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 056-design-avoid-breaking-changesgit 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/056-design-avoid-breaking-changes)<a href="https://agentmods.dev/skills/jabrena/plinth/056-design-avoid-breaking-changes"><img src="https://agentmods.dev/badge/skills/jabrena/plinth/056-design-avoid-breaking-changes/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/056-design-avoid-breaking-changes"><img src="https://agentmods.dev/badge/skills/jabrena/plinth/056-design-avoid-breaking-changes.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 | $0.00106 | $0.00845 |
| Opus 5.5 | $0.00042 | $0.00338 |
| Sonnet 5.5 | $0.00021 | $0.00169 |
| Haiku 4.5 | $0.00011 | $0.00085 |
Grade A, and why
056-design-avoid-breaking-changes 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 24d 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 — 69 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Avoid Breaking Changes
Review planned repository changes for breaking-change and compatibility risk before implementation or release promotion. This is an interactive SKILL.
What is covered in this Skill?
- Command contract compatibility: names, inputs, owning agents, outputs, safeguards, installer registration, and command inventories
- Skill routing compatibility: identifiers, metadata, descriptions, triggers, references, generated local output, and acceptance coverage
- Generated-output ownership: XML/source files versus
.agents/skills, publicskills/,.cursor/commands,.cursor/rules, anddocs/ - Source and generator contracts: XML, XInclude, XSLT, Maven modules, schema expectations, and module validation
- README, localized README, changelog, migration, and deprecation guidance
- External and runtime contracts: APIs, schemas, data formats, configuration keys, persistence, CLI behavior, and CI expectations
- Structured compatibility reports with severity-ranked findings and validation guidance
Constraints
Keep the review evidence-based, read-only, and scoped to compatibility risk unless the user explicitly asks for implementation.
- MUST read
references/056-design-avoid-breaking-changes.mdbefore producing compatibility guidance - MUST identify the source artifacts reviewed and the compatibility surfaces considered
- MUST distinguish confirmed breaking changes, potential risks, non-breaking changes, and unknowns that need maintainer decision
- MUST include migration, deprecation, validation, or release-note guidance for intentional breaking changes
- MUST respect repository source ownership: edit XML and source docs, regenerate generated output through documented workflows, and avoid direct generated-output edits unless the repository explicitly owns that file
- MUST NOT modify plans, specs, source files, generated outputs, or issue descriptions during review unless the user explicitly requests implementation
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.
- 24d ago Changed 46e2b58128f2
- 1mo ago First seen · 69 lines · 106 tokens per session scan A f393e70d5b13
056-design-avoid-breaking-changes is a skill published in the GitHub repository jabrena/plinth (454 stars, last pushed 2d ago), licensed Apache-2.0. It adds 106 tokens to every session and 845 once invoked, about $0.0004 per session on Opus 5.5. 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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phx-pr-review
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Run an A/B codex review experiment — holistic codex review vs 3 focused dimension passes (security, ecto, liveview) on the branch diff, classify findings, report a panel-value verdict. Use when the branch is fresh, before any codex review runs.
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