# Add License Header

> Add the project's canonical SPDX license header to source files that are missing one. Use when asked to add a license header to a file or directory, e.g. "add the license header to src/foo.ts" or "make sure every file in src/ has our license header."

- Skill: `sociotechnica-org/add-license-header-3` (Agent Skill)
- Install (CLI): `npx skillmds@latest add sociotechnica-org/add-license-header-3`
- Raw SKILL.md: https://api.skillmd.com/api/skills/sociotechnica-org/add-license-header-3/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: sociotechnica-org (https://skillmd.com/u/sociotechnica-org)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/sociotechnica-org/add-license-header-3

---


1. **Determine target files.** From the user's request, resolve the set of
   files to process -- either a single path or every source file under a
   given directory.

2. **Check each file for an existing header.** Read the first 20 lines of
   each target file and look for the string `SPDX-License-Identifier`.

3. **Skip files that already have a header.** If `SPDX-License-Identifier`
   appears in the first 20 lines, do not touch that file. Never add a
   second header to a file that already has one.

4. **Insert the header at the very top.** For files that lack a header,
   insert these exact two lines as the first two lines of the file, above
   all existing content (including shebangs, comments, or blank lines):
   ```
   // SPDX-License-Identifier: Apache-2.0
   // Copyright (c) 2026 Acme Corp
   ```
   The header must always be the very first thing in the file -- never
   insert it after existing content.

5. **Report results.** List which files were changed and which were skipped
   (already had a header).