What is quality-engineering-selector-stability?

A policy for choosing stable controls and identifiers in automated web and mobile tests. It explains which labels, roles, test IDs, and accessibility identifiers to use and how to name them.

Use it when writing or reviewing UI test locators, adding test IDs or accessibility identifiers, or deciding whether a selector change is safe.

It reduces tests breaking when page structure, styling, or displayed language changes. It also avoids fragile methods such as XPath, position-based selection, and generated class names.

quality-engineering-selector-stability — Skill for Claude Code and Cod

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 HoangNguyen0403/agent-skills-standard --skill quality-engineering-selector-stability

Clone the repo

git clone --depth 1 https://github.com/HoangNguyen0403/agent-skills-standard

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/hoangnguyen0403/agent-skills-standard/quality-engineering-selector-stability/github.svg)](https://agentmods.dev/skills/hoangnguyen0403/agent-skills-standard/quality-engineering-selector-stability)

Your own site

<a href="https://agentmods.dev/skills/hoangnguyen0403/agent-skills-standard/quality-engineering-selector-stability"><img src="https://agentmods.dev/badge/skills/hoangnguyen0403/agent-skills-standard/quality-engineering-selector-stability/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/hoangnguyen0403/agent-skills-standard/quality-engineering-selector-stability"><img src="https://agentmods.dev/badge/skills/hoangnguyen0403/agent-skills-standard/quality-engineering-selector-stability.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 43 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 510 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	$0.00043	$0.00510
Opus 5	$0.00022	$0.00255
Sonnet 5	$0.00009	$0.00102
Haiku 4.5	$0.00004	$0.00051

Measured 5d ago against content hash fcca95212bea, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

quality-engineering-selector-stability 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.

.agents/skills/quality-engineering/quality-engineering-selector-stability/SKILL.md · 61 lines

What it actually says

Quality Engineering: Selector Stability

Priority: P0 (CRITICAL)

Web Ladder

getByRole / getByLabel > getByTestId (data-testid) > attribute CSS. Never XPath, nth-child, or generated class names.

Mobile Ladder

Accessibility id > resource-id / testTag > predicate/uiautomator > XPath. Never XPath.

Framework Map

React/Next.js: data-testid. React Native: testID + accessibilityLabel.
Flutter: Semantics(identifier:) for black-box E2E; WidgetKeys stay for widget tests.
SwiftUI/UIKit: .accessibilityIdentifier. Compose: Modifier.testTag + testTagsAsResourceId = true.

Naming

<screen>-<element>-<role>, kebab-case (e.g. checkout-submit-button).

Insertion Policy

Add ids to leaf interactive/assertable elements only, never layout wrappers. Never rename an existing id — ids are a public contract other tests depend on.

Drift Classes

rename (id changed), restructure (DOM/tree moved), i18n (visible text changed, id untouched).

Anti-Patterns

Text selectors on translated strings, index-based locators (nth), generated/hashed class names.
Using accessibilityLabel as a test id (it is user-facing a11y text, not a stable identifier).
"xpath just for now" — there is no temporary XPath; use the ladder from the first commit.

References

Files

What ships with it

4 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.

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 · 61 lines · 43 tokens per session scan A fcca95212bea

Subscribe to this mod's changes

quality-engineering-selector-stability is a skill published in the GitHub repository HoangNguyen0403/agent-skills-standard (565 stars, last pushed 3d ago), licensed MIT. It adds 43 tokens to every session and 510 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 2026-09-07.

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