A workflow for cutting a 15–45 second vertical video from a demo project for YouTube Shorts, Instagram Reels, or TikTok. It offers listicle, cohost, flashcard, and glide formats with different combinations of screen recordings, captions, presenters, and text cards.

Use it to plan and create a vertical cut from an existing demo project's clips, audio, screen recordings, and Remotion app.

It treats a Short as a purpose-built edit rather than simply resizing the original demo video.

demo-shorts — Skill for Claude Code by mrieck/demoday-claude-plugin

Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo

git clone --depth 1 https://github.com/mrieck/demoday-claude-plugin

agentmods

npx agentmods add skills/mrieck/demoday-claude-plugin/demo-shorts

Made for: Claude Code.

Or install demoday, the plugin that ships this one along with the rest of its 6 skills, 1 command, 1 MCP server.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/mrieck/demoday-claude-plugin/demo-shorts/github.svg)](https://agentmods.dev/skills/mrieck/demoday-claude-plugin/demo-shorts)

Your own site

<a href="https://agentmods.dev/skills/mrieck/demoday-claude-plugin/demo-shorts"><img src="https://agentmods.dev/badge/skills/mrieck/demoday-claude-plugin/demo-shorts/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/mrieck/demoday-claude-plugin/demo-shorts"><img src="https://agentmods.dev/badge/skills/mrieck/demoday-claude-plugin/demo-shorts.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 106 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 5,964 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00106	$0.05964
Opus 5.5	$0.00042	$0.02386
Sonnet 5.5	$0.00021	$0.01193
Haiku 4.5	$0.00011	$0.00596

Measured 9d ago against content hash 59c03aafbcf5, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

demo-shorts scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/demo-shorts/SKILL.md · 401 lines

How it starts

The opening of the file, as written. The whole thing — 401 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Cutting a vertical Short

A Short is not a re-render of the demo at a different size. It is its own 15–45 second video cut from the demo project's assets. Work inside the same project directory as the main demo: the Short lives in a sibling manifest (shorts.json) that shares the project's clips, audio, cache and Remotion app.

1. Pick a style first

Everything else follows from this. Show the user the four looks and ask which their video is most like:

style	feels like	mechanics
`listicle`	"Claude just killed X, here's how" — numbered steps, the real tool running on screen, a cut every ~1.3s	beat engine: face/screen/split windows, `#N` stamps over the UI, boxed captions; hard rules (no title cards, hook cut ≤1s, no hold >2.5s)
`cohost`	screenshare with a person talking below the demo throughout	split framing, steady scene-length pacing, karaoke captions
`flashcard`	text asks, UI answers — big typographic cards alternating with full-bleed clips, no face	beat engine: insert(title)/screen windows, boxed captions
`glide`	one immersive screen recording, the camera gliding to each click	pan framing, karaoke captions

node scripts/plan.mjs --project demo/<slug> --init \
  --manifest shorts.json --from demo.json --style listicle

--style sets the format (1080×1920), presenter mode, caption style and transition policy, and records style in the manifest. --from demo.json copies product, brand, voice and presenter identity. The timeline starts empty.

Prefix every scene id with s- — both manifests share clips/ and assets/, and generated artifacts are named after scene ids.

What is reused vs regenerated

Asset	Verdict	Why
Screen captures + event logs	reused, free	Reframed (pan/split/beats) inside the 9:16 frame
Voice (designed voiceId)	reused, free	Copied by `--init --from`
Narration lines kept verbatim	reused, free	Same text + voice = cache hit
New narration lines	cents	Normal TTS pricing
B-roll	regenerated	Stills generate at 9:16; i2v inherits the aspect
Presenter clips (full scenes, split bottoms, face beats)	generated per scene	Animated to that scene's narration; billed avatar-seconds, shown in the estimate
Cards / captions / bullets / title inserts	free	Rendered, not generated
Insert stills from a `prompt`	~$0.05 each	Beats with an existing `image` are free

Read the full file on GitHub · 401 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

9d ago Changed · +3 lines 59c03aafbcf5
1mo ago Changed c410cdde16ed
1mo ago Changed · +52 lines 2a1aecbc243e
2mo ago Changed · +78 lines 06ef4c02eafa
2mo ago First seen · 268 lines · 106 tokens per session scan A 6a58873e2ad2

Subscribe to this mod's changes

demo-shorts is a skill published in the GitHub repository mrieck/demoday-claude-plugin (17 stars, last pushed 10d ago), licensed MIT. It adds 106 tokens to every session and 5,964 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Claude Code Creative and media ai-video claude-code-plugin claude-plugin demo-video-generator demo-videos

demo-shorts next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
demo-shortsmrieck/demoday-claude-plugin	Skill	17	10d ago	MIT	A	106	Claude Code
chief-revenue-officercbrock84/headcount	Skill	2.6k	19d ago	MIT	A	0	Claude Code
chief-strategy-officercbrock84/headcount	Skill	2.6k	19d ago	MIT	A	93	Claude Code
support-operationscbrock84/headcount	Skill	2.6k	19d ago	MIT	A	77	Claude Code
ai-ml-governancecbrock84/headcount	Skill	2.6k	19d ago	MIT	A	83	Claude Code
paid-advertisingcbrock84/headcount	Skill	2.6k	19d ago	MIT	A	78	Claude Code
seo-strategycbrock84/headcount	Skill	2.6k	19d ago	MIT	A	74	Claude Code