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 burin-labs/harn --skill harn-testinggit clone --depth 1 https://github.com/burin-labs/harnWrote 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/burin-labs/harn/harn-testing)<a href="https://agentmods.dev/skills/burin-labs/harn/harn-testing"><img src="https://agentmods.dev/badge/skills/burin-labs/harn/harn-testing/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/burin-labs/harn/harn-testing"><img src="https://agentmods.dev/badge/skills/burin-labs/harn/harn-testing.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 | $0.00024 | $0.02137 |
| Opus 5.5 | $0.00010 | $0.00855 |
| Sonnet 5.5 | $0.00005 | $0.00427 |
| Haiku 4.5 | $0.00002 | $0.00214 |
Grade A, and why
harn-testing 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 25d 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 — 217 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Harn testing
Use this skill to choose evidence that can falsify the claim being made.
Pair it with [[harn-probe]] for uncertain runtime facts, [[harn-orchestration]] for workflow ownership, and [[harn-product-quality]] for launch behavior.
Start from the claim
- Write the claim in observable terms.
- Name a plausible falsifier.
- Identify the owning module and public interface.
- Choose the lowest test altitude that can falsify the claim.
- Add higher-altitude evidence when the claim crosses adapters or surfaces.
- Do not count tests as proof; map evidence to claims.
- Record what remains outside the evidence.
Test altitude
- Pure language semantics: conformance fixture.
- Parser, type, lint, or format behavior: focused crate test plus conformance.
- Runtime module behavior: test through the public runtime interface.
- Workflow behavior: deterministic harness test.
- Adapter contract: production and in-memory adapters through the same seam.
- Product behavior: canonical path end to end.
- Liveness: progress, interruption, recovery, terminal state.
- Model quality: multiple trials with a calibrated evaluator.
Determinism
- Use
mock_time, paused Tokio time, and explicit advancement. - Subscribe to events rather than polling.
- Use
OrchestratorHarnessfor workflow state. - Use deterministic provider and tool adapters.
- Seed randomness and record the seed.
- Avoid
sleep, wall-clock deadlines, and shortrecv_timeout. - Avoid network dependencies in deterministic suites.
- Assert on typed events and outcomes rather than incidental log order.
Interface tests
- Tests and callers should cross the same interface.
- Assert observable outcomes, errors, receipts, and state transitions.
- Do not test through private seams merely because they are convenient.
- Replace shallow-module tests when a deeper owning interface supersedes them.
- Keep test setup smaller than the behavior under test.
- Use production-shaped configuration defaults.
- Verify closed error variants and diagnostic codes.
- Keep fixtures minimal and readable.
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.
- 25d ago Changed · +6 lines b3faa25da533
- 1mo ago Changed · +14 lines ed2bbdcc1142
- 1mo ago First seen · 197 lines · 24 tokens per session scan A a532909eacd2
harn-testing is a skill published in the GitHub repository burin-labs/harn (28 stars, last pushed today), licensed Apache-2.0. It adds 24 tokens to every session and 2,137 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 2026-08-30.
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