mojo

A skill that teaches any coding agent to write idiomatic, correct, performant, current Mojo (Modular's language).

Mojo is young and fast-moving, and most Mojo in model training data predates 1.0. The common failure is code that looks right from memory and no longer compiles. This plugin ships an old-to-current map for Mojo 1.1 plus short, verified references, so agents target the current language rather than their training data.

What it does

• An old-to-current map applied on every Mojo task: def not fn, var/imm/mut not owned/read/inout, comptime not alias or @parameter if, unified closures and lambda, Pointer with unsafe_ operations not UnsafePointer, Array/StringSpan renames, max.gpu not std.gpu, TestSuite not mojo test, mojo precompile not mojo package.
• Rules that hold across tasks: explicit copies and moves, struct and trait model, typed raises, explicit numeric conversion, grapheme-aware strings, interior origins.
• References for memory and CPU performance (pointers, allocation, SIMD, vectorize), GPU kernels (DeviceContext, TileTensor, warps, shared memory) and Python interop (bindings, extension modules).
• A toolchain check first: when the installed mojo is older or newer than 1.1, the compiler wins.

Installation

claude plugin marketplace add agent-sh/mojo
claude plugin install mojo

Or add it through the agentsys marketplace alongside the rest of the agent-sh ecosystem.

Usage

The skill activates automatically on Mojo work. Triggers include:

write a Mojo struct for a 3D vector with SIMD ops
port this Python function to Mojo
is this idiomatic Mojo?
write a GPU vector-add kernel in Mojo
why is my Mojo parallelize loop slow?

It does not activate for Python, Rust, C++, or Modular MAX serving/deployment config.

Layout

skills/mojo/SKILL.md     the skill (version map, core rules, doc links)
skills/mojo/references/  memory and performance, GPU, Python interop
.claude-plugin/          Claude Code plugin + marketplace manifests
.codex-plugin/           Codex plugin manifest

Development

agnix .                  # validate skill + manifests (zero errors required)
claude plugin validate . # validate marketplace and plugin manifests

Mojo guidance is grounded in current upstream docs at mojolang.org/docs, not model memory - re-verify any stdlib API outside stabilized-API markers against the installed toolchain.

Related Plugins

• skill-curator - for writing and reviewing skills
• agnix - the linter that validates this plugin
• Part of the agent-sh ecosystem

License

MIT