create-cursor-rule

name	create-cursor-rule
description	Create or update a Cursor rule in the GeoBrix project. Use when the user wants to add a rule, document a convention, or add file-scoped guidance in .cursor/rules/.

Create a Cursor Rule (GeoBrix)

Use this skill when adding or updating a Cursor rule in this project. For generic rule format and frontmatter, also refer to Cursor’s create-rule skill; this skill adds GeoBrix paths, naming, and integration with the rule system.

Where rules live

• Path: .cursor/rules/ at project root.
• Format: One rule per file, extension .mdc, with YAML frontmatter and markdown body.
• Master rule: 00-agent-context.mdc is the read-first context (topic→subagent, topic→rules). Do not duplicate its role; new rules are topic rules or file-scoped rules that 00-agent-context or subagents can reference.

Naming and role

• Critical / read-first: Use a numeric prefix so it sorts first, e.g. 00-agent-context.mdc, 01-<name>.mdc. Reserve 00- for the single agent-context rule.
• Topic rules: Use a short, kebab-case name that matches the topic, e.g. function-info.mdc, docs-test-single-source.mdc, subagent-protocol.mdc.
• One concern per rule: Keep each rule focused; split broad topics into multiple rules if needed.

Frontmatter (required)

Use YAML at the top of every rule:

---
description: Brief description of what this rule does (one line)
alwaysApply: true | false
globs: "path/pattern"   # Optional; use when rule is file- or path-scoped
---

• alwaysApply: true — Loaded every session. Use sparingly (e.g. 00-agent-context, subagent-protocol, or a small set of global standards). Most rules should be false.
• alwaysApply: false — Rule is loaded when relevant (e.g. matching file open, or referenced by 00-agent-context). Use globs to scope by path, e.g. scripts/**/*.py, docs/tests/python/**/*.py.
• description — Short phrase for the rule; keep it clear and searchable.

Content guidelines

• Concise: Prefer under 50 lines for a single rule; under 500 lines total. If longer, consider splitting.
• Actionable: Write as internal docs: what to do, when, and why. Include concrete examples (good vs bad) where it helps.
• Link, don’t duplicate: Point to 00-agent-context for topic→subagent and topic→rules. Point to subagent files (.cursor/agents/*.md) for domain detail. Avoid copying large blocks from other rules.

After creating or changing a rule

1. Topic → rules table: If the rule defines or refines a topic (e.g. testing, docs, function-info, coverage), add or update that topic’s row in .cursor/rules/00-agent-context.mdc in the “Topic → Rule Files” table so agents know where to find it.
2. Subagent: If the rule belongs to a topic owned by a subagent (see 00-agent-context “Topic → Subagent” table), add a short note in that subagent’s .cursor/agents/<name>.md under a “Rule reference” or “Rules” section, e.g. “See function-info.mdc for generator and testing.”
3. No duplicate topics: If the rule replaces or narrows an existing one, update 00-agent-context (and any references) so the topic points to the right file(s).

Example: New topic rule

Creating a rule for “reader naming”:

1. Add .cursor/rules/reader-naming-convention.mdc with frontmatter (description, alwaysApply: false, and globs if it’s path-scoped, e.g. docs/**/*.md, src/**/*.scala).
2. Write the body (convention, examples, links to code or other rules).
3. In 00-agent-context, under “Topic → Rule Files”, add a row or cell for the topic (e.g. “Naming” or “Readers”) and list reader-naming-convention.mdc.
4. If a subagent owns that topic (e.g. VectorX for vector readers), add a one-line reference in that subagent’s .md.

Checklist

• File is .mdc in .cursor/rules/ with a clear, kebab-case name.
• Frontmatter has description and alwaysApply; globs if path-scoped.
• Content is focused and under ~500 lines; includes examples where useful.
• 00-agent-context “Topic → Rule Files” updated if this is a topic rule.
• Owning subagent’s .md updated with a pointer to the rule, if applicable.

Reference

• Generic rule format: Cursor skill create-rule (frontmatter, globs, examples).
• GeoBrix rule layout: .cursor/rules/00-agent-context.mdc (topic index), .cursor/rules/subagent-protocol.mdc (delegation), .cursor/rules/function-info.mdc (example of a topic rule with globs).