mobile

Guidelines for Hotwire Native, a way to show web pages inside native iOS and Android apps. It covers WebView content, app-like navigation, links, and platform-specific settings.

In plain words
What is it for?
Use them when building or adapting a Rails or other web interface for Hotwire Native. They cover URL-based navigation, in-app browsers, screen replacement, and JSON configuration files.
Why use it?
They help one web application behave consistently on websites and mobile apps. They clarify how links, screens, external pages, and navigation rules should work.

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/levifig/rails-instructions/mobile
Clone the repo
git clone --depth 1 https://github.com/levifig/rails-instructions

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 963 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 $0.00963
Opus 5 $0.00000 $0.00481
Sonnet 5 $0.00000 $0.00193
Haiku 4.5 $0.00000 $0.00096

Measured yesterday against content hash 462c041cbef6, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

mobile 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/rails/mobile.mdc · 134 lines

How it starts

The opening of the file, as written. The whole thing — 134 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Hotwire Native Guidelines

Core Concepts

  • Hotwire Native displays web content in a native shell with platform-specific navigation
  • Web content renders in a WebView with native-feeling transitions and behaviors
  • Link navigation is intercepted and handled by the native adapter
  • Build once for the web, deploy simultaneously to web and native mobile apps
  • Progressively enhance with native components where higher fidelity is needed
  • Design web content to work across web, iOS, and Android
  • Links between pages become native screen transitions automatically
  • External links open in an in-app browser (SFSafariViewController on iOS, Custom Tabs on Android)
  • Use data-turbo-action="replace" to replace the current screen instead of pushing a new one
  • Ensure all screens are accessible via URLs for proper native navigation

Path Configuration

  • Define platform-specific navigation rules in a JSON configuration file
  • Host configuration files at versioned URLs (e.g., /configurations/ios_v1.json)
  • Include both local (bundled) and remote (server-hosted) configurations
  • Use regex patterns to match URLs and apply specific behaviors
  • Configuration example:
{
  "settings": {
    "feature_flags": [
      {
        "name": "enable_new_feature",
        "enabled": true
      }
    ]
  },
  "rules": [
    {
      "patterns": [
        "/modal/.*"
      ],
      "properties": {
        "context": "modal"
      }
    },
    {
      "patterns": [
        "/tabs/.*"
      ],
      "properties": {
        "presentation": "refresh"
      }
    }
  ]
}

Bridge Components

  • Use Bridge Components for web-to-native communication
  • Components have both web (Stimulus) and native (Swift/Kotlin) counterparts
  • Register component handlers in your native app and attach web controllers in HTML
  • Use for native UI elements like top bar buttons, action sheets, and platform APIs
  • Web component implementation example:
// app/javascript/controllers/native_button_controller.js
import { Controller } from "@hotwired/stimulus"
import { BridgeComponent } from "@hotwired/bridge"

export default class extends Controller {
  static values = { title: String, style: String }

  connect() {
    this.bridge = new BridgeComponent("button", this)
    this.bridge.send("connect", {
      title: this.titleValue,
      style: this.styleValue || "default"
    })
  }

  disconnect() {
    this.bridge.send("disconnect")
  }

  handleTap(message) {
    // Handle tap event from native
    const form = this.element.closest("form")
    if (form) form.requestSubmit()
  }
}

Read the full file on GitHub · 134 lines

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 · 134 lines · 963 tokens per session scan A 462c041cbef6

Subscribe to this mod's changes

mobile is a cursor rule published in the GitHub repository levifig/rails-instructions (54 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 963 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.