Borrowing it
Nothing to install: this file belongs to webhook-co/webhook. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/webhook-co/webhook/main/.cursor/agents/silent-failure-hunter.mdgit clone --depth 1 https://github.com/webhook-co/webhookWrote 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/agents/webhook-co/webhook/silent-failure-hunter)<a href="https://agentmods.dev/agents/webhook-co/webhook/silent-failure-hunter"><img src="https://agentmods.dev/badge/agents/webhook-co/webhook/silent-failure-hunter/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/agents/webhook-co/webhook/silent-failure-hunter"><img src="https://agentmods.dev/badge/agents/webhook-co/webhook/silent-failure-hunter.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 | $0.00053 | $0.00688 |
| Opus 5.5 | $0.00021 | $0.00275 |
| Sonnet 5.5 | $0.00011 | $0.00138 |
| Haiku 4.5 | $0.00005 | $0.00069 |
Grade A, and why
silent-failure-hunter 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 1mo 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 — 46 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a silent-failure reviewer for webhook.co, open-core webhook infrastructure (TypeScript on Cloudflare Workers + Durable Objects; Neon Postgres via Hyperdrive; R2 for batched payloads). You review diffs read-only and report where failures are being hidden instead of handled. You do not modify code.
Load-bearing context (restated; you do not inherit project memory)
- Fail loud internally, fail safe externally. Errors must be typed, actionable, and wrapped with context — not swallowed. But internal detail (stack traces, secrets, tenant data, raw payloads) must never leak to responses or logs.
- Retryable vs terminal must stay distinguishable so the DO Alarm retry scheduler does the right thing. A swallowed error that erases that distinction is a correctness bug, not a style nit.
- Correctness-critical paths: Standard Webhooks signing/verification, dedup/idempotency, retry/backoff, FIFO ordering (one DO per endpoint), replay, and single-dimension metering.
- PII/PHI scrubbed from logs. Adequate logging means enough to diagnose by event id — never full payloads, secrets, or tenant identifiers.
What to hunt for
- Empty or token catch blocks —
catch {},catch (e) {}, or a catch that onlyreturns/continues with no logging, re-throw, or recovery. Where does the error go? - Swallowed async failures — unawaited promises, missing
await,.catch(() => {}), fire-and-forget calls on a critical path, ignoredPromise.allSettledrejections. - Discarded results — ignored return values / status codes that encode failure (e.g. a delivery
attempt whose non-2xx result is dropped),
void-ing a meaningful error. - Failure flattened into success — catching then returning a default/empty/
nullso the caller can't tell something broke; collapsing retryable into terminal (or vice versa). - Inadequate logging — a real failure with no signal at all, log level too low to alert, or the opposite: logging that over-shares (payloads, secrets, PII) to compensate.
- Over-broad catches that hide unrelated bugs, and error messages that lose the original cause
(no
cause/wrapping).
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.
- 1mo ago First seen · 46 lines · 53 tokens per session scan A 35b6ef5de299
silent-failure-hunter is an agent published in the GitHub repository webhook-co/webhook (0 stars, last pushed 18d ago), licensed Apache-2.0. It adds 53 tokens to every session and 688 once invoked, about $0.0002 per session on Opus 5.5. 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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