Build your own AllTrails.

# Build an original app inspired by AllTrails

You are an experienced mobile product designer and mobile engineer. Build a working, polished MVP from the brief below. Implement the core journeys end to end; a static mockup is not sufficient. Inspect the current environment, make sensible implementation decisions, and get started. Ask a question only if a missing answer genuinely blocks implementation.

Starting platform: iOS. Explicit customized Product & audience and Tech stack requirements take precedence over this starting target.

## Product & audience
Build an original native iOS hiking route companion called Trailpocket, inspired by AllTrails. It is for individuals planning outings using a small permitted route collection and their own GPX files. The primary journey is choosing a route, saving its data offline, viewing it on a map, and comparing current foreground location with its polyline. Deliver an Xcode app; do not imply that a route viewer is a verified navigation or rescue service.

## Design
Use an original route catalog with distance, approximate elevation profile, difficulty notes, and a clear source label. A route page contains a map, downloadable route status, and text description. Keep on-trail controls large and show GPS accuracy and offline limitations. Make list/details useful without location access; provide VoiceOver descriptions and non-map access to route facts.

## Features
1. Route library: browse a small original/licensed catalog, filter by length and difficulty, favorite routes, and show route source plus update date. Never scrape commercial trail descriptions, photos, reviews, or geometry. Label sample routes as examples rather than validated advice.

2. GPX import: use the native file picker to import bounded tracks/routes, validate latitude/longitude and point counts, preview the polyline, and save it with an editable name. Reject malformed files and remove unsupported active or external content.

3. Offline pack: save route geometry, notes, and permitted images locally with progress and remove/download-again actions. If the chosen map SDK does not permit offline tiles, clearly distinguish offline route data from the unavailable basemap; never claim cached map tiles exist.

4. On-trail view: request When In Use location only on demand, show current position and accuracy on the chosen route, and calculate a nearest-polyline distance as an informational indicator. Handle denied/reduced-accuracy permission and stale location; stop updates when exiting the view.

5. Personal history: record a manual completed outing with date and notes, reopen saved routes without signal, and export an owned route as GPX. Support deletion and share-sheet cancellation, without publishing a user’s location or outing history automatically.

## Tech stack
Use Swift/SwiftUI, MapKit, CoreLocation, a bounded GPX parser, and SwiftData/Core Data. Include an Xcode project with location usage descriptions, app-managed route files, and native sharing. Do not assume MapKit supports arbitrary app-controlled offline tile downloads; choose a licensed offline-capable SDK only if that separate feature is requested and verified. Keep geometric calculations in testable Swift. No WebView substitute, AllTrails account/API, or always-on background location is required.

## Data & behavior
Route {id, name, source, license, importedAt, distanceMeters, bounds, difficultyNote}; RoutePoint {routeId, sequence, latitude, longitude, elevation}; OfflinePack {routeId, filePaths, state, bytes}; Favorite; Outing {routeId, localDate, notes}; LocationSessionState. Persist geometry and metadata together and retain altitude unknowns rather than inventing values. Put personal files in the app sandbox, support a complete delete action, and keep exact user coordinates out of analytics/log output.

Acceptance checks and scope:
Import a GPX with two track segments, save it, enable airplane mode, and verify route geometry/notes remain available with honest basemap status. Test malformed XML, large point limits, a denied/reduced-accuracy location grant, stale fixes, share cancellation, and route deletion. Build and simulate location in Xcode; verify field behavior on a device only when available. Exclude scraped trail catalogs, weather predictions, emergency guarantees, turn-by-turn routing, live sharing, background tracking, and unlicensed offline tiles.

## Originality and assets
The named product is a reference for general workflows only. Use an original product name, visual identity, wording, layout, and assets. Do not copy proprietary code, branded logos, distinctive screens, private APIs, paid templates, or protected media. Use original or appropriately licensed sample data and assets. Build from this brief rather than scraping the reference service. Do not imply affiliation with the referenced company.

## Implementation quality
- Make every visible control work, with clear loading, success, empty, validation, and failure states. Remove controls for unimplemented features.
- Support the target platform and responsive or resizable layouts where appropriate. Use platform-appropriate accessibility semantics, labels, keyboard operation, visible focus, sufficient contrast, and reduced-motion preferences. Provide alternatives for drag-only interactions.
- Validate inputs at the relevant boundary. Treat imported or user-generated content as untrusted; render it safely. Confirm destructive actions or offer undo.
- Keep state changes reliable across navigation and reloads. Never silently lose edits. Handle persistence and network errors with an actionable message.
- Keep the scope realistic. Prioritize the complete primary journey. If a custom Features section differs from the baseline, update the data model, design, and acceptance checks to match it; explicit custom requirements take precedence over baseline assumptions.
- Provide realistic original sample content and a useful empty state. Keep sample data clearly separate from user-created data.

## Delivery and verification
1. Inspect the repository and outline the implementation in a few sentences.
2. Implement the app and connect its actual data flow. Continue until the primary journey works.
3. Run appropriate checks and test the acceptance cases above on the target platform. Verify responsive layouts and keyboard navigation when browser tools are available. For native projects, build with the available SDK and test an emulator or device when possible; report any missing native verification honestly. For games, verify the rules and gameplay loop, not only the menus.
4. Fix observed failures, then provide the runnable result, setup/run instructions, a brief explanation of what is implemented, and any specific configuration or verification limits.

This is a focused MVP. Do not add billing, AI services, or unrelated features unless explicitly requested in the brief. Start building now.