implement-runtime-feature

A guide for adding gameplay and other running-game features to a game runtime, separate from editor screens and controls.

In plain words
What is it for?
Use it for audio, input, timers, scene changes, asset loading, script lifecycle, spawning, and other shared game-runtime behavior.
Why use it?
It keeps runtime code independent from the editor, making shared systems safer to use in previews and standalone games.

Skill for Claude CodeCodexCursor

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 skills/andvolodko/html5-game-editor/implement-runtime-feature
Any agent
npx skills add andvolodko/html5-game-editor --skill implement-runtime-feature
Clone the repo
git clone --depth 1 https://github.com/andvolodko/html5-game-editor

Made for: Claude Code, Codex, Cursor.

Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,564 The whole file, excluding the scripts and references it only reads on demand.
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 $0.00055 $0.01564
Opus 5 $0.00028 $0.00782
Sonnet 5 $0.00011 $0.00313
Haiku 4.5 $0.00006 $0.00156

Measured 2d ago against content hash 76b96875a306, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

implement-runtime-feature 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/skills/implement-runtime-feature/SKILL.md · 121 lines

How it starts

The opening of the file, as written. The whole thing — 121 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Implement Runtime Feature

Counterpart to .cursor/skills/implement-editor-feature/SKILL.md for work that ships in games, not the editor shell.

New Script components (defineComponent + behaviour class): use .cursor/skills/create-game-component/SKILL.md instead — do not duplicate that OOP/catalog checklist here.

New independently buildable game package: .cursor/skills/create-game/SKILL.md.

When to use this skill

  • Gameplay services on GameRuntime / ScriptRuntimeServices (audio, preload, spawn, scene change, pointer forwarding).
  • Runtime scene host behaviour (ScriptHost lifecycle, tick, pause).
  • Shared renderer-agnostic systems in packages/runtime or packages/game-components.
  • Input/audio/timers used by multiple scripts.
  • Scene transitions and asset preload for standalone builds / Preview.

Do not use this for Inspector, docking, undo commands, or project-server routes.

Before changing code

  1. Name the layer. Runtime-safe code must not import:

    • apps/editor, @game-editor/editor-core
    • React
    • apps/project-server
    • Pixi/Three from packages/game-components shared scripts
  2. If the feature is renderer-specific, put it in packages/renderer-pixi or packages/renderer-three. Games that do not use that renderer must not gain a static import (see docs/runtime.md).

  3. Read only docs/runtime.md plus, if needed, docs/renderers.md / docs/scene-model.md. Follow .cursor/rules/core.mdc dependency direction.

  4. Inspect packages/runtime/src/game-runtime.ts and packages/game-components/src/types.ts (ScriptRuntimeServices) before adding a parallel service locator.

Implementation workflow

1. Choose the package

Need Package
Tick, load scene, register renderers, script host packages/runtime (GameRuntime, ScriptHost, load-game-project.ts)
Service API consumed by scripts ScriptRuntimeServices in packages/game-components/src/types.ts; implement on GameRuntime
Audio packages/runtime/src/html-audio-player.ts (HTMLAudioElement; no Pixi)
Pointer forwarding GameRuntime.emitNodeClick / emitNodePointerEvent; editor preview: playback-overlay-pointer.ts
Spawn/clone at runtime (not persisted) script-scene-spawn.ts, script-scene-clone.ts
Scene I/O patches for scripts script-scene-io.ts (transforms, Model3D playback, sprite asset)
Shared behaviour packages/game-components/src/shared/ via create-game-component
Game-specific behaviour games/<name>/src/components/ via create-game-component
Pixi/Three object mapping pixi-runtime-nodes.ts / three-runtime-nodes.ts — never stored on SceneData

Read the full file on GitHub · 121 lines

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 · 121 lines · 55 tokens per session scan A 76b96875a306

Subscribe to this mod's changes

implement-runtime-feature is a skill published in the GitHub repository andvolodko/html5-game-editor (5 stars, last pushed 8d ago), licensed MIT. It adds 55 tokens to every session and 1,564 once invoked, about $0.0003 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.

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