LSP / IDE

craftgo ships its own language server, craftgo-lsp. It powers completion, hover, diagnostics, go-to-definition, and formatting for .craftgo files.

The only first-party editor integration today is the VS Code extension. Other editors that speak LSP can spawn the binary directly, but they are not officially supported and may need extra setup for syntax highlighting (no shipped grammar package outside the VS Code extension).

Install the LSP

go install github.com/craftgodotdev/craftgo/cmd/craftgo-lsp@latest

The binary lands in $GOBIN (or $GOPATH/bin). Make sure the directory is on your PATH.

VS Code

Install the craftgo extension from the marketplace. The extension auto-spawns craftgo-lsp for any file with the .craftgo extension. Syntax highlighting, snippets, and the language server all activate together.

Verify it works:

1. Open a .craftgo file
2. Type @ inside a field
3. The completion popup should list valid decorators

If completion stops working after you upgrade craftgo, restart the language server:

Cmd+Shift+P -> craftgo: Restart Language Server

The LSP runs as a separate binary; rebuilding craftgo's source does not refresh the running server until you reinstall the binary and restart it.

Building the VS Code extension from source

git clone https://github.com/craftgodotdev/craftgo
cd craftgo/extensions/vscode
npm install
npm run package
code --install-extension craftgo-*.vsix

Reload the VS Code window after install.

Features

Completion

Type @ inside a field to see decorators valid for the field's type:

type User {
    age int @|
    //      ^ shows: required, min, max, range, positive, negative, multipleOf, default, ...
}

The list is filtered by the field's primitive: @length only appears on string fields, @minItems only on arrays.

Smart argument completion

Inside @default(...) on an enum field, only the enum's values are suggested:

enum Status { Active  Inactive  Pending }

type User {
    status Status @default(|)
    //               ^ shows: Active, Inactive, Pending
}

Inside @timeout(...) or @maxBodySize(...), common values appear as presets. Once you type a number, the matching unit suffixes get offered:

@timeout(10|)
//        ^ shows: 10ms, 10s, 10m, 10h

Hover

Hover over an identifier to see its declaration and doc comment. Works on:

• Decorators (@length, @format, @default, ...) - shows purpose, allowed sites, argument shape
• Type references inside fields - shows the type's declaration
• Enum values inside @default(EnumValue) - shows the enum value's source

Diagnostics

Errors appear inline as you type:

• decorator/unknown - @nope is not registered
• decorator/placement - decorator appears at the wrong site (@prefix on a field)
• decorator/conflict - incompatible decorator pair (@sensitive with @length)
• decorator/default-needs-optional - @default on a non-optional field (warning; format auto-fixes)
• decorator/typemismatch - validator on the wrong primitive (@length on int)
• field/duplicate - same field name twice
• service/path-conflict - two methods on the same verb + path
• enum/value-collision - two values produce the same Go constant

Go-to-definition

Cmd+click (or gd in vim-mode) on a type reference jumps to its declaration. Works across files in the same package and across packages via import.

Format

The craftgo fmt CLI rewrites a file in canonical form: aligned field columns, consistent decorator spacing, sorted imports. The VS Code extension wires this to the editor's "Format Document" command.

Other editors

Any editor that speaks LSP can spawn craftgo-lsp. There is no first-party plugin for Neovim, Helix, Zed, or others today. If you set one up:

• The binary lives at $(which craftgo-lsp) after go install
• It speaks plain LSP over stdin/stdout
• File extension is .craftgo, scope is source.craftgo

Without the VS Code extension you will not have syntax highlighting; the language server still provides completion, hover, and diagnostics. Contributions for other editor integrations are welcome.

Troubleshooting

Completion stopped working

Reinstall and restart:

go install github.com/craftgodotdev/craftgo/cmd/craftgo-lsp@latest
# in VS Code: Cmd+Shift+P -> craftgo: Restart Language Server

Cross-file references show as unresolved

The LSP looks for sibling .craftgo files in the same folder. If your enum lives in enums.craftgo and your type uses it from types.craftgo, both files must sit in the same design/<package>/ subfolder.

Errors on a syntactically valid file

The LSP and the craftgo CLI use the same semantic analyzer. Run craftgo lint <design-dir> to reproduce. If the message is unclear, file a bug.