hayba-room-grammar-prototype

hayba-room-grammar-prototype is a skill for Claude Code, Codex from zajalist/hayba. It costs 29 tokens per session (418 once invoked), scanned A, original, MIT.

A game-development workflow for prototyping repeatable room or set-piece layouts from explicit grammar rules. A grammar is a set of rules that turns starting elements into structured variations.

In plain words
What is it for?
Use it to define one room-generation rule, expand a small set of seeds, reject invalid placement plans, and validate authorized results in an Unreal scene.
Why use it?
It helps explore controlled layout variations while preserving entrances, exits, clearances, object limits, and other constraints. It also distinguishes a rule expansion check from actually placing objects in a game scene.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to define one room-generation rule, expand a small set of seeds, reject invalid placement plans, and validate authorized results in an Unreal scene.

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Install with agentmods
npx agentmods add skills/zajalist/hayba/hayba-room-grammar-prototype
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.

Any agent
npx skills add zajalist/hayba --skill hayba-room-grammar-prototype
Clone the repo
git clone --depth 1 https://github.com/zajalist/hayba

Made for: Claude Code, Codex.

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 hayba-room-grammar-prototype

README.md
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Your own site
<a href="https://agentmods.dev/skills/zajalist/hayba/hayba-room-grammar-prototype"><img src="https://agentmods.dev/badge/skills/zajalist/hayba/hayba-room-grammar-prototype/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.

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Your own site · 80×15
<a href="https://agentmods.dev/skills/zajalist/hayba/hayba-room-grammar-prototype"><img src="https://agentmods.dev/badge/skills/zajalist/hayba/hayba-room-grammar-prototype.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 29 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 418 The whole file, excluding the scripts and references it only reads on demand.
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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00029 $0.00418
Opus 5.5 $0.00012 $0.00167
Sonnet 5.5 $0.00006 $0.00084
Haiku 4.5 $0.00003 $0.00042

Measured 13d ago against content hash d8e700fa6f33, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

hayba-room-grammar-prototype 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 13d 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.

mcp-tools/hayba-mcp/addons/workflows/hayba-room-grammar-prototype/SKILL.md · 25 lines

What it actually says

Prototype one room grammar

When to use

Use for a bounded room family with defined entrance, exit, functional zones, required clearances, and variation count. State the maximum placed objects or instances, repetition tolerance, and platform budget if supplied. Separate fixed hero elements from generated filler before authoring rules.

Tool routing

  • Read plumb_production_list and plumb_constraint_list for existing rules and guards. Use plumb_production_define to add one seed-to-layout rule with explicit emitted shells, assets, or symbols. Call get_tool_signature for the exact rule schema rather than inventing an operation.
  • Expand a small set of seeds with plumb_grammar_expand and inspect every PlacementPlan. Dry-run expansion skips geometry-dependent constraints, so a successful dry run is a syntax and rule-choice check only. Reject plans that violate the stated exit, clearance, instance, or repetition limits before placing them.
  • If the plan is applied to an authorized scene through the project's world authoring path, run plumb_validate on resulting instances and inspect scene_export plus editor_capture_viewport. Resolve hard failures and record soft costs. Route any PCGEx graph implementation through the node-selection and output-audit workflows.
  • If applying the plan changed persistent map content, save the exact active map with level_save, inspect saved, dirty, and verified status, and re-read scene_export for the placed instances. A dry run needs no map save. If persistence is uncertain, mark the placement unsaved and route it to hayba-world-save-integrity.

Evidence

Report rule identifiers, seeds, accepted/rejected variants and reasons, placement counts, validation verdicts, visual captures, and budgets measured. A PlacementPlan is not a spawned room; skipped geometric guards and unloaded-world costs remain unknown until applied and observed.

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. 13d ago First seen · 25 lines · 29 tokens per session scan A d8e700fa6f33

Subscribe to this mod's changes

hayba-room-grammar-prototype is a skill published in the GitHub repository zajalist/hayba (13 stars, last pushed 3d ago), licensed MIT. It adds 29 tokens to every session and 418 once invoked, about $0.0001 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 2026-10-04.

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