Build your own Lovable.

# Build an original app inspired by Lovable

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 AI app-builder workspace called Briefcraft, inspired by Lovable. It is for generating a small frontend project from a user brief, inspecting proposed file changes, previewing the result in isolation, and exporting the source. Start with one supported template and bounded file operations, not autonomous deployment or arbitrary full-stack execution.

## Design
Use an original split workspace with a build conversation, file tree/editor, and preview pane. Show proposed, accepted, building, failed, and ready states distinctly. Expose real build logs, the current source revision, and a prominent source export. Keep execution details out of user-facing claims of success.

## Features
1. Projects and briefs: create a project from one maintained frontend template, store the original brief, rename it, and manage a private project history. Each generated revision has a traceable parent.

2. Bounded generation: call a configured LLM server-side for structured file changes, validate paths/types/sizes, and show a diff before applying a new revision. Reject path traversal, secrets, binary payloads, and unsupported project configuration changes.

3. Source review: browse editable files, inspect before/after diffs, accept a generated revision, undo to a prior snapshot, and apply manual edits with revision conflict checks. The model cannot overwrite changes silently.

4. Isolated preview: build/run the permitted template in a configured disposable sandbox with resource/time/network limits, display its actual logs, and embed a separate-origin preview with an explicit restrictive policy. Never evaluate generated code in the builder’s own page or privileged server.

5. Export and recovery: download a complete source archive with setup instructions, retry a failed generation/build, stop active jobs, and retain the last usable revision. If execution infrastructure is unavailable, provide source export and a clear preview setup requirement.

## Tech stack
Use a TypeScript app/API with PostgreSQL project metadata and versioned object storage. Use the chosen provider’s official SDK for structured generation. Isolate all builds in an available sandbox service or constrained disposable container on a separate origin; use server-owned allowed templates and a verified dependency allowlist. No arbitrary shell commands on the main app host.

## Data & behavior
User; Project {ownerId, templateId, currentRevisionId}; BriefMessage; Revision {parentId, sourceManifestHash}; FileSnapshot {path, contentHash, bytes}; Proposal; BuildJob {revisionId, state, sandboxId, expiresAt, logs}; Export. Validate every generated path and enforce project ownership before fetching source or logs.

Acceptance checks and scope:
Test brief/generate/review/build/export, invalid structured output, traversal paths, missing provider credentials, malicious preview code, a build timeout, cancellation, and concurrent manual edits. Verify the exported archive runs with its documented setup. Exclude automatic publication, secrets management, arbitrary backends, and unrestricted package installation.

## 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.