# Experiment GLB compression

## Goal

Create and validate a repeatable GLB compression experiment for
`nantaizi-lake-innovation-valley`, focused on reducing file size without making
the current uncompressed GLB output the wrong baseline.

Current measurement:

- `nantaizi-lake-innovation-valley.glb`: `20.50 MB`
- embedded images: `17.72 MB`
- non-image binary buffer: `2.45 MB`
- conclusion: texture compression / resize should be tested before geometry
  compression.

## Requirements

1. Add a standalone compression tool or script that consumes an existing GLB and
   writes a separate compressed GLB output.
2. Do not replace the default `<area>.glb` in this first experiment.
3. Prefer texture-first compression; geometry compression may be evaluated but
   should not be treated as the primary win.
4. Keep the experiment repeatable from the command line.
5. Validate only `nantaizi-lake-innovation-valley`.
6. After visual review accepts the WebP result, integrate it as an explicit
   optional `compress` stage that does not run in `all` and does not replace the
   default GLB.
7. Report:
   - source GLB size
   - compressed GLB size
   - image vs non-image size before compression
   - GLB extensions introduced
   - Cesium preview compatibility status or blocker

## Acceptance Criteria

- [x] Compression command/script runs from this repo.
- [x] It produces a separate compressed GLB for nantaizi.
- [x] Source GLB is left intact.
- [x] `scripts/glb-digest.js` can inspect the compressed GLB or the blocker is
      documented if the digest needs extension support.
- [x] Visual/Cesium compatibility next step is clear.
- [x] Optional `compress` stage can generate compressed nantaizi artifacts from
      the existing Cesium outputs.
- [x] `compress` is not included in `all` and cannot be enabled from area
      `stages`.
- [x] No `outputs/` files are committed.

## Out Of Scope

- Making compressed GLB replace the default pipeline artifact.
- hanyang validation.
- CDN/server gzip/brotli configuration.
- Large frontend UI changes.