Agent Skills & Plugins

Reusable plugins and skills for Google Antigravity, Claude Code, and OpenAI Codex.

The flagship plugin in this repo is ast-graph: a local code graph that stops coding agents from burning tokens scanning whole files and repositories by hand.

Why Use ast-graph

Left on their own, coding agents run broad grep searches and read thousands of lines of code in chunks just to find a definition, check who calls it, or figure out which tests to run. That makes sessions slow and expensive.

ast-graph builds a fast local index (.ast-graph/ast.db) for each repository so the agent gets exact line numbers, callers, upstream blast radius, and covering tests in milliseconds.

Every codebase and prompt is different, but typical results look like:

• ~70%–90% reduction in discovery tokens vs. raw grep and full-file chunk reading.
• 5x–15x fewer lines read per task: the agent reads only the exact startLine–endLine span it needs.
• Compact ~3.8 KB tool responses: summary-first outputs keep your context window clean over long sessions.
• Targeted test runs: runs only the tests linked to the changed code (vitest, pytest, go test) instead of the entire test suite.

Language Support & Limitations

• Full AST, call graph, property reads/writes, & test mapping: TypeScript/JavaScript (.ts, .tsx, .js, .mjs), Python (.py, requires python3), Go/Templ (.go, .templ), and Rust (.rs).
• Polyglot structural & cross-layer indexing: Java (.java), Kotlin (.kt, .kts), C# (.cs), Ruby (.rb), Elixir (.ex, .exs), PHP (.php), C/C++ (.c, .cc, .cpp, .h, .hpp), Swift (.swift), Zig (.zig), and WebAssembly/WIT (.wat, .wit).
• API contracts, SQL DDL, & infrastructure lineage: Protobuf (.proto), GraphQL (.graphql, .gql), SQL DDL (.sql, .sqlx — tables, columns, FKs, views, indexes), Terraform/HCL (.tf, .hcl, .tfvars), and Dockerfile (Dockerfile, Containerfile). Connects HTTP/RPC routes, schemas, SQL tables, container stages, and environment variables (scip-env global env 1.0.0 <NAME>#) across languages.
• Web & stylesheet structure: HTML, Jinja2, Vue, Svelte, Astro (delegates <script> blocks to the TS parser), and CSS.
• Section outlines only (ast_outline): Markdown, YAML, JSON, and TOML.

See plugins/ast-graph/README.md for the full support matrix and CLI usage.

Quick Install

ast-graph Plugin (Recommended)

git clone https://github.com/davenportjw/agent-skills.git
cd agent-skills/plugins/ast-graph
npm install
npm run build

# Link into Google Antigravity
ln -sfn "$(pwd)" ~/.gemini/config/plugins/ast-graph

For Claude Code:

claude plugin marketplace add davenportjw/agent-skills
claude plugin install ast-graph@davenportjw-agent-skills

Standalone Skills

To install individual skills into your agent's global skills folder:

cp -R .skills/<skill_name> ~/.gemini/config/skills/<skill_name>

Skill / Plugin	Purpose
ast-graph	Local code & cross-layer dependency graph (ast_symbol, ast_outline, ast_refs, ast_blast_radius, ast_tests_for, ast_lineage).
apple_container	Replaces Docker with Apple's native container CLI on macOS.
gcp_auth	Google Cloud authentication patterns for Identity Platform, Firebase, and Cloud Run IAM.
llm_tutor	Interactive curriculum-driven technical tutor skill.
session-journal	Tracks and summarizes active coding sessions locally in .local/sessions/.
update_documentation	Keeps project docs and tests in sync after code changes.

License

Apache-2.0