# CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

## Build & Test Commands

Use the **Xcode MCP server** tools instead of `xcodebuild` CLI:

- **List windows first**: Always run `mcp__xcode__XcodeListWindows` to find the correct `tabIdentifier` — it changes depending on which Xcode windows are open.
- **Build**: `mcp__xcode__BuildProject`
- **Run all tests**: `mcp__xcode__RunAllTests`
- **Check errors**: `mcp__xcode__GetBuildLog` (severity: `error`) or `mcp__xcode__XcodeListNavigatorIssues`

No external dependencies beyond the Xcode toolchain.

## Architecture

**SwiftUI + SwiftData app** for sizing low-voltage electrical conductors (boats, RVs, off-grid).

### Data Model Hierarchy

`ElectricalSystem` is the top-level container. Child entities reference their parent via an optional `system: ElectricalSystem?` property:
- `SavedLoad` — individual electrical loads with wire sizing parameters
- `SavedBattery` — battery banks with chemistry-specific capacity rules
- `SavedCharger` — charging equipment specs

All are `@Model` classes persisted via SwiftData. The container is configured in `CableApp.swift` and injected into the SwiftUI environment.

### Key Layers

- **Calculation engine** (`Loads/ElectricalCalculations.swift`): Pure static functions for wire cross-section sizing, voltage drop, power loss, and fuse recommendations. Uses copper resistivity (0.017 Ω·mm²/m) with a 5% max voltage drop constraint. Supports both metric (mm²) and imperial (AWG) wire standards.
- **CableCalculator** (`Loads/CableCalculator.swift`): ObservableObject wrapper that bridges the calculation engine to SwiftUI views. Instantiated per-view as `@StateObject`, not globally injected.
- **App-wide state**: `UnitSystemSettings` (metric/imperial, persisted to UserDefaults) is injected as `@EnvironmentObject`.

### Navigation Flow

`SystemsView` (root list) → `LoadsView` (per-system TabView with 4 tabs: Overview, Components, Batteries, Chargers) → individual editor modals for each entity type.

### Feature Organization

Each feature has its own directory under `Cable/`: `Loads/`, `Systems/`, `Batteries/`, `Chargers/`, `Overview/`, `Shared/`. Models and views for each feature live together.

### SwiftData Query Pattern

`@Query` fetches all records globally, then a computed property filters by system relationship — SwiftData doesn't efficiently handle relationship-based predicates in `@Query`:
```swift
@Query(sort: \SavedLoad.timestamp, order: .reverse) private var allLoads: [SavedLoad]
private var savedLoads: [SavedLoad] { allLoads.filter { $0.system == system } }
```

### Unit Storage Convention

All values are stored in **metric** (meters, mm²). Conversion to imperial (feet, AWG) happens **at display time only**, never at storage time. `UnitSystemSettings.unitSystem` drives the display format.

## UI Patterns

### Editor Pattern (Battery, Charger, Load)

All editors follow the same architecture:
1. **Configuration struct** (e.g. `BatteryConfiguration`, `ChargerConfiguration`) as a transient draft — not an `@Model`. Has dual inits: one for new items, one from an existing `Saved*` model.
2. **Alert-based field editing**: Each numeric field gets its own `.alert()` with a `TextField`, bound via an `EditingField` enum. `onChange` updates the configuration live as the user types.
3. **Snap-to-values**: Common electrical values (12V, 24V, 48V, 230V, etc.) snap within a tolerance when the field is not actively being edited.
4. **Save flow**: `onSave: (Configuration) -> Void` callback to the parent view. `onDisappear` triggers save automatically. Parent calls `SystemComponentsPersistence` to persist.
5. **Appearance modal**: All editors include a `.sheet` presenting `ItemEditorView` for name/icon/color editing.

Navigation to editors uses `.navigationDestination(item: $draft)` where `$draft` is a `@State` optional Configuration.

### Shared UI Components

- **`ItemEditorView`** (`ItemEditorView.swift`): Shared appearance editor for name, icon (5-column SF Symbol grid), and color (6-column grid). Uses `AutoSelectTextField` for auto-focus. Accepts optional `additionalFields` builder.
- **`StatsHeaderContainer`** (`StatsHeaderContainer.swift`): Header card with scrollable metric pills. Uses `glassEffect` on iOS 26+, fallback with colored background + border.
- **`OnboardingInfoView`** (`Loads/OnboardingInfoView.swift`): Empty state with auto-rotating image carousel (8s interval). Configured via static factory methods: `.loads()`, `.battery()`, `.charger()`.
- **`LoadIconView`** (`Loads/LoadIconView.swift`): Component icon with remote URL support and `IconCache` (memory + file-based). Also exports `ComponentSummaryMetricView` and `ComponentMetricBadgeView`.

### List Styling Convention

All list views use consistent styling:
- `.listStyle(.plain)`, `.scrollContentBackground(.hidden)`, `.scrollIndicators(.hidden)`
- `.listRowSeparator(.hidden)`, `.listRowBackground(Color.clear)`
- Row cards: `RoundedRectangle(cornerRadius: 18, style: .continuous).fill(Color(.systemBackground))` with 16pt padding
- Headers via `.safeAreaInset(edge: .top)` containing `StatsHeaderContainer`

### Color Convention

`Color.componentColor(named:)` (in `LoadIconView.swift`) maps string names to SwiftUI colors (13 options: blue, green, orange, red, purple, yellow, pink, teal, indigo, mint, cyan, brown, gray). Used for all component icons. Badge backgrounds use `tint.opacity(0.12)`.

## Analytics

`AnalyticsTracker.log(_:properties:)` wraps Aptabase. Tracks: create, edit, update, delete, tab changes, navigation. In DEBUG builds, prints to NSLog.

## Component Library

`ComponentLibraryViewModel` fetches from a **PocketBase** backend with paginated API calls. Items have multi-language translations and locale-aware affiliate links (exact region match → language-only fallback → global fallback). Use `ComponentLibraryViewModel(previewItems:)` to bypass network in previews.

## Code Style

- 4-space indentation, trailing commas on multiline collections, 120-char soft line limit
- `UpperCamelCase` for types, `lowerCamelCase` for methods/properties
- Test naming: `testScenario_expectedResult`
- Commit messages: short imperative subjects under 50 characters

## Localization

5 languages: English (base), German, Spanish, French, Dutch. Translation files are in `*.lproj/Localizable.strings` and `Localizable.stringsdict`.

- Use `String(localized:defaultValue:)` — **not** `NSLocalizedString`. The `defaultValue` serves as English fallback and avoids showing raw keys when a Localizable.strings entry is missing.
- When adding new user-facing strings, add translations to **all 5** Localizable.strings files immediately.

## PDF Export Pattern

PDF exports use `UIGraphicsPDFRenderer` with A4 portrait format. The pattern is:
- **Exporter struct** (e.g. `SystemOverviewPDFExporter`, `SystemBillOfMaterialsPDFExporter`) with snapshot data types — keeps Core Graphics rendering isolated from SwiftUI/SwiftData.
- **ShareSheet** triggered via `@State` item binding in the parent view.
- **Toolbar button** (not inline content) for the export action.

## Screenshots & Previews

Screenshot previews for all major views live in `Cable/ScreenshotPreviews.swift`. This file contains wrapper views and realistic sample data so screenshots include full app chrome (NavigationBar, TabBar).

### How to render screenshots

1. Use `mcp__xcode__RenderPreview` with `sourceFilePath: "Cable/ScreenshotPreviews.swift"` and `previewDefinitionIndexInFile` (0–44, grouped by view × 5 languages).
2. Output goes to `Shots/Screenshots/`.

### Preview index mapping

Previews are grouped in blocks of 5 (EN, DE, ES, FR, NL):
- 0–4: Overview tab
- 5–9: Components tab
- 10–14: Batteries tab
- 15–19: Chargers tab
- 20–24: Systems list
- 25–29: Parts Library
- 30–34: Load editor (CalculatorView)
- 35–39: Battery editor
- 40–44: Charger editor

### Key patterns for preview-friendly views

- **LoadsView** accepts an `initialTab` parameter (`LoadsView.ComponentTab`) to control which tab is shown. Wrap in `NavigationStack` to get the navigation bar.
- **ComponentLibraryView** accepts an optional `viewModel` parameter via `init(viewModel:onSelect:)`. Use `ComponentLibraryViewModel(previewItems:)` to inject mock data and avoid network dependency.
- All preview wrappers inject `.modelContainer(container)` (in-memory) and `.environmentObject(UnitSystemSettings())`.

### Localization limitation

`.environment(\.locale, Locale(identifier: "xx"))` does **not** affect `String(localized:defaultValue:)` — those resolve from the app bundle, not the SwiftUI environment. All preview screenshots render in the system language. For multi-language screenshots, use UI tests with `-AppleLanguages` launch arguments or change the Xcode scheme language.

## Model Definitions

SwiftData `@Model` classes live in their feature directories: `ElectricalSystem` and `SavedLoad` in `Loads/CableCalculator.swift`, `SavedBattery` in `Batteries/SavedBattery.swift`, `SavedCharger` in `Chargers/SavedCharger.swift`. `Item.swift` is a legacy model.

## Xcode Project Structure

The project uses **automatic file inclusion** — no explicit file references in `project.pbxproj` for Swift sources. New `.swift` files in the `Cable/` directory are picked up automatically.

## Dependencies

- **SPM**: `aptabase-swift` (analytics) — referenced in `project.pbxproj`, resolved automatically by Xcode.
- **CocoaPods**: `Podfile` exists but has no pods listed — effectively unused.
- `Package.resolved` is in `xcshareddata` which is gitignored — it will be regenerated on a fresh checkout.

## SourceKit Diagnostics

SourceKit may show false-positive errors (e.g. "Cannot find type in scope") while the project builds successfully. These are indexing artifacts — always verify with an actual build via `mcp__xcode__BuildProject`.