Helix LSP

Helix can start the Bifrost language server, bifrost-lsp, through its built-in language-server configuration. No Bifrost-specific Helix plugin is needed.

bifrost-lsp is not released yet

Bifrost built after release 0.12.0 does not serve LSP: bifrost --lsp exits with an error. The language server is now the separate bifrost-lsp program, and bifrost-lsp has no release yet. The configuration below is ready for its first release. See LSP Server for the status and for what to use until then.

Put this in ~/.config/helix/languages.toml, start Helix from the workspace root, and open a supported source file:

[language-server.bifrost]
command = "bifrost-lsp"
args = ["--root", "."]

[[language]]
name = "c"
language-servers = ["bifrost"]

[[language]]
name = "cpp"
language-servers = ["bifrost"]

[[language]]
name = "c-sharp"
language-servers = ["bifrost"]

[[language]]
name = "go"
language-servers = ["bifrost"]

[[language]]
name = "java"
language-servers = ["bifrost"]

[[language]]
name = "javascript"
language-servers = ["bifrost"]

[[language]]
name = "jsx"
language-servers = ["bifrost"]

[[language]]
name = "typescript"
language-servers = ["bifrost"]

[[language]]
name = "tsx"
language-servers = ["bifrost"]

[[language]]
name = "php"
language-servers = ["bifrost"]

[[language]]
name = "python"
language-servers = ["bifrost"]

[[language]]
name = "ruby"
language-servers = ["bifrost"]

[[language]]
name = "rust"
language-servers = ["bifrost"]

[[language]]
name = "scala"
language-servers = ["bifrost"]

[[language]]
name = "kotlin"
language-servers = ["bifrost"]

This assumes bifrost-lsp is on PATH. If it is not, set command to the absolute path of the binary.

Bifrost handles only the languages that list bifrost in language-servers. Remove the entries for languages you do not want it to handle.

Workspace Roots

--root is the fallback workspace root. Helix sends the current working directory as rootPath, so args = ["--root", "."] works when you start Helix from the repository root:

cd /path/to/project
hx src/main/java/example/App.java

If you start Helix outside the project, pass an absolute root instead:

[language-server.bifrost]
command = "bifrost-lsp"
args = ["--root", "/path/to/project"]

Helix supports multiple language servers per language. If you want Bifrost to coexist with a language-specific server, include both names in that language’s list:

[[language]]
name = "java"
language-servers = ["bifrost", "jdtls"]

Running multiple servers can be useful when another server provides formatting or diagnostics, but it can also produce duplicate or competing navigation results. Keep the language-servers list to Bifrost alone if you want Bifrost to be the only server Helix uses for that language.

Confirm Bifrost Is Running

Check that Helix can find the configured Bifrost server:

hx --health java

The language server section should list bifrost with a check mark and the command path Helix will run.

To capture startup and request logs, launch Helix with an explicit log file:

hx -vvv --log /tmp/helix-bifrost.log src/main/java/example/App.java

Open a supported file and use Helix’s normal LSP navigation commands, such as gd for go to definition or gr for references. The log should show initialize, textDocument/definition, or textDocument/references messages for bifrost.

For request timing from the server, set the two variables that the VS Code extension passes to bifrost-lsp. BIFROST_LSP_DEBUG = "1" logs every request and notification. BIFROST_LSP_SLOW_MS logs requests that take at least that many milliseconds; 0 logs all of them. The bifrost CLI does not read these variables. See LSP Server.

[language-server.bifrost]
command = "bifrost-lsp"
args = ["--root", "."]
environment = { BIFROST_LSP_DEBUG = "1", BIFROST_LSP_SLOW_MS = "0" }