proofsheet-core

The engine behind proofsheet: exact-pixel App Store and Google Play screenshots from a real browser, deterministic and local-first.

This crate is the library. For the command-line tool, install proofsheet.

[dependencies]
proofsheet-core = "0.1"

use proofsheet_core::{device, find_browser, progress::Silent, run,
                      Determinism, RunOptions, Stability, Store};

let presets = device::builtin();
let report = run(&RunOptions {
    url: "http://localhost:5173".into(),
    devices: device::for_store(&presets, Store::Apple),
    out_dir: "./shots".into(),
    determinism: Determinism { seed: 42, ..Default::default() },
    stability: Stability::default(),
    browser: find_browser(None)?,
    fail_fast: false,
}, &mut Silent)?;

// `ok`, not `failed == 0` -- the latter is also true when nothing was captured.
assert!(report.ok, "{} off-size, {} failed", report.off_size, report.failed);

What it does that a screenshot script doesn't

Exact pixels by construction. A preset stores the output size the store requires and derives the viewport as output / scale. A preset whose output doesn't divide evenly is rejected at parse time, so "the size we emit is a size the store accepts" is structural rather than arithmetic someone got right.

Deterministic runs. A preamble injected before any page script seeds Math.random, freezes Date.now and performance.now, drives requestAnimationFrame on a fixed virtual step, and pins locale and timezone through CDP. Same seed, byte-identical PNGs.

Wrong-layout detection. A page can be captured at exactly the right pixel count and still show a desktop layout scaled into a phone frame. Every Capture carries an Environment recording what the page actually did — assert on viewport_honoured, not just the dimensions.

No async runtime, no browser automation framework, no HTTP client. The WebSocket and CDP client are hand-rolled std.

Documentation

Full docs, device tables and examples: github.com/interchained/proofsheet

License

BUSL-1.1, converting to MIT on 2030-08-22. Property made in part by Interchained LLC Labs.