MAXI Format

Full language support for MAXI (.maxi / .mxs) files in Visual Studio Code.

MAXI is a compact, schema-driven serialization format designed to minimize token usage in LLM contexts and API communications while remaining human-readable.

Features

Syntax Highlighting

Every MAXI construct gets a distinct, meaningful color:

Semantic Highlighting

The language server enriches data records with type-aware token colors that the grammar alone cannot provide:

Hover Tooltips

Hover over any token to see contextual information:

• Field value → field name and type, e.g. role · enum[admin, editor, user]
• Object reference (bare id in an object-typed field) → the full resolved record it points to
• Record alias (U at the start of a data line) → the full resolved type definition with all fields
• Type alias in schema → resolved field list including inherited fields
• Annotation-aware display: str@date shows date (YYYY-MM-DD), str@email shows email address

Go to Definition

Press F12 on:

• Alias in a data record → jumps to the type definition in the schema section
• Parent type in <Parent> → jumps to the parent's definition
• Bare id in an object-typed field → jumps to the referenced record
• Works across files — if the type is defined in an @schema: imported .mxs file, VS Code opens it

Find All References

Press Shift+F12 on any type alias to see every data record that uses it listed in the References panel.

Rename

Press F2 on a type alias to rename it across the entire document — the type definition line and every data record are updated atomically.

Diagnostics

Red and yellow squiggles for schema violations:

Completion

Ctrl+Space inside a data record:

• enum field → list of valid enum values
• bool field → 1, 0, true, false
• Object-typed field → IDs of all known records of that type in the current file
• Start of a record line → all type aliases defined in the schema
• @schema:directive → .mxs files in the same directory
• str@date field → today's date in YYYY-MM-DD
• str@datetime field → current datetime in ISO 8601

MAXI at a Glance

@maxi:1.0.0
@version:2.0.0

# Type alias : Type name ( field | field:type | field:type(constraints) )
U:User(
  id:int(id)         |
  name:str(!,>=1)    |
  email:str@email(!) |
  role:enum[admin,editor,viewer]=viewer |
  active:bool=1
)

O:Order(
  id:int(id)  |
  user:U      |
  total:decimal(>=0)
)

###

U(1|Alice|[email protected]|admin|1)
U(2|Bob|[email protected]|viewer|1)
O(100|1|149.99)
O(101|2|29.00)

• U and O are short type aliases used in data records
• Fields are positional — names are declared once in the schema
• ### separates the schema section from the data section
• External schemas can be imported with @schema:path/to/file.mxs

Installation

From the Marketplace

Search for MAXI Format in the VS Code Extensions panel and click Install.

From Source (Development)

git clone https://github.com/maxi-format/maxi-vscode
cd maxi-vscode
npm install

Press F5 in VS Code to launch the Extension Development Host.

Build a .vsix Package

npm install -g @vscode/vsce
vsce package

Then install via Extensions: Install from VSIX… in the VS Code command palette.

File Associations

The extension activates automatically for:

Related

• MAXI Specification — the full format spec
• MAXI schema implementations see here

License

Released under the MIT License.