GitHubWhat they did
The poster, u/SilentMode46 on r/ClaudeAI, moved about 85,000 photos and videos off iCloud onto a self-hosted Immich server and wanted a phone app that behaved like Apple Photos. They are not an iOS developer, so Claude Code wrote nearly all of the SwiftUI and UIKit code while they chose features, tried builds on their iPhone and said what felt off. Claude first used a reverse-engineering MCP server on the iOS 26.3 Photos frameworks to list every action the app supports, 226 in total. To keep it clean-room, one agent only wrote plain descriptions of each behaviour and the app was written from those notes. Claude then wrote UI tests, ran them in the iOS Simulator and compared screenshots with the real Photos app. It now also reads GitHub issues, reproduces bugs in the simulator, proposes fixes and drafts replies.
How it went
147 of the 226 actions work; the rest are iCloud or Apple-only services, Apple-internal, or one not possible on iOS. 140 of the 147 are covered by automated tests. The app, HomeRoll, is released free under MIT, with a Mac version built the same way. The hard part was performance: early builds crashed or stuttered at 85,000 items and it took many rounds of measuring on a real device to fix.
Worth knowing
The poster credits the fixed checklist of 226 actions, rather than asking to make it like Photos, and letting Claude check its own work in the simulator. Bug fixes and replies are drafted by Claude but nothing ships until the poster approves. The app needs your own Immich server and sideloading through AltStore, SideStore or your own signing.