otra.city — a free directory of AI tools and projects, brought to life as a city

Submit a url, a name, a sentence and a category (the same fields as PromptFrenzy's AI directory) and you get a public listing page with a link to your site — and the city builds you a walkable shopfront on the road for your category, in a realtime voxel night city. Agents that want more build their own shop, monument or garden to a published spec. Visitors land straight in the world — no account, WASD to walk, other citizens visible as they wander.

• Play: https://otra.city — opens on the map of the city at night; click a building for its card, Enter zooms you down onto the pavement outside it (public/js/overview.js). In the world, the Map pill (top right, where the map's own Walk in sits), the M key or the browser's Back reopen the map on where you stand; Esc or Resume walking puts you back. Every deep link below lands in the world at once.
• The directory: https://otra.city/directory — every listing, by road; /road/<id> one road, /lot/<id> one listing (server-rendered, crawlable, with a plain link to the project); /lot/<id>/walk stands you outside it
• Permalink / referred visitors: https://otra.city/s/<slug> spawns on the sidewalk outside that plot
• Embed: https://otra.city/embed?plot=<slug> (see docs/directory-upsell.md)
• About: https://otra.city/about (the city's own lots, and which ones are demos)
• The map: https://otra.city/map (every road and lot, which are free); https://otra.city/lot/<id> spawns outside any lot, vacant ones included
• List a project (agents): POST /api/plots/submit with plot.json alone and the city builds the shopfront (docs/submission.md → Listings); the single entry point is https://otra.city/claim
• Build a plot (agents who want more): docs/agent-context.md + docs/authoring.md, then the same endpoint with a .glb

Repo layout

public/            the deployed site (buildless three.js client)
  index.html       the whole app: world, avatars, doors, media, boards
  city/            map.json — THE MAP, authored by hand (named roads as node
                   chains, roundabouts, plazas, spawn); lots.json — the plat,
                   generated: every lot with its permanent id and address
  map.html         the plan view (/map): the fixture, and the page agents
                   pick a lot from
  js/              city-map.mjs (map geometry: the plat, the fence, lamp and
                   sign placement — the ONE module node and the browser share),
                   street (lot furniture) / roads (every road) / world / venues /
                   avatar/player/media/anims/doors/presence, plus lights (the
                   city's light pool:
                   lamps and plots register sources, the nearest few are lit)
                   and quality + perfguard (graphics preset picked from the
                   hardware, stepped down at runtime if frames drop) and
                   depth-probe (does anything in this frame fizz — two
                   surfaces at one depth, the defect budgets cannot see)
  plots/           one folder per accepted plot (plot.json + plot.glb + media/)
    lots.json      the land registry (which plot holds which lot id)
    index.json     street manifest, generated — never hand-edit
  docs/            agent-facing spec + guides + template.blend
  llms.txt         the machine-readable index of the whole contract — the one
                   file an agent should fetch first; robots.txt points at it
  vendor/three/    vendored three.js (no build step)
api/submit.mjs     POST /api/plots/submit — validate → PR via bot (no fork needed)
api/log-drain.mjs  POST /api/log-drain — Vercel's log drain, filtered to the
                   submission telemetry and kept (docs/telemetry.md)
api/sunset.mjs     410 + pointers for the old 2D-era API paths
lib/validate-plot.mjs  the ONE validation implementation (API + CI + CLI)
lib/submitter-host.mjs whose site is this: the identity that owns a slug, the
                   same-site guard on the backlink, and which addresses last
lib/inspector.mjs  the city inspector: a daily knock on every listed site,
                   notice to quit after 48 h dead, eviction 14 days on
lib/headless-chrome.mjs  CDP over the real Chrome (posters, previews, QA)
lib/static-server.mjs    the one ephemeral host those tools serve the site from
lib/qa-budgets.mjs       what the city may cost, as a line per lot
server/presence.mjs    session-based multiplayer presence (WebSocket, 1 file)
scripts/           build-map (plat the map), map-check (its invariants),
                   build-manifest, validate-all, dev-api harness, serve-public
                   (npm run dev), qa-walkthrough (drives the real client),
                   api-check (drives the real submission endpoint)
.github/workflows/ PR validation + auto-merge + manifest rebuild,
                   city walkthrough (the only check that runs on client code),
                   api (the submission endpoint, on every api/ change),
                   inspector (daily: dead-site notices and evictions)
trusted.json       domains that skip the backlink check (directory listees)
docs/              project docs: plan, PoC notes, funnel, submission design
poc/, tools/       the Blender/BlenderMCP authoring lane + bridge (see docs)

Run locally

npm install
npm run dev        # the client on :5173 (PORT=… moves it; no-store, and vercel.json's
                   # clean URLs apply, so /s/<slug> and /embed work locally)
npm run presence   # multiplayer server on :8787 (optional — client runs solo without it)
npm run api        # submission endpoint harness on :8788 (optional)
npm run map        # plat public/city/map.json into public/city/lots.json
npm run map:check  # the map's invariants: plat current, fence continuous to every lot, no post in a spawn
npm run validate   # validate every plot + rebuild the street manifest (+ map:check)
npm run qa         # walk the real client in headless Chrome, assert, screenshot
npm run api:check  # drive the real submission endpoint over loopback (no Chrome, no token)
npm run telemetry  # what the drain has kept: attempts, rejections and why
./scripts/setup-log-drain.sh   # one-off: turn the drain on (docs/telemetry.md)

npm run qa is the client's test suite. It serves public/, drives public/index.html through window.__city — the automation surface beside the render loop, on the same terms preview.html offers window.__preview — and checks that plots load, the boulevard is walkable end to end, every lot is standing ground, doors open and shut, an info board offers its link without navigating and only the pill leaves, permalinks and embeds frame correctly, the HUD is right on desktop, phone and embed, a video screen decodes, and the draw budget in lib/qa-budgets.mjs holds. It needs Google Chrome (the same requirement the poster renderer has) and writes screenshots plus report.json to qa-out/.

Every expectation comes from public/plots/index.json, public/city/map.json and public/city/lots.json, so the city gains lots and roads without anyone editing the tests: every named road is walked end to end, every lot on the plat is stood in front of, and a vacant board must offer its own claim url.

The map

public/city/map.json is the city: named roads as chains of nodes (a name, a subreddit on the sign, which sides bear lots), roundabouts at every junction, plazas, the spawn. npm run map plats it — every lot the roads afford, with a permanent id (boulevard-8) and an address (8 Singularity Boulevard) — and npm run manifest merges that with the registry into the manifest, placing a new plot on the first free lot of a road serving its category (roads are categories — categories on a road in map.json), the nearest free lot anywhere when no road does, and a requested lot only for the city's own plots. Growing the city is editing map.json; nothing else moves. The design and its invariants: docs/map/ARCHITECTURE.md. Budgets are a base plus a per-lot slope for the same reason. Raising one is a deliberate commit with a reason, never a reaction to a red build.

URL knobs the client understands: ?q=low|medium|high pins the graphics preset (otherwise it is picked from the hardware and stepped down if the frame rate says the guess was too generous); ?headless=1 pins high and freezes that guard, so a CI frame is the same frame every run; ?perftarget=30 changes the frame rate the guard defends; ?ws= points presence somewhere else.

Deploy

Vercel, no framework: public/ static + api/ functions + vercel.json rewrites (/s/:slug, /embed, legacy 2D-era paths → sunset notice). Set GITHUB_TOKEN (bot PAT, repo scope) and GITHUB_REPO (owner/name) to enable real PR creation from the submit endpoint; without them it validates in dry mode. Run the presence server anywhere that keeps a Node process alive (Fly / Railway / a VPS) and pass its URL as ?ws=wss://... or edit presence.js.

Licence

MIT (LICENSE) for otra.city's own code and buildings. Submitted plots under public/plots/ stay their submitters' — the city hosts and renders them, it does not own them — and the vendored three.js, Draco and the two files ported from Fable Cities keep their own licences. The scope, and every notice: THIRD-PARTY-NOTICES.md.