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.
git clone --depth 1 https://github.com/mrieck/demoday-claude-pluginnpx agentmods add skills/mrieck/demoday-claude-plugin/demo-assemblyWrote 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.
[](https://agentmods.dev/skills/mrieck/demoday-claude-plugin/demo-assembly)<a href="https://agentmods.dev/skills/mrieck/demoday-claude-plugin/demo-assembly"><img src="https://agentmods.dev/badge/skills/mrieck/demoday-claude-plugin/demo-assembly/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.
<a href="https://agentmods.dev/skills/mrieck/demoday-claude-plugin/demo-assembly"><img src="https://agentmods.dev/badge/skills/mrieck/demoday-claude-plugin/demo-assembly.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00064 | $0.02167 |
| Opus 5 | $0.00032 | $0.01084 |
| Sonnet 5 | $0.00013 | $0.00433 |
| Haiku 4.5 | $0.00006 | $0.00217 |
Grade A, and why
demo-assembly 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 6d 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.
How it starts
The opening of the file, as written. The whole thing — 175 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Assembling the video
Remotion owns the finished timeline. ffmpeg only prepares inputs (trimming, cropping, normalising). That split is what makes transitions, captions and overlays on top of the footage possible in a single deterministic render.
node scripts/render/render.mjs --project demo/<slug> # render
node scripts/render/render.mjs --project demo/<slug> --studio # open the editor
(demo/<slug> is the video's project folder, e.g. demo/project-overview —
one per video.)
The first run copies remotion-template/ into demo/<slug>/remotion/ and installs it.
It is never overwritten afterwards, so any edits the user makes there survive.
How props reach the renderer
build-props.mjs turns demo.json into props and does three things the renderer
should not have to:
- Verifies every artifact exists. A missing clip becomes a clear error rather than a black rectangle.
- Inlines the event log and word timings so components never touch the disk.
- Reconciles durations. Generated video comes back at whatever length the model chose; if a clip is shorter than its scene, the scene is trimmed to the clip rather than freezing on the last frame.
Media resolves through --public-dir <project>, so staticFile("clips/x.mp4")
points straight at the pipeline's output. Nothing is copied.
What the renderer does with the event log
DemoClip reads the capture's event log and eases the frame toward each click
just before it lands, holding briefly, then easing out. This is the single biggest
difference between "screen recording" and "product video" — it leads the viewer's
eye across a 1920px UI.
Zoom is deliberately gentle (1.18×). The footage is already rasterised, so pushing
harder makes text mushy and reads as a jump cut. Disable per scene with
"zoomToClick": false.
Callouts with "anchor": "lastClick" place themselves next to the most recent
click — where the viewer is already looking.
Audio
- Narration is laid out on an absolute timeline, not inside scenes, because transitions overlap scenes and two overlapping voices are instantly audible.
- Presenter clips are muted; the original narration track plays instead. The avatar's baked-in audio is a re-encode of the same thing.
- A music bed ducks under narration automatically (
music.duckDb, default −14 dB). Without ducking it sounds like a stock template.
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.
- 6d ago Changed · +40 lines 4e6cd9fc3d57
- 10d ago First seen · 135 lines · 64 tokens per session scan A 8de3c72aa203
demo-assembly is a skill published in the GitHub repository mrieck/demoday-claude-plugin (2 stars, last pushed 6d ago), licensed MIT. It adds 64 tokens to every session and 2,167 once invoked, about $0.0003 per session on Opus 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.
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