Assembly.attach ​

Contract 2.0.0 · package sha256 a857eca95b35921109faf997094bb4192f12527d9d0fcd4be7e97f06425bad6e · generated from configurator-runtime.d.ts by services/onsite-scripter/scripts/build-contract-docs.mjs; edit the source, not this file.

Method of Assembly · stable · since 2.0.0 · called as session.assembly.attach

attach(node: string, options?: RecordedOptions<C> & AttachOptions): Promise<AttachReport>;

Attaches node by its connectors (recorded; merging; in the write queue): moves its model root and records the connection. Spec section 6.12 is the normative table. In short: placement honours the stored plane config (align, frontDir, allowRotatedSnap) exactly as 1.4 snapTo did; it refuses only a disabled connector or one occupied by another pair (re-attaching a connected pair re-places node), an accepts mismatch where accepts is declared, or planes that don't meet; it never moves another node, and it drops node's other connections that no longer meet after the move ('connection-stale'). A refused attach changes nothing. dryRun reports without changing. Through a tx: 'staged', and a dropped connection that the same transaction attaches again is not a problem. Not for: moving nodes by pose, which is never recorded as a connection. Errors: a refusal resolves (attached: false), never rejects, and so does an internal failure ('rolled-back', 'internal-error'; spec section 6.4); invalid input rejects HoloInputError. Other connections it drops are problems ('connection-stale').

Options ​

Through Session:

Through Tx:

Refused here (typed never, so passing one fails to compile): actor, checkpoint, dryRun, expectGroup, expectRevision, origin, supersede, undo.

Abort (signal) ​

This call is a write (SignalOption.signal, the kinds of call).

A write: before the commit point it rolls back and rejects AbortError; after it, no effect, except that a running camera move stops where the last frame drew it (CameraMoveOptions).

Through a tx the commit point is the transaction's: aborting a write still loading rejects AbortError and stages nothing (catch it: unobserved, it rolls the transaction back, spec section 6.1, O6); aborting one already staged unstages it, its paths keeping the latest other write to them as after a failed savepoint (O7), and its Promise stays resolved 'staged'.

Example ​

Imports: values (has, validate, the Holo*Error classes, the pure helpers) from @holostep-configurators/runtime-client, types from @holostep-configurators/runtime-client/contract, /math and /testing names from those entries; boot from the runtime module the root's loadRuntimeAtFloor resolves to. A type your page defines is your app's: declare it there, never import it from the package.

Compiled under the contract's strict settings (examples/declaration/12-Assembly.attach.ts):

import type { DeepReadonly, IModelNode, Reason, SceneModel, Session } from '@holostep-configurators/runtime-client/contract';
declare const session: Session;
declare const signal: AbortSignal;
// Add an arm and attach it, in one undo step; a refusal rolls the add back too. For an app whose
// scene model is its source of truth: a store app adds in its store and lets its one sync write
// the model (spec section 11.2), or a sync rolls this back, or its next sync drops the arm.
class AttachRefused extends Error {
  constructor(readonly reason: Reason) { super(`attach refused: ${reason}`); }
}
declare function withNode(model: DeepReadonly<SceneModel> | null, node: IModelNode): SceneModel;
export async function addArm(arm: IModelNode, seatId: string): Promise<Reason | 'superseded' | null> {
  try {
    const r = await session.transaction(async (tx) => {
      // staged and loaded, hidden
      await tx.setSceneModel(withNode(tx.getSceneModel(), arm));
      const a = await tx.assembly.attach(arm.nodeId, {
        from: 'mp-left',
        to: { node: seatId, connector: 'mp-right' },
      });
      // 'occupied' | 'rejected' | 'no-candidate' | 'not-loaded'
      if (!a.attached) throw new AttachRefused(a.reason ?? 'other');
    }, { undo: 'Add arm', origin: 'arm-ui' });
    if (r.outcome === 'superseded') return 'superseded';    // a newer write won: not a refusal
    return r.outcome === 'committed' ? null : (r.reason ?? 'other');
  } catch (error) {
    // the transaction rolled back
    if (error instanceof AttachRefused) return error.reason;
    throw error;
  }
}

Generic-API test (spec 3.1) ​