fix: close internal semantic review gaps

backend/test/routes-workspaces.test.ts

@@ -238,7 +238,7 @@ test("validates a canonical workspace and runs the injected installation diagnos
   expect(diagnose).not.toHaveBeenCalled();
 });
 
-test("runs the injected installation diagnostic for a migration-required v2 workspace when legacy bindings resolve", async () => {
+test("rejects a migration-required v2 workspace before resolving semantic diagnostics", async () => {
   const diagnose = vi.fn(async () => ({
     activatable: false,
     diagnostics: [{ level: "error" as const, code: "binding_missing" as const, field: "THT_WS_PSD_CLINICAL_VECTOR_BASE_URL", message: "Installation binding is missing or invalid." }],
@@ -257,13 +257,12 @@ test("runs the injected installation diagnostic for a migration-required v2 work
   try {
     const testResult = await app.inject({ method: "POST", url: "/workspaces/psd-clinical/test", payload: {} });
 
-    expect(testResult.statusCode).toBe(200);
-    expect(testResult.json()).toMatchObject({ activatable: false, diagnostics: [{ code: "binding_missing" }] });
-    expect(diagnose).toHaveBeenCalledWith(workspaceV2, expect.objectContaining({
-      dwh: expect.objectContaining({ transport: "rest_api", missing: [] }),
-      vector: expect.objectContaining({ transport: "rest_api", missing: [] }),
-      embedding: expect.objectContaining({ transport: "rest_api", missing: [] }),
-    }), { writeProbe: false });
+    expect(testResult.statusCode).toBe(400);
+    expect(testResult.json()).toEqual({
+      code: "workspace_not_activatable",
+      message: "Workspace cannot be activated on this installation.",
+    });
+    expect(diagnose).not.toHaveBeenCalled();
   } finally {
     process.env = originalEnv;
   }