Screenshot Scene Protocol

simshot launches your app with a fixed argument set. Your app owns the scene names and what they do — simshot only passes them through.

Argument	Meaning
--ui-testing	Tell the app this is an automated session (skip onboarding etc.).
--screenshot-scene <scene>	Navigate to the named scene on launch.
--screenshot-strokes <N>	Perform N interactions (e.g. draw N strokes). Optional.
--screenshot-scroll-bottom	Scroll the scene to the bottom before capturing. Optional.

In addition, simshot always passes -AppleLanguages (lang) and -AppleLocale locale so the app renders in the requested language (no app-side implementation needed).

This protocol is a public contract. Changing it requires updating this page, the README (en/ja/ko), and Sources/SimshotCore/ShotSpec.swift.

App-side implementation (SwiftUI)

A complete sample is in examples/DemoSceneHandler.swift. The gist: interpret the launch arguments in the root view's onAppear and navigate to the matching scene:

import SwiftUI

struct HomeView: View {
    @State private var path: [Character] = []
    @State private var showSettings = false

    var body: some View {
        NavigationStack(path: $path) {
            content
                .onAppear {
                    #if DEBUG
                    handleScreenshotScene()
                    #endif
                }
        }
        .sheet(isPresented: $showSettings) {
            SettingsView()
        }
    }

    #if DEBUG
    /// Screenshot-capture support: interpret simshot's launch arguments.
    private func handleScreenshotScene() {
        let args = ProcessInfo.processInfo.arguments
        guard let index = args.firstIndex(of: "--screenshot-scene"),
              index + 1 < args.count else { return }
        let scene = args[index + 1]
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.3) {
            switch scene {
            case "detail":
                if let first = characters.first {
                    path = [first]
                }
            case "settings":
                showSettings = true
            default:
                break // "home" is the default screen
            }
        }
    }
    #endif
}

Because the handler lives behind #if DEBUG, it never ships in a release build.

Launch-argument reference

The exact arguments simshot passes to the app on every launch:

Argument	Present when
--ui-testing	always (unless --no-ui-testing)
--screenshot-scene <scene>	always
--screenshot-strokes <N>	strokes set in shots.json
--screenshot-scroll-bottom	scrollBottom: true in shots.json
-AppleLanguages (lang)	always
-AppleLocale <locale>	always