tera/CONTRACT.md

# The contract

Five designs were produced in parallel and three critics tore into them. They
collided on fifteen blocking points — four files were specified twice with
incompatible contents, three separate backends were designed for one box, and
one type name was exported twice meaning different things.

This file is the resolution. **It wins over any individual design.** Anything
implemented here must match this document; where a design said otherwise, this
document is why it changed.

---

## 0. Scope

We are building **Lumbridge's own** Tera and office, plus a **dev kit** so
anyone can run their own on their own hardware.

Not in scope, deliberately: renting or purchasing parcels, billing, per-tenant
provisioning, cluster placement, a membership/tenancy system. Federation — a
self-hosted office announcing itself to a shared Tera — is a maybe-later that
the adapter boundary leaves room for and nothing designs toward now.

**The acceptance test for every decision below**, and the one that failed
end-to-end in the design round:

> A stranger clones the repo, runs one command, gets a city, copies the
> reference office pack, and has their own office — with no Lumbridge account,
> no Supabase project, and no keys.

Two CI jobs make that testable rather than aspirational, and they gate the repo:
`git clone && npm ci && npm run build`, and `docker compose up` under `env -i`
asserting `GET /api/v1/health` → 200.

---

## 1. Stage and scene lifecycle

Two designs both created `src/engine/stage.ts` with opposite lifecycles. The
retention argument wins on measured cost: the Bay Area's heightfield is 0.53M
lattice points and about 2.3 s to build — it was 336,864 and ~1.0 s when the
pack was San Francisco alone, and it grew, which is the point. Disposing the city
every time someone steps into an office and paying a second of rebuild on the
way out is not acceptable.

- **`Stage`** (`src/engine/stage.ts`) owns *only* the renderer, the RAF loop,
  resize, and a swappable current scene. Nothing else.
- **`StageScene`** carries its own `THREE.Scene`, `PerspectiveCamera` and
  `OrbitControls`. `stage.setScene(s)` swaps; the outgoing scene is **retained
  and paused, never disposed**.
- Camera, controls, lights and picking live in a per-scene **`SceneKit`**
  helper that both `createScene` (city) and `createOfficeScene` construct.
  They do *not* live on Stage.

Rationale for the split: the city and an office cannot share a `THREE.Scene` at
all. SF's `latScale` puts one scene unit at ~94 m with 3.6× vertical
exaggeration; an office renders at 1 unit = 1 m. Two scenes, one renderer.

```ts
export interface StageScene {
  scene: THREE.Scene
  camera: THREE.PerspectiveCamera
  controls: OrbitControls
  onEnter?(): void
  onExit?(): void
  tick(dt: number, elapsed: number): void
  dispose(): void
}
export interface Stage {
  renderer: THREE.WebGLRenderer
  setScene(s: StageScene): void
  current(): StageScene | null
  dispose(): void
}
```

## 2. The office data contract — one file, one type

`src/interiors/plan.ts` was specified twice with incompatible contents, and a
fourth design imported an `OfficeDoc` no design produced.

- **`src/interiors/types.ts` is the single authored contract.** It exports
  `Office`, and must stay JSON-serialisable — no functions, no classes, no
  THREE types — because a hand-written pack and one arriving over HTTP have to
  be the same thing.
- Walls are an **explicit segment list with 1-D `openings`**. Room polygons
  imply no walls; they are floor slabs. This wins because the opening-splitting
  pass produces the walk-mode collision segments for free, and because
  auto-generating walls from shared room edges needs float-equality dedup.
- **Doors and windows are `Opening` records punched out of a wall**, not
  placeable assets. `shell.wall.ts`, `shell.door.ts` and `shell.window.ts` are
  deleted from the asset library; `shell.ts` calls a parameterised `wallRun`
  part per solid run. Shipping both would put every opening in the scene twice,
  or leave the collider with no gaps.
- **`src/interiors/plan.ts` is the `Plan` class** — the `World` analogue.
  Resolves an `Office` once into wall runs, seats, props, collision segments and
  bounds. The other design's `Placement[]` is **`Plan`'s output**, an internal
  build input, not a second authored format.
- `OfficeDoc = { id, name, floor: Office, … }` lives in `src/server/wire.ts`,
  not in interiors.

## 3. Assets

- **Procedural TypeScript only.** Every mesh is a function composing cached unit
  primitives; every texture is drawn on a 2D canvas from seeded noise. No binary
  art is ever committed. This is the same property that gives the city zero
  asset-licensing exposure, and it is worth more than the quality ceiling it
  costs.
- The **assets registry wins** over the interiors one — it is strictly richer
  (roles, quality, overrides, footprint-without-build). `src/assets/kit.ts`
  defines `AssetDef` and `AssetId`; `src/assets/materials.ts` defines
  `MaterialRegistry` keyed on a closed `SurfaceRole` union.
- **`Prop.kind` is an `AssetId`.** The prop registry and the asset registry are
  the same registry.
- Namespace is **`tera:`** (`tera:desk.workstation`), not `lse:`. A self-hoster
  registers `acme:desk.standing` with `overrides: "tera:desk.workstation"` and
  reskins without forking.
- Assets are authored in metres, 1 unit = 1 m.
- `ghostOf()` moves onto the assets `MaterialRegistry` for the wall-occlusion
  fade.

### 3.1 The art licence lands with the first asset file

Apache 2.0 covers the code. The **artistic output is additionally dedicated
under CC0-1.0**, so a mesh can leave this repo without dragging a NOTICE
obligation into someone else's project.

This is decided now, not later, and `src/assets/LICENSE-ART` plus the
`CONTRIBUTING.md` inbound terms land **in the same commit as the first file
under `src/assets/`**. Deferring it is the expensive mistake: eighteen asset
builders and a ~180-prop reference office is a lot of authored work to
accumulate before anyone states the terms, and relicensing art once
contributors exist is close to impossible.

The inbound grant must be **standing, not per-PR**. Apache 2.0 §5 supplies a
default inbound=outbound grant for Apache-2.0 only; there is no default inbound
CC0, so a single merged PR whose author never said the words leaves that
contribution Apache-only and makes a directory-wide claim false. `CONTRIBUTING.md`
therefore carries a DCO-style sentence — *by submitting a change under
`src/assets/`, you license it under Apache-2.0 and dedicate the artistic output
under CC0-1.0* — so submission itself is the grant. `LICENSE-ART` is worded as a
dedication made by the copyright holders of the material, not as a property of
the directory. NOTICE gains the carve-out, because NOTICE is what a downstream
consumer actually reads to learn the repo is not uniformly Apache-2.0.

## 4. Lighting and environment — one owner, one direction

`Environment` was exported twice meaning different things, and two modules both
constructed and mutated the same three lights.

- **`Environment` is an observation**: `{ time, sun: SolarPosition, weather }`.
- The lighting *state* is renamed **`LightingState`**.
- **`Atmosphere` is the sole light owner.** `atmosphere.apply(env) →
  LightingState`, which the scene applies. One direction, no write-backs.
- Solar position is computed locally with **no network** — a NOAA/Meeus
  implementation in `src/engine/solar.ts`, dependency-free.
- An **office with no `site` gets no Atmosphere**: `fog: null`, no
  `scene.background` drive, interior lighting is its own fixed rig. This is
  still the default and still the promise — a pack can be authored, rendered and
  shared without owning a coordinate, an account or a network.
- **An office that declares a `site` gets the same sun the city does.** This is
  the "later refinement" this clause reserved, taken up rather than a reversal of
  it: `Atmosphere` is still the sole light owner and there is still one direction
  of flow. `interiors/daylight.ts` adapts what `apply()` returned; it computes no
  light of its own.

  Two things are true only indoors, and they are the whole of the adapter:

  - **The building is rotated.** `Atmosphere` works in the city's frame, where
    −Z is north because a city pack is a map. `OfficeSite.heading` is the bearing
    the pack's −Z actually points along, and the sun is turned by it — otherwise
    "the daylight side" in a pack's comments is a label rather than a fact.
  - **The fog starts outside.** A city fog beginning 1,150 units away is fine at
    94 m per unit and is *inside the room* at 1 m per unit. The colour is kept
    and the distances are replaced.

  A sited office also gets a `sky` and a ground plane at `-site.elevation`, which
  is what makes 188 m up a tower feel different from 4 m above an airfield.

## 5. One server

Three backends were designed for one box — three ports, three frameworks, three
`deploy/Caddyfile.snippet` files that would overwrite each other.

- **One Fastify workspace**, `server/`, listening on `127.0.0.1:8431`, serving
  `/api/v1/*`. One systemd unit, one Caddy snippet.
- Weather and office routes fold in as route modules, not services.
- Env prefix is **`TERA_*`** throughout.
- The Workie sync oneshot stays the **only** second process — it is the sole
  holder of a Workie credential, and that isolation earns itself.
- Private per-user markers are **never proxied**. The authenticated browser
  calls Workie directly with its own token, so private rows never transit the
  public box.
- `Cache-Control` is fail-closed: a global hook stamps `private, no-store`, and
  a route opts in to public caching explicitly.
- Authenticated realtime is a route module in this same process, not another
  daemon. Its state is bounded and memory-only. Event credentials travel in a
  POST body, never a URL; the server owns interest filtering, motion validation,
  token rotation and revocation. The auth subject is not a peer-visible entity
  id, and no media is carried on the game-state stream.

### 5.1 Zero-config boot must actually boot

Both server designs made the same independent mistake: a weather source
defaulting to a provider that requires a contact string, with a hard failure
when it is absent — which fails the very acceptance test they named.

- `TERA_WEATHER_SOURCE` defaults to **`none`**.
- A source set without a contact is a **demotion, not a fatality**: log one loud
  line and serve the `synthetic: true` clear-day body.
- The `env -i` CI job is what keeps this honest.

### 5.2 Weather sources

`api.weather.gov` (NWS) is US-government public domain, keyless, and the default
*once a contact is configured*. `met.no` is the global fallback. Open-Meteo is
opt-in and off by default: its data is CC-BY 4.0 but its free tier is
non-commercial, which is the wrong default for a product page.

## 6. Auth

Scope-corrected: no membership tables, no tenancy.

- **`TERA_AUTH_MODE` defaults to `none`.** A self-hoster gets an open office and
  never creates an account anywhere.
- Lumbridge's own office uses `sso` mode, reusing the pattern already running on
  the fleet: the world holds **no credentials**, is handed an entry URL and a
  **server-side revalidate URL**, and enforcement happens on the server. Both
  are env vars, which is exactly what a dev kit needs.
- Where a JWT is verified directly, **HS256 against a shared secret is primary**;
  JWKS sits behind an env switch. This is a correction from verified fact — the
  fleet's Supabase issues `{"alg":"HS256"}`, so a JWKS-only implementation would
  reject every real token.
- A private office returns **404, not 403**, so the endpoint cannot be used to
  enumerate what exists.
- `@supabase/supabase-js` is a **real dependency**, and the "no surprise
  dependencies" CI check becomes an **allowlist naming why each is permitted**,
  not a count. A dynamic import of an uninstalled package fails the Vite build,
  which would have made the `auth: none` default — the committed default —
  unbuildable.

## 7. The binary gate must not fire on the self-hoster

The no-binary-art check is a promise about **this repo's committed art**, but as
designed it walked the working tree and would fail a self-hoster's build on
their own legally-clean `.glb` — while two other designs told them to put files
exactly there.

- Enumerate via **`git ls-files`**, never a filesystem walk, so untracked local
  assets are invisible to it.
- Strict over **`src/**`** — that is where the licensing argument lives.
- Hard-exempt `public/props/`, `public/kits/`, `public/offices/`, `docs/`, and
  add them to `.gitignore` marked as self-hoster space.

## 8. Geocoding — the correction that matters most

`ARCHITECTURE.md` §3.2 argued that keeping geocoded company coordinates out of
the repo solved the ODbL problem. **That reasoning is wrong**, and this is the
sharpest thing the critics found.

Containment solves licence *mixing inside the repo*. It does not touch ODbL's
actual trigger. Serving a snapshot of OSM-derived coordinates at a public
endpoint is **Publicly Using a Derivative Database**, which brings ODbL §4.3
attribution and §4.4 share-alike onto the served data regardless of where the
rows are stored. Storing them off-repo hides the obligation; it does not
discharge it.

Nothing is committed to yet — Workie has no geocoding code today — so:

- The geocoder is the **US Census Geocoder** (`geocoding.geo.census.gov`): a US
  Government work in the public domain, keyless, and covering SF, LA and NYC,
  which is every city planned.
- **Google, Mapbox and HERE do not solve this either** — their terms restrict
  storing and redistributing returned coordinates, which is precisely what a
  public snapshot does.
- The sync script records a **per-row provenance field**, and the public-shape
  assertion **rejects any row whose provenance is not on a non-ODbL allowlist**.
  The gate that already checks field names now also checks where a coordinate
  came from.
- `NOTICE`'s GEOGRAPHIC DATA block gains this next to the existing USGS/SRTM
  sentence, and `ARCHITECTURE.md` §3.2's reasoning is corrected rather than
  quietly left standing.