# WBV2-P3-004: IO.GLB_ROUNDTRIP LOCAL_EXACT slice

- task: WBV2-P3-004
- parent: WBV2-P3-003
- status: in_progress
- gap: IO.GLB_ROUNDTRIP
- ownerFamily: IO
- targetImplementationClass: LOCAL_EXACT

## 目标

Make the same minimal fixture produce observable IO.GLB_ROUNDTRIP data in Blender desktop and WASM/Main, with save/reopen stability. Change only this gap; do not expand to other data-blocks, editors, or browsers.

## 输入与范围

- Fixture: `tests/files/web/generated/WBV2-P3-004-IO.GLB_ROUNDTRIP.blend`
- Generator: `tools/web/generated/WBV2-P3-004.py`
- Production: `blender-5.2.0/source/blender/web_engine/web_engine_blend_reader.cpp`
- Checker: `tools/web/check-generated-gap.mjs`
- Do: field read, desktop/WASM comparison, save/reopen, structured report.
- Do not: other gaps, Firefox/WebKit, or full editor behavior.

## 验收

build_blender_5.2.0/bin/blender -b --factory-startup --python tools/web/generated/WBV2-P3-004.py -- tests/files/web/generated/WBV2-P3-004-IO.GLB_ROUNDTRIP.blend
npm --prefix web run test:generated-gap -- --task WBV2-P3-004
node tools/web/check-generated-gap.mjs --task WBV2-P3-004

Malformed/unsupported, cancellation, duplicate, over-budget, or hash-drift cases must keep in_progress; they must not change Main revision or advance nextTask.

## 交付与回滚

- Reports: `tests/golden/WBV2-P3-004/`
- Status: `docs/status/WBV2-P3-004.md`
- Manifest: `tests/golden/WBV2-P3-004/manifest.json`
- Handoff: `node tools/web/check-task-context.mjs --task WBV2-P3-004 --write`
- Rollback: remove this task production entry, fixture, tests, reports, manifest, status, and context; restore the parent as queue tail without rewriting parent evidence.