C Systems & Native Code

Covers C11 and later for libraries, systems code, and native extensions. For C++ (RAII, templates, move semantics), see the ia-cpp-systems skill.

Working rules

• Preserve the repository's sanctioned idioms and ABI; do not turn a scoped fix into a restyle.
• State ownership, check fallible calls, validate public boundaries, and assert internal invariants.
• Bound traversal of external input and check sizes before allocation or narrowing.
• Choose helpers only when they name a concept, own an error, or isolate a side effect.
• Verify the actual rebuilt artifact; use instrumented tests for safety and representative release builds for performance.

Repo conventions outrank this skill

Read the repo's AGENTS.md/CLAUDE.md, its public headers, and two adjacent .c files before writing anything. Where they conflict with the rules below, they win, and the diff carries no note about it.

This gate is load-bearing. Established C codebases sanction idioms these rules would otherwise flag: