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 curiositech/windags-skills --skill api-versioning-backward-compatibilitygit clone --depth 1 https://github.com/curiositech/windags-skillsWrote 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/curiositech/windags-skills/api-versioning-backward-compatibility)<a href="https://agentmods.dev/skills/curiositech/windags-skills/api-versioning-backward-compatibility"><img src="https://agentmods.dev/badge/skills/curiositech/windags-skills/api-versioning-backward-compatibility/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/curiositech/windags-skills/api-versioning-backward-compatibility"><img src="https://agentmods.dev/badge/skills/curiositech/windags-skills/api-versioning-backward-compatibility.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 | $0.00080 | $0.01322 |
| Opus 5 | $0.00040 | $0.00661 |
| Sonnet 5 | $0.00016 | $0.00264 |
| Haiku 4.5 | $0.00008 | $0.00132 |
Grade A, and why
api-versioning-backward-compatibility 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 9d 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.
The source is not reproduced here
A licence we could not identify
The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.
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.
- 9d ago First seen · 135 lines · 80 tokens per session scan A 5f8b2813d7cf
api-versioning-backward-compatibility is a skill published in the GitHub repository curiositech/windags-skills (10 stars, last pushed 1mo ago), with no licence file. It adds 80 tokens to every session and 1,322 once invoked, about $0.0004 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 2026-08-31.
Other skills, from other repositories
API Versioning Testing
Testing API versioning strategies including URL path, header, and query parameter versioning with backward compatibility validation.
deprecation
Use when retiring a public API, feature, integration, service or legacy path without abandoning consumers. Inventories usage, classifies advisory vs compulsory migration, ships compatibility/tooling, assigns owners and gates removal on evidence. NOT live schema expand-contract (db-migrations), NOT replacement API…
backend-api-versioning
Use this skill when the user says 'API versioning', 'version strategy', 'URI versioning', 'header versioning', 'content negotiation', 'accept header', 'breaking change', 'API migration', 'deprecate endpoint', 'sunset endpoint'. This skill manages API version transitions using URI, header, or content-negotiation…
deprecation-and-migration
Manages safe API deprecation and system migrations. Use when removing or changing existing APIs, migrating databases, upgrading dependencies, or migrating between architectural patterns without breaking existing consumers.
API Schema Evolution Testing
Testing API schema evolution patterns including additive changes, field deprecation, type widening, and backward-compatible migration strategies.
Library Backward Compatibility
Testing library backward compatibility including public API surface verification, semver compliance, TypeScript type compatibility, and migration path validation.