Negotiate and decode snapshot-bound canonical model streams

src/lib/canvas-runtime/contracts.ts

@@ -1,6 +1,6 @@
 import type {OrphanFile} from './orphan-files.ts';
 import type { ImportJob } from './imports.ts';
-import type { Document, Id, Json, OperationIntent, Snapshot } from '../canvas-core/types.ts';
+import type { CanvasRecord, ElementRecord, Document, Id, Json, OperationIntent, Snapshot } from '../canvas-core/types.ts';
 import type { LedgerSnapshot, FrozenRequest } from './ledger.ts';
 import type { CompiledRequest, OperationStatus } from './scheduler.ts';
 import type { RunRecord } from './runs.ts';
@@ -22,6 +22,8 @@ export type RuntimeState = {
 };
 export type EngineSnapshot = Snapshot<RuntimeState>;
 export type CanonicalProposal = { readonly document: Document; readonly versions: ReadonlyMap<Id, number> };
+/** Receiving records are read deltas, not a validated Document or an ACK base. */
+export type CanonicalReadUpdate = CanonicalReadResult | { readonly status:'receiving'; readonly projectId:Id; readonly canvases:readonly CanvasRecord[]; readonly elements:readonly ElementRecord[]; readonly tombstones:ReadonlyMap<Id,number>; readonly versions:ReadonlyMap<Id,number>; readonly receivedElements:number; readonly totalElements:number };
 export type CanonicalReadResult = ({ readonly status: 'ready' } & CanonicalProposal) | { readonly status: 'migration-required'; readonly rootId: Id; readonly sourceVersions: ReadonlyMap<Id, number> };
 /** A validated historical execution receipt; its old model is never published over a fresh read. */
 export type AppliedModelProof = { readonly versions:ReadonlyMap<Id,number>; assertCanonical(proposal:CanonicalProposal):void };