# Stop-motion video > Stop-motion video cut to music, on the beat: a motion skill for agents. By Kosta. A motion skill for Claude Code and other agents. It teaches them to make video the way a stop-motion animator would, cut to a song: one pose held on every eighth note, everything changing together, and every click landing on a drum hit. Every announcement is more fun told as a little story in motion than shown as a still. Something slides in, a line gets typed, a button gets clicked, and the next part opens right on the beat of the song. That's how I made a launch film for Steel, and this skill is what I learned making it: how to cut every move to the music, and when to let a beat go by. Every example below is built twice: once by an agent on its own, once with the skill. They all follow the metronome at the foot of the page: set its tempo, pause it on the beat, or mute it there. Drag the divider to compare, and listen for where the click lands. ## About me I’m Kosta, lead designer at [steel.dev](https://steel.dev), and I’ve been working with startups for over 3 years now. I helped them raise millions in funding, helped create compelling designs, and taught teams of designers and engineers how to apply design principles: first through systems, and now through skills and systems. I wanted to share this for free to help make startups more beautiful. ## What it covers - **Measuring the song.** Its tempo from the drum hits, where the bars, phrases and drops are, and where to cut it so every change lands on or just ahead of the sound. - **One clock.** A pose to every eighth note, beats counted on the whole video's frames, and every page starting on a bar line and changing length by whole bars. - **Poses.** Which curve to space a move with, a hand's correction, landings that don't creep, and why you never smooth the beat away. - **Hits.** Typing quicker than the beat, clicks and pops on snares, landings on downbeats. A transition may drift off the beat; a click never does. - **Skipping beats.** When to hold a pose, leave a beat empty, drop the music under a click, or cut a whole bar. - **Sound.** Clicks placed to the sample on one track, a thump tuned to the song, and a metronome for checking that never ships. - **Type.** Tracking that tightens as type grows (−1%, −2%, −3%), contrast of at least 4.5:1 at every pose, and counters in tabular figures. - **Checking.** A still for every beat, clicks measured against the song to the millisecond, and notes taken as timestamps snapped to the beat. ## When to skip a beat - **After a click that matters.** Drop the music from just before it to the next bar line, so the click is heard alone and the beat comes back with what follows. - **Under every other click.** Duck the music to 45% for 160ms, so the click's thump has room and the groove carries on. - **When an action is done.** Hold its result alone for a beat, like a tick after a copy, then move on with the next click. - **At the top of a move.** A camera that rises and comes down holds two identical poses at the top. A sweep that never stops reads as drift. - **When a note falls between beats.** Snap it to the nearest accented beat rather than splitting a pose. - **When the length has to change.** Cut a whole bar, never a single beat, or everything after it falls off the song. - **At the end.** Hold the last page about two seconds with the music under it, and end on a click of the metronome, not mid-beat. ## Poses Movement, broken into poses that keep time. What the skill does: - Any move you design, broken into poses that land on the beat. - Everything on screen changes together, on the click, so nothing drifts off the music. - Change the tempo and it keeps up. ## Typing Words that come as fast as typing does, and still keep time. What the skill does: - Any line you type, as quick as typing is, but starting and stopping on the beat. - The caret blinks with the metronome, not on a clock of its own. ## Counting A number that builds to a moment, and lands on it. What the skill does: - Any number you count up, landing on a bar line. - The figure holds still while it changes, and what's behind it cuts on the beat. ## Scene transitions Getting from one scene to the next without losing anyone on the way. What the skill does: - Any transition you design, adapted to match the BPM. - A move stops for a beat at its peak, so the eye can find where it's going. ## On-page transitions An action, and the beat the music leaves open for it. What the skill does: - Every click lands on the beat, and the music steps aside so it's heard. - What the click opens arrives on the clicks after it, whole on the bar line. ## Endings Knowing when it's over, and letting it land. What the skill does: - The video ends on the beat, after a short hold, not the moment the action is done. - Underlines, presses and holds, all timed to the music. ## Install Add it to Claude Code or any agent that supports skills: ```sh npx skills add kosta4a/stopmotion-video ``` Then tell the agent: “cut this launch video to the song, stop-motion style” Or paste this to your agent: ```text Install the Stop-motion video skill with npx skills add kosta4a/stopmotion-video, then use it on this video. Measure the soundtrack's tempo, start every scene on a bar line and put every click on a drum hit, hold each pose for one eighth note, and tell me where you'd skip a beat. Add a metronome version so I can check it, and show me one still per beat for each scene. ``` Source on GitHub: https://github.com/kosta4a/stopmotion-video --- The interactive version of this page, with every example built before and after to a metronome: https://kosta.fyi/skills/stopmotion-video