feat(web): pin Logging/History/Network as a resizable column (#1616)

Add the ability to "pin" the Logging, History, and Network screens into a
second column on the right of the InspectorView, so a primary screen and a
monitor screen are visible at once (e.g. watch Logs while calling a Tool).

- A "pin as column" button on the Logs/History/Network panel toolbars opens
  the column (shown only when wide + connected).
- The column hosts a MonitoringControls tab row (available monitor tabs +
  close) over the selected embedded screen. Pinning removes the monitor group
  from the header tab bar; closing (x) returns it.
- The divider between the primary area and the column is draggable (pointer +
  keyboard); width is clamped and persisted.
- The split collapses to one column below ~1040px (the ServerListScreen
  single-card breakpoint) and while disconnected, without discarding the pin
  preference — it reopens when wide + connected again.

State (pinned/tab/width) is view-local and persisted via the existing
useLocalStorage pattern, so no new props thread through App and ViewHeader is
unchanged (it just receives a filtered tab list). Screens/panels gain an
`embedded` mode (fills the parent height, drops the 340px filter sidebar) via a
shared EmbeddableScrollArea element.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/web/src/components/groups/HistoryListPanel/HistoryListPanel.tsx

@@ -4,7 +4,6 @@ import {
   Collapse,
   Group,
   Paper,
-  ScrollArea,
   Stack,
   Text,
   Title,
@@ -21,6 +20,8 @@ import {
   SortToggle,
   type SortDirection,
 } from "../../elements/SortToggle/SortToggle";
+import { PinColumnButton } from "../../elements/PinColumnButton/PinColumnButton";
+import { EmbeddableScrollArea } from "../../elements/EmbeddableScrollArea/EmbeddableScrollArea";
 import { extractMethod } from "../historyUtils.js";
 import { useScrollMemory } from "../../../hooks/useScrollMemory";
 
@@ -43,6 +44,10 @@ export interface HistoryListPanelProps {
   onSortChange: (next: SortDirection) => void;
   compact: boolean;
   onToggleCompact: () => void;
+  /** See LogStreamPanel: shows a "pin as column" button when set (#1616). */
+  onPin?: () => void;
+  /** See LogStreamPanel: fills the flex parent instead of the viewport calc. */
+  embedded?: boolean;
 }
 
 const PanelContainer = Paper.withProps({
@@ -201,6 +206,8 @@ export function HistoryListPanel({
   onSortChange,
   compact,
   onToggleCompact,
+  onPin,
+  embedded = false,
 }: HistoryListPanelProps) {
   const viewportRef = useScrollMemory("history-list");
   // Per-section expand/collapse, like the LogControls level toggles. Both start
@@ -238,6 +245,7 @@ export function HistoryListPanel({
       <Group justify="space-between" mb="sm">
         <Title order={4}>Requests</Title>
         <Group gap="xs">
+          {onPin ? <PinColumnButton onPin={onPin} /> : null}
           {hasResults && (
             <ListToggle compact={compact} onToggle={onToggleCompact} />
           )}
@@ -262,12 +270,7 @@ export function HistoryListPanel({
       {!hasResults ? (
         <EmptyState>No request history</EmptyState>
       ) : (
-        <ScrollArea.Autosize
-          viewportRef={viewportRef}
-          mah="calc(100vh - var(--app-shell-header-height, 0px) - 150px)"
-          type="scroll"
-          offsetScrollbars
-        >
+        <EmbeddableScrollArea embedded={embedded} viewportRef={viewportRef}>
           <Stack gap="md">
             {pinnedEntries.length > 0 && (
               <CollapsibleSection
@@ -325,7 +328,7 @@ export function HistoryListPanel({
               </CollapsibleSection>
             )}
           </Stack>
-        </ScrollArea.Autosize>
+        </EmbeddableScrollArea>
       )}
     </PanelContainer>
   );

clients/web/src/components/groups/LogStreamPanel/LogStreamPanel.tsx

@@ -1,13 +1,5 @@
 import { useMemo } from "react";
-import {
-  Button,
-  Group,
-  Paper,
-  ScrollArea,
-  Stack,
-  Text,
-  Title,
-} from "@mantine/core";
+import { Button, Group, Paper, Stack, Text, Title } from "@mantine/core";
 import type { LoggingLevel } from "@modelcontextprotocol/sdk/types.js";
 import { LogEntry } from "../../elements/LogEntry/LogEntry";
 import type { LogEntryData } from "../../elements/LogEntry/LogEntry";
@@ -15,6 +7,8 @@ import {
   SortToggle,
   type SortDirection,
 } from "../../elements/SortToggle/SortToggle";
+import { PinColumnButton } from "../../elements/PinColumnButton/PinColumnButton";
+import { EmbeddableScrollArea } from "../../elements/EmbeddableScrollArea/EmbeddableScrollArea";
 import { useScrollMemory } from "../../../hooks/useScrollMemory";
 
 export interface LogStreamPanelProps {
@@ -25,6 +19,18 @@ export interface LogStreamPanelProps {
   onExport: () => void;
   sortDirection: SortDirection;
   onSortChange: (next: SortDirection) => void;
+  /**
+   * When set, renders a "pin as column" button in the toolbar that opens this
+   * screen in the monitoring column (#1616). Omitted when the panel is already
+   * embedded in that column (or when pinning isn't available).
+   */
+  onPin?: () => void;
+  /**
+   * True when this panel is rendered inside the monitoring column. Switches the
+   * scroll region from the viewport-height calc to filling its flex parent, so
+   * it fits below the column's controls row without viewport math.
+   */
+  embedded?: boolean;
 }
 
 const PanelContainer = Paper.withProps({
@@ -69,6 +75,8 @@ export function LogStreamPanel({
   onExport,
   sortDirection,
   onSortChange,
+  onPin,
+  embedded = false,
 }: LogStreamPanelProps) {
   const viewportRef = useScrollMemory("logs-stream");
   const filteredEntries = useMemo(() => {
@@ -85,6 +93,7 @@ export function LogStreamPanel({
       <Group justify="space-between" mb="sm">
         <Title order={4}>Log Stream</Title>
         <Group>
+          {onPin ? <PinColumnButton onPin={onPin} /> : null}
           <SortToggle
             value={sortDirection}
             onChange={onSortChange}
@@ -107,18 +116,13 @@ export function LogStreamPanel({
         </Group>
       </Group>
       {filteredEntries.length > 0 ? (
-        <ScrollArea.Autosize
-          viewportRef={viewportRef}
-          mah="calc(100vh - var(--app-shell-header-height, 0px) - 150px)"
-          type="scroll"
-          offsetScrollbars
-        >
+        <EmbeddableScrollArea embedded={embedded} viewportRef={viewportRef}>
           <Stack gap="xs">
             {filteredEntries.map((entry, index) => (
               <LogEntry key={index} entry={entry} />
             ))}
           </Stack>
-        </ScrollArea.Autosize>
+        </EmbeddableScrollArea>
       ) : (
         <EmptyCenter>
           <Text c="dimmed">No log entries</Text>

clients/web/src/components/groups/MonitoringControls/MonitoringControls.stories.tsx

@@ -0,0 +1,35 @@
+import type { Meta, StoryObj } from "@storybook/react-vite";
+import { expect, fn, within } from "storybook/test";
+import { MonitoringControls } from "./MonitoringControls";
+
+const meta: Meta<typeof MonitoringControls> = {
+  title: "Groups/MonitoringControls",
+  component: MonitoringControls,
+  args: {
+    tabs: ["Logs", "History", "Network"],
+    value: "Logs",
+    onChange: fn(),
+    onClose: fn(),
+  },
+};
+
+export default meta;
+type Story = StoryObj<typeof MonitoringControls>;
+
+export const AllTabs: Story = {
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    expect(canvas.getByRole("radio", { name: "Logs" })).toBeChecked();
+    expect(
+      canvas.getByRole("button", { name: "Close monitoring column" }),
+    ).toBeInTheDocument();
+  },
+};
+
+export const StdioServer: Story = {
+  args: { tabs: ["Logs", "History"], value: "History" },
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    expect(canvas.queryByRole("radio", { name: "Network" })).toBeNull();
+  },
+};

clients/web/src/components/groups/MonitoringControls/MonitoringControls.test.tsx

@@ -0,0 +1,79 @@
+import { describe, it, expect, vi } from "vitest";
+import userEvent from "@testing-library/user-event";
+import { renderWithMantine, screen } from "../../../test/renderWithMantine";
+import { MonitoringControls } from "./MonitoringControls";
+
+const TABS = ["Logs", "History", "Network"];
+
+describe("MonitoringControls", () => {
+  it("renders a radio option for each available tab", () => {
+    renderWithMantine(
+      <MonitoringControls
+        tabs={TABS}
+        value="Logs"
+        onChange={vi.fn()}
+        onClose={vi.fn()}
+      />,
+    );
+    for (const tab of TABS) {
+      expect(screen.getByRole("radio", { name: tab })).toBeInTheDocument();
+    }
+  });
+
+  it("renders only the tabs it is given", () => {
+    renderWithMantine(
+      <MonitoringControls
+        tabs={["Logs", "History"]}
+        value="Logs"
+        onChange={vi.fn()}
+        onClose={vi.fn()}
+      />,
+    );
+    expect(screen.getAllByRole("radio")).toHaveLength(2);
+    expect(screen.queryByRole("radio", { name: "Network" })).toBeNull();
+  });
+
+  it("marks the active tab as selected", () => {
+    renderWithMantine(
+      <MonitoringControls
+        tabs={TABS}
+        value="History"
+        onChange={vi.fn()}
+        onClose={vi.fn()}
+      />,
+    );
+    expect(screen.getByRole("radio", { name: "History" })).toBeChecked();
+  });
+
+  it("calls onChange when a different tab is chosen", async () => {
+    const user = userEvent.setup();
+    const onChange = vi.fn();
+    renderWithMantine(
+      <MonitoringControls
+        tabs={TABS}
+        value="Logs"
+        onChange={onChange}
+        onClose={vi.fn()}
+      />,
+    );
+    await user.click(screen.getByRole("radio", { name: "Network" }));
+    expect(onChange).toHaveBeenCalledWith("Network");
+  });
+
+  it("calls onClose when the close button is clicked", async () => {
+    const user = userEvent.setup();
+    const onClose = vi.fn();
+    renderWithMantine(
+      <MonitoringControls
+        tabs={TABS}
+        value="Logs"
+        onChange={vi.fn()}
+        onClose={onClose}
+      />,
+    );
+    await user.click(
+      screen.getByRole("button", { name: "Close monitoring column" }),
+    );
+    expect(onClose).toHaveBeenCalledTimes(1);
+  });
+});

clients/web/src/components/groups/MonitoringControls/MonitoringControls.tsx

@@ -0,0 +1,46 @@
+import { CloseButton, Group, SegmentedControl } from "@mantine/core";
+
+export interface MonitoringControlsProps {
+  /** The monitor screens currently available to pin (e.g. Logs/History/Network). */
+  tabs: string[];
+  /** The active monitor tab shown in the column below. */
+  value: string;
+  onChange: (tab: string) => void;
+  /** Close the monitoring column, returning its screens to the header menu. */
+  onClose: () => void;
+}
+
+// The controls row that sits at the top of the pinned monitoring column: a
+// segmented tab switcher on the left, a close button on the right that unpins
+// the whole column.
+const ControlsBar = Group.withProps({
+  justify: "space-between",
+  wrap: "nowrap",
+  gap: "sm",
+  p: "sm",
+});
+
+/**
+ * Tab row + close control for the pinned monitoring column (#1616). Renders only
+ * the currently-available monitor tabs (the caller filters by capability), so it
+ * never shows an empty switcher. Selecting a tab swaps the screen below; the
+ * close button unpins the column so its screens rejoin the header tab menu.
+ */
+export function MonitoringControls({
+  tabs,
+  value,
+  onChange,
+  onClose,
+}: MonitoringControlsProps) {
+  return (
+    <ControlsBar>
+      <SegmentedControl
+        size="sm"
+        value={value}
+        onChange={onChange}
+        data={tabs}
+      />
+      <CloseButton aria-label="Close monitoring column" onClick={onClose} />
+    </ControlsBar>
+  );
+}

clients/web/src/components/groups/MonitoringScreen/MonitoringScreen.stories.tsx

@@ -0,0 +1,59 @@
+import { Box, Text } from "@mantine/core";
+import type { Meta, StoryObj } from "@storybook/react-vite";
+import { expect, fn, within } from "storybook/test";
+import { MonitoringScreen } from "./MonitoringScreen";
+
+const demoScreens = {
+  Logs: (
+    <Box p="md">
+      <Text>Log stream</Text>
+    </Box>
+  ),
+  History: (
+    <Box p="md">
+      <Text>Request history</Text>
+    </Box>
+  ),
+  Network: (
+    <Box p="md">
+      <Text>Network requests</Text>
+    </Box>
+  ),
+};
+
+const meta: Meta<typeof MonitoringScreen> = {
+  title: "Groups/MonitoringScreen",
+  component: MonitoringScreen,
+  decorators: [
+    (Story) => (
+      <Box h={320}>
+        <Story />
+      </Box>
+    ),
+  ],
+  args: {
+    tabs: ["Logs", "History", "Network"],
+    value: "Logs",
+    onChange: fn(),
+    onClose: fn(),
+    screens: demoScreens,
+  },
+};
+
+export default meta;
+type Story = StoryObj<typeof MonitoringScreen>;
+
+export const Logs: Story = {
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    expect(canvas.getByText("Log stream")).toBeInTheDocument();
+  },
+};
+
+export const History: Story = {
+  args: { value: "History" },
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    expect(canvas.getByText("Request history")).toBeInTheDocument();
+  },
+};

clients/web/src/components/groups/MonitoringScreen/MonitoringScreen.test.tsx

@@ -0,0 +1,81 @@
+import { describe, it, expect, vi } from "vitest";
+import userEvent from "@testing-library/user-event";
+import { renderWithMantine, screen } from "../../../test/renderWithMantine";
+import { MonitoringScreen } from "./MonitoringScreen";
+
+const TABS = ["Logs", "History", "Network"];
+
+function screens() {
+  return {
+    Logs: <div>logs-body</div>,
+    History: <div>history-body</div>,
+    Network: <div>network-body</div>,
+  };
+}
+
+describe("MonitoringScreen", () => {
+  it("renders the screen for the active tab", () => {
+    renderWithMantine(
+      <MonitoringScreen
+        tabs={TABS}
+        value="History"
+        onChange={vi.fn()}
+        onClose={vi.fn()}
+        screens={screens()}
+      />,
+    );
+    expect(screen.getByText("history-body")).toBeInTheDocument();
+    expect(screen.queryByText("logs-body")).toBeNull();
+    expect(screen.queryByText("network-body")).toBeNull();
+  });
+
+  it("renders the controls tab row", () => {
+    renderWithMantine(
+      <MonitoringScreen
+        tabs={TABS}
+        value="Logs"
+        onChange={vi.fn()}
+        onClose={vi.fn()}
+        screens={screens()}
+      />,
+    );
+    expect(screen.getByRole("radio", { name: "Logs" })).toBeInTheDocument();
+    expect(
+      screen.getByRole("button", { name: "Close monitoring column" }),
+    ).toBeInTheDocument();
+  });
+
+  it("forwards tab changes and close from the controls", async () => {
+    const user = userEvent.setup();
+    const onChange = vi.fn();
+    const onClose = vi.fn();
+    renderWithMantine(
+      <MonitoringScreen
+        tabs={TABS}
+        value="Logs"
+        onChange={onChange}
+        onClose={onClose}
+        screens={screens()}
+      />,
+    );
+    await user.click(screen.getByRole("radio", { name: "Network" }));
+    expect(onChange).toHaveBeenCalledWith("Network");
+    await user.click(
+      screen.getByRole("button", { name: "Close monitoring column" }),
+    );
+    expect(onClose).toHaveBeenCalledTimes(1);
+  });
+
+  it("renders nothing in the slot when the active tab has no screen", () => {
+    renderWithMantine(
+      <MonitoringScreen
+        tabs={TABS}
+        value="Network"
+        onChange={vi.fn()}
+        onClose={vi.fn()}
+        screens={{ Logs: <div>logs-body</div> }}
+      />,
+    );
+    expect(screen.queryByText("logs-body")).toBeNull();
+  });
+});

clients/web/src/components/groups/MonitoringScreen/MonitoringScreen.tsx

@@ -0,0 +1,56 @@
+import type { ReactNode } from "react";
+import { Divider, Stack } from "@mantine/core";
+import { MonitoringControls } from "../MonitoringControls/MonitoringControls";
+
+export interface MonitoringScreenProps {
+  /** Available monitor tabs (Logs/History/Network, filtered by capability). */
+  tabs: string[];
+  /** Active monitor tab; keys into `screens` to pick what renders below. */
+  value: string;
+  onChange: (tab: string) => void;
+  onClose: () => void;
+  /**
+   * The embedded screen node for each tab, keyed by tab label. The caller builds
+   * these (with `embedded` set) so this component stays a pure layout shell.
+   */
+  screens: Record<string, ReactNode>;
+}
+
+// Fills the pinned column: a fixed controls row on top and the selected screen
+// filling the remaining height below (mih:0 lets the inner ScrollArea bound).
+const ColumnLayout = Stack.withProps({
+  h: "100%",
+  gap: 0,
+});
+
+const ScreenSlot = Stack.withProps({
+  flex: 1,
+  mih: 0,
+  gap: 0,
+});
+
+/**
+ * The pinned monitoring column's content (#1616): a `MonitoringControls` tab row
+ * over the currently-selected monitor screen. Layout-only — it renders whichever
+ * embedded screen node the caller supplies for the active tab.
+ */
+export function MonitoringScreen({
+  tabs,
+  value,
+  onChange,
+  onClose,
+  screens,
+}: MonitoringScreenProps) {
+  return (
+    <ColumnLayout>
+      <MonitoringControls
+        tabs={tabs}
+        value={value}
+        onChange={onChange}
+        onClose={onClose}
+      />
+      <Divider />
+      <ScreenSlot>{screens[value]}</ScreenSlot>
+    </ColumnLayout>
+  );
+}

clients/web/src/components/groups/NetworkStreamPanel/NetworkStreamPanel.tsx

@@ -1,13 +1,5 @@
 import { useMemo } from "react";
-import {
-  Button,
-  Group,
-  Paper,
-  ScrollArea,
-  Stack,
-  Text,
-  Title,
-} from "@mantine/core";
+import { Button, Group, Paper, Stack, Text, Title } from "@mantine/core";
 import type {
   FetchRequestCategory,
   FetchRequestEntry,
@@ -18,6 +10,8 @@ import {
   SortToggle,
   type SortDirection,
 } from "../../elements/SortToggle/SortToggle";
+import { PinColumnButton } from "../../elements/PinColumnButton/PinColumnButton";
+import { EmbeddableScrollArea } from "../../elements/EmbeddableScrollArea/EmbeddableScrollArea";
 import { useScrollMemory } from "../../../hooks/useScrollMemory";
 
 export interface NetworkStreamPanelProps {
@@ -30,6 +24,10 @@ export interface NetworkStreamPanelProps {
   onSortChange: (next: SortDirection) => void;
   compact: boolean;
   onToggleCompact: () => void;
+  /** See LogStreamPanel: shows a "pin as column" button when set (#1616). */
+  onPin?: () => void;
+  /** See LogStreamPanel: fills the flex parent instead of the viewport calc. */
+  embedded?: boolean;
 }
 
 const PanelContainer = Paper.withProps({
@@ -95,6 +93,8 @@ export function NetworkStreamPanel({
   onSortChange,
   compact,
   onToggleCompact,
+  onPin,
+  embedded = false,
 }: NetworkStreamPanelProps) {
   const viewportRef = useScrollMemory("network-stream");
   const filteredEntries = useMemo(() => {
@@ -114,6 +114,7 @@ export function NetworkStreamPanel({
       <Group justify="space-between" mb="sm">
         <Title order={4}>{formatTitle(filteredEntries.length)}</Title>
         <Group gap="xs">
+          {onPin ? <PinColumnButton onPin={onPin} /> : null}
           {hasResults && (
             <ListToggle compact={compact} onToggle={onToggleCompact} />
           )}
@@ -134,12 +135,7 @@ export function NetworkStreamPanel({
       {!hasResults ? (
         <EmptyState>No network requests</EmptyState>
       ) : (
-        <ScrollArea.Autosize
-          viewportRef={viewportRef}
-          mah="calc(100vh - var(--app-shell-header-height, 0px) - 150px)"
-          type="scroll"
-          offsetScrollbars
-        >
+        <EmbeddableScrollArea embedded={embedded} viewportRef={viewportRef}>
           <Stack gap="md">
             {filteredEntries.map((entry) => (
               <NetworkEntry
@@ -149,7 +145,7 @@ export function NetworkStreamPanel({
               />
             ))}
           </Stack>
-        </ScrollArea.Autosize>
+        </EmbeddableScrollArea>
       )}
     </PanelContainer>
   );