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 agentmods add skills/ericrisco/rsc-harness/e2e-testingnpx skills add ericrisco/rsc-harness --skill e2e-testinggit clone --depth 1 https://github.com/ericrisco/rsc-harnessWrote 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/ericrisco/rsc-harness/e2e-testing)<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/e2e-testing"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/e2e-testing.svg" alt="Measured on agentmods" 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 | $0.00079 | $0.03229 |
| Opus 5 | $0.00039 | $0.01614 |
| Sonnet 5 | $0.00016 | $0.00646 |
| Haiku 4.5 | $0.00008 | $0.00323 |
Grade A, and why
e2e-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 yesterday.
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.
How it starts
The opening of the file, as written. The whole thing — 234 lines — stays where its author put it; the contents beside it link to each section on GitHub.
e2e-testing — drive a real browser, keep it deterministic
You write Playwright tests that walk a real browser through real user journeys — log in, fill a form, check out, navigate across pages — and you keep those tests deterministic enough to gate a merge. The whole game is one tension: e2e tests catch integration bugs nothing else can, and they are the slowest, flakiest layer you own. Every rule below exists to buy back determinism.
Pin @playwright/test and provision browsers with npx playwright install --with-deps. Current
line is Playwright v1.60.x (v1.60.0 shipped 2026-05-11). The _react / _vue selector engines
and the :light Shadow-DOM suffix were removed in v1.58.0 — at any version you should be pinning
they are long gone, so do not reach for them.
Is this even an e2e test?
E2e is the most expensive layer. Spend it only on journeys that cross pages or services. Route the rest out.
| The goal is… | Layer | Why |
|---|---|---|
| A multi-step journey across pages/auth/services in a real browser | e2e (here) | Only a real browser proves the pieces integrate. |
| One component or pure function, rendered in-process (Vitest/Jest, Testing Library) | ../testing-web/SKILL.md |
A browser round-trip to test render logic is slow and flaky for no gain. |
| "Is this page accessible?" — WCAG/ARIA as the deliverable | ../accessibility/SKILL.md |
E2e may call axe inside a test, but auditing a11y is its own skill. |
| "Is this page fast?" — LCP/CWV budgets | ../performance/SKILL.md |
Perf budgets are a different signal than journey correctness. |
| The runner matrix, caching, the pipeline itself | ../github-actions/SKILL.md |
E2e contributes a job; owning the pipeline is theirs. |
| "Is the change done?" — run the gate, collect evidence, then merge | ../verify/SKILL.md |
Running an existing suite as a pre-merge gate is not authoring or stabilizing one. |
Rule: if you can prove it without launching a browser, you should. Push logic down to testing-web.
What ships with it
5 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.
- yesterday First seen · 234 lines · 79 tokens per session scan A 0a3f22b11960
e2e-testing is a skill published in the GitHub repository ericrisco/rsc-harness (64 stars, last pushed 2d ago), licensed MIT. It adds 79 tokens to every session and 3,229 once invoked, about $0.0004 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.
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