OpenBuild Gallery

A hiring sandbox: a small, deployed, open-source gallery of tiny working app-clones. Candidates pick a feature from the wishlist, open a PR, get a live preview + an automated review, and the strongest implementations get merged to production and credited. PR quality is the interview signal.

This repo is the v0 seed: one clone (a Poll) built to the bar we grade against — correct under concurrent load, tested from a clean checkout, migrated, observable.

Why the Poll clone looks the way it does

The one endpoint that matters is POST /polls/:id/votes. Its job is to stay correct when many requests race:

• Votes are append-only; the tally is a COUNT. There is no mutable counter to race on, so lost updates are impossible by construction.
• Two unique constraints enforce the invariants: one vote per (poll, voter), and one effect per idempotencyKey.
• Collisions become clean responses, never 5xx. A concurrent writer that loses a unique index gets a 409 (already voted / key conflict) or a 200 idempotent replay — the API translates the DB's P2002, it never leaks a 500.

The live probe (probes/concurrency.mjs) fires 50 concurrent votes and asserts the invariant holds with zero 5xx. That same probe is the PR gate and what the reviewer bot runs against each preview.

Layout

apps/api        Fastify + Prisma + Postgres. The Poll clone + the vote gate.
probes          concurrency.mjs (the live gate) + wait-ready.sh
.github         pr-checks.yml — green-from-clean-checkout + the live probe

Run it locally

Requires Node 20+ and a reachable Postgres. With pnpm (corepack enable):

pnpm install
cp .env.example .env                       # point DATABASE_URL at your Postgres
pnpm --filter api exec prisma migrate deploy
pnpm --filter api exec prisma db seed
pnpm -w run test                           # the invariant suite
pnpm --filter api start                    # then, in another shell:
node probes/concurrency.mjs http://localhost:3000

The loop (what candidates experience)

1. Pick a bounty (a labeled Issue) → open a PR.
2. CI runs the gate; the PR gets a preview URL; the reviewer bot posts a structured review.
3. If it clears the bar and wins the bounty, it's merged to production and credited.

See ../CONTRIBUTING.md, ../BOUNTIES.md, and ../REVIEWER-BOT.md for the process, backlog, and grading.

Non-commercial hiring sandbox. Contributions are an optional evaluation, credited under MIT, AI-use disclosed. See ../CONTRIBUTOR-TERMS-and-INVITE.md.