diff --git a/packages/app/cypress/e2e/model-architecture.cy.ts b/packages/app/cypress/e2e/model-architecture.cy.ts
index dd8d3722..30cadbb4 100644
--- a/packages/app/cypress/e2e/model-architecture.cy.ts
+++ b/packages/app/cypress/e2e/model-architecture.cy.ts
@@ -2,7 +2,10 @@ describe('Model Architecture Diagram', () => {
   before(() => {
     // Use desktop viewport to ensure all UI elements are visible
     cy.viewport(1280, 800);
-    cy.visit('/inference', {
+    // Pin to DeepSeek R1 — it has a rich architecture diagram (MoE + dense blocks)
+    // that the tests below exercise. The app's default model is DeepSeek V4 Pro,
+    // which has no architecture entry, so we select R1 explicitly via URL.
+    cy.visit('/inference?g_model=DeepSeek-R1-0528', {
       onBeforeLoad(win) {
         win.localStorage.setItem('inferencex-star-modal-dismissed', String(Date.now()));
       },
@@ -11,7 +14,7 @@ describe('Model Architecture Diagram', () => {
     cy.get('[data-testid="inference-chart-display"]').should('be.visible');
   });
 
-  it('architecture toggle renders for default model (DeepSeek R1) with MoE badges', () => {
+  it('architecture toggle renders for DeepSeek R1 with MoE badges', () => {
     cy.get('[data-testid="model-architecture-toggle"]').should('be.visible');
     cy.get('[data-testid="model-architecture-toggle"]').should(
       'contain.text',
diff --git a/packages/app/src/components/GlobalFilterContext.tsx b/packages/app/src/components/GlobalFilterContext.tsx
index d2a171ee..62ae64ff 100644
--- a/packages/app/src/components/GlobalFilterContext.tsx
+++ b/packages/app/src/components/GlobalFilterContext.tsx
@@ -141,7 +141,7 @@ export function GlobalFilterProvider({
 
   // ── Core filter state ─────────────────────────────────────────────────────
   const [selectedModel, setSelectedModel] = useState<Model>(
-    () => initialModel ?? Model.DeepSeek_R1,
+    () => initialModel ?? Model.DeepSeek_V4_Pro,
   );
 
   const [selectedSequence, setSelectedSequence] = useState<Sequence>(() => {
diff --git a/packages/app/src/lib/url-state.test.ts b/packages/app/src/lib/url-state.test.ts
index 12dd1ef4..e34b32b4 100644
--- a/packages/app/src/lib/url-state.test.ts
+++ b/packages/app/src/lib/url-state.test.ts
@@ -27,7 +27,7 @@ describe('PARAM_DEFAULTS', () => {
 
   it('has expected default for g_model', async () => {
     const { PARAM_DEFAULTS } = await import('@/lib/url-state');
-    expect(PARAM_DEFAULTS.g_model).toBe('DeepSeek-R1-0528');
+    expect(PARAM_DEFAULTS.g_model).toBe('DeepSeek-V4-Pro');
   });
 
   it('has expected default for i_seq', async () => {
@@ -164,7 +164,7 @@ describe('writeUrlParams + buildShareUrl', () => {
     const { writeUrlParams, buildShareUrl } = await import('@/lib/url-state');
 
     // write default value, should be omitted
-    writeUrlParams({ g_model: 'DeepSeek-R1-0528' });
+    writeUrlParams({ g_model: 'DeepSeek-V4-Pro' });
     await vi.advanceTimersByTimeAsync(200);
 
     const url = buildShareUrl();
@@ -375,14 +375,14 @@ describe('buildShareUrl unofficialrun handling', () => {
   });
 
   it('preserves unofficialruns alongside other in-memory share params', async () => {
-    setupWindow('?unofficialruns=111&g_model=DeepSeek-R1-0528', '/inference');
+    setupWindow('?unofficialruns=111&g_model=DeepSeek-V4-Pro', '/inference');
     const { writeUrlParams, buildShareUrl } = await import('@/lib/url-state');
 
-    writeUrlParams({ g_model: 'DeepSeek-V4-Pro' });
+    writeUrlParams({ g_model: 'DeepSeek-R1-0528' });
     await vi.advanceTimersByTimeAsync(200);
 
     const url = buildShareUrl();
-    expect(url).toContain('g_model=DeepSeek-V4-Pro');
+    expect(url).toContain('g_model=DeepSeek-R1-0528');
     expect(url).toContain('unofficialruns=111');
   });
 
diff --git a/packages/app/src/lib/url-state.ts b/packages/app/src/lib/url-state.ts
index ebaa5336..a5ba51d7 100644
--- a/packages/app/src/lib/url-state.ts
+++ b/packages/app/src/lib/url-state.ts
@@ -60,7 +60,7 @@ export type UrlStateParams = Partial<Record<UrlStateKey, string>>;
 
 /** Default values for each parameter. Params matching their default are omitted from share URLs. */
 export const PARAM_DEFAULTS: Record<UrlStateKey, string> = {
-  g_model: 'DeepSeek-R1-0528',
+  g_model: 'DeepSeek-V4-Pro',
   g_rundate: '',
   g_runid: '',
   i_seq: '8k/1k',