Copyright Headers

All source files in the HelixScreen project must include an SPDX license identifier.

SPDX License Identifier (Required)

All source files must include this header at the top of the file:

C/C++ Files (.c, .cpp, .h, .hpp)

GPL-3.0-or-later

// Copyright (C) 2025-2026 356C LLC

Python Files (.py)

GPL-3.0-or-later

# Copyright (C) 2025-2026 356C LLC

Bash Scripts (.sh)

#!/usr/bin/env bash
# Copyright (C) 2025-2026 356C LLC
# SPDX-License-Identifier: GPL-3.0-or-later

XML Files (.xml)

<?xml version="1.0"?>
<!-- Copyright (C) 2025-2026 356C LLC -->
<!-- SPDX-License-Identifier: GPL-3.0-or-later -->

Why SPDX?

SPDX (Software Package Data Exchange) identifiers are:

• Machine-readable: Automated tools can instantly detect licenses
• Industry standard: Used by Linux kernel, LLVM, and major open source projects
• Legally equivalent: SPDX + LICENSE file = complete legal notice
• Concise: 2 lines instead of 20+ lines of boilerplate per file

The full copyright notice and GPL license text are in the COPYRIGHT and LICENSE files at the repository root.

Adding Headers to New Files

When creating new source files:

1. Add the appropriate SPDX header at the top (see examples above)
2. Preserve special first lines (shebang #!/usr/bin/env, XML declaration <?xml)
3. Leave a blank line after the header before code begins

Batch Application

To add SPDX headers to multiple files:

# Dry-run (shows what would be changed)
./scripts/add-spdx-headers.sh

# Apply to all source files
./scripts/add-spdx-headers.sh --apply

# Apply to specific files
./scripts/add-spdx-headers.sh --apply src/myfile.cpp include/myheader.h

# Verbose output with diffs
./scripts/add-spdx-headers.sh --verbose

The script automatically:

• Detects file type (C/C++, Python, Bash, XML)
• Preserves shebangs and XML declarations
• Removes old verbose copyright boilerplate
• Adds clean SPDX headers
• Skips files that already have SPDX identifiers

Verification

To check that all files have SPDX identifiers:

# Run quality checks (includes SPDX verification)
./scripts/quality-checks.sh

# Manual check for missing SPDX in C/C++ files
grep -L "SPDX-License-Identifier: GPL-3.0-or-later" src/*.cpp include/*.h

# Check specific file
head -5 src/main.cpp | grep SPDX

Pre-commit Hook

The quality checks script runs automatically via pre-commit hook if configured:

# Install pre-commit hook
cp scripts/pre-commit .git/hooks/pre-commit
chmod +x .git/hooks/pre-commit

This ensures all committed files have proper SPDX headers.

Full Copyright Notice

For the complete copyright and license information, see:

• COPYRIGHT - Comprehensive copyright notice
• LICENSE - Full GPL-3.0-or-later license text

Third-Party Code

Third-party libraries in lib/ retain their original licenses and copyright notices. See individual library directories for their license information.

Notes

• Year: Update to current year for new files (e.g., 2026, 2027)
• No verbose headers: SPDX identifiers replace verbose GPL boilerplate
• Machine-readable: Tools like reuse can verify SPDX compliance
• Standards compliant: Follows REUSE 3.0 best practices