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/needlestack/gmc64/claude-mdgit clone --depth 1 https://github.com/needlestack/gmc64What 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 | $0.11120 | $0.11120 |
| Opus 5 | $0.05560 | $0.05560 |
| Sonnet 5 | $0.02224 | $0.02224 |
| Haiku 4.5 | $0.01112 | $0.01112 |
Grade A, and why
gmc64 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 2d 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 — 919 lines — stays where its author put it; the contents beside it link to each section on GitHub.
GMC64 Technical Documentation
A faithful, modern recreation of Garry Kitchen's GameMaker (Activision, 1985).
gmc64 lets you build, run, and edit C64-style games in the browser, with original-format .PRG, .SPR, .SND, .SNG, and .PIC files stored on D64 disk images. Files round-trip cleanly with the original 1985 GameMaker disk running on real C64 hardware.
This document is the internal engineering reference — architecture, file formats, gotchas, and recipes for working in the codebase. Reader-facing overview lives in README.md.
Quick Reference
| Item | Value |
|---|---|
| Music tempo | gmMusic.BASE_BPM = 140 (tempo 80 = 140 BPM) |
| Screen resolution | 320×200 native, CSS scales to display |
| Coordinate system | GM fat pixels: X 12-171, Y 50-249 → 320×200: (x-12)*2, y-50 |
| Movement formula | X: speed / 46, Y: speed / 31.5 at 60fps (C64 pixels aren't square) |
| Animation formula | frame_skip = 32 - animSpeed |
| File separator | / not . (PETSCII): PLAYER/SPR not PLAYER.SPR |
Project Structure
├── editor.html Program editor/runner (AST-based VM)
├── sprite-maker.html Sprite editor
├── scene-maker.html Scene editor
├── sound-maker.html Sound effect editor
├── music-maker.html Music editor
├── js/
│ ├── gmRuntime.js VM execution, sprites, collision
│ ├── gmParser.js Bytecode → AST parsing
│ ├── gmSprite.js Sprite parsing/rendering
│ ├── gmScene.js Scene parsing (indexed pixel buffer)
│ ├── gmSound.js Sound effects (Web Audio + SID emulation)
│ ├── gmMusic.js Music playback (3-channel)
│ ├── gmDisk.js D64 disk + localStorage persistence
│ ├── gmEditor.js Instruction editor UI
│ ├── gmOpcodes.js Opcode definitions
│ ├── gmCharset.js C64 font rendering
│ ├── gmTools.js Shared utilities
│ ├── d64lib.js Pure D64/1541 disk parsing
│ ├── c64lib.js C64 palette, PETSCII decoding
│ ├── c64Screen.js 320×200 canvas wrapper
│ ├── gif.js GIF library (jnordberg/gif.js)
│ └── gifWorkerBlob.js GIF worker as inline blob (avoids file:// security restrictions)
├── css/
│ └── gm-ui.css Master stylesheet (C64 colors, fonts, components)
├── tests/
│ ├── *.test.js Vitest test files
│ ├── generate-golden-*.js Golden file generators
│ ├── golden/ Golden snapshot files (JSON)
│ └── disks/ Test D64 disk images
├── tools/
│ ├── screenshot.js Puppeteer screenshot utility
│ └── hex-viewer.html Hex dump viewer
└── docs/
├── TODO.md Future improvements
└── references/ Reference materials
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.
- 2d ago First seen · 919 lines · 11,120 tokens per session scan A be75fd0f7e7d
gmc64 CLAUDE.md is an instructions file published in the GitHub repository needlestack/gmc64 (11 stars, last pushed 1mo ago), licensed MIT. It adds 11,120 tokens to every session, about $0.0556 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 2026-08-30.
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Instructions for librosa/librosa, covering agent interaction policy for librosa, 1. automated platform interactions, 2. exception for project-authorized automation and 3. machine-readable directive.
cc-3-8-x-mcp AGENTS.md
Instructions for HappyLifeOk/cc-3-8-x-mcp, covering agents.md, 允许入口, 绑定当前项目, gateway tool and 预览 url.
tilawa AGENTS.md
Instructions for yazinsai/tilawa, covering tilawa, layout, sdk architecture, public surface (@tilawa/core) and build & test the sdk.
elah AGENTS.md
Instructions for elahlabs/elah, covering agents.md, what this is, layout, commands and the export worker.
autodoubao AGENTS.md
AGENTS.md instructions for linxxcat000/autodoubao, covering autodoubao project instructions, durable context, using the mcp, browser constraints and verification.
contexture webrtc.instructions.md
Instructions for AcKeskin/contexture, covering webrtc rules, data channels and reliability, media and tracks and peer connection lifecycle.