Deno is a runtime that executes JavaScript, TypeScript, and WebAssembly programs outside a browser. Developers use it for applications such as web servers, and the catalogue add-ons provide workflows and guidance for Deno projects.
Borrowing it
Nothing to install: this file belongs to denoland/deno. 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/denoland/deno/main/CLAUDE.mdgit clone --depth 1 https://github.com/denoland/denoWrote 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/instructions/denoland/deno/claude-md)<a href="https://agentmods.dev/instructions/denoland/deno/claude-md"><img src="https://agentmods.dev/badge/instructions/denoland/deno/claude-md/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/instructions/denoland/deno/claude-md"><img src="https://agentmods.dev/badge/instructions/denoland/deno/claude-md.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 | $0.02993 | $0.02993 |
| Opus 5.5 | $0.01197 | $0.01197 |
| Sonnet 5.5 | $0.00599 | $0.00599 |
| Haiku 4.5 | $0.00299 | $0.00299 |
Grade A, and why
deno CLAUDE.md 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 — 434 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Deno Development Guide
Table of Contents
- Git workflow
- High Level Overview
- Quick Start
- Commands
- Testing
- Development Workflows
- Debugging
- Codebase Navigation
- Troubleshooting
Git workflow
Deno uses a GH based standard git workflow. The main branch is main. All
development happens in feature branches, which are then merged into main via
pull requests.
When the feature is finished and ready to for review, follow these steps:
- Create a new git branch, if you haven't already, with a descriptive name
(e.g.,
feature/new-cli-commandorfix/bug-in-worker-threads). - Commit your changes with clear and descriptive commit messages.
- Push your branch to the remote repository.
- Open a pull request (PR) against the
mainbranch on GitHub. - Before committing, make sure
tools/format.jsis run to format your code - Before committing, if only non-Rust was changed, make sure to run
tools/lint.js --jsand fix any lint errors before committing - If you changed Rust code, make sure to run
tools/lint.jsand fix any lint errors before committing - In the PR description, provide a clear summary of the changes you made, why they were necessary, and any relevant context or links to related issues.
- When pushing updates to the PR, make sure to never force push. Create as many commits as you need, all of them get squashed when the PR is merged, so there is no need to rewrite history. This also allows reviewers to see the incremental changes you made in response to feedback.
- Keep your changes minimal, don't do drive-by changes in a PR. If you need to make a change that is not directly related to the PR, create a separate PR for it. This keeps the review process focused and efficient.
High Level Overview
The user visible interface and high level integration is in the deno crate
(located in ./cli).
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 · 434 lines · 2,993 tokens per session scan A 69015aad5ec6
deno CLAUDE.md is an instructions file published in the GitHub repository denoland/deno (108,724 stars, last pushed today), licensed MIT. It adds 2,993 tokens to every session, about $0.0120 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 2026-08-30.
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