diff --git a/calm-plugins/vscode/src/extension/services/hub-status-bar.test.ts b/calm-plugins/vscode/src/extension/services/hub-status-bar.test.ts
index 56fb8bddd1..bf217374be 100644
--- a/calm-plugins/vscode/src/extension/services/hub-status-bar.test.ts
+++ b/calm-plugins/vscode/src/extension/services/hub-status-bar.test.ts
@@ -96,6 +96,15 @@ describe('HubStatusBar', () => {
             expect(mockItem.tooltip).toContain('○ ns2');
             expect(mockItem.tooltip).toContain('✓ ns3');
         });
+
+        it('marks every namespace as selected when the selection is empty', () => {
+            statusBar.setState('connected', 2);
+            statusBar.setAvailableAndSelected(['alpha', 'beta'], []);
+            expect(mockItem.text).toBe('$(cloud) CALM Hub (2)');
+            expect(mockItem.tooltip).toContain('Namespaces (2 selected / 2 available)');
+            expect(mockItem.tooltip).toContain('✓ alpha');
+            expect(mockItem.tooltip).toContain('✓ beta');
+        });
     });
 
     describe('dispose', () => {
diff --git a/calm-plugins/vscode/src/extension/services/hub-status-bar.ts b/calm-plugins/vscode/src/extension/services/hub-status-bar.ts
index afaf492aab..2ad8df32c7 100644
--- a/calm-plugins/vscode/src/extension/services/hub-status-bar.ts
+++ b/calm-plugins/vscode/src/extension/services/hub-status-bar.ts
@@ -1,4 +1,5 @@
 import * as vscode from 'vscode';
+import { resolveSelectedNamespaces } from './namespace-selection';
 
 export type ConnectionState = 'disconnected' | 'connecting' | 'connected' | 'error';
 
@@ -64,11 +65,13 @@ export class HubStatusBar {
                 const countLabel = selCount > 0 ? `${selCount}/${availCount}` : `${availCount}`;
                 this.statusBarItem.text = `$(cloud) CALM Hub (${countLabel})`;
 
+                // An empty selection means "all namespaces", so the tooltip resolves it (#3493).
+                const selected = resolveSelectedNamespaces(this.availableNamespaces, this.selectedNamespaces);
                 const nsList = this.availableNamespaces.map((ns) =>
-                    this.selectedNamespaces.includes(ns) ? `  ✓ ${ns}` : `  ○ ${ns}`
+                    selected.includes(ns) ? `  ✓ ${ns}` : `  ○ ${ns}`
                 ).join('\n');
                 this.statusBarItem.tooltip = (this.hubUrl ? `${this.hubUrl}\n\n` : '') +
-                    `Namespaces (${selCount} selected / ${availCount} available):\n` +
+                    `Namespaces (${selected.length} selected / ${availCount} available):\n` +
                     nsList +
                     '\n\nClick to manage';
                 this.statusBarItem.backgroundColor = undefined;
diff --git a/calm-plugins/vscode/src/extension/services/namespace-selection.test.ts b/calm-plugins/vscode/src/extension/services/namespace-selection.test.ts
new file mode 100644
index 0000000000..79ab454d13
--- /dev/null
+++ b/calm-plugins/vscode/src/extension/services/namespace-selection.test.ts
@@ -0,0 +1,27 @@
+import { describe, it, expect } from 'vitest';
+import { resolveSelectedNamespaces } from './namespace-selection';
+
+describe('resolveSelectedNamespaces', () => {
+    const available = ['alpha', 'beta', 'gamma'];
+
+    it('treats an empty selection as "all namespaces"', () => {
+        expect(resolveSelectedNamespaces(available, [])).toEqual(available);
+    });
+
+    it('treats an unset selection as "all namespaces"', () => {
+        expect(resolveSelectedNamespaces(available, undefined)).toEqual(available);
+        expect(resolveSelectedNamespaces(available, null)).toEqual(available);
+    });
+
+    it('keeps only the selected namespaces', () => {
+        expect(resolveSelectedNamespaces(available, ['gamma', 'alpha'])).toEqual(['alpha', 'gamma']);
+    });
+
+    it('drops names that the hub no longer lists', () => {
+        expect(resolveSelectedNamespaces(available, ['alpha', 'gone'])).toEqual(['alpha']);
+    });
+
+    it('returns nothing when the hub lists no namespaces', () => {
+        expect(resolveSelectedNamespaces([], [])).toEqual([]);
+    });
+});
diff --git a/calm-plugins/vscode/src/extension/services/namespace-selection.ts b/calm-plugins/vscode/src/extension/services/namespace-selection.ts
new file mode 100644
index 0000000000..cf1d6e0128
--- /dev/null
+++ b/calm-plugins/vscode/src/extension/services/namespace-selection.ts
@@ -0,0 +1,17 @@
+/**
+ * Resolve the `calm.hub.selectedNamespaces` setting against the namespaces the
+ * Hub lists.
+ *
+ * CALM Hub has no namespace selection of its own: the filter is this plugin's
+ * setting. VS Code reports an unset string array as `[]`, so `undefined`, `null`
+ * and `[]` all mean "every namespace".
+ */
+export function resolveSelectedNamespaces(
+    available: readonly string[],
+    selection: readonly string[] | null | undefined
+): string[] {
+    if (!selection || selection.length === 0) {
+        return [...available];
+    }
+    return available.filter((namespace) => selection.includes(namespace));
+}
diff --git a/calm-plugins/vscode/src/extension/webview/canvas-panel.ts b/calm-plugins/vscode/src/extension/webview/canvas-panel.ts
index b64d8af6e7..deb60315e9 100644
--- a/calm-plugins/vscode/src/extension/webview/canvas-panel.ts
+++ b/calm-plugins/vscode/src/extension/webview/canvas-panel.ts
@@ -8,6 +8,7 @@ import { DiagramExportService } from '../services/diagram-export-service';
 import { HubClient, describeHubError } from '../services/hub-client';
 import { HubAssetService, type HubNamespace } from '../services/hub-asset-service';
 import { ControlAssetService, LOCAL_DOMAIN } from '../services/control-asset-service';
+import { resolveSelectedNamespaces } from '../services/namespace-selection';
 import { ShaCacheService } from '../services/sha-cache-service';
 import { SvgImportService } from '../services/svg-import';
 import {
@@ -346,10 +347,7 @@ export class CanvasPanel {
 
         const allNs = this.hubAssetService?.getNamespaces().map(ns => ns.name) ?? [];
         const userSelection = vscode.workspace.getConfiguration('calm.hub').get<string[]>('selectedNamespaces');
-        // VS Code defaults unset arrays to []. Treat null/undefined/[] as "show all".
-        const selectedNs = (userSelection && userSelection.length > 0)
-            ? allNs.filter(ns => userSelection.includes(ns))
-            : allNs;
+        const selectedNs = resolveSelectedNamespaces(allNs, userSelection);
         const hubBlocks = this.hubAssetService?.getAllStandardNodes(selectedNs) ?? [];
         const hubPatterns = this.hubAssetService?.getAllPatterns(selectedNs) ?? [];