core

A set of repository-wide rules that protect important design boundaries and data formats. A repository is the project's source-code collection; these rules cover how its packages, editor, runtime, saved data, and tests fit together.

In plain words
What is it for?
Use it as guidance for most coding tasks, especially changes involving package dependencies, saved scene data, editor mutations, browser files, React views, or testing.
Why use it?
Without shared boundaries, code can become tightly coupled, saved files can become unstable, and editor-only code can leak into shipped games. The rules keep changes consistent and reversible.

Cursor rule for Cursor

Install

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.

agentmods
npx agentmods add rules/andvolodko/html5-game-editor/core
Clone the repo
git clone --depth 1 https://github.com/andvolodko/html5-game-editor

Made for: Cursor.

Per session 258 This file is loaded in full into every session.
When invoked 258 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00258 $0.00258
Opus 5 $0.00129 $0.00129
Sonnet 5 $0.00052 $0.00052
Haiku 4.5 $0.00026 $0.00026

Measured 2d ago against content hash 070ad468a394, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

core 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.

.cursor/rules/core.mdc · 20 lines

What it actually says

Core invariants

Consult PROJECT.md for repository orientation when needed. For architectural or cross-package changes, consult the relevant documentation linked from PROJECT.md. Do not load unrelated documentation for localized changes.

  1. Runtime packages must not depend on editor packages. Games must ship without editor code.
  2. Serialized scene/domain data must stay serializable, deterministic, Git-friendly, and renderer-independent.
  3. Never persist PIXI.* or THREE.* runtime instances in scene/domain models.
  4. Persisted asset references must use stable assetId values, not filesystem paths.
  5. Browser filesystem access must go through project-server. Constrain paths to the active project root.
  6. Preserve package dependency direction. Domain packages must not import apps or editor UI. Avoid cycles.
  7. User-visible editor mutations should go through commands so undo/redo works. One completed gesture = one command.
  8. React is a view layer. It must not be the source of truth for scene/domain state.
  9. Reuse existing architecture before introducing new abstractions. Do not make unrelated changes.
  10. After implementation, run the relevant tests and typecheck for affected packages.
Changes

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.

  1. 2d ago First seen · 20 lines · 258 tokens per session scan A 070ad468a394

Subscribe to this mod's changes

core is a cursor rule published in the GitHub repository andvolodko/html5-game-editor (5 stars, last pushed 7d ago), licensed MIT. It adds 258 tokens to every session, about $0.0013 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.