Add Mojo language support

[Tokarzewski]

Language

Mojo (Modular) — Python-superset systems language for AI/ML infra.

Grammar

lsh/tree-sitter-mojo
Forked from tree-sitter-python. MIT license, ABI 15, C scanner (no libstdc++).

• Pinned commit: 33193a99afe6
• License: MIT (vendored LICENSE byte-verified against upstream)
• ABI: 15 (compatible with current runtime ceiling)
• Scanner type: C (no C++ dependency)
• Registries: Not in nvim-treesitter or Helix — community grammar

Integration scope

• CBM_LANG_MOJO enum, grammar_mojo.c wrapper, extraction spec in lang_specs.c
• Extensions: .mojo, .🔥
• Spec reuses py_* arrays (node types mirror Python); overrides only class types
• Mojo-specific: fn/def → function_definition, struct/class → class_definition, trait/__extension → trait_definition/extension_definition (Interface label), alias → captured via assignment

Verification

Tested against NuMojo (135 files) and EnergyPlusMojo + 7,354 generated files — 166K+ nodes, no crashes.

[DeusData]

Thanks for writing this up and for keeping the grammar provenance details concrete. Triage: this is the Mojo language-support tracker under parsing/language coverage.

The maintainer-side grammar blocker is now resolved: #744 vendored lsh/tree-sitter-mojo from a pinned commit after MIT license/provenance review and static security review, and it is merged into main.

For the remaining integration work, #502 can now rebase on current main, drop any local vendored grammar copy, keep the Mojo language integration changes, and clean up DCO/sign-off. Once that is done, we can review the actual extractor/spec behavior against fixtures.

[DeusData]

Closing this tracking issue because the maintainer-side Mojo grammar request is now resolved by #744, which vendored the grammar after license/provenance/security review and merged it into main.

The remaining Mojo language integration work should continue on #502: rebase on current main, drop any local vendored grammar copy, keep the integration changes, and fix DCO/sign-off. Status and review for that work should stay on #502.