Write good demo prompts

One sentence is enough. The agent plans the steps, writes the captions and retakes on its own. A good prompt names three things.

1. The app. "the Todos app", "the Mac app in build/Notes.app". If the folder holds several schemes, name the scheme.
2. The story. One feature from start to finish: "adding a todo and checking it off", "creating a note and sharing it".
3. The length or use. "a 20-second demo", "an App Store preview", "a launch clip for X".

Film a 20-second demo of the Todos app showing how to add todos and check them off,
and save it as a replayable flow.

What makes a clean take

The agent aims for 6 to 8 steps and 15 to 30 seconds, one action per step, each with a caption of at most eight words written for the viewer ("Add a new todo", "Mark it done"). After each take end_take judges it: too few steps, too short, the keyboard left open, a step that changed nothing or a failed step make it unclean, and the agent shoots again (up to three times).

Waiting is not a problem: build time, loading and the agent's thinking are cut out of the render. Judge length by rendered_estimate_s, not by the raw recording.

Tips

• Ask for the captions you want. "Use the captions: Start in one tap, Write a note, Share it anywhere."
• Give it data. Seed content makes demos look real. Pass launch arguments for a demo mode, or photos and location to prepare_ios (demo mode).
• Pick the look. "in dark mode", "on an iPhone 17 Pro Max", "in German".
• Help it target. Elements with an .accessibilityIdentifier are found by id, which survives copy changes and translations. Without labels the agent falls back to points, which is less robust for replays.
• Keep it one story. Two features make two videos: ask for two takes and two flows.

Prompts that work

Make an App Store preview of the onboarding: open the app fresh, go through the three
onboarding pages and land on the home screen. Light mode, en_US.

Film the Mac app at ./build/Release/Notes.app: create a note called "Trip ideas",
add three bullet points and pin it. 1280x800 window.

Replay the flow add-and-check-todos in en_US, de_DE and ja_JP.