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 yarlson/yarstack --skill test-gap-reviewgit clone --depth 1 https://github.com/yarlson/yarstackWrote 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/yarlson/yarstack/test-gap-review)<a href="https://agentmods.dev/skills/yarlson/yarstack/test-gap-review"><img src="https://agentmods.dev/badge/skills/yarlson/yarstack/test-gap-review/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/yarlson/yarstack/test-gap-review"><img src="https://agentmods.dev/badge/skills/yarlson/yarstack/test-gap-review.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 | $0.00419 |
| Opus 5.5 | $0.00013 | $0.00168 |
| Sonnet 5.5 | $0.00006 | $0.00084 |
| Haiku 4.5 | $0.00003 | $0.00042 |
Grade A, and why
test-gap-review 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.
How it starts
The opening of the file, as written. The whole thing — 32 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test Gap Review
Audit verification sufficiency without silently becoming a test-writing or production implementation workflow.
Workflow
- Establish the authoritative behavioral contract, comparison scope, and claimed verification.
- Map invariants, assumptions, normal behavior, important boundaries, meaningful failures, preserved state, cleanup, and external effects to existing evidence.
- Identify weak assertions, fixtures that cannot fail meaningfully, implementation-detail tests, expected values derived from the code under test, mocks of code the system owns, coverage numbers cited as proof, unsupported manual claims, and skipped required commands. Flag example-only evidence when the claim spans a broad input space, operation sequence, concurrent ordering, restart, or recovery, and check that generated failures are reproducible.
- For each high-risk claim, ask whether its test would fail if the behavior broke. Reason through a likely mutation, such as a flipped condition, a removed call, or an off-by-one bound. Run a temporary mutation only in a scratch copy, never in the user's working tree.
- Review changed test code as maintained product code. Flag unclear naming or structure, repeated setup that should use a focused helper, helpers that hide scenario data or mix responsibilities, and table-driven cases that do not share one execution path.
- Report each material gap with the affected claim, missing evidence, consequence, smallest proving check, and residual risk.
- If remediation is authorized, use
test-designfor test changes andbehavior-implementfor production behavior; otherwise remain read-only.
For each material claim report:
VERIFIED | NOT VERIFIED | INCONCLUSIVE
Claim: ...
Evidence: ...
Why: ...
Do not chase coverage percentages, demand a stronger method without a concrete risk, add fake-confidence tests, broaden infrastructure, or change production behavior directly.
Finish when material claims have supported statuses and remaining verification risk is explicit.
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 Changed · +1 lines 661aee75563d
- 1mo ago First seen · 31 lines · 32 tokens per session scan A 9aed6af3ce97
test-gap-review is a skill published in the GitHub repository yarlson/yarstack (3 stars, last pushed 2d ago), licensed MIT. It adds 32 tokens to every session and 419 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 2026-08-31.
Other skills, from other repositories
safe-change
Trace, implement, test, and independently review one bounded software change. Use for ordinary feature, bug-fix, or refactor work after the repository is bootstrapped; do not use for broad repository cleanup, production operations, or undefined rewrites.
gentle-ai-bench
Trigger: bench, journey, journeys, driven mode, gentle-ai-bench, journey corpus, j-numbers, bench axis. Author and verify gentle-ai bench journeys; go test ./bench never proves driven execution.
go-testing
Trigger: Go tests, go test coverage, Bubbletea teatest, golden files. Apply focused Go testing patterns.
include-test-files-that-assert-on-behavior-being-changed-in-decl
When delegating a task affected by this skill, include.
Autonomous Agent Testing
Testing patterns for autonomous AI coding agents like Devin and SWE-Agent including task verification, output validation, sandboxed execution, regression testing for agent behavior, and safety guardrails for autonomous code generation.
ring:running-dev-cycle
Running the backend dev cycle: implements every task in a rolling-wave plan.md (ring:writing-plans format) for a Go/TS service, driving specialist agents through Gate 0 implementation/TDD, Gate 8 parallel review, and Gate 9 validation per epic, elaborating later phases at each phase boundary. Use when starting or…