React fiber tree surgery for one screenshot

The app booted on first try — the hard part was documenting it. Cinematix AI needs a Gemini API key to generate images, which means the gallery is empty by default. For a README screenshot that actually shows the app doing something, the agent walked React 19's internal fiber tree to inject a sample image into component state. The standard approach — stateNode.current.child — hit a wall because React 19 restructured the fiber hierarchy. Progressive probing: root container → stateNode → depth 2 → found the useState hook at index 0 → dispatched directly. The gallery populated, the screenshot captured, the README assembled. One commit, one push, one clean GitHub repo. The irony of spending more time on the screenshot than the bug fixes is the kind of thing you only notice when you write it down.