prism-verify-regression

prism-verify-regression is a skill for Claude Code, Codex from Shailesh200/prism. It costs 70 tokens per session (490 once invoked), scanned A, original, MIT.

A procedure for checking whether a code change caused regressions, meaning that existing behavior stopped working. It selects tests related to the changed files and says what remains unverified.

In plain words
What is it for?
Use it after an edit to find the relevant tests, run them with the editor's tools, and exercise affected browser screens when the change is user-facing.
Why use it?
Running every test can be slow, while running a few unrelated tests can create false confidence that the change is safe.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it after an edit to find the relevant tests, run them with the editor's tools, and exercise affected browser screens when the change is user-facing.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/shailesh200/prism/prism-verify-regression
Install

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.

Any agent
npx skills add Shailesh200/prism --skill prism-verify-regression
Clone the repo
git clone --depth 1 https://github.com/Shailesh200/prism

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for prism-verify-regression

README.md
[![agentmods](https://agentmods.dev/badge/skills/shailesh200/prism/prism-verify-regression.svg)](https://agentmods.dev/skills/shailesh200/prism/prism-verify-regression)
Your own site
<a href="https://agentmods.dev/skills/shailesh200/prism/prism-verify-regression"><img src="https://agentmods.dev/badge/skills/shailesh200/prism/prism-verify-regression.svg" alt="Measured on agentmods" height="20"></a>
Per session 70 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 490 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00070 $0.00490
Opus 5 $0.00035 $0.00245
Sonnet 5 $0.00014 $0.00098
Haiku 4.5 $0.00007 $0.00049

Measured 2d ago against content hash f7545224ff9f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

prism-verify-regression 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 2d 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.

packages/plugin/skills/prism-verify-regression/SKILL.md · 49 lines

What it actually says

Verify the change, not the whole repository

"Run the tests" is either too slow to be useful or too narrow to be meaningful. The useful version is: work out which tests cover what changed, run those, and say what is still unverified.

The procedure

1. Find what changed. changed_paths if the user did not say. It reports the working-tree and branch diff.

2. Select the suite. test_impact on those paths returns the tests that cover them.

Report gaps out loud. If a changed path has no test covering it, that is the single most valuable finding here — running a green suite that never touches the change is worse than not running it, because it manufactures confidence.

3. Run them with your own tools. Prism selects; it does not execute. Use the editor's test runner, terminal, or task tools.

4. For anything user-facing, drive the browser. If the change touches routes, components or interaction, use your Playwright or browser tools to exercise the affected flow. blast_radius on a changed component tells you which screens to check — that is how you avoid testing only the one page the user mentioned.

5. Report honestly. Three separate categories, never merged:

  • what you ran and it passed
  • what you ran and it failed
  • what you did not run, and why

The third is the one that gets dropped, and it is the one that matters. "No Playwright configured, so the checkout flow is unverified" is a useful sentence. Silence in its place is a false all-clear.

Boundaries

Prism has no test runner and no browser. It reads the repository and names the tests. If the editor has no way to run them, say the suite was selected but not executed — do not report a selection as a result.

Never describe a test as passing unless you saw it pass in this session.

Changes

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.

  1. 2d ago First seen · 49 lines · 70 tokens per session scan A f7545224ff9f

Subscribe to this mod's changes

prism-verify-regression is a skill published in the GitHub repository Shailesh200/prism (3 stars, last pushed today), licensed MIT. It adds 70 tokens to every session and 490 once invoked, about $0.0003 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 2026-09-05.

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