add-license-header

name	add-license-header
description	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."

Follow this procedure exactly.

1. Identify targets. From the user's request, determine the file(s) 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 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 of the file. For files missing 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 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).