Borrowing it
Nothing to install: this file belongs to act-sdk/act-sdk-js. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/act-sdk/act-sdk-js/main/.agents/skills/harden/SKILL.mdgit clone --depth 1 https://github.com/act-sdk/act-sdk-jsWrote 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/act-sdk/act-sdk-js/harden)<a href="https://agentmods.dev/skills/act-sdk/act-sdk-js/harden"><img src="https://agentmods.dev/badge/skills/act-sdk/act-sdk-js/harden/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/act-sdk/act-sdk-js/harden"><img src="https://agentmods.dev/badge/skills/act-sdk/act-sdk-js/harden.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 | $0.00032 | $0.02178 |
| Opus 5.5 | $0.00013 | $0.00871 |
| Sonnet 5.5 | $0.00006 | $0.00436 |
| Haiku 4.5 | $0.00003 | $0.00218 |
Grade A, and why
harden 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.
This is a copy
92% identical to harden — 11 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 357 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Strengthen interfaces against edge cases, errors, internationalization issues, and real-world usage scenarios that break idealized designs.
Assess Hardening Needs
Identify weaknesses and edge cases:
-
Test with extreme inputs:
- Very long text (names, descriptions, titles)
- Very short text (empty, single character)
- Special characters (emoji, RTL text, accents)
- Large numbers (millions, billions)
- Many items (1000+ list items, 50+ options)
- No data (empty states)
-
Test error scenarios:
- Network failures (offline, slow, timeout)
- API errors (400, 401, 403, 404, 500)
- Validation errors
- Permission errors
- Rate limiting
- Concurrent operations
-
Test internationalization:
- Long translations (German is often 30% longer than English)
- RTL languages (Arabic, Hebrew)
- Character sets (Chinese, Japanese, Korean, emoji)
- Date/time formats
- Number formats (1,000 vs 1.000)
- Currency symbols
CRITICAL: Designs that only work with perfect data aren't production-ready. Harden against reality.
Hardening Dimensions
Systematically improve resilience:
Text Overflow & Wrapping
Long text handling:
/* Single line with ellipsis */
.truncate {
overflow: hidden;
text-overflow: ellipsis;
white-space: nowrap;
}
/* Multi-line with clamp */
.line-clamp {
display: -webkit-box;
-webkit-line-clamp: 3;
-webkit-box-orient: vertical;
overflow: hidden;
}
/* Allow wrapping */
.wrap {
word-wrap: break-word;
overflow-wrap: break-word;
hyphens: auto;
}
Flex/Grid overflow:
/* Prevent flex items from overflowing */
.flex-item {
min-width: 0; /* Allow shrinking below content size */
overflow: hidden;
}
/* Prevent grid items from overflowing */
.grid-item {
min-width: 0;
min-height: 0;
}
Responsive text sizing:
- Use
clamp()for fluid typography - Set minimum readable sizes (14px on mobile)
- Test text scaling (zoom to 200%)
- Ensure containers expand with text
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 · 357 lines · 32 tokens per session scan A 6114cdc92bd9
harden is a skill published in the GitHub repository act-sdk/act-sdk-js (3 stars, last pushed 4mo ago), licensed MIT. It adds 32 tokens to every session and 2,178 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 92% identical to harden, differing in 11 lines, and is treated as a copy.
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