data-rules

A set of Android rules for implementing data classes, which are code structures used to hold app data. It defines naming, field types, annotations, and the expected structure for models representing API responses.

In plain words
What is it for?
Use it when writing or checking Android API data models, including parcelable models passed between Android components.
Why use it?
It reduces inconsistent model code and helps ensure Android models match the fields sent by a server. It also sets clear defaults for optional fields and collections.

Cursor rule for Cursor

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.

agentmods
npx agentmods add rules/heegyeong/composesample/data-rules
Clone the repo
git clone --depth 1 https://github.com/HeeGyeong/ComposeSample

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 352 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00000 $0.00352
Opus 5 $0.00000 $0.00176
Sonnet 5 $0.00000 $0.00070
Haiku 4.5 $0.00000 $0.00035

Measured yesterday against content hash 01c2d5624cab, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

data-rules 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 yesterday.

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.

.cursor/rules/data-rules.mdc · 58 lines

What it actually says


description: "Data Class Implementation Rules for Android Development" globs: "" alwaysApply: true

Data Class Implementation Rules

Overview

This rule defines the implementation guidelines for data classes in the Android project. Follow the comprehensive guidelines from DataRules.md.

Key Rules

Naming Conventions

  • File Pattern: {Domain}Data.kt or {Domain}ListData.kt
  • Server fields: snake_case
  • Client fields: camelCase
  • Boolean flags: prefix with 'is' or 'has'
  • YN flags: String type with "Y"/"N"

Required Structure

@Parcelize
data class ExampleData(
    @SerializedName("server_field")
    val clientField: Type? = defaultValue
) : Parcelable

Mandatory Annotations

  • @SerializedName: REQUIRED for all API response fields
  • @Parcelize: REQUIRED for Android component data transfer

Field Types

  • Required fields: Non-null types
  • Optional fields: Nullable types with defaults
  • Collections: Empty collection defaults

Companion Objects

companion object {
    val EMPTY = DataModel("")
    val MOCK = DataModel("test_data")
}

Validation Requirements

  1. ALL fields must have @SerializedName
  2. Field names must match API spec exactly
  3. Default values for nullable fields
  4. Proper nullability handling
  5. Documentation for complex business logic
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. yesterday First seen · 58 lines · 0 tokens per session scan A 01c2d5624cab

Subscribe to this mod's changes

data-rules is a cursor rule published in the GitHub repository HeeGyeong/ComposeSample (11 stars, last pushed yesterday), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 352 tokens. 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.