Sonnet 5.5 is the same quality as Opus 5.5, but cheaper. Icreated me a 30-second motion graphics about Reddit. Everything is generated.

gets you when the thing you're vibe coding isn't an app. So I gave Claude Code (Sonnet 5.5) this, in an empty folder:

>make a dynamic 30-second motion graphics video about Reddit that shows what an incredible motion designer you are. and not too fast, people should actually understand what the video is about.

**What it actually is:** no After Effects, no stock footage, no video model. It's plain JS drawing on a canvas in headless Chrome, one frame at a time, piped into ffmpeg. The music is synthesized in numpy. One timing file drives both the visuals and the audio, so every slam on screen has a hit in the sound.

**What worked (stuff you can steal):**

* **Make it look at its own output.** After every change it rendered a contact sheet of frames and read the image. That's how it caught things like a word that never appeared because of a math bug, and text running off the screen. Without that loop I'd have been the one finding all of that.
* **One source of truth for timing.** A single `sync.js` for beats and impacts. Change a number and the visuals and the sound move together.
* **Parallel agents, one file each.** For the 30 s version it spun up 5 builders (one per shot), then 5 independent reviewers who weren't allowed to edit, then fixers. The reviewers found real stuff, including a bug that would have crashed the final render at one specific frame.
* **Steer in plain English.**