NOTICE

ECHIDNA - Extensible Cognitive Hybrid Intelligence for Deductive Neural Assistance
Copyright (c) 2024-2026 Jonathan D.A. Jewell and ECHIDNA Project Contributors

LICENSING

This project is licensed under the Mozilla Public License, version 2.0
(MPL-2.0), with its documentation under Creative Commons
Attribution-ShareAlike 4.0 (CC-BY-SA-4.0).

  Full text:               LICENSE  (also in LICENSES/MPL-2.0.txt)
  SPDX-License-Identifier: MPL-2.0

Three parts of the tree, two licences:

  1. CODE AND SPECIFICATION SURFACE          MPL-2.0
     The Rust core, Julia ML layer, Zig FFI, Chapel parallel layer, SPARK/Ada
     units, proof corpora, build system and CI; and everything under
     .machine_readable/ (descriptiles, contractiles, K9 configurations,
     anchors, policies), the AI manifest, the package and container
     manifests, and the OCI image labels emitted by the stapeln / svalinn
     build tooling. MPL-2.0 is file-level copyleft: modifications to these
     files must stay open, but combining them with other code, or
     implementing against the specification surface, carries no obligation
     on the rest of a larger work.

  2. DOCUMENTATION             CC-BY-SA-4.0
     Everything under docs/, plus the top-level Markdown and AsciiDoc
     documents.

  3. echidna-playground/       MPL-2.0
     The Coq-Jr playground sub-project, which carries contributions from
     Coq-Jr Contributors rather than the ECHIDNA project. It has always been
     MPL-2.0 and is NOT relicensed.

Files that previously offered `Palimpsest-0.6` now carry MPL-2.0. The
Palimpsest Licence is MPL-2.0 with additional ethical provisions layered on
top, so MPL-2.0 is the faithful reduction when the Palimpsest layer is not
being asserted. See "THE PALIMPSEST FRAMEWORK IS NOT A LICENCE GRANT HERE"
below.

Until the remaining `.a2ml` manifests are converted to `.deed`, a handful of
them (and one training-data file) still carry an AGPL-3.0-or-later SPDX
header; LICENSES/AGPL-3.0-or-later.txt is retained for them in the interim.
Those headers are stale, not a carve-out: the owner's 2026-10-01 ruling
places the whole of the project's own code under MPL-2.0. See docs/DEBT.adoc.

THE PALIMPSEST FRAMEWORK IS NOT A LICENCE GRANT HERE

ECHIDNA references the Palimpsest License as an ethical / philosophical
framework - a discipline about how contributions are received, attributed and
forwarded. That reference stands, and is orthogonal to the SPDX identifiers
above.

It is not a legal grant in this repository. The Palimpsest licence proper is
the legal licence only on `palimpsest-license`, `palimpsest-plasma` and
(prospectively) `consent-aware-http`. Some files here previously carried
`... OR Palimpsest-0.6` or `... AND Palimpsest-0.6` SPDX identifiers; those
were drift rather than a deliberate grant, referenced a version superseded by
the `palimpsest-license` repository, and had no licence text distributed with
this repository. They were removed in 2026-08.

LICENCE HISTORY

  dual MIT / Palimpsest-0.6  ->  MPL-2.0  ->  AGPL-3.0-or-later for
  application code, MPL-2.0 for the specification surface (2026-08)
  ->  MPL-2.0 throughout, CC-BY-SA-4.0 for documentation (2026-10-01)

The owner re-ruled ECHIDNA onto the estate default on 2026-10-01 (ruling
D262), superseding the 2026-08 AGPL decision. Copies obtained between those
dates under AGPL-3.0-or-later remain available to their recipients under
that licence; everything from 2026-10-01 is MPL-2.0. Documents predating the
re-ruling may describe application code as AGPL; LICENSE and this file are
authoritative.

================================================================================

THIRD-PARTY SOFTWARE

This project includes or depends on third-party software components with their
own licences. See the respective component directories and files for details.

Rust dependencies:    Cargo.toml + `cargo license`
Julia packages:       Project.toml + Manifest.toml
Bun scripts:          scripts/*.js (bun built-ins only, no third-party packages)

Theorem provers (integrated, not redistributed):
  Agda            BSD-3-Clause
  Coq / Rocq      LGPL-2.1
  Lean 4          Apache-2.0
  Isabelle/HOL    BSD-3-Clause
  Z3              MIT
  CVC5            BSD-3-Clause
  Metamath        Public Domain
  HOL Light       BSD-2-Clause
  Mizar           GPL-3.0
  PVS             GPL-2.0
  ACL2            BSD-3-Clause
  HOL4            BSD-3-Clause
  (...and the remaining backends; see docs/SUPPORTED_PROVERS.adoc)

Provers are invoked as external binaries, not linked or redistributed, so
their licences do not propagate to this work.

================================================================================

REUSE COMPLIANCE

This project follows the REUSE Software Licensing specification.

  .reuse/dep5                        bulk copyright declarations
  per-file headers                   SPDX-License-Identifier, per the
                                     split described above
  LICENSES/MPL-2.0.txt               code, specification surface and
                                     echidna-playground/
  LICENSES/AGPL-3.0-or-later.txt     interim only: the stale .a2ml headers
  LICENSES/CC-BY-SA-4.0.txt          documentation

Verify locally: `reuse lint`

Known gaps are recorded in docs/DEBT.adoc rather than left silent.

================================================================================

RSR / CCCP COMPLIANCE

See RSR_COMPLIANCE.adoc at repo root.

================================================================================

CONTRIBUTIONS

Contributions are licensed under the licence governing the part of the tree
they land in: MPL-2.0 for code, the machine-readable specification
surface and echidna-playground/, and CC-BY-SA-4.0 for documentation.
See .github/CONTRIBUTING.md.

By contributing, you certify that:
  1. You have the right to submit the contribution.
  2. You agree to license it under the licence governing that part of the
     tree, as set out above.
  3. You understand the contribution will be publicly available.

================================================================================

SECURITY

See SECURITY.adoc and .well-known/security.txt.
Do not disclose security issues publicly until they have been addressed.

================================================================================

CITATIONS

If you use this software in academic work, please cite:

  @software{echidna2026,
    title  = {ECHIDNA: Extensible Cognitive Hybrid Intelligence for
              Deductive Neural Assistance},
    author = {Jonathan D.A. Jewell and ECHIDNA Project Contributors},
    year   = {2026},
    url    = {https://github.com/hyperpolymath/echidna},
    license = {MPL-2.0},
  }

See CITATION.cff for machine-readable metadata and docs/CITATIONS.adoc for
the broader bibliography.

================================================================================

CONTACT

Repository:    https://github.com/hyperpolymath/echidna
Issue tracker: https://github.com/hyperpolymath/echidna/issues
Documentation: docs/ + RSR_COMPLIANCE.adoc + CLAUDE.md

================================================================================

Version: see CHANGELOG.adoc