What is regression-suite?

A tool for maintaining a regression suite, the tests that protect previously working behavior from breaking again. It maps those tests to important product flows and serious fixed bugs.

Use it after fixing a serious bug, before a release, or when reviewing coverage of critical product paths. It audits existing regression tests and can add entries for bugs or key flows.

It reveals missing tests and coverage drift when new features are added. This helps teams catch old bugs returning before a release.

regression-suite — Skill for Claude Code by cenconq25

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 cenconq25/claude-code-app-studio --skill regression-suite

Clone the repo

git clone --depth 1 https://github.com/cenconq25/claude-code-app-studio

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/cenconq25/claude-code-app-studio/regression-suite/github.svg)](https://agentmods.dev/skills/cenconq25/claude-code-app-studio/regression-suite)

Your own site

<a href="https://agentmods.dev/skills/cenconq25/claude-code-app-studio/regression-suite"><img src="https://agentmods.dev/badge/skills/cenconq25/claude-code-app-studio/regression-suite/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/cenconq25/claude-code-app-studio/regression-suite"><img src="https://agentmods.dev/badge/skills/cenconq25/claude-code-app-studio/regression-suite.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 46 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,479 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.

Model	Per session	Once invoked
Fable 5.1	$0.00046	$0.01479
Opus 5	$0.00023	$0.00740
Sonnet 5	$0.00009	$0.00296
Haiku 4.5	$0.00005	$0.00148

Measured 5d ago against content hash 8ac77e1be973, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

regression-suite 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 5d 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.

.claude/skills/regression-suite/SKILL.md · 194 lines

How it starts

The opening of the file, as written. The whole thing — 194 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Regression Suite

A regression suite is the set of tests that must keep passing forever. This skill maintains the explicit list, traces it back to PRD critical paths and known-bug history, and surfaces gaps before release.

Phase 1: Modes

Parse the argument:

--audit (default): re-evaluate the whole suite, identify gaps, suggest fixes.
--add-bug=BUG-ID: add a regression test entry for a specific bug.
--add-path=<name>: add a regression entry for a critical-path PRD flow.

Phase 2: Load the Sources of Truth

Read in parallel:

All PRDs under design/prd/ — extract every Acceptance Criteria block marked critical or revenue-affecting.
production/qa/bugs/ — every closed bug with severity S1 or S2.
tests/regression/ directory — existing regression test files.
tests/regression-suite.md if present — the registry.
production/milestones/ — current milestone scope to know which paths are in active scope.

If tests/regression/ does not exist, propose creating it.

Phase 3: Build the Coverage Matrix

Construct a table mapping each entry to a test file:

Source	Reference	Required	Test file	Status
PRD	onboarding-flow.prd.md AC-3	YES	tests/regression/onboarding/sign_up_test.ts	covered
PRD	paywall.prd.md AC-7	YES	(none)	MISSING
Bug	BUG-042 (force logout)	YES	tests/regression/auth/refresh_token_test.ts	covered
Bug	BUG-051 (paywall double-charge)	YES	(none)	MISSING

Detection rules:

A PRD AC is critical if the AC is tagged Critical:, P0:, or its parent flow is on the launch checklist.
A bug requires a regression test if its severity was S1 or S2 AND its closing comment did not explicitly waive a test.
A test "covers" an entry only if it actually asserts the failing scenario (not just runs the code path). Confirm by reading the test.

Phase 4: Identify Gaps

Three buckets:

PRD critical paths without a regression test — the highest-priority gap. Usually means a launch-blocking flow has no permanent guard.
Closed S1/S2 bugs without a regression test — the bug is fixed but the fix is not pinned, so it can re-emerge.
Drift — tests that reference removed code, fixtures from deleted features, or assertions about replaced UI strings.

Read the full file on GitHub · 194 lines

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.

5d ago First seen · 194 lines · 46 tokens per session scan A 8ac77e1be973

Subscribe to this mod's changes

regression-suite is a skill published in the GitHub repository cenconq25/claude-code-app-studio (40 stars, last pushed 4mo ago), licensed MIT. It adds 46 tokens to every session and 1,479 once invoked, about $0.0002 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 2026-09-03.

Testing

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regression-suite