Tracks Bun corpus position 4229 (js/web/workers/structured-clone.test.ts).
Completed in 822e2e7:
- Preserve BunFile bytes, MIME type, name, lastModified, and lineage across structuredClone, bun:jsc serialization, and repeated cross-process serialization.
- Validate detached, duplicate, and non-transferable transfer-list entries with DataCloneError plus operation/phase/type/cause/source-stack context.
- Add an explicit 2 GiB serialization-capacity guard and bounded active subprocess probes for both over-capacity rejection and under-capacity nested round trips.
- Add permanent regression coverage for BunFile multi-hop fidelity and structured diagnostic contracts.
Verification:
- Position 4229: 128 passed, 0 failed, 0 todo, 0 unsupported.
- Positions 4227-4229: 139 passed, 3 intended debug/ASAN todo, 0 failed, 0 unsupported.