Files
sanderling/pkg/spec
pj d987526e47 Merge origin/master into llm-recording-and-analysis
Brings in #73, which landed web fact-parity work overlapping this branch:
selector-tagged ax handles, aria-disabled in `enabled`, shadow-DOM traversal
and a `scrollable`/`editable` dump, plus a third folio property and two new
testTags on HomeScreen.

Six files conflicted. The option-carrying ones took the union of both sides'
fields, so `--label-source` and `--exit-on-violation` both reach the pipeline.
In web-runtime.ts both sides changed how an element is described: master gave
`elementHandle` a selector to tag handles with, this branch gave it raw
attribute names and a field hint. Both survive, and `enabled` now answers
through master's isEnabled while `editable` stays.

Claude-Session: https://claude.ai/code/session_01A5KmftdEJ49A9z5mF5ESrX
2026-08-15 13:28:11 +05:30
..

@sanderling/spec

TypeScript spec API for sanderling, a property-based UI fuzzer for mobile and web apps.

Spec authors write properties (what the app must always or eventually do), extractors (structured state from the UI), and action generators (what sanderling is allowed to do). The sanderling CLI evaluates the spec in a loop against a running app.

Install

npm install --save-dev @sanderling/spec

Usage

import { extract, always, eventually, actions, weighted, taps, swipes, InputText, Tap } from "@sanderling/spec";

const loggedIn = extract((s) => !!s.ax.find("id:home-tab-bar"));
const balance = extract<number>((s) => (s.snapshots.balance as number) ?? 0);
const emailField = extract((s) => s.ax.find("id:email-field"));
const submitButton = extract((s) => s.ax.find("id:sign-in-button"));

export const properties = {
  balanceNeverNegative: always(() => balance.current >= 0),
  loginSucceeds: eventually(() => loggedIn.current).within(30, "seconds"),
};

const doLogin = actions(() => {
  if (loggedIn.current) return [];
  const email = emailField.current;
  const submit = submitButton.current;
  if (!email || !submit) return [];
  return [InputText({ into: email, text: "[email protected]" }), Tap({ on: submit })];
});

export const actionsRoot = weighted(
  [50, doLogin],
  [10, taps],
  [2,  swipes],
);

Setup actions

Some action generators are not fuzz targets but preconditions: they drive the app from a fresh state into the surface you actually want to fuzz (login, onboarding, permission grants, seed data). Export them as setup instead of mixing them into actionsRoot. The runner tries setup first; if it yields no action, it falls through to actionsRoot. State regressing back across the precondition (e.g. logout under fuzz) automatically re-engages setup.

const login = actions(() => {
  if (loggedIn.current) return [];
  return [InputText({ into: emailField.current!, text: "[email protected]" }), Tap({ on: submitButton.current! })];
});

export const setup = login;
export const actionsRoot = weighted([60, browse], [40, edit]);

(globalThis as { setup?: unknown }).setup = setup;

Setup is just an ActionGenerator; compose with actions, weighted, or whenRoute exactly like the main pool.

Works identically across Android, iOS, and web targets.