ADR 0003 — uniTube is BSD-2-Clause; prior art is quarantined

Status: accepted (2026-08-21) · amended 2026-08-21 — see below

Context

The repository had no root LICENSE while mixing five regimes: public domain (maths.scad), BSD-3 (pipe-joints/), GPL unspecified (vector.scad), GPLv3 (path_extrude.scad, Round_Ducting), CC-BY (curvedPipe/LICENSE.txt), and one file copied from a personal blog with no licence statement at all.

The binding problem: GPL vector.scad was use <>d by every core file, and OpenSCAD’s use <> is source-level inclusion at parse time. The conservative reading is that uniTube as it stood had to be GPL — a real adoption tax for a library meant to be dropped into commercial part designs, and in direct conflict with the BSD-3 pipe-joints code already in the tree.

Decision

  • uniTube is BSD-2-Clause.
  • All third-party and historical code moves to reference/, which is a read-only quarantine. No file under src/ may import from it, enforced by just lint (rule 2 in AGENTS.md).
  • Provenance for every retained file is recorded in NOTICE.
  • vector.scad’s six consumed functions are reimplemented from their mathematical definitions in src/ut_math.scad. cross and norm are OpenSCAD builtins; the vendored versions were shadowing them.

Consequences

  • With ADR 0001 (no dependencies) there is now no upstream licence to accommodate at all.
  • The axford lineage is CC-BY, which is attribution-only and would be workable with a credit line. It is still reimplemented rather than forked, because someShapes.scad claims “Public Domain” while admitting it borrowed from GPLv3 Mendel90 — a contradiction unresolvable from the files. The affected code is ~20 lines of linear_extrude/rotate_extrude; rewriting is cheaper than adjudicating. axford is credited in README.md and NOTICE.
  • reference/jantecnl/ has no licence of any kind. Only its run coordinates are used, as a test fixture. If provenance is ever contested, deleting that directory costs nothing.
  • Lint cannot detect copy-paste. reference/gringer/path_extrude.scad is GPLv3 and is the most tempting file to crib from while writing src/ut_mesh.scad. This is called out in NOTICE and AGENTS.md.

Amendment — reference/jantecnl/ deleted

This ADR originally kept the 4-into-1 prototype on the grounds that “only its run coordinates are used, as a test fixture” and “if provenance is ever contested, deleting that directory costs nothing”.

It has been deleted. The coordinates are now first-party geometry in examples/06_manifold_4into1.scad, so the directory bought nothing but a file with no licence statement of any kind sitting in a repository whose whole licence story is otherwise clean. The historical record survives in docs/developer/history.md §4 and in the git history.

Everything else in this ADR stands.

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