What is prefab-sentinel AGENTS.md?

A repository guide for AI coding agents working on prefab-sentinel. It defines project rules, design principles, document ownership, and required change procedures.

Following repository conventions, deciding which files or documents to change, checking responsibility boundaries, and enforcing fail-fast and verification rules.

It reduces guesswork about how the project is organized and how changes must be made. It also requires related technical documentation to stay updated.

How tyunta/prefab-sentinel configures Codex and OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to tyunta/prefab-sentinel. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/tyunta/prefab-sentinel/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/tyunta/prefab-sentinel

Made for: Codex, OpenCode.

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/tyunta/prefab-sentinel/agents-md/github.svg)](https://agentmods.dev/instructions/tyunta/prefab-sentinel/agents-md)

Your own site

<a href="https://agentmods.dev/instructions/tyunta/prefab-sentinel/agents-md"><img src="https://agentmods.dev/badge/instructions/tyunta/prefab-sentinel/agents-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/tyunta/prefab-sentinel/agents-md"><img src="https://agentmods.dev/badge/instructions/tyunta/prefab-sentinel/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 4,991 This file is loaded in full into every session.

When invoked 4,991 The same file — it is already loaded in full.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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.

Model	Per session	Once invoked
Fable 5.1	$0.04991	$0.04991
Opus 5.5	$0.01996	$0.01996
Sonnet 5.5	$0.00998	$0.00998
Haiku 4.5	$0.00499	$0.00499

Measured 1mo ago against content hash a501882d27c7, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

prefab-sentinel 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 1mo 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.

AGENTS.md · 131 lines

How it starts

The opening of the file, as written. The whole thing — 131 lines — stays where its author put it; the contents beside it link to each section on GitHub.

プロジェクト運用ルール

AI agent 初回参照: AGENT_GUIDE.md

本ファイルは prefab-sentinel リポジトリの運用ルール正本。仕様の正本は専門ドキュメント（docs/api-reference.md / docs/tool-conventions.md / docs/execution-reference.md / ARCHITECTURE.md / TESTING.md / CONFIGURATION.md）に分かれて置かれ、README.md はそれらへの入口（エントリポイント兼ルーター）として機能する。仕様に関わる変更を行う場合は、実装変更と同時に対応する専門ドキュメントの該当箇所を更新する。

設計原則

Easy より Simple: 目的達成に必要な最小実装を優先する。
根拠優先: 前提・不変条件・判断理由を明文化する。
検証可能性: 設定値と結果の対応を説明できる実装のみ採用する。
必須参照の欠落は補完せず error で停止する（fail-fast）。
ファイルサイズ目安（200〜400 行）は partial 単位で評価する。1 ファイル合計ではなく partial class ごとの責務単位で行数を判定する。partial 構成は disk 上のファイル名（tools/unity/PrefabSentinel.Unity*Bridge.<Concern>.cs）が正本で、test が AGENTS.md inventory との drift を検出する（tests/test_editor_control_bridge_source.py::TestOperationalRulesPartialInventory / tests/test_unity_patch_bridge_source.py::TestPatchBridgeOperationalRulesInventory）。
現在の per-concern token inventory（test 用、追加・削除時に同期）:
- UnityEditorControlBridge: Acceptance / AnimationClip / AssetDelete / AssetOps / AssetOps.Create / AssetOps.Move / BlendShape / BridgeDeploy / CameraView / CompileBarrier / Components / ConsoleCapture / EditorState / Geometry / GeometryContributors / Helpers / Hierarchy / InspectorSurface / InspectorSurface.Payload / InspectorSurface.Scene / MaterialBatch / MaterialQuery / MaterialWrite / Menu / MenuScriptWatch / PrefabStage / Properties / PropertyObjectReference / PropertyWrite / RendererFramingBounds / RunScriptAsync / RunScriptCompile / SaveInstantiate / Screenshot / Screenshot.TargetCapture / Screenshot.TargetCapture.WorldSpaceUi / SerializedProperty / SerializedProperty.ObjectReference / SerializedProperty.Payload / SerializedProperty.Target / SerializedProperty.Traversal / SerializedProperty.Write / UdonSharpAddComponent / UdonSharpArrayWrite / UdonSharpFieldWrite / UdonSharpInvocation / UdonSharpListenerWiring / UiElement
- UnityPatchBridge: Payloads / Prefab / OpenComposition / OpenCompositionAudit / Asset / Scene / Resolve / Mutation / ManagedReference / Diagnostics
Mutation partial は value-kind dispatcher と各 SerializedPropertyType 用 reader が 1 つの cohesive concern を構成するため、200〜400 行ガイドラインも issue #129 暫定の 1,000 行上限も意図的に超過する（issue #129 spec.md "further sub-split" / Non-Goals 参照）。

Read the full file on GitHub · 131 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.

1mo ago Changed · +9 tokens per session a501882d27c7
2mo ago First seen · 131 lines · 4,982 tokens per session scan A dcb46d8cbc60

Subscribe to this mod's changes

prefab-sentinel AGENTS.md is an instructions file published in the GitHub repository tyunta/prefab-sentinel (12 stars, last pushed 1mo ago), licensed MIT. It adds 4,991 tokens to every session, about $0.0200 per session on Opus 5.5. 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.

prefab-sentinel AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
prefab-sentinel AGENTS.mdtyunta/prefab-sentinel	Instructions file	12	1mo ago	MIT	A	4,991	Codex, OpenCode
vscode buildNext.instructions.mdmicrosoft/vscode	Instructions file	195k	today	MIT	A	9,719	GitHub Copilot
next.js AGENTS.mdvercel/next.js	Instructions file	143k	today	MIT	A	7,461	Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscode	Instructions file	195k	today	MIT	A	5,516	GitHub Copilot
langchain AGENTS.mdlangchain-ai/langchain	Instructions file	149k	today	MIT	A	4,680	Codex, OpenCode
vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	today	MIT	A	3,093	GitHub Copilot
vscode ai-customization.instructions.mdmicrosoft/vscode	Instructions file	195k	today	MIT	A	1,907	GitHub Copilot

prefab-sentinel: Instructions file for Codex