TOML

The TOML server starts the first time you open a .toml file, Pipfile, Cargo.lock, .cargo/config, poetry.lock or uv.lock, and stops when none remain open.

TOML files are checked by Tombi. It underlines syntax errors and values that do not match the file’s JSON Schema, and the schema also drives completions and hover documentation for keys and values. You also get the document outline, folding, go-to-definition and quick fixes.

Schemas come from Settings > Schemas, the same mappings JSON and YAML files use. These files have built-in schemas from SchemaStore:

pyproject.toml, including tool tables such as [tool.ruff] and [tool.uv]
Cargo.toml and .cargo/config.toml
rust-toolchain.toml
ruff.toml and .ruff.toml
uv.toml
rustfmt.toml and .rustfmt.toml

Turn a built-in schema off to stop checking files against it, or add your own mapping: a glob ending in .toml and the schema’s URL or local path. Your mappings take precedence over the built-in ones for the same file. A TOML glob with wildcards, such as config/*.toml, applies only to files inside the project, and its * also matches files in subfolders. Schemas are downloaded when a file first needs them and cached for a day.

A #:schema comment at the top of a file picks its schema directly, by URL or by a path relative to the file, and takes precedence over the settings:

#:schema ./schemas/app.schema.json
name = "demo"

Projects that configure Tombi themselves, with a tombi.toml or .tombi.toml file or a [tool.tombi] table in pyproject.toml, use that configuration instead of the Schemas settings, so the editor agrees with the tombi command line. A ~/.config/tombi/config.toml of your own does the same for every project. Formatting stays with format on save.

TOML

See also