webapp-testing

A toolkit for testing local web applications with Playwright, a browser-automation tool. It can check behavior, investigate interface problems, capture screenshots, and collect browser logs.

In plain words
What is it for?
Use it to test local sites, automate browser actions, debug frontend behavior, take screenshots, and inspect console logs.
Why use it?
It verifies what a web app actually does in a browser and provides evidence when the interface or behavior is wrong.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/bh-rat/steer/webapp-testing
Any agent
npx skills add bh-rat/steer --skill webapp-testing
Clone the repo
git clone --depth 1 https://github.com/bh-rat/steer

Made for: Claude Code, Codex.

Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,259 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00054 $0.01259
Opus 5 $0.00027 $0.00629
Sonnet 5 $0.00011 $0.00252
Haiku 4.5 $0.00005 $0.00126

Measured 2d ago against content hash 2f9c6d9ae2ab, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

webapp-testing 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.

The scan reads SKILL.md. This mod also ships 4 executable files (references/console_logging.py, references/element_discovery.py, references/static_html_automation.py, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

examples/rebuilds/webapp-testing/SKILL.md · 129 lines

How it starts

The opening of the file, as written. The whole thing — 129 lines — stays where its author put it; the contents beside it link to each section on GitHub.

webapp-testing

Test and debug local web applications by writing native Python Playwright scripts. The user gets verified frontend behavior, screenshots, console logs, or automation results; every server started for the job is managed, its output captured, and stopped cleanly afterwards.

This skill bundles its own steer runtime at scripts/steer.py; the commands below invoke it with python3 and need nothing installed. Paths are relative to this skill's directory: when your working directory is elsewhere (it usually is), use the skill's full path (python3 <path-to-this-skill>/scripts/steer.py ...).

Before you start

  1. Ground yourself. Run python3 scripts/steer.py context --tools node,npm,playwright and read the snapshot; it tells you the platform, project type, and whether node and playwright exist here before you write any script.
  2. Apply past lessons. Run python3 scripts/steer.py learn show and follow what it says; those lessons came from real previous runs.

Decision tree

User task -> Is it static HTML?
    - Yes -> Read the HTML file directly to identify selectors
             - Works -> Write a Playwright script using those selectors
             - Fails or incomplete -> Treat as dynamic (below)
    - No (dynamic webapp) -> Is the server already running?
             - No  -> Start it managed (see Servers below), then script
             - Yes -> Reconnaissance then action (below)

Servers

Start every server through steer so nothing leaks or zombies, stdout and stderr are captured to a log, and readiness is checked before your automation runs:

python3 scripts/steer.py proc start app --ready-port 5173 -- npm run dev
python3 scripts/steer.py proc status app     # running? port open?
python3 scripts/steer.py proc logs app       # captured output, e.g. startup errors
python3 scripts/steer.py proc stop app       # TERM then KILL, the whole process group

Multiple servers (e.g. backend + frontend):

python3 scripts/steer.py proc start backend --ready-port 3000 --cwd backend -- python3 server.py
python3 scripts/steer.py proc start frontend --ready-port 5173 --cwd frontend -- npm run dev

Read the full file on GitHub · 129 lines

Files

What ships with it

6 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.

  1. 2d ago First seen · 129 lines · 54 tokens per session scan A 2f9c6d9ae2ab

Subscribe to this mod's changes

webapp-testing is a skill published in the GitHub repository bh-rat/steer (7 stars, last pushed 1mo ago), licensed MIT. It adds 54 tokens to every session and 1,259 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 2026-08-31.

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