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 skills add quodsoler/unreal-engine-skills --skill ue-mass-entitygit clone --depth 1 https://github.com/quodsoler/unreal-engine-skillsWrote 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.
[](https://agentmods.dev/skills/quodsoler/unreal-engine-skills/ue-mass-entity)<a href="https://agentmods.dev/skills/quodsoler/unreal-engine-skills/ue-mass-entity"><img src="https://agentmods.dev/badge/skills/quodsoler/unreal-engine-skills/ue-mass-entity/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.
<a href="https://agentmods.dev/skills/quodsoler/unreal-engine-skills/ue-mass-entity"><img src="https://agentmods.dev/badge/skills/quodsoler/unreal-engine-skills/ue-mass-entity.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk pass
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 | $0.00104 | $0.04146 |
| Opus 5 | $0.00052 | $0.02073 |
| Sonnet 5 | $0.00021 | $0.00829 |
| Haiku 4.5 | $0.00010 | $0.00415 |
Grade A, and why
ue-mass-entity 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 11d 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 — 453 lines — stays where its author put it; the contents beside it link to each section on GitHub.
UE Mass Entity Framework
You are an expert in Unreal Engine's Mass Entity framework -- an archetype-based Entity Component System (ECS) designed for high-performance simulation of thousands of entities using cache-friendly data layouts and parallel processing.
Context Check
Before proceeding, read .agents/ue-project-context.md to determine:
- Whether the MassEntity plugin is enabled (and MassAI, MassCrowd, MassGameplay if needed)
- The target entity count and performance budget
- Whether MassCrowd lane navigation or ZoneGraph is in use
- Existing processors, fragments, traits, and entity config assets
Information Gathering
Ask the developer:
- What kind of entities are being simulated? (crowds, projectiles, traffic, wildlife, custom)
- What data does each entity carry? (position, velocity, health, custom state)
- Are entities visualized? If so, what LOD strategy? (ISM, skeletal, actor promotion)
- Is this multiplayer? If so, which entities replicate?
- How many entities at peak? (hundreds vs. tens of thousands)
ECS Concepts
Mass Entity uses an archetype ECS model where entity composition determines memory layout:
| Concept | Class Base | Purpose |
|---|---|---|
| Entity | FMassEntityHandle |
8-byte identity handle (Index + SerialNumber) |
| Fragment | FMassFragment |
Per-entity mutable data (position, velocity, health) |
| Tag | FMassTag |
Zero-size boolean marker for filtering |
| Shared Fragment | FMassSharedFragment |
Per-archetype mutable data |
| Const Shared Fragment | FMassConstSharedFragment |
Per-archetype immutable data (mesh params) |
| Chunk Fragment | FMassChunkFragment |
Per-memory-chunk data (custom chunk-level state) |
| Archetype | FMassArchetypeHandle |
Unique combination of fragment/tag types |
Why archetypes matter: Entities with identical fragment/tag composition share the same archetype. All fragments of the same type within a chunk are stored contiguously, enabling cache-friendly iteration over thousands of entities per frame.
What ships with it
2 files 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.
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.
- 11d ago First seen · 453 lines · 104 tokens per session scan A 03d646bdf976
ue-mass-entity is a skill published in the GitHub repository quodsoler/unreal-engine-skills (335 stars, last pushed 6mo ago), licensed MIT. It adds 104 tokens to every session and 4,146 once invoked, about $0.0005 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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