feat: harden test and registry evidence

tests/mocks/contracts/envelopes.ts

@@ -0,0 +1,30 @@
+export function successEnvelope<Value>(
+  data: Value,
+  requestId = "fixture-request",
+) {
+  return Object.freeze({
+    success: true as const,
+    data: structuredClone(data),
+    meta: Object.freeze({
+      requestId,
+      traceId: "fixture-trace",
+    }),
+  });
+}
+
+export function failureEnvelope(
+  code: string,
+  details?: Readonly<Record<string, unknown>>,
+) {
+  return Object.freeze({
+    success: false as const,
+    error: Object.freeze({
+      code,
+      ...(details ? { details: structuredClone(details) } : {}),
+    }),
+    meta: Object.freeze({
+      requestId: "fixture-request",
+      traceId: "fixture-trace",
+    }),
+  });
+}