Prior-Art Record — Event-Sourced Geometry as a Fold over a Signed Operation Log¶

Defensive publication / authorship record. First published 2026-06-18 by the BIM OOTB project (red1oon). This page is a dated, public, enabling disclosure of the architecture described below so that it stands as prior art. It is the geometry-side companion to the Feature Comparison (BIM viewer) and Migrate & Compare (ERP) (the WASM event-sourced browser ERP).

What is disclosed¶

A single cryptographically hash-chained operation log (an append-only, tamper-evident event log — "git for data") serving as the sole source of truth for both (a) ERP transactional records and (b) BIM parametric geometry, executed entirely in the browser client with no server, where geometry is not stored but is a deterministic fold — a pure replay of the logged feature operations through a reused boundary-representation (B-rep) geometry kernel.

In this architecture a parametric feature (e.g. a wall as an extruded profile, an opening as a boolean cut) is recorded as one signed row in the operation log: an operation type plus its parameters. The rendered solid is obtained by replaying that row through the kernel. Undo, redo, history scrubbing, branching, design variants ("multiverse"), distributed sync, and audit are therefore not separate features of the modeller — they are intrinsic properties of the log, shared identically with the ERP records that ride the same log.

Precise scope of the claim (what is, and is NOT, claimed novel)¶

We do not claim first authorship of:

Event-sourced / replayable CAD architecture in general — this is a recognised pattern (see the event-sourced collaborative-CAD literature) and is partially embodied by commercial cloud CAD.
Cloud parametric feature history with branch & merge — shipped and patented by others (Onshape / PTC). Their implementation is server-authoritative cloud.
Browser-resident OCCT/B-rep CAD — demonstrated by Chili3D and ifc5cad (both AGPL).
Model versioning / immutable audit trails of committed states — demonstrated by Speckle.

We record as prior art, as of the date above, the specific combination none of the above embodies:

A single tamper-evident, hash-chained operation log that is the sole source of truth for both ERP records and BIM parametric geometry, run fully client-side, in which geometry is derived as a deterministic fold (replay) over the log rather than stored — demonstrated by a working reference implementation (below).

Feature comparison — where this sits among prior systems¶

Capability	BIM OOTB (this work)	Onshape	Chili3D	ifc5cad	Speckle	Bonsai / IfcOpenShell
Parametric feature history	✅	✅	✅ (in-memory undo)	✅ (in-memory undo)	—	✅ (in-memory undo)
Geometry derived as a fold (replay), not stored	✅	✅ (server)	❌	❌	❌	❌
Cryptographically signed / tamper-evident log	✅	❌	❌	❌	❌	❌
*One substrate for ERP records and* geometry**	✅	❌	❌	❌	❌	❌
Runs fully client-side (no server)	✅	❌	✅	✅	partial	desktop
Branch / variant / distributed history	✅	✅ (patented)	❌	❌	✅ (versions)	❌
Reuses an open B-rep kernel	✅ (OCCT)	❌ (proprietary)	✅ (OCCT)	✅ (OCCT)	n/a	✅ (OCCT)

The distinguishing intersection — signed log + geometry-as-fold + unified ERP+BIM substrate + fully client-side — is held by no prior system in the row above.

Reference implementation (enabling disclosure)¶

The mechanism is demonstrated, not merely asserted. The reference reuses the open-source occt-wasm kernel (OpenCASCADE compiled to WebAssembly) as a stateless pure function and our own signed operation-log engine as the feature tree.

A feature is recorded as one log row, for example an extruded-area solid (the dominant BIM geometry form):

op_type    = "GEOM_EXTRUDE"
parameters = { "profile": { "w": 4, "h": 0.2 }, "dir": [0, 0, 3] }

Replaying that row builds a rectangular profile and extrudes it; an opening is a second row whose replay cuts a boolean void from the wall. The witness (W-KERNEL-FOLD, 2026-06-18) records that replaying a serialised log row reproduces byte-identical geometry, and that boolean openings fold deterministically:

init ok                                          (kernel loads in-browser)
live    tris=12  bbox=[0,0,0,4,0.2,3]  cs=1782029157     extrude → wall
replay                                 cs=1782029157  identical=Y   ← fold is deterministic
opening tris=32                        cs=3687298821  deterministic=Y  changedVsWall=Y

cs is a checksum of the tessellated vertex positions; identical checksum across an independent replay establishes that the geometry is fully determined by the log row — i.e. geometry is a fold over the log.

Engineering facts established by the reference¶

The kernel is single-threaded (no SharedArrayBuffer), so it requires no cross-origin isolation (no COOP/COEP) and runs on ordinary static hosting.
Geometry replay is deterministic for both extrusion and boolean operations under fixed tessellation.
The reused kernel is embedded as a separately-loadable WebAssembly module, preserving the open-source kernel's licence terms while the surrounding application remains independently licensed.

Provenance¶

This disclosure is timestamped by its publication to the project's public documentation site and by the project's version-control history. It is intended to establish the date and authorship of the combination described, and to serve as prior art against later claims to that combination.

BIM OOTB — red1oon — first published 2026-06-18.