test(api): harden assistant tool error handling

packages/api/src/__tests__/assistant-tools-country.test.ts

@@ -129,6 +129,25 @@ describe("assistant country tools", () => {
     });
   });
 
+  it("returns a stable error when a country cannot be resolved", async () => {
+    const ctx = createToolContext({
+      country: {
+        findUnique: vi.fn().mockResolvedValue(null),
+        findFirst: vi.fn().mockResolvedValue(null),
+      },
+    });
+
+    const result = await executeTool(
+      "get_country",
+      JSON.stringify({ identifier: "Atlantis" }),
+      ctx,
+    );
+
+    expect(JSON.parse(result.content)).toEqual({
+      error: "Country not found with the given criteria.",
+    });
+  });
+
   it("creates a country for admin users and returns an invalidation action", async () => {
     const ctx = createToolContext({
       country: {
@@ -162,6 +181,46 @@ describe("assistant country tools", () => {
     });
   });
 
+  it("returns a stable error when creating a country with a duplicate code", async () => {
+    const ctx = createToolContext({
+      country: {
+        findUnique: vi.fn().mockResolvedValue({
+          id: "country_es_existing",
+          code: "ES",
+          name: "Existing Spain",
+        }),
+      },
+    });
+
+    const result = await executeTool(
+      "create_country",
+      JSON.stringify({ code: "ES", name: "Spain", dailyWorkingHours: 8 }),
+      ctx,
+    );
+
+    expect(JSON.parse(result.content)).toEqual({
+      error: "A country with this code already exists.",
+    });
+  });
+
+  it("returns a stable error when updating a missing country", async () => {
+    const ctx = createToolContext({
+      country: {
+        findUnique: vi.fn().mockResolvedValue(null),
+      },
+    });
+
+    const result = await executeTool(
+      "update_country",
+      JSON.stringify({ id: "country_missing", data: { name: "Atlantis" } }),
+      ctx,
+    );
+
+    expect(JSON.parse(result.content)).toEqual({
+      error: "Country not found with the given criteria.",
+    });
+  });
+
   it("refuses country mutations for non-admin users", async () => {
     const ctx = createToolContext({ country: {} }, [], SystemRole.MANAGER);
 
@@ -203,4 +262,44 @@ describe("assistant country tools", () => {
       message: "Deleted metro city: Hamburg",
     });
   });
+
+  it("returns a stable error when updating a missing metro city", async () => {
+    const ctx = createToolContext({
+      metroCity: {
+        findUnique: vi.fn().mockResolvedValue(null),
+      },
+    });
+
+    const result = await executeTool(
+      "update_metro_city",
+      JSON.stringify({ id: "city_missing", data: { name: "Hamburg-Mitte" } }),
+      ctx,
+    );
+
+    expect(JSON.parse(result.content)).toEqual({
+      error: "Metro city not found with the given criteria.",
+    });
+  });
+
+  it("returns a stable error when deleting a metro city that is still assigned", async () => {
+    const ctx = createToolContext({
+      metroCity: {
+        findUnique: vi.fn().mockResolvedValue({
+          id: "city_ham",
+          name: "Hamburg",
+          _count: { resources: 3 },
+        }),
+      },
+    });
+
+    const result = await executeTool(
+      "delete_metro_city",
+      JSON.stringify({ id: "city_ham" }),
+      ctx,
+    );
+
+    expect(JSON.parse(result.content)).toEqual({
+      error: "Metro city cannot be deleted while it is still assigned to resources.",
+    });
+  });
 });