c-pro

c-pro is a skill for Claude Code, Codex from rmyndharis/antigravity-skills. It costs 47 tokens per session (342 once invoked), scanned A, original, MIT.

Guidance for writing C programs, a language often used for operating systems, embedded devices, and other software where memory and speed matter. It covers memory ownership, pointers, system calls, threads, debugging, and tests.

In plain words
What is it for?
Use it when building or debugging C software, including embedded programs, kernel modules, and performance-sensitive code. It can guide code structure, Makefiles, tests, profiling, and tools such as Valgrind, GDB, and clang-tidy.
Why use it?
It helps prevent memory leaks, invalid memory use, unchecked errors, and unnecessary slowdowns. It also provides checks and build settings for finding problems earlier.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it when building or debugging C software, including embedded programs, kernel modules, and performance-sensitive code. It can guide code structure, Makefiles, tests, profiling, and tools such as Valgrind, GDB, and clang-tidy.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/rmyndharis/antigravity-skills/c-pro
About the project

Antigravity Skill Vault is a collection of reusable Agent Skills for Google Antigravity, covering software development, operations, security, and business work. It is for people who want Antigravity agents to follow specialized expertise, personas, and structured workflows. The catalogue skills are entries from this collection.

rmyndharis/antigravity-skills · 1,517 stars · on GitHub

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add rmyndharis/antigravity-skills --skill c-pro
Clone the repo
git clone --depth 1 https://github.com/rmyndharis/antigravity-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for c-pro

README.md
[![agentmods](https://agentmods.dev/badge/skills/rmyndharis/antigravity-skills/c-pro/github.svg)](https://agentmods.dev/skills/rmyndharis/antigravity-skills/c-pro)
Your own site
<a href="https://agentmods.dev/skills/rmyndharis/antigravity-skills/c-pro"><img src="https://agentmods.dev/badge/skills/rmyndharis/antigravity-skills/c-pro/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for c-pro

Your own site · 80×15
<a href="https://agentmods.dev/skills/rmyndharis/antigravity-skills/c-pro"><img src="https://agentmods.dev/badge/skills/rmyndharis/antigravity-skills/c-pro.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 47 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 342 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Memory Poisoning · line 48
    Skill manipulates agent memory, state, or stored context. Memory corruption can alter personality, override safety rules, or cause unpredictable behavior.
    Fix: Protect agent memory and state from modification by untrusted content. Use read-only memory for critical instructions and validate all state changes.
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00047 $0.00342
Opus 5 $0.00023 $0.00171
Sonnet 5 $0.00009 $0.00068
Haiku 4.5 $0.00005 $0.00034

Measured 10d ago against content hash d4733fabc0f1, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

c-pro scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

  • c-pro — 97% identical, 1 lines differ
skills/c-pro/SKILL.md · 56 lines

What it actually says

Use this skill when

  • Working on c pro tasks or workflows
  • Needing guidance, best practices, or checklists for c pro

Do not use this skill when

  • The task is unrelated to c pro
  • You need a different domain or tool outside this scope

Instructions

  • Clarify goals, constraints, and required inputs.
  • Apply relevant best practices and validate outcomes.
  • Provide actionable steps and verification.

You are a C programming expert specializing in systems programming and performance.

Focus Areas

  • Memory management (malloc/free, memory pools)
  • Pointer arithmetic and data structures
  • System calls and POSIX compliance
  • Embedded systems and resource constraints
  • Multi-threading with pthreads
  • Debugging with valgrind and gdb

Approach

  1. No memory leaks - every malloc needs free
  2. Check all return values, especially malloc
  3. Use static analysis tools (clang-tidy)
  4. Minimize stack usage in embedded contexts
  5. Profile before optimizing

Output

  • C code with clear memory ownership
  • Makefile with proper flags (-Wall -Wextra)
  • Header files with proper include guards
  • Unit tests using CUnit or similar
  • Valgrind clean output demonstration
  • Performance benchmarks if applicable

Follow C99/C11 standards. Include error handling for all system calls.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 10d ago First seen · 56 lines · 47 tokens per session scan A d4733fabc0f1

Subscribe to this mod's changes

c-pro is a skill published in the GitHub repository rmyndharis/antigravity-skills (1,517 stars, last pushed 1mo ago), licensed MIT. It adds 47 tokens to every session and 342 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.