ng-eventually/.project/concepts/app-contract/contract_polyfill-surface.md

---
type: contract
summary: The API @ng-eventually/polyfill exposes to an application — signatures, guaranteed behaviour, and what it does not offer
---

# contract_polyfill-surface — `@ng-eventually/polyfill`

## Scope

This package is a polyfill of NextGraph's SDK.

This package covers placement (creating and listing an application's documents by scope), reading (a document's subjects, one-shot or reactive), sharing a document with a named user, and depositing into inboxes. It does not cover user management, display names, transport, or the operation of a deployment.

### Deployment requirements

An application using this package must:

- serve a wallet file (`.ngw`) from its own bundle, and pass its URL and password to `configure` as `sharedWallet: { fileUrl, password }`;
- call `ensureIdentity()` in a browser context before rendering its interface; it mounts a barrier in the document.

## Surface

Full typed shape: the package's `types` entry, `@ng-eventually/polyfill`. A type is published only when a published signature uses it. The load-bearing signatures:

```ts
// ── bootstrap ────────────────────────────────────────────────────────────
export function configure(c: EventuallyConfig): void;
export interface EventuallyConfig {
  ng: NgLike;                                    // the `ng` object from @ng-org/web
  useShape: UseShapeLike;                        // `useShape` from @ng-org/orm
  getSession?: () => Promise<RegistrySession>;   // resolve the session (a thunk)
  normalizeId?: (id: string) => string;
  sharedWallet?: SharedWalletConfig;             // { fileUrl, password, importUrl? }
  currentUser?: PrincipalId;
  debugAccessLog?: boolean;
  init?: (...args: any[]) => any;
  initNg?: (...args: any[]) => any;
}

// ── identity — one await before the application renders ──────────────────
export async function ensureIdentity(): Promise<PrincipalId>;   // returns who you are

// ── addressing ───────────────────────────────────────────────────────────
export type Nuri     = `did:ng:${string}`;
export type NuriLike = Nuri | string;
export type Scope    = "public" | "protected" | "private";

// ── placement: where an application's documents live ─────────────────────
export const storeRegistry: {          // no identity parameter — a session is one user's
  createEntityDoc(scope: Scope): Promise<Nuri>;
  listMyEntityDocs(scope: Scope): Promise<Nuri[]>;
  resolveScopeGraph(scope: Scope): Promise<Nuri>;
  resolveWriteGraph(scope: Scope): Promise<Nuri>;
  openDocumentInbox(doc: NuriLike): Promise<Nuri>;
};

// ── reading ──────────────────────────────────────────────────────────────
export async function readUnion(docs: NuriLike[]): Promise<UnionSubject[]>;
export interface UnionSubject { subject: string; graph: Nuri; props: Record<string, string[]> }
export function useShape(shapeType: unknown, scope: unknown): unknown;   // read-filtered view
export function watchShape(query: ShapeQuery): ShapeObservable;
export function subscribeDoc(nuri: NuriLike, onChange: (r: DocChange, t: DocChangeType) => void): Unsubscribe;
export function subscribeDocs(nuris: NuriLike[], onChange: (r: DocChange, t: DocChangeType) => void): Unsubscribe;

// ── low-level document / SPARQL primitives ───────────────────────────────
export const docs: {
  docCreate(sessionId: string, crdt?: string, cls?: string, dest?: string, store?: unknown): Promise<Nuri>;
  sparqlQuery(sessionId: string, query: string, base?: string, anchor?: NuriLike, label?: string): Promise<unknown>;
  sparqlUpdate(sessionId: string, query: string, anchor?: NuriLike, label?: string): Promise<void>;
};

// ── inbox: giving to read, and depositing ────────────────────────────────
export const inbox: {
  share(doc: NuriLike, toUser: string): Promise<void>;      // give a reader the key
  post(targetInbox: NuriLike, opts: PostOptions): Promise<void>;
  postToDocument(doc: NuriLike, opts: PostOptions): Promise<void>;
  read(targetInbox: NuriLike): Promise<Deposit[]>;          // only your own
  readForDocument(doc: NuriLike): Promise<Deposit[]>;
  readSynced(targetInbox: NuriLike): Promise<Deposit[]>;
  processInbox(targetInbox: NuriLike): Promise<Deposit[]>;
  watch(targetInbox: NuriLike, onDeposits: (d: Deposit[]) => void): () => void;
  materialize: typeof read;
};
export interface Deposit { from: PrincipalId | null; payload: unknown; ts: number }

// ── the wrapped SDK objects ──────────────────────────────────────────────
export const ng: Record<string, any>;   // call this instead of the `ng` passed to `configure`
export function init(...args: any[]): any;
export function initNg(...args: any[]): any;
```

## Guarantees

Every entry accepts `NuriLike` and validates at the door; what it returns is a precise `Nuri`. No type guard is published.

A returned reference carries no key — not `createEntityDoc`, not `listMyEntityDocs`, not `UnionSubject.subject` / `.graph`. A reference found inside a document yields a name, not a key.

You read a document whose key you hold: you created it, it was shared with you, or it sits in a public store, which serves its read key to whoever asks. No call answers "may I read this?".

What was shared with you becomes readable after `ensureIdentity()`.

`readUnion` returns one entry per distinct subject present in a document. `subject` is that subject's IRI exactly as written, and is a `string`, because a subject may be any IRI; `graph` is the document reference you passed in, and is the `Nuri` to hand back to this surface. Properties of different subjects are never merged, and the same subject IRI found in two documents stays two entries, told apart by `graph`. Several objects in one document are allowed. Recommended placement is one document per business entity: access is granted per document.

`urn:ng-eventually:` is reserved. Triples whose **subject** falls under that prefix are dropped on read and never returned by `readUnion`; every other IRI is returned.

Only a document's owner writes to it. Holding its read key never grants a write.

`inbox.share(doc, toUser)` names the document and the person; the recipient calls nothing. It refuses a recipient nobody has signed in as, rather than creating them.

`inbox.post` refuses a target that is not an inbox; to reach a document's owner, use `inbox.postToDocument(doc, …)`. Anyone may deposit into an inbox; only its owner reads it.

`ensureIdentity()` settles the identity, completes the connection work it starts, and returns the identity. It takes no identifier, and no other call takes one.

`createEntityDoc` throws if the document cannot be recorded in its store.

## Non-guarantees

**No display name.** `ensureIdentity()` returns an opaque identifier: do not parse it, split it, or render it as a readable name.

**No revocation.** `inbox.share` cannot be undone.

**Nothing per reader on a document in a public store.** No grant, no revocation, no audience list.

**No delegated writing.** A received key never grants a write, and no call adds a writer to a document.

**No mailbox model.** Do not build on the raw deposit list.

**No cross-broker reference.** A returned reference resolves for users of the same broker.

**No unfiltered read through `useShape`.** Members that yield items are filtered and mutations pass through; anything else throws. A document reached through that view alone, read nowhere else first, does not appear.

## Change policy

This surface changes, and shrinks. The package does not offer semantic-version stability.

Re-pull this contract at every upgrade.