tools_semantic_tokens

A local web viewer for BAML semantic tokens — the LSP-style, type-aware classification produced by baml_lsp2_actions::semantic_tokens. It is the semantic-token analog of typescript2/pkg-grammar's grammar-preview app, but because semantic tokens are computed by the Rust compiler (not a portable TextMate grammar) this tool embeds the compiler directly instead of running in the browser.

cargo run -p tools_semantic_tokens
# semantic-tokens viewer  ->  http://127.0.0.1:4319

It opens a browser (pass --no-open to skip) with:

• Fixtures — every *.baml under crates/baml_lsp2_actions_tests/test_files/semantic_tokens/. Each is shown side-by-side: Current (live tokens) vs Expected snapshot (the committed //- semantic_tokens block), with changed/added/removed tokens underlined and a per-fixture diff badge in the sidebar. Accept snapshot rewrites the fixture exactly as UPDATE_EXPECT=1 cargo test would.
• Scratchpad — paste arbitrary BAML and see live tokens (no snapshot).

Hover any token to inspect its type; the legend maps every token type to its color.

Flags

• --port <N> preferred port (falls back to the next free port; default 4319)
• --fixtures-dir <DIR> browse a different directory of *.baml fixtures
• --no-open don't launch a browser

How it works

The tool reuses the inline-assertion test harness (baml_lsp2_actions_tests::{parser, runner, updater}) so the token output, the parsed expectations, and "accept" are identical to the Rust tests — there is no second implementation to drift. Rendering assumes ASCII source (token positions are byte offsets); the committed fixtures are ASCII.