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 jabrena/plinth --skill 057-design-feature-togglesgit clone --depth 1 https://github.com/jabrena/plinthWrote 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/jabrena/plinth/057-design-feature-toggles)<a href="https://agentmods.dev/skills/jabrena/plinth/057-design-feature-toggles"><img src="https://agentmods.dev/badge/skills/jabrena/plinth/057-design-feature-toggles/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/jabrena/plinth/057-design-feature-toggles"><img src="https://agentmods.dev/badge/skills/jabrena/plinth/057-design-feature-toggles.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00103 | $0.00880 |
| Opus 5 | $0.00051 | $0.00440 |
| Sonnet 5 | $0.00021 | $0.00176 |
| Haiku 4.5 | $0.00010 | $0.00088 |
Grade A, and why
057-design-feature-toggles 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 12d 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 — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Feature Toggles Design
Guide Java Enterprise developers through safe feature toggle design and lifecycle management. This is an interactive SKILL.
What is covered in this Skill?
- Deciding when a feature toggle is appropriate versus a branch, configuration change, deployment change, or parallel change
- Classifying release toggles, operational kill switches, experiment toggles, permission toggles, and migration toggles
- Designing typed toggle ownership, defaults, evaluation scope, fallback behavior, observability, and rollback controls
- Implementing toggles in Java services without scattering flag checks or creating hidden long-term complexity
- Reviewing toggles for release, rollback, security, privacy, concurrency, and maintenance risk
- Testing both enabled and disabled paths, configuration failure behavior, rollout rules, and cleanup readiness
Constraints
Use feature toggles as explicit, owned runtime control points rather than hidden conditional complexity.
- MUST read
references/057-design-feature-toggles.mdbefore applying feature toggle guidance - MUST classify the toggle type, owner, expected lifetime, default state, rollout audience, and removal trigger before recommending implementation
- MUST design safe defaults, fallback behavior, observability, and rollback behavior for runtime evaluation failures
- MUST keep toggle evaluation centralized, typed, and testable instead of scattering raw configuration lookups through business logic
- MUST include cleanup expectations for temporary toggles before implementation is considered complete
- MUST NOT use feature toggles to hide incomplete design decisions, weaken security controls, or leave permanent branches without explicit ownership
When to use this skill
- Design a feature toggle strategy
- Review this feature flag implementation
- Add a kill switch safely
- Plan a canary or staged rollout in a Java service
- Test toggle on and off paths
- Clean up an expired feature toggle
- Decide whether this runtime behavior change needs a toggle
What ships with it
1 file 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.
- 12d ago First seen · 72 lines · 103 tokens per session scan A 3a320f37388a
057-design-feature-toggles is a skill published in the GitHub repository jabrena/plinth (439 stars, last pushed yesterday), licensed Apache-2.0. It adds 103 tokens to every session and 880 once invoked, about $0.0005 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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