Build your own eBay.

# Build an original app inspired by eBay

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 auction marketplace called Bidharbor, inspired by eBay. Approved sellers list original items, buyers watch and bid on timed auctions, and the server closes each auction with one recorded outcome. Start with a single currency and a no-payment pilot with explicit bid rules.

## Design
Create an original item catalog, readable auction detail, bid confirmation, watchlist, and seller dashboard. Show the server-derived deadline, current bid, minimum next bid, and leading/won/lost states. A countdown must not be the authority that decides whether a bid is accepted.

## Features
1. Listings: create seller-owned drafts with images, description, start/end, starting amount, increment, and optional reserve. Freeze bid-affecting fields once bidding starts and moderate listing publication.

2. Discovery: search and filter active auctions, sort by ending time or price, and keep a private watchlist. Clearly label ended, cancelled, and reserve-not-met items.

3. Bidding: validate eligibility, prevent seller self-bidding, enforce server time and minimum increments, and accept bids in a transaction with concurrency protection. Use explicit bids rather than hidden proxy-bidding behavior.

4. Closing: run an idempotent worker to close overdue auctions, select the valid winner if the reserve is met, and create a durable order snapshot. Repeated worker runs cannot create duplicate wins.

5. Seller and buyer records: show bid history with privacy-aware bidder identifiers, won/sold items, no-payment fulfillment statuses, and administrator cancellation with an audit record.

## Tech stack
Use a Go API, PostgreSQL with row locking for bids, a TypeScript client, private object storage, and a scheduled closing worker. Persist UTC deadlines and expose server time. Use integer money amounts and database uniqueness constraints for auction outcomes.

## Data & behavior
Seller; Listing {state, startsAt, endsAt, startMinor, incrementMinor, reserveMinor}; Bid {listingId, bidderId, amountMinor, acceptedAt, clientId}; Watch; AuctionOutcome {winnerBidId, closedAt}; OrderSnapshot; FulfillmentEvent; ModerationAction. Keep accepted bid history immutable.

Acceptance checks and scope:
Test simultaneous equal bids, a bid at the closing boundary, stale displayed prices, repeated close jobs, reserve-not-met, seller self-bids, cancellation, and seller authorization. Exclude real payments, shipping labels, imported eBay listings, automatic proxy bidding, and second-price behavior unless explicitly added and tested.

## 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.