No license, no permission

Goal#

Understand what copyright gives an author by default, why a public repository is not open source on its own, what a license actually does, and how to add one properly: the exact text, a real copyright line and the right identifier.

The case#

uv run python -m nest run 1

nest scan case01_no_license/

LICENSE               (none)
README                (no License section)
pyproject.toml        (none)
notices               (none)

  ✗ no LICENSE file: the code is 'all rights reserved' and nobody may reuse it
  ✗ README has no License section
  ✗ pyproject.toml declares no license

Robin Vale wrote Starling, a tiny command-line notebook, and put it on GitHub. The README says "Starling is open source, so use it however you like!" Nothing else does. Open lab/cases/case01_no_license/ and look for a license. There is none.

Copyright is automatic#

In almost every country, the moment you write code, you own the copyright in it. You do not register anything or add a © sign. Copyright gives the author, and only the author, the right to copy the work, change it and share it.

So the default for any code is all rights reserved. Nobody else may copy, modify or redistribute it, even if they can see it.

Public is not open source#

Publishing a repository lets people read the code. GitHub's terms of service add a little more: other users may view and fork a public repository on GitHub. That is all. They may not copy the code into their own project, ship it in a product or publish a changed version elsewhere.

A sentence in a README such as "use it however you like" does not fix this. It is vague: may people sell it, change it, remove your name? Lawyers at the companies who might use Starling will not guess, and careful developers will not touch it.

What a license does#

A license is the author giving permission in advance, in writing, on conditions everyone can read. Open source licenses give everyone the same permission: use, copy, change and share, including commercially. They differ in what they ask in return.

There is no wrong answer here, only a choice. Robin wants MIT: short, well known and easy to follow.

The exact text, not from memory#

Tools and lawyers recognise a license by its exact words. Never type one from memory or "tidy it up". Get the canonical text:

gh api licenses/mit --jq .body

You can also copy it from choosealicense.com or the SPDX license list. The case uses the same text, in lab/nest/texts/MIT.txt.

The copyright line#

The MIT text starts with a template line: Copyright (c) [year] [fullname]. Fill it in with the year the code was first published and the name of whoever owns it, then leave every other word alone.

• Whose name? The author's, or their employer's if they wrote it as part of their job. For a project with many contributors, Robin Vale and contributors is common.
• Which year? The year of first publication. Some projects write a range, such as 2024-2026. Both are fine. A missing year is not.

The identifier#

Every license has a short, exact name from the SPDX list: MIT, Apache-2.0, GPL-3.0-only. Package managers read it from the manifest. In pyproject.toml it is one line under [project]:

license = "MIT"

Chapter 02 is all about these identifiers.

Fix the case#

In lab/cases/case01_no_license/:

1. Create LICENSE with the MIT text, and fill in the copyright line for Robin Vale and 2026.
2. Add license = "MIT" to pyproject.toml, under [project].

Check it works#

uv run python -m nest check 1

  PASS  a LICENSE file at the root of the project
  PASS  LICENSE is the MIT license, word for word
  PASS  its copyright line names Robin Vale and a year
  PASS  pyproject.toml declares license = "MIT"

Then run nest run 1 again. The scan now has one complaint left: the README has no License section. Chapter 02 deals with it.

Exercise#

Add a sentence to the end of the MIT text in your fix, such as "Not for commercial use.", and run the check. Why does a single extra sentence mean the file is no longer the MIT license? Then remove it again.

More to try

• Run uv run python -m nest scan .. from lab/ to scan this workshop itself, then scan a repository of your own.
• Find a project you use that has no license. Open an issue that asks, politely, which license the author intends.