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 fusengine/agents --skill breaking-changesgit clone --depth 1 https://github.com/fusengine/agentsWrote 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/fusengine/agents/breaking-changes)<a href="https://agentmods.dev/skills/fusengine/agents/breaking-changes"><img src="https://agentmods.dev/badge/skills/fusengine/agents/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/fusengine/agents/breaking-changes"><img src="https://agentmods.dev/badge/skills/fusengine/agents/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 | $0.00030 | $0.00387 |
| Opus 5.5 | $0.00012 | $0.00155 |
| Sonnet 5.5 | $0.00006 | $0.00077 |
| Haiku 4.5 | $0.00003 | $0.00039 |
Grade A, and why
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 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.
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.
What it actually says
Breaking Changes Detection Skill
Overview
Compares Claude Code API changes against our plugin ecosystem to detect compatibility issues.
API Surface File
The api-surface.md reference contains our current known API:
- Hook types and their matchers
- Agent frontmatter fields
- Plugin manifest schema
- Skill SKILL.md format
- Script CLI flags used
Detection Workflow
- Load current api-surface.md
- Fetch latest Claude Code API docs
- Diff for added/changed/removed APIs
- Grep our plugins for each changed API
- Report with file:line impact mapping
Impact Assessment
| Change Type | Severity | Example |
|---|---|---|
| Removed API | BREAKING | Hook type deleted |
| Changed schema | BREAKING | Frontmatter field renamed |
| New required field | BREAKING | Mandatory new param |
| Deprecated API | DEPRECATED | Old hook still works |
| New optional API | NEW | New hook type added |
References
What ships with it
2 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.
- 1mo ago First seen · 49 lines · 30 tokens per session scan A 8659236400ec
breaking-changes is a skill published in the GitHub repository fusengine/agents (32 stars, last pushed 7d ago), licensed MIT. It adds 30 tokens to every session and 387 once invoked, about $0.0001 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 2026-09-03.
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transcript-replay
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