Borrowing it
Nothing to install: this file belongs to backant-io/jerrycan. 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/backant-io/jerrycan/main/.claude/skills/jerrycan-backend/SKILL.mdgit clone --depth 1 https://github.com/backant-io/jerrycanWrote 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/backant-io/jerrycan/jerrycan-backend)<a href="https://agentmods.dev/skills/backant-io/jerrycan/jerrycan-backend"><img src="https://agentmods.dev/badge/skills/backant-io/jerrycan/jerrycan-backend.svg" alt="Measured on agentmods" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00092 | $0.05530 |
| Opus 5 | $0.00046 | $0.02765 |
| Sonnet 5 | $0.00018 | $0.01106 |
| Haiku 4.5 | $0.00009 | $0.00553 |
Grade A, and why
jerrycan-backend 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 8d 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.
Copies of this mod
2 near-identical copies found in the catalogue:
- jerrycan-backend — 100% identical, 0 lines differ
- jerrycan-backend — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 344 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Building a backend with jerrycan
jerrycan turns a single declarative design.json into a working, tested,
multi-tenant REST backend: it generates the data layer (SeaORM models, dual-dialect
migrations, CRUD repos), typed handler stubs, tenant guards + isolation tests,
acceptance tests, OpenAPI, and app wiring. You (the agent) author the design and
fill in the handler bodies; jerrycan check is the source of truth for "done."
This skill is a guided process. Work through the phases in order. At each
decision point, ask the user — do not guess. Checkpoint after every phase so
neither of you loses the thread. The docs are complete and accurate (jerrycan docs --list); read the relevant page before each step rather than guessing an API.
The golden rules
- Never guess what to build. If you don't know an entity, a field, a status value, an endpoint, a role, or a behavior — ask. One question at a time.
jerrycan checkand the validator are the truth. Loop them; never claim green you haven't seen. Never weaken a generated check to pass it. But a few generated tests are un-greenable BY CONSTRUCTION (a happy-path probe that posts no credential to a login/webhook/API-key endpoint). For those,checkwill not be fully green and that is correct — recognize them (see Phase 5), leave them, and move on; do NOT thrash trying to green them or weaken the handler.- Read the doc page before using a feature.
jerrycan docs <page>/jerrycan explain <CODE>. Start every project by readingjerrycan docs designing. - Flag scope walls EARLY (Phase 2). If the user needs something jerrycan can't express, surface it before you design, and decide together how to handle it.
- Checkpoint after each phase: restate what's decided and what's next.
Phase 0 — Orient (once)
- Confirm jerrycan is available:
jerrycan --version(build it if you're in the framework repo:cargo build -p jerrycanthen usetarget/debug/jerrycan). jerrycan docs --listto see the page index. Readjerrycan docs designingnow — it is the completedesign.jsonreference (every field, type, constraint, and the gotchas). You will author the design from it.- Announce: "I'll use the jerrycan-backend process to design and build this step by step, checking with you at each decision."
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.
- 8d ago First seen · 344 lines · 92 tokens per session scan A db0b2d3b0cb2
jerrycan-backend is a skill published in the GitHub repository backant-io/jerrycan (9 stars, last pushed 6d ago), licensed MIT. It adds 92 tokens to every session and 5,530 once invoked, about $0.0005 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 2026-08-31.
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