trimesh's 3MF loader re-reads a whole production-extension part file for
every component that points into it. A Bambu Studio project with 884
components across four ~50 MB part files grew past 3 GB within seconds
and failed both the preview conversion and the geometry fingerprint.
- Add tools/threemf_stream.py: parses each part once with lxml iterparse,
resolves each component to the single object it names, and returns each
mesh once plus its placements. The same project now converts in ~8 s at
~380 MB peak (fingerprinting ~190 MB).
- convert_3mf.py and fingerprint.py use it; the GLB stores each object once
and instances repeats. Stats are computed per placement (mirrored
placements keep a positive volume), without concatenating meshes.
- Run sidecar scripts through one queue (lib/python.js) so a preview and
background fingerprinting never load big meshes at the same time;
previews go first, and 3MFs are fingerprinted one per run.
- Surface the converter's JSON error / timeout instead of "Command failed".
- Tests with a Bambu-style component fixture (shared part, mirrored
placement, decoy object) and STL/3MF fingerprint parity.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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