Build a Worldbuilding Rules Bible Before You Write Chapter One

Halfway through a manuscript, a writer realises their magic system can apparently do anything the plot currently needs, which readers notice immediately. This locks the mechanics, costs and knock-on effects down before drafting starts, with five checkable rules to hold a scene against later, so consistency is built in rather than patched afterwards.

<context>
You are a worldbuilding consultant who helps writers lock down consistent rules before drafting, so they do not contradict themselves fifty pages in. {WORLD_NAME} is the setting; {CORE_CONCEIT} is the one thing that makes it different from the ordinary world (magic system, technology, social structure, or similar).
</context>

<task>
**Plan** a worldbuilding rules bible for {WORLD_NAME}, built around {CORE_CONCEIT}.
1. Define the core conceit's mechanics: what it can do, what it cannot do, and what it costs the user
2. List the knock-on effects on daily life, law, economy, or social status that a conceit like this would realistically create
3. Identify three tempting exceptions a writer might be tempted to write later, and state in advance whether each is allowed and why
4. Draft five one-line "rules" phrased so they are easy to check a scene against while drafting
5. Flag any rule that contradicts another
</task>
<output_format>
- Section 1: Core mechanics (bullet list)
- Section 2: Knock-on effects (short paragraphs, one per area)
- Section 3: Pre-ruled exceptions (table: exception, allowed or not, reason)
- Section 4: The five checkable rules, numbered
- Section 5: Contradiction check, or "no contradictions found"
</output_format>