fix(design): preserve command outcome certainty

tests/unit/host-api.test.ts

@@ -54,6 +54,32 @@ describe('host-api', () => {
     });
   });
 
+  it('preserves command outcome certainty from the Host API error envelope', async () => {
+    invokeIpcMock.mockResolvedValueOnce({
+      ok: true,
+      data: {
+        status: 502,
+        ok: false,
+        json: {
+          success: false,
+          code: 'design_reasoner_invalid',
+          error: 'AI 没有整理好这次想法，请再试一次',
+          commandOutcome: 'definitive_failure',
+        },
+      },
+    });
+
+    const { hostApiFetch } = await import('@/lib/host-api');
+
+    await expect(hostApiFetch('/api/works/image-workspace/workspaces/workspace-1/commands'))
+      .rejects.toMatchObject({
+        details: expect.objectContaining({
+          backendCode: 'design_reasoner_invalid',
+          commandOutcome: 'definitive_failure',
+        }),
+      });
+  });
+
   it('returns undefined for a unified 204 response', async () => {
     invokeIpcMock.mockResolvedValueOnce({
       ok: true,