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

Mojo is young and fast-moving. The dominant failure mode for agents is emitting 2023-2024-era syntax that now warns or fails to compile. This plugin ships an always-on stale-to-current version map plus focused guidance for fundamentals, performance, and GPU - so agents target the current language (Mojo v1.0.0b1), not their training data.

• Embeds a stale-to-current version map agents apply on every Mojo task: def not fn, var/read/mut not owned/borrowed/inout, @fieldwise_init not @value, synthesized __init__(copy=)/__init__(take=) not __copyinit__/__moveinit__, TileTensor/LayoutTensor not NDBuffer, TestSuite not the removed mojo test command.
• Core rules for idiomatic structs, traits, ownership, comptime metaprogramming, and typed error handling.
• Performance guidance: SIMD, vectorize/parallelize/elementwise, @always_inline, LayoutTensor, benchmarking.
• GPU guidance: DeviceContext, kernels, the thread/block/grid model, shared memory, barrier(), warps, occupancy (NVIDIA / AMD / Apple).
• Links to current upstream docs (mojolang.org) for depth, rather than bundling a deep-dive guide that would drift.

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.

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.

skills/mojo/SKILL.md     the skill (version map + core rules + workflow + doc links)
.claude-plugin/          Claude Code plugin + marketplace manifests
.codex-plugin/           Codex plugin manifest

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.

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

MIT