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 kensaurus/cursor-kenji --skill backend-observabilitygit clone --depth 1 https://github.com/kensaurus/cursor-kenjiWrote 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/kensaurus/cursor-kenji/backend-observability)<a href="https://agentmods.dev/skills/kensaurus/cursor-kenji/backend-observability"><img src="https://agentmods.dev/badge/skills/kensaurus/cursor-kenji/backend-observability.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 5.1 | $0.00069 | $0.01803 |
| Opus 5 | $0.00034 | $0.00901 |
| Sonnet 5 | $0.00014 | $0.00361 |
| Haiku 4.5 | $0.00007 | $0.00180 |
Grade A, and why
backend-observability 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 5d 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 — 90 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Observability Instrumentation
Degree of freedom: MIXED. What to wrap and alert on [HIGH freedom];
correlation ids, PII redaction, and the DoD [LOW freedom — run exactly].
How to reason
- Observe — which ids, logs, spans, and PII already exist
- Interpret — can you pivot error ↔ trace ↔ log ↔ user from any one?
- Classify — add-correlation / convert-console / redact / wrap-span / alert
- Severity — uncorrelated prod 500 outranks a missing debug field
Worked example
Observe: checkout 500 in Sentry has no request_id; pino logs the cart id; no LLM (Langfuse unused). Interpret: cannot pivot error → logs; webhook still
console.logs. Classify: ALS request_id on logs +Sentry.setTag; convert console to pino; redactAuthorization. Verify: one id on the Sentry event and the log line;beforeSendstrips the header.
Self-critique before reporting
- Correlated — same request/trace id on the log, Sentry, and Langfuse
- Redacted — deny-list at the logger +
beforeSend, not per-call hope - Leveled — no
console.login prod; handled paths are noterror - Right owner — plan-only audit →
plan-error-handling; investigate a Sentry issue →debug-sentry-monitor
The build-time counterpart to your monitoring stack. The Sentry plugin installs the SDK;
debug-sentry-monitortriages after the fact;audit-langfuse-llmaudits LLM traces. about instrumenting correctly while you build so those tools have signal to work with — and so a 3am incident is debuggable.
When this fires
Adding logging / tracing / metrics to new code, reviewing instrumentation, or fixing "we can't tell what happened in prod." Not for installing an SDK (use the Sentry/Langfuse plugins) or post-hoc triage (use the monitor/audit skills).
The one rule that matters most: correlation [LOW freedom — run exactly]
A prod incident is only debuggable if you can pivot error ↔ trace ↔ log ↔ user from any one of them. Make every layer share an id.
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.
- 5d ago First seen · 90 lines · 69 tokens per session scan A c9bd945a4840
backend-observability is a skill published in the GitHub repository kensaurus/cursor-kenji (9 stars, last pushed 10d ago), licensed MIT. It adds 69 tokens to every session and 1,803 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 2026-09-03.
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Diagnose a bounded backend or multi-service failure from GitHub Issues, Jira, Aone, user-provided exports, logs, traces, responses, stack traces, or job records. Use when a service, API, RPC, worker, queue, CLI, or scheduled job bug needs correlation through the project's existing observability route before repair; do…
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Create a high-signal bug issue or PR in the repo that owns the defect. Use this whenever the user asks to report, file, open, or triage a LazyCodex, lazycodex-ai, omo-codex, Codex plugin, or upstream Codex CLI bug, especially when they need source-backed root cause, reproduction steps, fix guidance, and GitHub routing.
ast-grep
Searches and rewrites code by AST shape across 25 languages. Use when the target is a syntax pattern (every call/class/import shaped like X, a codemod, a YAML rule) rather than literal text; for plain strings, comments, or filenames, use rg.