Build your own Dropbox.

# Build an original app inspired by Dropbox

You are an experienced product designer and full-stack 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: Web. Explicit customized Product & audience and Tech stack requirements take precedence over this starting target.

## Product & audience
Build an original file management app called Keepbox, inspired by Dropbox. It is for individuals storing and organizing files through a browser. The core flow is uploading a file, organizing it into folders, previewing it, and sharing it through an explicit access policy when a backend is available.

## Design
Use a clean file browser with a sidebar, breadcrumb navigation, list/grid toggle, readable file-type icons, and a clear upload button. Use a restrained blue accent, familiar selection behavior, and an accessible preview dialog.

## Features
1. File operations: upload with progress, download, rename, move, and delete files. Validate size and type; handle duplicate names with an explicit rename or replacement choice.

2. Folders: create, rename, nest, and move folders; show breadcrumbs; prevent cycles and preserve stable IDs when moving contents.

3. Browse: switch list/grid views; sort by name, size, and modified date; search files and folders; mark favorites.

4. Preview and trash: safely preview images, plain text, and supported PDFs; download unsupported formats. Move deleted items to trash and restore them before permanent deletion.

5. Sharing: with backend storage, create unguessable read-only share links, optionally expiring, and allow revocation. Display exactly what is shared. In local mode, provide downloads instead of nonfunctional public links.

## Tech stack
Use the existing repository and conventions if there is one. If starting from scratch, use React with TypeScript and a practical, lightweight styling approach. Pick well-maintained libraries only when they materially help. Keep components, domain logic, and data access separate. Explain your chosen stack briefly, then begin implementation.

Follow the persistence requirements in Data & behavior. Personal tools may use IndexedDB. Products with public submission, bookings, permissions, or shared messaging require an authenticated backend with server-side authorization and durable storage. Use infrastructure already available in the environment. Do not put secrets in frontend code. If external infrastructure is unavailable, build a clearly labeled local demo, provide the schema and setup instructions, and state which shared features need configuration. Do not present simulated sharing or authentication as production functionality.

## Data & behavior
Entry {id, ownerId, parentId, type, name, mimeType, size, objectKey, createdAt, updatedAt, deletedAt}; Favorite {userId, entryId}; Share {id, entryId, tokenHash, expiresAt, revokedAt}. Use object storage for online files and a scoped authenticated metadata API. A labeled personal local MVP may store blobs in IndexedDB. Sanitize filenames and never trust extensions alone.

Acceptance checks and scope:
Test uploads and failure recovery, a folder move containing nested files, duplicate names, delete/restore, quota limits, and direct unauthorized download requests. Do not execute uploaded HTML or SVG in the app origin. Exclude desktop sync, document editing, large-file chunking, and third-party integrations.

## 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.