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 jeremylongworth-source/AgentSkills --skill regression-checkgit clone --depth 1 https://github.com/jeremylongworth-source/AgentSkillsWrote 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/jeremylongworth-source/agentskills/regression-check)<a href="https://agentmods.dev/skills/jeremylongworth-source/agentskills/regression-check"><img src="https://agentmods.dev/badge/skills/jeremylongworth-source/agentskills/regression-check/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/jeremylongworth-source/agentskills/regression-check"><img src="https://agentmods.dev/badge/skills/jeremylongworth-source/agentskills/regression-check.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 | $0.00057 | $0.00402 |
| Opus 5.5 | $0.00023 | $0.00161 |
| Sonnet 5.5 | $0.00011 | $0.00080 |
| Haiku 4.5 | $0.00006 | $0.00040 |
Grade A, and why
regression-check 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.
What it actually says
Regression Check
Core Workflow
- Identify the changed behavior, affected surfaces, dependencies, and user journeys.
- Map the change to known invariants, prior bugs, adjacent workflows, and compatibility requirements.
- Start with targeted checks for the changed behavior and required repository gates. Add broader regression tests for plausible side effects; do not require every coverage type for a small change.
- Separate automated coverage from manual, exploratory, visual, accessibility, performance, or data checks.
- Specify test data, environment, permissions, feature flags, and observability needed for verification.
- Stop after relevant checks pass unless new changes, failures, or unresolved risks justify more testing. State residual risk and, when requested, the release gate recommendation.
Safety Rules
- Do not treat tests as passed unless output or evidence is available.
- Do not rely only on happy-path checks for auth, billing, data, migrations, or customer-facing workflows.
- Escalate when there is no reproducible baseline, missing test data, unclear owner, or high-risk production dependency.
Deliverable Shape
For regression work, cover the applicable items below; combine them for small changes and do not invent a release ceremony for a local fix:
- Changed surface
- Regression risk areas
- Direct verification tests
- Broader regression tests
- Automation versus manual coverage
- Test data and environment needs
- Release gate recommendation
- Residual risk
References
- Read
references/regression-check-checklist.mdwhen planning or reviewing regression coverage.
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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 Changed · +4 lines 4426fcbad3f5
- 1mo ago First seen · 48 lines · 57 tokens per session scan A e2ffa0f000df
regression-check is a skill published in the GitHub repository jeremylongworth-source/AgentSkills (1 stars, last pushed 17d ago), licensed MIT. It adds 57 tokens to every session and 402 once invoked, about $0.0002 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 2026-09-03.
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