Gridfinity Builder

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ZIP and STL export verification ​

The default toolbar download is a ZIP with model.3mf, one binary STL per part, and README.txt. 3MF only preserves direct 3MF downloads. All three actions use the same packaging function: selected bin, full layout, and fit kit. Geometry generation, cached worker buffers, saved layouts, and mating profiles are unchanged.

Automated checks ​

Run npm test -- src/gridfinity/exportBundle.test.ts src/gridfinity/export3mf.test.ts. On 2026-09-12 all 12 focused tests passed; the complete suite passed 56 tests across six files. The production application and documentation builds were also checked separately.

  • Binary STL uses little-endian float32 coordinates, a triangle count, unit normals, and zero attribute bytes, following the documented binary STL structure.
  • Empty/malformed buffers, non-finite coordinates, invalid indices, and entirely degenerate meshes fail explicitly.
  • Float32 extraction can collapse an edge. Exactly zero-area STL facets are omitted; small positive-area facets are preserved without a tolerance cutoff.
  • An independent Three.js STLLoader reads the output. The three fit-kit parts are rebuilt in Manifold to check closed, connected solids, positive volume, original volume, dimensions, and placement against the nested 3MF.
  • ZIP CRC checks cover the outer archive and nested 3MF. Numbered, sanitized STL names preserve duplicate labels without paths or file overwrites.
  • Direct 3MF export remains covered; source mesh buffers are not modified.

The initial fit-kit STL test caught the zero-area facets before delivery. The final test verifies their removal does not change the printable solid.

Browser download check ​

Run a production preview and launch Chromium with an isolated profile and loopback-only CDP. Supply a fresh empty directory writable by that browser:

bash
npm run preview -- --host 127.0.0.1 --port 4174 --strictPort
# In another terminal, with Chromium/CDP already running:
node scripts/check-export-browser.mjs http://127.0.0.1:4174 /absolute/path/to/empty-download-directory

The harness uses a disposable two-bin layout and real toolbar controls. It checks that ZIP is selected by default, downloads all bins, the selected bin, and the fit kit, then selects direct 3MF and downloads again. It opens the four actual browser-downloaded files, checks ZIP CRCs, STL record lengths, 3MF units, and object counts. It does not intercept or replace the download function.

All four downloads passed locally in Chromium 152.0.7977.64 with zero browser exceptions. The harness closes its own tab, preserves downloaded evidence, and refuses a nonempty download directory to avoid accepting stale files. The same command accepts the public application URL for a post-deployment check.

Limits and rollback ​

STL has no standard unit field; its numeric coordinates are millimetres. The ZIP instructions require extraction and importing either format at 100% scale, not both. No physical printer, automated slicer import, or independent 3MF schema/OPC validator is claimed by these tests.

Rollback the packaging unit by reverting exportStl.ts, exportBundle.ts, its tests, the browser harness, and the toolbar integration together; restore the associated export/fit-test documentation. Keep the geometry generators and security policy. This restores the previous direct-only 3MF workflow without altering saved layouts or mating dimensions.