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+applyTo: '**'
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+
+# Copilot instructions (English — concise)
+
+Purpose: provide short, actionable guidance so Copilot suggestions match project conventions.
+
+## Common Development Commands
+
+### Development Server
+- `bin/dev` - Start development server (Rails, Sidekiq, Tailwind CSS watcher)
+- `bin/rails server` - Start Rails server only
+- `bin/rails console` - Open Rails console
+
+### Testing
+- `bin/rails test` - Run all tests
+- `bin/rails test:db` - Run tests with database reset
+- `bin/rails test:system` - Run system tests only (use sparingly - they take longer)
+- `bin/rails test test/models/account_test.rb` - Run specific test file
+- `bin/rails test test/models/account_test.rb:42` - Run specific test at line
+
+### Linting & Formatting
+- `bin/rubocop` - Run Ruby linter
+- `npm run lint` - Check JavaScript/TypeScript code
+- `npm run lint:fix` - Fix JavaScript/TypeScript issues
+- `npm run format` - Format JavaScript/TypeScript code
+- `bin/brakeman` - Run security analysis
+
+### Database
+- `bin/rails db:prepare` - Create and migrate database
+- `bin/rails db:migrate` - Run pending migrations
+- `bin/rails db:rollback` - Rollback last migration
+- `bin/rails db:seed` - Load seed data
+
+### Setup
+- `bin/setup` - Initial project setup (installs dependencies, prepares database)
+
+## Pre-PR workflow (run locally before opening PR)
+- Tests: bin/rails test (all), bin/rails test:system (when applicable)
+- Linters: bin/rubocop -f github -a; bundle exec erb_lint ./app/**/*.erb -a
+- Security: bin/brakeman --no-pager
+
+## High-Level Architecture
+
+### Application Modes
+The app runs in two modes:
+- **Managed** (Rails.application.config.app_mode = "managed")
+- **Self-hosted** (Rails.application.config.app_mode = "self_hosted")
+
+### Core Domain Model
+The application is built around financial data management with these key relationships:
+- **User** → has many **Accounts** → has many **Transactions**
+- **Account** types: checking, savings, credit cards, investments, crypto, loans, properties
+- **Transaction** → belongs to **Category**, can have **Tags** and **Rules**
+- **Investment accounts** → have **Holdings** → track **Securities** via **Trades**
+
+### API Architecture
+The application provides both internal and external APIs:
+- Internal API: Controllers serve JSON via Turbo for SPA-like interactions
+- External API: `/api/v1/` namespace with Doorkeeper OAuth and API key authentication
+- API responses use Jbuilder templates for JSON rendering.
+- Rate limiting via Rack::Attack with configurable limits per API key
+
+### Sync & Import System
+Two primary data ingestion methods:
+1. **Plaid Integration**: Real-time bank account syncing
+ - `PlaidItem` manages connections
+ - `Sync` tracks sync operations
+ - Background jobs handle data updates
+2. **CSV Import**: Manual data import with mapping
+ - `Import` manages import sessions
+ - Supports transaction and balance imports
+ - Custom field mapping with transformation rules
+
+### Background Processing
+Sidekiq handles asynchronous tasks:
+- Account syncing (`SyncJob`)
+- Import processing (`ImportJob`)
+- AI chat responses (`AssistantResponseJob`)
+- Scheduled maintenance via sidekiq-cron
+
+### Frontend Architecture
+- **Hotwire Stack**: Turbo + Stimulus for reactive UI without heavy JavaScript
+- **ViewComponents**: Reusable UI components in `app/components/`
+- **Stimulus Controllers**: Handle interactivity, organized alongside components
+- **Charts**: D3.js for financial visualizations (time series, donut, sankey)
+- **Styling**: Tailwind CSS v4.x with custom design system
+ - Design system defined in `app/assets/tailwind/maybe-design-system.css`
+ - Always use functional tokens (e.g., `text-primary` not `text-white`)
+ - Prefer semantic HTML elements over JS components
+ - Use `icon` helper for icons, never `lucide_icon` directly
+
+### Multi-Currency Support
+- All monetary values stored in base currency (user's primary currency)
+- `Money` objects handle currency conversion and formatting
+- Historical exchange rates for accurate reporting
+
+### Security & Authentication
+- Session-based auth for web users
+- API authentication via:
+ - OAuth2 (Doorkeeper) for third-party apps
+ - API keys with JWT tokens for direct API access
+- Scoped permissions system for API access
+- Strong parameters and CSRF protection throughout
+
+## Key rules
+- Project modes: "managed" or "self_hosted".
+- Domain: User → Accounts → Transactions. Keep business logic in models, controllers thin.
+
+Authentication & context
+- Use Current.user and Current.family (never current_user / current_family).
+
+Testing conventions
+- Use Minitest + fixtures (no RSpec, no FactoryBot).
+- Use mocha for mocks where needed; VCR for external API tests.
+
+Frontend conventions
+- Hotwire-first: Turbo + Stimulus.
+- Prefer semantic HTML, Turbo Frames, server-side formatting.
+- Use the helper icon for icons (do not use lucide_icon directly).
+- Use Tailwind design tokens (text-primary, bg-container, etc.).
+
+Backend & architecture
+- Skinny controllers, fat models.
+- Prefer built-in Rails patterns; add dependencies only with strong justification.
+- Sidekiq for background jobs (e.g., SyncJob, ImportJob, AssistantResponseJob).
+
+API & security
+- External API under /api/v1 with Doorkeeper / API keys; respect CSRF and strong params.
+- Follow rate limits and auth strategies already in project.
+
+Stimulus & components
+- Keep controllers small (< 7 targets); pass data via data-*-value.
+- Prefer ViewComponents for reusable or complex UI.
+
+## Component Architecture
+
+### ViewComponent vs Partials Decision Making
+
+**Use ViewComponents when:**
+- Element has complex logic or styling patterns
+- Element will be reused across multiple views/contexts
+- Element needs structured styling with variants/sizes
+- Element requires interactive behavior or Stimulus controllers
+- Element has configurable slots or complex APIs
+- Element needs accessibility features or ARIA support
+
+**Use Partials when:**
+- Element is primarily static HTML with minimal logic
+- Element is used in only one or few specific contexts
+- Element is simple template content
+- Element doesn't need variants, sizes, or complex configuration
+- Element is more about content organization than reusable functionality
+
+**Component Guidelines:**
+- Prefer components over partials when available
+- Keep domain logic OUT of view templates
+- Logic belongs in component files, not template files
+
+### Stimulus Controller Guidelines
+
+**Declarative Actions (Required):**
+```erb
+
+
+```
+
+**Controller Best Practices:**
+- Keep controllers lightweight and simple (< 7 targets)
+- Use private methods and expose clear public API
+- Single responsibility or highly related responsibilities
+- Component controllers stay in component directory, global controllers in `app/javascript/controllers/`
+- Pass data via `data-*-value` attributes, not inline JavaScript
+
+## Testing Philosophy
+
+### General Testing Rules
+- **ALWAYS use Minitest + fixtures + Mocha** (NEVER RSpec or FactoryBot)
+- Keep fixtures minimal (2-3 per model for base cases)
+- Create edge cases on-the-fly within test context
+- Use Rails helpers for large fixture creation needs
+
+### Test Quality Guidelines
+- **Write minimal, effective tests** - system tests sparingly
+- **Only test critical and important code paths**
+- **Test boundaries correctly:**
+ - Commands: test they were called with correct params
+ - Queries: test output
+ - Don't test implementation details of other classes
+
+### Testing Examples
+
+```ruby
+# GOOD - Testing critical domain business logic
+test "syncs balances" do
+ Holding::Syncer.any_instance.expects(:sync_holdings).returns([]).once
+ assert_difference "@account.balances.count", 2 do
+ Balance::Syncer.new(@account, strategy: :forward).sync_balances
+ end
+end
+
+# BAD - Testing ActiveRecord functionality
+test "saves balance" do
+ balance_record = Balance.new(balance: 100, currency: "USD")
+ assert balance_record.save
+end
+```
+
+### Stubs and Mocks
+- Use `mocha` gem
+- Prefer `OpenStruct` for mock instances
+- Only mock what's necessary
+
+## Performance Considerations
+- Database queries optimized with proper indexes
+- N+1 queries prevented via includes/joins
+- Background jobs for heavy operations
+- Caching strategies for expensive calculations
+- Turbo Frames for partial page updates
+
+## Development Workflow
+- Feature branches merged to `main`
+- Docker support for consistent environments
+- Environment variables via `.env` files
+- Lookbook for component development (`/design-system`)
+- Letter Opener for email preview in development
+
+## Project Conventions
+
+### Convention 1: Minimize Dependencies
+- Push Rails to its limits before adding new dependencies
+- Strong technical/business reason required for new dependencies
+- Favor old and reliable over new and flashy
+
+### Convention 2: Skinny Controllers, Fat Models
+- Business logic in `app/models/` folder, avoid `app/services/`
+- Use Rails concerns and POROs for organization
+- Models should answer questions about themselves: `account.balance_series` not `AccountSeries.new(account).call`
+
+### Convention 3: Hotwire-First Frontend
+- **Native HTML preferred over JS components**
+ - Use `