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 skills add hookdeck/webhook-skills --skill go1-webhooksgit clone --depth 1 https://github.com/hookdeck/webhook-skillsWrote 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/hookdeck/webhook-skills/go1-webhooks)<a href="https://agentmods.dev/skills/hookdeck/webhook-skills/go1-webhooks"><img src="https://agentmods.dev/badge/skills/hookdeck/webhook-skills/go1-webhooks/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.
<a href="https://agentmods.dev/skills/hookdeck/webhook-skills/go1-webhooks"><img src="https://agentmods.dev/badge/skills/hookdeck/webhook-skills/go1-webhooks.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00046 | $0.01886 |
| Opus 5.5 | $0.00018 | $0.00754 |
| Sonnet 5.5 | $0.00009 | $0.00377 |
| Haiku 4.5 | $0.00005 | $0.00189 |
Grade A, and why
go1-webhooks 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 3d 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.
This is a copy
75% identical to adyen-webhooks — 181 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 146 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Go1 Webhooks
When to Use This Skill
- How do I receive Go1 webhooks?
- How do I verify the
Go1-Signatureheader? - How do I handle
enrollment.create,enrollment.update, orenrollment.deleteevents? - Why is my Go1 webhook signature verification failing?
- Why does the Go1 timestamp look like it is in the wrong unit?
Essential Code (USE THIS)
Go1 signs a webhook only when a secret_key (max 64 characters) is set on it. Every signed request carries:
Go1-Signature: t=<unix MILLISECONDS>,v1=<hex>
v1 is the hex HMAC-SHA256 of "<t>.<raw JSON body>", keyed with secret_key as a UTF-8 string. Use t exactly as received (do not convert it to seconds). This is not Standard Webhooks.
Verification (Node.js)
const crypto = require('crypto');
// rawBody: Buffer of the exact request bytes (express.raw, not express.json)
// toleranceSeconds = 0 (default) skips the timestamp window; a positive value opts in
function verifyGo1Webhook(rawBody, header, secret, toleranceSeconds = 0) {
if (!header || !secret) return false;
const parts = header.split(',').map((p) => p.trim().split('='));
const t = parts.find(([k]) => k === 't')?.[1];
const sigs = parts.filter(([k]) => k === 'v1').map(([, v]) => v);
if (!t || !/^\d+$/.test(t) || sigs.length === 0) return false;
// t is in milliseconds
if (toleranceSeconds > 0 && Math.abs(Date.now() - Number(t)) > toleranceSeconds * 1000) return false;
const expected = crypto.createHmac('sha256', secret).update(`${t}.`).update(rawBody).digest('hex');
return sigs.some((sig) => {
try { return crypto.timingSafeEqual(Buffer.from(sig), Buffer.from(expected)); }
catch { return false; }
});
}
Verification (Python)
import hashlib, hmac, time
def verify_go1_webhook(raw_body: bytes, header: str | None, secret: str, tolerance: int = 0) -> bool:
if not header or not secret:
return False
pairs = [p.strip().split("=", 1) for p in header.split(",") if "=" in p]
t = next((v for k, v in pairs if k == "t"), None)
sigs = [v for k, v in pairs if k == "v1"]
if not t or not (t.isascii() and t.isdigit()) or not sigs:
return False
if tolerance > 0 and abs(time.time() * 1000 - int(t)) > tolerance * 1000: # t is milliseconds
return False
expected = hmac.new(secret.encode(), t.encode() + b"." + raw_body, hashlib.sha256).hexdigest()
return any(hmac.compare_digest(s, expected) for s in sigs)
What ships with it
20 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.
- examples/express/.env.example 407 B
- examples/express/package.json 362 B
- examples/express/README.md 1.4 KB
- examples/express/src/index.js 4.5 KB runs code
- examples/express/test/webhook.test.js 4.9 KB runs code
- examples/fastapi/.env.example 407 B
- examples/fastapi/main.py 4.1 KB runs code
- examples/fastapi/README.md 1.5 KB
- examples/fastapi/requirements.txt 82 B
- examples/fastapi/test_webhook.py 4.4 KB runs code
- examples/nextjs/.env.example 407 B
- examples/nextjs/app/webhooks/go1/route.ts 1.8 KB runs code
- examples/nextjs/lib/go1.ts 2.1 KB runs code
- examples/nextjs/package.json 520 B
- examples/nextjs/README.md 1.4 KB
- examples/nextjs/test/webhook.test.ts 4.5 KB runs code
- examples/nextjs/vitest.config.ts 140 B runs code
- references/overview.md 1.4 KB
- references/setup.md 1.3 KB
- references/verification.md 4.0 KB
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.
- 3d ago First seen · 146 lines · 46 tokens per session scan A e8907bc379ac
go1-webhooks is a skill published in the GitHub repository hookdeck/webhook-skills (94 stars, last pushed yesterday), licensed MIT. It adds 46 tokens to every session and 1,886 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 75% identical to adyen-webhooks, differing in 181 lines, and is treated as a copy.
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