diff --git a/apps/web/src/components/NewProjectPanel.tsx b/apps/web/src/components/NewProjectPanel.tsx
index e1f9f387f..f00bfac2c 100644
--- a/apps/web/src/components/NewProjectPanel.tsx
+++ b/apps/web/src/components/NewProjectPanel.tsx
@@ -75,6 +75,28 @@ const TAB_LABEL_KEYS: Record<CreateTab, keyof Dict> = {
   other: 'newproj.tabOther',
 };
 
+export function defaultDesignSystemSelection(
+  defaultDesignSystemId: string | null,
+  designSystems: DesignSystemSummary[],
+): string[] {
+  if (!defaultDesignSystemId) return [];
+  return designSystems.some((d) => d.id === defaultDesignSystemId)
+    ? [defaultDesignSystemId]
+    : [];
+}
+
+export function buildDesignSystemCreateSelection(
+  showDesignSystemPicker: boolean,
+  selectedIds: string[],
+): { primary: string | null; inspirations: string[] } {
+  return showDesignSystemPicker
+    ? {
+        primary: selectedIds[0] ?? null,
+        inspirations: selectedIds.slice(1),
+      }
+    : { primary: null, inspirations: [] };
+}
+
 export function NewProjectPanel({
   skills,
   designSystems,
@@ -99,7 +121,14 @@ export function NewProjectPanel({
   // Design-system selection is now an *array* internally so the same
   // component can drive both single-select and multi-select modes without
   // duplicating state. Single-select coerces to length 0/1.
-  const [selectedDsIds, setSelectedDsIds] = useState<string[]>([]);
+  const initialDefaultDsSelection = useMemo(
+    () => defaultDesignSystemSelection(defaultDesignSystemId, designSystems),
+    [defaultDesignSystemId, designSystems],
+  );
+  const [selectedDsIds, setSelectedDsIds] = useState<string[]>(
+    () => initialDefaultDsSelection,
+  );
+  const [dsSelectionTouched, setDsSelectionTouched] = useState(false);
   const [dsMulti, setDsMulti] = useState(false);
 
   // Per-tab metadata. Tracked independently so switching tabs preserves
@@ -166,6 +195,11 @@ export function NewProjectPanel({
   const showDesignSystemPicker =
     tabSupportsDesignSystem && !tabDefaultSkillForcesNoDs;
 
+  useEffect(() => {
+    if (dsSelectionTouched) return;
+    setSelectedDsIds(initialDefaultDsSelection);
+  }, [dsSelectionTouched, initialDefaultDsSelection]);
+
   // When entering the template tab, snap to the first user-saved template
   // if there is one (and we don't already have a valid pick). The template
   // tab no longer offers a built-in fallback — the entire point is to
@@ -242,6 +276,11 @@ export function NewProjectPanel({
     });
   }
 
+  function handleDesignSystemChange(ids: string[]) {
+    setDsSelectionTouched(true);
+    setSelectedDsIds(ids);
+  }
+
   useEffect(() => {
     const el = tabsRef.current;
     if (!el) return;
@@ -269,8 +308,8 @@ export function NewProjectPanel({
     // and inspiration ids to empty there so the New Project panel can't
     // accidentally bind a stale DS that the user can no longer see in the
     // form (the picker is hidden for image/video/audio).
-    const primaryDs = showDesignSystemPicker ? selectedDsIds[0] ?? null : null;
-    const inspirations = showDesignSystemPicker ? selectedDsIds.slice(1) : [];
+    const { primary: primaryDs, inspirations } =
+      buildDesignSystemCreateSelection(showDesignSystemPicker, selectedDsIds);
     const promptTemplatePick =
       tab === 'image'
         ? imagePromptTemplate
@@ -379,7 +418,7 @@ export function NewProjectPanel({
             selectedIds={selectedDsIds}
             multi={dsMulti}
             onChangeMulti={setDsMulti}
-            onChange={setSelectedDsIds}
+            onChange={handleDesignSystemChange}
             loading={loading}
           />
         ) : null}
diff --git a/apps/web/tests/components/NewProjectPanel.test.tsx b/apps/web/tests/components/NewProjectPanel.test.tsx
new file mode 100644
index 000000000..50122a67f
--- /dev/null
+++ b/apps/web/tests/components/NewProjectPanel.test.tsx
@@ -0,0 +1,72 @@
+import { renderToStaticMarkup } from 'react-dom/server';
+import { describe, expect, it, vi } from 'vitest';
+
+import {
+  buildDesignSystemCreateSelection,
+  defaultDesignSystemSelection,
+  NewProjectPanel,
+} from '../../src/components/NewProjectPanel';
+import type { DesignSystemSummary, SkillSummary } from '../../src/types';
+
+const skills: SkillSummary[] = [
+  {
+    id: 'prototype-skill',
+    name: 'Prototype',
+    description: 'Build prototypes',
+    mode: 'prototype',
+    surface: 'web',
+    previewType: 'html',
+    designSystemRequired: false,
+    defaultFor: ['prototype'],
+    triggers: [],
+    upstream: null,
+    hasBody: true,
+    examplePrompt: 'Build a prototype.',
+  },
+];
+
+const designSystems: DesignSystemSummary[] = [
+  {
+    id: 'clay',
+    title: 'Clay',
+    summary: 'Friendly tactile product UI.',
+    category: 'Product',
+    swatches: ['#f4efe7', '#25211d'],
+  },
+];
+
+describe('NewProjectPanel design system defaults', () => {
+  it('uses the configured default design system when it exists in the catalog', () => {
+    expect(defaultDesignSystemSelection('clay', designSystems)).toEqual(['clay']);
+    expect(defaultDesignSystemSelection('missing', designSystems)).toEqual([]);
+    expect(defaultDesignSystemSelection(null, designSystems)).toEqual([]);
+  });
+
+  it('shows the configured default design system as the active project selection', () => {
+    const markup = renderToStaticMarkup(
+      <NewProjectPanel
+        skills={skills}
+        designSystems={designSystems}
+        defaultDesignSystemId="clay"
+        templates={[]}
+        promptTemplates={[]}
+        onCreate={vi.fn()}
+      />,
+    );
+
+    expect(markup).toContain('Clay');
+    expect(markup).toContain('Default');
+    expect(markup).not.toContain('Freeform');
+  });
+
+  it('keeps media project creation from inheriting a hidden design system pick', () => {
+    expect(buildDesignSystemCreateSelection(true, ['clay', 'bmw'])).toEqual({
+      primary: 'clay',
+      inspirations: ['bmw'],
+    });
+    expect(buildDesignSystemCreateSelection(false, ['clay', 'bmw'])).toEqual({
+      primary: null,
+      inspirations: [],
+    });
+  });
+});