License ADR

reference/decisions/ADR-002-license.md

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+# ADR-002: Use the MIT License
+
+* **Status:** Accepted
+* **Date:** 2026-07-29
+
+## Context
+
+The project is intended to be an open educational and engineering reference for designing OTA update systems on embedded Linux.
+
+The repository may contain:
+
+* documentation;
+* diagrams;
+* source code;
+* scripts;
+* configuration examples;
+* reference implementations;
+* test utilities;
+* failure-injection experiments.
+
+The license should allow engineers to study, modify, reuse, and adapt the material in both personal and commercial projects.
+
+The license should also be familiar, permissive, and easy to understand. The project does not require derivative works to remain open source.
+
+## Decision
+
+The repository will be licensed under the MIT License.
+
+The license will apply to the repository content unless a specific file or third-party component explicitly states otherwise.
+
+A standard `LICENSE` file containing the MIT License text will be included at the repository root.
+
+## Alternatives Considered
+
+### Apache License 2.0
+
+Apache 2.0 is a permissive license that includes an explicit patent grant and patent retaliation provisions.
+
+It was not selected because the project is currently an educational reference design rather than a large infrastructure framework or commercially governed software platform.
+
+The additional legal complexity does not currently provide enough practical benefit over MIT.
+
+### GNU General Public License
+
+The GPL would require derivative works distributed under certain conditions to remain under the same license.
+
+It was not selected because the project is intended to encourage broad reuse, including adoption of ideas and code in commercial embedded products.
+
+A copyleft requirement could discourage some companies or engineers from using the examples.
+
+### BSD 2-Clause or BSD 3-Clause License
+
+The BSD licenses are permissive and would also be suitable for the project.
+
+They were not selected because MIT is more familiar to many readers, concise, and already consistent with other projects maintained by the author.
+
+### No Explicit License
+
+Without a license, the repository would remain protected by copyright by default and other people would not have clear legal permission to reuse the material.
+
+This would conflict with the educational and open-source goals of the project.
+
+## Consequences
+
+### Positive
+
+* The project can be used in open-source and commercial environments.
+* Engineers can copy, modify, and redistribute examples.
+* The license is short and widely understood.
+* The project remains easy to adopt.
+* The license is consistent with the author’s other open-source repositories.
+* Attribution and preservation of the license notice are still required.
+
+### Negative
+
+* Modified versions are not required to remain open source.
+* Improvements may be used commercially without being contributed back.
+* The license does not include the explicit patent language provided by Apache 2.0.
+* The software is provided without warranty or liability protection beyond the license terms.
+
+## Notes
+
+The repository is a reference design and educational project.
+
+The MIT License permits reuse but does not imply that the implementation is production-ready, certified, secure for every deployment, or suitable for safety-critical systems.
+
+These limitations should also be explained in the repository README.