Add opt-in AST-aware chunk boundary detection for code files using
web-tree-sitter. When enabled with `--chunk-strategy auto`, code files
(.ts, .tsx, .js, .jsx, .py, .go, .rs) are chunked at function, class,
and import boundaries instead of arbitrary text positions. Default
behavior (`regex`) is unchanged — no surprises on upgrade.
In testing on QMD's own codebase, AST mode split 42% fewer function
bodies across chunk boundaries compared to regex-only chunking.
Usage:
qmd embed --chunk-strategy auto
qmd query "search terms" --chunk-strategy auto
What's included:
- Language detection from file extension with support for TypeScript,
JavaScript (including arrow functions and function expressions),
Python, Go, and Rust
- Per-language tree-sitter queries with scored break points aligned to
the existing markdown scale (class=100, function=90, type=80, import=60)
- AST break points merged with regex break points — highest score wins
at each position, so embedded markdown (comments, docstrings) still
benefits from regex patterns
- Refactored chunking core: chunkDocumentWithBreakPoints() extracted,
mergeBreakPoints() added, async chunkDocumentAsync() wrapper for AST
- ChunkStrategy type ("auto" | "regex") threaded through
generateEmbeddings(), hybridQuery(), structuredSearch(), CLI, and SDK
- getASTStatus() health check wired into `qmd status`
- Parse failures log a warning and fall back to regex — never crash
Hardening:
- Grammar packages are optionalDependencies with pinned versions to
prevent ABI breaks from semver drift
- web-tree-sitter is a direct dependency (pinned)
- Errors are logged (not silently swallowed) for debuggability
- Tested on both Node.js and Bun (Bun is actually faster)
Testing:
- 26 unit tests (test/ast.test.ts) — all 4 languages, error handling
- 7 integration tests (test/store.test.ts) — merge, equivalence, bypass
- Standalone test-ast-chunking.mjs with 63 synthetic tests and a
real-collection performance scanner (npx tsx test-ast-chunking.mjs ~/code)
- Validated end-to-end with qmd embed + qmd query on QMD's own codebase
- Zero markdown regressions across all test paths
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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