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 agentmods add instructions/joelmoss/proscenium/claude-mdgit clone --depth 1 https://github.com/joelmoss/prosceniumWhat 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 | $0.01837 | $0.01837 |
| Opus 5 | $0.00919 | $0.00919 |
| Sonnet 5 | $0.00367 | $0.00367 |
| Haiku 4.5 | $0.00184 | $0.00184 |
Grade A, and why
proscenium 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 yesterday.
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 — 161 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CLAUDE.md
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
Project Overview
Proscenium is a Rails engine that provides real-time frontend asset bundling and minification using esbuild. It processes JavaScript, TypeScript, JSX, TSX, and CSS files on-demand with zero configuration and no build step.
Prerequisites
- Ruby >= 3.3.0 (project uses 3.3.8)
- Go 1.25+
- Rails 7.1 to 8.x
Architecture
The project is a hybrid Ruby gem + Go shared library:
- Ruby (lib/proscenium/): Rails integration, middleware, helpers, side-loading logic
- Go (internal/): Core bundling/compilation via esbuild, exposed as a C shared library via FFI
Key Components
lib/proscenium/builder.rb- FFI interface to Go binary, handles build/resolve/compile operationslib/proscenium/railtie.rb- Rails engine configuration and middleware setuplib/proscenium/middleware.rb- Rack middleware that intercepts asset requestslib/proscenium/side_load.rb- Auto-loads JS/CSS alongside views, partials, layoutslib/proscenium/importer.rb- Tracks imported assets for inclusion in HTMLmain.go- C-exported functions (build_to_string,resolve,compile) called from Rubyinternal/builder/- esbuild configuration and build orchestrationinternal/plugin/- Custom esbuild plugins (CSS modules, SVG, i18n, RJS, etc.)
Code Style
- All Ruby files must be styled as per RuboCop.
Development Commands
Compile Go binary (required before running tests)
bundle exec rake compile:local
Run Ruby tests
bin/test
Run a single Ruby test
bin/test test/builder_test.rb
bin/test test/builder_test.rb -n test_method_name
bin/test test/builder_test.rb:12 # line number of the test method definition
Run Go tests
go test ./test
Run Go benchmarks
go test ./internal/builder -bench=. -run="^$" -count=10 -benchmem
Build gems for all platforms
bundle exec rake build
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.
- yesterday First seen · 161 lines · 1,837 tokens per session scan A 4fcfbd317e9a
proscenium CLAUDE.md is an instructions file published in the GitHub repository joelmoss/proscenium (104 stars, last pushed 7d ago), licensed MIT. It adds 1,837 tokens to every session, about $0.0092 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 2026-09-01.
Other instructions, from other repositories
electron CLAUDE.md
Instructions for electron/electron, covering electron development guide, running nodemodules binaries, project overview, directory structure and build tools setup.
electron copilot-instructions.md
Instructions for electron/electron, covering copilot instructions for electron, build system, linting, running a single test and example: npm run test -- -g "ipc".
biome AGENTS.md
Instructions for biomejs/biome, covering agent guidelines for contributing to biome, communication, before editing, implementation gate and final review.
biome CLAUDE.md
Instructions for biomejs/biome, a project described as: A toolchain for web projects, aimed to provide functionalities to maintain them. Biome offers formatter and linter, usable via CLI and LSP.
bun AGENTS.md
AGENTS.md instructions for oven-sh/bun, a project described as: Incredibly fast JavaScript runtime, bundler, test runner, and package manager – all in one.
bun CLAUDE.md
Claude Code instructions for oven-sh/bun, covering building and running bun, build commands, changes that don't require a build, testing and running tests.