fix(web): hide resource subscription UI when server lacks subscribe capability

clients/web/src/App.tsx

@@ -2316,6 +2316,7 @@ function App() {
         onRefreshResources={onRefreshResources}
         onCompleteArgument={onCompleteArgument}
         completionsSupported={capabilities?.completions !== undefined}
+        subscriptionsSupported={capabilities?.resources?.subscribe === true}
         onTasksUiChange={setTasksUi}
         onCancelTask={(taskId) => {
           void onCancelTask(taskId);

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

@@ -145,6 +145,25 @@ export const EmptySectionCollapsed: Story = {
   },
 };
 
+// Server does not advertise resources.subscribe: the Subscriptions section is
+// omitted entirely, leaving only URIs and Templates (#1478).
+export const SubscriptionsUnsupported: Story = {
+  args: {
+    resources: sampleResources,
+    templates: sampleTemplates,
+    subscriptions: sampleSubscriptions,
+    subscriptionsSupported: false,
+  },
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    expect(canvas.queryByText(/Subscriptions/)).not.toBeInTheDocument();
+    // Only the two remaining sections render, both open → both chevrons down.
+    const transforms = chevronTransforms(canvasElement);
+    expect(transforms).toHaveLength(2);
+    for (const t of transforms) expect(t).toBe(ROTATED_DOWN);
+  },
+};
+
 // Many URIs with sparse Templates/Subscriptions: under the old equal `/ n`
 // height split, URIs scrolled while the others left their share unused. Now the
 // sections size to content inside one bounded scroll region.

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

@@ -267,6 +267,58 @@ describe("ResourceControls", () => {
     expect(onOpenSectionsChange.mock.calls[0][0]).not.toContain("templates");
   });
 
+  it("hides the Subscriptions section when subscriptionsSupported is false", () => {
+    renderWithMantine(
+      <ResourceControls {...baseProps} subscriptionsSupported={false} />,
+    );
+    expect(screen.getByText("URIs (2)")).toBeInTheDocument();
+    expect(screen.getByText("Templates (1)")).toBeInTheDocument();
+    expect(screen.queryByText(/Subscriptions/)).not.toBeInTheDocument();
+  });
+
+  it("shows the Subscriptions section by default (subscriptionsSupported omitted)", () => {
+    renderWithMantine(<ResourceControls {...baseProps} />);
+    expect(screen.getByText("Subscriptions (1)")).toBeInTheDocument();
+  });
+
+  it("reads 'Collapse all' with subscriptions hidden when the two visible sections are open", () => {
+    // allSections drops "subscriptions", so the remaining two open sections
+    // must still count as fully expanded — even if persisted openSections
+    // still carries a stale "subscriptions" entry.
+    renderWithMantine(
+      <ResourceControls
+        {...baseProps}
+        subscriptionsSupported={false}
+        compact={false}
+        openSections={["resources", "templates", "subscriptions"]}
+      />,
+    );
+    expect(
+      screen.getByRole("button", { name: "Collapse all" }),
+    ).toBeInTheDocument();
+  });
+
+  it("drops a stale 'subscriptions' entry from persisted state when subscriptions are unsupported", async () => {
+    // A "subscriptions" value persisted from a prior subscription-capable
+    // session must not be perpetually re-appended once the section is no longer
+    // rendered — toggling a visible section should emit it out of the open set.
+    const user = userEvent.setup();
+    const onOpenSectionsChange = vi.fn();
+    renderWithMantine(
+      <ResourceControls
+        {...baseProps}
+        subscriptionsSupported={false}
+        openSections={["resources", "templates", "subscriptions"]}
+        onOpenSectionsChange={onOpenSectionsChange}
+      />,
+    );
+    await user.click(screen.getByRole("button", { name: /Templates \(1\)/ }));
+    expect(onOpenSectionsChange).toHaveBeenCalledTimes(1);
+    expect(onOpenSectionsChange.mock.calls[0][0]).not.toContain(
+      "subscriptions",
+    );
+  });
+
   it("filters by resource title when title is set", async () => {
     const user = userEvent.setup();
     const resourcesWithTitle: Resource[] = [

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

@@ -21,6 +21,13 @@ export interface ResourceControlsProps {
   resources: Resource[];
   templates: ResourceTemplate[];
   subscriptions: InspectorResourceSubscription[];
+  /**
+   * Whether the connected server advertises the `resources.subscribe`
+   * capability. When false, the Subscriptions accordion section is hidden
+   * entirely. Defaults to true so the section renders unless a caller
+   * explicitly marks subscriptions unsupported.
+   */
+  subscriptionsSupported?: boolean;
   selectedUri?: string;
   selectedTemplateUri?: string;
   // Search text + accordion open-sections are controlled by the parent (App,
@@ -63,6 +70,7 @@ export function ResourceControls({
   resources,
   templates,
   subscriptions,
+  subscriptionsSupported = true,
   selectedUri,
   selectedTemplateUri,
   searchText = "",
@@ -97,15 +105,25 @@ export function ResourceControls({
       s.resource.uri.toLowerCase().includes(query),
   );
 
-  const allSections = ["resources", "templates", "subscriptions"];
+  // Subscriptions are only meaningful when the server advertises the
+  // `resources.subscribe` capability; otherwise the section is omitted
+  // entirely (no header, no panel) — see #1478.
+  const allSections = subscriptionsSupported
+    ? ["resources", "templates", "subscriptions"]
+    : ["resources", "templates"];
   // Open-sections is parent-controlled (persists across navigation). When the
   // parent hasn't set it yet (undefined), fall back to the persisted `compact`
-  // preference: empty when last left compact, all three open when expanded.
+  // preference: empty when last left compact, all sections open when expanded.
   // Per-section accordion clicks update the lifted value but don't change the
   // persisted preference.
   const openSections =
     controlledOpenSections ?? (initialCompact ? [] : [...allSections]);
-  const allExpanded = openSections.length === allSections.length;
+  // Persisted open-sections may still carry "subscriptions" from a prior
+  // subscription-capable session, so compare only the sections we actually
+  // render when deciding whether everything is expanded.
+  const allExpanded =
+    openSections.filter((section) => allSections.includes(section)).length ===
+    allSections.length;
 
   // Empty sections have a disabled control and nothing to show, so keep them
   // out of the accordion's open set — they render collapsed (chevron points
@@ -118,15 +136,20 @@ export function ResourceControls({
     subscriptions: filteredSubscriptions.length,
   };
   const visibleOpenSections = openSections.filter(
-    (section) => (sectionItemCounts[section] ?? 0) > 0,
+    (section) =>
+      allSections.includes(section) && (sectionItemCounts[section] ?? 0) > 0,
   );
   // Open-in-intent but currently empty (so excluded from the accordion's
   // `value`). Mantine derives the next open-array by toggling the clicked
   // section against the `value` we hand it, which omits these — so without
   // merging them back, toggling any populated section would silently drop an
   // empty section's intent and it wouldn't reappear once it has items again.
+  // Restricted to `allSections` so a stale "subscriptions" entry persisted from
+  // a prior subscription-capable session isn't perpetually re-appended once the
+  // section is no longer rendered — it's dropped from persisted state instead.
   const intendedButEmptySections = openSections.filter(
-    (section) => !visibleOpenSections.includes(section),
+    (section) =>
+      allSections.includes(section) && !visibleOpenSections.includes(section),
   );
   function handleOpenSectionsChange(next: string[]) {
     // Safe to append unconditionally: empty-section controls are `disabled`, so
@@ -240,28 +263,35 @@ export function ResourceControls({
           </Accordion.Panel>
         </Accordion.Item>
 
-        <Accordion.Item
-          value="subscriptions"
-          flex={sectionFlex(
-            visibleOpenSections.includes("subscriptions"),
-            filteredSubscriptions.length,
-          )}
-        >
-          <Accordion.Control disabled={filteredSubscriptions.length === 0}>
-            {formatSectionCount("Subscriptions", filteredSubscriptions.length)}
-          </Accordion.Control>
-          <Accordion.Panel>
-            <Stack gap="xs">
-              {filteredSubscriptions.map((sub) => (
-                <ResourceSubscribedItem
-                  key={sub.resource.uri}
-                  subscription={sub}
-                  onUnsubscribe={() => onUnsubscribeResource(sub.resource.uri)}
-                />
-              ))}
-            </Stack>
-          </Accordion.Panel>
-        </Accordion.Item>
+        {subscriptionsSupported && (
+          <Accordion.Item
+            value="subscriptions"
+            flex={sectionFlex(
+              visibleOpenSections.includes("subscriptions"),
+              filteredSubscriptions.length,
+            )}
+          >
+            <Accordion.Control disabled={filteredSubscriptions.length === 0}>
+              {formatSectionCount(
+                "Subscriptions",
+                filteredSubscriptions.length,
+              )}
+            </Accordion.Control>
+            <Accordion.Panel>
+              <Stack gap="xs">
+                {filteredSubscriptions.map((sub) => (
+                  <ResourceSubscribedItem
+                    key={sub.resource.uri}
+                    subscription={sub}
+                    onUnsubscribe={() =>
+                      onUnsubscribeResource(sub.resource.uri)
+                    }
+                  />
+                ))}
+              </Stack>
+            </Accordion.Panel>
+          </Accordion.Item>
+        )}
       </Accordion>
     </Stack>
   );

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

@@ -89,6 +89,25 @@ export const NotSubscribed: Story = {
   },
 };
 
+export const SubscriptionsUnsupported: Story = {
+  args: {
+    resource: {
+      name: "data.json",
+      uri: "file:///data.json",
+    },
+    contents: [
+      {
+        uri: "file:///data.json",
+        mimeType: "application/json",
+        text: JSON.stringify({ status: "active" }, null, 2),
+      },
+    ],
+    isSubscribed: false,
+    // Server does not advertise resources.subscribe — only Refresh shows.
+    subscriptionsSupported: false,
+  },
+};
+
 export const WithAnnotations: Story = {
   args: {
     resource: {

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

@@ -109,6 +109,30 @@ describe("ResourcePreviewPanel", () => {
     expect(onUnsubscribe).toHaveBeenCalledTimes(1);
   });
 
+  it("hides the Subscribe button when subscriptionsSupported is false", () => {
+    renderWithMantine(
+      <ResourcePreviewPanel {...baseProps} subscriptionsSupported={false} />,
+    );
+    expect(
+      screen.queryByRole("button", { name: "Subscribe" }),
+    ).not.toBeInTheDocument();
+    // Refresh stays available regardless of subscription support.
+    expect(screen.getByRole("button", { name: "Refresh" })).toBeInTheDocument();
+  });
+
+  it("hides the Unsubscribe button when subscriptionsSupported is false even if subscribed", () => {
+    renderWithMantine(
+      <ResourcePreviewPanel
+        {...baseProps}
+        isSubscribed
+        subscriptionsSupported={false}
+      />,
+    );
+    expect(
+      screen.queryByRole("button", { name: "Unsubscribe" }),
+    ).not.toBeInTheDocument();
+  });
+
   it("invokes onRefresh when Refresh is clicked", async () => {
     const user = userEvent.setup();
     const onRefresh = vi.fn();

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

@@ -24,6 +24,12 @@ export interface ResourcePreviewPanelProps {
   contents: (TextResourceContents | BlobResourceContents)[];
   lastUpdated?: Date;
   isSubscribed: boolean;
+  /**
+   * Whether the connected server advertises the `resources.subscribe`
+   * capability. When false, the Subscribe/Unsubscribe button is hidden.
+   * Defaults to true so the button renders unless explicitly unsupported.
+   */
+  subscriptionsSupported?: boolean;
   onRefresh: () => void;
   onSubscribe: () => void;
   onUnsubscribe: () => void;
@@ -168,6 +174,7 @@ export function ResourcePreviewPanel({
   contents,
   lastUpdated,
   isSubscribed,
+  subscriptionsSupported = true,
   onRefresh,
   onSubscribe,
   onUnsubscribe,
@@ -223,10 +230,12 @@ export function ResourcePreviewPanel({
           <Button variant="subtle" size="sm" onClick={onRefresh}>
             Refresh
           </Button>
-          <SubscribeButton
-            subscribed={isSubscribed}
-            onToggle={isSubscribed ? onUnsubscribe : onSubscribe}
-          />
+          {subscriptionsSupported && (
+            <SubscribeButton
+              subscribed={isSubscribed}
+              onToggle={isSubscribed ? onUnsubscribe : onSubscribe}
+            />
+          )}
         </ActionGroup>
       </FooterRow>
     </PanelStack>

clients/web/src/components/screens/AppsScreen/AppsScreen.tsx

@@ -63,7 +63,7 @@ export interface AppsUiState {
 
 const ScreenLayout = Flex.withProps({
   variant: "screen",
-  h: "calc(100vh - var(--app-shell-header-height, 0px))",
+  h: "calc(100dvh - var(--app-shell-header-height, 0px))",
   gap: "md",
   p: "xl",
   align: "flex-start",

clients/web/src/components/screens/HistoryScreen/HistoryScreen.tsx

@@ -39,7 +39,7 @@ export interface HistoryUiState {
 
 const ScreenLayout = Flex.withProps({
   variant: "screen",
-  h: "calc(100vh - var(--app-shell-header-height, 0px))",
+  h: "calc(100dvh - var(--app-shell-header-height, 0px))",
   gap: "md",
   p: "xl",
 });

clients/web/src/components/screens/LoggingScreen/LoggingScreen.tsx

@@ -27,7 +27,7 @@ export interface LogsUiState {
 
 const ScreenLayout = Flex.withProps({
   variant: "screen",
-  h: "calc(100vh - var(--app-shell-header-height, 0px))",
+  h: "calc(100dvh - var(--app-shell-header-height, 0px))",
   gap: "md",
   p: "xl",
 });

clients/web/src/components/screens/NetworkScreen/NetworkScreen.tsx

@@ -32,7 +32,7 @@ export interface NetworkUiState {
 
 const ScreenLayout = Flex.withProps({
   variant: "screen",
-  h: "calc(100vh - var(--app-shell-header-height, 0px))",
+  h: "calc(100dvh - var(--app-shell-header-height, 0px))",
   gap: "md",
   p: "xl",
 });

clients/web/src/components/screens/PromptsScreen/PromptsScreen.tsx

@@ -59,7 +59,7 @@ export interface PromptsUiState {
 
 const ScreenLayout = Flex.withProps({
   variant: "screen",
-  h: "calc(100vh - var(--app-shell-header-height, 0px))",
+  h: "calc(100dvh - var(--app-shell-header-height, 0px))",
   gap: "md",
   p: "xl",
 });
@@ -104,7 +104,7 @@ const EmptyState = Text.withProps({
 });
 
 const SCROLL_MAX_HEIGHT =
-  "calc(100vh - var(--app-shell-header-height, 0px) - var(--mantine-spacing-xl) * 2)";
+  "calc(100dvh - var(--app-shell-header-height, 0px) - var(--mantine-spacing-xl) * 2)";
 
 function hasArguments(prompt: Prompt): boolean {
   return !!prompt.arguments && prompt.arguments.length > 0;

clients/web/src/components/screens/ResourcesScreen/ResourcesScreen.stories.tsx

@@ -222,6 +222,21 @@ export const AllSections: Story = {
   },
 };
 
+// Server without the resources.subscribe capability: the Subscriptions
+// accordion section is omitted and no Subscribe button appears (#1478).
+export const SubscriptionsUnsupported: Story = {
+  args: {
+    resources: sampleResources,
+    templates: sampleTemplates,
+    subscriptions: sampleSubscriptions,
+    subscriptionsSupported: false,
+  },
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    expect(canvas.queryByText(/Subscriptions/)).not.toBeInTheDocument();
+  },
+};
+
 const manyResources: Resource[] = Array.from({ length: 40 }, (_, i) => ({
   name: `resource-${String(i + 1).padStart(2, "0")}.wav`,
   uri: `file:///kit/resource-${i + 1}.wav`,