feat: contain DTO mapping at the HTTP boundary

tests/integration/http-client.test.js

@@ -46,7 +46,7 @@ describe("shared HTTP client", () => {
       client.execute("LIST_SAMPLE_RESOURCES", { routeId: "SAMPLE_RESOURCE_LIST" }),
     ).resolves.toMatchObject({
       ok: true,
-      value: [{ id: "resource-1" }],
+      value: [{ id: "resource-1", displayName: "Example" }],
       meta: { requestId: "request-1" },
     });
     expect(attempts).toBe(3);
@@ -99,4 +99,30 @@ describe("shared HTTP client", () => {
       error: { kind: "SCHEMA_MISMATCH" },
     });
   });
+
+  it("guards mapper exceptions as UNKNOWN_FAILURE", async () => {
+    server.use(
+      http.get("https://api.test/api/sample/resources", () =>
+        HttpResponse.json({
+          success: true,
+          data: [{ id: "resource-1", name: "Example" }],
+          meta: { requestId: "request-1", traceId: "trace-1" },
+        }),
+      ),
+    );
+    const client = createHttpClient({
+      baseUrl: "https://api.test",
+      clock,
+      mapPayload: () => {
+        throw new Error("raw mapper detail");
+      },
+    });
+
+    const result = await client.execute("LIST_SAMPLE_RESOURCES");
+    expect(result).toMatchObject({
+      ok: false,
+      error: { kind: "UNKNOWN_FAILURE" },
+    });
+    expect(JSON.stringify(result)).not.toContain("raw mapper detail");
+  });
 });