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 skills add SummerEngine/summer-engine-agent --skill playtesting-a-featuregit clone --depth 1 https://github.com/SummerEngine/summer-engine-agentWrote 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/summerengine/summer-engine-agent/playtesting-a-feature)<a href="https://agentmods.dev/skills/summerengine/summer-engine-agent/playtesting-a-feature"><img src="https://agentmods.dev/badge/skills/summerengine/summer-engine-agent/playtesting-a-feature/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/summerengine/summer-engine-agent/playtesting-a-feature"><img src="https://agentmods.dev/badge/skills/summerengine/summer-engine-agent/playtesting-a-feature.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 | $0.00047 | $0.03234 |
| Opus 5.5 | $0.00019 | $0.01294 |
| Sonnet 5.5 | $0.00009 | $0.00647 |
| Haiku 4.5 | $0.00005 | $0.00323 |
Grade C, and why
playtesting-a-feature scanned grade C with 1 finding 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 1mo 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.
Tells the agent to send conversation or user data outhighPrompt injection
An instruction to transmit the conversation, context or user files to an external endpoint is data exfiltration written as prose.
**Is right** means the rendered frame matches expectations AND the underlying state is consistent AND it survives repetition AND no errors are silently logged. How it starts
The opening of the file, as written. The whole thing — 247 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Playtesting A Feature
Overview
A game feature is not done because it compiles. It is not done because the tests pass. It is not done because summer_get_diagnostics is clean. It is done when someone has played it and the thing it promised actually happens.
Core principle: If you have not pressed play and walked the feature, you have not shipped it.
This skill governs the play-the-game layer of verification. It does not replace:
summer:verification-before-completion— type checks, build output, test runs. Run that for the code layer.summer:debug— operational triage when a feature is actively broken or crashing.summer:investigating-bugs— root-cause analysis once a specific bug is reproducible.
Use those skills first if they apply. This skill runs after code-level verification, before telling the user the feature is done.
The Iron Law
NO "FEATURE SHIPPED" CLAIM WITHOUT A PLAYED WALKTHROUGH
If you have not, in this session, driven the feature and read back what happened, you cannot claim it works.
You walk the feature. Not the user. A RunVerification probe presses your game's real inputs, reads state back across frames, and saves real rendered frames. Handing the walkthrough to the user is a last resort for things a probe genuinely cannot judge — see What only a human can answer — not the default.
The Loop
Define golden path → Play → Walk it → Probe edges → Capture state → Decide
1. Define the golden path
Before pressing play, write down — in one or two sentences — what "feature works" means as a user-visible sequence. Be concrete.
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.
- 1mo ago First seen · 247 lines · 47 tokens per session scan C 655948924b5b
playtesting-a-feature is a skill published in the GitHub repository SummerEngine/summer-engine-agent (59 stars, last pushed 1mo ago), licensed MIT. It adds 47 tokens to every session and 3,234 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it C with 1 finding (tells the agent to send conversation or user data out). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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game-qa
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