refactor: simplify reply-threading and test helpers

src/test-utils/session-write-lock-module-mock.ts

@@ -0,0 +1,28 @@
+import { vi } from "vitest";
+import type * as SessionWriteLockModule from "../agents/session-write-lock.js";
+
+type SessionWriteLockModuleShape = typeof SessionWriteLockModule;
+
+export async function buildSessionWriteLockModuleMock(
+  importOriginal: () => Promise<SessionWriteLockModuleShape>,
+  acquireSessionWriteLock: SessionWriteLockModuleShape["acquireSessionWriteLock"],
+): Promise<SessionWriteLockModuleShape> {
+  const original = await importOriginal();
+  return {
+    ...original,
+    acquireSessionWriteLock,
+  };
+}
+
+export function resetModulesWithSessionWriteLockDoMock(
+  modulePath: string,
+  acquireSessionWriteLock: SessionWriteLockModuleShape["acquireSessionWriteLock"],
+): void {
+  vi.resetModules();
+  vi.doMock(modulePath, (importOriginal) =>
+    buildSessionWriteLockModuleMock(
+      importOriginal as () => Promise<SessionWriteLockModuleShape>,
+      acquireSessionWriteLock,
+    ),
+  );
+}