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 agentmods add skills/abstractonion/cadence/nullable-equalitynpx skills add abstractonion/cadence --skill nullable-equalitygit clone --depth 1 https://github.com/abstractonion/cadenceWrote 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/abstractonion/cadence/nullable-equality)<a href="https://agentmods.dev/skills/abstractonion/cadence/nullable-equality"><img src="https://agentmods.dev/badge/skills/abstractonion/cadence/nullable-equality.svg" alt="Measured on agentmods" 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 | $0.00036 | $0.00191 |
| Opus 5 | $0.00018 | $0.00096 |
| Sonnet 5 | $0.00007 | $0.00038 |
| Haiku 4.5 | $0.00004 | $0.00019 |
Grade A, and why
nullable-equality 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 3d 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
TypeScript: compare nullables with == / != null
For nullability checks specifically, use the loose-equality form.
Do
if (value == null) { ... } // matches null AND undefined
if (value != null) { ... } // narrows to NonNullable<T>
Don't
if (value === null || value === undefined) { ... } // verbose
if (!value) { ... } // wrong for 0, "", false
if (value === undefined) { ... } // misses null
This is the only place loose equality is acceptable. Everywhere else, use === / !==.
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.
- 3d ago First seen · 26 lines · 36 tokens per session scan A 7047aae61342
nullable-equality is a skill published in the GitHub repository abstractonion/cadence (4 stars, last pushed 2mo ago), licensed MIT. It adds 36 tokens to every session and 191 once invoked, about $0.0002 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.
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