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/loopdive/js2/test262-pass-ratesnpx skills add loopdive/js2 --skill test262-pass-ratesgit clone --depth 1 https://github.com/loopdive/js2What 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 | $0.00048 | $0.00809 |
| Opus 5 | $0.00024 | $0.00404 |
| Sonnet 5 | $0.00010 | $0.00162 |
| Haiku 4.5 | $0.00005 | $0.00081 |
Grade A, and why
test262-pass-rates 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.
How it starts
The opening of the file, as written. The whole thing — 49 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test262 Pass Rates (js-host vs standalone)
Prints the current committed test262 conformance numbers for both compile targets side by side. Reads two committed, CI-refreshed summary files directly — no test run, no network fetch, near-instant.
Data sources
- js-host (gc target):
benchmarks/results/test262-current.json— refreshed by thepromote-baselinejob intest262-sharded.ymlon every push to main. Use.summary(or.official_summaryif present) forpass/total, and.summary.host_free_passfor the narrower "passes with zero host imports" count (not the same as a standalone-target run — see below). - standalone target:
benchmarks/results/test262-standalone-highwater.json— refreshed alongside the js-host baseline (samesha/generated_at). Use.official_pass/.official_totalfor the genuine standalone-target compile+run pass rate.
Both files are committed to the repo (small, ~KB-scale) and always reflect the last successful push-to-main run — check .timestamp/.generated_at and .sha against git -C /workspace log -1 --format=%H to confirm freshness; if the sha doesn't match current main, note that the numbers are as-of the last CI run, not live.
Steps
- Read both files:
node -e "
const host = require('/workspace/benchmarks/results/test262-current.json');
const sa = require('/workspace/benchmarks/results/test262-standalone-highwater.json');
const h = host.official_summary ?? host.summary;
const hostPct = (100 * h.pass / h.total).toFixed(1);
const saPct = (100 * sa.official_pass / sa.official_total).toFixed(1);
const gap = h.pass - sa.official_pass;
console.log('js-host (gc): ' + h.pass + ' / ' + h.total + ' (' + hostPct + '%)');
console.log('standalone: ' + sa.official_pass + ' / ' + sa.official_total + ' (' + saPct + '%)');
console.log('honest gap: ' + gap + ' tests pass under js-host but not standalone');
console.log('baseline sha: ' + host.baseline_sha);
console.log('generated at: ' + host.timestamp);
"
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.
- 2d ago First seen · 49 lines · 48 tokens per session scan A d07a6787c05c
test262-pass-rates is a skill published in the GitHub repository loopdive/js2 (59 stars, last pushed 2d ago), licensed Apache-2.0. It adds 48 tokens to every session and 809 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 2026-08-30.
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