fix: avoid duplicate backlog hydration load

__tests__/stores/product-workspace/store.test.ts

@@ -257,6 +257,35 @@ describe('selection cascade', () => {
     expect(s.relations.taskIdsByStory).toEqual({})
     expect(s.loading.loadedProductId).toBeNull()
   })
+
+  it('setActiveProduct kan alleen context zetten zonder full backlog load', () => {
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith(
+        [makePbi({ id: 'p-1' })],
+        { 'p-1': [makeStory({ id: 's-1', pbi_id: 'p-1' })] },
+        { 's-1': [makeTask({ id: 't-1', story_id: 's-1' })] },
+        { id: 'prod-1', name: 'Product 1' },
+      ),
+    )
+    useProductWorkspaceStore.setState((s) => {
+      s.context.activePbiId = 'p-1'
+      s.context.activeStoryId = 's-1'
+    })
+    const fetchSpy = vi.spyOn(globalThis, 'fetch')
+
+    useProductWorkspaceStore
+      .getState()
+      .setActiveProduct(
+        { id: 'prod-1', name: 'Product 1' },
+        { load: false, preserveSelection: true },
+      )
+
+    const s = useProductWorkspaceStore.getState()
+    expect(fetchSpy).not.toHaveBeenCalled()
+    expect(s.context.activePbiId).toBe('p-1')
+    expect(s.context.activeStoryId).toBe('s-1')
+    expect(s.entities.pbisById['p-1']).toBeDefined()
+  })
 })
 
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