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.
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.
npx skills add rmyndharis/antigravity-skills --skill c4-contextgit clone --depth 1 https://github.com/rmyndharis/antigravity-skillsWrote 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.
[](https://agentmods.dev/skills/rmyndharis/antigravity-skills/c4-context)<a href="https://agentmods.dev/skills/rmyndharis/antigravity-skills/c4-context"><img src="https://agentmods.dev/badge/skills/rmyndharis/antigravity-skills/c4-context/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.
<a href="https://agentmods.dev/skills/rmyndharis/antigravity-skills/c4-context"><img src="https://agentmods.dev/badge/skills/rmyndharis/antigravity-skills/c4-context.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00061 | $0.01117 |
| Opus 5 | $0.00030 | $0.00558 |
| Sonnet 5 | $0.00012 | $0.00223 |
| Haiku 4.5 | $0.00006 | $0.00112 |
Grade A, and why
c4-context 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.
Copies of this mod
1 near-identical copy found in the catalogue:
- c4-context — 100% identical, 1 lines differ
How it starts
The opening of the file, as written. The whole thing — 150 lines — stays where its author put it; the contents beside it link to each section on GitHub.
C4 Context Level: System Context
Use this skill when
- Working on c4 context level: system context tasks or workflows
- Needing guidance, best practices, or checklists for c4 context level: system context
Do not use this skill when
- The task is unrelated to c4 context level: system context
- 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.
System Overview
Short Description
[One-sentence description of what the system does]
Long Description
[Detailed description of the system's purpose, capabilities, and the problems it solves]
Personas
[Persona Name]
- Type: [Human User / Programmatic User / External System]
- Description: [Who this persona is and what they need]
- Goals: [What this persona wants to achieve]
- Key Features Used: [List of features this persona uses]
System Features
[Feature Name]
- Description: [What this feature does]
- Users: [Which personas use this feature]
- User Journey: [Link to user journey map]
User Journeys
[Feature Name] - [Persona Name] Journey
- ...
[External System] Integration Journey
- ...
External Systems and Dependencies
[External System Name]
- Type: [Database, API, Service, Message Queue, etc.]
- Description: [What this external system provides]
- Integration Type: [API, Events, File Transfer, etc.]
- Purpose: [Why the system depends on this]
System Context Diagram
[Mermaid diagram showing system, users, and external systems]
Related Documentation
## Context Diagram Template
According to the [C4 model](https://c4model.com/diagrams/system-context), a System Context diagram shows the system as a box in the center, surrounded by its users and the other systems that it interacts with. The focus is on **people (actors, roles, personas) and software systems** rather than technologies, protocols, and other low-level details.
Use proper Mermaid C4 syntax:
```mermaid
C4Context
title System Context Diagram
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.
- 10d ago First seen · 150 lines · 61 tokens per session scan A 6c373fb6530e
c4-context is a skill published in the GitHub repository rmyndharis/antigravity-skills (1,517 stars, last pushed 1mo ago), licensed MIT. It adds 61 tokens to every session and 1,117 once invoked, about $0.0003 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.
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code-review
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project-context-primer
Run this skill at the very start of any new conversation or agent session before writing a single line of code. It loads the project's architectural decisions, conventions, known gotchas, and current task status so the agent operates with full context — not as a blank slate.
test-driven-execution
Before writing any implementation code, define the acceptance criteria and test cases that the code must satisfy. Agents then write code to pass these tests — not to match a vague description. Eliminates "it works on my machine" and "I think this is what you wanted" outcomes.
idea-validator
Structured validation framework that scores product ideas. Use when evaluating problem severity, willingness-to-pay, or founder-market fit. For market intelligence, see market-research.