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/opengeometry-io/opengeometry/agents-mdgit clone --depth 1 https://github.com/OpenGeometry-io/OpenGeometryWhat 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 | $0.04855 | $0.04855 |
| Opus 5 | $0.02427 | $0.02427 |
| Sonnet 5 | $0.00971 | $0.00971 |
| Haiku 4.5 | $0.00485 | $0.00485 |
Grade A, and why
OpenGeometry AGENTS.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 3d 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 — 444 lines — stays where its author put it; the contents beside it link to each section on GitHub.
AGENTS.md
Single source of truth for AI coding agents (Claude, Codex, Copilot, etc.) working in
this repository. CLAUDE.md and .github/copilot-instructions.md are thin redirects to
this file.
If a subdirectory has stricter instructions, follow both; if they conflict, use the more restrictive rule.
1. Project Identity
OpenGeometry is a browser-native CAD kernel: geometry logic written in Rust,
compiled to WebAssembly, wrapped in TypeScript for Three.js integration.
Published to NPM as opengeometry.
Use cases: browser CAD, AEC/BIM, configurators, geometry-heavy web tools, AI-assisted CAD frontends that need deterministic geometry execution.
Not the right fit for: desktop-native CAD, non-browser runtimes without WebAssembly, visualization-only apps where raw Three.js suffices.
OpenPlans is a downstream application/toolkit built on OpenGeometry. Do not position OpenPlans as the SDK itself.
2. Architecture
App Code (Browser/Node)
│
opengeometry-three ← TypeScript wrapper (main/opengeometry-three/)
│ Shapes: Polygon, Cuboid, Cylinder, Sphere, Wedge, Sweep, Opening, Solid
│ Primitives: Line, Arc, Curve, Polyline, Rectangle
│ Operations: boolean, extrude, offsetPolylineRegions,
│ offsetPolylineGroupRegions, offsetRingVariable
│ Editor: parametric/freeform editing helpers
│ Markup: SpotLabel
│
wasm-bindgen glue ← Generated (main/opengeometry/pkg/, never edited directly)
│
Rust Kernel ← main/opengeometry/src/
├── brep/ B-Rep topology: Vertex, Edge, HalfEdge, Face, Loop, Wire, Shell, Brep, BrepBuilder
├── primitives/ OGPolygon, OGCuboid, OGCylinder, OGSphere, OGWedge, OGSweep, etc.
├── operations/ Triangulation (Earcut), extrude, offset, sweep, winding
├── geometry/ GeometryBuffer (vertex/normal/index serialization), Triangle;
│ 2D toolkit: poly2d, offset2d, boolean2d (winding booleans:
│ nonzero union + positive-winding clip), offset_regions
│ (stroke bands, per-edge ring inset for setback envelopes)
├── spatial/ Placement3D (translation, rotation, scale)
├── scenegraph.rs OGSceneManager + OGEntityRegistry: multi-entity orchestration, BRep snapshots
├── export/ projection (HLR, EdgeClass), pdf (native-only), step, stl, ifc, part21
├── booleans/ Union / Intersection / Subtraction (via boolmesh crate)
├── editor/ Parametric and freeform editing
├── freeform/ OGFreeformGeometry — non-parametric editing wrapper
└── utility/ bgeometry helpers
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.
- 3d ago First seen · 444 lines · 4,855 tokens per session scan A 2f9e6f6930d1
OpenGeometry AGENTS.md is an instructions file published in the GitHub repository OpenGeometry-io/OpenGeometry (468 stars, last pushed 5d ago), licensed MPL-2.0. It adds 4,855 tokens to every session, about $0.0243 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.
Other instructions, from other repositories
web-to-app AGENTS.md
AGENTS.md instructions for shiaho777/web-to-app, covering agents.md, code style, project layout, how the main pieces connect and i18n.
dev3000 AGENTS.md
Instructions for vercel-labs/dev3000, covering agents.md, runtime, local ui, production workflows, browser tools and development rules.
terminal-browser AGENTS.md
AGENTS.md instructions for zenbu-labs/terminal-browser, a project described as: A browser inside your terminal.
Claw3D AGENTS.md
Instructions for iamlukethedev/Claw3D, covering agent instructions, cursor cloud specific instructions, service overview, running the app and lint, typecheck, and tests.
CubbyFlow AGENTS.md
Instructions for utilForever/CubbyFlow, covering agents.md, what this repository is, golden rules, how the core code is shaped and dimensional templates.
inspector copilot-instructions.md
Copilot instructions for modelcontextprotocol/inspector, covering copilot review instructions — mcp inspector, typescript, react and ui (web client), the .withprops() rule and state and effects.