Problem

After updating to @playcanvas/splat-transform@2.7.1 and playcanvas@2.20.2 (#929), HTML and ZIP viewer export stopped working: the output file and its .crswap temp were created on disk but 0 bytes were written, with no error dialog. Plain SOG export was affected too, since all three share the same write path.

Root cause

splat-transform 2.6.0 ("Parallelize SOG writing with a cross-platform worker pool") rewired writeSog to offload runQuantize1d / runEncodeWebp onto a WorkerQueue. Our 2.5.1 → 2.7.1 bump crossed that change (writeHtml itself is unchanged between the two versions).

In the published build the pool is not inline by default (WorkerQueue.isInline is false). We never configure it for our browser bundle — main.ts only sets WebPCodec.wasmUrl — so the pool tries to spawn new URL('./worker.mjs', import.meta.url), which resolves next to our bundle and 404s (we don't ship that worker). A single failed-worker task falls back to inline correctly, but under the parallel task load that real SOG writing generates, the pool hangs instead of falling back — so writeSog never completes and nothing is written.

Fix

Force SOG writing to run inline (the pre-2.6.0 behavior), alongside the existing WebPCodec config in main.ts:

import { WebPCodec, WorkerQueue } from '@playcanvas/splat-transform';
...
WorkerQueue.maxWorkers = 0;

With the pool disabled, no worker spawn is attempted and writes run on the calling thread, exactly as in 2.5.1.

Verification

• tsc --noEmit passes.
• Reproduced the hang directly against the installed 2.7.1: 16 parallel quantize tasks with an unreachable worker hang before the change, and complete inline (16/16) with maxWorkers = 0.

Notes / follow-ups

• Trade-off: SOG writing in the editor is serial again (no worker parallelism). To restore it later, ship splat-transform's worker.mjs as a static asset and set WorkerQueue.workerUrl to it.
• Latent splat-transform bug (out of scope here): WorkerQueue hangs under parallel load when workers can't spawn, rather than degrading to inline. Forcing inline sidesteps it, but it would bite any browser consumer that enables the pool without shipping the worker.