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ADR-0003: License — Apache 2.0

  • Status: accepted
  • Date: 2026-05-03

Context

The source repository (joernmht/raiLPminerExperimentation) is MIT-licensed. The new repo can choose any license at least as permissive that satisfies our goals.

Decision

Apache 2.0. Source repository attribution is preserved in docs/extraction-report.md and in per-file headers where code is extracted or refactored.

Rationale

  • Apache 2.0 has an explicit patent grant. MIT does not. For a library used in research and industry alike, the patent grant matters.
  • Apache 2.0 is OSI-approved, FSF-approved, and broadly compatible with downstream consumers.
  • Compatible with the source repo's MIT (we may incorporate MIT code with attribution into an Apache-licensed work).

Consequences

  • Every file extracted or refactored from the source repo carries a header crediting the origin and noting the original MIT license.
  • LICENSE is the Apache 2.0 text; an appendix notes the partial MIT derivation.
  • Contributors agree to license their contributions under Apache 2.0 (the standard implicit DCO is sufficient; we do not require a CLA at v0.1).

Alternatives considered

  • MIT (matching the source): no patent grant.
  • BSD-3-Clause: similar to MIT, no patent grant.
  • LGPL: incompatible with our use cases (proprietary downstream embedding).
  • MPL-2.0: file-level copyleft is unusual for a Python library; would surprise contributors.