unity-yaml-editing-guide

unity-yaml-editing-guide is a skill for Claude Code, Codex from nowsprinting/unity-coding-skills. It costs 113 tokens per session (1,475 once invoked), scanned A, original, Unlicense.

A guide for editing certain Unity asset files stored in YAML, a text format used to represent structured data. It covers simple ScriptableObject and Material files, but not scenes, prefabs or complex binary-derived assets.

In plain words
What is it for?
Use it when directly editing allowed .asset or .mat files, while preserving Unity’s required headers, document markers and asset references.
Why use it?
It reduces the risk of corrupting Unity projects when changing supported assets outside the Unity Editor. It also explains which files must be left to Unity.

Skill for Claude CodeCodex

Part of the unity-coding-skills plugin — 10 skills, 3 agents shipped together

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/nowsprinting/unity-coding-skills/unity-yaml-editing-guide
Any agent
npx skills add nowsprinting/unity-coding-skills --skill unity-yaml-editing-guide
Clone the repo
git clone --depth 1 https://github.com/nowsprinting/unity-coding-skills

Made for: Claude Code, Codex.

Or install unity-coding-skills, the plugin that ships this one along with the rest of its 10 skills, 3 agents.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for unity-yaml-editing-guide

README.md
[![agentmods](https://agentmods.dev/badge/skills/nowsprinting/unity-coding-skills/unity-yaml-editing-guide.svg)](https://agentmods.dev/skills/nowsprinting/unity-coding-skills/unity-yaml-editing-guide)
Your own site
<a href="https://agentmods.dev/skills/nowsprinting/unity-coding-skills/unity-yaml-editing-guide"><img src="https://agentmods.dev/badge/skills/nowsprinting/unity-coding-skills/unity-yaml-editing-guide.svg" alt="Measured on agentmods" height="20"></a>
Per session 113 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,475 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 $0.00113 $0.01475
Opus 5 $0.00056 $0.00737
Sonnet 5 $0.00023 $0.00295
Haiku 4.5 $0.00011 $0.00147

Measured 4d ago against content hash 5a35580e58b0, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

unity-yaml-editing-guide 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 4d 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.

skills/unity-yaml-editing-guide/SKILL.md · 60 lines

How it starts

The opening of the file, as written. The whole thing — 60 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Guide for directly editing Unity YAML-serialized asset files for Unity projects.

Rules

  • Edit only the following allowlist of simple YAML asset types. Other YAML assets (AnimationClip, AnimatorController, Texture2D, Mesh, AudioClip, LightingDataAsset, etc.) carry binary-derived data or complex internal structure — open them in Unity Editor instead.
    • ScriptableObject (MonoBehaviour, class ID 114) — files *.asset
    • Material (Material, class ID 21) — files *.mat
  • Never directly edit .unity or .prefab files. Use edit-scene skill — those carry GameObject/Prefab-instance structure that is unsafe to author by hand.
  • Never touch .meta files. Unity owns .meta content (GUIDs, importer settings); hand-edits corrupt asset references project-wide.
  • Preserve the mandatory two-line header exactly. Lines 1–2 must be %YAML 1.1 and %TAG !u! tag:unity3d.com,2011: — these are not stylistic, and Unity will fail to load the asset if they drift.
  • Preserve the document marker. --- !u!<classID> &<fileID> — for ScriptableObject use --- !u!114 &11400000, for Material use --- !u!21 &2100000 (canonical local anchors).
  • Keep the canonical preamble field order at the top of the mapping. For ScriptableObject (MonoBehaviour:), the order is m_ObjectHideFlagsm_CorrespondingSourceObjectm_PrefabInstancem_PrefabAssetm_GameObjectm_Enabledm_EditorHideFlagsm_Scriptm_Namem_EditorClassIdentifier. User fields come after.
  • Keep m_Name in sync with the filename (without the .asset / .mat extension) — a mismatch confuses Unity's importer and Resources.Load-style lookups.
  • Cross-file object references need all three keys{fileID: N, guid: <32-hex>, type: T} where type: 2 is a project asset and type: 3 is a script. Local references use {fileID: N} matching an &N anchor in the same file; {fileID: 0} means null.
  • Quote strings only when they contain non-ASCII characters, and escape every non-ASCII code point as \uXXXX inside double quotes — plain ASCII stays unquoted. Match how Unity itself emits the file.
  • Use 2-space indent, LF line endings, UTF-8 without BOM, and a trailing newline at EOF. Tabs, CRLF, or a BOM round-trip badly when Unity re-saves the file.
  • Do not add comments, YAML aliases (*name), extra tags, or chomping indicators (|, >). Unity's YAML parser drops or rejects them, and re-save would strip cosmetic formatting anyway — don't bother polishing what Unity will normalize.
  • After editing, let Unity re-import the asset (focus the Editor) and confirm successful import using get_unity_compilation_result. Review the diff Unity produces on next save to confirm the edit was accepted as intended.

Read the full file on GitHub · 60 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 4d ago First seen · 60 lines · 113 tokens per session scan A 5a35580e58b0

Subscribe to this mod's changes

unity-yaml-editing-guide is a skill published in the GitHub repository nowsprinting/unity-coding-skills (19 stars, last pushed 4d ago), licensed Unlicense. It adds 113 tokens to every session and 1,475 once invoked, about $0.0006 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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