Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add popmechanic/VibesOS/plugin install VibesOSWrote 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/popmechanic/vibesos/riff)<a href="https://agentmods.dev/skills/popmechanic/vibesos/riff"><img src="https://agentmods.dev/badge/skills/popmechanic/vibesos/riff/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/popmechanic/vibesos/riff"><img src="https://agentmods.dev/badge/skills/popmechanic/vibesos/riff.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 | $0.00062 | $0.02322 |
| Opus 5 | $0.00031 | $0.01161 |
| Sonnet 5 | $0.00012 | $0.00464 |
| Haiku 4.5 | $0.00006 | $0.00232 |
Grade A, and why
riff 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 10d 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 — 214 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Plan mode: If you are planning work, this entire skill is ONE plan step: "Invoke /vibes:riff". Do not decompose the steps below into separate plan tasks.
Display this ASCII art immediately when starting:
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Vibes Riff Generator
Generate multiple app variations in parallel. Each riff is a different INTERPRETATION - different ideas, not just styling.
Terminal or Editor UI?
Detect whether you're running in a terminal (Claude Code CLI) or an editor (Cursor, Windsurf, VS Code with Copilot). Terminal agents use AskUserQuestion for all input. Editor agents present requirements as a checklist comment, wait for user edits, then proceed. See the vibes skill for the full detection and interaction pattern.
Workflow
Step 1: Gather ALL Requirements Upfront
Use AskUserQuestion to collect all config at once.
Question 1: "What kind of app do you want to explore? (broad/loose is fine)"
Header: "Theme"
Options: User enters via "Other"
Question 2: "Describe the visual style - colors, mood, aesthetic"
Header: "Visual"
Options: ["Warm sunset tones", "Clean minimal white", "Neon cyberpunk", "Other (describe)"]
Question 3: "How many variations should I generate?"
Header: "Count"
Options: ["3 (recommended)", "5", "7", "10"]
After receiving all answers, proceed immediately to Step 2 - no more questions.
Note: If the frontend-design skill is available, use it for enhanced visual design quality.
Step 2: Create Riff Directories
mkdir -p riff-1 riff-2 riff-3 ...
Step 3: Generate Riffs in Parallel
Use the bundled script to generate riffs in parallel. Each script instance calls claude -p (uses subscription tokens) and writes directly to disk.
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 10d ago First seen · 214 lines · 62 tokens per session scan A 4320e67790b3
riff is a skill published in the GitHub repository popmechanic/VibesOS (133 stars, last pushed 1mo ago), licensed MIT. It adds 62 tokens to every session and 2,322 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 2026-08-30.
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