Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/kyh/vibedgames/playtestnpx skills add kyh/vibedgames --skill playtestgit clone --depth 1 https://github.com/kyh/vibedgamesWrote 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/kyh/vibedgames/playtest)<a href="https://agentmods.dev/skills/kyh/vibedgames/playtest"><img src="https://agentmods.dev/badge/skills/kyh/vibedgames/playtest.svg" alt="Measured on agentmods" 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 | $0.00115 | $0.02566 |
| Opus 5 | $0.00057 | $0.01283 |
| Sonnet 5 | $0.00023 | $0.00513 |
| Haiku 4.5 | $0.00012 | $0.00257 |
Grade A, and why
playtest 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 yesterday.
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 — 173 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Playtest
A build that compiles proves nothing. A game that renders proves almost nothing. Playtesting proves it plays — that the loop runs, input moves the player, the objective is reachable, and nothing throws along the way.
The Tool: vg playtest
Everything here runs through one command. vg playtest is a passthrough to agent-browser, a native browser-automation CLI built for agents — vg installs it and its browser on first use, so there is nothing to add to the game's package.json. No test runner, no devDependencies, no MCP server to configure.
vg playtest open http://localhost:5173 # launch + navigate (headless by default)
vg playtest snapshot -i # interactive elements, with @eN refs
vg playtest click @e2 # act on a ref from that snapshot
vg playtest eval "window.__GAME_DIAGNOSTICS__" --json
vg playtest screenshot /tmp/frame.png
vg playtest close
A daemon persists between invocations, so one-call-per-step is cheap and the page stays open across commands.
Load the upstream skill for the general command surface
agent-browser ships its own skills and serves them from the installed binary, so the content always matches the version you actually have:
vg playtest skills get core # the general browser-automation guide — read before driving anything
vg playtest skills get core --full # + full command reference and templates
vg playtest skills get dogfood # systematic exploratory testing / bug hunts
vg playtest skills list # everything available on this version
skills get core is the source of truth for the generic surface — the snapshot-and-ref loop, sessions, waiting, forms, auth, troubleshooting. Don't re-derive it here, and don't trust a stale memory of it.
This skill covers only what upstream can't know: the game diagnostics contract, the bot playtest, canvas/WebGL determinism, --game, and the traps we hit driving real games (see below). references/cli-cheatsheet.md is the game-shaped subset of commands.
What ships with it
4 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.
- yesterday Changed · +9 lines 60637b6ca6fc
- 5d ago First seen · 164 lines · 115 tokens per session scan A 56526d441025
playtest is a skill published in the GitHub repository kyh/vibedgames (55 stars, last pushed today), licensed MIT. It adds 115 tokens to every session and 2,566 once invoked, about $0.0006 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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