# 1. Use nvim-treesitter `highlights.scm` as behavioral capture source

**Date:** 2026-07-03

**Status:** Accepted

## Context

We need a universal source of behavioral code tokens (function calls, references, definitions) across multiple programming languages. Options:

- **`tags.scm`** (nvim-treesitter): Purpose-built for symbol tagging. Covers definitions and references.
- **`highlights.scm`** (nvim-treesitter): Built for syntax highlighting. Covers a wider range of tokens including keywords, operators, and built-ins.
- **Custom per-language queries**: Write and maintain our own query files for each language.

We need tokens that represent *what the code does at runtime* — not just structure.

## Decision

Use nvim-treesitter `highlights.scm` as the capture source for all 10 languages.

We filter captures to a `BEHAVIORAL_PREFIXES` set: `definition.`, `reference.`, `keyword.`, `function`, `attribute`, `constructor`, `label`, `type.definition`, `module`.

For Kotlin, use the `ts-kotlin` (fwcd fork) bundled `highlights.scm` instead of nvim-treesitter's, because nvim-treesitter's Kotlin query references a duplicate `annotation` node type that doesn't exist in the grammar.

## Consequences

**Positive:**
- `highlights.scm` covers 4 out of 5 behavioral capture types that `tags.scm` misses, across all 10 languages.
- No per-language custom code or adapters needed.
- Community-maintained queries stay fresh with language evolution.
- Same query files work for both parsing and tokenizing.

**Negative:**
- `highlights.scm` includes non-behavioral captures (comments, punctuation, operators) — we filter these out.
- Some nvim-treesitter queries use `#set!` directives (`#set! priority`, `#eq?`) that `py-tree-sitter` doesn't support. These patterns are removed in the bundled copies under `queries/`.
- Kotlin requires a separate grammar package (`ts-kotlin`) because the nvim-treesitter Kotlin grammar is incompatible.

## Alternatives Considered

- **`tags.scm`**: Cleaner signal-to-noise ratio, but misses `function`, `attribute`, `constructor`, `module` captures that are essential for behavioral understanding.
- **Custom queries**: Would give full control but require per-language maintenance — violates our universal-preprocessor constraint.
