licensing

name	licensing
description	MANDATORY - Check dependency licenses before importing. Covers license compatibility (MIT, Apache, BSD, GPL), adding dependencies, bundled assets, writing original code, copyright. Triggers on go get, import, add dependency, license check, copy code.

Licensing

This project is MIT licensed.

Compatible Dependency Licenses

Before adding a dependency, check its license. These are compatible with MIT:

License	Compatible	Notes
MIT	Yes	Same license, no issues
BSD-2-Clause	Yes	Permissive
BSD-3-Clause	Yes	Permissive
ISC	Yes	Permissive (like MIT)
Apache-2.0	Yes	Permissive + patent grant
0BSD	Yes	Public domain equivalent
Unlicense	Yes	Public domain
CC0	Yes	Public domain
MPL-2.0	Yes	Weak copyleft, file-level (compatible but adds obligations)

Use With Caution

License	Notes
LGPL-2.1/3.0	Technically compatible for Go (static linking debate), but prefer alternatives
GPL-3.0 / AGPL-3.0	Technically compatible (you can use GPL code in an MIT project, but the combined work's distribution terms get complicated). Prefer MIT/Apache/BSD alternatives to keep things simple.

Incompatible (DO NOT USE)

License	Why
SSPL	Not OSI-approved, incompatible
BSL	Business Source License, time-delayed open source
Proprietary	Obviously incompatible
CC-BY-NC	Non-commercial restriction
Commons Clause	Commercial restriction
No license	Treat as proprietary — do not use

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Checking Dependency Licenses

Go Dependencies

# List all dependencies with licenses
go-licenses report ./... 2>/dev/null

# Or manually check go.mod imports
go list -m -json all | jq -r '.Path'
# Then check each on pkg.go.dev or GitHub

Before Adding a Dependency

1. Check the LICENSE file in the repo
2. Verify it's in the compatible list above
3. If unclear, check SPDX identifier: https://spdx.org/licenses/

Planned Dependencies

Key dependencies and their licenses:

• github.com/yuin/goldmark — MIT ✓
• github.com/yuin/goldmark-highlighting — MIT ✓
• go.abhg.dev/goldmark/mermaid — MIT ✓
• github.com/alecthomas/chroma/v2 — MIT ✓

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Writing Original Code

The Rule

Learn from other projects. Write your own code.

When studying how another project implements something:

1. Understand the concept — What problem does it solve? What's the approach?
2. Close the source — Don't have it open while writing
3. Write from understanding — Implement based on your mental model
4. Make it better — Your version should be at least as good, preferably superior

What's NOT Allowed

// WRONG: Copied from github.com/other/project
func ParseConfig(data []byte) (*Config, error) {
    // [copied code]
}

// WRONG: "Adapted" (minor variable renames)
func ParseConfiguration(input []byte) (*Configuration, error) {
    // [same logic, different names]
}

What IS Allowed

// RIGHT: Studied how X project handles URL rewriting,
// implemented our own version with better error messages
// and support for relative path resolution.
func RewriteRelativeURLs(doc []byte, baseURL string) []byte {
    // [original implementation]
}

Gray Areas

Situation	Guidance
Standard patterns (middleware, handlers)	OK — these are universal idioms
Algorithm from a paper/spec	OK — implement the spec, not someone's code
Small utility (max, min, clamp)	OK — too simple to be copyrightable
Copied struct layout	Risky — restructure based on your needs
Copied test cases	Risky — write your own test scenarios

When In Doubt

1. Can you explain it without looking at the source?
2. Would your implementation differ if you'd never seen theirs?
3. Are you copying structure or just learning a concept?

If yes to all three, you're probably fine.

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Bundled Assets

Static assets embedded in the binary must have compatible licenses.

Current bundled assets:

• mermaid.js — MIT
• github-markdown-css — MIT

When adding bundled assets:

1. Verify license compatibility
2. Note version in Makefile (pinned with SHA-256 verification)

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License Headers

Go files do not require license headers — the root LICENSE file covers everything. Optional header for key files:

// Copyright 2026 air-gapped
// SPDX-License-Identifier: MIT