, 0L)
+  }
+
+  # A structural path must not replace an already-evaluated, different value.
+  expect_null(sess:::listview_expression_context(
+    quote(x$a$b), environment(), "x", list(other = 1L)
+  ))
+
   utils::View(x$df)
   direct_table <- id("table", "x")
   utils::View(x$a$df)

From 6647d3f3bef29f5aa09fce843c105b70c8985b42 Mon Sep 17 00:00:00 2001
From: "4111978+Fred-Wu@users.noreply.github.com"
 <4111978+Fred-Wu@users.noreply.github.com>
Date: Sun, 4 Oct 2026 20:42:14 +1100
Subject: [PATCH 16/30] fix(viewer): preserve names for named vectors while
 empty or missing names retain [index] labels.

---
 sess/R/handlers.R                  |  6 +++++-
 sess/inst/tinytest/test-listview.R | 26 ++++++++++++++++++++++++++
 src/test/suite/listViewer.test.ts  | 22 +++++++++++++---------
 3 files changed, 44 insertions(+), 10 deletions(-)

diff --git a/sess/R/handlers.R b/sess/R/handlers.R
index 726b09b53..a53609bbf 100644
--- a/sess/R/handlers.R
+++ b/sess/R/handlers.R
@@ -376,7 +376,11 @@ get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_
     children <- lapply(seq.int(start, end), function(index) {
       child_name <- if (is.null(child_names)) NULL else child_names[[index]]
       label <- if (vector_rows) {
-        paste0("[", index, "]")
+        if (!is.null(child_name) && !is.na(child_name) && nzchar(child_name)) {
+          child_name
+        } else {
+          paste0("[", index, "]")
+        }
       } else if (kind == "slot") {
         paste0("@ ", child_name)
       } else {
diff --git a/sess/inst/tinytest/test-listview.R b/sess/inst/tinytest/test-listview.R
index 71747a504..0b560d6cb 100644
--- a/sess/inst/tinytest/test-listview.R
+++ b/sess/inst/tinytest/test-listview.R
@@ -311,6 +311,32 @@ local({
   expect_equal(last_vector_page$children[[1L]]$label, "[501]")
   expect_equal(last_vector_page$children[[1L]]$str, "501")
 
+  # Named vectors retain names, duplicates and positions across page boundaries.
+  named_values <- seq_len(501L)
+  names(named_values) <- rep("", length(named_values))
+  names(named_values)[c(1L, 3L, 4L, 5L, 6L, 7L, 501L)] <-
+    c("first", "first", NA, "a b", "", "\u540d\u524d", "last")
+  named_root <- list(values = named_values)
+  for (expression in c("named_values", "named_root$values")) {
+    eval(parse(text = paste0("utils::View(", expression, ")")))
+    read_messages()
+    params <- list(view_id = notification()$view_id, path = notification()$navigation$path)
+    page <- do.call(sess:::get_workspace_children, params)
+    expect_equal(vapply(page$children[seq_len(7L)], `[[`, "", "label"),
+                 c("first", "[2]", "first", "[4]", "a b", "", "\u540d\u524d"))
+    expect_equal(vapply(page$children[seq_len(7L)], `[[`, "", "str"), as.character(seq_len(7L)))
+    expect_equal(vapply(page$children, `[[`, 0L, "index"), seq_len(500L))
+    expect_false(any(vapply(page$children, `[[`, FALSE, "has_children")))
+    expect_false(any(vapply(page$children, `[[`, FALSE, "viewable")))
+    expect_equal(page$next_start, 501L)
+    params$start <- page$next_start
+    last <- request("workspace_children", params)
+    expect_equal(last$children[[1L]]$label, "last")
+    expect_equal(last$children[[1L]]$str, "501")
+    expect_equal(last$children[[1L]]$index, 501L)
+    expect_null(last$next_start)
+  }
+
   utils::View(x$a$b$value)
   text_id <- id("object", "x")
   text_file <- runtime$dataviews[[text_id]]$file
diff --git a/src/test/suite/listViewer.test.ts b/src/test/suite/listViewer.test.ts
index 06d9ef815..d0e9e6ace 100644
--- a/src/test/suite/listViewer.test.ts
+++ b/src/test/suite/listViewer.test.ts
@@ -210,21 +210,25 @@ suite('List viewer', () => {
         assert.strictEqual(secondPage.children[1].hidden, true);
     });
 
-    test('renders vector values as simple indexed rows', () => {
+    test('renders named and unnamed vector rows as plain text', () => {
         const viewer = createViewer({
             title: 'x', path: [], breadcrumbs: [{ label: 'x', path: [] }], vector: true,
         });
+        const labels = ['first', '[2]', 'first', '', 'a b'];
         viewer.reply(viewer.messages[0], {
-            children: [{
-                label: '[1]', str: '12.4', index: 1,
+            children: labels.map((label, index) => ({
+                label, str: '12.4', index: index + 1,
                 viewable: false, has_children: false,
-            }],
+            })),
+        });
+        labels.forEach((label, index) => {
+            const row = viewer.root.children[0].children[index].children[0];
+            assert.deepStrictEqual(row.children.map(child => child.className), ['label', 'str']);
+            assert.strictEqual(row.children[0].textContent, label);
+            assert.strictEqual(row.children[0].innerHTML, '');
+            assert.strictEqual(row.children[1].textContent, '12.4');
+            assert.ok(!row.children.some(child => child.tag === 'button'));
         });
-        const row = viewer.root.children[0].children[0].children[0];
-        assert.deepStrictEqual(row.children.map(child => child.className), ['label', 'str']);
-        assert.strictEqual(row.children[0].textContent, '[1]');
-        assert.strictEqual(row.children[1].textContent, '12.4');
-        assert.ok(!row.children.some(child => child.tag === 'button'));
     });
 
     test('vectors share list navigation, Back and cached pages, including late page responses', () => {

From 89adf4ff9bfec734bd21a7d7a8873d2ba8b4b918 Mon Sep 17 00:00:00 2001
From: "4111978+Fred-Wu@users.noreply.github.com"
 <4111978+Fred-Wu@users.noreply.github.com>
Date: Sun, 4 Oct 2026 21:32:04 +1100
Subject: [PATCH 17/30] fix(viewer):  - reuse data viewer formatting for list
 and vector values  - route scalar value to the shared list viewer for
 consistency

---
 sess/R/handlers.R                         |  64 +++++++++---
 sess/inst/tinytest/test-listview-format.R | 113 ++++++++++++++++++++++
 sess/inst/tinytest/test-listview.R        |  58 ++++++++++-
 3 files changed, 219 insertions(+), 16 deletions(-)
 create mode 100644 sess/inst/tinytest/test-listview-format.R

diff --git a/sess/R/handlers.R b/sess/R/handlers.R
index a53609bbf..6a658ef02 100644
--- a/sess/R/handlers.R
+++ b/sess/R/handlers.R
@@ -160,12 +160,11 @@ handle_workspace_view <- function(name, path = list()) {
 listview_supported <- function(object) {
   !dataview_is_table(object) &&
     (is.list(object) || is.pairlist(object) || is.environment(object) || isS4(object) ||
-       (is.atomic(object) && length(object) > 1L))
+       listview_is_vector(object))
 }
 
 listview_is_vector <- function(object) {
-  !dataview_is_table(object) &&
-    (inherits(object, "POSIXlt") || (!isS4(object) && is.atomic(object) && length(object) > 1L))
+  !dataview_is_table(object) && (is.atomic(object) || inherits(object, "POSIXlt"))
 }
 
 listview_state <- function(object, title, owner) {
@@ -338,6 +337,50 @@ listview_location <- function(state, path = list(), resolve_selectors = FALSE,
   state
 }
 
+listview_format_values <- function(values) {
+  # Format before extracting individual elements, which may discard their class.
+  formatted <- dataview_format_column(values)
+  if (is.character(values) && !is.object(values)) {
+    return(encodeString(formatted, quote = "\"", na.encode = TRUE))
+  }
+  if (is.numeric(formatted) && !is.object(formatted)) {
+    # Match the numeric precision sent to the data viewer over IPC.
+    formatted <- vapply(formatted, function(value) {
+      if (is.finite(value)) {
+        as.character(jsonlite::toJSON(value, auto_unbox = TRUE, digits = NA))
+      } else {
+        as.character(value)
+      }
+    }, character(1))
+  } else if (!is.character(formatted)) {
+    formatted <- format(formatted, trim = TRUE, justify = "none")
+  }
+  formatted[is.na(formatted)] <- "NA"
+  formatted
+}
+
+listview_summary <- function(object) {
+  if (is.atomic(object) || inherits(object, "POSIXlt")) {
+    size <- length(object)
+    type <- if (is.object(object)) {
+      paste(class(object), collapse = "/")
+    } else {
+      switch(typeof(object), integer = "int", double = "num", complex = "cplx",
+             logical = "logi", character = "chr", raw = "raw")
+    }
+    if (!size) return(paste0(type, "(0)"))
+    shape <- if (!is.null(dim(object))) {
+      paste0(" [", paste0("1:", dim(object), collapse = ", "), "]")
+    } else if (size > 1L) {
+      paste0(" [1:", size, "]")
+    }
+    paste0(type, shape, " ",
+           listview_format_values(object[1L]), if (size > 1L) " ...")
+  } else {
+    trimws(try_capture_str(object))
+  }
+}
+
 get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_id = NULL) {
   tryCatch({
     vector_rows <- FALSE
@@ -355,8 +398,8 @@ get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_
       state <- listview_location(state, path)
       object <- state$data
       vector_rows <- listview_is_vector(object)
-      kind <- state$kind
-      child_names <- state$names
+      kind <- if (vector_rows) "index" else state$kind
+      child_names <- if (vector_rows) names(object) else state$names
     }
     child_count <- if (kind == "index") {
       if (vector_rows) {
@@ -372,6 +415,7 @@ get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_
     if (start > end) {
       return(list(children = I(list()), next_start = NULL))
     }
+    formatted_values <- if (vector_rows) listview_format_values(object[seq.int(start, end)])
 
     children <- lapply(seq.int(start, end), function(index) {
       child_name <- if (is.null(child_names)) NULL else child_names[[index]]
@@ -403,19 +447,15 @@ get_workspace_children <- function(name = NULL, path = list(), start = 1L, view_
           type = unavailable, has_children = FALSE
         ))
       }
-      child <- switch(kind,
+      child <- if (!vector_rows) switch(kind,
         name = get(child_name, envir = object, inherits = FALSE),
         slot = methods::slot(object, child_name),
         index = object[[index]]
       )
       summary <- if (vector_rows) {
-        if (is.character(child)) {
-          encodeString(child, quote = "\"", na.encode = TRUE)
-        } else {
-          paste(format(child, trim = TRUE), collapse = " ")
-        }
+        formatted_values[[index - start + 1L]]
       } else {
-        trimws(try_capture_str(child))
+        listview_summary(child)
       }
       if (!is.null(view_id)) {
         list(
diff --git a/sess/inst/tinytest/test-listview-format.R b/sess/inst/tinytest/test-listview-format.R
new file mode 100644
index 000000000..56f257c18
--- /dev/null
+++ b/sess/inst/tinytest/test-listview-format.R
@@ -0,0 +1,113 @@
+# List rows use the same class formatting and numeric precision as table cells.
+local({
+  runtime <- sess:::.sess_env
+  previous <- runtime$dataviews
+  previous_options <- options(digits = 3L)
+  on.exit({
+    runtime$dataviews <- previous
+    options(previous_options)
+  }, add = TRUE)
+  page <- function(object, path = list(), start = 1L) {
+    runtime$dataviews$format_test <- sess:::listview_state(object, "x", "x")
+    sess:::get_workspace_children(view_id = "format_test", path = path, start = start)
+  }
+  text <- function(page) vapply(page$children, `[[`, "", "str")
+
+  numbers <- c(1.23456789012345, 1.54e-100, -6.65e-13, 1.23456789012345e14,
+               0, NA_real_, NaN, Inf, -Inf)
+  expected <- c("1.23456789012345", "1.54e-100", "-6.65e-13", "123456789012345",
+                "0", "NA", "NaN", "Inf", "-Inf")
+  expect_equal(text(page(numbers)), expected)
+  expect_equal(text(page(list(nested = numbers), list(1L))), expected)
+  expect_equal(text(page(as.list(numbers))), paste("num", expected))
+  for (index in seq_along(numbers)) {
+    expect_true(sess:::listview_supported(numbers[index]))
+    expect_true(sess:::listview_is_vector(numbers[index]))
+    expect_equal(text(page(numbers[index])), expected[index])
+    expect_false(page(numbers[index])$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(matrix(rep(numbers[[1L]], 4L), nrow = 2L)))),
+               paste0("num [1:2, 1:2] ", expected[[1L]], " ..."))
+  expect_identical(numbers, c(
+    1.23456789012345, 1.54e-100, -6.65e-13, 1.23456789012345e14, 0, NA_real_, NaN, Inf, -Inf
+  ))
+  expect_equal(text(page(c("001", NA_character_))), c('"001"', "NA"))
+
+  registerS3method("[", "listview_number", function(x, ...) {
+    structure(NextMethod(), class = class(x), unit = attr(x, "unit"))
+  })
+  registerS3method("format", "listview_number", function(x, ...) {
+    paste0(attr(x, "unit"), ":", sprintf("%.9f", as.numeric(x)))
+  })
+  registerS3method("[", "listview_label", function(x, ...) {
+    structure(NextMethod(), class = class(x))
+  })
+  registerS3method("format", "listview_label", function(x, ...) {
+    paste0("ID:", as.character(x))
+  })
+  class_env <- environment()
+  methods::setClass("listview_s4_number", contains = "numeric", where = class_env)
+  methods::setMethod("[", "listview_s4_number", function(x, i, j, ..., drop = TRUE) {
+    methods::new("listview_s4_number", as.numeric(x)[i])
+  }, where = class_env)
+  registerS3method("format", "listview_s4_number", function(x, ...) {
+    paste0("S4:", sprintf("%.9f", as.numeric(x)))
+  })
+  on.exit({
+    methods::removeMethod("[", "listview_s4_number", where = class_env)
+    methods::removeClass("listview_s4_number", where = class_env)
+    rm(list = c("[.listview_number", "format.listview_number", "format.listview_s4_number",
+                "[.listview_label", "format.listview_label"),
+       envir = get(".__S3MethodsTable__.", asNamespace("base")))
+  }, add = TRUE)
+
+  cases <- list(
+    S3 = structure(c(1.234567891, NA_real_), class = "listview_number", unit = "USD"),
+    S4 = methods::new("listview_s4_number", c(1.234567891, NA_real_)),
+    difftime = as.difftime(c(60, NA), units = "secs"),
+    factor = factor(c("first", NA)),
+    date = as.Date(c("2026-01-01", NA)),
+    character_class = structure(c("001", NA_character_), class = "listview_label"),
+    complex = c(1 + 2i, NA_complex_)
+  )
+  if (requireNamespace("bit64", quietly = TRUE)) {
+    cases$integer64 <- bit64::as.integer64(c("9007199254740993", NA))
+  }
+  for (name in names(cases)) {
+    values <- cases[[name]]
+    original <- serialize(values, NULL)
+    table <- data.frame(id = seq_along(values))
+    table$value <- values
+    table_text <- as.character(sess:::dataview_rows(
+      sess:::dataview_to_state(table), seq_along(values)
+    )[["2"]])
+    table_text[is.na(table_text)] <- "NA"
+    expect_equal(text(page(values)), table_text, info = name)
+    expect_equal(text(page(list(value = values), list(1L))), table_text, info = name)
+    expect_true(grepl(table_text[[1L]], text(page(list(values[1L])))[[1L]], fixed = TRUE),
+                info = name)
+    expect_identical(serialize(values, NULL), original, info = name)
+    scalar <- values[1L]
+    expect_true(sess:::listview_supported(scalar), info = name)
+    expect_true(sess:::listview_is_vector(scalar), info = name)
+    expect_equal(text(page(scalar)), table_text[1L], info = name)
+    page(list(value = scalar))
+    navigation <- sess:::handle_listview_view("format_test", 1L)
+    expect_true(navigation$vector, info = name)
+    expect_equal(navigation$path, list(1L), check.attributes = FALSE, info = name)
+    expect_false(page(scalar)$children[[1L]]$has_children, info = name)
+    expect_false(page(scalar)$children[[1L]]$viewable, info = name)
+  }
+
+  values <- structure(rep(1.234567891, 501L), class = "listview_number", unit = "USD")
+  names(values) <- paste0("item", seq_along(values))
+  first <- page(values)
+  last <- page(values, start = 501L)
+  expect_length(first$children, 500L)
+  expect_equal(first$next_start, 501L)
+  expect_equal(unique(text(first)), "USD:1.234567891")
+  expect_equal(text(last), "USD:1.234567891")
+  expect_equal(last$children[[1L]]$label, "item501")
+})
diff --git a/sess/inst/tinytest/test-listview.R b/sess/inst/tinytest/test-listview.R
index 0b560d6cb..2098e3a05 100644
--- a/sess/inst/tinytest/test-listview.R
+++ b/sess/inst/tinytest/test-listview.R
@@ -338,12 +338,62 @@ local({
   }
 
   utils::View(x$a$b$value)
-  text_id <- id("object", "x")
-  text_file <- runtime$dataviews[[text_id]]$file
+  read_messages()
+  expect_equal(notification()$view_id, direct_id)
+  expect_true(notification()$navigation$vector)
+  expect_equal(notification()$navigation$path, list(1L, 1L, 1L))
+  scalar_page <- request("workspace_children", list(
+    view_id = direct_id, path = list(1L, 1L, 1L)
+  ))
+  expect_length(scalar_page$children, 1L)
+  expect_equal(scalar_page$children[[1L]]$str, "1")
   utils::View(x$a$df$nested)
-  expect_identical(id("object", "x"), text_id)
+  read_messages()
+  expect_equal(notification()$view_id, direct_id)
+  expect_true(notification()$navigation$vector)
+  expect_equal(notification()$navigation$path, list(1L, 2L, 1L))
+  navigation <- request("listview_view", list(view_id = direct_id, path = list(1L, 1L), index = 1L))
+  expect_true(navigation$vector)
+  expect_equal(navigation$path, list(1L, 1L, 1L))
+  expect_length(notifications, 0L)
+
+  # Scalars use the vector formatting route regardless of storage type or class.
+  for (sample in list(difftime(1, 2, units = "mins"), as.Date("2026-01-01"),
+                      as.POSIXct("2026-01-01 12:34:56", tz = "UTC"), factor("ready"),
+                      TRUE, "001", as.raw(255))) {
+    utils::View(sample, title = "scalar")
+    read_messages()
+    expect_equal(notification()$source, "list")
+    expect_true(notification()$navigation$vector)
+    scalar_page <- request("workspace_children", list(view_id = notification()$view_id))
+    expect_length(scalar_page$children, 1L)
+    expected <- if (is.character(sample)) {
+      encodeString(sample, quote = "\"")
+    } else {
+      format(sample, trim = TRUE, justify = "none")
+    }
+    expect_equal(scalar_page$children[[1L]]$str, expected)
+    expect_false(scalar_page$children[[1L]]$has_children)
+    expect_false(scalar_page$children[[1L]]$viewable)
+  }
+
+  for (sample in list(numeric(), character(), logical(), raw())) {
+    utils::View(sample, title = "empty vector")
+    read_messages()
+    expect_equal(notification()$source, "list")
+    expect_true(notification()$navigation$vector)
+    empty_page <- request("workspace_children", list(view_id = notification()$view_id))
+    expect_length(empty_page$children, 0L)
+  }
+
+  functions <- list(first = function() 1L, second = function() 2L)
+  utils::View(functions$first)
+  text_id <- id("object", "functions")
+  text_file <- runtime$dataviews[[text_id]]$file
+  utils::View(functions$second)
+  expect_identical(id("object", "functions"), text_id)
   expect_identical(runtime$dataviews[[text_id]]$file, text_file)
-  expect_equal(readLines(text_file), "2L")
+  expect_equal(readLines(text_file), deparse(functions$second))
   unlink(text_file)
 
   # Vectors opened from expanded list rows retain the root and every breadcrumb.

From 65ca4872a5a1fe55b625d4690a29a4c562fa8b83 Mon Sep 17 00:00:00 2001
From: Fred-Wu <4111978+Fred-Wu@users.noreply.github.com>
Date: Sun, 4 Oct 2026 23:07:20 +1100
Subject: [PATCH 18/30] fix(viewer): prevent stale disposal from deleting
 reopened viewer state

---
 sess/R/handlers.R                         | 15 ++++++--
 sess/R/hooks.R                            |  6 ++--
 sess/inst/tinytest/test-dataview.R        | 43 +++++++++++++++++++++++
 sess/inst/tinytest/test-listview.R        |  6 ++--
 src/session.ts                            | 25 ++++++++++---
 src/test/suite/dataViewerSessions.test.ts | 16 ++++++---
 6 files changed, 95 insertions(+), 16 deletions(-)

diff --git a/sess/R/handlers.R b/sess/R/handlers.R
index 6a658ef02..bf81338d3 100644
--- a/sess/R/handlers.R
+++ b/sess/R/handlers.R
@@ -804,11 +804,16 @@ dataview_new_id <- function() {
   }
 }
 
-dataview_register <- function(data, view_id = NULL, live = FALSE) {
+dataview_set_state <- function(view_id, state) {
   if (is.null(.sess_env$dataviews)) {
     .sess_env$dataviews <- list()
   }
+  state$instance <- (.sess_env$dataviews[[view_id]]$instance %||% 0L) + 1L
+  .sess_env$dataviews[[view_id]] <- state
+  state
+}
 
+dataview_register <- function(data, view_id = NULL, live = FALSE) {
   if (is.null(view_id)) {
     view_id <- dataview_new_id()
   }
@@ -816,9 +821,10 @@ dataview_register <- function(data, view_id = NULL, live = FALSE) {
   state <- dataview_to_state(data)
   state$live <- live
   state$revision <- .sess_env$dataview_revision %||% 0
-  .sess_env$dataviews[[view_id]] <- state
+  state <- dataview_set_state(view_id, state)
   list(
     view_id = view_id,
+    instance = state$instance,
     total_rows = state$total_rows,
     columns = dataview_columns(state)
   )
@@ -839,6 +845,7 @@ dataview_get_state <- function(view_id, refresh = FALSE) {
           !identical(state$total_rows, current$total_rows)) {
       current$live <- TRUE
       current$revision <- revision
+      current$instance <- state$instance
       state <- current
       .sess_env$dataviews[[view_id]] <- state
     }
@@ -1268,7 +1275,9 @@ handle_dataview_page <- function(params) {
 
 handle_dataview_dispose <- function(params) {
   view_id <- as.character(params$view_id %||% "")
-  if (!is.null(.sess_env$dataviews) && !is.null(.sess_env$dataviews[[view_id]])) {
+  state <- if (is.null(.sess_env$dataviews)) NULL else .sess_env$dataviews[[view_id]]
+  instance <- suppressWarnings(as.integer(params$instance %||% NA_integer_))
+  if (!is.null(state) && identical(state$instance, instance)) {
     .sess_env$dataviews[[view_id]] <- NULL
   }
   TRUE
diff --git a/sess/R/hooks.R b/sess/R/hooks.R
index 569621944..7a2081a3d 100644
--- a/sess/R/hooks.R
+++ b/sess/R/hooks.R
@@ -149,7 +149,8 @@ runtime_start <- function(use_rstudioapi = TRUE,
         title = title,
         source = "table",
         type = "json",
-        view_id = registration$view_id
+        view_id = registration$view_id,
+        instance = registration$instance
       ))
     } else if (view_type == "list") {
       context <- .sess_env$listview_context
@@ -162,12 +163,13 @@ runtime_start <- function(use_rstudioapi = TRUE,
       } else {
         context$navigation
       }
-      .sess_env$dataviews[[view_id]] <- root
+      root <- dataview_set_state(view_id, root)
       notify_client("dataview", list(
         title = title,
         source = view_type,
         type = "json",
         view_id = view_id,
+        instance = root$instance,
         navigation = navigation
       ))
     } else {
diff --git a/sess/inst/tinytest/test-dataview.R b/sess/inst/tinytest/test-dataview.R
index 977121b47..b4d464b44 100644
--- a/sess/inst/tinytest/test-dataview.R
+++ b/sess/inst/tinytest/test-dataview.R
@@ -368,3 +368,46 @@ local({
   expect_false(last$children[[1L]]$viewable)
   expect_length(sess:::get_workspace_children(view_id = "paging_test", start = 502L)$children, 0L)
 })
+
+
+# A delayed panel close cannot dispose state recreated under the same viewer id.
+local({
+  runtime <- sess:::.sess_env
+  previous <- runtime$dataviews
+  on.exit(runtime$dataviews <- previous, add = TRUE)
+
+  cases <- list(
+    list = list(
+      first = sess:::listview_state(list(value = 1L), "x", "x"),
+      replacement = sess:::listview_state(list(value = 2L), "x", "x")
+    ),
+    table = list(
+      first = sess:::dataview_to_state(data.frame(value = 1L)),
+      replacement = sess:::dataview_to_state(data.frame(value = 2L))
+    )
+  )
+
+  for (name in names(cases)) {
+    runtime$dataviews <- list()
+    first <- sess:::dataview_set_state("replacement_test", cases[[name]]$first)
+    replacement <- sess:::dataview_set_state(
+      "replacement_test", cases[[name]]$replacement
+    )
+    expect_true(replacement$instance > first$instance, info = name)
+
+    expect_true(sess:::handle_dataview_dispose(list(
+      view_id = "replacement_test", instance = first$instance
+    )), info = name)
+    expect_identical(
+      runtime$dataviews$replacement_test$instance, replacement$instance, info = name
+    )
+    expect_identical(
+      runtime$dataviews$replacement_test$data, cases[[name]]$replacement$data, info = name
+    )
+
+    expect_true(sess:::handle_dataview_dispose(list(
+      view_id = "replacement_test", instance = replacement$instance
+    )), info = name)
+    expect_null(runtime$dataviews$replacement_test, info = name)
+  }
+})
diff --git a/sess/inst/tinytest/test-listview.R b/sess/inst/tinytest/test-listview.R
index 2098e3a05..3ae56614d 100644
--- a/sess/inst/tinytest/test-listview.R
+++ b/sess/inst/tinytest/test-listview.R
@@ -358,7 +358,7 @@ local({
   expect_length(notifications, 0L)
 
   # Scalars use the vector formatting route regardless of storage type or class.
-  for (sample in list(difftime(1, 2, units = "mins"), as.Date("2026-01-01"),
+  for (sample in list(as.difftime(1, units = "mins"), as.Date("2026-01-01"),
                       as.POSIXct("2026-01-01 12:34:56", tz = "UTC"), factor("ready"),
                       TRUE, "001", as.raw(255))) {
     utils::View(sample, title = "scalar")
@@ -478,7 +478,9 @@ local({
   expect_false(sess:::handle_listview_view(list_id, 0L))
   expect_false(sess:::handle_listview_view(list_id, 1.5))
   expect_false(sess:::handle_listview_view(list_id, 1L, list(99L)))
-  expect_true(sess:::handle_dataview_dispose(list(view_id = list_id)))
+  expect_true(sess:::handle_dataview_dispose(list(
+    view_id = list_id, instance = runtime$dataviews[[list_id]]$instance
+  )))
   expect_null(runtime$dataviews[[list_id]])
   sess:::handle_workspace_view(root)
   expect_identical(id("list"), list_id)
diff --git a/src/session.ts b/src/session.ts
index 821bbf4a2..c7f338544 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -220,6 +220,7 @@ interface DataViewRequestMessage {
 }
 
 const dynamicDataViewPanels = new Map();
+const dynamicDataViewInstances = new WeakMap();
 const listViewGenerations = new WeakMap();
 let dynamicDataViewReloadRevision = 0;
 
@@ -234,12 +235,20 @@ function escapeHtml(text: string): string {
     return text.replace(/[&<>"']/g, c => map[c]);
 }
 
-function registerDataViewPanel(panel: vscode.WebviewPanel, key: string, viewId: string, sessionId: string | null): void {
+function registerDataViewPanel(
+    panel: vscode.WebviewPanel, key: string, viewId: string, sessionId: string | null,
+    instance?: number,
+): void {
     // The panel's webview getter throws once onDidDispose fires.
     const webview = panel.webview;
     dynamicDataViewPanels.set(key, panel);
+    if (instance !== undefined) {
+        dynamicDataViewInstances.set(panel, instance);
+    }
     panel.onDidDispose(() => {
         listViewGenerations.delete(webview);
+        const currentInstance = dynamicDataViewInstances.get(panel);
+        dynamicDataViewInstances.delete(panel);
         if (dynamicDataViewPanels.get(key) !== panel) {
             return;
         }
@@ -248,7 +257,7 @@ function registerDataViewPanel(panel: vscode.WebviewPanel, key: string, viewId:
         if (sessions.get(sessionId ?? '')?.requester) { return; }
         void sessionRequest({
             method: 'dataview_dispose',
-            params: { view_id: viewId },
+            params: { view_id: viewId, instance: currentInstance },
         }, sessionId);
     });
 }
@@ -1022,6 +1031,7 @@ export async function showDataView(
     source: string, type: string, title: string, file: string, viewer: string,
     viewId?: string, navigation?: ListViewNavigation,
     sessionId: string | null = activeSession?.sessionId ?? null,
+    instance?: number,
 ): Promise {
     resDir ??= path.join(extensionContext.extensionPath, 'dist', 'resources');
     console.info(`[showDataView] source: ${source}, type: ${type}, title: ${title}, file: ${file}, viewer: ${viewer}, viewId: ${String(viewId ?? '')}`);
@@ -1031,6 +1041,9 @@ export async function showDataView(
         if (viewId) {
             const existing = dynamicDataViewPanels.get(panelKey);
             if (existing) {
+                if (instance !== undefined) {
+                    dynamicDataViewInstances.set(existing, instance);
+                }
                 existing.title = title;
                 existing.reveal(existing.viewColumn, true);
                 const content = await getTableHtml(existing.webview, undefined, title);
@@ -1052,7 +1065,7 @@ export async function showDataView(
             });
         panel.iconPath = new UriIcon('open-preview');
         if (viewId) {
-            registerDataViewPanel(panel, panelKey, viewId, sessionId);
+            registerDataViewPanel(panel, panelKey, viewId, sessionId, instance);
             attachDynamicDataViewBridge(panel, viewId, sessionId);
         }
         const content = await getTableHtml(panel.webview, file || undefined, title);
@@ -1061,6 +1074,9 @@ export async function showDataView(
         if (viewId) {
             const existing = dynamicDataViewPanels.get(panelKey);
             if (existing) {
+                if (instance !== undefined) {
+                    dynamicDataViewInstances.set(existing, instance);
+                }
                 existing.title = title;
                 existing.reveal(existing.viewColumn, true);
                 existing.webview.html = getListHtml(
@@ -1083,7 +1099,7 @@ export async function showDataView(
             });
         panel.iconPath = new UriIcon('preview');
         if (viewId) {
-            registerDataViewPanel(panel, panelKey, viewId, sessionId);
+            registerDataViewPanel(panel, panelKey, viewId, sessionId, instance);
             const webview = panel.webview;
             webview.onDidReceiveMessage(async (message: {
                 message?: string; index?: number; start?: number; requestId?: number;
@@ -2242,6 +2258,7 @@ async function handleNotification(message: Record, socket: IpcS
                         params.view_id ? String(params.view_id) : undefined,
                         params.navigation as ListViewNavigation | undefined,
                         socket._sessionId ?? null,
+                        typeof params.instance === 'number' ? params.instance : undefined,
                     );
                 }
             }
diff --git a/src/test/suite/dataViewerSessions.test.ts b/src/test/suite/dataViewerSessions.test.ts
index 3d7b576bb..457732dcc 100644
--- a/src/test/suite/dataViewerSessions.test.ts
+++ b/src/test/suite/dataViewerSessions.test.ts
@@ -11,7 +11,7 @@ import { mockExtensionContext } from '../common/mockvscode';
 interface Request {
     id: number;
     method: string;
-    params?: { view_id?: string };
+    params?: { view_id?: string; instance?: number };
 }
 
 interface Client {
@@ -137,11 +137,13 @@ suite('Viewer session ownership', () => {
         return client;
     }
 
-    async function open(client: Client, source: 'list' | 'table', existing?: Panel): Promise {
+    async function open(
+        client: Client, source: 'list' | 'table', existing?: Panel, instance = 1,
+    ): Promise {
         const count = panels.length;
         const html = existing?.panel.webview.html;
         notify(client, 'dataview', {
-            source, type: 'json', title: 'x', view_id: `same-${source}-id`,
+            source, type: 'json', title: 'x', view_id: `same-${source}-id`, instance,
             navigation: { title: 'x', path: [], breadcrumbs: [{ label: 'x', path: [] }] },
         });
         await waitFor(() => existing ? existing.panel.webview.html !== html : panels.length > count);
@@ -166,8 +168,8 @@ suite('Viewer session ownership', () => {
         const bList = await open(b, 'list');
         const bTable = await open(b, 'table');
         assert.strictEqual(panels.length, 4);
-        await open(a, 'list', aList);
-        await open(a, 'table', aTable);
+        await open(a, 'list', aList, 2);
+        await open(a, 'table', aTable, 2);
         assert.strictEqual(session.activeSession?.sessionId, b.id);
 
         const exercise = async (list: Panel, table: Panel) => {
@@ -185,11 +187,15 @@ suite('Viewer session ownership', () => {
         await exercise(bList, bTable);
         assert.deepStrictEqual(viewerRequests(b).map(request => request.method), expected);
 
+        await open(b, 'list', bList, 2);
+        await open(b, 'table', bTable, 2);
         bList.panel.dispose();
         bTable.panel.dispose();
         await waitFor(() => viewerRequests(b).length === 7);
         assert.deepStrictEqual(viewerRequests(b).slice(-2).map(request => request.params?.view_id),
             ['same-list-id', 'same-table-id']);
+        assert.deepStrictEqual(viewerRequests(b).slice(-2).map(request => request.params?.instance),
+            [2, 2]);
         assert.strictEqual(viewerRequests(a).length, 5);
         await open(a, 'list', aList);
         await open(a, 'table', aTable);

From 1d66df6d6bed9e45388d1f33e248357bbac22ea1 Mon Sep 17 00:00:00 2001
From: Fred-Wu <4111978+Fred-Wu@users.noreply.github.com>
Date: Sun, 4 Oct 2026 23:50:33 +1100
Subject: [PATCH 19/30] fix(viewer): isolate reloaded viewer responses

---
 sess/R/handlers.R                         |  8 +--
 sess/R/hooks.R                            |  4 +-
 sess/inst/tinytest/test-dataview.R        |  8 +--
 sess/inst/tinytest/test-listview.R        |  7 +-
 src/listViewer.ts                         | 10 +--
 src/session.ts                            | 85 +++++++++++++----------
 src/test/suite/dataViewerSessions.test.ts | 12 ++--
 src/test/suite/listViewerPanels.test.ts   | 58 +++++++++++++---
 8 files changed, 124 insertions(+), 68 deletions(-)

diff --git a/sess/R/handlers.R b/sess/R/handlers.R
index bf81338d3..e00907e62 100644
--- a/sess/R/handlers.R
+++ b/sess/R/handlers.R
@@ -808,7 +808,7 @@ dataview_set_state <- function(view_id, state) {
   if (is.null(.sess_env$dataviews)) {
     .sess_env$dataviews <- list()
   }
-  state$instance <- (.sess_env$dataviews[[view_id]]$instance %||% 0L) + 1L
+  state$state_generation <- (.sess_env$dataviews[[view_id]]$state_generation %||% 0L) + 1L
   .sess_env$dataviews[[view_id]] <- state
   state
 }
@@ -824,7 +824,7 @@ dataview_register <- function(data, view_id = NULL, live = FALSE) {
   state <- dataview_set_state(view_id, state)
   list(
     view_id = view_id,
-    instance = state$instance,
+    state_generation = state$state_generation,
     total_rows = state$total_rows,
     columns = dataview_columns(state)
   )
@@ -1276,8 +1276,8 @@ handle_dataview_page <- function(params) {
 handle_dataview_dispose <- function(params) {
   view_id <- as.character(params$view_id %||% "")
   state <- if (is.null(.sess_env$dataviews)) NULL else .sess_env$dataviews[[view_id]]
-  instance <- suppressWarnings(as.integer(params$instance %||% NA_integer_))
-  if (!is.null(state) && identical(state$instance, instance)) {
+  state_generation <- suppressWarnings(as.integer(params$state_generation %||% NA_integer_))
+  if (!is.null(state) && identical(state$state_generation, state_generation)) {
     .sess_env$dataviews[[view_id]] <- NULL
   }
   TRUE
diff --git a/sess/R/hooks.R b/sess/R/hooks.R
index 7a2081a3d..a76ae3d55 100644
--- a/sess/R/hooks.R
+++ b/sess/R/hooks.R
@@ -150,7 +150,7 @@ runtime_start <- function(use_rstudioapi = TRUE,
         source = "table",
         type = "json",
         view_id = registration$view_id,
-        instance = registration$instance
+        state_generation = registration$state_generation
       ))
     } else if (view_type == "list") {
       context <- .sess_env$listview_context
@@ -169,7 +169,7 @@ runtime_start <- function(use_rstudioapi = TRUE,
         source = view_type,
         type = "json",
         view_id = view_id,
-        instance = root$instance,
+        state_generation = root$state_generation,
         navigation = navigation
       ))
     } else {
diff --git a/sess/inst/tinytest/test-dataview.R b/sess/inst/tinytest/test-dataview.R
index b4d464b44..512998d20 100644
--- a/sess/inst/tinytest/test-dataview.R
+++ b/sess/inst/tinytest/test-dataview.R
@@ -393,20 +393,20 @@ local({
     replacement <- sess:::dataview_set_state(
       "replacement_test", cases[[name]]$replacement
     )
-    expect_true(replacement$instance > first$instance, info = name)
+    expect_true(replacement$state_generation > first$state_generation, info = name)
 
     expect_true(sess:::handle_dataview_dispose(list(
-      view_id = "replacement_test", instance = first$instance
+      view_id = "replacement_test", state_generation = first$state_generation
     )), info = name)
     expect_identical(
-      runtime$dataviews$replacement_test$instance, replacement$instance, info = name
+      runtime$dataviews$replacement_test$state_generation, replacement$state_generation, info = name
     )
     expect_identical(
       runtime$dataviews$replacement_test$data, cases[[name]]$replacement$data, info = name
     )
 
     expect_true(sess:::handle_dataview_dispose(list(
-      view_id = "replacement_test", instance = replacement$instance
+      view_id = "replacement_test", state_generation = replacement$state_generation
     )), info = name)
     expect_null(runtime$dataviews$replacement_test, info = name)
   }
diff --git a/sess/inst/tinytest/test-listview.R b/sess/inst/tinytest/test-listview.R
index 3ae56614d..252a46a17 100644
--- a/sess/inst/tinytest/test-listview.R
+++ b/sess/inst/tinytest/test-listview.R
@@ -13,7 +13,10 @@ local({
     runtime$con <- previous_con
     runtime$dataviews <- previous_views
     runtime$dataview_registry <- previous_registry
-    rm(list = c(root, other, table_root), envir = .GlobalEnv)
+    rm(
+      list = intersect(c(root, other, table_root), ls(envir = .GlobalEnv, all.names = TRUE)),
+      envir = .GlobalEnv
+    )
     lapply(pipe, close)
   }, add = TRUE)
   runtime$con <- pipe[[2L]]
@@ -479,7 +482,7 @@ local({
   expect_false(sess:::handle_listview_view(list_id, 1.5))
   expect_false(sess:::handle_listview_view(list_id, 1L, list(99L)))
   expect_true(sess:::handle_dataview_dispose(list(
-    view_id = list_id, instance = runtime$dataviews[[list_id]]$instance
+    view_id = list_id, state_generation = runtime$dataviews[[list_id]]$state_generation
   )))
   expect_null(runtime$dataviews[[list_id]])
   sess:::handle_workspace_view(root)
diff --git a/src/listViewer.ts b/src/listViewer.ts
index 34d8526d2..f680ebe9a 100644
--- a/src/listViewer.ts
+++ b/src/listViewer.ts
@@ -7,12 +7,12 @@ export interface ListViewNavigation {
 }
 
 /** Script shared by the list webview and its interaction tests. */
-export function getListViewerScript(generation: number, initial: ListViewNavigation = {
+export function getListViewerScript(documentGeneration: number, initial: ListViewNavigation = {
     title: '', path: [], breadcrumbs: [{ label: '', path: [] }],
 }): string {
     return `
     const vscode = acquireVsCodeApi();
-    const generation = ${generation};
+    const documentGeneration = ${documentGeneration};
     const pending = new Map();
     let nextRequestId = 0;
     const list = document.getElementById('list');
@@ -75,7 +75,7 @@ export function getListViewerScript(generation: number, initial: ListViewNavigat
                 showNavigation(response.navigation, goingBack);
             }
         });
-        vscode.postMessage({ message, generation, requestId, ...params });
+        vscode.postMessage({ message, documentGeneration, requestId, ...params });
     }
 
     back.addEventListener('click', () => {
@@ -164,7 +164,7 @@ export function getListViewerScript(generation: number, initial: ListViewNavigat
                 more.textContent = 'Load more';
                 status.textContent = rows.childElementCount ? '' : 'No items';
             });
-            vscode.postMessage({ message: 'listview/page', generation, requestId, path, start: nextStart });
+            vscode.postMessage({ message: 'listview/page', documentGeneration, requestId, path, start: nextStart });
         }
         more.addEventListener('click', loadPage);
         return { loadOnce: () => { if (!loaded) loadPage(); } };
@@ -172,7 +172,7 @@ export function getListViewerScript(generation: number, initial: ListViewNavigat
 
     window.addEventListener('message', (event) => {
         const message = event.data;
-        if (!['listview/page', 'listview/navigation'].includes(message.message) || message.generation !== generation) return;
+        if (!['listview/page', 'listview/navigation'].includes(message.message) || message.documentGeneration !== documentGeneration) return;
         const receive = pending.get(message.requestId);
         if (receive) {
             pending.delete(message.requestId);
diff --git a/src/session.ts b/src/session.ts
index c7f338544..160410b15 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -213,6 +213,7 @@ interface DataViewRequestMessage {
     message: 'dataview/request';
     action: 'init' | 'page';
     requestId: number;
+    documentGeneration: number;
     startRow?: number;
     endRow?: number;
     sortModel?: unknown[];
@@ -220,9 +221,9 @@ interface DataViewRequestMessage {
 }
 
 const dynamicDataViewPanels = new Map();
-const dynamicDataViewInstances = new WeakMap();
-const listViewGenerations = new WeakMap();
-let dynamicDataViewReloadRevision = 0;
+const dynamicDataViewStateGenerations = new WeakMap();
+const documentGenerations = new WeakMap();
+let documentGenerationRevision = 0;
 
 function escapeHtml(text: string): string {
     const map: Record = {
@@ -237,18 +238,18 @@ function escapeHtml(text: string): string {
 
 function registerDataViewPanel(
     panel: vscode.WebviewPanel, key: string, viewId: string, sessionId: string | null,
-    instance?: number,
+    stateGeneration?: number,
 ): void {
     // The panel's webview getter throws once onDidDispose fires.
     const webview = panel.webview;
     dynamicDataViewPanels.set(key, panel);
-    if (instance !== undefined) {
-        dynamicDataViewInstances.set(panel, instance);
+    if (stateGeneration !== undefined) {
+        dynamicDataViewStateGenerations.set(panel, stateGeneration);
     }
     panel.onDidDispose(() => {
-        listViewGenerations.delete(webview);
-        const currentInstance = dynamicDataViewInstances.get(panel);
-        dynamicDataViewInstances.delete(panel);
+        documentGenerations.delete(webview);
+        const currentStateGeneration = dynamicDataViewStateGenerations.get(panel);
+        dynamicDataViewStateGenerations.delete(panel);
         if (dynamicDataViewPanels.get(key) !== panel) {
             return;
         }
@@ -257,16 +258,22 @@ function registerDataViewPanel(
         if (sessions.get(sessionId ?? '')?.requester) { return; }
         void sessionRequest({
             method: 'dataview_dispose',
-            params: { view_id: viewId, instance: currentInstance },
+            params: { view_id: viewId, state_generation: currentStateGeneration },
         }, sessionId);
     });
 }
 
 function attachDynamicDataViewBridge(panel: vscode.WebviewPanel, viewId: string, sessionId: string | null): void {
     const webview = panel.webview;
-    const postResponse = (requestId: number, ok: boolean, result?: unknown, error?: string) => {
+    const postResponse = (
+        documentGeneration: number, requestId: number, ok: boolean, result?: unknown, error?: string
+    ) => {
+        if (documentGeneration !== documentGenerations.get(webview)) {
+            return;
+        }
         void webview.postMessage({
             message: 'dataview/response',
+            documentGeneration,
             requestId,
             ok,
             result,
@@ -276,7 +283,9 @@ function attachDynamicDataViewBridge(panel: vscode.WebviewPanel, viewId: string,
 
     webview.onDidReceiveMessage(async (raw: unknown) => {
         const msg = raw as Partial;
-        if (msg.message !== 'dataview/request' || typeof msg.requestId !== 'number') {
+        if (msg.message !== 'dataview/request' || typeof msg.requestId !== 'number' ||
+            typeof msg.documentGeneration !== 'number' ||
+            msg.documentGeneration !== documentGenerations.get(webview)) {
             return;
         }
 
@@ -289,7 +298,7 @@ function attachDynamicDataViewBridge(panel: vscode.WebviewPanel, viewId: string,
                 if (!result || !Array.isArray(result.columns) || typeof result.totalRows !== 'number') {
                     throw new Error('Invalid dataview_init response');
                 }
-                postResponse(msg.requestId, true, result);
+                postResponse(msg.documentGeneration, msg.requestId, true, result);
                 return;
             }
 
@@ -309,13 +318,13 @@ function attachDynamicDataViewBridge(panel: vscode.WebviewPanel, viewId: string,
                     typeof result.totalUnfiltered !== 'number') {
                     throw new Error('Invalid dataview_page response');
                 }
-                postResponse(msg.requestId, true, result);
+                postResponse(msg.documentGeneration, msg.requestId, true, result);
                 return;
             }
 
-            postResponse(msg.requestId, false, undefined, `Unsupported dataview action: ${String(msg.action)}`);
+            postResponse(msg.documentGeneration, msg.requestId, false, undefined, `Unsupported dataview action: ${String(msg.action)}`);
         } catch (e) {
-            postResponse(msg.requestId, false, undefined, e instanceof Error ? e.message : String(e));
+            postResponse(msg.documentGeneration, msg.requestId, false, undefined, e instanceof Error ? e.message : String(e));
         }
     });
 }
@@ -1031,7 +1040,7 @@ export async function showDataView(
     source: string, type: string, title: string, file: string, viewer: string,
     viewId?: string, navigation?: ListViewNavigation,
     sessionId: string | null = activeSession?.sessionId ?? null,
-    instance?: number,
+    stateGeneration?: number,
 ): Promise {
     resDir ??= path.join(extensionContext.extensionPath, 'dist', 'resources');
     console.info(`[showDataView] source: ${source}, type: ${type}, title: ${title}, file: ${file}, viewer: ${viewer}, viewId: ${String(viewId ?? '')}`);
@@ -1041,13 +1050,12 @@ export async function showDataView(
         if (viewId) {
             const existing = dynamicDataViewPanels.get(panelKey);
             if (existing) {
-                if (instance !== undefined) {
-                    dynamicDataViewInstances.set(existing, instance);
+                if (stateGeneration !== undefined) {
+                    dynamicDataViewStateGenerations.set(existing, stateGeneration);
                 }
                 existing.title = title;
                 existing.reveal(existing.viewColumn, true);
-                const content = await getTableHtml(existing.webview, undefined, title);
-                existing.webview.html = `${content}\n`;
+                existing.webview.html = await getTableHtml(existing.webview, undefined, title);
                 return;
             }
         }
@@ -1065,7 +1073,7 @@ export async function showDataView(
             });
         panel.iconPath = new UriIcon('open-preview');
         if (viewId) {
-            registerDataViewPanel(panel, panelKey, viewId, sessionId, instance);
+            registerDataViewPanel(panel, panelKey, viewId, sessionId, stateGeneration);
             attachDynamicDataViewBridge(panel, viewId, sessionId);
         }
         const content = await getTableHtml(panel.webview, file || undefined, title);
@@ -1074,8 +1082,8 @@ export async function showDataView(
         if (viewId) {
             const existing = dynamicDataViewPanels.get(panelKey);
             if (existing) {
-                if (instance !== undefined) {
-                    dynamicDataViewInstances.set(existing, instance);
+                if (stateGeneration !== undefined) {
+                    dynamicDataViewStateGenerations.set(existing, stateGeneration);
                 }
                 existing.title = title;
                 existing.reveal(existing.viewColumn, true);
@@ -1099,13 +1107,13 @@ export async function showDataView(
             });
         panel.iconPath = new UriIcon('preview');
         if (viewId) {
-            registerDataViewPanel(panel, panelKey, viewId, sessionId, instance);
+            registerDataViewPanel(panel, panelKey, viewId, sessionId, stateGeneration);
             const webview = panel.webview;
             webview.onDidReceiveMessage(async (message: {
                 message?: string; index?: number; start?: number; requestId?: number;
-                path?: number[]; generation?: number;
+                path?: number[]; documentGeneration?: number;
             }) => {
-                if (message.generation !== listViewGenerations.get(webview)) {
+                if (message.documentGeneration !== documentGenerations.get(webview)) {
                     return;
                 }
                 if (!Array.isArray(message.path) || !message.path.every(index => Number.isSafeInteger(index) && index > 0)) {
@@ -1117,7 +1125,7 @@ export async function showDataView(
                         method: message.message === 'listview/navigate' ? 'listview_navigate' : 'listview_view',
                         params: { view_id: viewId, index: message.index, path: message.path },
                     }, sessionId) as ListViewNavigation | boolean | undefined;
-                    if (message.generation !== listViewGenerations.get(webview)) {
+                    if (message.documentGeneration !== documentGenerations.get(webview)) {
                         return;
                     }
                     const navigation = result && typeof result === 'object' && Array.isArray(result.breadcrumbs)
@@ -1127,7 +1135,7 @@ export async function showDataView(
                     }
                     void webview.postMessage({
                         message: 'listview/navigation',
-                        generation: message.generation,
+                        documentGeneration: message.documentGeneration,
                         requestId: message.requestId,
                         navigation,
                         error: result ? undefined : 'Unable to open this item. Check the R session and try again.',
@@ -1138,12 +1146,12 @@ export async function showDataView(
                         method: 'workspace_children',
                         params: { view_id: viewId, start: message.start, path: message.path },
                     }, sessionId) as { children?: unknown; next_start?: number | null } | undefined;
-                    if (message.generation !== listViewGenerations.get(webview)) {
+                    if (message.documentGeneration !== documentGenerations.get(webview)) {
                         return;
                     }
                     void webview.postMessage({
                         message: 'listview/page',
-                        generation: message.generation,
+                        documentGeneration: message.documentGeneration,
                         requestId: message.requestId,
                         ...page,
                         error: Array.isArray(page?.children) ? undefined : 'Unable to load items. Check the R session and try again.',
@@ -1167,6 +1175,8 @@ export async function showDataView(
 export async function getTableHtml(webview: Webview, file: string | undefined, title: string): Promise {
     const pageSize = config().get('session.data.pageSize', 500);
     if (!file) {
+        const documentGeneration = ++documentGenerationRevision;
+        documentGenerations.set(webview, documentGeneration);
         return `
 
 
@@ -1344,6 +1354,7 @@ export async function getTableHtml(webview: Webview, file: string | undefined, t
     
     
@@ -2258,7 +2271,7 @@ async function handleNotification(message: Record, socket: IpcS
                         params.view_id ? String(params.view_id) : undefined,
                         params.navigation as ListViewNavigation | undefined,
                         socket._sessionId ?? null,
-                        typeof params.instance === 'number' ? params.instance : undefined,
+                        typeof params.state_generation === 'number' ? params.state_generation : undefined,
                     );
                 }
             }
diff --git a/src/test/suite/dataViewerSessions.test.ts b/src/test/suite/dataViewerSessions.test.ts
index 457732dcc..42e2bbeac 100644
--- a/src/test/suite/dataViewerSessions.test.ts
+++ b/src/test/suite/dataViewerSessions.test.ts
@@ -11,7 +11,7 @@ import { mockExtensionContext } from '../common/mockvscode';
 interface Request {
     id: number;
     method: string;
-    params?: { view_id?: string; instance?: number };
+    params?: { view_id?: string; state_generation?: number };
 }
 
 interface Client {
@@ -138,12 +138,12 @@ suite('Viewer session ownership', () => {
     }
 
     async function open(
-        client: Client, source: 'list' | 'table', existing?: Panel, instance = 1,
+        client: Client, source: 'list' | 'table', existing?: Panel, stateGeneration = 1,
     ): Promise {
         const count = panels.length;
         const html = existing?.panel.webview.html;
         notify(client, 'dataview', {
-            source, type: 'json', title: 'x', view_id: `same-${source}-id`, instance,
+            source, type: 'json', title: 'x', view_id: `same-${source}-id`, state_generation: stateGeneration,
             navigation: { title: 'x', path: [], breadcrumbs: [{ label: 'x', path: [] }] },
         });
         await waitFor(() => existing ? existing.panel.webview.html !== html : panels.length > count);
@@ -154,8 +154,8 @@ suite('Viewer session ownership', () => {
     }
 
     async function send(panel: Panel, message: Record): Promise {
-        const generation = Number(/const generation = (\d+)/.exec(panel.panel.webview.html)?.[1]);
-        await panel.receive({ generation, requestId: 1, path: [], start: 1, ...message });
+        const documentGeneration = Number(/const documentGeneration = (\d+)/.exec(panel.panel.webview.html)?.[1]);
+        await panel.receive({ documentGeneration, requestId: 1, path: [], start: 1, ...message });
     }
 
     const viewerRequests = (client: Client) => client.requests.filter(request => request.method !== 'workspace');
@@ -194,7 +194,7 @@ suite('Viewer session ownership', () => {
         await waitFor(() => viewerRequests(b).length === 7);
         assert.deepStrictEqual(viewerRequests(b).slice(-2).map(request => request.params?.view_id),
             ['same-list-id', 'same-table-id']);
-        assert.deepStrictEqual(viewerRequests(b).slice(-2).map(request => request.params?.instance),
+        assert.deepStrictEqual(viewerRequests(b).slice(-2).map(request => request.params?.state_generation),
             [2, 2]);
         assert.strictEqual(viewerRequests(a).length, 5);
         await open(a, 'list', aList);
diff --git a/src/test/suite/listViewerPanels.test.ts b/src/test/suite/listViewerPanels.test.ts
index ad757b28d..4aeafd8a2 100644
--- a/src/test/suite/listViewerPanels.test.ts
+++ b/src/test/suite/listViewerPanels.test.ts
@@ -56,13 +56,13 @@ suite('List viewer panels', () => {
             const receive = sandbox.spy(panel.webview, 'onDidReceiveMessage');
             sandbox.stub(vscode.window, 'createWebviewPanel').returns(panel);
             await session.showDataView(source, 'json', 'x', '', 'Two', `test-pending-${source}`);
-            const generation = Number(/const generation = (\d+)/.exec(panel.webview.html)?.[1]);
+            const documentGeneration = Number(/const documentGeneration = (\d+)/.exec(panel.webview.html)?.[1]);
             const listener = receive.firstCall.args[0] as (message: unknown) => Promise;
             // With no R session, requests settle asynchronously with an unavailable response.
             const pending = source === 'table'
                 ? [listener({ message: 'dataview/request', action: 'page', requestId: 1 })]
                 : ['listview/page', 'listview/navigate'].map(message => listener({
-                    message, generation, requestId: 1, path: [], start: 1,
+                    message, documentGeneration, requestId: 1, path: [], start: 1,
                 }));
             panel.dispose();
             await Promise.all(pending);
@@ -140,24 +140,64 @@ suite('List viewer panels', () => {
         } as unknown as vscode.WebviewPanel;
         panels.push(panel);
         sandbox.stub(vscode.window, 'createWebviewPanel').returns(panel);
-        const generation = () => Number(/const generation = (\d+)/.exec(panel.webview.html)?.[1]);
-        await session.showDataView('list', 'json', 'x', '', 'Two', 'test-list-generation');
+        const documentGeneration = () => Number(/const documentGeneration = (\d+)/.exec(panel.webview.html)?.[1]);
+        await session.showDataView('list', 'json', 'x', '', 'Two', 'test-list-document-generation');
 
         for (const message of ['listview/navigate', 'listview/page']) {
-            const request = { message, generation: generation(), requestId: 1, path: [], start: 1 };
+            const request = { message, documentGeneration: documentGeneration(), requestId: 1, path: [], start: 1 };
             // sessionRequest settles asynchronously even without an attached R session.
             const pending = receive(request);
-            await session.showDataView('list', 'json', 'x$updated', '', 'Two', 'test-list-generation');
+            await session.showDataView('list', 'json', 'x$updated', '', 'Two', 'test-list-document-generation');
             await pending;
             sinon.assert.notCalled(postMessage);
             await receive(request);
             sinon.assert.notCalled(postMessage);
             assert.strictEqual(panel.title, 'x$updated');
         }
-        await receive({ message: 'listview/page', generation: generation(), requestId: 2, path: [], start: 1 });
+        await receive({ message: 'listview/page', documentGeneration: documentGeneration(), requestId: 2, path: [], start: 1 });
         sinon.assert.calledOnce(postMessage);
-        const response = postMessage.firstCall.args[0] as { generation: number };
-        assert.strictEqual(response.generation, generation());
+        const response = postMessage.firstCall.args[0] as { documentGeneration: number };
+        assert.strictEqual(response.documentGeneration, documentGeneration());
+    });
+
+    test('ignores requests and replies from a previous data viewer document after panel reuse', async () => {
+        let receive: (message: unknown) => Promise = () => Promise.resolve();
+        const postMessage = sandbox.stub().resolves(true);
+        const disposed = new vscode.EventEmitter();
+        const panel = {
+            title: '', viewColumn: vscode.ViewColumn.Two, reveal: sandbox.stub(),
+            webview: {
+                html: '', asWebviewUri: (uri: vscode.Uri) => uri, postMessage,
+                onDidReceiveMessage: (listener: typeof receive) => { receive = listener; },
+            },
+            onDidDispose: disposed.event,
+            dispose: () => { disposed.fire(); disposed.dispose(); },
+        } as unknown as vscode.WebviewPanel;
+        panels.push(panel);
+        sandbox.stub(vscode.window, 'createWebviewPanel').returns(panel);
+        const documentGeneration = () =>
+            Number(/const documentGeneration = (\d+)/.exec(panel.webview.html)?.[1]);
+        await session.showDataView('table', 'json', 'x', '', 'Two', 'test-dataview-document-generation');
+
+        const request = {
+            message: 'dataview/request', action: 'page',
+            documentGeneration: documentGeneration(), requestId: 1,
+        };
+        const pending = receive(request);
+        await session.showDataView(
+            'table', 'json', 'x$updated', '', 'Two', 'test-dataview-document-generation'
+        );
+        await pending;
+        sinon.assert.notCalled(postMessage);
+        await receive(request);
+        sinon.assert.notCalled(postMessage);
+
+        await receive({
+            ...request, documentGeneration: documentGeneration(), requestId: 2,
+        });
+        sinon.assert.calledOnce(postMessage);
+        const response = postMessage.firstCall.args[0] as { documentGeneration: number };
+        assert.strictEqual(response.documentGeneration, documentGeneration());
     });
 
     test('supported workspace children retain open actions alongside expansion', () => {

From 13997ce2e5a2e852c0b0eaef44b6a4dabcf99300 Mon Sep 17 00:00:00 2001
From: Fred-Wu <4111978+Fred-Wu@users.noreply.github.com>
Date: Mon, 5 Oct 2026 00:15:30 +1100
Subject: [PATCH 20/30] fix(viewer): update runtime start test arguments

---
 sess/inst/tinytest/test-listview.R | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sess/inst/tinytest/test-listview.R b/sess/inst/tinytest/test-listview.R
index 252a46a17..abb071211 100644
--- a/sess/inst/tinytest/test-listview.R
+++ b/sess/inst/tinytest/test-listview.R
@@ -20,7 +20,7 @@ local({
     lapply(pipe, close)
   }, add = TRUE)
   runtime$con <- pipe[[2L]]
-  sess:::runtime_start(use_rstudioapi = FALSE, use_httpgd = FALSE, use_jgd = FALSE)
+  sess:::runtime_start(use_rstudioapi = FALSE, plot_backend = "standard")
   x <- list(a = list(b = list(value = 1L), df = data.frame(nested = 2L)),
             df = data.frame(top = 1L))
   assign(root, x, envir = .GlobalEnv)

From 906376552490e4e92d55706d5d72d2a6a0cdc14e Mon Sep 17 00:00:00 2001
From: Fred-Wu <4111978+Fred-Wu@users.noreply.github.com>
Date: Mon, 5 Oct 2026 00:19:03 +1100
Subject: [PATCH 21/30] fix(viewer): update viewer lifecycle test

---
 sess/inst/tinytest/test-ipc.R | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sess/inst/tinytest/test-ipc.R b/sess/inst/tinytest/test-ipc.R
index 8ed00b95d..372e34f0a 100644
--- a/sess/inst/tinytest/test-ipc.R
+++ b/sess/inst/tinytest/test-ipc.R
@@ -158,7 +158,10 @@ local({
   response <- jsonlite::fromJSON(processx::conn_read_chars(pipe[[1L]]))
   expect_true(all(abs(response$result$rows[["1"]] - expected) <= abs(expected) * 1e-14))
 
-  disposed <- sess:::handle_dataview_dispose(list(view_id = registration$view_id))
+  disposed <- sess:::handle_dataview_dispose(list(
+    view_id = registration$view_id,
+    state_generation = registration$state_generation
+  ))
   expect_true(isTRUE(disposed))
   expect_error(
     sess:::handle_dataview_init(list(view_id = registration$view_id)),

From 2afc534a69db372e24069762bfdf743b8b2f7907 Mon Sep 17 00:00:00 2001
From: Fred-Wu <4111978+Fred-Wu@users.noreply.github.com>
Date: Mon, 5 Oct 2026 00:24:02 +1100
Subject: [PATCH 22/30] fix(viewer): update document generation test

---
 src/test/suite/listViewer.test.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/test/suite/listViewer.test.ts b/src/test/suite/listViewer.test.ts
index d0e9e6ace..5ec49ffa0 100644
--- a/src/test/suite/listViewer.test.ts
+++ b/src/test/suite/listViewer.test.ts
@@ -26,7 +26,7 @@ class Element {
 
 interface Request {
     message: string;
-    generation: number;
+    documentGeneration: number;
     requestId: number;
     path: number[];
     index?: number;
@@ -280,7 +280,7 @@ suite('List viewer', () => {
 
     test('ignores old viewer responses and hides open buttons for unavailable items', () => {
         const { root, messages, reply } = createViewer();
-        reply(messages[0], { generation: 6, children: [{ label: 'stale' }] });
+        reply(messages[0], { documentGeneration: 6, children: [{ label: 'stale' }] });
         assert.strictEqual(root.children[0].childElementCount, 0);
         reply(messages[0], { children: [
             { label: 'removed', viewable: false },

From 15066ab90522b535c25827a227c78cd718abdb03 Mon Sep 17 00:00:00 2001
From: Fred-Wu <4111978+Fred-Wu@users.noreply.github.com>
Date: Mon, 5 Oct 2026 01:01:41 +1100
Subject: [PATCH 23/30] fix(viewer): cover pending data viewer request

---
 src/test/suite/listViewerPanels.test.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/test/suite/listViewerPanels.test.ts b/src/test/suite/listViewerPanels.test.ts
index 4aeafd8a2..0b84e18ec 100644
--- a/src/test/suite/listViewerPanels.test.ts
+++ b/src/test/suite/listViewerPanels.test.ts
@@ -60,7 +60,9 @@ suite('List viewer panels', () => {
             const listener = receive.firstCall.args[0] as (message: unknown) => Promise;
             // With no R session, requests settle asynchronously with an unavailable response.
             const pending = source === 'table'
-                ? [listener({ message: 'dataview/request', action: 'page', requestId: 1 })]
+                ? [listener({
+                    message: 'dataview/request', action: 'page', documentGeneration, requestId: 1,
+                })]
                 : ['listview/page', 'listview/navigate'].map(message => listener({
                     message, documentGeneration, requestId: 1, path: [], start: 1,
                 }));

From b2d72f819b3b2ffac14b2df30195b607cd6bffde Mon Sep 17 00:00:00 2001
From: "4111978+Fred-Wu@users.noreply.github.com"
 <4111978+Fred-Wu@users.noreply.github.com>
Date: Mon, 5 Oct 2026 01:51:18 +1100
Subject: [PATCH 24/30] Bumped sess IPC to version 2

---
 sess/R/handlers.R                             |  2 +-
 sess/R/hooks.R                                |  3 +-
 sess/R/server.R                               |  2 +-
 sess/README.md                                | 19 +++++++++++--
 .../tinytest/test-interactive-large-table.R   |  3 ++
 sess/inst/tinytest/test-session-contract.R    |  2 +-
 src/interactive/backends/sessBridge.ts        |  2 +-
 src/interactive/manager.ts                    | 13 +++++++++
 src/session.ts                                |  4 +--
 src/test/suite/dataViewerSessions.test.ts     | 24 +++++++++++++++-
 src/test/suite/interactiveEditor.test.ts      | 28 +++++++++++++++++++
 src/test/suite/session.test.ts                | 20 ++++++-------
 src/test/suite/workspaceViewer.test.ts        | 19 +++++++++++++
 src/workspaceViewer.ts                        |  4 +++
 14 files changed, 124 insertions(+), 21 deletions(-)

diff --git a/sess/R/handlers.R b/sess/R/handlers.R
index e00907e62..bc96216ed 100644
--- a/sess/R/handlers.R
+++ b/sess/R/handlers.R
@@ -845,7 +845,7 @@ dataview_get_state <- function(view_id, refresh = FALSE) {
           !identical(state$total_rows, current$total_rows)) {
       current$live <- TRUE
       current$revision <- revision
-      current$instance <- state$instance
+      current$state_generation <- state$state_generation
       state <- current
       .sess_env$dataviews[[view_id]] <- state
     }
diff --git a/sess/R/hooks.R b/sess/R/hooks.R
index a76ae3d55..549c59ab6 100644
--- a/sess/R/hooks.R
+++ b/sess/R/hooks.R
@@ -116,7 +116,8 @@ runtime_start <- function(use_rstudioapi = TRUE,
     }
     force(title)
 
-    if (isTRUE(.sess_env$interactive_connected) && .interactive_rich_value(x)) {
+    if (is.null(.sess_env$view_owner) && isTRUE(.sess_env$interactive_connected) &&
+          .interactive_rich_value(x)) {
       return(invisible(NULL))
     }
 
diff --git a/sess/R/server.R b/sess/R/server.R
index 6fb92ca9d..1882ad2f0 100644
--- a/sess/R/server.R
+++ b/sess/R/server.R
@@ -256,7 +256,7 @@ connect <- function(endpoint = NULL, use_rstudioapi = TRUE, use_httpgd = NULL,
   host <- Sys.info()[["nodename"]]
   if (is.null(host) || is.na(host)) host <- ""
   list(
-    protocol_version = 1L,
+    protocol_version = 2L,
     interactive_token = .sess_env$interactive_token,
     sess_version = as.character(utils::packageVersion("sess")),
     session_id = .session_id(),
diff --git a/sess/README.md b/sess/README.md
index f2b948687..c999fe1ad 100644
--- a/sess/README.md
+++ b/sess/README.md
@@ -193,7 +193,7 @@ On connecting, `sess` sends an `attach` notification:
   "jsonrpc": "2.0",
   "method": "attach",
   "params": {
-    "protocol_version": 1,
+    "protocol_version": 2,
     "sess_version": "3.0.0",
     "session_id": "sess-session-...",
     "host": "compute42",
@@ -217,6 +217,12 @@ The attached socket's lifetime controls cleanup. A replacement socket with the
 same identity supersedes the old one; a late close cannot remove its replacement.
 A fork child receives its own identity. Terminal PID association is local-only.
 
+Protocol version 2 includes the viewer-state generation contract: dynamic table
+and list `dataview` notifications provide `state_generation`, and
+`dataview_dispose` requires it. Both the extension and `sess` must support version
+2. The extension/webview `documentGeneration` field is internal to the client
+and is not part of the `sess` IPC contract.
+
 ### Notifications from R to client
 
 Sent with `notify_client()`.
@@ -225,7 +231,7 @@ Sent with `notify_client()`.
 |---|---|---|
 | `attach` | see above | Connection is established. |
 | `workspace_updated` | none | A top-level command completes. |
-| `dataview` | `title`, `source`, `type`, and `view_id` (tables) or `file` (other objects) | `View()` is called. |
+| `dataview` | `title`, `source`, `type`; `view_id` and `state_generation` for tables/lists, plus `navigation` for lists; `file` for other objects | `View()` is called. |
 | `plot_updated` | none | The standard device records a new or changed plot. |
 | `httpgd` | `url` | An httpgd device is opened. |
 | `help` | `requestPath` | A help page or help search is printed. |
@@ -258,7 +264,14 @@ arrives. All are used by `rstudioapi` emulation:
 | `plot_latest` | `width`, `height`, `format` (`svglite` or `png`), `devArgs` | `format`, `data` (base64) |
 | `dataview_init` | `view_id` | `columns`, `totalRows` |
 | `dataview_page` | `view_id`, `startRow`, `endRow`, `sortModel`, `filterModel` | `rows`, `totalRows`, `totalUnfiltered`, `lastRow` |
-| `dataview_dispose` | `view_id` | `true` |
+| `dataview_dispose` | `view_id`, `state_generation` | `true` |
+
+`state_generation` is an integer issued by `sess` when viewer data is registered.
+It changes when data for an existing `view_id` is replaced. When closing a viewer,
+the client sends the `state_generation` from its latest `dataview` notification.
+Disposal deletes data only if the generation matches the current registration;
+a missing or mismatched generation leaves the data intact and still returns
+`true`. This prevents a delayed close request from deleting replacement data.
 
 Example exchange:
 
diff --git a/sess/inst/tinytest/test-interactive-large-table.R b/sess/inst/tinytest/test-interactive-large-table.R
index 8e1e9ff09..45799fead 100644
--- a/sess/inst/tinytest/test-interactive-large-table.R
+++ b/sess/inst/tinytest/test-interactive-large-table.R
@@ -22,6 +22,9 @@ local({
   expect_identical(small$value$x1, 1:1000)
   expect_true(as.numeric(object.size(small$value)) < 200000)
   full <- register(large, live = TRUE)$view_id
+  generation <- env$dataviews[[full]]$state_generation
+  sess:::handle_dataview_init(list(view_id = full))
+  expect_identical(env$dataviews[[full]]$state_generation, generation)
   expect_identical(page(full, startRow = n - 2L, endRow = n)$rows[["1"]], (n - 1L):n)
   expect_null(env$dataviews[[full]]$query_indices)
 
diff --git a/sess/inst/tinytest/test-session-contract.R b/sess/inst/tinytest/test-session-contract.R
index d19ecee83..3518957fc 100644
--- a/sess/inst/tinytest/test-session-contract.R
+++ b/sess/inst/tinytest/test-session-contract.R
@@ -13,7 +13,7 @@ local({
   first <- sess:::.session_attach_metadata()
   second <- sess:::.session_attach_metadata()
 
-  expect_equal(first$protocol_version, 1L)
+  expect_equal(first$protocol_version, 2L)
   expect_true(is.character(first$session_id) && nzchar(first$session_id))
   expect_equal(first$session_id, second$session_id)
   expect_false(identical(first$session_id, as.character(first$pid)))
diff --git a/src/interactive/backends/sessBridge.ts b/src/interactive/backends/sessBridge.ts
index 3d1e7baae..d19e50cdf 100644
--- a/src/interactive/backends/sessBridge.ts
+++ b/src/interactive/backends/sessBridge.ts
@@ -55,7 +55,7 @@ export class SessBridge {
         this.parse(socket, message => {
             if (message.method === 'attach') {
                 const params = object(message.params);
-                if (params.protocol_version !== 1 || params.interactive_token !== this.token ||
+                if (params.protocol_version !== 2 || params.interactive_token !== this.token ||
                     (this.sess && this.sess !== socket)) { socket.destroy(); return; }
                 this.sess = socket; attached = true;
                 this.emit({ type: 'metadata', metadata: { rPid: Number(params.pid), rVersion: String(params.version),
diff --git a/src/interactive/manager.ts b/src/interactive/manager.ts
index 57c0c4098..692753deb 100644
--- a/src/interactive/manager.ts
+++ b/src/interactive/manager.ts
@@ -16,6 +16,7 @@ import { DISPLAY_MIME, InteractiveSerializer } from './notebook';
 import { setInteractiveExecutor } from './executionTarget';
 import * as session from '../session';
 import * as util from '../util';
+import type { ListViewNavigation } from '../listViewer';
 import { escapeXml } from './plotSvg';
 import { ensureWorkspaceViewer } from '../extension';
 import { queryTablePage } from './tableQuery';
@@ -951,6 +952,18 @@ export class InteractiveManager implements vscode.Disposable, vscode.TreeDataPro
             void this.prompt(view, event.data);
         } else if (event.type === 'clientRequest' && view.client.control) {
             void this.clientRequest(view, event.data);
+        } else if (event.type === 'viewer' && event.data.method === 'dataview') {
+            const params = object(event.data.params ?? {});
+            const viewer = util.config().get>('session.viewers.viewColumn')?.view ?? 'Two';
+            if (viewer !== 'Disable' && params.source && params.type && params.title) {
+                await session.showDataView(
+                    String(params.source), String(params.type), String(params.title), String(params.file ?? ''), viewer,
+                    params.view_id ? String(params.view_id) : undefined,
+                    params.navigation as ListViewNavigation | undefined,
+                    view.target.sessionId,
+                    typeof params.state_generation === 'number' ? params.state_generation : undefined,
+                );
+            }
         } else if (event.type === 'notification') {
             const params = object(event.data.params ?? {});
             if (event.data.method === 'help') { await session.showHelpNotification(params); }
diff --git a/src/session.ts b/src/session.ts
index 160410b15..2e5553f48 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -100,7 +100,7 @@ let info: SessionInfo;
 export let globalPipePath: string | undefined;
 export let workspaceFile: string;
 
-const SESS_PROTOCOL_VERSION = 1;
+const SESS_PROTOCOL_VERSION = 2;
 
 const sessions = new Map();
 const documentSessions = new Map();
@@ -255,7 +255,7 @@ function registerDataViewPanel(
         }
         dynamicDataViewPanels.delete(key);
         // Interactive transcripts retain this handle after the expanded viewer closes.
-        if (sessions.get(sessionId ?? '')?.requester) { return; }
+        if (currentStateGeneration === undefined && sessions.get(sessionId ?? '')?.requester) { return; }
         void sessionRequest({
             method: 'dataview_dispose',
             params: { view_id: viewId, state_generation: currentStateGeneration },
diff --git a/src/test/suite/dataViewerSessions.test.ts b/src/test/suite/dataViewerSessions.test.ts
index 42e2bbeac..495676bdd 100644
--- a/src/test/suite/dataViewerSessions.test.ts
+++ b/src/test/suite/dataViewerSessions.test.ts
@@ -127,7 +127,7 @@ suite('Viewer session ownership', () => {
             socket.once('error', reject);
         });
         notify(client, 'attach', {
-            protocol_version: 1, session_id: id, host: 'viewer-test-host', pid: id,
+            protocol_version: 2, session_id: id, host: 'viewer-test-host', pid: id,
             version: '4.6.0', tempdir: '/tmp', wd: '/tmp',
         });
         await waitFor(() => session.activeSession?.sessionId === id &&
@@ -201,6 +201,28 @@ suite('Viewer session ownership', () => {
         await open(a, 'table', aTable);
     });
 
+    test('Interactive viewers retain transcript tables and dispose standalone list state', async () => {
+        const request = sandbox.stub().resolves({ columns: [], totalRows: 1 });
+        const owner = session.registerSessionTransport('interactive-viewer', 'host', '/tmp', request);
+        try {
+            const other = await attach('other-viewer-session');
+            await session.showDataView('table', 'json', 'table', '', 'Two', 'transcript-table', undefined, owner.sessionId);
+            await send(panels[0], { message: 'dataview/request', action: 'init' });
+            sinon.assert.calledWithExactly(request, { method: 'dataview_init', params: { view_id: 'transcript-table' } });
+            request.resetHistory();
+            panels[0].panel.dispose();
+            sinon.assert.notCalled(request);
+            await session.showDataView('list', 'json', 'list', '', 'Two', 'standalone-list', undefined, owner.sessionId, 3);
+            panels[1].panel.dispose();
+            sinon.assert.calledOnceWithExactly(request, {
+                method: 'dataview_dispose', params: { view_id: 'standalone-list', state_generation: 3 },
+            });
+            assert.deepStrictEqual(viewerRequests(other), []);
+        } finally {
+            session.unregisterSessionTransport(owner);
+        }
+    });
+
     test('viewers follow the same session on reconnect and never fall back after disconnect', async () => {
         const a = await attach('viewer-reconnect-a');
         const list = await open(a, 'list');
diff --git a/src/test/suite/interactiveEditor.test.ts b/src/test/suite/interactiveEditor.test.ts
index e1d344d0f..566c82541 100644
--- a/src/test/suite/interactiveEditor.test.ts
+++ b/src/test/suite/interactiveEditor.test.ts
@@ -1179,6 +1179,34 @@ cat("\n")`;
             sinon.assert.notCalled(errors);
         } finally { errors.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;
+        const panels: vscode.WebviewPanel[] = [];
+        const receivers: sinon.SinonSpy[] = [];
+        const create = sinon.stub(vscode.window, 'createWebviewPanel').callsFake((type, title, column, options) => {
+            const panel = original(type, title, column, options);
+            panels.push(panel);
+            receivers.push(sinon.spy(panel.webview, 'onDidReceiveMessage'));
+            return panel;
+        });
+        try {
+            await vscode.commands.executeCommand('r.runSelection', 'rebase_view <- list(table=data.frame(value=1:2)); 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]);
+            const receive = receivers[0].firstCall.args[0] as (message: unknown) => Promise;
+            const documentGeneration = Number(/const documentGeneration = (\d+)/.exec(panels[0].webview.html)?.[1]);
+            await receive({ message: 'listview/view', documentGeneration, requestId: 1, path: [], index: 1 });
+            await until(() => panels.length === 2);
+            assert.strictEqual(panels[1].title, 'rebase_view$table');
+        } finally {
+            panels.forEach(panel => { panel.dispose(); });
+            receivers.forEach(receiver => { receiver.restore(); });
+            create.restore();
+        }
+    });
+
     test('large native cells export their snapshot scope and open the full data viewer', 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);
diff --git a/src/test/suite/session.test.ts b/src/test/suite/session.test.ts
index 9194d4730..75ecb71d9 100644
--- a/src/test/suite/session.test.ts
+++ b/src/test/suite/session.test.ts
@@ -276,7 +276,7 @@ suite('Session Communication', () => {
 
         const connection = await api.getConnectionInfo();
         assert.ok(connection);
-        assert.strictEqual(connection.protocolVersion, 1);
+        assert.strictEqual(connection.protocolVersion, 2);
         assert.strictEqual(connection.endpoint, session.globalPipePath);
         assert.strictEqual(connection.plotBackend, 'standard');
         assert.ok(!('socket' in connection), 'connection info should contain plain contract data only');
@@ -315,7 +315,7 @@ suite('Session Communication', () => {
                 jsonrpc: '2.0',
                 method: 'attach',
                 params: {
-                    protocol_version: 1,
+                    protocol_version: 2,
                     session_id: id,
                     host: 'test-remote-host',
                     version: '4.4.0',
@@ -651,7 +651,7 @@ suite('Session Communication', () => {
                     const id = `reconnected-${terminalPid}`;
                     client.write(`${JSON.stringify({
                         jsonrpc: '2.0', method: 'attach', params: {
-                            protocol_version: 1, session_id: id, host: os.hostname(),
+                            protocol_version: 2, session_id: id, host: os.hostname(),
                             pid: terminalPid, version: '4.4.0', tempdir: '/tmp', wd: '/tmp',
                         },
                     })}\n`);
@@ -709,7 +709,7 @@ suite('Session Communication', () => {
             });
             client.write(`${JSON.stringify({
                 jsonrpc: '2.0', method: 'attach', params: {
-                    protocol_version: 1, session_id: 'manual-recovery-first',
+                    protocol_version: 2, session_id: 'manual-recovery-first',
                     host: os.hostname(), pid: 45240, version: '4.5.0',
                     tempdir: os.tmpdir(), wd: os.tmpdir(),
                     info: { version: 'R 4.5.0', command: 'R', start_time: '' },
@@ -866,7 +866,7 @@ suite('Session Communication', () => {
                 jsonrpc: '2.0',
                 method: 'attach',
                 params: {
-                    protocol_version: 1,
+                    protocol_version: 2,
                     session_id: 'stable-session-id',
                     host: 'remote-compute-node',
                     sess_version: '3.0.0',
@@ -914,7 +914,7 @@ suite('Session Communication', () => {
                 jsonrpc: '2.0',
                 method: 'attach',
                 params: {
-                    protocol_version: 1,
+                    protocol_version: 2,
                     session_id: 'other-session-id',
                     host: 'other-compute-node',
                     sess_version: '3.0.0',
@@ -949,7 +949,7 @@ suite('Session Communication', () => {
             jsonrpc: '2.0',
             method: 'attach',
             params: {
-                protocol_version: 1,
+                protocol_version: 2,
                 session_id: sessionId,
                 host: 'remote-compute-node',
                 sess_version: '3.0.0',
@@ -997,11 +997,11 @@ suite('Session Communication', () => {
             client.write(`${JSON.stringify({
                 jsonrpc: '2.0',
                 method: 'attach',
-                params: { protocol_version: 2, session_id: 'future-session' }
+                params: { protocol_version: 1, session_id: 'legacy-session' }
             })}\n`);
             await waitFor(() => showError.called);
-            assert.match(String(showError.firstCall.args[0]), /unsupported sess protocol version 2/);
-            assert.notStrictEqual(session.activeSession?.sessionId, 'future-session');
+            assert.match(String(showError.firstCall.args[0]), /unsupported sess protocol version 1; this extension requires protocol version 2/);
+            assert.notStrictEqual(session.activeSession?.sessionId, 'legacy-session');
         } finally {
             client.destroy();
         }
diff --git a/src/test/suite/workspaceViewer.test.ts b/src/test/suite/workspaceViewer.test.ts
index 8bec4cfc1..ab0c4e13d 100644
--- a/src/test/suite/workspaceViewer.test.ts
+++ b/src/test/suite/workspaceViewer.test.ts
@@ -113,6 +113,25 @@ suite('Workspace Viewer', () => {
         sinon.assert.notCalled(second.execute as sinon.SinonStub);
     });
 
+    test('nested View keeps the originating session after focus changes', async () => {
+        session.updateSessionWorkspace(first, data('nested'));
+        const request = sandbox.stub().resolves({ children: [{
+            str: '$ table', class: 'data.frame', type: 'list', has_children: true,
+            viewable: true, selector: { kind: 'index', value: 1 },
+        }] });
+        first.requester = request;
+        const children = await provider.getChildren((await envNodes())[0]);
+        const child = children[0] as workspace.GlobalEnvItem;
+        assert.strictEqual(child.contextValue, 'viewableNode');
+        await session.activateSession(second);
+        request.resetHistory();
+        await workspace.viewItem(child);
+        sinon.assert.calledOnceWithExactly(request, {
+            method: 'workspace_view', params: { name: 'nested', path: [{ kind: 'index', value: 1 }] },
+        });
+        sinon.assert.notCalled(second.execute as sinon.SinonStub);
+    });
+
     test('clear confirmation captures the displayed session before switching', async () => {
         const prompt = sandbox.stub(vscode.window, 'showInformationMessage').callsFake(async () => {
             await session.activateSession(second);
diff --git a/src/workspaceViewer.ts b/src/workspaceViewer.ts
index a1583253a..78cae3a71 100644
--- a/src/workspaceViewer.ts
+++ b/src/workspaceViewer.ts
@@ -496,6 +496,10 @@ export async function loadWorkspace(): Promise {
 
 export async function viewItem(node: GlobalEnvItem): Promise {
     if (node.owner && !node.owner.workspaceUnavailable && node.rootName) {
+        if (!node.objectPath.length) {
+            await runWorkspaceCode(`View(get(${JSON.stringify(node.rootName)}, envir = .GlobalEnv, inherits = FALSE), title = ${JSON.stringify(node.rootName)})`, node.owner);
+            return;
+        }
         await sessionRequest({
             method: 'workspace_view',
             params: { name: node.rootName, path: node.objectPath },

From be2dc6a7a6f89d037f3e33c392d67d417c3b27f8 Mon Sep 17 00:00:00 2001
From: "4111978+Fred-Wu@users.noreply.github.com"
 <4111978+Fred-Wu@users.noreply.github.com>
Date: Mon, 5 Oct 2026 10:18:36 +1100
Subject: [PATCH 25/30] refactor(viewer): use packaged codicons and consolidate
 icon notices

Replace copied List Viewer control SVGs with @vscode/codicons.
Bundle its CSS, font, and licenses.
Move attribution from README into third-party notices covering
Codicons, existing viewer tab icons, and the R logo.
---
 .vscodeignore                               | 12 ++++++
 README.md                                   |  4 --
 ThirdPartyNotices.txt                       | 32 ++++++++++++++
 esbuild.js                                  |  6 ++-
 images/icons/arrow-left.svg                 |  3 --
 images/icons/chevron-down.svg               |  3 --
 images/icons/chevron-right.svg              |  3 --
 images/icons/dark/open-preview-codicon.svg  |  1 -
 images/icons/light/open-preview-codicon.svg |  1 -
 package.json                                |  1 +
 pnpm-lock.yaml                              |  8 ++++
 src/listViewer.ts                           |  9 ++--
 src/session.ts                              | 47 ++++-----------------
 src/test/suite/listViewer.test.ts           |  2 +-
 src/test/suite/listViewerPanels.test.ts     |  4 +-
 15 files changed, 75 insertions(+), 61 deletions(-)
 create mode 100644 ThirdPartyNotices.txt
 delete mode 100644 images/icons/arrow-left.svg
 delete mode 100644 images/icons/chevron-down.svg
 delete mode 100644 images/icons/chevron-right.svg
 delete mode 100644 images/icons/dark/open-preview-codicon.svg
 delete mode 100644 images/icons/light/open-preview-codicon.svg

diff --git a/.vscodeignore b/.vscodeignore
index 9837514aa..2dd953f64 100644
--- a/.vscodeignore
+++ b/.vscodeignore
@@ -3,11 +3,17 @@
 !README.md
 !CHANGELOG.md
 !LICENSE
+<<<<<<< HEAD
 !R/*.R
 !R/cppProperties/**
 !R/help/**
 !R/rmarkdown/**
 !R/template/**
+=======
+!ThirdPartyNotices.txt
+!R/**
+!sess/**
+>>>>>>> 109dc25 (refactor(viewer): use packaged codicons and consolidate icon notices)
 !html/**/*.ejs
 !html/**/*.css
 !html/**/*.js
@@ -18,4 +24,10 @@
 !dist/**/*.js
 !dist/**/*.css
 !dist/**/*.ejs
+<<<<<<< HEAD
 !dist/resources/sess/**
+=======
+!dist/resources/codicon.ttf
+!dist/resources/LICENSE
+!dist/resources/LICENSE-CODE
+>>>>>>> 109dc25 (refactor(viewer): use packaged codicons and consolidate icon notices)
diff --git a/README.md b/README.md
index 5f2c13bf1..a226fd305 100644
--- a/README.md
+++ b/README.md
@@ -138,7 +138,3 @@ Call `View(x)` to open a table. The viewer loads rows on demand and applies colu
 ## Persistent R Interactive
 
 This experimental feature provides native VS Code Interactive windows with independent plain-R or arf sessions, including adoption of existing arf sessions over Remote SSH. See the [setup and usage guide](https://github.com/REditorSupport/vscode-R/wiki/R-Interactive) for session switching, persistence, rich outputs, and platform requirements.
-
-## Icon attribution
-
-The list viewer’s navigation and chevron icons are from Microsoft’s [VS Code Codicons](https://github.com/microsoft/vscode-codicons), licensed under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). The icon artwork is unchanged.
diff --git a/ThirdPartyNotices.txt b/ThirdPartyNotices.txt
new file mode 100644
index 000000000..a81ca18c7
--- /dev/null
+++ b/ThirdPartyNotices.txt
@@ -0,0 +1,32 @@
+VS Code Codicons (@vscode/codicons)
+Copyright (c) Microsoft Corporation.
+Source: https://github.com/microsoft/vscode-codicons
+
+The List Viewer uses the package's CSS and icon font. The icon artwork is
+unchanged.
+
+The extension also includes SVG copies of the open-preview, preview, globe,
+graph and help icons in images/icons/dark and images/icons/light, with colors
+set for the corresponding themes. These are used for viewer tab icons,
+including the Data Viewer and List Viewer.
+Original integration: https://github.com/REditorSupport/vscode-R/pull/759
+
+The artwork is licensed under Creative Commons Attribution 4.0 International:
+https://creativecommons.org/licenses/by/4.0/
+The package's code is licensed under the MIT License.
+
+The bundled license texts are in dist/resources/LICENSE (CC BY 4.0) and
+dist/resources/LICENSE-CODE (MIT). These files apply to Codicons.
+
+
+R logo
+Copyright (c) 2016 The R Foundation.
+Source: https://www.r-project.org/logo/
+
+Files: images/Rlogo.svg and images/Rlogo.png.
+The SVG reproduces the official artwork unchanged. The PNG is an 800 x 700
+raster variant used as the extension icon.
+
+The logo is distributed under Creative Commons Attribution-ShareAlike 4.0
+International:
+https://creativecommons.org/licenses/by-sa/4.0/
diff --git a/esbuild.js b/esbuild.js
index 29df03330..cfa0d554b 100644
--- a/esbuild.js
+++ b/esbuild.js
@@ -12,7 +12,11 @@ function copyResources() {
     const resources = [
         './node_modules/ag-grid-community/dist/ag-grid-community.min.noStyle.js',
         './node_modules/ag-grid-community/styles/ag-grid.min.css',
-        './node_modules/ag-grid-community/styles/ag-theme-balham.min.css'
+        './node_modules/ag-grid-community/styles/ag-theme-balham.min.css',
+        './node_modules/@vscode/codicons/dist/codicon.css',
+        './node_modules/@vscode/codicons/dist/codicon.ttf',
+        './node_modules/@vscode/codicons/LICENSE',
+        './node_modules/@vscode/codicons/LICENSE-CODE'
     ];
 
     for (const res of resources) {
diff --git a/images/icons/arrow-left.svg b/images/icons/arrow-left.svg
deleted file mode 100644
index 91773a7ec..000000000
--- a/images/icons/arrow-left.svg
+++ /dev/null
@@ -1,3 +0,0 @@
-
-
\ No newline at end of file
diff --git a/images/icons/chevron-down.svg b/images/icons/chevron-down.svg
deleted file mode 100644
index 389873c46..000000000
--- a/images/icons/chevron-down.svg
+++ /dev/null
@@ -1,3 +0,0 @@
-
-
\ No newline at end of file
diff --git a/images/icons/chevron-right.svg b/images/icons/chevron-right.svg
deleted file mode 100644
index d08afa0b5..000000000
--- a/images/icons/chevron-right.svg
+++ /dev/null
@@ -1,3 +0,0 @@
-
-
\ No newline at end of file
diff --git a/images/icons/dark/open-preview-codicon.svg b/images/icons/dark/open-preview-codicon.svg
deleted file mode 100644
index 5dc0bba6b..000000000
--- a/images/icons/dark/open-preview-codicon.svg
+++ /dev/null
@@ -1 +0,0 @@
-
diff --git a/images/icons/light/open-preview-codicon.svg b/images/icons/light/open-preview-codicon.svg
deleted file mode 100644
index 9e363217a..000000000
--- a/images/icons/light/open-preview-codicon.svg
+++ /dev/null
@@ -1 +0,0 @@
-
diff --git a/package.json b/package.json
index b7ea83415..abd3e8a22 100644
--- a/package.json
+++ b/package.json
@@ -2566,6 +2566,7 @@
     "typescript": "~5.8.3"
   },
   "dependencies": {
+    "@vscode/codicons": "0.0.46-24",
     "ag-grid-community": "^36.2.0",
     "cheerio": "1.0.0-rc.12",
     "crypto": "^1.0.1",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index a9078eafa..98e84f028 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -8,6 +8,9 @@ importers:
 
   .:
     dependencies:
+      '@vscode/codicons':
+        specifier: 0.0.46-24
+        version: 0.0.46-24
       ag-grid-community:
         specifier: ^36.2.0
         version: 36.2.0
@@ -749,6 +752,9 @@ packages:
     resolution: {integrity: sha512-edSdeAqkdxBVzA1yL1LrLCml1YjyCVvPMtMqJpbF+6K609tHe8V6sQUzFQSGcYNhcuhOceZtjvN32+mpIth30A==}
     engines: {node: '>=22.0.0'}
 
+  '@vscode/codicons@0.0.46-24':
+    resolution: {integrity: sha512-KIDWUYxG6eh+DHRg+3G4bS487T+g1ZkLfB4HylOBbCcHsvLdfLMRM/m92DS1Ljhi8nglLr9ucwwWhHTEAC+DpA==}
+
   '@vscode/test-cli@0.0.12':
     resolution: {integrity: sha512-iYN0fDg29+a2Xelle/Y56Xvv7Nc8Thzq4VwpzAF/SIE6918rDicqfsQxV6w1ttr2+SOm+10laGuY9FG2ptEKsQ==}
     engines: {node: '>=18'}
@@ -3252,6 +3258,8 @@ snapshots:
     transitivePeerDependencies:
       - supports-color
 
+  '@vscode/codicons@0.0.46-24': {}
+
   '@vscode/test-cli@0.0.12':
     dependencies:
       '@types/mocha': 10.0.10
diff --git a/src/listViewer.ts b/src/listViewer.ts
index f680ebe9a..a1aaa09e8 100644
--- a/src/listViewer.ts
+++ b/src/listViewer.ts
@@ -46,7 +46,7 @@ export function getListViewerScript(documentGeneration: number, initial: ListVie
         navigation.breadcrumbs.forEach((crumb, index) => {
             if (index) {
                 const separator = document.createElement('span');
-                separator.className = 'breadcrumb-separator';
+                separator.className = 'codicon codicon-chevron-right';
                 separator.setAttribute('aria-hidden', 'true');
                 breadcrumbs.appendChild(separator);
             }
@@ -119,7 +119,7 @@ export function getListViewerScript(documentGeneration: number, initial: ListVie
                     row.className = 'item';
                     if (!vector) {
                         const arrow = document.createElement('span');
-                        arrow.className = 'arrow';
+                        arrow.className = expandable ? 'arrow codicon codicon-chevron-right' : 'arrow';
                         arrow.setAttribute('aria-hidden', 'true');
                         row.appendChild(arrow);
                     }
@@ -136,7 +136,10 @@ export function getListViewerScript(documentGeneration: number, initial: ListVie
                         const button = document.createElement('button');
                         button.title = 'View';
                         button.setAttribute('aria-label', 'View ' + item.label);
-                        button.innerHTML = document.getElementById('view-icon').innerHTML;
+                        const icon = document.createElement('span');
+                        icon.className = 'codicon codicon-open-preview';
+                        icon.setAttribute('aria-hidden', 'true');
+                        button.appendChild(icon);
                         button.addEventListener('click', (event) => {
                             event.preventDefault();
                             event.stopPropagation();
diff --git a/src/session.ts b/src/session.ts
index 2e5553f48..a01dc9125 100644
--- a/src/session.ts
+++ b/src/session.ts
@@ -1103,7 +1103,7 @@ export async function showDataView(
                 enableScripts: true,
                 enableFindWidget: true,
                 retainContextWhenHidden: true,
-                localResourceRoots: [Uri.file(extensionContext.asAbsolutePath('images/icons'))],
+                localResourceRoots: [Uri.file(resDir)],
             });
         panel.iconPath = new UriIcon('preview');
         if (viewId) {
@@ -1876,17 +1876,8 @@ export function getListHtml(
 ): string {
     const documentGeneration = ++documentGenerationRevision;
     documentGenerations.set(webview, documentGeneration);
-    const icon = new UriIcon('open-preview-codicon');
-    const darkIcon = webview.asWebviewUri(icon.dark).toString();
-    const lightIcon = webview.asWebviewUri(icon.light).toString();
-    const chevronIcon = webview.asWebviewUri(
-        Uri.file(extensionContext.asAbsolutePath('images/icons/chevron-right.svg'))
-    ).toString();
-    const backIcon = webview.asWebviewUri(
-        Uri.file(extensionContext.asAbsolutePath('images/icons/arrow-left.svg'))
-    ).toString();
-    const expandedChevronIcon = webview.asWebviewUri(
-        Uri.file(extensionContext.asAbsolutePath('images/icons/chevron-down.svg'))
+    const codicons = webview.asWebviewUri(
+        Uri.file(path.join(resDir, 'codicon.css'))
     ).toString();
 
     return `
@@ -1896,6 +1887,7 @@ export function getListHtml(
     
     
     ${escapeHtml(title)}
+    
     
 
 
     

-        
+        
         
     

     
     

-