Durable plan for the next step: drive the engine against the mock platform
(spec/harness.sx :fetch + web/harness-web.sx simulate-click/DOM asserts), so
fetch->swap->DOM behavior is tested without a browser — the same engine could
drive a non-browser target. Phases: PoC (relate-delete), port the rest, trim
Playwright to WASM-boot + content-addressed-load, stretch = non-browser renderer.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>