@@ -0,0 +1,9 @@
+import { randomUUID } from "node:crypto";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+
+export const screenshotPath = (namespace: string, ext: "png" | "jpeg" = "png"): string =>
+  join(tmpdir(), `pi-browser-screenshot-${namespace}-${randomUUID()}.${ext}`);
+
+export const pdfPath = (namespace: string): string =>
+  join(tmpdir(), `pi-browser-pdf-${namespace}-${randomUUID()}.pdf`);

@@ -0,0 +1,15 @@
+export type Result<T, E> =
+  | { readonly success: true; readonly data: T }
+  | { readonly success: false; readonly error: E };
+
+export const ok = <T>(data: T): Result<T, never> => ({ success: true, data });
+export const err = <E>(error: E): Result<never, E> => ({ success: false, error });
+
+export const map = <T, U, E>(r: Result<T, E>, f: (t: T) => U): Result<U, E> =>
+  r.success ? ok(f(r.data)) : r;
+
+export const andThen = <T, U, E>(r: Result<T, E>, f: (t: T) => Result<U, E>): Result<U, E> =>
+  r.success ? f(r.data) : r;
+
+export const mapErr = <T, E, F>(r: Result<T, E>, f: (e: E) => F): Result<T, F> =>
+  r.success ? r : err(f(r.error));

@@ -0,0 +1,29 @@
+export const sleep = (ms: number, signal?: AbortSignal): Promise<void> =>
+  new Promise((resolve, reject) => {
+    if (signal?.aborted) {
+      reject(new Error("aborted"));
+      return;
+    }
+    const timer = setTimeout(() => {
+      signal?.removeEventListener("abort", onAbort);
+      resolve();
+    }, ms);
+    const onAbort = (): void => {
+      clearTimeout(timer);
+      reject(new Error("aborted"));
+    };
+    signal?.addEventListener("abort", onAbort, { once: true });
+  });
+
+export type Deadline = {
+  readonly remainingMs: () => number;
+  readonly expired: () => boolean;
+};
+
+export const deadline = (totalMs: number): Deadline => {
+  const end = Date.now() + totalMs;
+  return {
+    remainingMs: () => Math.max(0, end - Date.now()),
+    expired: () => Date.now() >= end,
+  };
+};